National Library of Energy BETA

Sample records for ruthenium dimer catalysis

  1. Surface Catalysis of Water Oxidation by the Blue Ruthenium Dimer

    SciTech Connect (OSTI)

    Jurss, Jonah W.; Concepcion, Javier C.; Norris, Michael R.; Templeton, Joseph L.; Meyer, Thomas J.

    2010-04-08

    Single-electron activation of multielectron catalysis has been shown to be viable in catalytic water oxidation with stepwise proton-coupled electron transfer, leading to high-energy catalytic precursors. For the blue dimer, cis,cis-[(bpy)2(H2O)RuIIIORuIII(H2O)(bpy)2]4+, the first well-defined molecular catalyst for water oxidation, stepwise 4e-/4H+ oxidation occurs to give the reactive precursor [(O)RuVORuV(O)]4+. This key intermediate is kinetically inaccessible at an unmodified metal oxide surface, where the only available redox pathway is electron transfer. We report here a remarkable surface activation of indium-tin oxide (In2O3:Sn) electrodes toward catalytic water oxidation by the blue dimer at electrodes derivatized by surface phosphonate binding of [Ru(4,4'-((HO)2P(O)CH2)2bpy)2(bpy)]2+. Surface binding dramatically improves the rate of surface oxidation of the blue dimer and induces water oxidation catalysis.

  2. Structure and Electronic Configurations of the Intermediates of Water Oxidation in Blue Ruthenium Dimer Catalysis

    SciTech Connect (OSTI)

    Moonshiram, Dooshaye; Jurss, Jonah W.; Concepcion, Javier J.; Zakharova, Taisiya; Alperovich, Igor; Meyer, Thomas J.; Pushkar, Yulia

    2013-04-08

    Catalytic O{sub 2} evolution with cis,cis-[(bpy){sub 2}(H{sub 2}O)Ru{sup III}ORu{sup III}(OH{sub 2})(bpy){sub 2}]{sup 4+} (bpy is 2,2-bipyridine), the so-called blue dimer, the first designed water oxidation catalyst, was monitored by UV-vis, EPR, and X-ray absorption spectroscopy (XAS) with ms time resolution. Two processes were identified, one of which occurs on a time scale of 100 ms to a few seconds and results in oxidation of the catalyst with the formation of an intermediate, here termed [3,4]'. A slower process occurring on the time scale of minutes results in the decay of this intermediate and O{sub 2} evolution. Spectroscopic data suggest that within the fast process there is a short-lived transient intermediate, which is a precursor of [3,4]'. When excess oxidant was used, a highly oxidized form of the blue dimer [4,5] was spectroscopically resolved within the time frame of the fast process. Its structure and electronic state were confirmed by EPR and XAS. As reported earlier, the [3,4]' intermediate likely results from reaction of [4,5] with water. While it is generated under strongly oxidizing conditions, it does not display oxidation of the Ru centers past [3,4] according to EPR and XAS. EXAFS analysis demonstrates a considerably modified ligand environment in [3,4]'. Raman measurements confirmed the presence of the O-O fragment by detecting a new vibration band in [3,4]' that undergoes a 46 cm{sup -1} shift to lower energy upon {sup 16}O/{sup 18}O exchange. Under the conditions of the experiment at pH 1, the [3,4]' intermediate is the catalytic steady state form of the blue dimer catalyst, suggesting that its oxidation is the rate-limiting step.

  3. Sensitivity of the Properties of Ruthenium Blue Dimer to Method, Basis Set, and Continuum Model

    SciTech Connect (OSTI)

    Ozkanlar, Abdullah; Clark, Aurora E.

    2012-05-23

    The ruthenium blue dimer [(bpy)2RuIIIOH2]2O4+ is best known as the first well-defined molecular catalyst for water oxidation. It has been subject to numerous computational studies primarily employing density functional theory. However, those studies have been limited in the functionals, basis sets, and continuum models employed. The controversy in the calculated electronic structure and the reaction energetics of this catalyst highlights the necessity of benchmark calculations that explore the role of density functionals, basis sets, and continuum models upon the essential features of blue-dimer reactivity. In this paper, we report Kohn-Sham complete basis set (KS-CBS) limit extrapolations of the electronic structure of blue dimer using GGA (BPW91 and BP86), hybrid-GGA (B3LYP), and meta-GGA (M06-L) density functionals. The dependence of solvation free energy corrections on the different cavity types (UFF, UA0, UAHF, UAKS, Bondi, and Pauling) within polarizable and conductor-like polarizable continuum model has also been investigated. The most common basis sets of double-zeta quality are shown to yield results close to the KS-CBS limit; however, large variations are observed in the reaction energetics as a function of density functional and continuum cavity model employed.

  4. Deprotonated Water Dimers: The Building Blocks of Segmented Water Chains on Rutile RuO2(110)

    SciTech Connect (OSTI)

    Mu, Rentao; Cantu Cantu, David; Glezakou, Vassiliki Alexandra; Lyubinetsky, Igor; Rousseau, Roger J.; Dohnalek, Zdenek

    2015-10-15

    Despite the importance of RuO2 in photocatalytic water splitting and catalysis in general, the interactions of water with even its most stable (110) surface are not well-understood. In this study we employ a combination of high-resolution scanning tunneling microscopy imaging with density functional theory based ab initio molecular dynamics, and we follow the formation and binding of linear water clusters on coordinatively unsaturated ruthenium rows. We find that clusters of all sizes (dimers, trimers, tetramers, extended chains) are stabilized by donating one proton per every two water molecules to the surface bridge bonded oxygen sites, in contrast with water monomers that do not show a significant propensity for dissociation. The clusters with odd number of water molecules are less stable than the clusters with even number, and are generally not observed under thermal equilibrium. For all clusters with even numbers, the dissociated dimers represent the fundamental building blocks with strong intra-dimer hydrogen bonds and only very weak inter-dimer interactions resulting in segmented water chains.

  5. Catalysis Workshop

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Opportunities in Catalysis Research Using Synchrotron Radiation Stanford Synchrotron Radiation Laboratory October 8-9, 2002 Organizer: Anders Nilsson Chemical catalysis is one of the research areas of enormous importance for the industrial society. There are important challenges to be met in the near future where development of new processes and catalysts are a necessity. We need to find a way to make methanol from methane, split water into hydrogen using sunlight, find replacement of platinum

  6. Dendrimer-Encapsulated Ruthenium Nanoparticles as Catalysts for Lithium-O2 Batteries

    SciTech Connect (OSTI)

    Bhattacharya, Priyanka; Nasybulin, Eduard N.; Engelhard, Mark H.; Kovarik, Libor; Bowden, Mark E.; Li, Shari; Gaspar, Daniel J.; Xu, Wu; Zhang, Jiguang

    2014-12-01

    Dendrimer-encapsulated ruthenium nanoparticles (DEN-Ru) have been used as catalysts in lithium-O2 batteries for the first time. Results obtained from UV-vis spectroscopy, electron microscopy and X-ray photoelectron spectroscopy show that the nanoparticles synthesized by the dendrimer template method are ruthenium oxide instead of metallic ruthenium reported earlier by other groups. The DEN-Ru significantly improve the cycling stability of lithium (Li)-O2 batteries with carbon black electrodes and decrease the charging potential even at low catalyst loading. The monodispersity, porosity and large number of surface functionalities of the dendrimer template prevent the aggregation of the ruthenium nanoparticles making their entire surface area available for catalysis. The potential of using DEN-Ru as stand-alone cathode materials for Li-O2 batteries is also explored.

  7. RUTHENIUM DECONTAMINATION METHOD

    DOE Patents [OSTI]

    Gresky, A.T.

    1960-07-19

    A liquid-liquid extraction method of separating uranium from fission products is given. A small amount of a low molecular weight ketone is added to an acidic aqueous solution containing neutron-irradiated uranium and its associated fission products. The resulting solution is digested and then contacted with an organic liquid that extracts uranium values. The purpose of the step of digesting the aqueous solution in the presence of the ketone is to suppress the extractability of ruthenium.

  8. Structure of a Loose Dimer: an Intermediate in Nitric Oxide Synthase Assembly

    SciTech Connect (OSTI)

    Pant,K.; Crane, B.

    2005-01-01

    Cooperativity among ligand binding, subunit association, and protein folding has implications for enzyme regulation as well as protein aggregation events associated with disease. The binding of substrate l-arginine or cofactor tetrahydrobiopterin converts nitric oxide synthases (NOSs) from a 'loose dimer', with an exposed active center and higher sensitivity to proteolysis, to a 'tight dimer' competent for catalysis. The crystallographic structure of the Bacillus subtilis NOS loose dimer shows an altered association state with severely destabilized subdomains. Ligand binding or heme reduction converts loose dimers to tight dimers in solution and crystals. Mutations at key positions in the dimer interface that distinguish prokaryotic from eukaryotic NOSs affect the propensity to form loose dimers. The loose dimer structure indicates that non-native interactions can mediate subunit association in NOS.

  9. SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS

    DOE Patents [OSTI]

    Callis, C.F.; Moore, R.L.

    1959-09-01

    >The separation of ruthenium from aqueous solutions containing uranium plutonium, ruthenium, and fission products is described. The separation is accomplished by providing a nitric acid solution of plutonium, uranium, ruthenium, and fission products, oxidizing plutonium to the hexavalent state with sodium dichromate, contacting the solution with a water-immiscible organic solvent, such as hexone, to extract plutonyl, uranyl, ruthenium, and fission products, reducing with sodium ferrite the plutonyl in the solvent phase to trivalent plutonium, reextracting from the solvent phase the trivalent plutonium, ruthenium, and some fission products with an aqueous solution containing a salting out agent, introducing ozone into the aqueous acid solution to oxidize plutonium to the hexavalent state and ruthenium to ruthenium tetraoxide, and volatizing off the ruthenium tetraoxide.

  10. Moderated ruthenium fischer-tropsch synthesis catalyst

    DOE Patents [OSTI]

    Abrevaya, Hayim (Wilmette, IL)

    1991-01-01

    The subject Fischer-Tropsch catalyst comprises moderated ruthenium on an inorganic oxide support. The preferred moderator is silicon. Preferably the moderator is effectively positioned in relationship to ruthenium particles through simultaneous placement on the support using reverse micelle impregnation.

  11. 2012 Catalysis Lectures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Catalysis Lectures May 21-24 2012 Bert Weckhuysen Bert Weckhuysen, who holds the chair of Inorganic Chemistry and Catalysis at Utrecht University, will give a series of catalysis lectures during his sabbatical period at Stanford University and SLAC. (1) "Characterization of Heterogeneous Catalysts: Possibilities and Limitations of In-situ Spectroscopy" (Part I) Monday, May 21, 2012, 4.30-6 p.m. Location: SLAC Redwood Conference Room C&D (2) "Characterization of Heterogeneous

  12. SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS

    DOE Patents [OSTI]

    Beederman, M.; Vogler, S.; Hyman, H.H.

    1959-07-14

    The separation of rathenium from a rathenium containing aqueous solution is described. The separation is accomplished by adding sodium nitrite, silver nitrate and ozone to the ruthenium containing aqueous solution to form ruthenium tetroxide and ihen volatilizing off the ruthenium tetroxide.

  13. Selective deposition of nanostructured ruthenium oxide using...

    Office of Scientific and Technical Information (OSTI)

    Title: Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for micro-supercapacitors in solid Nafion electrolyte Authors: Gnerlich, Markus ; Ben-Yoav, ...

  14. Photochemical dimerization of organic compounds

    DOE Patents [OSTI]

    Crabtree, Robert H.; Brown, Stephen H.; Muedas, Cesar A.; Ferguson, Richard R.

    1992-01-01

    At least one of selectivity and reaction rate of photosensitized vapor phase dimerizations, including dehydrodimerizations, hydrodimerizations and cross-dimerizations of saturated and unsaturated organic compounds is improved by conducting the dimerization in the presence of hydrogen or nitrous oxide.

  15. Zeolite catalysis: technology

    SciTech Connect (OSTI)

    Heinemann, H.

    1980-07-01

    Zeolites have been used as catalysts in industry since the early nineteen sixties. The great majority of commercial applications employ one of three zeolite types: zeolite Y; Mordenite; ZSM-5. By far the largest use of zeolites is in catalytic cracking, and to a lesser extent in hydrocracking. This paper reviews the rapid development of zeolite catalysis and its application in industries such as: the production of gasoline by catalytic cracking of petroleum; isomerization of C/sub 5/ and C/sub 6/ paraffin hydrocarbons; alkylation of aromatics with olefins; xylene isomerization; and conversion of methanol to gasoline.

  16. Electron Microscopy Catalysis Projects: Success Stories from...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Electron Microscopy Catalysis Projects: Success Stories from the High Temperature Materials Laboratory (HTML) User Program Electron Microscopy Catalysis Projects: Success Stories ...

  17. Catalysis and Synthesis | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Catalysis and Synthesis Catalysis and Synthesis Many different types of chemical reactions depend on catalysts in order to work, and the hunt for better catalysts has deep...

  18. Catalysis Capabilities | Argonne National Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Catalysis Research Areas Facilities and Equipment Intellectual Property Publications Staff Partnerships Licensing Sponsored Research Technical Services Technologist in Residence News Press Releases Feature Stories In the News Photos Videos Ombudsman Ombudsman Argonne National Laboratory Technology Development and Commercialization About Technologies Available for Licensing Capabilities Partnerships News Capabilities Catalysis Research Areas Facilities and Equipment Intellectual Property

  19. Platinum-ruthenium-palladium fuel cell electrocatalyst

    DOE Patents [OSTI]

    Gorer, Alexander

    2006-02-07

    A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum at a concentration that is between about 20 and about 60 atomic percent, ruthenium at a concentration that is between about 20 and about 60 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having an atomic ratio of platinum to ruthenium that is between about 0.7 and about 1.2. Alternatively, the catalyst may contain platinum at a concentration that is between about 25 and about 50 atomic percent, ruthenium at a concentration that is between about 25 and about 55 atomic percent, palladium at a concentration that is between about 5 and about 45 atomic percent, and having a difference between the concentrations of ruthenium and platinum that is no greater than about 20 atomic percent.

  20. Platinum-ruthenium-nickel fuel cell electrocatalyst

    DOE Patents [OSTI]

    Gorer, Alexander

    2005-07-26

    A catalyst suitable for use in a fuel cell, especially as an anode catalyst, that contains platinum, ruthenium, and nickel, wherein the nickel is at a concentration that is less than about 10 atomic percent.

  1. 2013 DOE Catalysis Working Group Meeting Agenda | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    DOE Catalysis Working Group Meeting Agenda 2013 DOE Catalysis Working Group Meeting Agenda Agenda for the 2013 DOE Catalysis Working Group Meeting on May 15, 2013. PDF icon...

  2. Enhanced Micellar Catalysis LDRD.

    SciTech Connect (OSTI)

    Betty, Rita G.; Tucker, Mark David; Taggart, Gretchen; Kinnan, Mark K.; Glen, Crystal Chanea; Rivera, Danielle; Sanchez, Andres; Alam, Todd Michael

    2012-12-01

    The primary goals of the Enhanced Micellar Catalysis project were to gain an understanding of the micellar environment of DF-200, or similar liquid CBW surfactant-based decontaminants, as well as characterize the aerosolized DF-200 droplet distribution and droplet chemistry under baseline ITW rotary atomization conditions. Micellar characterization of limited surfactant solutions was performed externally through the collection and measurement of Small Angle X-Ray Scattering (SAXS) images and Cryo-Transmission Electron Microscopy (cryo-TEM) images. Micellar characterization was performed externally at the University of Minnesota's Characterization Facility Center, and at the Argonne National Laboratory Advanced Photon Source facility. A micellar diffusion study was conducted internally at Sandia to measure diffusion constants of surfactants over a concentration range, to estimate the effective micelle diameter, to determine the impact of individual components to the micellar environment in solution, and the impact of combined components to surfactant phase behavior. Aerosolized DF-200 sprays were characterized for particle size and distribution and limited chemical composition. Evaporation rates of aerosolized DF-200 sprays were estimated under a set of baseline ITW nozzle test system parameters.

  3. Biomimetic Chalcogels for Solar Fuel Catalysis | ANSER Center...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Biomimetic Chalcogels for Solar Fuel Catalysis Home > Research > ANSER Research Highlights > Biomimetic Chalcogels for Solar Fuel Catalysis...

  4. Integrated Mesoscale Architectures for Sustainable Catalysis...

    Office of Science (SC) Website

    Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC) Energy Frontier ... science, molecular dynamics (MD), density functional theory (DFT), quantum ...

  5. Catalysis Working Group Meeting: June 2015

    Broader source: Energy.gov [DOE]

    Agenda and presentations from the Catalysis Working Group meeting held on June 8, 2015, in Arlington, Virginia.

  6. Thermoelectric Properties of Rare-Earth-Ruthenium-Germanium Compounds...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cobalt substitution for ruthenium enhances the semiconductor character but does not improve the thermoelectric properties. URL: Link to article - Journal of Applied Physics...

  7. Reaction Selectivity in Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Somorjai, Gabor A.; Kliewer, Christopher J.

    2009-02-02

    The understanding of selectivity in heterogeneous catalysis is of paramount importance to our society today. In this review we outline the current state of the art in research on selectivity in heterogeneous catalysis. Current in-situ surface science techniques have revealed several important features of catalytic selectivity. Sum frequency generation vibrational spectroscopy has shown us the importance of understanding the reaction intermediates and mechanism of a heterogeneous reaction, and can readily yield information as to the effect of temperature, pressure, catalyst geometry, surface promoters, and catalyst composition on the reaction mechanism. DFT calculations are quickly approaching the ability to assist in the interpretation of observed surface spectra, thereby making surface spectroscopy an even more powerful tool. HP-STM has revealed three vitally important parameters in heterogeneous selectivity: adsorbate mobility, catalyst mobility, and selective site-blocking. The development of size controlled nanoparticles from 0.8 to 10 nm, of controlled shape, and of controlled bimetallic composition has revealed several important variables for catalytic selectivity. Lastly, DFT calculations may be paving the way to guiding the composition choice for multi-metallic heterogeneous catalysis for the intelligent design of catalysts incorporating the many factors of selectivity we have learned.

  8. Workshop: Synchrotron Applications in Chemical Catalysis | Stanford...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Applications in Chemical Catalysis Tuesday, October 25, 2011 - 8:00am 2011 SSRLLCLS Annual Users Conference This workshop, part of the 2011 SSRLLCLS Annual Users...

  9. Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make Fuels and Chemicals BETO works with the emerging U.S. bioindustry to sustainably convert non-food ...

  10. Basic Research Needs: Catalysis for Energy

    SciTech Connect (OSTI)

    Bell, Alexis T.; Gates, Bruce C.; Ray, Douglas; Thompson, Michael R.

    2008-03-11

    The report presents results of a workshop held August 6-8, 2007, by DOE SC Basic Energy Sciences to determine the basic research needs for catalysis research.

  11. Fischer-Tropsch synthesis process employing a moderated ruthenium catalyst

    DOE Patents [OSTI]

    Abrevaya, Hayim (Wilmette, IL)

    1990-01-01

    A Fischer-Tropsch type process produces hydrocarbons from carbon monoxide and hydrogen using a novel catalyst comprising moderated ruthenium on an inorganic oxide support. The preferred moderator is silicon. Preferably the moderator is effectively positioned in relationship to ruthenium particles through simultaneous placement on the support using reverse micelle impregnation.

  12. Fischer-Tropsch synthesis process employing a moderated ruthenium catalyst

    DOE Patents [OSTI]

    Abrevaya, H.

    1990-07-31

    A Fischer-Tropsch type process produces hydrocarbons from carbon monoxide and hydrogen using a novel catalyst comprising moderated ruthenium on an inorganic oxide support. The preferred moderator is silicon. Preferably the moderator is effectively positioned in relationship to ruthenium particles through simultaneous placement on the support using reverse micelle impregnation. 1 fig.

  13. The energy landscape of ;#8203;adenylate kinase during catalysis...

    Office of Scientific and Technical Information (OSTI)

    The energy landscape of ;8203;adenylate kinase during catalysis Citation Details In-Document Search Title: The energy landscape of ;8203;adenylate kinase during catalysis ...

  14. Materials Design and Discovery: Catalysis and Energy Storage...

    Office of Scientific and Technical Information (OSTI)

    Materials Design and Discovery: Catalysis and Energy Storage (Mira Early Science Program ... Citation Details In-Document Search Title: Materials Design and Discovery: Catalysis and ...

  15. Pre-Competitive Catalysis Research: Fundamental Sulfation/Desulfation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Pre-Competitive Catalysis Research: Fundamental SulfationDesulfation Studies of Lean NOx Traps Pre-Competitive Catalysis Research: Fundamental SulfationDesulfation Studies of...

  16. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO Oxidation Catalysis in Support ...

  17. Biomimetic Chalcogels for Solar Fuel Catalysis | ANSER Center |

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Argonne-Northwestern National Laboratory Biomimetic Chalcogels for Solar Fuel Catalysis Home > Research > ANSER Research Highlights > Biomimetic Chalcogels for Solar Fuel Catalysis

  18. Transmural Catalysis - High Efficiency Catalyst Systems for NOx...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Presentation ...

  19. DOE Laboratory Catalysis Research Symposium - Abstracts

    SciTech Connect (OSTI)

    Dunham, T.

    1999-02-01

    The conference consisted of two sessions with the following subtopics: (1) Heterogeneous Session: Novel Catalytic Materials; Photocatalysis; Novel Processing Conditions; Metals and Sulfides; Nuclear Magnetic Resonance; Metal Oxides and Partial Oxidation; Electrocatalysis; and Automotive Catalysis. (2) Homogeneous Catalysis: H-Transfer and Alkane Functionalization; Biocatalysis; Oxidation and Photocatalysis; and Novel Medical, Methods, and Catalyzed Reactions.

  20. Ruthenium / aerogel nanocomposits via Atomic Layer Deposition

    SciTech Connect (OSTI)

    Biener, J; Baumann, T F; Wang, Y; Nelson, E J; Kucheyev, S O; Hamza, A V; Kemell, M; Ritala, M; Leskela, M

    2006-08-28

    We present a general approach to prepare metal/aerogel nanocomposites via template directed atomic layer deposition (ALD). In particular, we used a Ru ALD process consisting of alternating exposures to bis(cyclopentadienyl)ruthenium (RuCp{sub 2}) and air at 350 C to deposit metallic Ru nanoparticles on the internal surfaces of carbon and silica aerogels. The process does not affect the morphology of the aerogel template and offers excellent control over metal loading by simply adjusting the number of ALD cycles. We also discuss the limitations of our ALD approach, and suggest ways to overcome these.

  1. "Nanocrystal bilayer for tandem catalysis"

    SciTech Connect (OSTI)

    Yamada, Yusuke; Tsung, Chia Kuang; Huang, Wenyu; Huo, Ziyang; E.Habas, Susan E; Soejima, Tetsuro; Aliaga, Cesar E; Samorjai, Gabor A; Yang, Peidong

    2011-01-24

    Supported catalysts are widely used in industry and can be optimized by tuning the composition and interface of the metal nanoparticles and oxide supports. Rational design of metal-metal oxide interfaces in nanostructured catalysts is critical to achieve better reaction activities and selectivities. We introduce here a new class of nanocrystal tandem catalysts that have multiple metal-metal oxide interfaces for the catalysis of sequential reactions. We utilized a nanocrystal bilayer structure formed by assembling platinum and cerium oxide nanocube monolayers of less than 10 nm on a silica substrate. The two distinct metal-metal oxide interfaces, CeO2-Pt and Pt-SiO2, can be used to catalyse two distinct sequential reactions. The CeO2-Pt interface catalysed methanol decomposition to produce CO and H2, which were subsequently used for ethylene hydroformylation catalysed by the nearby Pt-SiO2 interface. Consequently, propanal was produced selectively from methanol and ethylene on the nanocrystal bilayer tandem catalyst. This new concept of nanocrystal tandem catalysis represents a powerful approach towards designing high-performance, multifunctional nanostructured catalysts

  2. PROCESS FOR DECONTAMINATING THORIUM AND URANIUM WITH RESPECT TO RUTHENIUM

    DOE Patents [OSTI]

    Meservey, A.A.; Rainey, R.H.

    1959-10-20

    The control of ruthenium extraction in solvent-extraction processing of neutron-irradiated thorium is presented. Ruthenium is rendered organic-insoluble by the provision of sulfite or bisulfite ions in the aqueous feed solution. As a result the ruthenium remains in the aqueous phase along with other fission product and protactinium values, thorium and uranium values being extracted into the organic phase. This process is particularly applicable to the use of a nitrate-ion-deficient aqueous feed solution and to the use of tributyl phosphate as the organic extractant.

  3. Nanocrystal assembly for tandem catalysis

    DOE Patents [OSTI]

    Yang, Peidong; Somorjai, Gabor; Yamada, Yusuke; Tsung, Chia-Kuang; Huang, Wenyu

    2014-10-14

    The present invention provides a nanocrystal tandem catalyst comprising at least two metal-metal oxide interfaces for the catalysis of sequential reactions. One embodiment utilizes a nanocrystal bilayer structure formed by assembling sub-10 nm platinum and cerium oxide nanocube monolayers on a silica substrate. The two distinct metal-metal oxide interfaces, CeO.sub.2--Pt and Pt--SiO.sub.2, can be used to catalyze two distinct sequential reactions. The CeO.sub.2--Pt interface catalyzed methanol decomposition to produce CO and H.sub.2, which were then subsequently used for ethylene hydroformylation catalyzed by the nearby Pt--SiO.sub.2 interface. Consequently, propanal was selectively produced on this nanocrystal bilayer tandem catalyst.

  4. Nickel/ruthenium catalyst and method for aqueous phase reactions

    DOE Patents [OSTI]

    Elliott, Douglas C.; Sealock, John L.

    1998-01-01

    A method of hydrogenation using a catalyst in the form of a plurality of porous particles wherein each particle is a support having nickel metal catalytic phase or reduced nickel deposited thereon in a first dispersed phase and an additional ruthenium metal deposited onto the support in a second dispersed phase. The additional ruthenium metal is effective in retarding or reducing agglomeration or sintering of the nickel metal catalytic phase thereby increasing the life time of the catalyst during hydrogenation reactions.

  5. Catalysis Working Group Meeting: June 2014

    Broader source: Energy.gov [DOE]

    Agenda and presentations from the Catalysis Working Group held on June 16, 2014, in Washington, D.C., in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting.

  6. Catalysis Working Group Meeting: May 2013

    Broader source: Energy.gov [DOE]

    Information from the Catalysis Working Group meeting held on May 15, 2013, in Arlington, Virginia, in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting.

  7. Workshop: Synchrotron Applications in Chemical Catalysis | Stanford

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Synchrotron Radiation Lightsource Synchrotron Applications in Chemical Catalysis Tuesday, October 25, 2011 - 8:00am 2011 SSRL/LCLS Annual Users Conference This workshop, part of the 2011 SSRL/LCLS Annual Users Conference, will focus on understanding processes in homogeneous (both biological and small molecule) and heterogeneous catalysis, using synchrotron-based methods. The workshop will cover more traditional applications (using XANES and EXAFS), as well as applications of XES, RIXS and

  8. Fiber optic D dimer biosensor

    DOE Patents [OSTI]

    Glass, R.S.; Grant, S.A.

    1999-08-17

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy. 4 figs.

  9. Fiber optic D dimer biosensor

    DOE Patents [OSTI]

    Glass, Robert S.; Grant, Sheila A.

    1999-01-01

    A fiber optic sensor for D dimer (a fibrinolytic product) can be used in vivo (e.g., in catheter-based procedures) for the diagnosis and treatment of stroke-related conditions in humans. Stroke is the third leading cause of death in the United States. It has been estimated that strokes and stroke-related disorders cost Americans between $15-30 billion annually. Relatively recently, new medical procedures have been developed for the treatment of stroke. These endovascular procedures rely upon the use of microcatheters. These procedures could be facilitated with this sensor for D dimer integrated with a microcatheter for the diagnosis of clot type, and as an indicator of the effectiveness, or end-point of thrombolytic therapy.

  10. Advanced Resources for Catalysis Science; Recommendations for a National Catalysis Research Institute

    SciTech Connect (OSTI)

    Peden, Charles HF.; Ray, Douglas

    2005-10-05

    Catalysis is one of the most valuable contributors to our economy and historically an area where the United States has enjoyed, but is now losing, international leadership. While other countries are stepping up their work in this area, support for advanced catalysis research and development in the U.S. has diminished. Yet, more than ever, innovative and improved catalyst technologies are imperative for new energy production processes to ease our dependence on imported resources, for new energy-efficient and environmentally benign chemical production processes, and for new emission reduction technologies to minimize the environmental impact of an active and growing economy. Addressing growing concerns about the future direction of U.S. catalysis science, experts from the catalysis community met at a workshop to determine and recommend advanced resources needed to address the grand challenges for catalysis research and development. The workshop's primary conclusion: To recapture our position as the leader in catalysis innovation and practice, and promote crucial breakthroughs, the U.S. must establish one or more well-funded and well-equipped National Catalysis Research Institutes competitively selected, centered in the national laboratories and, by charter, networked to other national laboratories, universities, and industry. The Institute(s) will be the center of a national collaboratory that gives catalysis researchers access to the most advanced techniques available in the scientific enterprise. The importance of catalysis to our energy, economic, and environmental security cannot be overemphasized. Catalysis is a vital part of our core industrial infrastructure, as it is integral to chemical processing and petroleum refining, and is critical to proposed advances needed to secure a sustainable energy future. Advances in catalysis could reduce our need for foreign oil by making better use of domestic carbon resources, for example, allowing cost-effective and zero emission conversion of coal into transportation fuels. No matter what energy sources are being considered (oil, natural gas, coal, biomass, solar, or nuclear based), a clean, sustainable energy future will involve catalysis to improve energy efficiency and storage and use options, and to mitigate environmental impacts. Recent revolutionary advances in nanotechnology and high-performance computing are enabling the breakthroughs in catalysis science and technology essential for a secure energy future. Thus, the time is right for substantially increased investments in catalysis science and technology.

  11. Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsourc...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Shining Light on Catalysis Tuesday, July 19, 2011 - 4:38pm SSRL Conference Room 137-322 Jeroen A. van Bokhoven, Professor for Heterogeneous Catalysis Institute for Chemical and...

  12. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis ALS X-Rays Shine a New Light on Catalysis Print Thursday, 21 May 2015 11:16 Electrocatalysts are responsible for expediting reactions in...

  13. Catalysis Science | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Catalysis Science Chemical Sciences, Geosciences, & Biosciences (CSGB) Division CSGB Home ... principles enabling rational catalyst design and chemical transformation control. ...

  14. Opportunities in Catalysis Research Using Synchrotron Radiation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    in Catalysis Research Using Synchrotron Radiation Tuesday 10/8/02 Chair: Lars Pettersson 1:30-1:40 Anders Nilsson Welcome 1:40-2:30 Gabor Somorjai University of California, Berkeley and LBLN Need for New Directions of Research at the Frontiers of Catalysis Science 2:30-3:00 Geoff Thornton University of Manchester Influence of defects on the reactivity of ZnO 3:00-3:30 Anders Nilsson Stanford Synchrotron Radiation Laboratory Soft X-ray Spectroscopy of Surfaces and Reactions 3:30-3:45 Break Chair:

  15. Catalytic Water Oxidation by Single-Site Ruthenium Catalysts

    SciTech Connect (OSTI)

    Concepcion, Javier C.; Jurss, Jonah W.; Norris, Michael R.; Chen, Zuofeng; Templeton, Joseph L.; Meyer, Thomas J.

    2010-01-08

    A series of monomeric ruthenium polypyridyl complexes have been synthesized and characterized, and their performance as water oxidation catalysts has been evaluated. The diversity of ligand environments and how they influence rates and reaction thermodynamics create a platform for catalyst design with controllable reactivity based on ligand variations.

  16. PRECIPITATION OF ZIRCONIUM, NIOBIUM, AND RUTHENIUM FROM AQUEOUS SOLUTIONS

    DOE Patents [OSTI]

    Wilson, A.S.

    1958-08-12

    An improvement on the"head end process" for decontaminating dissolver solutions of their Zr, Ni. and Ru values. The process consists in adding a water soluble symmetrical dialkyl ketone. e.g. acetone, before the formation of the manganese dioxide precipitate. The effect is that upon digestion, the ruthenium oxide does not volatilize, but is carried on the manganese dioxide precipitate.

  17. Electronic transitions of palladium dimer

    SciTech Connect (OSTI)

    Qian, Yue; Ng, Y. W.; Chen, Zhihua; Cheung, A. S.-C., E-mail: hrsccsc@hku.hk [Department of Chemistry, The University of Hong Kong, Pokfulam Road (Hong Kong)

    2013-11-21

    The laser induced fluorescence spectrum of palladium dimer (Pd{sub 2}) in the visible region between 480 and 700 nm has been observed and analyzed. The gas-phase Pd{sub 2} molecule was produced by laser ablation of palladium metal rod. Eleven vibrational bands were observed and assigned to the [17.1] {sup 3}II{sub g} - X{sup 3}?{sub u}{sup +} transition system. The bond length (r{sub o}) and vibrational frequency (?G{sub 1/2}) of the ground X{sup 3}?{sub u}{sup +} state were determined to be 2.47(4) and 211.4(5) cm{sup ?1}, respectively. A molecular orbital energy level diagram was used to understand the observed ground and excited electronic states. This is the first gas-phase experimental investigation of the electronic transitions of Pd{sub 2}.

  18. IRAK4 Dimerization and Trans-Autophosphorylation Are Induced...

    Office of Scientific and Technical Information (OSTI)

    IRAK4 Dimerization and Trans-Autophosphorylation Are Induced by Myddosome Assembly Citation Details In-Document Search Title: IRAK4 Dimerization and Trans-Autophosphorylation Are ...

  19. Heterogeneous Catalysis for Thermochemical Conversion | Bioenergy | NREL

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Heterogeneous Catalysis for Thermochemical Conversion Our mission is to transform thermal biomass deconstruction products (syngas and pyrolysis oil) into the fuels and chemicals that keep society moving forward. Figure includes three panels. The first pane, labeled single-source precursors, depicts a bis(triphenylphosphine)rhodium(I) carbonyl chloride single-source precursor for producing rhodium phosphide nanoparticles, shown by a vertical line labeled PPh3 at the top, Rh in the middle, and

  20. USD Catalysis Group for Alternative Energy

    SciTech Connect (OSTI)

    Hoefelmeyer, James D.; Koodali, Ranjit; Sereda, Grigoriy; Engebretson, Dan; Fong, Hao; Puszynski, Jan; Shende, Rajesh; Ahrenkiel, Phil

    2012-03-13

    The South Dakota Catalysis Group (SDCG) is a collaborative project with mission to develop advanced catalysts for energy conversion with two primary goals: (1) develop photocatalytic systems in which polyfunctionalized TiO2 are the basis for hydrogen/oxygen synthesis from water and sunlight (solar fuels group), (2) develop new materials for hydrogen utilization in fuel cells (fuel cell group). In tandem, these technologies complete a closed chemical cycle with zero emissions.

  1. Nanoscale Advances in Catalysis and Energy Applications

    SciTech Connect (OSTI)

    Li, Yimin; Somorjai, Gabor A.

    2010-05-12

    In this perspective, we present an overview of nanoscience applications in catalysis, energy conversion, and energy conservation technologies. We discuss how novel physical and chemical properties of nanomaterials can be applied and engineered to meet the advanced material requirements in the new generation of chemical and energy conversion devices. We highlight some of the latest advances in these nanotechnologies and provide an outlook at the major challenges for further developments.

  2. Platinum-ruthenium-nickel alloy for use as a fuel cell catalyst

    DOE Patents [OSTI]

    Gorer, Alexander

    2003-01-01

    An improved noble metal alloy composition for a fuel cell catalyst, the alloy containing platinum, ruthenium, and nickel. The alloy shows methanol oxidation activity.

  3. Platinum-ruthenium-nickel alloy for use as a fuel cell catalyst

    DOE Patents [OSTI]

    Gorer, Alexander

    2004-04-20

    An improved noble metal alloy composition for a fuel cell catalyst, the alloy containing platinum, ruthenium, and nickel. The alloy shows methanol oxidation activity.

  4. Neutrons for Catalysis: A Workshop on Neutron Scattering Techniques for Studies in Catalysis

    SciTech Connect (OSTI)

    Overbury, Steven {Steve} H; Coates, Leighton; Herwig, Kenneth W; Kidder, Michelle

    2011-10-01

    This report summarizes the Workshop on Neutron Scattering Techniques for Studies in Catalysis, held at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) on September 16 and 17, 2010. The goal of the Workshop was to bring experts in heterogeneous catalysis and biocatalysis together with neutron scattering experimenters to identify ways to attack new problems, especially Grand Challenge problems in catalysis, using neutron scattering. The Workshop locale was motivated by the neutron capabilities at ORNL, including the High Flux Isotope Reactor (HFIR) and the new and developing instrumentation at the SNS. Approximately 90 researchers met for 1 1/2 days with oral presentations and breakout sessions. Oral presentations were divided into five topical sessions aimed at a discussion of Grand Challenge problems in catalysis, dynamics studies, structure characterization, biocatalysis, and computational methods. Eleven internationally known invited experts spoke in these sessions. The Workshop was intended both to educate catalyst experts about the methods and possibilities of neutron methods and to educate the neutron community about the methods and scientific challenges in catalysis. Above all, it was intended to inspire new research ideas among the attendees. All attendees were asked to participate in one or more of three breakout sessions to share ideas and propose new experiments that could be performed using the ORNL neutron facilities. The Workshop was expected to lead to proposals for beam time at either the HFIR or the SNS; therefore, it was expected that each breakout session would identify a few experiments or proof-of-principle experiments and a leader who would pursue a proposal after the Workshop. Also, a refereed review article will be submitted to a prominent journal to present research and ideas illustrating the benefits and possibilities of neutron methods for catalysis research.

  5. Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Bioproducts | Department of Energy Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts The Bioenergy Technologies Office works with industry to develop pathways that use heat, pressure, and catalysis to convert domestic, non-food biomass into gasoline, jet fuel, and other products. PDF icon thermochemical_four_pager.pdf More Documents & Publications 2013 Peer Review

  6. Catalysis Working Group Meeting: January 2015 | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    January 2015 Catalysis Working Group Meeting: January 2015 The Catalysis Working Group held a meeting on January 21, 2015, in Los Alamos, New Mexico. Meeting Agenda and Presentations PDF icon Catalysis Working Group January 2015 Meeting Agenda PDF icon Electrocatalysts with Ultra-Low PGM Loadings-Vojislav Stamenkovic, Argonne National Laboratory PDF icon Improving Stability and Activity of Pt Monolayer in Non-Pt Core-Shell Electrocatalysts-Radoslav Adzic, Brookhaven National Laboratory PDF icon

  7. Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsource

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Shining Light on Catalysis Tuesday, July 19, 2011 - 4:38pm SSRL Conference Room 137-322 Jeroen A. van Bokhoven, Professor for Heterogeneous Catalysis Institute for Chemical and Bioengineering ETH Zurich Head of Laboratory for Catalysis and Sustainable Chemistry (LSK) Swiss Light Source Paul Scherrer Institute Understanding a functioning catalyst requires understanding at the atomic scales in a time-resolved manner. X-rays can be readily used to accomplish that task, because of the large

  8. Complex of transferrin with ruthenium for medical applications

    DOE Patents [OSTI]

    Richards, Powell; Srivastava, Suresh C.; Meinken, George E.

    1984-05-15

    A novel Ruthenium-transferrin complex, prepared by reacting iron-free human transferrin dissolved in a sodium acetate solution at pH 7 with ruthenium by heating at about 40.degree. C. for about 2 hours, and purifying said complex by means of gel chromotography with pH 7 sodium acetate as eluent. The mono- or di-metal complex produced can be used in nuclear medicine in the diagnosis and/or treatment of tumors and abscesses. Comparative results with Ga-67-citrate, which is the most widely used tumor-localizing agent in nuclear medicine, indicate increased sensitivity of detection and greater tumor uptake with the Ru-transferrin complex.

  9. Complex of transferrin with ruthenium for medical applications

    DOE Patents [OSTI]

    Richards, P.; Srivastava, S.C.; Meinken, G.E.

    1984-05-15

    A novel ruthenium-transferrin complex is disclosed which is prepared by reacting iron-free human transferrin dissolved in a sodium acetate solution at pH 7 with ruthenium by heating at about 40 C for about 2 hours. The complex is purified by means of gel chromotography with pH 7 sodium acetate as eluent. The mono- or di-metal complex produced can be used in nuclear medicine in the diagnosis and/or treatment of tumors and abscesses. Comparative results with Ga-67-citrate, which is the most widely used tumor-localizing agent in nuclear medicine, indicate increased sensitivity of detection and greater tumor uptake with the Ru-transferrin complex. No Drawings

  10. Catalysis by Design: Bridging the Gap between Theory and Experiments...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Catalysis by Design: Bridging the Gap between Theory and Experiments Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 ...

  11. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis Print Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme...

  12. Center for Biological Electron Transfer and Catalysis (BETCy...

    Office of Science (SC) Website

    Research Topics solar (fuels), biofuels (including algae and biomass), bio-inspired, ... 5 GrandChallenge 2 Grand Challenge 2 BES Reports Catalysis Hydrogen Solar Energy

  13. Materials Design and Discovery: Catalysis and Energy Storage...

    Office of Scientific and Technical Information (OSTI)

    Materials Design and Discovery: Catalysis and Energy Storage (Mira Early Science Program Final Technical Report): ALCF-2 Early Science Program Technical Report Citation Details ...

  14. Control Heterogeneous Catalysis at Atomic and Electronic-level...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Control Heterogeneous Catalysis at Atomic and Electronic-level Using Intermetallic Compounds Precious metals and metal alloys are important heterogeneous catalysts for renewable...

  15. Catalysis by Design - Theoretical and Experimental Studies of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx Treatment Catalysis by Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx ...

  16. Catalysis | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Catalysis Basic Energy Sciences Advisory Committee (BESAC) BESAC Home Meetings Meeting Presentations History Logistics BESAC 2016-2017 Membership ChargesReports Charter .pdf file ...

  17. Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic

    Office of Scientific and Technical Information (OSTI)

    virus for micro-supercapacitors in solid Nafion electrolyte (Journal Article) | SciTech Connect Title: Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for micro-supercapacitors in solid Nafion electrolyte Authors: Gnerlich, Markus ; Ben-Yoav, Hadar ; Culver, James ; Ketchum, D ; Ghodssi, Reza Publication Date: 2015-10-01 OSTI Identifier: 1210848 DOE Contract Number: SC0001160 Resource Type: Journal Article Resource Relation: Journal Name: Journal of Power

  18. Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic

    Office of Scientific and Technical Information (OSTI)

    virus for micro-supercapacitors in solid Nafion electrolyte (Journal Article) | SciTech Connect This content will become publicly available on June 5, 2017 Title: Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for micro-supercapacitors in solid Nafion electrolyte Authors: Gnerlich, Markus Search SciTech Connect for author "Gnerlich, Markus" Search SciTech Connect for ORCID "0000000163589906" Search orcid.org for ORCID

  19. Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control PDF icon ...

  20. Ruthenium Behavior at Phase Separation of Borosilicate Glass-12259

    SciTech Connect (OSTI)

    Enokida, Youichi [Graduate School of Engineering, Nagoya University, Nagoya, 463-8603 (Japan); Sawada, Kayo [EcoTopia Science Institute, Nagoya University, Nagoya, 463-8603 (Japan)

    2012-07-01

    The Rokkasho reprocessing plant (RRP) located in Aomori, Japan, vitrifies high level waste (HLW) into a borosilicate glass. The HLW is generated from the reprocessing of spent fuel and contains ruthenium (Ru) and other platinum group metals (PGMs). Based on the recent consequences after a huge earthquake that occurred in Japan, a hypothetical blackout was postulated for the RRP to address additional safety analysis requirements. During a prolonged blackout, the borosilicate glass could phase separate due to cooling of the glass in the melter. The Ru present in the glass matrix could migrate into separate phases and impact the durability of the borosilicate glass. The durability of the glass is important for quality assurance and performance assessment of the vitrified HLW. A fundamental study was performed at an independent university to understand the impact of a prolonged blackout. Simulated HLW glasses were prepared for the RRP, and the Ru behavior in phase separated glasses was studied. The simulated HLW glasses contained nonradioactive elements and PGMs. The glass compositions were then altered to enhance the formation of the phase-separated glasses when subjected to thermal treatment at 700 deg. C for 24 hours. The synthesized simulated glasses contained 1.1 % Ru by weight as ruthenium dioxide (RuO{sub 2}). A portion of the RuO{sub 2} formed needle-shaped crystals in the glass specimens. After the thermal treatment, the glass specimen had separated into two phases. One of the two phases was a B{sub 2}O{sub 3} rich phase, and the other phase was a SiO{sub 2} rich phase. The majority of the chemical species in the B{sub 2}O{sub 3} rich phase was leached away with the Material Characterization Center-3 (MCC-3) protocol standardized by the Pacific Northwest National Laboratory using an aqueous low-concentrated nitric acid solution, but the leaching of the Ru fraction was very limited; less than 1% of the original Ru content. The Ru leaching was much less than those of the other elements, and the needle-shaped crystals of RuO{sub 2} were observed in the B{sub 2}O{sub 3} rich phase in the specimen after the leaching test. Another experiment was performed using another glass specimen which had been prepared with the same frits, but used reagent RuO{sub 2} of granular shape at lower content (0.0073% by weight as RuO{sub 2}). The leached fractions of elements for the latter specimen increased to almost the same fraction (more than 10% of the original Ru content) as observed for boron and sodium, when the phase separated glass was leached using the MMC-3 protocol with non-acidic de-ionized water. Based on the results of this study, it was concluded that needle-shaped RuO{sub 2} crystals are contained in the B{sub 2}O{sub 3}-rich phase after phase separation of the borosilicate glass after a hypothetical blackout. The leaching fraction for the needle-shaped RuO{sub 2} present in the phase separated glass is much lower than those for boron or sodium. Ruthenium behavior has been studied for a hypothetical loss of cooling in the liquid fed ceramic melter for high level waste by taking into account the phase separation of borosilicate glass. The needle-shaped crystal of ruthenium dioxide after bi-nodal-type phase separation of the borosilicate glass at 700 deg. C migrated into the B{sub 2}O{sub 3} rich phase, but remained without dissolution by an acidic aqueous solution. Additionally, granular ruthenium dioxide can be a morphological form of ruthenium after bimodal-type phase separation of the vitrified high level waste with borosilicate glass media. After the phase separation of the borosilicate glass, the crystal shape of the ruthenium dioxide is either needle-shaped or granular, and the leachable fraction of ruthenium is relatively much lower than those of major components (boron and sodium) in the vitrified borosilicate glass. The fraction of leached ruthenium increased to almost the same fraction as observed for boron and sodium when the phase-separated glass was leached with ultrapure water. (authors)

  1. Hydrodesulfurization of dibenzothiophene catalyzed by alumina-supported ruthenium carbonyl complexes in a pressurized flow system

    SciTech Connect (OSTI)

    NONE

    1994-11-01

    Ruthenium sulfide has been found to be most active for hydrodesulfurization (HDS) of thiophenes as well as hydrogenation and hydrodenitrogenation among transition metal sulfides. When ruthenium sulfide is supported on alumina, silica, or zeolite with high surface area, highly dispersed ruthenium sulfide formed on the supports would increase the catalytic activity per a ruthenium atom. Several researchers have already reported HDS using supported ruthenium sulfides. In these works [Ru(NH{sub 3}){sub 6}]{sup +}, Ru{sub 3}(CO){sub 12}, RuCl{sub 3}, and Ru(III) acetate supported on alumina, zeoliate, carbon, etc., were used as catalyst precursors in HDS of thiophene, benzothiophene, or dibenzothiophene. Although these HDS reactions were performed under an atmospheric pressure, the activity of the catalysts derived from supported ruthenium in a pressurized flow system have not yet been understood. In the present study, HDS of DBT catalyzed by ruthenium catalysts is investigated in a pressurized flow reactor. 17 refs., 2 figs., 2 tabs.

  2. Catalysis Working Group Kick-Off Meeting Agenda

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Arlington, VA - May 14, 2012 Catalysis Working Group Kick-off Meeting Co-Chairs: Piotr Zelenay Los Alamos National Laboratory Nancy L. Garland U.S. Department of Energy 2 2...

  3. Catalysis Working Group Kick-Off Meeting Agenda

    Broader source: Energy.gov [DOE]

    Agenda for the kick-off meeting of the U.S. Department of Energy Fuel Cell Technologies Program's Catalysis Working Group, held May 14, 2012, in Arlington, Virginia.

  4. Homogeneous and Interfacial Catalysis in 3D Controlled Environment | The

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Ames Laboratory Homogeneous and Interfacial Catalysis in 3D Controlled Environment FWP/Project Description: Project Leader(s): Marek Pruski Principal Investigators: Marek Pruski, Aaron Sadow, Igor Slowing Key Scientific Personnel: Takeshi Kobayashi This collaborative research effort is geared toward bringing together the best features of homogeneous and heterogeneous catalysis for developing new catalytic principles. Novel silica-based, single-site mesoporous catalysts with controlled,

  5. Materials Design and Discovery: Catalysis and Energy Storage (Mira Early

    Office of Scientific and Technical Information (OSTI)

    Science Program Final Technical Report): ALCF-2 Early Science Program Technical Report (Technical Report) | SciTech Connect Materials Design and Discovery: Catalysis and Energy Storage (Mira Early Science Program Final Technical Report): ALCF-2 Early Science Program Technical Report Citation Details In-Document Search Title: Materials Design and Discovery: Catalysis and Energy Storage (Mira Early Science Program Final Technical Report): ALCF-2 Early Science Program Technical Report Authors:

  6. Theoretical Study on Catalysis by Protein Enzymes and Ribozyme

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Theoretical Study on Catalysis by Protein Enzymes and Ribozyme Theoretical Study on Catalysis by Protein Enzymes and Ribozyme 2000 NERSC Annual Report 17shkarplus.jpg The energetics were determined for three mechanisms proposed for TIM catalyzed reactions. Results from reaction path calculations suggest that the two mechanisms that involve an enediol intermediate are likely to occur, while the direct intra-substrate proton transfer mechanism (in green) is energetically unfavorable due to the

  7. Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Make Fuels and Chemicals | Department of Energy Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make Fuels and Chemicals Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make Fuels and Chemicals BETO works with the emerging U.S. bioindustry to sustainably convert non-food biomass resources into cost-competitive biofuels, biopower, and bioproducts. PDF icon biochemical_four_pager.pdf More Documents & Publications Replacing the Whole

  8. Visualizing Group II Intron Catalysis through the Stages of Splicing

    Office of Scientific and Technical Information (OSTI)

    (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Visualizing Group II Intron Catalysis through the Stages of Splicing Citation Details In-Document Search Title: Visualizing Group II Intron Catalysis through the Stages of Splicing Authors: Marcia, Marco ; Pyle, Anna Marie [1] ; HHMI) [2] + Show Author Affiliations (Yale) ( Publication Date: 2013-01-10 OSTI Identifier: 1054354 Resource Type: Journal Article Resource Relation: Journal Name: Cell; Journal

  9. Outer sphere hydrogenation catalysis (Journal Article) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Outer sphere hydrogenation catalysis Citation Details In-Document Search Title: Outer sphere hydrogenation catalysis Authors: Eisenstein, Odile ; Crabtree, Robert H Publication Date: 2013-01-01 OSTI Identifier: 1080563 DOE Contract Number: SC0001055 Resource Type: Journal Article Resource Relation: Journal Name: New J. Chem.; Journal Volume: 37; Related Information: CETM partners with General Electric Global Research (lead); Lawrence Berkeley National Laboratory; Stanford University; Yale

  10. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis ALS X-Rays Shine a New Light on Catalysis Print Thursday, 21 May 2015 11:16 Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme sensitivity of their surface redox states to temperatures, to gas pressures, and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Recently a team of Stanford and Berkeley Lab

  11. Dedicated Beamline Facilities for Catalytic Research. Synchrotron Catalysis Consortium (SCC)

    SciTech Connect (OSTI)

    Chen, Jingguang; Frenkel, Anatoly; Rodriguez, Jose; Adzic, Radoslav; Bare, Simon R.; Hulbert, Steve L.; Karim, Ayman; Mullins, David R.; Overbury, Steve

    2015-03-04

    Synchrotron spectroscopies offer unique advantages over conventional techniques, including higher detection sensitivity and molecular specificity, faster detection rate, and more in-depth information regarding the structural, electronic and catalytic properties under in-situ reaction conditions. Despite these advantages, synchrotron techniques are often underutilized or unexplored by the catalysis community due to various perceived and real barriers, which will be addressed in the current proposal. Since its establishment in 2005, the Synchrotron Catalysis Consortium (SCC) has coordinated significant efforts to promote the utilization of cutting-edge catalytic research under in-situ conditions. The purpose of the current renewal proposal is aimed to provide assistance, and to develop new sciences/techniques, for the catalysis community through the following concerted efforts: Coordinating the implementation of a suite of beamlines for catalysis studies at the new NSLS-II synchrotron source; Providing assistance and coordination for catalysis users at an SSRL catalysis beamline during the initial period of NSLS to NSLS II transition; Designing in-situ reactors for a variety of catalytic and electrocatalytic studies; Assisting experimental set-up and data analysis by a dedicated research scientist; Offering training courses and help sessions by the PIs and co-PIs.

  12. Fibrillar dimer formation of islet amyloid polypeptides

    SciTech Connect (OSTI)

    Chiu, Chi -cheng; de Pablo, Juan J.

    2015-05-08

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimental and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.

  13. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOE Patents [OSTI]

    Pierantozzi, R.

    1985-04-09

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  14. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOE Patents [OSTI]

    Pierantozzi, R.

    1985-04-02

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  15. Preparation of olefins from synthesis gas using ruthenium supported on ceric oxide

    DOE Patents [OSTI]

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  16. Ruthenium carbonyl catalyst supported on ceric oxide for preparation of olefins from synthesis gas

    DOE Patents [OSTI]

    Pierantozzi, Ronald

    1985-01-01

    A catalyst comprising a ruthenium carbonyl compound deposited on a cerium oxide-containing support material provides for the selective synthesis of low molecular weight olefinic hydrocarbons from mixtures of hydrogen and carbon monoxide.

  17. Platinum-ruthenium-palladium alloys for use as a fuel cell catalyst

    DOE Patents [OSTI]

    Gorer, Alexander

    2002-01-01

    A noble metal alloy composition for a fuel cell catalyst, a ternary alloy composition containing platinum, ruthenium and palladium. The alloy shows increased activity as compared to well-known catalysts.

  18. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    DOE Patents [OSTI]

    Corbea, Javier Jesus Concepcion; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L.; Hoertz, Paul; Meyer, Thomas J.

    2013-09-03

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  19. Ruthenium or osmium complexes and their uses as catalysts for water oxidation

    DOE Patents [OSTI]

    Concepcion Corbea, Javier Jesus; Chen, Zuofeng; Jurss, Jonah Wesley; Templeton, Joseph L; Hoertz, Paul; Meyer, Thomas J

    2014-10-28

    The present invention provides ruthenium or osmium complexes and their uses as a catalyst for catalytic water oxidation. Another aspect of the invention provides an electrode and photo-electrochemical cells for electrolysis of water molecules.

  20. Characterization of Palladium and Ruthenium after Reaction with Tetraphenylborate and Mercury

    SciTech Connect (OSTI)

    Duff, M.C.

    2001-09-11

    This report documents a second series of X-ray fine structure and chemical analyses to examine the form that Pd - and, to a lesser extent, ruthenium (Ru) - takes in simulated high-level slurries containing TPB salts.

  1. Ruthenium on rutile catalyst, catalytic system, and method for aqueous phase hydrogenations

    DOE Patents [OSTI]

    Elliot, Douglas C.; Werpy, Todd A.; Wang, Yong; Frye, Jr., John G.

    2001-01-01

    An essentially nickel- and rhenium-free catalyst is described comprising ruthenium on a titania support where the titania is greater than 75% rutile. A catalytic system containing a nickel-free catalyst comprising ruthenium on a titania support where the titania is greater than 75% rutile, and a method using this catalyst in the hydrogenation of an organic compound in the aqueous phase is also described.

  2. Some General Themes in Catalysis at LANL

    SciTech Connect (OSTI)

    Gordon, John C.

    2012-07-19

    Some general themes in catalysis at LANL are: (1) Storage and release of energy within chemical bonds (e.g. H{sub 2} storage in and release from covalent bonds, N{sub 2} functionalization, CO{sub 2} functionalization, H{sub 2} oxidation/evolution, O{sub 2} reduction/evolution); (2) Can we control the chemistry of reactive substrates to effect energy relevant transformations in non-traditional media (e.g. can we promote C-C couplings, dehydrations, or hydrogenations in water under relatively mild conditions)? (3) Can we supplant precious metal or rare earth catalysts to effect these transformations, by using earth abundant metals/elements instead? Can we use organocatalysis and circumvent the use of metals completely? (4) Can we improve upon existing rare earth catalyst systems (e.g. in rare earth oxides pertinent to fluid cracking or polymerization) and reduce amounts required for catalytic efficacy? Carbohydrates can be accessed from non-food based biomass sources such as woody residues and switchgrass. After extracted from the plant source, our goal is to upgrade these classes of molecules into useful fuels.

  3. Size Effect of Ruthenium Nanoparticles in Catalytic Carbon Monoxide Oxidation

    SciTech Connect (OSTI)

    Joo, Sang Hoon; Park, Jeong Y.; Renzas, J. Russell; Butcher, Derek R.; Huang, Wenyu; Somorjai, Gabor A.

    2010-04-04

    Carbon monoxide oxidation over ruthenium catalysts has shown an unusual catalytic behavior. Here we report a particle size effect on CO oxidation over Ru nanoparticle (NP) catalysts. Uniform Ru NPs with a tunable particle size from 2 to 6 nm were synthesized by a polyol reduction of Ru(acac){sub 3} precursor in the presence of poly(vinylpyrrolidone) stabilizer. The measurement of catalytic activity of CO oxidation over two-dimensional Ru NPs arrays under oxidizing reaction conditions (40 Torr CO and 100 Torr O{sub 2}) showed an activity dependence on the Ru NP size. The CO oxidation activity increases with NP size, and the 6 nm Ru NP catalyst shows 8-fold higher activity than the 2 nm catalysts. The results gained from this study will provide the scientific basis for future design of Ru-based oxidation catalysts.

  4. Platinum adlayered ruthenium nanoparticles, method for preparing, and uses thereof

    DOE Patents [OSTI]

    Tong, YuYe; Du, Bingchen

    2015-08-11

    A superior, industrially scalable one-pot ethylene glycol-based wet chemistry method to prepare platinum-adlayered ruthenium nanoparticles has been developed that offers an exquisite control of the platinum packing density of the adlayers and effectively prevents sintering of the nanoparticles during the deposition process. The wet chemistry based method for the controlled deposition of submonolayer platinum is advantageous in terms of processing and maximizing the use of platinum and can, in principle, be scaled up straightforwardly to an industrial level. The reactivity of the Pt(31)-Ru sample was about 150% higher than that of the industrial benchmark PtRu (1:1) alloy sample but with 3.5 times less platinum loading. Using the Pt(31)-Ru nanoparticles would lower the electrode material cost compared to using the industrial benchmark alloy nanoparticles for direct methanol fuel cell applications.

  5. Solvation and Acid Strength Effects on Catalysis by Faujasite Zeolites

    SciTech Connect (OSTI)

    Gounder, Rajamani P.; Jones, Andrew J.; Carr, Robert T.; Iglesia, Enrique

    2012-02-01

    Kinetic, spectroscopic, and chemical titration data indicate that differences in monomolecular isobutane cracking and dehydrogenation and methanol dehydration turnover rates (per H+) among FAU zeolites treated thermally with steam (H-USY) and then chemically with ammonium hexafluorosilicate (CDHUSY) predominantly reflect differences in the size and solvating properties of their supercage voids rather than differences in acid strength. The number of protons on a given sample was measured consistently by titrations with Na+, with CH3 groups via reactions of dimethyl ether, and with 2,6-di-tert-butylpyridine during methanol dehydration catalysis; these titration values were also supported by commensurate changes in acidic OH infrared band areas upon exposure to titrant molecules. The number of protons, taken as the average of the three titration methods, was significantly smaller than the number of framework Al atoms (Alf) obtained from X-ray diffraction and 27Al magic angle spinning nuclear magnetic resonance spectroscopy on H-USY (0.35 H+/Alf) and CD-HUSY (0.69 H+/Alf). These data demonstrate that the ubiquitous use of Alf sites as structural proxies for active H+ sites in zeolites can be imprecise, apparently because distorted Al structures that are not associated with acidic protons are sometimes detected as Alf sites. Monomolecular isobutane cracking and dehydrogenation rate constants, normalized non-rigorously by the number of Alf species, decreased with increasing Na+ content on both H-USY and CD-HUSY samples and became undetectable at sub-stoichiometric exchange levels (0.32 and 0.72 Na+/Alf ratios, respectively), an unexpected finding attributed incorrectly in previous studies to the presence of minority ‘‘super-acidic’’ sites. These rate constants, when normalized rigorously by the number of residual H+ sites were independent of Na+ content on both H-USY and CD-HUSY samples, reflecting the stoichiometric replacement of protons that are uniform in reactivity by Na+ cations. Monomolecular isobutane cracking and dehydrogenation rate constants (per H+; 763 K), however, were higher on H-USY than CD-HUSY (by a factor of 1.4). Equilibrium constants for the formation of protonated methanol dimers via adsorption of gaseous methanol onto adsorbed methanol monomers, determined from kinetic studies of methanol dehydration to dimethyl ether (433 K), were also higher on H-USY than CD-HUSY (by a factor of 2.1). These larger constants predominantly reflect stronger dispersive interactions in H-USY, consistent with its smaller supercage voids that result from the occlusion of void space by extraframework Al (Alex) residues. These findings appear to clarify enduring controversies about the mechanistic interpretation of the effects of Na+ and Alex species on the catalytic reactivity of FAU zeolites. They also illustrate the need to normalize rates by the number of active sites instead of more convenient but less accurate structural proxies for such sites.

  6. Center for Catalysis at Iowa State University

    SciTech Connect (OSTI)

    Kraus, George A.

    2006-10-17

    The overall objective of this proposal is to enable Iowa State University to establish a Center that enjoys world-class stature and eventually enhances the economy through the transfer of innovation from the laboratory to the marketplace. The funds have been used to support experimental proposals from interdisciplinary research teams in areas related to catalysis and green chemistry. Specific focus areas included: Catalytic conversion of renewable natural resources to industrial materials Development of new catalysts for the oxidation or reduction of commodity chemicals Use of enzymes and microorganisms in biocatalysis Development of new, environmentally friendly reactions of industrial importance These focus areas intersect with barriers from the MYTP draft document. Specifically, section 2.4.3.1 Processing and Conversion has a list of bulleted items under Improved Chemical Conversions that includes new hydrogenation catalysts, milder oxidation catalysts, new catalysts for dehydration and selective bond cleavage catalysts. Specifically, the four sections are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D) All funded projects are part of a soybean or corn biorefinery. Two funded projects that have made significant progress toward goals of the MYTP draft document are: Catalysts to convert feedstocks with high fatty acid content to biodiesel (Kraus, Lin, Verkade) and Conversion of Glycerol into 1,3-Propanediol (Lin, Kraus). Currently, biodiesel is prepared using homogeneous base catalysis. However, as producers look for feedstocks other than soybean oil, such as waste restaurant oils and rendered animal fats, they have observed a large amount of free fatty acids contained in the feedstocks. Free fatty acids cannot be converted into biodiesel using homogeneous base-mediated processes. The CCAT catalyst system offers an integrated and cooperative catalytic system that performs both esterification (of free fatty acids) and transesterification (of soybean oil) in a one-pot fashion. This will allow the biodiesel producers to use the aforementioned cheap feedstocks without any pretreatment. In addition, the catalyst system is heterogeneous and is highly recyclable and reusable. Although markets currently exist for glycerin, concern is mounting that the price of glycerin may plummet to $.05 - $.10 per pound if future production exceeds demand. Developing a system to make high value chemicals such as 1,3-propanediol from the glycerin stream will add value for biodiesel producers who implement the new technology. Given the fact that both DuPont and Shell chemicals have announced the commercialization of two new PDO-based polymers, a rapid increase of market demand for a cheaper PDO source is very likely. 4. Comparison of actual accomplishments with goals and objectives From our progress reports, the four areas are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D)

  7. Equivalence between XY and dimerized models

    SciTech Connect (OSTI)

    Campos Venuti, Lorenzo; Roncaglia, Marco

    2010-06-15

    The spin-1/2 chain with XY anisotropic coupling in the plane and the XX isotropic dimerized chain are shown to be equivalent in the bulk. For finite systems, we prove that the equivalence is exact in given parity sectors, after taking care of the precise boundary conditions. The proof is given constructively by finding unitary transformations that map the models onto each other. Moreover, we considerably generalized our mapping and showed that even in the case of fully site-dependent couplings the XY chain can be mapped onto an XX model. This result has potential application in the study of disordered systems.

  8. Development of a stable cobalt-ruthenium Fisher-Tropsch catalyst. Final report

    SciTech Connect (OSTI)

    Frame, R.R.; Gala, H.B.

    1995-02-01

    The reverse micelle catalyst preparation method has been used to prepare catalysts on four supports: magnesium oxide, carbon, alumina- titania and steamed Y zeolite. These catalysts were not as active as a reference catalyst prepared during previous contracts to Union Carbide Corp. This catalyst was supported on steamed Y zerolite support and was impregnated by a pore-filling method using a nonaqueous solvent. Additional catalysts were prepared via pore- filling impregnation of steamed Y zeolites. These catalysts had levels of cobalt two to three and a half times as high as the original Union Carbide catalyst. On a catalyst volume basis they were much more active than the previous catalyst; on an atom by atom basis the cobalt was about of the same activity, i.e., the high cobalt catalysts` cobalt atoms were not extensively covered over and deactivated by other cobalt atoms. The new, high activity, Y zerolite catalysts were not as stable as the earlier Union Carbide catalyst. However, stability enhancement of these catalysts should be possible, for instance, through adjustment of the quantity and/or type of trace metals present. A primary objective of this work was determination whether small amounts of ruthenium could enhance the activity of the cobalt F-T catalyst. The reverse micelle catalysts were not activated by ruthenium, indeed scanning transmission electronic microscopy (STEM) analysis provided some evidence that ruthenium was not present in the cobalt crystallites. Ruthenium did not seem to activate the high cobalt Y zeolite catalyst either, but additional experiments with Y zeolite-supported catalysts are required. Should ruthenium prove not to be an effective promoter under the simple catalyst activation procedure used in this work, more complex activation procedures have been reported which are claimed to enhance the cobalt/ruthenium interaction and result in activity promotion by ruthenium.

  9. Structural bases of dimerization of yeast telomere protein Cdc13...

    Office of Scientific and Technical Information (OSTI)

    polymerase alpha (Pol1), and demonstrated a role for Cdc13 dimerization in Pol1 binding. ... Country of Publication: United States Language: ENGLISH Subject: 59 BASIC BIOLOGICAL ...

  10. Evidence for Phenylalanine Zipper-Mediated Dimerization in the...

    Office of Scientific and Technical Information (OSTI)

    Evidence for Phenylalanine Zipper-Mediated Dimerization in the X-ray Crystal Structure of a Magainin 2 Analogue Citation Details In-Document Search Title: Evidence for ...

  11. Fibrillar dimer formation of islet amyloid polypeptides

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chiu, Chi -cheng; de Pablo, Juan J.

    2015-05-08

    Amyloid deposits of human islet amyloid polypeptide (hIAPP), a 37-residue hormone co-produced with insulin, have been implicated in the development of type 2 diabetes. Residues 20 – 29 of hIAPP have been proposed to constitute the amyloidogenic core for the aggregation process, yet the segment is mostly unstructured in the mature fibril, according to solid-state NMR data. Here we use molecular simulations combined with bias-exchange metadynamics to characterize the conformational free energies of hIAPP fibrillar dimer and its derivative, pramlintide. We show that residues 20 – 29 are involved in an intermediate that exhibits transient β-sheets, consistent with recent experimentalmore » and simulation results. By comparing the aggregation of hIAPP and pramlintide, we illustrate the effects of proline residues on inhibition of the dimerization of IAPP. The mechanistic insights presented here could be useful for development of therapeutic inhibitors of hIAPP amyloid formation.« less

  12. Study of catalysis of coal gasification at elevated pressures. [Evaluation

    Office of Scientific and Technical Information (OSTI)

    of 20 compounds at 850/sup 0/C] (Journal Article) | SciTech Connect Study of catalysis of coal gasification at elevated pressures. [Evaluation of 20 compounds at 850/sup 0/C] Citation Details In-Document Search Title: Study of catalysis of coal gasification at elevated pressures. [Evaluation of 20 compounds at 850/sup 0/C] Authors: Haynes, W.P. ; Neilson, H. [1] ; Field, J.H. + Show Author Affiliations (US Bur. Mines, Pittsburgh, PA) Publication Date: 1971-01-01 OSTI Identifier: 5238924

  13. Seventh BES (Basic Energy Sciences) catalysis and surface chemistry research conference

    SciTech Connect (OSTI)

    Not Available

    1990-03-01

    Research programs on catalysis and surface chemistry are presented. A total of fifty-seven topics are included. Areas of research include heterogeneous catalysis; catalysis in hydrogenation, desulfurization, gasification, and redox reactions; studies of surface properties and surface active sites; catalyst supports; chemical activation, deactivation; selectivity, chemical preparation; molecular structure studies; sorption and dissociation. Individual projects are processed separately for the data bases. (CBS)

  14. Development of carbon-metal oxide supercapacitors from sol-gel derived carbon-ruthenium xerogels

    SciTech Connect (OSTI)

    Lin, C.; Ritter, J.A.; Popov, B.N.

    1999-09-01

    There has been increasing interest in electrochemical capacitors as energy storage systems because of their high power density and long cycle life, compared to battery devices. According to the mechanism of energy storage, there are two types of electrochemical capacitors. One type is based on double layer (dl) formation due to charge separation, and the other type is based on a faradaic process due to redox reactions. Sol-gel derived high surface area carbon-ruthenium xerogels were prepared from carbonized resorcinol-formaldehyde resins containing an electrochemically active form of ruthenium oxide. The electrochemical capacitance of these materials increased with an increase in the ruthenium content indicating the presence of pseudocapacitance associated with the ruthenium oxide undergoing reversible faradaic redox reactions. A specific capacitance of 256 F/g (single electrode) was obtained from a carbon xerogel containing 14 wt% Ru, which corresponded to more than 50% utilization of the ruthenium. The double layer accounted for 40% of this capacitance. This material was also electrochemically stable, showing no change in a cyclic voltammogram for over 2,000 cycles.

  15. Simulations of Cellulose Translocation in the Bacterial Cellulose Synthase Suggest a Regulatory Mechanism for the Dimeric Structure of Cellulose

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Knott, Brandon C.; Crowley, Michael F.; Himmel, Michael E.; Zimmer, Jochen; Beckham, Gregg T.

    2016-05-01

    The processive cycle of the bacterial cellulose synthase (Bcs) includes the addition of a single glucose moiety to the end of a growing cellulose chain followed by the translocation of the nascent chain across the plasma membrane. The mechanism of this translocation and its precise location within the processive cycle are not well understood. In particular, the molecular details of how a polymer (cellulose) whose basic structural unit is a dimer (cellobiose) can be constructed by adding one monomer (glucose) at a time are yet to be elucidated. Here, we have utilized molecular dynamics simulations and free energy calculations tomore » the shed light on these questions. We find that translocation forward by one glucose unit is quite favorable energetically, giving a free energy stabilization of greater than 10 kcal mol-1. In addition, there is only a small barrier to translocation, implying that translocation is not rate limiting within the Bcs processive cycle (given experimental rates for cellulose synthesis in vitro). Perhaps most significantly, our results also indicate that steric constraints at the transmembrane tunnel entrance regulate the dimeric structure of cellulose. Namely, when a glucose molecule is added to the cellulose chain in the same orientation as the acceptor glucose, the terminal glucose freely rotates upon forward motion, thus suggesting a regulatory mechanism for the dimeric structure of cellulose. We characterize both the conserved and non-conserved enzyme-polysaccharide interactions that drive translocation, and find that 20 of the 25 residues that strongly interact with the translocating cellulose chain in the simulations are well conserved, mostly with polar or aromatic side chains. Our results also allow for a dynamical analysis of the role of the so-called 'finger helix' in cellulose translocation that has been observed structurally. Taken together, these findings aid in the elucidation of the translocation steps of the Bcs processive cycle and may be widely relevant to polysaccharide synthesizing or degrading enzymes that couple catalysis with chain translocation.« less

  16. Molecular-Level Design of Heterogeneous Chiral Catalysis

    SciTech Connect (OSTI)

    Francisco Zaera

    2012-03-21

    The following is a proposal to continue our multi-institutional research on heterogeneous chiral catalysis. Our team combines the use of surface-sensitive analytical techniques for the characterization of model systems with quantum and statistical mechanical calculations to interpret experimental data and guide the design of future research. Our investigation focuses on the interrelation among the three main mechanisms by which enantioselectivity can be bestowed to heterogeneous catalysts, namely: (1) by templating chirality via the adsorption of chiral supramolecular assemblies, (2) by using chiral modifiers capable of forming chiral complexes with the reactant and force enantioselective surface reactions, and (3) by forming naturally chiral surfaces using imprinting chiral agents. Individually, the members of our team are leaders in these various aspects of chiral catalysis, but the present program provides the vehicle to generate and exploit the synergies necessary to address the problem in a comprehensive manner. Our initial work has advanced the methodology needed for these studies, including an enantioselective titration procedure to identify surface chiral sites, infrared spectroscopy in situ at the interface between gases or liquids and solids to mimic realistic catalytic conditions, and DFT and Monte Carlo algorithms to simulate and understand chirality on surfaces. The next step, to be funded by the monies requested in this proposal, is to apply those methods to specific problems in chiral catalysis, including the identification of the requirements for the formation of supramolecular surface structures with enantioselective behavior, the search for better molecules to probe the chiral nature of the modified surfaces, the exploration of the transition from supramolecular to one-to-one chiral modification, the correlation of the adsorption characteristics of one-to-one chiral modifiers with their physical properties, in particular with their configuration, and the development of ways to imprint chiral centers on achiral solid surfaces. Chiral catalysis is not only a problem of great importance in its own right, but also the ultimate test of how to control selectivity in catalysis. The time is ripe for fundamental work in heterogeneous chiral catalysis to provide the U.S. with a leadership role in developing the next generation of catalytic processes for medicinal and agrochemical manufacturing. Our team provides the required expertise for a synergistic and comprehensive integration of physical and chemical experimentation with solid state and molecular reactivity theories to solve this problem.

  17. Adsorption of silver dimer on graphene - A DFT study

    SciTech Connect (OSTI)

    Kaur, Gagandeep, E-mail: gaganj1981@yahoo.com [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and Chandigarh Engineering College, Landran, Mohali-140307, Punjab (India); Gupta, Shuchi [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014, India and University Institute of Engineering and Technology, Panjab University, Chandigarh -160014 (India); Rani, Pooja; Dharamvir, Keya [Department of Physics and Centre of Advanced Studies in Physics, Panjab University, Chandigarh-160014 (India)

    2014-04-24

    We performed a systematic density functional theory (DFT) study of the adsorption of silver dimer (Ag{sub 2}) on graphene using SIESTA (Spanish Initiative for Electronic Simulations with Thousands of Atoms) package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Ag2-graphene system are calculated. The minimum energy configuration for a silver dimer is parallel to the graphene sheet with its two atoms directly above the centre of carbon-carbon bond. The negligible charge transfer between the dimer and the surface is also indicative of a weak bond. The methodology demonstrated in this paper may be applied to larger silver clusters on graphene sheet.

  18. SEPARATION OF URANYL AND RUTHENIUM VALUES BY THE TRIBUTYL PHOSPHATE EXTRACTION PROCESS

    DOE Patents [OSTI]

    Wilson, A.S.

    1961-05-01

    A process is given for separating uranyl values from ruthenium values contained in an aqueous 3 to 4 M nitric acid solution. After the addition of hydrogen peroxide to obtain a concentration of 0.3 M, the uranium is selectively extracted with kerosene-diluted tributyl phosphate.

  19. Method for producing electricity using a platinum-ruthenium-palladium catalyst in a fuel cell

    DOE Patents [OSTI]

    Gorer, Alexander

    2004-01-27

    A method for producing electricity using a fuel cell that utilizes a ternary alloy composition as a fuel cell catalyst, the ternary alloy composition containing platinum, ruthenium and palladium. The alloy shows increased activity as compared to well-known catalysts.

  20. Effects of ruthenium seed layer on the microstructure and spin dynamics of thin permalloy films

    SciTech Connect (OSTI)

    Jin Lichuan; Zhang Huaiwu; Tang Xiaoli; Bai Feiming; Zhong Zhiyong

    2013-02-07

    The spin dynamics and microstructure properties of a sputtered 12 nm Ni{sub 81}Fe{sub 19} thin film have been enhanced by the use of a ruthenium seed layer. Both the ferromagnetic resonance field and linewidth are enhanced dramatically as the thickness of ruthenium seed layer is increased. The surface anisotropy energy constant can also be largely tailored from 0.06 to 0.96 erg/cm{sup -2} by changing the seed layer thickness. The changes to the dynamics magnetization properties are caused by both ruthenium seed layer induced changes in the Ni{sub 81}Fe{sub 19} structure properties and surface topography properties. Roughness induced inhomogeneous linewidth broadening is also seen. The damping constant is highly tunable via the ruthenium thickness. This approach can be used to tailor both the structure and spin dynamic properties of thin Ni{sub 81}Fe{sub 19} films over a wide range. And it may benefit the applications of spin dynamics and spin current based devices.

  1. Recent advances of lanthanum-based perovskite oxides for catalysis

    SciTech Connect (OSTI)

    Zhu, Huiyuan; Zhang, Pengfei; Dai, Sheng

    2015-09-21

    There is a need to reduce the use of noble metal elements especially in the field of catalysis, where noble metals are ubiquitously applied. To this end, perovskite oxides, an important class of mixed oxide, have been attracting increasing attention for decades as potential replacements. Benefiting from the extraordinary tunability of their compositions and structures, perovskite oxides can be rationally tailored and equipped with targeted physical and chemical properties e.g. redox behavior, oxygen mobility, and ion conductivity for enhanced catalysis. Recently, the development of highly efficient perovskite oxide catalysts has been extensively studied. This review article summarizes the recent development of lanthanum-based perovskite oxides as advanced catalysts for both energy conversion applications and traditional heterogeneous reactions.

  2. Recent advances of lanthanum-based perovskite oxides for catalysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Zhu, Huiyuan; Zhang, Pengfei; Dai, Sheng

    2015-09-21

    There is a need to reduce the use of noble metal elements especially in the field of catalysis, where noble metals are ubiquitously applied. To this end, perovskite oxides, an important class of mixed oxide, have been attracting increasing attention for decades as potential replacements. Benefiting from the extraordinary tunability of their compositions and structures, perovskite oxides can be rationally tailored and equipped with targeted physical and chemical properties e.g. redox behavior, oxygen mobility, and ion conductivity for enhanced catalysis. Recently, the development of highly efficient perovskite oxide catalysts has been extensively studied. This review article summarizes the recent developmentmore » of lanthanum-based perovskite oxides as advanced catalysts for both energy conversion applications and traditional heterogeneous reactions.« less

  3. Iron Catalysis in Oxidations by Ozone - Energy Innovation Portal

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Find More Like This Return to Search Iron Catalysis in Oxidations by Ozone Ames Laboratory Contact AMES About This Technology Technology Marketing Summary Ozone is used commercially for treatment of potable and non-potable water, and as an industrial oxidant. ISU and Ames Laboratory researchers have developed a method for using iron in ozone oxidation that significantly improves the speed of oxidation reactions. Description Ozone is recognized as potent and effective oxidizing agent, and has a

  4. ECIS and Compass Metals: Platinum Nanostructures for Enhanced Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ECIS and Compass Metals: Platinum Nanostructures for Enhanced Catalysis - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary Power Energy Conversion Efficiency Solar Energy Wind Energy Water Power Supercritical CO2 Geothermal Natural Gas Safety, Security & Resilience of the Energy Infrastructure Energy Storage Nuclear Power & Engineering Grid Modernization Battery Testing Nuclear Fuel

  5. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis Print Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme sensitivity of their surface redox states to temperatures, to gas pressures, and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Recently a team of Stanford and Berkeley Lab researchers used x-rays at the ALS in a novel way to observe the behavior of

  6. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis Print Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme sensitivity of their surface redox states to temperatures, to gas pressures, and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Recently a team of Stanford and Berkeley Lab researchers used x-rays at the ALS in a novel way to observe the behavior of

  7. University of Delaware | Catalysis Center for Energy Innovation | Modeling

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Modeling Activity map produced from the new high-throughput computational engine. Example for ethylene glycol catalysis. Reforming, hydrodeoxygenation, dehydrogenation, and catalyst poisoning (e.g., coking) occur at different regions of the map. Major developments have taken place in first-principles-based prediction of reforming and hydrodeoxygenation catalysts for key biomass derivatives. These developments can eventually assist in catalyst and process design for bio-oil upgrade and conversion

  8. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis Print Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme sensitivity of their surface redox states to temperatures, to gas pressures, and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Recently a team of Stanford and Berkeley Lab researchers used x-rays at the ALS in a novel way to observe the behavior of

  9. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis Print Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme sensitivity of their surface redox states to temperatures, to gas pressures, and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Recently a team of Stanford and Berkeley Lab researchers used x-rays at the ALS in a novel way to observe the behavior of

  10. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis Print Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme sensitivity of their surface redox states to temperatures, to gas pressures, and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Recently a team of Stanford and Berkeley Lab researchers used x-rays at the ALS in a novel way to observe the behavior of

  11. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    ALS X-Rays Shine a New Light on Catalysis Print Electrocatalysts are responsible for expediting reactions in many promising renewable energy technologies. However, the extreme sensitivity of their surface redox states to temperatures, to gas pressures, and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Recently a team of Stanford and Berkeley Lab researchers used x-rays at the ALS in a novel way to observe the behavior of

  12. Catalysis by Design - Theoretical and Experimental Studies of Model

    Broader source: Energy.gov (indexed) [DOE]

    Catalysis Working Group (CWG) meets twice per year to exchange information, create synergies, and collaboratively develop both an understanding of and tools for studying electrocatalysis for polymer electrolyte fuel cells (PEFCs) and other low- and intermediate-temperature fuel cell systems, including direct methanol fuel cells (DMFCs), alkaline fuel cells (AFCs), alkaline membrane fuel cells (AMFCs), and phosphoric acid fuel cells (PAFCs). The CWG members include principal and co-principal

  13. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    SciTech Connect (OSTI)

    Hartwig, J.F.

    1990-12-01

    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe{sub 3}){sub 4}Ru(X)(Y) and (DMPM){sub 2}Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe{sub 3}){sub 4}Ru(Ph)(Me) or (PMe{sub 3}){sub 4}Ru(Ph){sub 2} leads to the ruthenium benzyne complex (PMe{sub 3}){sub 4}Ru({eta}{sup 2}-C{sub 6}H{sub 4}) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO{sub 2} and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe{sub 3}){sub 4}Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs.

  14. Simulating Ru L3-Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    SciTech Connect (OSTI)

    Kuiken, Benjamin E. Van; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-04-26

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  15. EERE Success Story-Fundamental Studies in Catalysis Enabled the use of

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Efficient "Lean-Burn" Engines for Vehicle Transportation | Department of Energy Fundamental Studies in Catalysis Enabled the use of Efficient "Lean-Burn" Engines for Vehicle Transportation EERE Success Story-Fundamental Studies in Catalysis Enabled the use of Efficient "Lean-Burn" Engines for Vehicle Transportation May 7, 2015 - 1:29pm Addthis Building on a catalysis research program sponsored by EERE's Vehicles Technology Office (VTO) and DOE's Office of

  16. Virtual special issue on catalysis at the U.S. Department of Energy's National Laboratories

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Pruski, Marek; Sadow, Aaron D.; Slowing, Igor I.; Marshall, Christopher L.; Stair, Peter; Rodriguez, Jose; Harris, Alex; Somorjai, Gabor A.; Biener, Juergen; Matranga, Christopher; et al

    2016-04-21

    Here the catalysis research at the U.S. Department of Energy's (DOE's) National Laboratories covers a wide range of research topics in heterogeneous catalysis, homogeneous/molecular catalysis, biocatalysis, electrocatalysis, and surface science. Since much of the work at National Laboratories is funded by DOE, the research is largely focused on addressing DOE's mission to ensure America's security and prosperity by addressing its energy, environmental, and nuclear challenges through transformative science and technology solutions.

  17. Analyses of Candida Cdc13 Orthologues Revealed a Novel OB Fold Dimer

    Office of Scientific and Technical Information (OSTI)

    Arrangement, Dimerization-Assisted DNA Binding, and Substantial Structural Differences between Cdc13 and RPA70 (Journal Article) | SciTech Connect Analyses of Candida Cdc13 Orthologues Revealed a Novel OB Fold Dimer Arrangement, Dimerization-Assisted DNA Binding, and Substantial Structural Differences between Cdc13 and RPA70 Citation Details In-Document Search Title: Analyses of Candida Cdc13 Orthologues Revealed a Novel OB Fold Dimer Arrangement, Dimerization-Assisted DNA Binding, and

  18. Selective catalytic reduction system and process for treating NOx emissions using a palladium and rhodium or ruthenium catalyst

    DOE Patents [OSTI]

    Sobolevskiy, Anatoly; Rossin, Joseph A.; Knapke, Michael J.

    2011-07-12

    A process for the catalytic reduction of nitrogen oxides (NOx) in a gas stream (29) in the presence of H.sub.2 is provided. The process comprises contacting the gas stream with a catalyst system (38) comprising zirconia-silica washcoat particles (41), a pre-sulfated zirconia binder (44), and a catalyst combination (40) comprising palladium and at least one of rhodium, ruthenium, or a mixture of ruthenium and rhodium.

  19. Highly stable tetrathiafulvalene radical dimers in [3]catenanes

    SciTech Connect (OSTI)

    Spruell, Jason M.; Coskun, Ali; Friedman, Douglas C.; Forgan, Ross S.; Sarjeant, Amy A.; Trabolsi, Ali; Fahrenbach, Albert C.; Barin, Gokhan; Paxton, Walter F.; Dey, Sanjeev K.; Olson, Mark A.; Bentez, Diego; Tkatchouk, Ekaterina; Colvin, Michael T.; Carmielli, Raanan; Caldwell, Stuart T.; Rosair, Georgina M.; Hewage, Shanika Gunatilaka; Duclairoir, Florence; Seymour, Jennifer L.; Slawin, Alexandra M.Z.; Goddard, III, William A.; Wasielewski, Michael R.; Cooke, Graeme; Stoddart, J. Fraser

    2010-12-03

    Two [3]catenane 'molecular flasks' have been designed to create stabilized, redox-controlled tetrathiafulvalene (TTF) dimers, enabling their spectrophotometric and structural properties to be probed in detail. The mechanically interlocked framework of the [3]catenanes creates the ideal arrangement and ultrahigh local concentration for the encircled TTF units to form stable dimers associated with their discrete oxidation states. These dimerization events represent an affinity umpolung, wherein the inversion in electronic affinity replaces the traditional TTF-bipyridinium interaction, which is over-ridden by stabilizing mixed-valence (TTF){sub 2}{sup {sm_bullet}+} and radical-cation (TTF{sup {sm_bullet}+}){sub 2} states inside the 'molecular flasks.' The experimental data, collected in the solid state as well as in solution under ambient conditions, together with supporting quantum mechanical calculations, are consistent with the formation of stabilized paramagnetic mixed-valence dimers, and then diamagnetic radical-cation dimers following subsequent one-electron oxidations of the [3]catenanes.

  20. Palladium dimers adsorbed on graphene: A DFT study

    SciTech Connect (OSTI)

    Kaur, Gagandeep; Gupta, Shuchi; Dharamvir, Keya

    2015-05-15

    The 2D structure of graphene shows a great promise for enhanced catalytic activity when adsorbed with palladium. We performed a systematic density functional theory (DFT) study of the adsorption of palladium dimer (Pd{sub 2}) on graphene using SIESTA package, in the generalized gradient approximation (GGA). The adsorption energy, geometry, and charge transfer of Pd{sub 2}-graphene system are calculated. Both horizontal and vertical orientations of Pd{sub 2} on graphene are studied. Our calculations revealed that the minimum energy configuration for Pd dimer is parallel to the graphene sheet with its two atoms occupying centre of adjacent hexagonal rings of graphene sheet. Magnetic moment is induced for Pd dimer adsorbed on graphene in vertical orientation while horizontal orientation of Pd dimer on graphene do not exhibit magnetism. Insignificant energy differences among adsorption sites means that dimer mobility on the graphene sheet is high. There is imperceptible distortion of graphene sheet perpendicular to its plane. However, some lateral displacements are seen.

  1. Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles

    SciTech Connect (OSTI)

    Maiti, A; Gee, R H; Maxwell, R; Saab, A

    2007-02-01

    Prompted by the need for a self-supported, chemically stable, and functionally flexible catalytic nanoparticle system, we explore a system involving Pd clusters coated with a monolayer of polyhedral oligomeric silsesquioxane (POSS) cages. With an initial theoretical focus on hydrogen catalysis and sequestration in the Pd-POSS system, we report Density Functional Theory (DFT) results on POSS binding energies to the Pd(110) surface, hydrogen storing ability of POSS, and possible pathways of hydrogen radicals from the catalyst surface to unsaturated bonds away from the surface.

  2. Fuels and energy for the future: The role of catalysis

    SciTech Connect (OSTI)

    Rostrup-Nielsen, J.R.; Nielsen, R.

    2004-07-01

    There are many reasons to decrease the dependency on oil and to increase the use of other energy sources than fossil fuels. The wish for energy security is balanced by a wish for sustainable growth. Catalysis plays an important role in creating new routes and flexibility in the network of energy sources, energy carriers, and energy conversion. The process technologies resemble those applied in the large scale manufacture of commodities. This is illustrated by examples from refinery fuels, synfuels, and hydrogen and the future role of fossil fuels is discussed.

  3. USD Catalysis Group for Alternative Energy - Final report

    SciTech Connect (OSTI)

    Hoefelmeyer, James

    2014-10-03

    I. Project Summary Catalytic processes are a major technological underpinning of modern society, and are essential to the energy sector in the processing of chemical fuels from natural resources, fine chemicals synthesis, and energy conversion. Advances in catalyst technology are enormously valuable since these lead to reduced chemical waste, reduced energy loss, and reduced costs. New energy technologies, which are critical to future economic growth, are also heavily reliant on catalysts, including fuel cells and photo-electrochemical cells. Currently, the state of South Dakota is underdeveloped in terms of research infrastructure related to catalysis. If South Dakota intends to participate in significant economic growth opportunities that result from advances in catalyst technology, then this area of research needs to be made a high priority for investment. To this end, a focused research effort is proposed in which investigators from The University of South Dakota (USD) and The South Dakota School of Mines and Technology (SDSMT) will contribute to form the South Dakota Catalysis Group (SDCG). The multidisciplinary team of the (SDCG) include: (USD) Dan Engebretson, James Hoefelmeyer, Ranjit Koodali, and Grigoriy Sereda; (SDSMT) Phil Scott Ahrenkiel, Hao Fong, Jan Puszynski, Rajesh Shende, and Jacek Swiatkiewicz. The group is well suited to engage in a collaborative project due to the resources available within the existing programs. Activities within the SDCG will be monitored through an external committee consisting of three distinguished professors in chemistry. The committee will provide expert advice and recommendations to the SDCG. Advisory meetings in which committee members interact with South Dakota investigators will be accompanied by individual oral and poster presentations in a materials and catalysis symposium. The symposium will attract prominent scientists, and will enhance the visibility of research in the state of South Dakota. The SDCG requests funding through the Department of Energy (DoE) to establish this multidisciplinary research cluster in the area of catalysis. This long-term approach includes synthesis, characterization, catalyst evaluation, modeling, and scale-up. The project includes plans to acquire instrumentation critical to enabling competitive research. These acquisitions will complement existing resources in the state. The effect of implementation of the proposed efforts will be to significantly enhance state infrastructure in personnel and equipment, and lead to a nationally and internationally recognized research center.

  4. Complex of transferrin with ruthenium for medical applications. [Ru 97, Ru 103

    DOE Patents [OSTI]

    Richards, P.; Srivastava, S.C.; Meinken, G.E.

    1980-11-03

    A novel Ruthenium-transferrin complex, prepared by reacting iron-free human transferrin dissolved in a sodium acetate solution at pH 7 with ruthenium by heating at about 40/sup 0/C for about 2 hours, and purifying said complex by means of gel chromatography with pH 7 sodium acetate as eluent. The mono- or di-metal complex produced can be used in nuclear medicine in the diagnosis and/or treatment of tumors and abscesses. Comparitive results with Ga-67-citrate, which is the most widely used tumor-localizing agent in nuclear medicine, indicate increased sensitivity of detection and greater tumor uptake with the Ru-transferrin complex.

  5. Final technical report, Symposium on New Theoretical Concepts and Directions in Catalysis

    SciTech Connect (OSTI)

    Metiu, Horia

    2014-08-22

    We organized in August 2013 a “Symposium on New Theoretical Concepts and Directions in Catalysis” with the participation of 20 invited distinguished quantum chemists and other researchers who use computations to study catalysis. Symposium website; http://catalysis.cnsi.ucsb.edu/

  6. Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control

    Broader source: Energy.gov (indexed) [DOE]

    | Department of Energy PDF icon 2002_deer_aardahl.pdf More Documents & Publications Heavy-Duty NOx Emissions Control: Reformer-Assisted vs. Plasma-Facilitated Lean NOx Catalysis Selective reduction of NOx in oxygen rich environments with plasma-assisted catalysis: Catalyst development and mechanistic studies

  7. UV resonance Raman analysis of trishomocubane and diamondoid dimers

    SciTech Connect (OSTI)

    Meinke, Reinhard Thomsen, Christian; Maultzsch, Janina; Richter, Robert; Merli, Andrea; Fokin, Andrey A.; Department of Organic Chemistry, Kiev Polytechnic Institute, pr. Pobedy 37, 03056 Kiev ; Koso, Tetyana V.; Schreiner, Peter R.; Rodionov, Vladimir N.

    2014-01-21

    We present resonance Raman measurements of crystalline trishomocubane and diamantane dimers containing a C=C double bond. Raman spectra were recorded with excitation energies between 2.33eV and 5.42eV. The strongest enhancement is observed for the C=C stretch vibration and a bending mode involving the two carbon atoms of the C=C bond, corresponding to the B{sub 2g} wagging mode of ethylene. This is associated with the localization of the ?-HOMO and LUMO and the elongation of the C=C bond length and a pyramidalization of the two sp{sup 2}-hybridized carbon atoms at the optical excitation. The observed Raman resonance energies of the trishomocubane and diamantane dimers are significantly lower than the HOMO-LUMO gaps of the corresponding unmodified diamondoids.

  8. Fundamental Studies in Catalysis Enabled the use of Efficient Lean-Burn Engines for Vehicle Transportation

    Broader source: Energy.gov [DOE]

    Building on a catalysis research program sponsored by EEREs Vehicles Technology Office (VTO) and DOEs Office of Science, researchers at Cummins, Inc. and Pacific Northwest National Laboratory ...

  9. On the photophysics and photochemistry of the water dimer

    SciTech Connect (OSTI)

    Segarra-Marti, Javier; Merchan, Manuela; Roca-Sanjuan, Daniel; Lindh, Roland

    2012-12-28

    The photochemistry of the water dimer irradiated by UV light is studied by means of the complete active space perturbation theory//complete active space self-consistent field (CASPT2//CASSCF) method and accurate computational approaches like as minimum energy paths. Both electronic structure computations and ab initio molecular dynamics simulations are carried out. The results obtained show small shifts relative to a single water molecule on the vertical excitation energies of the dimer due to the hydrogen bond placed between the water donor (W{sub D}) and the water acceptor (W{sub A}). A red-shift and a blue-shift are predicted for the W{sub D} and W{sub A}, respectively, supporting previous theoretical and experimental results. The photoinduced chemistry of the water dimer is described as a process occurring between two single water molecules in which the effect of the hydrogen bond plays a minor role. Thus, the photoinduced decay routes correspond to two photodissociation processes, one for each water molecule. The proposed mechanism for the decay channels of the lowest-lying excited states of the system is established as the photochemical production of a hydrogen-bonded H{sub 2}O Horizontal-Ellipsis HO species plus a hydrogen H atom.

  10. Improving Catalysis by Putting the Best Face Forward | U.S. DOE Office of

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Science (SC) Improving Catalysis by Putting the Best Face Forward Basic Energy Sciences (BES) BES Home About Research Facilities Science Highlights Benefits of BES Funding Opportunities Basic Energy Sciences Advisory Committee (BESAC) Community Resources Contact Information Basic Energy Sciences U.S. Department of Energy SC-22/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3081 F: (301) 903-6594 E: Email Us More Information » 04.01.12 Improving Catalysis by

  11. Catalysis Center for Energy Innovation (CCEI) | U.S. DOE Office of Science

    Office of Science (SC) Website

    (SC) Catalysis Center for Energy Innovation (CCEI) Energy Frontier Research Centers (EFRCs) EFRCs Home Centers EFRC External Websites Research Science Highlights News & Events Publications History Contact BES Home Centers Catalysis Center for Energy Innovation (CCEI) Print Text Size: A A A FeedbackShare Page CCEI Header Director Dionisios Vlachos Lead Institution University of Delaware Year Established 2009 Mission To focus on developing innovative, transformational heterogeneous

  12. Effects of Ar plasma treatment for deposition of ruthenium film by remote plasma atomic layer deposition

    SciTech Connect (OSTI)

    Park, Taeyong; Lee, Jaesang; Park, Jingyu; Jeon, Heeyoung; Jeon, Hyeongtag; Lee, Ki-Hoon; Cho, Byung-Chul; Kim, Moo-Sung; Ahn, Heui-Bok

    2012-01-15

    Ruthenium thin films were deposited on argon plasma-treated SiO{sub 2} and untreated SiO{sub 2} substrates by remote plasma atomic layer deposition using bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp){sub 2}] as a Ru precursor and ammonia plasma as a reactant. The results of in situ Auger electron spectroscopy (AES) analysis indicate that the initial transient region of Ru deposition was decreased by Ar plasma treatment at 400 deg. C, but did not change significantly at 300 deg. C The deposition rate exhibited linearity after continuous film formation and the deposition rates were about 1.7 A/cycle and 0.4 A/cycle at 400 deg. C and 300 deg. C, respectively. Changes of surface energy and polar and dispersive components were measured by the sessile drop test. The quantity of surface amine groups was measured from the surface nitrogen concentration with AES. Furthermore, the Ar plasma-treated SiO{sub 2} contained more amine groups and less hydroxyl groups on the surface than on untreated SiO{sub 2}. Auger spectra exhibited chemical shifts by Ru-O bonding, and larger shifts were observed on untreated substrates due to the strong adhesion of Ru films.

  13. Application of solid ash based catalysts in heterogeneous catalysis

    SciTech Connect (OSTI)

    Shaobin Wang

    2008-10-01

    Solid wastes, fly ash, and bottom ash are generated from coal and biomass combustion. Fly ash is mainly composed of various metal oxides and possesses higher thermal stability. Utilization of fly ash for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. On the one hand, due to the higher stability of its major component, aluminosilicates, fly ash could be employed as catalyst support by impregnation of other active components for various reactions. On the other hand, other chemical compounds in fly ash such as Fe{sub 2}O{sub 3} could also provide an active component making fly ash a catalyst for some reactions. In this paper, physicochemical properties of fly ash and its applications for heterogeneous catalysis as a catalyst support or catalyst in a variety of catalytic reactions were reviewed. Fly-ash-supported catalysts have shown good catalytic activities for H{sub 2} production, deSOx, deNOx, hydrocarbon oxidation, and hydrocracking, which are comparable to commercially used catalysts. As a catalyst itself, fly ash can also be effective for gas-phase oxidation of volatile organic compounds, aqueous-phase oxidation of organics, solid plastic pyrolysis, and solvent-free organic synthesis. 107 refs., 4 figs., 2 tabs.

  14. Unexpected methyl migrations of ethanol dimer under synchrotron VUV radiation

    SciTech Connect (OSTI)

    Xiao, Weizhan; Hu, Yongjun E-mail: lssheng@ustc.edu.cn; Li, Weixing; Guan, Jiwen; Liu, Fuyi; Shan, Xiaobin; Sheng, Liusi E-mail: lssheng@ustc.edu.cn

    2015-01-14

    While methyl transfer is well known to occur in the enzyme- and metal-catalyzed reactions, the methyl transfer in the metal-free organic molecules induced by the photon ionization has been less concerned. Herein, vacuum ultraviolet single photon ionization and dissociation of ethanol dimer are investigated with synchrotron radiation photoionization mass spectroscopy and theoretical methods. Besides the protonated clusters cation (C{sub 2}H{sub 5}OH) ⋅ H{sup +} (m/z = 47) and the β-carbon-carbon bond cleavage fragment CH{sub 2}O ⋅ (C{sub 2}H{sub 5}OH)H{sup +} (m/z = 77), the measured mass spectra revealed that a new fragment (C{sub 2}H{sub 5}OH) ⋅ (CH{sub 3}){sup +} (m/z = 61) appeared at the photon energy of 12.1 and 15.0 eV, where the neutral dimer could be vertically ionized to higher ionic state. Thereafter, the generated carbonium ions are followed by a Wagner-Meerwein rearrangement and then dissociate to produce this new fragment, which is considered to generate after surmounting a few barriers including intra- and inter-molecular methyl migrations by the aid of theoretical calculations. The appearance energy of this new fragment is measured as 11.55 ± 0.05 eV by scanning photoionization efficiency curve. While the signal intensity of fragment m/z = 61 starts to increase, the fragments m/z = 47 and 77 tend to slowly incline around 11.55 eV photon energy. This suggests that the additional fragment channels other than (C{sub 2}H{sub 5}OH) ⋅ H{sup +} and CH{sub 2}O ⋅ (C{sub 2}H{sub 5}OH)H{sup +} have also been opened, which consume some dimer cations. The present report provides a clear description of the photoionization and dissociation processes of the ethanol dimer in the range of the photon energy 12-15 eV.

  15. Photochemical dimerization and functionalization of alkanes, ethers, primary alcohols and silanes

    DOE Patents [OSTI]

    Crabtree, Robert H. (Bethany, CT); Brown, Stephen H. (East Haven, CT)

    1988-01-01

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary alcohols and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  16. Photochemical dimerization and functionalization of alkanes, ethers, primary alcohols and silanes

    DOE Patents [OSTI]

    Crabtree, R.H.; Brown, S.H.

    1988-02-16

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary alcohols and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  17. Structural Insights into the Mechanism of PEPCK Catalysis

    SciTech Connect (OSTI)

    Holyoak,T.; Sullivan, S.; Nowak, T.

    2006-01-01

    Phosphoenolpyruvate carboxykinase catalyzes the reversible decarboxylation of oxaloacetic acid with the concomitant transfer of the {gamma}-phosphate of GTP to form PEP and GDP as the first committed step of gluconeogenesis and glyceroneogenesis. The three structures of the mitochondrial isoform of PEPCK reported are complexed with Mn{sup 2+}, Mn{sup 2+}-PEP, or Mn{sup 2+}-malonate-Mn{sup 2+}GDP and provide the first observations of the structure of the mitochondrial isoform and insight into the mechanism of catalysis mediated by this enzyme. The structures show the involvement of the hyper-reactive cysteine (C307) in the coordination of the active site Mn{sup 2+}. Upon formation of the PEPCK-Mn{sup 2+}-PEP or PEPCK-Mn{sup 2+}-malonate-Mn{sup 2+}GDP complexes, C307 coordination is lost as the P-loop in which it resides adopts a different conformation. The structures suggest that stabilization of the cysteine-coordinated metal geometry holds the enzyme as a catalytically incompetent metal complex and may represent a previously unappreciated mechanism of regulation. A third conformation of the mobile P-loop in the PEPCK-Mn{sup 2+}-malonate-Mn{sup 2+}GDP complex demonstrates the participation of a previously unrecognized, conserved serine residue (S305) in mediating phosphoryl transfer. The ordering of the mobile active site lid in the PEPCK-Mn{sup 2+}-malonate-Mn{sup 2+}GDP complex yields the first observation of this structural feature and provides additional insight into the mechanism of phosphoryl transfer.

  18. Shape-selective catalysis in dimethyl ether conversion

    SciTech Connect (OSTI)

    Sardesai, A.; Lee, S.

    1999-07-01

    Coal-derived syngas can be effectively converted to dimethyl ether (DME) in a single-stage, liquid-phase process. This Liquid Phase Dimethyl Ether (LPDME) process utilizes a dual catalytic system, which comprises of a physical blend between the methanol synthesis and the methanol dehydration catalyst slurried in an inert mineral oil. Such produced DME has vast potential as a building block chemical in the petrochemical industry to produce value-added specialty chemicals. The current research efforts are made to exploit the utilization of shape-selective catalysis using zeolites to produce targeted petrochemicals, including lower olefinic hydrocarbons. The catalysts probed in this investigation include zeolites of different physical, morphological, and chemical configurations. The effect of acidity of ZSM-5 type zeolites as well as the effect of the different channel size and orientation of the zeolites on product selectivity and catalyst deactivation are examined. Results obtained from experimentation of this study show that ZSM-5 type zeolite with low acidity (high SiO{sub 2}/Al{sub 2}O{sub 3} ratio, in this case 150) exhibits the highest selectivity towards lower (C{sub 2}-C{sub 4}) olefins in general. Controlled selectivity toward targeted olefinic species can be accomplished via devising catalytic reaction systems in such a way that the structural property of the catalyst and reactive interaction between molecules in the pores are geared toward formation of targeted molecular species which also at the same time prevent the formation of less desirable products. The internal morphology of the catalyst also has a pronounced effect on the deactivation phenomenon, where it is observed that zeolites possessing high acidity and a unidimensional channel structure are prone towards catalyst deactivation by coking and pore blockage.

  19. Ruthenium ion-catalyzed oxidation of Shenfu coal and its residues

    SciTech Connect (OSTI)

    Yao-Guo Huang; Zhi-Min Zong; Zi-Shuo Yao; Yu-Xuan Zheng; Jie Mou; Guang-Feng Liu; Jin-Pei Cao; Ming-Jie Ding; Ke-Ying Cai; Feng Wang; Wei Zhao; Zhi-Lin Xia; Lin Wu; Xian-Yong Wei

    2008-05-15

    Shenfu coal (SFC), its liquefaction residue (RL), and carbon disulfide (CS{sub 2})/tetrahydrofuran (THF)-inextractable matter (RE) were subject to ruthenium ion-catalyzed oxidation to understand the differences in structural features among the above three samples. The results suggest that SFC is rich in long-chain arylalkanes and {alpha}. {omega}-diarylalkanes (DAAs) with carbon number of methylene linkage from 2 to 4 and that long-chain arylalkanes and DAAs are reactive toward hydroliquefaction and soluble in a CS{sub 2}/THF mixed solvent, whereas highly condensed aromatic species in SFC show poor solubility in the CS{sub 2}/THF mixed solvent. 29 refs., 6 figs., 4 tabs.

  20. Converting Homogeneous to Heterogeneous in Electrophilic Catalysis using Monodisperse Metal Nanoparticles

    SciTech Connect (OSTI)

    Witham, Cole A.; Huang, Wenyu; Tsung, Chia-Kuang; Kuhn, John N.; Somorjai, Gabor A.; Toste, F. Dean

    2009-10-15

    A continuing goal in catalysis is the transformation of processes from homogeneous to heterogeneous. To this end, nanoparticles represent a new frontier in heterogeneous catalysis, where this conversion is supplemented by the ability to obtain new or divergent reactivity and selectivity. We report a novel method for applying heterogeneous catalysts to known homogeneous catalytic reactions through the design and synthesis of electrophilic platinum nanoparticles. These nanoparticles are selectively oxidized by the hypervalent iodine species PhICl{sub 2}, and catalyze a range of {pi}-bond activation reactions previously only homogeneously catalyzed. Multiple experimental methods are utilized to unambiguously verify the heterogeneity of the catalytic process. The discovery of treatments for nanoparticles that induce the desired homogeneous catalytic activity should lead to the further development of reactions previously inaccessible in heterogeneous catalysis. Furthermore, our size and capping agent study revealed that Pt PAMAM dendrimer-capped nanoparticles demonstrate superior activity and recyclability compared to larger, polymer-capped analogues.

  1. 2010 CATALYSIS GORDON RESEARCH CONFERENCE, JUNE 27 - JULY 2, 2010, NEW LONDON, NEW HAMPSHIRE

    SciTech Connect (OSTI)

    Abhaya Datye

    2010-07-02

    Catalysis is a key technology for improving the quality of life while simultaneously reducing the adverse impact of human activities on the environment. The discovery of new catalytic processes and the improvement of existing ones are also critically important for securing the nation's energy supply. The GRC on Catalysis is considered one the most prestigious conference for catalysis research, bringing together leading researchers from both academia, industry and national labs to discuss the latest, most exciting research in catalysis and the future directions for the field. The 2010 GRC on Catalysis will follow time-honored traditions and feature invited talks from the world's leading experts in the fundamentals and applications of catalytic science and technology. We plan to have increased participation from industry. The extended discussions in the company of outstanding thinkers will stimulate and foster new science. The conference will include talks in the following areas: Alternative feedstocks for chemicals and fuels, Imaging and spectroscopy, Design of novel catalysts, Catalyst preparation fundamentals, Molecular insights through theory, Surface Science, Catalyst stability and dynamics. In 2010, the Catalysis conference will move to a larger conference room with a new poster session area that will allow 40 posters per session. The dorm rooms provide single and double accommodations, free WiFi and the registration fee includes all meals and the famous lobster dinner on Thursday night. Afternoons are open to enjoy the New England ambiance with opportunities for hiking, sailing, golf and tennis to create an outstanding conference that will help you network with colleagues, and make long lasting connections.

  2. Geek-Up[3.11.2011]: Energy Efficiency, Catalysis and Open Source Tools |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy 11.2011]: Energy Efficiency, Catalysis and Open Source Tools Geek-Up[3.11.2011]: Energy Efficiency, Catalysis and Open Source Tools March 11, 2011 - 4:37pm Addthis L. Keith Woo | Photo courtesy of Ames National Laboratory L. Keith Woo | Photo courtesy of Ames National Laboratory Niketa Kumar Niketa Kumar Public Affairs Specialist, Office of Public Affairs Ames Laboratory researcher and Iowa State University professor L. Keith Woo is on the search for catalysts that lead

  3. Growth mechanism of graphene on platinum: Surface catalysis and carbon segregation

    SciTech Connect (OSTI)

    Sun, Jie Lindvall, Niclas; Yurgens, August; Nam, Youngwoo; Cole, Matthew T.; Teo, Kenneth B. K.; Woo Park, Yung

    2014-04-14

    A model of the graphene growth mechanism of chemical vapor deposition on platinum is proposed and verified by experiments. Surface catalysis and carbon segregation occur, respectively, at high and low temperatures in the process, representing the so-called balance and segregation regimes. Catalysis leads to self-limiting formation of large area monolayer graphene, whereas segregation results in multilayers, which evidently grow from below. By controlling kinetic factors, dominantly monolayer graphene whose high quality has been confirmed by quantum Hall measurement can be deposited on platinum with hydrogen-rich environment, quench cooling, tiny but continuous methane flow and about 1000?C growth temperature.

  4. Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications

    SciTech Connect (OSTI)

    Parks, II, James E; Storey, John Morse; Theiss, Timothy J; Ponnusamy, Senthil; Ferguson, Harley Douglas; Williams, Aaron M; Tassitano, James B

    2007-09-01

    Distributed energy is an approach for meeting energy needs that has several advantages. Distributed energy improves energy security during natural disasters or terrorist actions, improves transmission grid reliability by reducing grid load, and enhances power quality through voltage support and reactive power. In addition, distributed energy can be efficient since transmission losses are minimized. One prime mover for distributed energy is the natural gas reciprocating engine generator set. Natural gas reciprocating engines are flexible and scalable solutions for many distributed energy needs. The engines can be run continuously or occasionally as peak demand requires, and their operation and maintenance is straightforward. Furthermore, system efficiencies can be maximized when natural gas reciprocating engines are combined with thermal energy recovery for cooling, heating, and power applications. Expansion of natural gas reciprocating engines for distributed energy is dependent on several factors, but two prominent factors are efficiency and emissions. Efficiencies must be high enough to enable low operating costs, and emissions must be low enough to permit significant operation hours, especially in non-attainment areas where emissions are stringently regulated. To address these issues the U.S. Department of Energy and the California Energy Commission launched research and development programs called Advanced Reciprocating Engine Systems (ARES) and Advanced Reciprocating Internal Combustion Engines (ARICE), respectively. Fuel efficiency and low emissions are two primary goals of these programs. The work presented here was funded by the ARES program and, thus, addresses the ARES 2010 goals of 50% thermal efficiency (fuel efficiency) and <0.1 g/bhp-hr emissions of oxides of nitrogen (NOx). A summary of the goals for the ARES program is given in Table 1-1. ARICE 2007 goals are 45% thermal efficiency and <0.015 g/bhp-hr NOx. Several approaches for improving the efficiency and emissions of natural gas reciprocating engines are being pursued. Approaches include: stoichiometric engine operation with exhaust gas recirculation and three-way catalysis, advanced combustion modes such as homogeneous charge compression ignition, and extension of the lean combustion limit with advanced ignition concepts and/or hydrogen mixing. The research presented here addresses the technical approach of combining efficient lean spark-ignited natural gas combustion with low emissions obtained from a lean NOx trap catalyst aftertreatment system. This approach can be applied to current lean engine technology or advanced lean engines that may result from related efforts in lean limit extension. Furthermore, the lean NOx trap technology has synergy with hydrogen-assisted lean limit extension since hydrogen is produced from natural gas during the lean NOx trap catalyst system process. The approach is also applicable to other lean engines such as diesel engines, natural gas turbines, and lean gasoline engines; other research activities have focused on those applications. Some commercialization of the technology has occurred for automotive applications (both diesel and lean gasoline engine vehicles) and natural gas turbines for stationary power. The research here specifically addresses barriers to commercialization of the technology for large lean natural gas reciprocating engines for stationary power. The report presented here is a comprehensive collection of research conducted by Oak Ridge National Laboratory (ORNL) on lean NOx trap catalysis for lean natural gas reciprocating engines. The research was performed in the Department of Energy's ARES program from 2003 to 2007 and covers several aspects of the technology. All studies were conducted at ORNL on a Cummins C8.3G+ natural gas engine chosen based on industry input to simulate large lean natural gas engines. Specific technical areas addressed by the research include: NOx reduction efficiency, partial oxidation and reforming chemistry, and the effects of sulfur poisons on the partial oxidation, reformer, and lean NOx trap catalysts. The initial work on NOx reduction efficiency demonstrated that NOx emissions <0.1 g/bhp-hr (the ARES goal) can be achieved with the lean NOx trap catalyst technology. Subsequent work focused on cost and size optimization and durability issues which addressed two specific ARES areas of interest to industry ('Cost of Power' and 'Availability, Reliability, and Maintainability', respectively). Thus, the research addressed the approach of the lean NOx trap catalyst technology toward the ARES goals as shown in Table 1-1.

  5. Nonlocal fluctuations and control of dimer entanglement dynamics

    SciTech Connect (OSTI)

    Susa, Cristian E.; Reina, John H.

    2010-10-15

    We report on the dissipative dynamics of an entangled, bipartite interacting system. We show how to induce and control the so-called early-stage disentanglement (and 'delayed' entanglement generation) dynamics by means of a driving laser field. We demonstrate that some of the features currently associated with pure non-Markovian effects in such entanglement behavior can actually take place in Markovian environments if background-noise quantum electrodynamics fluctuations are considered. We illustrate this for the case of a dimer interacting molecular system for which emission rates, interaction strength, and radiative corrections have been previously measured. We also show that even in the absence of collective decay mechanisms and qubit-qubit interactions, the entanglement still exhibits collapse-revival behavior. Our results indicate that zero-point energy fluctuations should be taken into account when formulating precise entanglement dynamics statements.

  6. ISHHC XIII International Symposium on the Relations betweenHomogeneous and Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Somorjai , G.A.

    2007-06-11

    The International Symposium on Relations between Homogeneous and Heterogeneous Catalysis (ISHHC) has a long and distinguished history. Since 1974, in Brussels, this event has been held in Lyon, France (1977), Groeningen, The Netherlands (1981); Asilomar, California (1983); Novosibirsk, Russia (1986); Pisa, Italy (1989); Tokyo, Japan (1992); Balatonfuered, Hungary (1995); Southampton, United Kingdom (1999); Lyon, France (2001); Evanston, Illinois (2001) and Florence, Italy (2005). The aim of this international conference in Berkeley is to bring together practitioners in the three fields of catalysis, heterogeneous, homogeneous and enzyme, which utilize mostly nanosize particles. Recent advances in instrumentation, synthesis and reaction studies permit the nanoscale characterization of the catalyst systems, often for the same reaction, under similar experimental conditions. It is hoped that this circumstance will permit the development of correlations of these three different fields of catalysis on the molecular level. To further this goal we aim to uncover and focus on common concepts that emerge from nanoscale studies of structures and dynamics of the three types of catalysts. Another area of focus that will be addressed is the impact on and correlation of nanosciences with catalysis. There is information on the electronic and atomic structures of nanoparticles and their dynamics that should have importance in catalyst design and catalytic activity and selectivity.

  7. Photochemical dimerization and functionalization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and silanes

    DOE Patents [OSTI]

    Crabtree, Robert H. (Bethany, CT); Brown, Stephen H. (East Haven, CT)

    1989-01-01

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and primary, secondary and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  8. Photochemical dimerization and functionalization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and silanes

    DOE Patents [OSTI]

    Crabtree, R.H.; Brown, S.H.

    1989-10-17

    The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and primary, secondary and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

  9. Rhodium mediated bond activation: from synthesis to catalysis

    SciTech Connect (OSTI)

    Ho, Hung-An

    2012-03-06

    Recently, our lab has developed monoanionic tridentate ligand, To{sup R}, showing the corresponding coordination chemistry and catalyst reactivity of magnesium, zirconium, zinc and iridium complexes. This thesis details synthetic chemistry, structural study and catalytic reactivity of the To{sup R}-supported rhodium compounds. Tl[To{sup R}] has been proved to be a superior ligand transfer agent for synthesizing rhodium complexes. The salt metathesis route of Tl[To{sup M}] with [Rh({mu}-Cl)(CO)]{sub 2} and [Rh({mu}- Cl)(COE)]{sub 2} gives To{sup M}Rh(CO){sub 2} (2.2) and To{sup M}RhH({eta}{sup 3}-C{sub 8}H{sub 13}) (3.1) respectively while Tl[To{sup P}] with [Rh({mu}-Cl)(CO)]{sub 2} affords To{sup P}Rh(CO){sub 2} (2.3). 2.2 reacts with both strong and weak electrophiles, resulting in the oxazoline N-attacked and the metal center-attacked compounds correspondingly. Using one of the metal center-attacked electrophiles, 2.3 was demonstrated to give high diastereoselectivity. Parallel to COE allylic C-H activation complex 3.1, the propene and allylbenzene allylic C-H activation products have also been synthesized. The subsequent functionalization attempts have been examined by treating with Brnsted acids, Lewis acids, electrophiles, nucleophiles, 1,3-dipolar reagents and reagents containing multiple bonds able to be inserted. Various related complexes have been obtained under these conditions, in which one of the azide insertion compounds reductively eliminates to give an allylic functionalization product stoichiometrically. 3.1 reacts with various primary alcohols to give the decarbonylation dihydride complex To{sup M}Rh(H){sub 2}CO (4.1). 4.1 shows catalytic reactivity for primary alcohol decarbonylation under a photolytic condition. Meanwhile, 2.2 has been found to be more reactive than 4.1 for catalytic alcohol decarbonylation under the same condition. Various complexes and primary alcohols have been investigated as well. The proposed mechanism is based on the stochiometric reactions of the possible metal and organic intermediates. Primary amines, hypothesized to undergo a similar reaction pathway, have been verified to give dehydrogenative coupling product, imines. In the end, the well-developed neutral tridentate Tpm coordinates to the rhodium bis(ethylene) dimer in the presence of TlPF{sub 6} to give the cationic complex, [TpmRh(C{sub 2}H{sub 4}){sub 2}][PF{sub 6}] (5.1). 5.1 serves as the first example of explicit determination of the solid state hapticity, evidenced by X-ray structure, among all the cationic Tpm{sup R}M(C{sub 2}H{sub 4}){sub 2}{sup +} (Tpm{sup R} = Tpm, Tpm*, M = Rh, Ir) derivatives. The substitution chemistry of this compound has been studied by treating with soft and hard donors. The trimethylphosphine-sbustituted complex activates molecular hydrogen to give the dihydride compound.

  10. Hydrous ruthenium oxide nanoparticles anchored to graphene and carbon nanotube hybrid foam for supercapacitors

    SciTech Connect (OSTI)

    Wang, Wei; Guo, S.; Lee, I.; Ahmed, K.; Zhong, J.; Favors, Z.; Zaera, F.; Ozkan, M.; Ozkan, C. S

    2014-03-25

    In real life applications, supercapacitors (SCs) often can only be used as part of a hybrid system together with other high energy storage devices due to their relatively lower energy density in comparison to other types of energy storage devices such as batteries and fuel cells. Increasing the energy density of SCs will have a huge impact on the development of future energy storage devices by broadening the area of application for SCs. Here, we report a simple and scalable way of preparing a three-dimensional (3D) sub-5 nm hydrous ruthenium oxide (RuO?) anchored graphene and CNT hybrid foam (RGM) architecture for high-performance supercapacitor electrodes. This RGM architecture demonstrates a novel graphene foam conformally covered with hybrid networks of RuO? nanoparticles and anchored CNTs. SCs based on RGM show superior gravimetric and per-area capacitive performance (specific capacitance: 502.78 F g?, areal capacitance: 1.11 F cm?) which leads to an exceptionally high energy density of 39.28 Wh kg? and power density of 128.01 kW kg?. The electrochemical stability, excellent capacitive performance, and the ease of preparation suggest this RGM system is promising for future energy storage applications.

  11. Photoexcited energy transfer in a weakly coupled dimer

    SciTech Connect (OSTI)

    Hernandez, Laura Alfonso; Nelson, Tammie; Tretiak, Sergei; Fernandez-Alberti, Sebastian

    2015-01-08

    Nonadiabatic excited-state molecular dynamics (NA-ESMD) simulations have been performed in order to study the time-dependent exciton localization during energy transfer between two chromophore units of the weakly coupled anthracene dimer dithia-anthracenophane (DTA). Simulations are done at both low temperature (10 K) and room temperature (300 K). The initial photoexcitation creates an exciton which is primarily localized on a single monomer unit. Subsequently, the exciton experiences an ultrafast energy transfer becoming localized on either one monomer unit or the other, whereas delocalization between both monomers never occurs. In half of the trajectories, the electronic transition density becomes completely localized on the same monomer as the initial excitation, while in the other half, it becomes completely localized on the opposite monomer. In this article, we present an analysis of the energy transfer dynamics and the effect of thermally induced geometry distortions on the exciton localization. Finally, simulated fluorescence anisotropy decay curves for both DTA and the monomer unit dimethyl anthracene (DMA) are compared. As a result, our analysis reveals that changes in the transition density localization caused by energy transfer between two monomers in DTA is not the only source of depolarization and exciton relaxation within a single DTA monomer unit can also cause reorientation of the transition dipole.

  12. Photoexcited energy transfer in a weakly coupled dimer

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hernandez, Laura Alfonso; Nelson, Tammie; Tretiak, Sergei; Fernandez-Alberti, Sebastian

    2015-01-08

    Nonadiabatic excited-state molecular dynamics (NA-ESMD) simulations have been performed in order to study the time-dependent exciton localization during energy transfer between two chromophore units of the weakly coupled anthracene dimer dithia-anthracenophane (DTA). Simulations are done at both low temperature (10 K) and room temperature (300 K). The initial photoexcitation creates an exciton which is primarily localized on a single monomer unit. Subsequently, the exciton experiences an ultrafast energy transfer becoming localized on either one monomer unit or the other, whereas delocalization between both monomers never occurs. In half of the trajectories, the electronic transition density becomes completely localized on themore » same monomer as the initial excitation, while in the other half, it becomes completely localized on the opposite monomer. In this article, we present an analysis of the energy transfer dynamics and the effect of thermally induced geometry distortions on the exciton localization. Finally, simulated fluorescence anisotropy decay curves for both DTA and the monomer unit dimethyl anthracene (DMA) are compared. As a result, our analysis reveals that changes in the transition density localization caused by energy transfer between two monomers in DTA is not the only source of depolarization and exciton relaxation within a single DTA monomer unit can also cause reorientation of the transition dipole.« less

  13. MERCURY-NITRITE-RHODIUM-RUTHENIUM INTERACTIONS IN NOBLE METAL CATALYZED HYDROGEN GENERATION FROM FORMIC ACID DURING NUCLEAR WASTE PROCESSING AT THE SAVANNAH RIVER SITE - 136C

    SciTech Connect (OSTI)

    Koopman, D.; Pickenheim, B.; Lambert, D.; Newell, J; Stone, M.

    2009-09-02

    Chemical pre-treatment of radioactive waste at the Savannah River Site is performed to prepare the waste for vitrification into a stable waste glass form. During pre-treatment, compounds in the waste become catalytically active. Mercury, rhodium, and palladium become active for nitrite destruction by formic acid, while rhodium and ruthenium become active for catalytic conversion of formic acid into hydrogen and carbon dioxide. Nitrite ion is present during the maximum activity of rhodium, but is consumed prior to the activation of ruthenium. Catalytic hydrogen generation during pre-treatment can exceed radiolytic hydrogen generation by several orders of magnitude. Palladium and mercury impact the maximum catalytic hydrogen generation rates of rhodium and ruthenium by altering the kinetics of nitrite ion decomposition. New data are presented that illustrate the interactions of these various species.

  14. Coiled-coil dimerization of the LOV2 domain of the blue-light...

    Office of Scientific and Technical Information (OSTI)

    blue-light photoreceptor phototropin 1 from Arabidopsis thaliana Citation Details In-Document Search Title: Coiled-coil dimerization of the LOV2 domain of the blue-light ...

  15. Evidence for Phenylalanine Zipper-Mediated Dimerization in the X-ray

    Office of Scientific and Technical Information (OSTI)

    Crystal Structure of a Magainin 2 Analogue (Journal Article) | SciTech Connect Evidence for Phenylalanine Zipper-Mediated Dimerization in the X-ray Crystal Structure of a Magainin 2 Analogue Citation Details In-Document Search Title: Evidence for Phenylalanine Zipper-Mediated Dimerization in the X-ray Crystal Structure of a Magainin 2 Analogue Authors: Hayouka, Zvi ; Mortenson, David E. ; Kreitler, Dale F. ; Weisblum, Bernard ; Forest, Katrina T. ; Gellman, Samuel H. [1] + Show Author

  16. Structural bases of dimerization of yeast telomere protein Cdc13 and its

    Office of Scientific and Technical Information (OSTI)

    interaction with the catalytic subunit of DNA polymerase [alpha] (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Structural bases of dimerization of yeast telomere protein Cdc13 and its interaction with the catalytic subunit of DNA polymerase [alpha] Citation Details In-Document Search Title: Structural bases of dimerization of yeast telomere protein Cdc13 and its interaction with the catalytic subunit of DNA polymerase [alpha] Budding yeast

  17. Structure of the N-terminal dimerization domain of CEACAM7 (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect SciTech Connect Search Results Journal Article: Structure of the N-terminal dimerization domain of CEACAM7 Citation Details In-Document Search Title: Structure of the N-terminal dimerization domain of CEACAM7 Authors: Bonsor, Daniel A. ; Beckett, Dorothy ; Sundberg, Eric J. [1] ; Maryland) [2] + Show Author Affiliations (Maryland-MED) ( Publication Date: 2015-10-02 OSTI Identifier: 1214040 Resource Type: Journal Article Resource Relation: Journal Name: Acta

  18. Fuel Synthesis Catalysis Laboratory: Catalytic Testing for Thermochemical Transformations of Molecules (Fact Sheet), NREL (National Renewable Energy Laboratory)

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Synthesis Catalysis Laboratory Catalytic testing for thermochemical transformations of molecules NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. NREL's Fuel Synthesis Catalysis Laboratory (FSCL) provides a wide range of capabilities in heterogeneous catalyst testing. Current research areas of emphasis include the transformation of biomass pyrolysis and gasification products to

  19. Ras-GTP dimers activate the mitogen-activated protein kinase (MAPK) pathway

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Nan, Xiaolin; Tamgüney, Tanja M.; Collisson, Eric A.; Lin, Li -Jung; Pitt, Cameron; Galeas, Jacqueline; Lewis, Sophia; Gray, Joe W.; McCormick, Frank; Chu, Steven

    2015-06-16

    Rat sarcoma (Ras) GTPases regulate cell proliferation and survival through effector pathways including Raf-MAPK, and are the most frequently mutated genes in human cancer. Although it is well established that Ras activity requires binding to both GTP and the membrane, details of how Ras operates on the cell membrane to activate its effectors remain elusive. Efforts to target mutant Ras in human cancers to therapeutic benefit have also been largely unsuccessful. Here we show that Ras-GTP forms dimers to activate MAPK. We used quantitative photoactivated localization microscopy (PALM) to analyze the nanoscale spatial organization of PAmCherry1-tagged KRas 4B (hereafter referredmore » to KRas) on the cell membrane under various signaling conditions. We found that at endogenous expression levels KRas forms dimers, and KRasG12D, a mutant that constitutively binds GTP, activates MAPK. Overexpression of KRas leads to formation of higher order Ras nanoclusters. Conversely, at lower expression levels, KRasG12D is monomeric and activates MAPK only when artificially dimerized. Moreover, dimerization and signaling of KRas are both dependent on an intact CAAX (C, cysteine; A, aliphatic; X, any amino acid) motif that is also known to mediate membrane localization. These results reveal a new, dimerization-dependent signaling mechanism of Ras, and suggest Ras dimers as a potential therapeutic target in mutant Ras-driven tumors.« less

  20. Ras-GTP dimers activate the mitogen-activated protein kinase (MAPK) pathway

    SciTech Connect (OSTI)

    Nan, Xiaolin; Tamgney, Tanja M.; Collisson, Eric A.; Lin, Li -Jung; Pitt, Cameron; Galeas, Jacqueline; Lewis, Sophia; Gray, Joe W.; McCormick, Frank; Chu, Steven

    2015-06-16

    Rat sarcoma (Ras) GTPases regulate cell proliferation and survival through effector pathways including Raf-MAPK, and are the most frequently mutated genes in human cancer. Although it is well established that Ras activity requires binding to both GTP and the membrane, details of how Ras operates on the cell membrane to activate its effectors remain elusive. Efforts to target mutant Ras in human cancers to therapeutic benefit have also been largely unsuccessful. Here we show that Ras-GTP forms dimers to activate MAPK. We used quantitative photoactivated localization microscopy (PALM) to analyze the nanoscale spatial organization of PAmCherry1-tagged KRas 4B (hereafter referred to KRas) on the cell membrane under various signaling conditions. We found that at endogenous expression levels KRas forms dimers, and KRasG12D, a mutant that constitutively binds GTP, activates MAPK. Overexpression of KRas leads to formation of higher order Ras nanoclusters. Conversely, at lower expression levels, KRasG12D is monomeric and activates MAPK only when artificially dimerized. Moreover, dimerization and signaling of KRas are both dependent on an intact CAAX (C, cysteine; A, aliphatic; X, any amino acid) motif that is also known to mediate membrane localization. These results reveal a new, dimerization-dependent signaling mechanism of Ras, and suggest Ras dimers as a potential therapeutic target in mutant Ras-driven tumors.

  1. This research was supported as part of the Catalysis Center for Energy Innovatio

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    This research was supported as part of the Catalysis Center for Energy Innovation, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Improving Efficiencies in Fuel, Chemical and Pharmaceutical Industries Repetitive branching, a novel and simple synthesis method, produces zeolite crystals with large-pore "highways" that improve transport and utilization of chemicals within the crystal This research was

  2. Theoretical/Computational Tools for Energy-Relevant Catalysis | The Ames

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Laboratory Theoretical/Computational Tools for Energy-Relevant Catalysis FWP/Project Description: Project Leader(s): James Evans, Mark Gordon Principal Investigators: James Evans, Mark Gordon This project will develop new strategies for and integrated combinations of electronic structure analysis and statistical mechanical, coarse-grained, and multi-scale modeling approaches to treat energy-relevant heterogeneous catalytic systems. Currently, there is a lack of effective molecular-level

  3. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support of HCCI

    Broader source: Energy.gov (indexed) [DOE]

    Emission Control | Department of Energy Presentation given at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 August, 2007, Detroit, Michigan. Sponsored by the U.S. Department of Energy's (DOE) Office of FreedomCAR and Vehicle Technologies (OFCVT). PDF icon deer07_rappe.pdf More Documents & Publications Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support of HCCI Emission Control Selectlive Catalytic Reducution of NOx wilth Diesel-Based

  4. Kokes Awards for the 22nd North American Catalysis Society Meeting, June 5-10, 2011

    SciTech Connect (OSTI)

    Fabio H. Ribeiro

    2011-06-05

    The biennial North American Catalysis Society (NACS) Meetings are the premiere conferences in the area of catalysis, surface science, and reaction engineering. The 22nd meeting will be held the week of June 5-10, 2011 in Detroit, Michigan. The objective of the Meetings is to bring together leading researchers for intensive scientific exchange and interactions. Financial support that offsets some of the associated costs (specifically, registration fee, airline tickets, and hotel accommodations) would encourage graduate students, and for the first time undergraduate students, to attend and participate meaningfully in this conference. The funds sought in this proposal will help support the Richard J. Kokes Travel Award program. Graduate students eligible for these merit-based Awards are those who study at a North American university and who will present at the Meeting. We have currently 209 applications and we expect to be able to fund about half of them. The NACS has traditionally sought to encourage graduate student, and this year for the first time undergraduate studies, participation at the National Meetings and providing financial support is the most effective means to do so. Their attendance would contribute significantly to their scientific training and communication and presentation skills. They would be exposed to the leading researchers from the US and abroad; they would meet their peers from other universities; they would learn about cutting-edge results that could benefit their research projects; and they may become interested in becoming active participants in the catalysis community. These young investigators represent the next generation of scientists and engineers, and their proper training will lead to future scientific breakthroughs and technological innovations that benefit the US economy. Advances in catalysis can come in the form of more energy-efficient and environmentally-friendly chemical processes, improved fuel cell performance, efficient hydrogen production, and a cleaner environment.

  5. Kokes Awards for the 23rd North American Catalysis Society Meeting

    SciTech Connect (OSTI)

    Jacobs, Gary

    2014-01-31

    The Tri-State Catalysis Society awarded 107 Kokes Travel Awards. The program was very successful and to date this was the most Kokes Travel Awards ever awarded at a North American Catalysis Society Meeting. It provided students who merited an award the opportunity to attend the meeting, present a paper in the form of either an oral presentation or a poster presentation, and to serve the North American Catalysis Society by participating in the organization of the meeting. Students worked very hard during the week of the meeting to make it a success. Financial support for the Kokes awards was provided by DOE, NSF, NACS, as well as the Tri-State Catalysis Society, the latter through fund raising activities, and other donations. AT the meeting, each student received over $1050 in kind to offset the costs of registration fees ($260), hotel accommodations ($295.7), transportation ($400 travel allowance), as well as T-shirts ($20), and banquet tickets ($95 provided by donations from society members). In addition, for the first time, students received certificates that were signed by the President of NACS, Professor Enrique Iglesia, and by the Kokes Awards Chair, Gary Jacobs (see last page). A list of meeting co-chairs (i.e., Uschi M. Graham, Umit S. Ozkan, and Madan Bhassin) and the honorary chair (Burtron H. Davis) was also included on the certificate, along with the name of the recipient. The awardees were chosen on a merit-based guideline which also included the requirements of having a presentation accepted at the meeting and being a student at a North American University. The Richard J. Kokes Student Travel Award Committee (Gary Jacobs, Rodney Andrews, and Peter Smirniotis) with help from the Organizing Committee were able to secure money from four sources as detailed in Table 1. As detailed by our Treasurer, Dr. Helge Toufar of Clariant, the total amount spent was $105,000.

  6. Catalysis by Design: Bridging the Gap Between Theory and Experiments at

    Broader source: Energy.gov (indexed) [DOE]

    Nanoscale Level | Department of Energy Studies on a simple platinum-alumina system constitute a first step toward a "catalyst by design" approach. PDF icon deer08_narula.pdf More Documents & Publications Catalysis by Design: Bridging the Gap between Theory and Experiments Catalyst by Design - Theoretical, Nanostructural, and Experimental Studies of Oxidation Catalyst for Diesel Engine Emission Treatment

  7. NMR Computational Studies of Solid Acidity/Fundamental Studies of Catalysis by Solid Acids

    SciTech Connect (OSTI)

    James F. Haw

    2008-06-28

    This project focused on catalysis by zeolites and the synergy of spectroscopic characterization and theoretical modeling. In collaboration with the Waroquier group in Belgium we used state-of-the-art quantum chemical simulations on a supramolecular model of both the HZSM-5 zeolite and the co-catalytic hydrocarbon pool species and calculated a full catalytic cycle (including all rate constants) for methanol-to-olefin (MTO) catalysis involving a hydrocarbon pool species. This work not only represents the most robust computational analysis of a successful MTO route to date, but it also succeeds in tying together the many experimental clues. That work was featured on the cover of Angewandte Chemie. More recently we elucidated several unsuspected roles for formaldehyde in methanol to olefin catalysis. Formaldehyde proves to be a key species responsible for both the growth of the catalytically active hydrocarbon pool and its inevitable aging into deactivated polycyclic aromatic species. The apparent inevitability of formaldehyde formation at high temperatures, in particular in contact with active metal or metal oxide surfaces, may put some fundamental limitations on the economic potential of conversion of methanol to olefins.

  8. Efficient surface plasmon amplification in gain-assisted silver nanotubes and associated dimers

    SciTech Connect (OSTI)

    Yu, HaiQun; Jiang, ShuMin; Wu, DaJian

    2015-04-21

    SPASER (surface plasmon amplification by stimulated emission of radiation) properties in active SiO{sub 2}Ag nanotubes and associated dimers have been investigated by using the scattering theory and the finite element method. In the active Ag nanotube, as the gain coefficient of the core increases to a critical value, a super-resonance occurs. The SPASER phenomenon also can be found in the active Ag nanotube dimer. The strong couplings between two nanotubes lead to larger gain threshold for the active Ag nanotube dimer compared with the active Ag nanotube. At the super-resonance, the maximal surface enhanced Raman scattering factor at the hot spot in the active Ag nanotube dimer can achieve about 8??10{sup 18}, which is large enough for single molecule detection. Furthermore, with increasing the separation between two Ag nanotubes, the gain threshold value for the super-resonance of the active Ag nanotube dimer decreases, while the corresponding super-resonance wavelength increases first and then decreases.

  9. Dimerization Induced Deprotonation of Water on RuO2(110)

    SciTech Connect (OSTI)

    Mu, Rentao; Cantu Cantu, David; Lin, Xiao; Glezakou, Vassiliki Alexandra; Wang, Zhitao; Lyubinetsky, Igor; Rousseau, Roger J.; Dohnalek, Zdenek

    2014-10-02

    RuO2 has proven to be indispensable as a co-catalyst in numerous systems designed for photocatalytic water splitting. In this study we have carried out a detailed mechanistic study of water behavior on the most stable RuO2 face, RuO2(110), by employing variable temperature scanning tunneling microscopy and density functional theory calculations. We show that water monomers adsorb molecularly on Ru sites, become mobile above 238 K, diffuse along the Ru rows and form water dimers. The onset for dimer diffusion is observed at ~277 K indicating significantly higher diffusion barrier than that for monomers. More importantly, we find that water dimers deprotonate readily to form Ru-bound H3O2 and bridging OH species. The observed behavior is compared and contrasted with that observed for water on isostructural rutile TiO2(110).

  10. A Fundamental Study on the [(μ-Cl)3Mg2(THF)6]+ Dimer Electrolytes for

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Rechargeable Mg Batteries - Joint Center for Energy Storage Research 5, 2015, Research Highlights A Fundamental Study on the [(μ-Cl)3Mg2(THF)6]+ Dimer Electrolytes for Rechargeable Mg Batteries (a) Proposed formation of the Mg-dimer and its equilibrium with Mg-monomers (b) The M/Z isotopic distribution of the [MgCl(THF)3]+ peak in the positive mode of SPIN MS of [(µ-Cl)3Mg2(THF)6]AlPh3Cl. Inset gives the calculated isotopic pattern (c) 25Mg NMR spectra of [(µ-Cl)3Mg2(THF)6]AlPh3Cl in the

  11. Resonant dimer relaxation in cold atoms with a large scattering length

    SciTech Connect (OSTI)

    Braaten, Eric; Hammer, H.-W.

    2007-05-15

    Efimov physics refers to universal phenomena associated with a discrete scaling symmetry in the three-body problem with a large scattering length. The first experimental evidence for Efimov physics was the recent observation of a resonant peak in the three-body recombination rate for {sup 133}Cs atoms with large negative scattering length. There can also be resonant peaks in the atom-dimer relaxation rate for large positive scattering length. We calculate the atom-dimer relaxation rate as a function of temperature and show how measurements of the relaxation rate can be used to determine accurately the parameters that govern Efimov physics.

  12. Electric-field enhanced performance in catalysis and solid-state devices involving gases

    DOE Patents [OSTI]

    Blackburn, Bryan M.; Wachsman, Eric D.; Van Assche, IV, Frederick Martin

    2015-05-19

    Electrode configurations for electric-field enhanced performance in catalysis and solid-state devices involving gases are provided. According to an embodiment, electric-field electrodes can be incorporated in devices such as gas sensors and fuel cells to shape an electric field provided with respect to sensing electrodes for the gas sensors and surfaces of the fuel cells. The shaped electric fields can alter surface dynamics, system thermodynamics, reaction kinetics, and adsorption/desorption processes. In one embodiment, ring-shaped electric-field electrodes can be provided around sensing electrodes of a planar gas sensor.

  13. Morphological variations as nonstandard test parameters for the response to pollutant gas concentration: An application to Ruthenium Phthalocyanine sensing films

    SciTech Connect (OSTI)

    Generosi, A.; Paci, B.; Albertini, V. Rossi; Perfetti, P.; Paoletti, A.M.; Pennesi, G.; Rossi, G.; Caminiti, R.

    2006-03-06

    A systematic time-resolved energy dispersive x-ray reflectometry study was performed in situ on Ruthenium Phthalocyanine thin fims to estimate the morphological detection limits of this material as NO{sub 2} transducer and the influence of the gas concentration on the gas-film interaction mechanisms. The work validates the use of this unconventional method--based on the observation of the morphological parameters change--for evaluating the response of novel sensing materials in alternative to more standard procedures. Indeed, the morphological monitoring is shown to be sensitive to the gas concentration in a range comparable to the usual electroresistive measurements. Moreover, while the latter is only able to give the information on whether the gas is interacting with the sensor, the former is also able to discriminate among interaction processes of a different nature (in the present case the interaction limited to the film surface and the one involving the material bulk)

  14. Understanding catalysis in a multiphasic two-dimensional transition metal dichalcogenide.

    SciTech Connect (OSTI)

    Chou, Stanley Shihyao; Sai, Na; Lu, Ping; Coker, Eric Nicholas; Liu, Sheng; Artyushkova, Kateryna; Luk, Ting S.; Kaehr, Bryan James; Brinker, C. Jeffrey

    2015-10-07

    Establishing processing–structure–property relationships for monolayer materials is crucial for a range of applications spanning optics, catalysis, electronics and energy. Presently, for molybdenum disulfide, a promising catalyst for artificial photosynthesis, considerable debate surrounds the structure/property relationships of its various allotropes. Here we unambiguously solve the structure of molybdenum disulfide monolayers using high-resolution transmission electron microscopy supported by density functional theory and show lithium intercalation to direct a preferential transformation of the basal plane from 2H (trigonal prismatic) to 1T' (clustered Mo). These changes alter the energetics of molybdenum disulfide interactions with hydrogen (ΔGH), and, with respect to catalysis, the 1T' transformation renders the normally inert basal plane amenable towards hydrogen adsorption and hydrogen evolution. Furthermore, we show basal plane activation of 1T' molybdenum disulfide and a lowering of ΔGH from +1.6 eV for 2H to +0.18 eV for 1T', comparable to 2H molybdenum disulfide edges on Au(111), one of the most active hydrogen evolution catalysts known.

  15. Understanding catalysis in a multiphasic two-dimensional transition metal dichalcogenide.

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chou, Stanley Shihyao; Sai, Na; Lu, Ping; Coker, Eric Nicholas; Liu, Sheng; Artyushkova, Kateryna; Luk, Ting S.; Kaehr, Bryan James; Brinker, C. Jeffrey

    2015-10-07

    Establishing processing–structure–property relationships for monolayer materials is crucial for a range of applications spanning optics, catalysis, electronics and energy. Presently, for molybdenum disulfide, a promising catalyst for artificial photosynthesis, considerable debate surrounds the structure/property relationships of its various allotropes. Here we unambiguously solve the structure of molybdenum disulfide monolayers using high-resolution transmission electron microscopy supported by density functional theory and show lithium intercalation to direct a preferential transformation of the basal plane from 2H (trigonal prismatic) to 1T' (clustered Mo). These changes alter the energetics of molybdenum disulfide interactions with hydrogen (ΔGH), and, with respect to catalysis, the 1T' transformationmore » renders the normally inert basal plane amenable towards hydrogen adsorption and hydrogen evolution. Furthermore, we show basal plane activation of 1T' molybdenum disulfide and a lowering of ΔGH from +1.6 eV for 2H to +0.18 eV for 1T', comparable to 2H molybdenum disulfide edges on Au(111), one of the most active hydrogen evolution catalysts known.« less

  16. Barrierless proton transfer across weak CH⋯O hydrogen bonds in dimethyl ether dimer

    SciTech Connect (OSTI)

    Yoder, Bruce L. West, Adam H. C.; Signorell, Ruth; Bravaya, Ksenia B.; Bodi, Andras; Sztáray, Bálint

    2015-03-21

    We present a combined computational and threshold photoelectron photoion coincidence study of two isotopologues of dimethyl ether, (DME − h{sub 6}){sub n} and (DME − d{sub 6}){sub n}n = 1 and 2, in the 9–14 eV photon energy range. Multiple isomers of neutral dimethyl ether dimer were considered, all of which may be present, and exhibited varying C–H⋯O interactions. Results from electronic structure calculations predict that all of them undergo barrierless proton transfer upon photoionization to the ground electronic state of the cation. In fact, all neutral isomers were found to relax to the same radical cation structure. The lowest energy dissociative photoionization channel of the dimer leads to CH{sub 3}OHCH{sub 3}{sup +} by the loss of CH{sub 2}OCH{sub 3} with a 0 K appearance energy of 9.71 ± 0.03 eV and 9.73 ± 0.03 eV for (DME − h{sub 6}){sub 2} and deuterated (DME − d{sub 6}){sub 2}, respectively. The ground state threshold photoelectron spectrum band of the dimethyl ether dimer is broad and exhibits no vibrational structure. Dimerization results in a 350 meV decrease of the valence band appearance energy, a 140 meV decrease of the band maximum, thus an almost twofold increase in the ground state band width, compared with DME − d{sub 6} monomer.

  17. The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Olek, Anna T.; Rayon, Catherine; Makowski, Lee; Kim, Hyung Rae; Ciesielski, Peter; Badger, John; Paul, Lake N.; Ghosh, Subhangi; Kihara, Daisuke; Crowley, Michael; et al

    2014-07-10

    Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice (Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongatedmore » structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. As a result, the arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize.« less

  18. Receptor expression is essential for proliferation induced by dimerized Jak kinases

    SciTech Connect (OSTI)

    Fujii, Hodaka

    2008-06-13

    Two members of Jak kinases, Jak1 and Jak3, are associated with the cytoplasmic domains of the interleukin-2 (IL-2) receptor (IL-2R) {beta} chain (IL-2R{beta}) and the common cytokine receptor {gamma} chain ({gamma}c), respectively, and accumulating evidence indicates their functional importance in IL-2 signaling. Here, I showed that coumermycin-induced chemical heterodimerization of Jak1 and Jak3 but not homodimerization of Jak1 or Jak3 induces cell proliferation of an IL-2R-reconstituted cell line. In this regard, expression of IL-2R{beta} was essential for cell proliferation by chemical heterodimerization of Jak1 and Jak3, indicating that dimerized Jak1 and Jak3 induce heterodimerization of IL-2R{beta} and {gamma}c, which may activate receptor-bound signaling molecules. Previous reports using chemical dimerization suggest that dimerization of Jak kinases is sufficient to induce cell proliferation. The present study indicates that re-evaluation of this conclusion is necessary and that interpretation of functional analysis of signaling molecules using chemical dimerizers needs more careful assessment.

  19. The structure of the catalytic domain of a plant cellulose synthase and its assembly into dimers

    SciTech Connect (OSTI)

    Olek, Anna T.; Rayon, Catherine; Makowski, Lee; Kim, Hyung Rae; Ciesielski, Peter; Badger, John; Paul, Lake N.; Ghosh, Subhangi; Kihara, Daisuke; Crowley, Michael; Himmel, Michael E.; Bolin, Jeffrey T.; Carpita, Nicholas C.

    2014-07-10

    Cellulose microfibrils are para-crystalline arrays of several dozen linear (1→4)-β-d-glucan chains synthesized at the surface of the cell membrane by large, multimeric complexes of synthase proteins. Recombinant catalytic domains of rice (Oryza sativa) CesA8 cellulose synthase form dimers reversibly as the fundamental scaffold units of architecture in the synthase complex. Specificity of binding to UDP and UDP-Glc indicates a properly folded protein, and binding kinetics indicate that each monomer independently synthesizes single glucan chains of cellulose, i.e., two chains per dimer pair. In contrast to structure modeling predictions, solution x-ray scattering studies demonstrate that the monomer is a two-domain, elongated structure, with the smaller domain coupling two monomers into a dimer. The catalytic core of the monomer is accommodated only near its center, with the plant-specific sequences occupying the small domain and an extension distal to the catalytic domain. This configuration is in stark contrast to the domain organization obtained in predicted structures of plant CesA. As a result, the arrangement of the catalytic domain within the CesA monomer and dimer provides a foundation for constructing structural models of the synthase complex and defining the relationship between the rosette structure and the cellulose microfibrils they synthesize.

  20. Engineering of a novel Ca{sup 2+}-regulated kinesin molecular motor using a calmodulin dimer linker

    SciTech Connect (OSTI)

    Shishido, Hideki; Maruta, Shinsaku

    2012-06-29

    Highlights: Black-Right-Pointing-Pointer Engineered kinesin-M13 and calmodulin involving single cysteine were prepared. Black-Right-Pointing-Pointer CaM mutant was cross-linked to dimer by bifunctional thiol reactive reagent. Black-Right-Pointing-Pointer Kinesin-M13 was dimerized via CaM dimer in the presence of calcium. Black-Right-Pointing-Pointer Function of the engineered kinesin was regulated by a Ca{sup 2+}-calmodulin dimer linker. -- Abstract: The kinesin-microtubule system holds great promise as a molecular shuttle device within biochips. However, one current barrier is that such shuttles do not have 'on-off' control of their movement. Here we report the development of a novel molecular motor powered by an accelerator and brake system, using a kinesin monomer and a calmodulin (CaM) dimer. The kinesin monomer, K355, was fused with a CaM target peptide (M13 peptide) at the C-terminal part of the neck region (K355-M13). We also prepared CaM dimers using CaM mutants (Q3C), (R86C), or (A147C) and crosslinkers that react with cysteine residues. Following induction of K355-M13 dimerization with CaM dimers, we measured K355-M13 motility and found that it can be reversibly regulated in a Ca{sup 2+}-dependent manner. We also found that velocities of K355-M13 varied depending on the type and crosslink position of the CaM dimer used; crosslink length also had a moderate effect on motility. These results suggest Ca{sup 2+}-dependent dimerization of K355-M13 could be used as a novel molecular shuttle, equipped with an accelerator and brake system, for biochip applications.

  1. CATALYTIC INTERACTIONS OF RHODIUM, RUTHENIUM, AND MERCURY DURING SIMULATED DWPF CPC PROCESSING WITH HYDROGEN GENERATION

    SciTech Connect (OSTI)

    Koopman, D

    2008-10-09

    Simulations of the Defense Waste Processing Facility (DWPF) Chemical Processing Cell (CPC) vessels were performed as part of the ongoing investigation into catalytic hydrogen generation. Rhodium, ruthenium, and mercury have been identified as the principal elemental factors affecting the peak hydrogen generation rate in the DWPF Sludge Receipt and Adjustment Tank (SRAT) for a given acid addition. The primary goal of this study is to identify any significant interactions between the three factors. Noble metal concentrations were similar to recent sludge batches. Rh ranged from 0.0026-0.013% and Ru ranged from 0.010-0.050% in the dried sludge solids, while initial Hg ranged from 0.5-2.5 wt%. An experimental matrix was developed to ensure that the existence of statistically significant two-way interactions could be determined without confounding of the main effects with the two-way interaction effects. The nominal matrix design consisted of twelve SRAT cycles. Testing included: a three factor (Rh, Ru, and Hg) study at two levels per factor (eight runs), two duplicate midpoint runs, and two additional replicate runs to assess reproducibility away from the midpoint. Midpoint testing can identify potential quadratic effects from the three factors. A single sludge simulant was used for all tests. Acid addition was kept effectively constant except to compensate for variations in the starting mercury concentration. Six Slurry Mix Evaporator (SME) cycles were performed to supplement the SME hydrogen generation database. Some of the preliminary findings from this study include: (1) Rh was linked to the maximum SRAT hydrogen generation rate in the first two hours after acid addition in preliminary statistical modeling. (2) Ru was linked conclusively to the maximum SRAT hydrogen generation rate in the last four hours of reflux in preliminary statistical modeling. (3) Increasing the ratio of Hg/Rh shifted the noble metal controlling the maximum SRAT hydrogen generation rate from Rh to Ru when Ru was at its fission yield ratio to Rh. (4) The inhibiting effect of Hg on hydrogen generation apparently does not require much mercury in terms of moles Hg/mole Rh (or Ru). Once the initial impact is realized, the benefit of additional Hg in reducing the hydrogen generation rate was minimal. Sludge Batch 3 and 4 simulant test data confirm this. (5) Low Hg runs do not necessarily bound high Hg runs for the maximum hydrogen generation rate over the full SRAT-SME cycle. Two of the four Rh-Ru combinations had a cross-over point where the hydrogen generation rate in high Hg run went from always lower to always higher than in the low Hg run. One cross-over was in the SRAT and one was in the SME. Maximum hydrogen generation rates in the high Hg runs could exceed the maximum hydrogen generation rates from the low Hg runs. (6) SME cycle hydrogen generation rates during the first decon canister dewatering period were similar to the rates at the end of the SRAT reflux period. (7) Corrosion of 400 series stainless steel shafts significantly impacted the hydrogen generation rate in two runs. (8) Preliminary data analysis indicates that several additional SRAT runs are needed to replace suspect data in the original set of twelve runs. A more detailed statistical evaluation is expected to occur once replacement run data from several additional SRAT runs has been obtained.

  2. Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO2

    SciTech Connect (OSTI)

    Appel, Aaron M.; Bercaw, John E.; Bocarsly, Andrew B.; Dobbek, Holger; DuBois, Daniel L.; Dupuis, Michel; Ferry, James G.; Fujita, Etsuko; Hille, Russ; Kenis, Paul; Kerfeld, Cheryl A.; Morris, Robert H.; Peden, Charles HF; Portis, Archie; Ragsdale, Steve; Rauchfuss, Thomas B.; Reek, Joost; Seefeldt, Lance C.; Thauer, Rudolf K.; Waldrop, Grover L.

    2013-08-14

    Our central premise is that catalytic scientists can learn by studying how these important metabolic processes occur in nature. Complementarily, biochemists can learn by studying how catalytic scientists view these same chemical transformations promoted by synthetic catalysts. From these studies, hypotheses can be developed and tested through manipulation of enzyme structure and by synthesizing simple molecular catalysts to incorporate different structural features of the enzymes. It is hoped that these studies will lead to new and useful concepts in catalyst design for fuel production and utilization. This paper describes the results of a workshop held to explore these concepts in regard to the development of new and more efficient catalytic processes for the conversion of CO2 to a variety of carbon-based fuels. The organization of this overview/review is as follows: 1) The first section briefly explores how interactions between the catalysis and biological communities have been fruitful in developing new catalysts for the reduction of protons to hydrogen, the simplest fuel generation reaction. 2) The second section assesses the state of the art in both biological and chemical reduction of CO2 by two electrons to form either carbon monoxide (CO) or formate (HCOO-). It also attempts to identify common principles between biological and synthetic catalysts and productive areas for future research. 3) The third section explores both biological and chemical processes that result in the reduction of CO2 beyond the level of CO and formate, again seeking to identify common principles and productive areas of future research. 4) The fourth section explores the formation of carbon-carbon bonds in biological and chemical systems in the same vein as the other sections. 5) A fifth section addresses the role of non-redox reactions of CO2 in biological systems and their role in carbon metabolism, with a parallel discussion of chemical systems. 6) In section 6, the topics of electrode modification, photochemical systems, and tandem catalysis are briefly discussed. These areas may be important for developing practical systems for CO2 reduction, and they share the common theme of coupling chemical reactions. 7) Section 7 describes some of the crosscutting activities that are critical for advancing the science underpinning catalyst development. 8) The last section attempts to summarize common issues in biological and chemical catalysis and to identify challenges that must be addressed to achieve practical catalysts that are suitable for the reduction of CO2 to fuels.

  3. Wavelet-based surrogate time series for multiscale simulation of heterogeneous catalysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Savara, Aditya Ashi; Daw, C. Stuart; Xiong, Qingang; Gur, Sourav; Danielson, Thomas L.; Hin, Celine N.; Pannala, Sreekanth; Frantziskonis, George N.

    2016-01-28

    We propose a wavelet-based scheme that encodes the essential dynamics of discrete microscale surface reactions in a form that can be coupled with continuum macroscale flow simulations with high computational efficiency. This makes it possible to simulate the dynamic behavior of reactor-scale heterogeneous catalysis without requiring detailed concurrent simulations at both the surface and continuum scales using different models. Our scheme is based on the application of wavelet-based surrogate time series that encodes the essential temporal and/or spatial fine-scale dynamics at the catalyst surface. The encoded dynamics are then used to generate statistically equivalent, randomized surrogate time series, which canmore » be linked to the continuum scale simulation. As a result, we illustrate an application of this approach using two different kinetic Monte Carlo simulations with different characteristic behaviors typical for heterogeneous chemical reactions.« less

  4. A mean-field monomer-dimer model with attractive interaction: Exact solution and rigorous results

    SciTech Connect (OSTI)

    Alberici, D. Contucci, P. Mingione, E.

    2014-06-15

    A mean-field monomer-dimer model which includes an attractive interaction among both monomers and dimers is introduced and its exact solution rigorously derived. The Heilmann-Lieb method for the pure hard-core interacting case is used to compute upper and lower bounds for the pressure. The bounds are shown to coincide in the thermodynamic limit for a suitable choice of the monomer density m. The computation of the monomer density is achieved by solving a consistency equation in the phase space (h, J), where h tunes the monomer potential and J the attractive potential. The critical point and exponents are computed and show that the model is in the mean-field ferromagnetic universality class.

  5. Photo-induced strengthening of weak bonding in noble gas dimers

    SciTech Connect (OSTI)

    Miyamoto, Yoshiyuki; Miyazaki, Takehide; Rubio, Angel

    2014-05-19

    We demonstrate through extensive first-principles time-dependent density functional calculations that attractive van der Waals interaction between closed-shell atoms can be enhanced by light with constant spatial intensity. We illustrate this general phenomenon for a He dimer as a prototypical case of complex van der Waals interactions and show that when excited by light with a frequency close to the 1s → 2p He-atomic transition, an attractive force larger than 7 pN is produced. This force gain is manifested as a larger acceleration of He-He contraction under an optical field. The concerted dynamical motions of the He atoms together with polarity switching of the charge-induced dipole cause the contraction of the dimer. These findings are relevant for the photo-induced control of weakly bonded molecular species, either in gas phase or in solution.

  6. Modeling theta-theta Interactions with the Effective Fragment Potential Method: The Benzene Dimer and Substituents

    SciTech Connect (OSTI)

    Toni Smithl; Lyudmila V. Slipchenko; Mark S. Gordon

    2008-02-27

    This study compares the results of the general effective fragment potential (EFP2) method to the results of a previous combined coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] and symmetry-adapted perturbation theory (SAPT) study [Sinnokrot and Sherrill, J. Am. Chem. Soc., 2004, 126, 7690] on substituent effects in {pi}-{pi} interactions. EFP2 is found to accurately model the binding energies of the benzene-benzene, benzene-phenol, benzene-toluene, benzene-fluorobenzene, and benzene-benzonitrile dimers, as compared with high-level methods [Sinnokrot and Sherrill, J. Am. Chem. Soc., 2004, 126, 7690], but at a fraction of the computational cost of CCSD(T). In addition, an EFP-based Monte Carlo/simulated annealing study was undertaken to examine the potential energy surface of the substituted dimers.

  7. Is It Homogeneous or Heterogeneous Catalysis Derived from [RhCp*Cl2]2? In Operando-XAFS, Kinetic and Crucial Kinetic Poisoning Evidence for Subnanometer Rh4 Cluster-Based Benzene Hydrogenation Catalysis

    SciTech Connect (OSTI)

    Bayram, Ercan; Linehan, John C.; Fulton, John L.; Roberts, John A.; Szymczak, Nathaniel; Smurthwaite, Tricia D.; Ozkar, Saim; Balasubramanian, Mahalingam; Finke, Richard G.

    2011-11-23

    Determining the true, kinetically dominant catalytically active species, in the classic benzene hydrogenation system pioneered by Maitlis and co-workers 34 years ago starting with [RhCp*Cl2]2 (Cp* = [{eta}5-C5(CH3)5]), has proven to be one of the most challenging case studies in the quest to distinguish single-metal-based 'homogeneous' from polymetallic, 'heterogeneous' catalysis. The reason, this study will show, is the previous failure to use the proper combination of (i) operando spectroscopy to determine the dominant form(s) of the precatalyst's mass under catalysis (i.e., operating) conditions, plus then and crucially also (ii) the previous lack of the necessary kinetic studies, catalysis being a 'wholly kinetic phenomenon' as J. Halpern long ago noted. An important contribution from this study will be to reveal the power of quantitiative kinetic poisoning experiments for distinguishing single-metal, or in this case subnanometer Rh4 cluster-based catalysis from larger, polymetallic Rh(0)n nanoparticle catalysis, at least under favorable conditions. The combined operando-XAFS (X-ray absorption fine structure) spectroscopy and kinetic evidences provide a compelling case for Rh4-based, with average stoichiometry 'Rh4Cp*2.4Cl4Hc', benzene hydrogenation catalysis in 2-propanol with added Et3N and at 100 C and 50 atm initial H2 pressure. The results also reveal, however, that if even ca. 1.4% of the total soluble Rh(0)n had formed nanoparticles, then those Rh(0)n nanoparticles would have been able to account for all the observed benzene hydrogenation catalytic rate (using commercial, ca. 2 nm, polyethyleneglycol-dodecylether hydrosol stabilized Rh(0)n nanoparticles as a model system). The results 'especially the poisoning methodology developed and employed' are of significant, broader interest since determining the nature of the true catalyst continues to be a central, often vexing issue in any and all catalytic reactions. The results are also of fundamental interest in that they add to a growing body of evidence indicating that certain, appropriately ligated, coordinatively unsaturated, subnanometer M4 transition-metal clusters can be relatively robust catalysts. Also demonstrated herein is that Rh4 clusters are poisoned by Hg(0), demonstrating for the first time that the classic Hg(0) poisoning test of 'homogeneous' vs 'heterogeneous'catalysts cannot distinguish Rh4-based subnanometer catalysts from Rh(0)n nanoparticle catalysts, at least for the present examples of these two specific, Rh-based catalysts.

  8. The HPr Proteins from the Thermophile Bacillus stearothermophilus Can Form Domain-swapped Dimers

    SciTech Connect (OSTI)

    Sridharan, Sudharsan; Razvi, Abbas; Scholtz, J. Martin; Sacchettini, James C. (TAM)

    2010-07-20

    The study of proteins from extremophilic organisms continues to generate interest in the field of protein folding because paradigms explaining the enhanced stability of these proteins still elude us and such studies have the potential to further our knowledge of the forces stabilizing proteins. We have undertaken such a study with our model protein HPr from a mesophile, Bacillus subtilis, and a thermophile, Bacillus stearothermophilus. We report here the high-resolution structures of the wild-type HPr protein from the thermophile and a variant, F29W. The variant proved to crystallize in two forms: a monomeric form with a structure very similar to the wild-type protein as well as a domain-swapped dimer. Interestingly, the structure of the domain-swapped dimer for HPr is very different from that observed for a homologous protein, Crh, from B. subtilis. The existence of a domain-swapped dimer has implications for amyloid formation and is consistent with recent results showing that the HPr proteins can form amyloid fibrils. We also characterized the conformational stability of the thermophilic HPr proteins using thermal and solvent denaturation methods and have used the high-resolution structures in an attempt to explain the differences in stability between the different HPr proteins. Finally, we present a detailed analysis of the solution properties of the HPr proteins using a variety of biochemical and biophysical methods.

  9. The Structure of the Poxvirus A33 Protein Reveals a Dimer of Unique C-Type Lectin-Like Domains

    SciTech Connect (OSTI)

    Su, Hua-Poo; Singh, Kavita; Gittis, Apostolos G.; Garboczi, David N. (NIH)

    2010-11-03

    The current vaccine against smallpox is an infectious form of vaccinia virus that has significant side effects. Alternative vaccine approaches using recombinant viral proteins are being developed. A target of subunit vaccine strategies is the poxvirus protein A33, a conserved protein in the Chordopoxvirinae subfamily of Poxviridae that is expressed on the outer viral envelope. Here we have determined the structure of the A33 ectodomain of vaccinia virus. The structure revealed C-type lectin-like domains (CTLDs) that occur as dimers in A33 crystals with five different crystal lattices. Comparison of the A33 dimer models shows that the A33 monomers have a degree of flexibility in position within the dimer. Structural comparisons show that the A33 monomer is a close match to the Link module class of CTLDs but that the A33 dimer is most similar to the natural killer (NK)-cell receptor class of CTLDs. Structural data on Link modules and NK-cell receptor-ligand complexes suggest a surface of A33 that could interact with viral or host ligands. The dimer interface is well conserved in all known A33 sequences, indicating an important role for the A33 dimer. The structure indicates how previously described A33 mutations disrupt protein folding and locates the positions of N-linked glycosylations and the epitope of a protective antibody.

  10. Vapor Synthesis and Thermal Modification of Supportless Platinum–Ruthenium Nanotubes and Application as Methanol Electrooxidation Catalysts

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Atkinson III, Robert W.; Unocic, Raymond R.; Unocic, Kinga A.; Veith, Gabriel M.; Zawodzinski, Jr., Thomas A.; Papandrew, Alexander B.

    2015-04-23

    Metallic, mixed-phase, and alloyed bimetallic Pt-Ru nanotubes were synthesized by a novel route based on the sublimation of metal acetylacetonate precursors and their subsequent vapor deposition within anodic alumina templates. Nanotube architectures were tuned by thermal annealing treatments. As-synthesized nanotubes are composed of nanoparticulate, metallic platinum and hydrous ruthenium oxide whose respective thicknesses depend on the sample chemical composition. The Pt-decorated, hydrous Ru oxide nanotubes may be thermally annealed to promote a series of chemical and physical changes to the nanotube structures including alloy formation, crystallite growth and morphological evolution. Annealed Pt-Ru alloy nanotubes and their as-synthesized analogs demonstrate relativelymore » high specific activities for the oxidation of methanol. As-synthesized, mixed-phase Pt-Ru nanotubes (0.39 mA/cm2) and metallic alloyed Pt64Ru36NTs (0.33 mA/cm2) have considerably higher area-normalized activities than PtRu black (0.22 mA/cm2) at 0.65 V vs. RHE.« less

  11. Vapor Synthesis and Thermal Modification of Supportless Platinum-Ruthenium Nanotubes and Application as Methanol Electrooxidation Catalysts

    SciTech Connect (OSTI)

    Atkinson III, Robert; Unocic, Raymond R; Unocic, Kinga A; Veith, Gabriel M; Papandrew, Alexander B; Zawodzinski, Thomas A

    2015-01-01

    Metallic, mixed-phase, and alloyed bimetallic Pt-Ru nanotubes were synthesized by a novel route based on the sublimation of metal acetylacetonate precursors and their subsequent vapor deposition within anodic alumina templates. Nanotube architectures were tuned by thermal annealing treatments. As-synthesized nanotubes are composed of nanoparticulate, metallic platinum and hydrous ruthenium oxide whose respective thicknesses depend on the sample chemical composition. The Pt-decorated, hydrous Ru oxide nanotubes may be thermally annealed to promote a series of chemical and physical changes to the nanotube structures including alloy formation, crystallite growth and morphological evolution. Annealed Pt-Ru alloy nanotubes and their as-synthesized analogs demonstrate relatively high specific activities for the oxidation of methanol. As-synthesized, mixed-phase Pt-Ru nanotubes (0.39 mA/cm2) and metallic alloyed Pt64Ru36NTs (0.33 mA/cm2) have considerably higher area-normalized activities than PtRu black (0.22 mA/cm2) at 0.65 V vs. RHE.

  12. Adsorption of Ruthenium, Rhodium and Palladium from Simulated High-Level Liquid Waste by Highly Functional Xerogel - 13286

    SciTech Connect (OSTI)

    Onishi, Takashi [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan)] [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan); Koyama, Shin-ichi [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan)] [Fukushima Fuels and Materials Department O-arai Research and Development Center Japan Atomic Energy Agency, Narita-cho 4002, O-arai-machi, Ibaraki, 311-1393 (Japan); Mimura, Hitoshi [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University Aramaki-Aza-Aoba 6-6-01-2,Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 (Japan)] [Dept. of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University Aramaki-Aza-Aoba 6-6-01-2,Aoba-ku, Sendai-shi, Miyagi-ken, 980-8579 (Japan)

    2013-07-01

    Fission products are generated by fission reactions in nuclear fuel. Platinum group (Pt-G) elements, such as palladium (Pd), rhodium (Rh) and ruthenium (Ru), are also produced. Generally, Pt-G elements play important roles in chemical and electrical industries. Highly functional xerogels have been developed for recovery of these useful Pt-G elements from high - level radioactive liquid waste (HLLW). An adsorption experiment from simulated HLLW was done by the column method to study the selective adsorption of Pt-G elements, and it was found that not only Pd, Rh and Ru, but also nickel, zirconium and tellurium were adsorbed. All other elements were not adsorbed. Adsorbed Pd was recovered by washing the xerogel-packed column with thiourea solution and thiourea - nitric acid mixed solution in an elution experiment. Thiourea can be a poison for automotive exhaust emission system catalysts, so it is necessary to consider its removal. Thermal decomposition and an acid digestion treatment were conducted to remove sulfur in the recovered Pd fraction. The relative content of sulfur to Pd was decreased from 858 to 0.02 after the treatment. These results will contribute to design of the Pt-G element separation system. (authors)

  13. Sulfation of metal-organic framework: Opportunities for acid catalysis and proton conductivity

    SciTech Connect (OSTI)

    Goesten, M.G.; Stavitski, E.; Juan-Alcaniz, J.; Ramos-Fernandez, E.V.; Sai Sankar Gupta, K.B.; van Bekkum, H.; Gascon, J. and Kapteijn, F.

    2011-05-24

    A new post-functionalization method for metal-organic frameworks (MOFs) has been developed to introduce acidity for catalysis. Upon treatment with a mixture of triflic anhydride and sulfuric acid, chemically stable MOF structures MIL-101(Cr) and MIL-53(Al) can be sulfated, resulting in a Broensted sulfoxy acid group attached to up to 50% of the aromatic terephthalate linkers of the structure. The sulfated samples have been extensively characterized by solid-state NMR, XANES, and FTIR spectroscopy. The functionalized acidic frameworks show catalytic activity similar to that of acidic polymers like Nafion{reg_sign} display in the esterification of n-butanol with acetic acid (TOF {approx} 1 min{sup -1} {at} 343 K). Water adsorbs strongly up to 4 molecules per sulfoxy acid group, and an additional 2 molecules are taken up at lower temperatures in the 1-D pore channels of S-MIL-53(Al). The high water content and Broensted acidity provide the structure S-MIL-53(Al) a high proton conductivity up to moderate temperatures.

  14. Accurate potential energy, dipole moment curves, and lifetimes of vibrational states of heteronuclear alkali dimers

    SciTech Connect (OSTI)

    Fedorov, Dmitry A.; Varganov, Sergey A.; Derevianko, Andrei

    2014-05-14

    We calculate the potential energy curves, the permanent dipole moment curves, and the lifetimes of the ground and excited vibrational states of the heteronuclear alkali dimers XY (X, Y = Li, Na, K, Rb, Cs) in the X{sup 1}?{sup +} electronic state using the coupled cluster with singles doubles and triples method. All-electron quadruple-? basis sets with additional core functions are used for Li and Na, and small-core relativistic effective core potentials with quadruple-? quality basis sets are used for K, Rb, and Cs. The inclusion of the coupled cluster non-perturbative triple excitations is shown to be crucial for obtaining the accurate potential energy curves. A large one-electron basis set with additional core functions is needed for the accurate prediction of permanent dipole moments. The dissociation energies are overestimated by only 14 cm{sup ?1} for LiNa and by no more than 114 cm{sup ?1} for the other molecules. The discrepancies between the experimental and calculated harmonic vibrational frequencies are less than 1.7 cm{sup ?1}, and the discrepancies for the anharmonic correction are less than 0.1 cm{sup ?1}. We show that correlation between atomic electronegativity differences and permanent dipole moment of heteronuclear alkali dimers is not perfect. To obtain the vibrational energies and wave functions the vibrational Schrdinger equation is solved with the B-spline basis set method. The transition dipole moments between all vibrational states, the Einstein coefficients, and the lifetimes of the vibrational states are calculated. We analyze the decay rates of the vibrational states in terms of spontaneous emission, and stimulated emission and absorption induced by black body radiation. In all studied heteronuclear alkali dimers the ground vibrational states have much longer lifetimes than any excited states.

  15. Enhanced dimer relaxation in an atomic and molecular Bose-Einstein condensate

    SciTech Connect (OSTI)

    Braaten, Eric; Hammer, H.-W.

    2004-10-01

    We derive a universal formula for the rate constant {beta} for relaxation of a shallow dimer into deeply-bound diatomic molecules in the case of atoms with a large scattering length a. We show that {beta} is determined by a and by 2 three-body parameters that also determine the binding energies and widths of Efimov states. The rate constant {beta} scales like ({Dirac_h}/2{pi})a/m near the resonance, but the coefficient is a periodic function of ln(a) that may have resonant enhancement at values of a that differ by multiples of 22.7.

  16. Dimeric c-di-GMP is required for post-translational regulation of alginate production in Pseudomonas aeruginosa

    SciTech Connect (OSTI)

    Whitney, John C.; Robinson, Howard; Whitfield, Gregory B.; Marmont, Lindsey S.; Yip, Patrick; Neculai, A. Mirela; Lobsanov, Yuri D.; Ohman, Dennis E.; Howell, P. Lynne

    2015-05-15

    Pseudomonas aeruginosa is an opportunistic human pathogen that secretes the exopolysaccharide alginate during infection of the respiratory tract of individuals afflicted with cystic fibrosis and chronic obstructive pulmonary disease. Among the proteins required for alginate production, Alg44 has been identified as an inner membrane protein whose bis-(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) binding activity post-translationally regulates alginate secretion. In this study, we report the 1.8 Å crystal structure of the cytoplasmic region of Alg44 in complex with dimeric self-intercalated c-di-GMP and characterize its dinucleotide-binding site using mutational analysis. The structure shows that the c-di-GMP binding region of Alg44 adopts a PilZ domain fold with a dimerization mode not previously observed for this family of proteins. Moreover, calorimetric binding analysis of residues in the c-di-GMP binding site demonstrate that mutation of Arg-17 and Arg-95 alters the binding stoichiometry between c-di-GMP and Alg44 from 2:1 to 1:1. Introduction of these mutant alleles on the P. aeruginosa chromosome show that the residues required for binding of dimeric c-di-GMP in vitro are also required for efficient alginate production in vivo. Our results suggest that the dimeric form of c-di-GMP represents the biologically active signaling molecule needed for the secretion of an important virulence factor produced by P. aeruginosa.

  17. Dimeric c-di-GMP is required for post-translational regulation of alginate production in Pseudomonas aeruginosa

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Whitney, John C.; Robinson, Howard; Whitfield, Gregory B.; Marmont, Lindsey S.; Yip, Patrick; Neculai, A. Mirela; Lobsanov, Yuri D.; Ohman, Dennis E.; Howell, P. Lynne

    2015-05-15

    Pseudomonas aeruginosa is an opportunistic human pathogen that secretes the exopolysaccharide alginate during infection of the respiratory tract of individuals afflicted with cystic fibrosis and chronic obstructive pulmonary disease. Among the proteins required for alginate production, Alg44 has been identified as an inner membrane protein whose bis-(3',5')-cyclic dimeric guanosine monophosphate (c-di-GMP) binding activity post-translationally regulates alginate secretion. In this study, we report the 1.8 Å crystal structure of the cytoplasmic region of Alg44 in complex with dimeric self-intercalated c-di-GMP and characterize its dinucleotide-binding site using mutational analysis. The structure shows that the c-di-GMP binding region of Alg44 adopts a PilZmore » domain fold with a dimerization mode not previously observed for this family of proteins. Moreover, calorimetric binding analysis of residues in the c-di-GMP binding site demonstrate that mutation of Arg-17 and Arg-95 alters the binding stoichiometry between c-di-GMP and Alg44 from 2:1 to 1:1. Introduction of these mutant alleles on the P. aeruginosa chromosome show that the residues required for binding of dimeric c-di-GMP in vitro are also required for efficient alginate production in vivo. Our results suggest that the dimeric form of c-di-GMP represents the biologically active signaling molecule needed for the secretion of an important virulence factor produced by P. aeruginosa.« less

  18. Magnons and continua in a magnetized and dimerized spin - 12 chain

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Stone, M. B.; Chen, Y.; Reich, D. H.; Broholm, C.; Xu, G.; Copley, J. R. D.; Cook, J. C.

    2014-09-29

    We examine the magnetic field dependent excitations of the dimerized spin -1/2 chain, copper nitrate, with antiferromagnetic intra-dimer exchangemore » $J_1=0.44$ (1) meV and exchange alternation $$\\alpha=J_2/J_1=0.26$$ (2). Magnetic excitations in three distinct regimes of magnetization are probed through inelastic neutron scattering at low temperatures. At low and high fields there are three and two long-lived magnon-like modes, respectively. The number of modes and the anti-phase relationship between the wave-vector dependent energy and intensity of magnon scattering reflect the distinct ground states: A singlet ground state at low fields $$\\mu_0H < \\mu_0H_{c1} = 2.8$$ T and an $S_z=1/2$ product state at high fields $$\\mu_0H > \\mu_0H_{c2} = 4.2$$ T. Lastly, in the intermediate field regime, a continuum of scattering for $$\\hbar\\omega\\approx J_1$$ is indicative of a strongly correlated gapless quantum state without coherent magnons.« less

  19. PHOTODISSOCIATION OF THE DIACETYLENE DIMER AND IMPLICATIONS FOR HYDROCARBON GROWTH IN TITAN'S ATMOSPHERE

    SciTech Connect (OSTI)

    Huang Cunshun; Silva, Ruchira; Gichuhi, Wilson K.; Suits, Arthur G.; Zhang Fangtong; Kaiser, Ralf I.; Kislov, Vadim V.; Mebel, Alexander M.

    2010-05-10

    The surface of Titan is obscured by multiple aerosol layers whose composition and formation mechanism have remained poorly understood. These organic haze layers are believed to arise from photolysis and electron impact triggered chemistry in the dense nitrogen (N{sub 2}) and methane (CH{sub 4}) atmosphere involving highly unsaturated hydrocarbon molecules such as acetylene (HCCH), diacetylene (HCCCCH), and triacetylene (HCCCCCCH). Here we show via laboratory studies combined with electronic structure calculations that the photodissociation of the diacetylene dimer ((HCCCCH){sub 2}) readily initiates atomic hydrogen loss and atomic hydrogen transfer reactions forming two prototypes of resonantly stabilized free radicals, C{sub 4}H{sub 3} and C{sub 8}H{sub 3}, respectively. These structures represent hydrogenated polyynes which can neither be synthesized via traditional photodissociation pathways of the monomer nor via hydrogen addition to the polyynes. The photodissociation dynamics of mixed dimers involving acetylene, diacetylene, and even triacetylene present a novel, hitherto overlooked reaction class and show the potential to synthesize more complex, resonantly stabilized free radicals considered to be major building blocks to polycyclic aromatic hydrocarbons in Titan's low-temperature atmosphere.

  20. Process for producing high purity isoolefins and dimers thereof by dissociation of ethers

    DOE Patents [OSTI]

    Smith, L.A. Jr.; Jones, E.M. Jr.; Hearn, D.

    1984-05-08

    Alkyl tertiary butyl ether or alkyl tertiary amyl ether is dissociated by vapor phase contact with a cation acidic exchange resin at temperatures in the range of 150 to 250 F at LHSV of 0.1 to 20 to produce a stream consisting of unreacted ether, isobutene or isoamylene and an alcohol corresponding to the alkyl radical. After the alcohol is removed, the ether/isoolefin stream may be fractionated to obtain a high purity isoolefin (99+%) or the ether/isoolefin stream can be contacted in liquid phase with a cation acidic exchange resin to selectively dimerize the isoolefin in a highly exothermic reaction, followed by fractionation of the dimerization product to produce high purity diisoolefin (97+%). In the case where the alkyl is C[sub 3] to C[sub 6] and the corresponding alcohol is produced on dissociation of the ether, combined dissociation-distillation may be carried out such that isoolefin is the overhead product and alcohol the bottom. 2 figs.

  1. Process for producing high purity isoolefins and dimers thereof by dissociation of ethers

    DOE Patents [OSTI]

    Smith, Jr., Lawrence A.; Jones, Jr., Edward M.; Hearn, Dennis

    1984-01-01

    Alkyl tertiary butyl ether or alkyl tertiary amyl ether is dissociated by vapor phase contact with a cation acidic exchange resin at temperatures in the range of 150.degree. to 250.degree. F. at LHSV of 0.1 to 20 to produce a stream consisting of unreacted ether, isobutene or isoamylene and an alcohol corresponding to the alkyl radical. After the alcohol is removed, the ether/isoolefin stream may be fractionated to obtain a high purity isoolefin (99+%) or the ether/isoolefin stream can be contacted in liquid phase with a cation acidic exchange resin to selectively dimerize the isoolefin in a highly exothermic reaction, followed by fractionation of the dimerization product to produce high purity diisoolefin (97+%). In the case where the alkyl is C.sub.3 to C.sub.6 and the corresponding alcohol is produced on dissociation of the ether, combined dissociation-distillation may be carried out such that isoolefin is the overhead product and alcohol the bottom.

  2. Excitonic splitting and coherent electronic energy transfer in the gas-phase benzoic acid dimer

    SciTech Connect (OSTI)

    Ottiger, Philipp; Leutwyler, Samuel

    2012-11-28

    The benzoic acid dimer, (BZA){sub 2}, is a paradigmatic symmetric hydrogen bonded dimer with two strong antiparallel hydrogen bonds. The excitonic S{sub 1}/S{sub 2} state splitting and coherent electronic energy transfer within supersonically cooled (BZA){sub 2} and its {sup 13}C-, d{sub 1}-, d{sub 2}-, and {sup 13}C/d{sub 1}- isotopomers have been investigated by mass-resolved two-color resonant two-photon ionization spectroscopy. The (BZA){sub 2}-(h-h) and (BZA){sub 2}-(d-d) dimers are C{sub 2h} symmetric, hence only the S{sub 2} Leftwards-Arrow S{sub 0} transition can be observed, the S{sub 1} Leftwards-Arrow S{sub 0} transition being strictly electric-dipole forbidden. A single {sup 12}C/{sup 13}C or H/D isotopic substitution reduces the symmetry of the dimer to C{sub s}, so that the isotopic heterodimers (BZA){sub 2}-{sup 13}C, (BZA){sub 2}-(h-d), (BZA){sub 2}-(h{sup 13}C-d), and (BZA){sub 2}-(h-d{sup 13}C) show both S{sub 1} Leftwards-Arrow S{sub 0} and S{sub 2} Leftwards-Arrow S{sub 0} bands. The S{sub 1}/S{sub 2} exciton splitting inferred is {Delta}{sub exc}= 0.94 {+-} 0.1 cm{sup -1}. This is the smallest splitting observed so far for any H-bonded gas-phase dimer. Additional isotope-dependent contributions to the splittings, {Delta}{sub iso}, arise from the change of the zero-point vibrational energy upon electronic excitation and range from {Delta}{sub iso}= 3.3 cm{sup -1} upon {sup 12}C/{sup 13}C substitution to 14.8 cm{sup -1} for carboxy H/D substitution. The degree of excitonic localization/delocalization can be sensitively measured via the relative intensities of the S{sub 1} Leftwards-Arrow S{sub 0} and S{sub 2} Leftwards-Arrow S{sub 0} origin bands; near-complete localization is observed even for a single {sup 12}C/{sup 13}C substitution. The S{sub 1}/ S{sub 2} energy gap of (BZA){sub 2} is {Delta}{sub calc}{sup exc}=11 cm{sup -1} when calculated by the approximate second-order perturbation theory (CC2) method. Upon correction for vibronic quenching, this decreases to {Delta}{sub vibron}{sup exc}=2.1 cm{sup -1} [P. Ottiger et al., J. Chem. Phys. 136, 174308 (2012)], in good agreement with the observed {Delta}{sub exc}= 0.94 cm{sup -1}. The observed excitonic splittings can be converted to exciton hopping times {tau}{sub exc}. For the (BZA){sub 2}-(h-h) homodimer {tau}{sub exc}= 18 ps, which is nearly 40 times shorter than the double proton transfer time of (BZA){sub 2} in its excited state [Kalkman et al., ChemPhysChem 9, 1788 (2008)]. Thus, the electronic energy transfer is much faster than the proton-transfer in (BZA){sub 2}{sup *}.

  3. Electrochemical Oxidation of H? Catalyzed by Ruthenium Hydride Complexes Bearing P?N? Ligands With Pendant Amines as Proton Relays

    SciTech Connect (OSTI)

    Liu, Tianbiao L.; Rakowski DuBois, Mary; DuBois, Daniel L.; Bullock, R. Morris

    2014-01-01

    Two Ru hydride complexes (Cp*Ru(PPh?NBn?)H, (1-H) and Cp*Ru(PtBu?NBn?)H, (2-H) supported by cyclic PR?NR'? ligands (Cp* = n?-C?Me?; 1,5-diaza-3,7-diphosphacyclooctane, where R = Ph or tBu and R' = Bn) have been synthesized and fully characterized. Both complexes are demonstrated to be electrocatalysts for oxidation of H? (1 atm, 22 C) in the presence of external base, DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). The turnover frequency of 2-H is 1.2 s-1, with an overpotential at Ecat/2 of 0.45 V, while catalysis by 1-H has a turnover frequency of 0.6 s-1 and an overpotential of 0.6 V at Ecat/2. Addition of H?O facilitates oxidation of H? by 2-H and increases its turnover frequency to 1.9 s-1 while , H?O slows down the catalysis by 1-H. The different effects of H?O for 1-H and 2-H are ascribed to different binding affinities of H?O to the Ru center of the corresponding unsaturated species, [Cp*Ru(PPh?NBn?)]+ and [Cp*Ru(PPh?NBn?)]+. In addition, studies of Cp*Ru(dmpm)H (where dmpm = bis(dimethylphosphino)methane), a control complex lacking pendent amines in its diphosphine ligand, confirms the critical roles of the pendent amines of P?N? ligands for oxidation of H?. We thank the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences, for supporting initial parts of the work. Current work is supported by the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  4. Structures of trihydroxynaphthalene reductase-fungicide complexes: implications for structure-based design and catalysis

    SciTech Connect (OSTI)

    Liao, D.-I.; Basarab, G.S.; Gatenby, A.A.; Valent, B.; Jordan, D.B.

    2010-03-08

    Trihydroxynaphthalene reductase catalyzes two intermediate steps in the fungal melanin biosynthetic pathway. The enzyme, a typical short-chain dehydrogenase, is the biochemical target of three commercial fungicides. The fungicides bind preferentially to the NADPH form of the enzyme. Three X-ray structures of the Magnaporthe grisea enzyme complexed with NADPH and two commercial and one experimental fungicide were determined at 1.7 {angstrom} (pyroquilon), 2.0 {angstrom} (2,3-dihydro-4-nitro-1H-inden-1-one, 1), and 2.1 {angstrom} (phthalide) resolutions. The chemically distinct inhibitors occupy similar space within the enzyme's active site. The three inhibitors share hydrogen bonds with the side chain hydroxyls of Ser-164 and Tyr-178 via a carbonyl oxygen (pyroquilon and 1) or via a carbonyl oxygen and a ring oxygen (phthalide). Active site residues occupy similar positions among the three structures. A buried water molecule that is hydrogen bonded to the NZ nitrogen of Lys-182 in each of the three structures likely serves to stabilize the cationic form of the residue for participation in catalysis. The pro S hydrogen of NADPH (which is transferred as a hydride to the enzyme's naphthol substrates) is directed toward the carbonyl carbon of the inhibitors that mimic an intermediate along the reaction coordinate. Modeling tetrahydroxynaphthalene and trihydroxynaphthalene in the active site shows steric and electrostatic repulsion between the extra hydroxyl oxygen of the former substrate and the sulfur atom of Met-283 (the C-terminal residue), which accounts, in part, for the 4-fold greater substrate specificity for trihydroxynaphthalene over tetrahydroxynaphthalene.

  5. Opportunities for Catalysis in The 21st Century. A report from the Basic Energy Sciences Advisory Committee

    SciTech Connect (OSTI)

    White, J. M.; Bercaw, J.

    2002-05-16

    Chemical catalysis affects our lives in myriad ways. Catalysis provides a means of changing the rates at which chemical bonds are formed and broken and of controlling the yields of chemical reactions to increase the amounts of desirable products from these reactions and reduce the amounts of undesirable ones. Thus, it lies at the heart of our quality of life: The reduced emissions of modern cars, the abundance of fresh food at our stores, and the new pharmaceuticals that improve our health are made possible by chemical reactions controlled by catalysts. Catalysis is also essential to a healthy economy: The petroleum, chemical, and pharmaceutical industries, contributors of $500 billion to the gross national product of the United States, rely on catalysts to produce everything from fuels to ''wonder drugs'' to paints to cosmetics. Today, our Nation faces a variety of challenges in creating alternative fuels, reducing harmful by-products in manufacturing, cleaning up the environment and preventing future pollution, dealing with the causes of global warming, protecting citizens from the release of toxic substances and infectious agents, and creating safe pharmaceuticals. Catalysts are needed to meet these challenges, but their complexity and diversity demand a revolution in the way catalysts are designed and used. This revolution can become reality through the application of new methods for synthesizing and characterizing molecular and material systems. Opportunities to understand and predict how catalysts work at the atomic scale and the nanoscale are now appearing, made possible by breakthroughs in the last decade in computation, measurement techniques, and imaging and by new developments in catalyst design, synthesis, and evaluation.

  6. Contact: Paul Dauenhauer (hauer@umn.edu) UD's Catalysis Center for Energy Innovation Invents New Chemical Detector

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Information Contact (If you're a human, don't change the following field) Enter your name: 8c7f598568c7f Your first name. Please enable Javascript to use this form. Your name: * Your e-mail address: * Subject: * Category: * - Please choose - STIP Website Subscribe to the OSTI.gov Newsletter Message: * Send message

    immediate release Contact: Paul Dauenhauer (hauer@umn.edu) UD's Catalysis Center for Energy Innovation Invents New Chemical Detector (NEWARK, DE) January 12, 2015 -- A team of

  7. Support for Speakers and Attendees at 2008 GRC Conference Catalysis (to be held at Colby Sawyer College, New London, New Hampshire on June 22-27, 2008)

    SciTech Connect (OSTI)

    Stuart L. Soled and Nancy Ryan Gray

    2009-01-01

    The GRC on Catalysis is one of the most prestigious catalysis conferences as it brings together leading researchers from around the world to discuss their latest, most exciting work in catalysis. The 2008 conference will continue this tradition. The conference will cover a variety of themes including new catalytic materials, theoretical and experimental approaches to improve understanding of kinetics and transport phenomena, and state of the art nanoscale characterization probes to monitor active sites. The conference promotes interactions among established researchers and young scientists. It provides a venue for students to meet, talk to and learn from some of the world leading researchers in the area. It also gives them a platform for displaying their own work during the poster sessions. The informal nature of the meeting, excellent quality of the presentations and posters, and ability to meet many outstanding colleagues makes this an excellent conference.

  8. Spin-lattice relaxation within a dimerized Ising chain in a magnetic field

    SciTech Connect (OSTI)

    Erdem, R?za E-mail: rerdem29@hotmail.com; Glp?nar, Gl; Yal?n, Orhan; Pawlak, Andrzej

    2014-07-21

    A qualitative study of the spin-lattice relaxation within a dimerized Ising chain in a magnetic field is presented. We have first determined the time dependence of the deviation of the lattice distortion parameter ?? from the equilibrium state within framework of a technique combining the statistical equilibrium theory based on the transfer matrix method and the linear theory of irreversible thermodynamics. We have shown that the time dependence of the lattice distortion parameter is characterized by a single time constant (?) which diverges around the critical point in both dimerized (??0) and uniform (?=0) phase regions. When the temperature and magnetic field are fixed to certain values, the time ? depends only on exchange coupling between the spins. It is a characteristic time associated with the long wavelength fluctuations of distortion. We have also taken into account the effects of spatial fluctuations on the relaxation time using the full Landau-Ginzburg free energy functional. We have found an explicit expression for the relaxation time as a function of temperature, coupling constant and wave vector (q) and shown that the critical mode corresponds to the case q=0. Finally, our results are found to be in good qualitative agreement with the results obtained in recent experimental study on synchrotron x-ray scattering and muon spin relaxation in diluted material Cu{sub 1?y}Mg{sub y}GeO{sub 3} where the composition y is very close to 0.0209. These results can be considered as natural extensions of some previous works on static aspects of the problem.

  9. Structure of a Longitudinal Actin Dimer Assembled by Tandem W Domains: Implications for Actin Filament Nucleation

    SciTech Connect (OSTI)

    Rebowski, Grzegorz; Namgoong, Suk; Boczkowska, Malgorzata; Leavis, Paul C.; Navaza, Jorge; Dominguez, Roberto

    2013-11-20

    Actin filament nucleators initiate polymerization in cells in a regulated manner. A common architecture among these molecules consists of tandem WASP homology 2 domains (W domains) that recruit three to four actin subunits to form a polymerization nucleus. We describe a low-resolution crystal structure of an actin dimer assembled by tandem W domains, where the first W domain is cross-linked to Cys374 of the actin subunit bound to it, whereas the last W domain is followed by the C-terminal pointed end-capping helix of thymosin {beta}4. While the arrangement of actin subunits in the dimer resembles that of a long-pitch helix of the actin filament, important differences are observed. These differences result from steric hindrance of the W domain with intersubunit contacts in the actin filament. We also determined the structure of the first W domain of Vibrio parahaemolyticus VopL cross-linked to actin Cys374 and show it to be nearly identical with non-cross-linked W-Actin structures. This result validates the use of cross-linking as a tool for the study of actin nucleation complexes, whose natural tendency to polymerize interferes with most structural methods. Combined with a biochemical analysis of nucleation, the structures may explain why nucleators based on tandem W domains with short inter-W linkers have relatively weak activity, cannot stay bound to filaments after nucleation, and are unlikely to influence filament elongation. The findings may also explain why nucleation-promoting factors of the Arp2/3 complex, which are related to tandem-W-domain nucleators, are ejected from branch junctions after nucleation. We finally show that the simple addition of the C-terminal pointed end-capping helix of thymosin {beta}4 to tandem W domains can change their activity from actin filament nucleation to monomer sequestration.

  10. A Fundamental Study on the [(?-Cl)3Mg2(THF)6]+ Dimer Electrolytes for Rechargeable Mg Batteries

    SciTech Connect (OSTI)

    Liu, Tianbiao L.; Cox, Jonathan T.; Hu, Dehong; Deng, Xuchu; Hu, Jian Z.; Hu, Mary Y.; Xiao, Jie; Shao, Yuyan; Tang, Keqi; Liu, Jun

    2015-01-01

    We present a fundamental study on [(?-Cl)3Mg2(THF)6]+dimer electrolytes using various physical methods including Subambient Pressure Ionization with Nanoelectrospray Mass spectrometry (SPIN-MS), Raman spectroscopy, 25Mg{1H} NMR, 27Al{1H} NMR and electrochemical analysis. For the first time, long time sought THF solvated [MgCl]+ species was experimentally characterized by SPIN mass spectrometry in the solution of the Mgdimer containing electrolyte, confirming the mono-Cl- abstraction reaction between MgCl2 and an Al Lewis acid. Solvated MgCl2 in the electrolyte was confirmed by Raman spectroscopy. The experimental results establish the previously proposed dimerization equilibrium of solvated [MgCl]+ and MgCl2 with [(?-Cl)3Mg2(THF)6]+. 25Mg{1H} NMR, 27Al{1H} NMR and electrochemical analysis on chloration reaction of [(?-Cl)3Mg2(THF)6]AlPh3Cl with external Cl- led to further insights on the coordination chemistry of the dimer electrolyte. Finally, a comprehensive mechanism is proposed for the reversible electrochemical Mg deposition and stripping and Mg2+ and Cl- ion transports of the Mg dimer electrolytes in rechargeable Mg batteries.

  11. Ultralow-power local laser control of the dimer density in alkali-metal vapors through photodesorption

    SciTech Connect (OSTI)

    Jha, Pankaj K.; Scully, Marlan O. [Texas A and M University, College Station, Texas 77843 (United States); Princeton University, Princeton, New Jersey 08544 (United States); Dorfman, Konstantin E. [Texas A and M University, College Station, Texas 77843 (United States); University of California, Irvine, Irvine, California 92697 (United States); Yi Zhenhuan; Yuan Luqi; Welch, George R. [Texas A and M University, College Station, Texas 77843 (United States); Sautenkov, Vladimir A. [Texas A and M University, College Station, Texas 77843 (United States); Joint Institute of High Temperature, RAS, Moscow 125412 (Russian Federation); Rostovtsev, Yuri V. [University of North Texas, Denton, Texas 76203 (United States); Zheltikov, Aleksei M. [Texas A and M University, College Station, Texas 77843 (United States); M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation)

    2012-08-27

    Ultralow-power diode-laser radiation is employed to induce photodesorption of cesium from a partially transparent thin-film cesium adsorbate on a solid surface. Using resonant Raman spectroscopy, we demonstrate that this photodesorption process enables an accurate local optical control of the density of dimer molecules in alkali-metal vapors.

  12. Recent advances in automotive catalysis for NOx emission control by small-pore microporous materials

    SciTech Connect (OSTI)

    Beale, Andrew M.; Gao, Feng; Lezcano-Gonzalez, Ines; Peden, Charles HF; Szanyi, Janos

    2015-10-05

    The ever increasing demand to develop highly fuel efficient engines coincides with the need to minimize air pollution originating from the exhaust gases of internal combustion engines. Dramatically improved fuel efficiency can be achieved at air-to-fuel ratios much higher than stoichiometric. In the presence of oxygen in large excess, however, traditional three-way catalysts are unable to reduce NOx. Among the number of lean-NOx reduction technologies, selective catalytic reduction (SCR) of NOx by NH3 over Cu- and Fe-ion exchanged zeolite catalysts has been extensively studied over the past 30+ years. Despite the significant advances in developing a viable practical zeolite-based catalyst for lean NOx reduction, the insufficient hydrothermal stabilities of the zeolite structures considered cast doubts about their real-world applicability. During the past decade a renewed interest in zeolite-based lean NOx reduction was spurred by the discovery of the very high activity of Cu-SSZ-13 (and the isostructural Cu-SAPO-34) in the NH3 SCR of NOx. These new, small-pore zeolite-based catalysts not only exhibited very high NOx conversion and N2 selectivity, but also exhibited exceptional high hydrothermal stability at high temperatures. In this review we summarize the key discoveries of the past ~5 years that lead to the introduction of these catalysts into practical application. The review first briefly discusses the structure and preparation of the CHA structure-based zeolite catalysts, and then summarizes the key learnings of the rather extensive (but not complete) characterisation work. Then we summarize the key findings of reaction kinetics studies, and provide some mechanistic details emerging from these investigations. At the end of the review we highlight some of the issues that are still need to be addressed in automotive exhaust control catalysis. Funding A.M.B. and I.L.G. would like to thank EPSRC for funding. F.G., C.H.F.P. and J.Sz. gratefully acknowledge financial support from the US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program.

  13. FY16 SBIR Phase II Release 1 Awards Announced: Includes Hydrogen Contaminants Detection, Fuel Cell and Hydrogen Catalysis, and Alkaline Membrane Electrolysis

    Broader source: Energy.gov [DOE]

    The Energy Department has announced the 2016 Small Business Innovation Research and Small Business Technology Transfer (SBIR/STTR) Phase II Release 1 awards, including three projects focused on catalysis for fuel cell and hydrogen production as well as hydrogen contaminants detection.

  14. Theoretical study of the rhodium dimer interaction with the hydrogen molecule

    SciTech Connect (OSTI)

    Castillo, S.; Cruz, A.; Cuan, A.

    1995-12-31

    The C{sub 2v} potential energy surfaces for the end-on and side-on approaches of H{sub 2} to the rhodium dimer were studied through self-consistent-field (SCF) and multiconfigurational SCF calculations, followed by extensive variational plus second-order multireference Moller-Plesset perturbational configuration interaction (CIPSI) calculations. Relativistic effective core potentials were used to replace the core electrons of the rhodium atoms. Together with the Rh{sub 2}-H{sub 2} interaction, the spectroscopic constants for the {sup 5}{summation}{sub g}{sup +}, {sup 1}{summation}{sub g}{sup +}, {sup 3}II{sub {mu}}, and {sup 1}II{sub {mu}} states of Rh{sub 2} are reported. It was found that the potential energy curves of the parallel and the perpendicular Rh{sub 2}({sup 5}{summation}{sub g}) interaction with H{sub 2} show that the rhodium dimer has the ability to capture and break the H{sub 2} molecule. The parallel interaction presents a soft potential barrier of 7.8 kcal/mol, energy necessary to surmount before the capture and breaking of the H-H bond. In the perpendicular interaction, Rh{sub 2} captures and breaks spontaneously H{sub 2}. The potential energy curve of the parallel Rh{sub 2}({sup 1}{summation}{sub g}) + H{sub 2} interaction shows that Rh{sub 2} also captures and breaks spontaneously the H{sub 2}, with a very deep well of 92.7 kcal/mol, while in the perpendicular approach, Rh{sub 2} has to surmount again a soft barrier of 5.2 kcal/mol to capture and break the H{sub 2} molecule. Finally, the energy curves of the parallel Rh{sub 2}({sup 1,3}II{sub {mu}}) + H{sub 2} interactions present capture and breaking with very small barriers. The perpendicular interactions capture and scisse the hydrogen molecule spontaneously. 35 refs., 6 tabs.

  15. Operando X-ray absorption and EPR evidence for a single electron redox process in copper catalysis

    SciTech Connect (OSTI)

    Lu, Qingquan; Zhang, Jian; Peng, Pan; Zhang, Guanghui; Huang, Zhiliang; Yi, Hong; Miller, Jeffrey T.; Lei, Aiwen

    2015-05-26

    An unprecedented single electron redox process in copper catalysis is confirmed using operando X-ray absorption and EPR spectroscopies. The oxidation state of the copper species in the interaction between Cu(II) and a sulfinic acid at room temperature, and the accurate characterization of the formed Cu(I) are clearly shown using operando X-ray absorption and EPR evidence. Further investigation of anion effects on Cu(II) discloses that bromine ions can dramatically increase the rate of the redox process. Moreover, it is proven that the sulfinic acids are converted into sulfonyl radicals, which can be trapped by 2-arylacrylic acids and various valuable β-keto sulfones are synthesized with good to excellent yields under mild conditions.

  16. Operando X-ray absorption and EPR evidence for a single electron redox process in copper catalysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Lu, Qingquan; Zhang, Jian; Peng, Pan; Zhang, Guanghui; Huang, Zhiliang; Yi, Hong; Miller, Jeffrey T.; Lei, Aiwen

    2015-05-26

    An unprecedented single electron redox process in copper catalysis is confirmed using operando X-ray absorption and EPR spectroscopies. The oxidation state of the copper species in the interaction between Cu(II) and a sulfinic acid at room temperature, and the accurate characterization of the formed Cu(I) are clearly shown using operando X-ray absorption and EPR evidence. Further investigation of anion effects on Cu(II) discloses that bromine ions can dramatically increase the rate of the redox process. Moreover, it is proven that the sulfinic acids are converted into sulfonyl radicals, which can be trapped by 2-arylacrylic acids and various valuable β-keto sulfonesmore » are synthesized with good to excellent yields under mild conditions.« less

  17. Crystal Structure of 12-Lipoxygenase Catalytic-Domain-Inhibitor Complex Identifies a Substrate-Binding Channel for Catalysis

    SciTech Connect (OSTI)

    Xu, Shu; Mueser, Timothy C.; Marnett, Lawrence J.; Funk, Jr., Max O.

    2014-10-02

    Lipoxygenases are critical enzymes in the biosynthesis of families of bioactive lipids including compounds with important roles in the initiation and resolution of inflammation and in associated diseases such as diabetes, cardiovascular disease, and cancer. Crystals diffracting to high resolution (1.9 {angstrom}) were obtained for a complex between the catalytic domain of leukocyte 12-lipoxygenase and the isoform-specific inhibitor, 4-(2-oxapentadeca-4-yne)phenylpropanoic acid (OPP). In the three-dimensional structure of the complex, the inhibitor occupied a new U-shaped channel open at one end to the surface of the protein and extending past the redox-active iron site that is essential for catalysis. In models, the channel accommodated arachidonic acid, defining the binding site for the substrate of the catalyzed reaction. There was a void adjacent to the OPP binding site connecting to the surface of the enzyme and providing a plausible access channel for the other substrate, oxygen.

  18. Methanol Synthesis over Cu/ZnO/Al2O3: The Active Site in Industrial Catalysis

    SciTech Connect (OSTI)

    Behrens, Malte

    2012-03-28

    Unlike homogeneous catalysts, heterogeneous catalysts that have been optimized through decades are typically so complex and hard to characterize that the nature of the catalytically active site is not known. This is one of the main stumbling blocks in developing rational catalyst design strategies in heterogeneous catalysis. We show here how to identify the crucial atomic structure motif for the industrial Cu/ZnO/Al{sub 2}O{sub 3} methanol synthesis catalyst. Using a combination of experimental evidence from bulk-, surface-sensitive and imaging methods collected on real high-performance catalytic systems in combination with DFT calculations. We show that the active site consists of Cu steps peppered with Zn atoms, all stabilized by a series of well defined bulk defects and surface species that need jointly to be present for the system to work.

  19. Kinetics of trans-cis isomerization in azobenzene dimers at an air-water interface

    SciTech Connect (OSTI)

    Kumar, Bharat; Suresh, K. A.

    2009-08-15

    We have studied the kinetics of trans to cis isomerization under the illumination of ultraviolet light, in the Langmuir monolayer of mesogenic azobenzene dimer, bis-[5-(4{sup '}-n-dodecyloxy benzoyloxy)-2-(4{sup ''}-methylphenylazo)phenyl] adipate, at an air-water interface. We find that the trans to cis isomerization reaction of the molecules in the monolayer shows deviation from the first-order kinetics unlike those reported on Langmuir monolayers of azobenzene molecules. We attribute the deviation from first-order kinetics to the simultaneous photoisomerization of trans isomers to form cis isomers and the reverse thermal isomerization of cis isomers to form trans isomers. Our analysis of the rate of change of mole fraction of trans isomers to form cis isomers indicates a first-order kinetics for trans to cis photoisomerization reaction and a second-order kinetics for cis to trans thermal isomerization reaction. This second-order kinetics mechanism is similar to the Lindemann-Hinshelwood mechanism for the unimolecular reactions at low concentration of reactants. The formation of the activated cis isomer by collisions is a slow process as compared to the decay of the activated cis isomer to trans isomer in the liquid expanded phase. This results in the second-order kinetics for the thermal isomerization of cis isomers.

  20. Frustrated smectic layer structures in bent-shaped dimer liquid crystals studied by x-ray microbeam diffraction

    SciTech Connect (OSTI)

    Takanishi, Yoichi; Toshimitsu, Megumi; Nakata, Michi; Takada, Naoki; Izumi, Tatsuya; Ishikawa, Ken; Takezoe, Hideo; Watanabe, Junji; Takahashi, Yumiko; Iida, Atsuo

    2006-11-15

    The layer structures in bent-shaped liquid crystal dimers mOAM5AMOm (m=6-16) have been investigated by x-ray microbeam diffraction. These liquid crystal molecules have two rodlike mesogens connected with an odd-numbered alkylene spacer and form a bent shape. In these compounds it is found that the structure changes from the single (m=6) to frustrated-layer structures (m=8, 10, and 12) and switchable frustrated-layer structures (m=14 and 16) with increasing terminal chain length. An anticlinic antiferroelectric structure is suggested in the compound with m=16, based on the different electric-field-induced reorientation behavior from those in the other dimers.

  1. Quantum spin transport through magnetic superatom dimer (Cs{sub 8}V-Cs{sub 8}V)

    SciTech Connect (OSTI)

    Zhu Lin; Khanna, Shiv N.

    2012-10-28

    Theoretical studies of the spin transport through a magnetic superatom dimer (Cs{sub 8}V)-(Cs{sub 8}V) have been carried out within a density functional theory combined with nonequilibrium Green's-function formalism. It is shown that the electronic transport is sensitive to the binding site as well as the contact distance between the dimer and the electrode, and that the conductance at zero bias exhibits an oscillatory behavior as a function of the contact distance. The conductance in ferromagnetic state shows an unusually high spin polarization that exceeds 80% at large separations. The I-V curve shows negative differential resistance for specific contact distances, whose origin lies in the shift of frontier energy levels as well as the charged state of the superatom, under external bias.

  2. Communication: Towards the binding energy and vibrational red shift of the simplest organic hydrogen bond: Harmonic constraints for methanol dimer

    SciTech Connect (OSTI)

    Heger, Matthias; Suhm, Martin A.; Mata, Ricardo A.

    2014-09-14

    The discrepancy between experimental and harmonically predicted shifts of the OH stretching fundamental of methanol upon hydrogen bonding to a second methanol unit is too large to be blamed mostly on diagonal and off-diagonal anharmonicity corrections. It is shown that a decisive contribution comes from post-MP2 electron correlation effects, which appear not to be captured by any of the popular density functionals. We also identify that the major deficiency is in the description of the donor OH bond. Together with estimates for the electronic and harmonically zero-point corrected dimer binding energies, this work provides essential constraints for a quantitative description of this simple hydrogen bond. The spectroscopic dissociation energy is predicted to be larger than 18 kJ/mol and the harmonic OH-stretching fundamental shifts by about ?121 cm{sup ?1} upon dimerization, somewhat more than in the anharmonic experiment (?111 cm{sup ?1})

  3. Preparation, catalysis, and characterization of highly dispersed molybdenum sulfide catalysts supported on a NaY zeolite

    SciTech Connect (OSTI)

    Okamoto, Yasuaki; Katsuyama, Hiromoto [Osaka Univ., Toyonaka, Osaka (Japan)] [Osaka Univ., Toyonaka, Osaka (Japan)

    1996-06-01

    The structure and dispersion of the molybdenum sulfides supported on a NaY zeolite were studied using XAFS techniques. It was found that molybdenum sulfide species prepared by sulfiding vapor deposited Mo(CO){sub 6} or by sulfiding molybdenum oxide dimer species encaged in the zeolite are highly dispersed and thermally stabilized against sintering or restructuring. These molybdenum species are formed via molybdenum sulfide dimer species as an intermediate. On the other hand, with the molybdenum sulfide catalysts prepared by an impregnation method, the sulfidation of molybdenum oxides was incomplete. The molybdenum oxide species are suggested to be mainly located in the zeolite cavities after calcination, forming isolated molybdenum oxides in tetrahedral configurations. The molybdenum sulfide species prepared from Mo(CO){sub 6} showed much higher catalytic activities for thiophene hydrodesulfurization and butadiene hydrogenation than the molybdenum sulfides prepared by the impregnation, in conformity with a higher dispersion and higher fraction of the molybdenum sulfide species. It is demonstrated that in combination with metal carbonyl techniques, zeolite supports are very suitable for the preparation of highly dispersed molybdenum sulfides at a high Mo loading.

  4. Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate

    SciTech Connect (OSTI)

    Gibson, Andrew J.; Temperton, Robert H.; Handrup, Karsten; Weston, Matthew; Mayor, Louise C.; O’Shea, James N.

    2014-06-21

    The interaction of the dye molecule N3 (cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4′-dicarbo-xylato) -ruthenium(II)) with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied using synchrotron radiation based photoelectron spectroscopy, resonant photoemission spectroscopy, and near edge X-ray absorption fine structure spectroscopy. Calibrated X-ray absorption and valence band spectra of the monolayer and multilayer coverages reveal that charge transfer is possible from the molecule to the AlNi(110) substrate via tunnelling through the ultra-thin oxide layer and into the conduction band edge of the substrate. This charge transfer mechanism is possible from the LUMO+2 and 3 in the excited state but not from the LUMO, therefore enabling core-hole clock analysis, which gives an upper limit of 6.0 ± 2.5 fs for the transfer time. This indicates that ultra-thin oxide layers are a viable material for use in dye-sensitized solar cells, which may lead to reduced recombination effects and improved efficiencies of future devices.

  5. High-Potential Electrocatalytic O2 Reduction with Nitroxyl / NOx Mediators: Implications for Fuel Cells and Aerobic Oxidation Catalysis

    SciTech Connect (OSTI)

    Gerken, James B.; Stahl, Shannon S.

    2015-07-15

    Efficient reduction of O2 to water is a central challenge in energy conversion and aerobic oxidation catalysis. In the present study, we investigate the electrochemical reduction of O2 with soluble organic nitroxyl and nitrogen oxide (NOx) mediators. When used alone, neither organic nitroxyls, such as TEMPO (2,2,6,6-tetramethyl-1-piperidinyl-N-oxyl), nor NOx species, such as sodium nitrite, are effective mediators of electrochemical O2 reduction. The combination of nitroxyl/NOx species, however, mediates sustained O2 reduction at electrochemical potentials of 0.19–0.33 V (vs. Fc/Fc+) in acetonitrile containing trifluoroacetic acid. Mechanistic analysis of the coupled redox reactions supports a process in which the nitrogen oxide catalyst drives aerobic oxidation of a nitroxyl mediator to an oxoammonium species, which then is reduced back to the nitroxyl at the cathode. The electrolysis potential is dictated by the oxoammonium/nitroxyl reduction potential. The high potentials observed with this ORR system benefit from the mechanism-based specificity for four-electron reduction of oxygen to water mediated by NOx species, together with kinetically efficient reduction of oxidized NOx species by TEMPO and other organic nitroxyls. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  6. Protonation effect on the electronic properties of 2-pyridone monomer, dimer and its water clusters: A theoretical study

    SciTech Connect (OSTI)

    Saed, Behnaz; Omidyan, Reza E-mail: reza.omidyan@u-psud.fr; Centre Laser de lUniversit Paris Sud , Bt. 106, Univ. Paris-Sud 11, 91405 Orsay Cedex

    2014-01-14

    The CC2 (second order approximate coupled cluster method) has been applied to investigate protonation effect on electronic transition energies of 2-pyridone (2PY), 2-pyridone dimer, and micro-solvated 2-pyridone (0-2 water molecules). The PE profiles of protonated 2-pyridone (2PYH{sup +}) as well as monohydrated 2PYH{sup +} at the different electronic states have been investigated. The {sup 1}??* state in protonated species (2PYH{sup +}) is a barrier free and dissociative state along the O-H stretching coordinate. In this reaction coordinate, the lowest lying {sup 1}??* predissociates the bound S{sub 1}({sup 1}??*) state, connecting the latter to a conical intersection with the S{sub 0} state. These conical intersections lead the {sup 1}??* state to proceed as predissociative state and finally direct the excited system to the ground state. Furthermore, in presence of water molecule, the {sup 1}??* state still remains dissociative but the conical intersection between {sup 1}??* and ground state disappears. In addition, according to the CC2 calculation results, it has been predicted that protonation significantly blue shifts the S{sub 1}-S{sub 0} electronic transition of monomer, dimer, and microhydrated 2-pyridone.

  7. Heat capacity of the site-diluted spin dimer system Ba₃(Mn1-xVx)₂O₈

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Samulon, E. C.; Shapiro, M. C.; Fisher, I. R.

    2011-08-05

    Heat-capacity and susceptibility measurements have been performed on the diluted spin dimer compound Ba₃(Mn1-xVx)₂O₈. The parent compound Ba₃Mn₂O₈ is a spin dimer system based on pairs of antiferromagnetically coupled S=1, 3d² Mn⁵⁺ ions such that the zero-field ground state is a product of singlets. Substitution of nonmagnetic S=0, 3d⁰ V⁵⁺ ions leads to an interacting network of unpaired Mn moments, the low-temperature properties of which are explored in the limit of small concentrations 0≤x≤0.05. The zero-field heat capacity of this diluted system reveals a progressive removal of magnetic entropy over an extended range of temperatures, with no evidence for amore » phase transition. The concentration dependence does not conform to expectations for a spin-glass state. Rather, the data suggest a low-temperature random singlet phase, reflecting the hierarchy of exchange energies found in this system.« less

  8. Benchmark Theoretical Study of the π–π Binding Energy in the Benzene Dimer

    SciTech Connect (OSTI)

    Miliordos, Evangelos; Apra, Edoardo; Xantheas, Sotiris S.

    2014-09-04

    We establish a new estimate for the interaction energy between two benzene molecules in the parallel displaced (PD) conformation by systematically converging (i) the intra- and intermolecular geometry at the minimum geometry, (ii) the expansion of the orbital basis set and (iii) the level of electron correlation. The calculations were performed at the second order Møller - Plesset perturbation (MP2) and the Coupled Cluster including Singles, Doubles and a perturbative estimate of Triples replacements [CCSD(T)] levels of electronic structure theory. At both levels of theory, by including results corrected for Basis Set Superposition Error (BSSE), we have estimated the Complete Basis Set (CBS) limit by employing the family of Dunning’s correlation consistent polarized valence basis sets. The largest MP2 calculation was performed with the cc-pV6Z basis set (2,772 basis functions), whereas the largest CCSD(T) calculation with the cc-pV5Z basis set (1,752 basis functions). The cluster geometries were optimized with basis sets up to quadruple-ζ quality, observing that both its intra- and inter-molecular parts have practically converged with the triple-ζ quality sets. The use of converged geometries was found to play an important role for obtaining accurate estimates for the CBS limits. Our results demonstrate that the binding energies with the families of the plain (cc-pVnZ) and augmented (aug-cc-pVnZ) sets converge [to within < 0.01 kcal/mol for MP2 and < 0.15 kcal/mol for CCSD(T)] to the same CBS limit. In addition, the average of the uncorrected and BSSEcorrected binding energies was found to converge to the same CBS limit must faster than either of the two constituents (uncorrected or BSSE-corrected binding energies). Due to the fact that the family of augmented basis sets (especially for the larger sets) causes serious linear dependency problems, the plain basis sets (for which no linear dependencies were found) are deemed as a more efficient and straightforward path for obtaining an accurate CBS limit. We considered extrapolations of the uncorrected (Δ𝐸) and BSSE-corrected (Δ𝐸!") binding energies, their average value (Δ𝐸!"#) as well as the average of the latter over the plain and augmented sets (Δ𝐸!"#) with the cardinal number of the basis set n. Our best estimate of the CCSD(T)/CBS limit for the π-π interaction energy in the PD benzene dimer is De = 2.65 ± 0.02 kcal/mol. The best CCSD(T)/cc-pV5Z calculated value is 2.62 kcal/mol, just 0.03 kcal/mol away from the CBS limit. For comparison, the MP2/CBS limit estimate is 5.00 ± 0.01 kcal/mol, demonstrating a 90% overbinding with respect to CCSD(T). The Spin-Component-Scaled (SCS) MP2 variant was found to closely reproduce the CCSD(T) results for each basis set, while Scaled-Opposite-Spin (SOS) yielded results that are too low when compared to CCSD(T).

  9. Superacid catalysis of light hydrocarbon conversion. DOE PETC third quarterly report, February 25, 1994--May 24, 1994

    SciTech Connect (OSTI)

    Gates, B.C.

    1995-12-31

    Environmental concerns are leading to the replacement of aromatic hydrocarbons in gasoline by high-octane-number branched paraffins and oxygenated compounds such as methyl t-butyl ether. The ether is produced from methanol and isobutylene, and the latter can be formed from n-butane by isomerization followed by dehydrogenation. Paraffin isomerization reactions are catalyzed by very strong acids such as aluminum chloride supported on alumina. The aluminum chloride-containing catalysts are corrosive, and their disposal is expensive. Alternatively, hydroisomerization is catalyzed by zeolite-supported metals at high temperatures, but high temperatures do not favor branched products at equilibrium. Thus there is a need for improved catalysts and processes for the isomerization of n-butane and other straight-chain paraffins. Consequently, researchers have sought for solid acids that are noncorrosive and active enough to catalyze isomerization of paraffins at low temperatures. For example, sulfated zirconia catalyzes isomerization of n-butane at temperatures as low as 25{degrees}C. The addition of iron and manganese promoters has been reported to increase the activity of sulfated zirconia for n-butane isomerization by three orders of magnitude. Although the high activity of this catalyst is now established, the reaction network is not known, and the mechanism has not been investigated. The goal of this work is to investigate low-temperature reactions of light paraffins catalyzed by solid superacids of the sulfated zirconia type. The present report is concerned with catalysis of n-butane conversion catalyzed by the Fe- and Mn- promoted sulfated zirconia described in the previous report in this series.

  10. Bioinspired design of redox-active ligands for multielectron catalysis: Effects of positioning pyrazine reservoirs on cobalt for electro- and photocatalytic generation of hydrogen from water

    SciTech Connect (OSTI)

    Jurss, Jonah W.; Khnayzer, Rony S.; Panetier, Julien A.; El Roz, Karim A.; Nichols, Eva M.; Head-Gordon, Martin; Long, Jeffrey R.; Castellano, Felix N.; Chang, Christopher J.

    2015-06-09

    Mononuclear metalloenzymes in nature can function in cooperation with precisely positioned redox-active organic cofactors in order to carry out multielectron catalysis. Inspired by the finely tuned redox management of these bioinorganic systems, we present the design, synthesis, and experimental and theoretical characterization of a homologous series of cobalt complexes bearing redox-active pyrazines. These donor moieties are locked into key positions within a pentadentate ligand scaffold in order to evaluate the effects of positioning redox non-innocent ligands on hydrogen evolution catalysis. Both metal- and ligand-centered redox features are observed in organic as well as aqueous solutions over a range of pH values, and comparison with analogs bearing redox-inactive zinc(II) allows for assignments of ligand-based redox events. Varying the geometric placement of redox non-innocent pyrazine donors on isostructural pentadentate ligand platforms results in marked effects on observed cobalt-catalyzed proton reduction activity. Electrocatalytic hydrogen evolution from weak acids in acetonitrile solution, under diffusion-limited conditions, reveals that the pyrazine donor of axial isomer 1-Co behaves as an unproductive electron sink, resulting in high overpotentials for proton reduction, whereas the equatorial pyrazine isomer complex 2-Co is significantly more active for hydrogen generation at lower voltages. Addition of a second equatorial pyrazine in complex 3-Co further minimizes overpotentials required for catalysis. The equatorial derivative 2-Co is also superior to its axial 1-Co congener for electrocatalytic and visible-light photocatalytic hydrogen generation in biologically relevant, neutral pH aqueous media. Density functional theory calculations (B3LYP-D2) indicate that the first reduction of catalyst isomers 1-Co, 2-Co, and 3-Co is largely metal-centered while the second reduction occurs at pyrazine. Taken together, the data establish that proper positioning of non-innocent pyrazine ligands on a single cobalt center is indeed critical for promoting efficient hydrogen catalysis in aqueous media, akin to optimally positioned redox-active cofactors in metalloenzymes. In a broader sense, these findings highlight the significance of electronic structure considerations in the design of effective electron–hole reservoirs for multielectron transformations.

  11. Bioinspired design of redox-active ligands for multielectron catalysis: Effects of positioning pyrazine reservoirs on cobalt for electro- and photocatalytic generation of hydrogen from water

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Jurss, Jonah W.; Khnayzer, Rony S.; Panetier, Julien A.; El Roz, Karim A.; Nichols, Eva M.; Head-Gordon, Martin; Long, Jeffrey R.; Castellano, Felix N.; Chang, Christopher J.

    2015-06-09

    Mononuclear metalloenzymes in nature can function in cooperation with precisely positioned redox-active organic cofactors in order to carry out multielectron catalysis. Inspired by the finely tuned redox management of these bioinorganic systems, we present the design, synthesis, and experimental and theoretical characterization of a homologous series of cobalt complexes bearing redox-active pyrazines. These donor moieties are locked into key positions within a pentadentate ligand scaffold in order to evaluate the effects of positioning redox non-innocent ligands on hydrogen evolution catalysis. Both metal- and ligand-centered redox features are observed in organic as well as aqueous solutions over a range of pHmore » values, and comparison with analogs bearing redox-inactive zinc(II) allows for assignments of ligand-based redox events. Varying the geometric placement of redox non-innocent pyrazine donors on isostructural pentadentate ligand platforms results in marked effects on observed cobalt-catalyzed proton reduction activity. Electrocatalytic hydrogen evolution from weak acids in acetonitrile solution, under diffusion-limited conditions, reveals that the pyrazine donor of axial isomer 1-Co behaves as an unproductive electron sink, resulting in high overpotentials for proton reduction, whereas the equatorial pyrazine isomer complex 2-Co is significantly more active for hydrogen generation at lower voltages. Addition of a second equatorial pyrazine in complex 3-Co further minimizes overpotentials required for catalysis. The equatorial derivative 2-Co is also superior to its axial 1-Co congener for electrocatalytic and visible-light photocatalytic hydrogen generation in biologically relevant, neutral pH aqueous media. Density functional theory calculations (B3LYP-D2) indicate that the first reduction of catalyst isomers 1-Co, 2-Co, and 3-Co is largely metal-centered while the second reduction occurs at pyrazine. Taken together, the data establish that proper positioning of non-innocent pyrazine ligands on a single cobalt center is indeed critical for promoting efficient hydrogen catalysis in aqueous media, akin to optimally positioned redox-active cofactors in metalloenzymes. In a broader sense, these findings highlight the significance of electronic structure considerations in the design of effective electron–hole reservoirs for multielectron transformations.« less

  12. Laser induced fluorescence spectroscopy of the Ca dimer deposited on helium and mixed helium/xenon clusters

    SciTech Connect (OSTI)

    Gaveau, Marc-Andr; Pothier, Christophe; Briant, Marc; Mestdagh, Jean-Michel

    2014-12-09

    We study how the laser induced fluorescence spectroscopy of the calcium dimer deposited on pure helium clusters is modified by the addition of xenon atoms. In the wavelength range between 365 and 385 nm, the Ca dimer is excited from its ground state up to two excited electronic states leading to its photodissociation in Ca({sup 1}P)+Ca({sup 1}S): this process is monitored by recording the Ca({sup 1}P) fluorescence at 422.7nm. One of these electronic states of Ca{sub 2} is a diexcited one correlating to the Ca(4s4p{sup 3}P(+Ca(4s3d{sup 3}D), the other one is a repulsive state correlating to the Ca(4s4p1P)+Ca(4s21S) asymptote, accounting for the dissociation of Ca{sub 2} and the observation of the subsequent Ca({sup 1}P) emission. On pure helium clusters, the fluorescence exhibits the calcium atomic resonance line Ca({sup 1}S?{sup 1}P) at 422.7 nm (23652 cm{sup ?1}) assigned to ejected calcium, and a narrow red sided band corresponding to calcium that remains solvated on the helium cluster. When adding xenon atoms to the helium clusters, the intensity of these two features decreases and a new spectral band appears on the red side of calcium resonance line; the intensity and the red shift of this component increase along with the xenon quantity deposited on the helium cluster: it is assigned to the emission of Ca({sup 1}P) associated with the small xenon aggregate embedded inside the helium cluster.

  13. Photochemistry of the water dimer: Time-dependent quantum wave-packet description of the dynamics at the S{sub 1}-S{sub 0} conical intersection

    SciTech Connect (OSTI)

    Chmura, Bartosz; Rode, Michal F.; Sobolewski, Andrzej L.; Lan Zhenggang

    2009-10-07

    The photoinduced electron-driven proton-transfer dynamics of the water-dimer system has been investigated by time-dependent quantum wave-packet calculations. The main nuclear degrees of freedom driving the system from the Frank-Condon region to the S{sub 0}-S{sub 1} conical intersection are the distance between the oxygen atoms and the displacement of the hydrogen atom from the oxygen-oxygen bond center. Two important coupling modes have been investigated: Rotation of the H-donating water dangling proton and asymmetric stretching of the H-accepting water dangling protons'O{sub a}H bonds. Potential energy surfaces of the ground and lowest excited electronic states have been constructed on the basis of ab initio calculations. The time-dependent quantum wave-packet propagation has been employed within the (2 + 1)-dimensional systems for the description of the nonadiabatic dynamics of water dimer. The effects of the initial vibrational state of the system on the electronic population transfer and dissociation dynamics are presented. To approximate the photochemical behavior of water dimer in bulk water, we add a boundary condition into the (2 + 1)-dimensional systems to simulate the existence of water bulk. The results provide insight into the mechanisms of excited state deactivation of the water-dimer system in gas phase and in bulk water through the electron-driven proton-transfer process.

  14. DESIGN, SYNTHESIS, AND MECHANISTIC EVALUATION OF IRON-BASED CATALYSIS FOR SYNTHESIS GAS CONVERSION TO FUELS AND CHEMICALS

    SciTech Connect (OSTI)

    Akio Ishikawa; Manuel Ojeda; Enrique Iglesia

    2005-03-31

    This project explores the extension of previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have previously shown unprecedented Fischer-Tropsch synthesis rate, selectivity with synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic performance previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During this third reporting period, we have prepared a large number of Fe-based catalyst compositions using precipitation and impregnations methods with both supercritical and subcritical drying and with the systematic use of surface active agents to prevent pore collapse during drying steps required in synthetic protocols. These samples were characterized during this period using X-ray diffraction, surface area, and temperature-programmed reduction measurements. These studies have shown that these synthesis methods lead to even higher surface areas than in our previous studies and confirm the crystalline structures of these materials and their reactivity in both oxide-carbide interconversions and in Fischer-Tropsch synthesis catalysis. Fischer-Tropsch synthesis reaction rates and selectivities with low H{sub 2}/CO ratio feeds (H{sub 2}/CO = 1) were the highest reported in the literature at the low-temperature and relatively low pressure in our measurements. Current studies are exploring the optimization of the sequence of impregnation of Cu, K, and Ru promoters, of the activation and reaction conditions, and of the co-addition of light hydrocarbons to increase diffusion rates of primary olefin products so as to increase the selectivity to unsaturated products. Finally, we are also addressing the detailed kinetic response of optimized catalysts to reaction conditions (temperature, partial pressures of H{sub 2}, CO, H{sub 2}O, CO{sub 2}, olefins) in an effort to further increase rates and olefin and C{sub 5+} selectivities.

  15. Superacid catalysis of light hydrocarbon conversion. DOE PETC seventh quarterly progress report, April 1, 1995--July 31, 1995

    SciTech Connect (OSTI)

    Gates, B.C.

    1996-02-01

    Iron- and manganese-promoted sulfated zirconia is a catalyst for the conversion of propane, but the rate of conversion of propane is much less than the rate of conversion of butane. Whereas this catalyst appears to be a good candidate for practical, industrial conversion of butane, it appears to lack sufficient activity for practical conversion of propane. The propane conversion data reported here provide excellent insights into the chemistry of the catalytic conversion. Solid and catalysts, namely, sulfated zirconia, iron- and manganese-promoted sulfated zirconia, and USY zeolite, were tested for conversion of propane at 1 atm, 200-450{degrees}C, and propane partial pressures in the range of 0.01-0.05 atm. Both promoted and unpromoted sulfated zirconia were found to be active for conversion of propane into butanes, pentanes, methane, ethane, ethylene, and propylene in the temperature range of 200-350{degrees}C, but catalyst deactivation was rapid. At the higher temperatures, only cracking and dehydrogenation products were observed. In contrast to the zirconia-supported catalysts, USY zeolite was observed to convert propane (into propylene, methane, and ethylene) only at temperatures {ge}400{degrees}C. The initial (5 min on stream) rates of propane conversion in the presence of iron- and manganese-promoted sulfated zirconia, sulfated zirconia, and USY zeolite at 450{degrees}C and 0.01 atm propane partial pressure were 3.3 x 10{sup -8}, 0.3 x 10{sup -8}, and 0.06 x 10{sup -8} mol/(s{center_dot}g), respectively. The product distributions in the temperature range 200-450{degrees}C are those of acid-base catalysis, being similar to what has been observed in superacid solution chemistry at temperatures <0{degrees}C. If propane conversion at 450{degrees}C can be considered as a probe of acid strength of the catalyst, the activity comparison suggests that the promoted sulfated zirconia is a stronger acid than sulfated zirconia, which is a stronger acid than USY zeolite.

  16. 2012 Catalysis Lectures

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    his sabbatical period at Stanford University and SLAC. (1) "Characterization of Heterogeneous Catalysts: Possibilities and Limitations of In-situ Spectroscopy" (Part I) Monday,...

  17. Design, Synthesis and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect (OSTI)

    Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

    2007-03-31

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rates and selectivities for synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch Synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based materials with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During the fifth and sixth reporting period, we studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influenced the performance of these materials in the Fischer-Tropsch synthesis. We also continued our studies of the kinetic behavior of these materials during the sixth reporting period. Specifically, the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch Synthesis reactions led us to propose a new sequence of elementary steps on Fe and Co Fischer-Tropsch catalysts. Finally, we also started a study of the use of colloidal precipitation methods for the synthesis small Co clusters using recently developed methods to explore possible further improvements in FTS rates and selectivities. We found that colloidal synthesis makes possible the preparation of small cobalt particles, although large amount of cobalt silicate species, which are difficult to reduce, were formed. During this seventh reporting period, we have explored several methods to modify the silanol groups on SiO{sub 2} by using either a homogeneous deposition-precipitation method or surface titration of Si-OH on SiO{sub 2} with zirconium (IV) ethoxide to prevent the formation of unreducible and unreactive CoO{sub x} species during synthesis and FTS catalysis. We have synthesized monometallic Co/ZrO{sub 2}/SiO{sub 2} catalysts with different Co loadings (11-20 wt%) by incipient wetness impregnation methods and characterized the prepared Co supported catalysts by H{sub 2} temperature-programmed reduction (H{sub 2}-TPR) and H{sub 2}-chemisorption. We have measured the catalytic performance in FTS reactions and shown that although the hydroxyl groups on the SiO{sub 2} surface are difficult to be fully titrated by ZrO{sub 2}, modification of ZrO{sub 2} on SiO{sub 2} surface can improve the Co clusters dispersion and lead to a larger number of exposed Co surface atoms after reduction and during FTS reactions. During this seventh reporting period, we have also advanced our development of the reaction mechanism proposed in the previous reporting period. Specifically, we have shown that our novel proposal for the pathways involved in CO activation on Fe and Co catalysts is consistent with state-of-the-art theoretical calculations carried out in collaboration with Prof. Manos Mavrikakis (University of Wisconsin-Madison). Finally, we have also worked on the preparation of several manuscripts describing our findings about the preparation, activation and mechanism of the FTS with Fe-based catalysts and we have started redacting the final report for this project.

  18. Theoretical Studies in Heterogenous Catalysis: Towards a Rational Design of Novel Catalysts for Hydrodesulfurization and Hydrogen Production

    SciTech Connect (OSTI)

    Rodriguez,J.A.; Liu, P.

    2008-10-01

    Traditionally, knowledge in heterogeneous catalysis has come through empirical research. Nowadays, there is a clear interest to change this since millions of dollars in products are generated every year in the chemical and petrochemical industries through catalytic processes. To obtain a fundamental knowledge of the factors that determine the activity of heterogeneous catalysts is a challenge for modern science since many of these systems are very complex in nature. In principle, when a molecule adsorbs on the surface of a heterogeneous catalyst, it can interact with a large number of bonding sites. It is known that the chemical properties of these bonding sites depend strongly on the chemical environment around them. Thus, there can be big variations in chemical reactivity when going from one region to another in the surface of a heterogeneous catalyst. A main objective is to understand how the structural and electronic properties of a surface affect the energetics for adsorption processes and the paths for dissociation and chemical reactions. In recent years, advances in instrumentation and experimental procedures have allowed a large series of detailed works on the surface chemistry of heterogeneous catalysts. In many cases, these experimental studies have shown interesting and unique phenomena. Theory is needed to unravel the basic interactions behind these phenomena and to provide a general framework for the interpretation of experimental results. Ideally, theoretical calculations based on density-functional theory have evolved to the point that one should be able to predict patterns in the activity of catalytic surfaces. As in the case of experimental techniques, no single theoretical approach is able to address the large diversity of phenomena occurring on a catalyst. Catalytic surfaces are usually modeled using either a finite cluster or a two-dimensionally periodic slab. Many articles have been published comparing the results of these two approaches. An important advantage of the cluster approach is that one can use the whole spectrum of quantum-chemical methods developed for small molecules with relatively minor modifications. On the other hand, the numerical effort involved in cluster calculations increases rather quickly with the size of the cluster. This problem does not exist when using slab models. Due to the explicit incorporation of the periodicity of the crystal lattice through the Bloch theorem, the actual dimension of a slab calculation depends only on the size of the unit cell. In practical terms, the slab approach is mainly useful for investigating the behavior of adsorbates at medium and high coverages. Very large unit cells are required at the limit of low to zero coverage, or when examining the properties and chemical behavior of isolated defect sites in a surface. In these cases, from a computational viewpoint, the cluster approach can be much more cost effective than the slab approach. Slab and cluster calculations can be performed at different levels of sophistication: semi-empirical methods, simple ab initio Hartree-Fock, ab initio post-Hartree-Fock (CI, MP2, etc), and density functional theory. Density-functional (DF) based calculations frequently give adsorption geometries with a high degree of accuracy and predict reliable trends for the energetics of adsorption reactions. This article provides a review of recent theoretical studies that deal with the behavior of novel catalysts used for hydrodesulfurization (HDS) reactions and the production of hydrogen (i.e. catalytic processes employed in the generation of clean fuels). These studies involve a strong coupling of theory and experiment. A significant fraction of the review is focused on the importance of size-effects and correlations between the electronic and chemical properties of catalytic materials. The article begins with a discussion of results for the desulfurization of thiophene on metal carbides and phosphides, systems which have the potential to become the next generation of industrial HDS catalysts. Then, systematic studies con

  19. A Hard X-ray Study of a Manganese-Terpyridine Dimer Catalyst in a Chromium-based Metal Organic Framework - Oral Presentation

    SciTech Connect (OSTI)

    Ramsey, Alexandra

    2015-08-25

    Cleaner forms of energy are needed, and H2 produced from water spliFng is a possible source. However, a robust catalyst is necessary to carry out the water oxidaKon reacKon. Plants uKlize Photosystem II to catalyze water oxidaKon as a part of photosynthesis, and many syntheKc water oxidaKon catalysts use Photosystem II as a model. In this study, the catalyst of interest was [(terpy)Mn(?-O)2Mn(terpy)]3+ (MnTD), which was synthesized in a chromium-based Metal Organic Framework (MOF) to avoid degradaKon of MnTD molecules. Hard X-ray powder diffracKon was the primary method of analysis. The diffracKon data was used to detect the presence of MOF in samples at different catalyKc stages, and laFce parameters were assigned to the samples containing MOF. Fourier maps were constructed to determine the contents of the MOF as preliminary studies suggested that MnTD may not be present. Results showed that MOF is present before catalysis occurs, but disappears in the iniKal stages of catalysis. Changes in the MOFs laFce parameters suggest aWracKve interacKons between the MOF and catalyst; these interacKons may lead to the observed MOF degradaKon. Fourier maps also reveal limited, if any, amounts of MnTD in the system. Molecular manganese oxide may be the source of the high rate of water oxidaKon catalysis in the studied system.

  20. Gas phase measurements of mono-fluoro-benzoic acids and the dimer of 3-fluoro-benzoic acid

    SciTech Connect (OSTI)

    Daly, Adam M.; Carey, Spencer J.; Pejlovas, Aaron M.; Li, Kexin; Kukolich, Stephen G.; Kang, Lu

    2015-04-14

    The microwave spectrum of the mono-fluoro-benzoic acids, 2-fluoro-, 3-fluoro-, and 4-fluoro-benzoic acid have been measured in the frequency range of 4-14 GHz using a pulsed beam Fourier transform microwave spectrometer. Measured rotational transition lines were assigned and fit using a rigid rotor Hamiltonian. Assignments were made for 3 conformers of 2-fluorobenzoic acid, 2 conformers of 3-fluorobenzoic acid, and 1 conformer of 4-fluorobenzoic acid. Additionally, the gas phase homodimer of 3-fluorobenzoic acid was detected, and the spectra showed evidence of proton tunneling. Experimental rotational constants are A(0{sup +}) = 1151.8(5), B(0{sup +}) = 100.3(5), C(0{sup +}) = 87.64(3) MHz and A(0{sup ?}) = 1152.2(5), B(0{sup ?}) = 100.7(5), C(0{sup ?}) = 88.85(3) MHz for the two ground vibrational states split by the proton tunneling motion. The tunneling splitting (?E) is approximately 560 MHz. This homodimer appears to be the largest carboxylic acid dimer observed with F-T microwave spectroscopy.

  1. Two Dihydroxo-Bridged Plutonium(IV) Nitrate Dimers and Their Relevance to Trends in Tetravalent Ion Hydrolysis and Condensation

    SciTech Connect (OSTI)

    Knope, Karah E.; Skanthakumar, S.; Soderholm, L.

    2015-11-02

    We report the room temperature synthesis and structural characterization of a μ2-hydroxobridged PuIV dimer obtained from an acidic, nitric acid solution. The discrete Pu2(OH)2(NO3)6(H2O)4 moiety crystallized with two distinct crystal structures, (1) [Pu2(OH)2(NO3)6(H2O)4]2·11H2O and (2) Pu2(OH)2(NO3)6(H2O)4·2H2O, which differ primarily in the number of incorporated water molecules. High-energy X-ray scattering (HEXS) data obtained from the mother liquor showed evidence of a correlation at 3.7(10) Å but only after concentration of the stock solution. This distance is consistent with the dihydroxo-bridged distance of 3.799(1) Å seen in the solid-state structure as well as with the known Pu-Pu distance in PuO2. The structural characterization of a dihydroxo-bridged Pu moiety is discussed in terms of its relevance to the underlying mechanisms of tetravalent-metal-ion condensation

  2. Combining X-ray Absorption and X-ray Diffraction Techniques for in Situ Studies of Chemical Transformations in Heterogeneous Catalysis: Advantages and Limitations

    SciTech Connect (OSTI)

    Frenkel, A.I.; Hanson, J.; Wang, Q.; Marinkovic, N.; Chen, J.G.; Barrio, L.; Si, R.; Lopez Camara, A.; Estrella, A.M.; Rodriguez, J.A.

    2011-08-05

    Recent advances in catalysis instrumentations include synchrotron-based facilities where time-resolved X-ray scattering and absorption techniques are combined in the same in situ or operando experiment to study catalysts at work. To evaluate the advances and limitations of this method, we performed a series of experiments at the new XAFS/XRD instrument in the National Synchrotron Light Source. Nearly simultaneous X-ray diffraction (XRD) and X-ray absorption fine-structure (XAFS) measurements of structure and kinetics of several catalysts under reducing or oxidizing conditions have been performed and carefully analyzed. For CuFe{sub 2}O{sub 4} under reducing conditions, the combined use of the two techniques allowed us to obtain accurate data on kinetics of nucleation and growth of metallic Cu. For the inverse catalyst CuO/CeO{sub 2} that underwent isothermal reduction (with CO) and oxidation (with O{sub 2}), the XAFS data measured in the same experiment with XRD revealed strongly disordered Cu species that went undetected by diffraction. These and other examples emphasize the unique sensitivity of these two complementary methods to follow catalytic processes in the broad ranges of length and time scales.

  3. Combining X-ray Absorption and X-ray Diffraction Techniques for in Situ Studies of Chemical Transformations in Heterogeneous Catalysis:Advantages and Limitations

    SciTech Connect (OSTI)

    A Frenkel; Q Wang; N Marinkovic; J Chen; L Barrio; R Si; A Lopez Camara; A Estella; J Rodriquez; J Hanson

    2011-12-31

    Recent advances in catalysis instrumentations include synchrotron-based facilities where time-resolved X-ray scattering and absorption techniques are combined in the same in situ or operando experiment to study catalysts at work. To evaluate the advances and limitations of this method, we performed a series of experiments at the new XAFS/XRD instrument in the National Synchrotron Light Source. Nearly simultaneous X-ray diffraction (XRD) and X-ray absorption fine-structure (XAFS) measurements of structure and kinetics of several catalysts under reducing or oxidizing conditions have been performed and carefully analyzed. For CuFe{sub 2}O{sub 4} under reducing conditions, the combined use of the two techniques allowed us to obtain accurate data on kinetics of nucleation and growth of metallic Cu. For the inverse catalyst CuO/CeO{sub 2} that underwent isothermal reduction (with CO) and oxidation (with O{sub 2}), the XAFS data measured in the same experiment with XRD revealed strongly disordered Cu species that went undetected by diffraction. These and other examples emphasize the unique sensitivity of these two complementary methods to follow catalytic processes in the broad ranges of length and time scales.

  4. Heat capacity of the site-diluted spin dimer system Ba?(Mn1-xVx)?O?

    SciTech Connect (OSTI)

    Samulon, E. C.; Shapiro, M. C.; Fisher, I. R.

    2011-08-05

    Heat-capacity and susceptibility measurements have been performed on the diluted spin dimer compound Ba?(Mn1-xVx)?O?. The parent compound Ba?Mn?O? is a spin dimer system based on pairs of antiferromagnetically coupled S=1, 3d Mn?? ions such that the zero-field ground state is a product of singlets. Substitution of nonmagnetic S=0, 3d? V?? ions leads to an interacting network of unpaired Mn moments, the low-temperature properties of which are explored in the limit of small concentrations 0?x?0.05. The zero-field heat capacity of this diluted system reveals a progressive removal of magnetic entropy over an extended range of temperatures, with no evidence for a phase transition. The concentration dependence does not conform to expectations for a spin-glass state. Rather, the data suggest a low-temperature random singlet phase, reflecting the hierarchy of exchange energies found in this system.

  5. Magnons and continua in a magnetized and dimerized spin - 12 chain

    SciTech Connect (OSTI)

    Stone, M. B.; Chen, Y.; Reich, D. H.; Broholm, C.; Xu, G.; Copley, J. R. D.; Cook, J. C.

    2014-09-29

    We examine the magnetic field dependent excitations of the dimerized spin -1/2 chain, copper nitrate, with antiferromagnetic intra-dimer exchange $J_1=0.44$ (1) meV and exchange alternation $\\alpha=J_2/J_1=0.26$ (2). Magnetic excitations in three distinct regimes of magnetization are probed through inelastic neutron scattering at low temperatures. At low and high fields there are three and two long-lived magnon-like modes, respectively. The number of modes and the anti-phase relationship between the wave-vector dependent energy and intensity of magnon scattering reflect the distinct ground states: A singlet ground state at low fields $\\mu_0H < \\mu_0H_{c1} = 2.8$ T and an $S_z=1/2$ product state at high fields $\\mu_0H > \\mu_0H_{c2} = 4.2$ T. Lastly, in the intermediate field regime, a continuum of scattering for $\\hbar\\omega\\approx J_1$ is indicative of a strongly correlated gapless quantum state without coherent magnons.

  6. Analysis of the S{sub 2}←S{sub 0} vibronic spectrum of the ortho-cyanophenol dimer using a multimode vibronic coupling approach

    SciTech Connect (OSTI)

    Kopec, Sabine; Köppel, Horst; Ottiger, Philipp; Leutwyler, Samuel

    2015-02-28

    The S{sub 2}←S{sub 0} vibronic spectrum of the ortho-cyanophenol dimer (oCP){sub 2} is analyzed in a joint experimental and theoretical investigation. Vibronic excitation energies up to 750 cm{sup −1} are covered, which extends our previous analysis of the quenching of the excitonic splitting in this and related species [Kopec et al., J. Chem. Phys. 137, 184312 (2012)]. As we demonstrate, this necessitates an extension of the coupling model. Accordingly, we compute the potential energy surfaces of the ortho-cyanophenol dimer (oCP){sub 2} along all relevant normal modes using the approximate second-order coupled cluster method RI-CC2 and extract the corresponding coupling constants using the linear and quadratic vibronic coupling scheme. These serve as the basis to calculate the vibronic spectrum. The theoretical results are found to be in good agreement with the experimental highly resolved resonant two-photon ionization spectrum. This allows to interpret key features of the excitonic and vibronic interactions in terms of nodal patterns of the underlying vibronic wave functions.

  7. The effect of hydrogen bonding on torsional dynamics: A combined far-infrared jet and matrix isolation study of methanol dimer

    SciTech Connect (OSTI)

    Kollipost, F.; Heger, M.; Suhm, M. A.; Andersen, J.; Mahler, D. W.; Wugt Larsen, R.; Heimdal, J.

    2014-11-07

    The effect of strong intermolecular hydrogen bonding on torsional degrees of freedom is investigated by far-infrared absorption spectroscopy for different methanol dimer isotopologues isolated in supersonic jet expansions or embedded in inert neon matrices at low temperatures. For the vacuum-isolated and Ne-embedded methanol dimer, the hydrogen bond OH librational mode of the donor subunit is finally observed at ?560 cm{sup ?1}, blue-shifted by more than 300 cm{sup ?1} relative to the OH torsional fundamental of the free methanol monomer. The OH torsional mode of the acceptor embedded in neon is observed at ?286 cm{sup ?1}. The experimental findings are held against harmonic predictions from local coupled-cluster methods with single and double excitations and a perturbative treatment of triple excitations [LCCSD(T)] and anharmonic. VPT2 corrections at canonical MP2 and density functional theory (DFT) levels in order to quantify the contribution of vibrational anharmonicity for this important class of intermolecular hydrogen bond vibrational motion.

  8. Visible-Light Photoredox Catalysis: Selective Reduction of Carbon Dioxide to Carbon Monoxide by a Nickel N-Heterocyclic Carbene-Isoquinoline Complex

    SciTech Connect (OSTI)

    Thoi, VanSara; Kornienko, Nick; Margarit, C; Yang, Peidong; Chang, Christopher

    2013-06-07

    The solar-driven reduction of carbon dioxide to value-added chemical fuels is a longstanding challenge in the fields of catalysis, energy science, and green chemistry. In order to develop effective CO2 fixation, several key considerations must be balanced, including (1) catalyst selectivity for promoting CO2 reduction over competing hydrogen generation from proton reduction, (2) visible-light harvesting that matches the solar spectrum, and (3) the use of cheap and earth-abundant catalytic components. In this report, we present the synthesis and characterization of a new family of earth-abundant nickel complexes supported by N-heterocyclic carbene amine ligands that exhibit high selectivity and activity for the electrocatalytic and photocatalytic conversion of CO2 to CO. Systematic changes in the carbene and amine donors of the ligand have been surveyed, and [Ni(Prbimiq1)]2+ (1c, where Prbimiq1 = bis(3-(imidazolyl)isoquinolinyl)propane) emerges as a catalyst for electrochemical reduction of CO2 with the lowest cathodic onset potential (Ecat = 1.2 V vs SCE). Using this earth-abundant catalyst with Ir(ppy)3 (where ppy = 2-phenylpyridine) and an electron donor, we have developed a visible-light photoredox system for the catalytic conversion of CO2 to CO that proceeds with high selectivity and activity and achieves turnover numbers and turnover frequencies reaching 98,000 and 3.9 s1, respectively. Further studies reveal that the overall efficiency of this solar-to-fuel cycle may be limited by the formation of the active Ni catalyst and/or the chemical reduction of CO2 to CO at the reduced nickel center and provide a starting point for improved photoredox systems for sustainable carbon-neutral energy conversion.

  9. Global Structure of a Three-Way Junction in a Phi29 Packaging RNA Dimer Determined Using Site-Directed Spin Labeling

    SciTech Connect (OSTI)

    Zhang, Xiaojun; Tung, Chang-Shung; Sowa, Glenna; Hatmal, Ma'mon M.; Haworth, Ian S.; Qin, Peter Z.

    2012-02-08

    The condensation of bacteriophage phi29 genomic DNA into its preformed procapsid requires the DNA packaging motor, which is the strongest known biological motor. The packaging motor is an intricate ring-shaped protein/RNA complex, and its function requires an RNA component called packaging RNA (pRNA). Current structural information on pRNA is limited, which hinders studies of motor function. Here, we used site-directed spin labeling to map the conformation of a pRNA three-way junction that bridges binding sites for the motor ATPase and the procapsid. The studies were carried out on a pRNA dimer, which is the simplest ring-shaped pRNA complex and serves as a functional intermediate during motor assembly. Using a nucleotide-independent labeling scheme, stable nitroxide radicals were attached to eight specific pRNA sites without perturbing RNA folding and dimer formation, and a total of 17 internitroxide distances spanning the three-way junction were measured using Double Electron-Electron Resonance spectroscopy. The measured distances, together with steric chemical constraints, were used to select 3662 viable three-way junction models from a pool of 65 billion. The results reveal a similar conformation among the viable models, with two of the helices (HT and HL) adopting an acute bend. This is in contrast to a recently reported pRNA tetramer crystal structure, in which HT and HL stack onto each other linearly. The studies establish a new method for mapping global structures of complex RNA molecules, and provide information on pRNA conformation that aids investigations of phi29 packaging motor and developments of pRNA-based nanomedicine and nanomaterial.

  10. Characterization of fundamental catalytic properties of MoS2/WS2 nanotubes and nanoclusters for desulfurization catalysis - a surface temperature study

    SciTech Connect (OSTI)

    U. Burghaus

    2012-07-05

    The prior project consisted of two main project lines. First, characterization of novel nanomaterials for hydrodesulfurization (HDS) applications. Second, studying more traditional model systems for HDS such as vapor-deposited silica-supported Mo and MoSx clusters. In the first subproject, we studied WS2 and MoS2 fullerene-like nanoparticles as well as WS2 nanotubes. Thiophene (C4H4S) was used as the probe molecule. Interestingly, metallic and sulfur-like adsorption sites could be identified on the silica-supported fullerene-particles system. Similar structures are seen for the traditional system (vapor-deposited clusters). Thus, this may be a kinetics fingerprint feature of modern HDS model systems. In addition, kinetics data allowed characterization of the different adsorption sites for thiophene on and inside WS2 nanotube bundles. The latter is a unique feature of nanotubes that has not been reported before for any inorganic nanotube system; however, examples are known for carbon nanotubes, including prior work of the PI. Although HDS has been studied for decades, utilizing nanotubes as nanosized HDS reactors has never been tried before, as far as we know. This is of interest from a fundamental perspective. Unfortunately, the HDS activity of the nanocatalysts at ultra-high vacuum (UHV) conditions was close to the detection limit of our techniques. Therefore, we propose to run experiments at ambient pressure on related nanopowder samples as part of the renewal application utilizing a now-available GC (gas chromatograph) setup. In addition, Ni and Co doped nanocatalyts are proposed for study. These dopants will boost the catalytic activity. In the second subproject of the prior grant, we studied HDS-related chemistry on more traditional supported cluster catalysts. Mo clusters supported by physical vapor deposition (PVD) on silica have been characterized. Two reaction pathways are evident when adsorbing thiophene on Mo and MoSx clusters: molecular adsorption and dissociation. PVD Mo clusters turned out to be very reactive toward thiophene bond activation. Sulfur and carbon residuals form, which poison the catalyst and sulfide the Mo clusters. Sulfided silica-supported MoSx samples are not reactive toward thiophene bond activation. In addition to S and C deposits, H2, H2S, and small organic molecules were detected in the gas phase. Catalyst reactivation procedures, including O2 and atomic hydrogen treatments, have been tested. Cluster size effects have been seen: thiophene adsorbs molecularly with larger binding energies on smaller clusters. However, larger clusters have smaller activation energy for C4H4S bond activation than smaller clusters. The latter is consistent with early catalysis studies. Kinetics and dynamics parameters have been determined quantitatively. We spent a significant amount of time on upgrades of our equipment. A 2nd-hand refurbished X-ray photoelectron spectrometer (XPS) has been integrated into the existing molecular beam scattering system and is already operational (supported by the DoE supplemental grant available in October 2009). We also added a time of flight (TOF) system to the beam scattering apparatus and improved on the accessible impact energy range (new nozzle heater and gas mixing manifold) for the beam scattering experiments. In addition, a GC-based powder atmospheric flow reactor for studies on powder samples is now operational. Furthermore, a 2nd UHV kinetics system has been upgraded as well. In summary, mostly single crystal systems have so far been considered in basic science studies about HDS. Industrial catalysts, however, can be better approximated with the supported cluster systems that we studied in this project. Furthermore, an entirely new class of HDS systems, namely fullerene-like particles and inorganic nanotubes, has been included. Studying new materials and systems has the potential to impact science and technology. The systems investigated are closely related to energy and environmental-related surface science/catalysis. This prior project, conducted at NDSU by a sma

  11. Catalysis Center for Energy Innovation

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    I: Analytical Characterization Instructors: Professor Paul Dauenhauer (University of Minnesota) Jeff Everhart (University of Delaware) 322 ISE Lab 10:45-11:00 Break 11:00-12:30 ...

  12. Electrochemistry: Catalysis at the boundaries

    SciTech Connect (OSTI)

    Appel, Aaron M.

    2014-04-09

    Renewable energy provides an opportunity to power society without the potential impacts from the use of fossil fuels, but a major limitation of sources such as solar and wind is their intermittent availability. Efficient storage of energy from these renewable sources is critical in developing their widespread utilization. One approach to the storage of renewable energy is the production of fuels, such as ethanol, from water and carbon dioxide. Unlike traditional centralized fuel production, electrochemical systems can operate under mild pressures and temperatures in dispersed, small-scale reactors. Renewable sources of energy are inherently dispersed, and therefore are well matched with the production of fuels electrochemically. However, the development of efficient catalysts is essential for the intended chemical transformations.

  13. SEPARATION OF RUTHENIUM COMPOUNDS FROM GASEOUS MIXTURES

    DOE Patents [OSTI]

    Newby, B.J.; Hanson, D.A.; May, C.E.

    1960-12-13

    A process is given for removing RuO/sub 4/ from waste calcination off- gases by adsorption on silica gel, preferably of from 70 to 80 deg C. The RuO/sub 4/ can be eluted from the silica gel with water of a temperature between 60 and 70 deg C.

  14. Model Catalysis of Ammonia Synthesis ad Iron-Water Interfaces - ASum Frequency Generation Vibrational Spectroscopic Study of Solid-GasInterfaces and Anion Photoelectron Spectroscopic Study of Selected Anionclusters

    SciTech Connect (OSTI)

    Ferguson, Michael James

    2005-12-15

    The ammonia synthesis reaction has been studied using single crystal model catalysis combined with sum frequency generation (SFG) vibrational spectroscopy. The adsorption of gases N{sub 2}, H{sub 2}, O{sub 2} and NH{sub 3} that play a role in ammonia synthesis have been studied on the Fe(111) crystal surface by sum frequency generation vibrational spectroscopy using an integrated Ultra-High Vacuum (UHV)/high-pressure system. SFG spectra are presented for the dissociation intermediates, NH{sub 2} ({approx}3325 cm{sup -1}) and NH ({approx}3235 cm{sup -1}) under high pressure of ammonia or equilibrium concentrations of reactants and products on Fe(111) surfaces. Special attention was paid to understand how potassium promotion of the iron catalyst affects the intermediates of ammonia synthesis. An Fe(111) surface promoted with 0.2 monolayers of potassium red shifts the vibrational frequencies of the reactive surface intermediates, NH and NH{sub 2}, providing evidence for weakened the nitrogen-hydrogen bonds relative to clean Fe(111). Spectral features of these surface intermediates persisted to higher temperatures for promoted iron surfaces than for clean Fe(111) surfaces implying that nitrogen-iron bonds are stronger for the promoted surface. The ratio of the NH to NH{sub 2} signal changed for promoted surfaces in the presence of equilibrium concentrations of reactants and products. The order of adding oxygen and potassium to promoted surfaces does not alter the spectra indicating that ammonia induces surface reconstruction of the catalyst to produce the same surface morphology. When oxygen is co-adsorbed with nitrogen, hydrogen, ammonia or potassium on Fe(111), a relative phase shift of the spectra occurs as compared to the presence of adsorbates on clean iron surfaces. Water adsorption on iron was also probed using SFG vibrational spectroscopy. For both H{sub 2}O and D{sub 2}O, the only spectral feature was in the range of the free OH or free OD. From the absence of SFG spectra of ice-like structure we conclude that surface hydroxides are formed and no liquid water is present on the surface. Other than model catalysis, gas phase anion photoelectron spectroscopy of the Cl + H{sub 2} van der Waals well, silicon clusters, germanium clusters, aluminum oxide clusters and indium phosphide clusters were studied. The spectra help to map out the neutral potential energy surfaces of the clusters. For aluminum oxide, the structures of the anions and neutrals were explored and for silicon, germanium and indium phosphide the electronic structure of larger clusters was mapped out.

  15. Combined Use of Residual Dipolar Couplings and Solution X-ray Scattering To Rapidly Probe Rigid-Body Conformational Transitions in a Non-phosphorylatable Active-Site Mutant of the 128 kDa Enzyme I Dimer

    SciTech Connect (OSTI)

    Takayama, Yuki; Schwieters, Charles D.; Grishaev, Alexander; Ghirlando, Rodolfo; Clore, G. Marius (NIH)

    2012-10-23

    The first component of the bacterial phosphotransferase system, enzyme I (EI), is a multidomain 128 kDa dimer that undergoes large rigid-body conformational transitions during the course of its catalytic cycle. Here we investigate the solution structure of a non-phosphorylatable active-site mutant in which the active-site histidine is substituted by glutamine. We show that perturbations in the relative orientations and positions of the domains and subdomains can be rapidly and reliably determined by conjoined rigid-body/torsion angle/Cartesian simulated annealing calculations driven by orientational restraints from residual dipolar couplings and shape and translation information afforded by small- and wide-angle X-ray scattering. Although histidine and glutamine are isosteric, the conformational space available to a Gln side chain is larger than that for the imidazole ring of His. An additional hydrogen bond between the side chain of Gln189 located on the EIN{sup {alpha}/{beta}} subdomain and an aspartate (Asp129) on the EIN{sup {alpha}} subdomain results in a small ({approx}9{sup o}) reorientation of the EIN{sup {alpha}} and EIN{sup {alpha}/{beta}} subdomains that is in turn propagated to a larger reorientation ({approx}26{sup o}) of the EIN domain relative to the EIC dimerization domain, illustrating the positional sensitivity of the EIN domain and its constituent subdomains to small structural perturbations.

  16. Two component-three dimensional catalysis

    DOE Patents [OSTI]

    Schwartz, Michael; White, James H.; Sammells, Anthony F.

    2002-01-01

    This invention relates to catalytic reactor membranes having a gas-impermeable membrane for transport of oxygen anions. The membrane has an oxidation surface and a reduction surface. The membrane is coated on its oxidation surface with an adherent catalyst layer and is optionally coated on its reduction surface with a catalyst that promotes reduction of an oxygen-containing species (e.g., O.sub.2, NO.sub.2, SO.sub.2, etc.) to generate oxygen anions on the membrane. The reactor has an oxidation zone and a reduction zone separated by the membrane. A component of an oxygen containing gas in the reduction zone is reduced at the membrane and a reduced species in a reactant gas in the oxidation zone of the reactor is oxidized. The reactor optionally contains a three-dimensional catalyst in the oxidation zone. The adherent catalyst layer and the three-dimensional catalyst are selected to promote a desired oxidation reaction, particularly a partial oxidation of a hydrocarbon.

  17. Heterogeneous Catalysis and Surface Science - JCAP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Hermann Muller and Mutations in Drosophila Resources with Additional Information Hermann Muller Credit: Hermann Muller, 1956, Hermann J. Muller Collection I; Box 11: Folder 04: Cold Spring Harbor Laboratory Archives Geneticist and Nobel prize laureate [Hermann J.] Muller was born and schooled in New York City, receiving an A.B., M.A. and, in 1915, his Ph.D. from Columbia University. His first faculty appointment was at Rice University in Houston, Texas. He then accepted a two-year appointment as

  18. Method for producing catalysis from coal

    DOE Patents [OSTI]

    Farcasiu, Malvina; Derbyshire, Frank; Kaufman, Phillip B.; Jagtoyen, Marit

    1998-01-01

    A method for producing catalysts from coal is provided comprising mixing an aqueous alkali solution with the coal, heating the aqueous mixture to treat the coal, drying the now-heated aqueous mixture, reheating the mixture to form carbonized material, cooling the mixture, removing excess alkali from the carbonized material, and recovering the carbonized material, wherein the entire process is carried out in controlled atmospheres, and the carbonized material is a hydrocracking or hydrodehalogenation catalyst for liquid phase reactions. The invention also provides for a one-step method for producing catalysts from coal comprising mixing an aqueous alkali solution with the coal to create a mixture, heating the aqueous mixture from an ambient temperature to a predetermined temperature at a predetermined rate, cooling the mixture, and washing the mixture to remove excess alkali from the treated and carbonized material, wherein the entire process is carried out in a controlled atmosphere.

  19. Catalysis using hydrous metal oxide ion exchangers

    DOE Patents [OSTI]

    Dosch, R.G.; Stephens, H.P.; Stohl, F.V.

    1983-07-21

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  20. Hydrodesulfurization catalysis by Chevrel phase compounds

    DOE Patents [OSTI]

    McCarty, Kevin F. (Livermore, CA); Schrader, Glenn L. (Ames, IA)

    1985-12-24

    A process is disclosed for the hydrodesulfurization of sulfur-containing hydrocarbon fuel with reduced ternary molybdenum sulfides, known as Chevrel phase compounds. Chevrel phase compounds of the general composition M.sub.x Mo.sub.6 S.sub.8, with M being Ho, Pb, Sn, Ag, In, Cu, Fe, Ni, or Co, were found to have hydrodesulfurization activities comparable to model unpromoted and cobalt-promoted MoS.sub.2 catalysts. The most active catalysts were the "large" cation compounds (Ho, Pb, Sn), and the least active catalysts were the "small" cation compounds (Cu, Fe, Ni, Co.).

  1. Mesoporous Silica Nanomaterials for Applications in Catalysis...

    Office of Scientific and Technical Information (OSTI)

    horses have ability to deliver Doxorubicin to cancer cells and induce their death. ... was able to transfect cancer cell lines, such as human HeLa and CHO cancer cell lines. ...

  2. Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Laboratory (LBNL) accepts diverse feedstocks to demonstrate the effciency of novel biofuel ... can convert biomass into advanced biofuels in sufficient quantities for engine testing. ...

  3. Catalysis using hydrous metal oxide ion exchanges

    DOE Patents [OSTI]

    Dosch, Robert G.; Stephens, Howard P.; Stohl, Frances V.

    1985-01-01

    In a process which is catalyzed by a catalyst comprising an active metal on a carrier, said metal being active as a catalyst for the process, an improvement is provided wherein the catalyst is a hydrous, alkali metal or alkaline earth metal titanate, zirconate, niobate or tantalate wherein alkali or alkaline earth metal cations have been exchanged with a catalytically effective amount of cations of said metal.

  4. The impact of nanoscience on heterogeneous catalysis

    SciTech Connect (OSTI)

    Bell, Alexis T.

    2003-03-03

    Most catalysts consist of nanometer-sized particles dispersed on a high-surface area support. Advances in characterization methods have led to a molecular level understanding of the relationships between nanoparticle properties and catalytic performance. Together with novel approaches to nanoparticle synthesis, this knowledge is contributing to the design and development of new catalysts.

  5. Basic Research Needs: Catalysis for Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    with heretofore unprecedented detail. Examples of new computational methods include optimization of structures determined experimentally by diffraction scattering based on...

  6. Textured Metal Catalysts for Heterogeneous Catalysis - Energy...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    access to micropores Highly effective for aqueous phase hydrogenations Applications and Industries Bioproductsbiofuels manufacturing Chemical manufacturing Patents and Patent...

  7. [Zeolite catalysis in conversion of cellulosics

    SciTech Connect (OSTI)

    Tsao, G.T.

    1992-12-31

    To transform biomass into fermentable substrate for yeast, we are using zeolites instead of enzymes to catalyze the two bottleneck reactions in biomass conversion, xylose isomerization and ceuobiose hydrolysis. The experimental results on these reactions carried out over various zeolites and other catalysts are presented herein. The advantages and disadvantages of using these catalysts over enzymes are also discussed. Heterogeneous solid catalysts other than zeolites has been employed for cellobiose-to-glucose hydrolysis. The size and shape selectivity that makes zeoutes unique for some reactions can add diffusional hindrance. We have spent some time screening various known solid acidic catalysts. We report that a class of cationic ion exchange resins in the acidified form (e.g. Amberlite) has worked well as an acidic catalyst in hydrolyzing cellobiose to glucose. Our experimental results, together with those obtained from a homogeneous acid catalyst (e.g. sulfuric acid) for comparison are provided. Having succeeded in finding an alternative solid acid catalyst for hydrolysis, we explored other solid resin or other homogeneous but non-enzyme catalyst to carry out the xylose-to-xylulose isomerization. A fairly extensive search has been made. We explored the use of sodium aluminates in the homogeneous phase isomerization of glucose to fructose and obtained a very high conversion of glucose to fructose with the final mixture containing 85% of fructose instead of the common 45%. Fructose apparently complexes with aluminates, and its equilibrium concentration is shifted to considerably higher values than permitted by simple glucose/fructose equilibrium. We have recently found a number of catalysts capable of promoting isomerization between aldoses and ketoses. One solid resin, known as polyvinyl pyridine (PVP), is able to convert xylose to xylulose at a pH below 7. Our usage of alternative isomerization catalysts, including PVP, are described.

  8. [Zeolite catalysis in conversion of cellulosics

    SciTech Connect (OSTI)

    Tsao, G.T.

    1992-01-01

    To transform biomass into fermentable substrate for yeast, we are using zeolites instead of enzymes to catalyze the two bottleneck reactions in biomass conversion, xylose isomerization and ceuobiose hydrolysis. The experimental results on these reactions carried out over various zeolites and other catalysts are presented herein. The advantages and disadvantages of using these catalysts over enzymes are also discussed. Heterogeneous solid catalysts other than zeolites has been employed for cellobiose-to-glucose hydrolysis. The size and shape selectivity that makes zeoutes unique for some reactions can add diffusional hindrance. We have spent some time screening various known solid acidic catalysts. We report that a class of cationic ion exchange resins in the acidified form (e.g. Amberlite) has worked well as an acidic catalyst in hydrolyzing cellobiose to glucose. Our experimental results, together with those obtained from a homogeneous acid catalyst (e.g. sulfuric acid) for comparison are provided. Having succeeded in finding an alternative solid acid catalyst for hydrolysis, we explored other solid resin or other homogeneous but non-enzyme catalyst to carry out the xylose-to-xylulose isomerization. A fairly extensive search has been made. We explored the use of sodium aluminates in the homogeneous phase isomerization of glucose to fructose and obtained a very high conversion of glucose to fructose with the final mixture containing 85% of fructose instead of the common 45%. Fructose apparently complexes with aluminates, and its equilibrium concentration is shifted to considerably higher values than permitted by simple glucose/fructose equilibrium. We have recently found a number of catalysts capable of promoting isomerization between aldoses and ketoses. One solid resin, known as polyvinyl pyridine (PVP), is able to convert xylose to xylulose at a pH below 7. Our usage of alternative isomerization catalysts, including PVP, are described.

  9. Catalysis Working Group | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... Design and develop oxygen reduction reactionoxygen evolution reaction (ORROER) bi-functional oxide catalysts. Develop new classes of non-PGM electrocatalysts for HOR in alkaline ...

  10. Ruthenium on Carbon Nanostructures for Supercapacitor Electrodes - Energy

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Russell Hulse, the First Binary Pulsar, and Science Education Resources with Additional Information 'Dr. Russell A. Hulse of Princeton University, the discoverer of the first binary pulsar and co-recipient of the 1993 Nobel Prize in physics, will affiliate with The University of Texas at Dallas (UTD) as a visiting professor of physics and of science and math education, beginning in January 2004. Russell Hulse Courtesy Princeton Plasma Physics Laboratory Hulse will be involved with developing

  11. Molecular water oxidation catalyst

    DOE Patents [OSTI]

    Gratzel, Michael; Munavalli, Shekhar; Pern, Fu-Jann; Frank, Arthur J.

    1993-01-01

    A dimeric composition of the formula: ##STR1## wherein L', L", L'", and L"" are each a bidentate ligand having at least one functional substituent, the ligand selected from bipyridine, phenanthroline, 2-phenylpyridine, bipyrimidine, and bipyrazyl and the functional substituent selected from carboxylic acid, ester, amide, halogenide, anhydride, acyl ketone, alkyl ketone, acid chloride, sulfonic acid, phosphonic acid, and nitro and nitroso groups. An electrochemical oxidation process for the production of the above functionally substituted bidentate ligand diaqua oxo-bridged ruthenium dimers and their use as water oxidation catalysts is described.

  12. Pressure dependence of the exchange interaction in the dimeric single-molecule magnet [Mn{sub 4}O{sub 3}Cl{sub 4}(O{sub 2}CEt){sub 3}(py){sub 3}]{sub 2} from inelastic neutron scattering

    SciTech Connect (OSTI)

    Sieber, A.; Waldmann, O.; Ochsenbein, S. T.; Carver, G.; Guedel, H. U.; Foguet-Albiol, D.; Christou, G.; Mutka, H.; Fernandez-Alonso, F.; Mezouar, M.; Weber, H. P.

    2006-07-01

    The low-lying magnetic excitations in the dimers of single-molecule magnets [Mn{sub 4}O{sub 3}Cl{sub 4}(O{sub 2}CEt){sub 3}(py){sub 3}]{sub 2}, or (Mn{sub 4}){sub 2}, are studied by inelastic neutron scattering as a function of hydrostatic pressure. The anisotropy parameters D and B{sub 0}{sup 4}, which describe each Mn{sub 4} subunit, are essentially pressure independent, while the antiferromagnetic exchange coupling J between the two Mn{sub 4} subunits strongly depends on pressure, with an increase of 42% at 17 kbar. Additional pressure-dependent powder x-ray measurements allow a structural interpretation of the findings.

  13. Fundamental Studies in Catalysis Enabled the use of Efficient...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... The technology has since been used on other fuel efficient diesel vehicles in the U.S. market, including the Volkswagen Jetta TDI. In addition to supporting this market success ...

  14. Method for producing high surface area chromia materials for catalysis

    DOE Patents [OSTI]

    Gash, Alexander E.; Satcher, Joe; Tillotson, Thomas; Hrubesh, Lawrence; Simpson, Randall

    2007-05-01

    Nanostructured chromium(III)-oxide-based materials using sol-gel processing and a synthetic route for producing such materials are disclosed herein. Monolithic aerogels and xerogels having surface areas between 150 m.sup.2/g and 520 m.sup.2/g have been produced. The synthetic method employs the use of stable and inexpensive hydrated-chromium(III) inorganic salts and common solvents such as water, ethanol, methanol, 1-propanol, t-butanol, 2-ethoxy ethanol, and ethylene glycol, DMSO, and dimethyl formamide. The synthesis involves the dissolution of the metal salt in a solvent followed by an addition of a proton scavenger, such as an epoxide, which induces gel formation in a timely manner. Both critical point (supercritical extraction) and atmospheric (low temperature evaporation) drying may be employed to produce monolithic aerogels and xerogels, respectively.

  15. EERE Success Story-Fundamental Studies in Catalysis Enabled the...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Understanding why the technology wasn't working required scientists to improve their ... In 2003, with funding from VTO, Cummins and PNNL began a collaborative, multi-year ...

  16. Model catalysis by size-selected cluster deposition

    SciTech Connect (OSTI)

    Anderson, Scott

    2015-11-20

    This report summarizes the accomplishments during the last four years of the subject grant. Results are presented for experiments in which size-selected model catalysts were studied under surface science and aqueous electrochemical conditions. Strong effects of cluster size were found, and by correlating the size effects with size-dependent physical properties of the samples measured by surface science methods, it was possible to deduce mechanistic insights, such as the factors that control the rate-limiting step in the reactions. Results are presented for CO oxidation, CO binding energetics and geometries, and electronic effects under surface science conditions, and for the electrochemical oxygen reduction reaction, ethanol oxidation reaction, and for oxidation of carbon by water.

  17. Catalysis Working Group Kick-Off Meeting: May 2012 | Department...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Sanjeev Mukerjee, Northeastern University Catalyst Working Group Kick-off Meeting: Personal Commentary, Mark Debe, 3M Operando Raman and Theoretical Vibration Spectroscopy of ...

  18. Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    into gasoline, jet fuel, and other products. PDF icon thermochemicalfourpager.pdf More Documents & Publications 2013 Peer Review Presentations-Bio-oil 2013 Peer Review ...

  19. Catalysis by Design: Bridging the Gap Between Theory and Experiments...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    by Design: Bridging the Gap Between Theory and Experiments at Nanoscale Level Studies on a simple platinum-alumina system constitute a first step toward a "catalyst by design" ...

  20. Temperature Transient Effects in Plasma-Catalysis | Department...

    Broader source: Energy.gov (indexed) [DOE]

    of Temperature and Hydrocarbon Species on the Product Distribution from a Non-Thermal Plasma Reactor Development of NOx Adsorber System for Dodge Ram 2007 Heavy duty Pickup Truck

  1. Transition metal catalysis in the generation of natural gas

    SciTech Connect (OSTI)

    Mango, F.D.

    1995-12-31

    The view that natural gas is thermolytic, coming from decomposing organic debris, has remained almost unchallenged for nearly half a century. Disturbing contradictions exist, however: Oil is found at great depth, at temperatures where only gas should exist and oil and gas deposits show no evidence of the thermolytic debris indicative of oil decomposing to gas. Moreover, laboratory attempts to duplicate the composition of natural gas, which is typically between 60 and 95+ wt% methane in C{sub 1}-C{sub 4}, have produced insufficient amounts of methane (10 to 60%). It has been suggested that natural gas may be generated catalytically, promoted by the transition metals in carbonaceous sedimentary rocks. This talk will discuss experimental results that support this hypothesis. Various transition metals, as pure compounds and in source rocks, will be shown to generate a catalytic gas that is identical to natural gas. Kinetic results suggest robust catalytic activity under moderate catagenetic conditions.

  2. Catalysis Center for Energy Innovation KEY ACCOMPLISHMENTS AND...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    . . . . . . . . . . . . . 6 Computational Engine Drives Catalyst Discovery . . . . . . . . ... Glucose EMF can be used as a potential biofuel additive either directly or after ...

  3. Fuel Synthesis Catalysis Laboratory (Fact Sheet), NREL (National...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Fuel Synthesis Catalyst Testing Equipment Specifications Systems 10 mL isothermal tubular ... Massatomic balances 3% typical This bench-scale fuel synthesis reactor can be used to ...

  4. Theoretical Study on Catalysis by Protein Enzymes and Ribozyme

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    determine the catalytic mechanism in the presence of the enzyme environment, a combined quantummolecular mechanics (QMMM) approach is used, performed with the CHARMM program....

  5. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Broader source: Energy.gov (indexed) [DOE]

    Presentation given at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER ... PDF icon deer07rappe.pdf More Documents & Publications Low-Temperature HydrocarbonCO ...

  6. Biphasic catalysis in water/carbon dioxide micellar systems

    DOE Patents [OSTI]

    Jacobson, Gunilla B.; Tumas, William; Johnston, Keith P.

    2002-01-01

    A process is provided for catalyzing an organic reaction to form a reaction product by placing reactants and a catalyst for the organic reaction, the catalyst of a metal complex and at least one ligand soluble within one of the phases of said aqueous biphasic system, within an aqueous biphasic system including a water phase, a dense phase fluid, and a surfactant adapted for forming an emulsion or microemulsion within the aqueous biphasic system, the reactants soluble within one of the phases of the aqueous biphasic system and convertible in the presence of the catalyst to a product having low solubility in the phase in which the catalyst is soluble; and, maintaining the aqueous biphasic system under pressures, at temperatures, and for a period of time sufficient for the organic reaction to occur and form the reaction product and to maintain sufficient density on the dense phase fluid, the reaction product characterized as having low solubility in the phase in which the catalyst is soluble.

  7. Technology development for iron fisher-tropsch catalysis

    SciTech Connect (OSTI)

    Davis, B.H.

    1997-07-15

    The goal of the proposed work is the development of iron-based Fischer-Tropsch catalysts that combined high activity, selectivity and life with physical robustness for slurry phase reactors that will produce either low-alpha or high-alpha products. the catalyst that is developed will be suitable for testing at the Advanced Fuels Development Facility at LaPorte, Texas or similar sized plant. Previous work by the offeror has produced a catalyst formulation that is 1.5 times as active as the standard-catalyst developed by German workers for slurry phase synthesis, The proposed work will optimize the catalyst composition and pretreatment operation for this low-alpha catalyst. In parallel, work will be conducted to design a high-alpha iron catalyst that is suitable for slurry phase synthesis. Studies will be conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. the oxidation/reduction cycles that are anticipated to occur in large, commercial reactors will be studies at the laboratory scale. Catalyst performance will be determined for catalysts synthesized in this program for activity, selectivity, and aging characteristics.

  8. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    were able to directly observe redox processes in thin-film iron and cobalt perovskite oxide electrocatalysts using surface-sensitive, x-ray absorption spectroscopy while...

  9. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    DOE Patents [OSTI]

    Hilsenbeck, Shane J. (Ames, IA); McCarley, Robert E. (Ames, IA); Schrader, Glenn L. (Ames, IA); Xie, Xiaobing (College Station, TX)

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M.sup.n+.sub.2x/n (L.sub.6 S.sub.8)S.sub.x, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M.sub.6 S.sub.8).sup.0 cluster units are present. Vacuum thermolysis of the amorphous Na.sub.2x (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH first produces poorly crystalline NaMo.sub.6 S.sub.8 by disproportionation at 800.degree. C. and well-crystallized NaMo.sub.6 S.sub.8 at .gtoreq. 900.degree. C. Ion-exchange of the sodium material in methanol with soluble M.sup.2+ and M.sup.3+ salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M.sup.n+.sub.2x/n (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M.sup.n+.sub.2x/n Mo.sub.6 S.sub.8+x (MeOH).sub.y MMOS! (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as "Chevrel phase-like" in that both contain Mo.sub.6 S.sub.8 cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst showed to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS.sub.2 catalysts.

  10. Lean NOx Catalysis Research and Development | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    3 DEER Conference Presentation: Caterpillar, Inc. PDF icon 2003_deer_park.pdf More Documents & Publications Lean-NOx Catalyst Development for Diesel Engine Applications Fuel Effects on Emissions Control Technologies

  11. Study of catalysis of coal gasification at elevated pressures...

    Office of Scientific and Technical Information (OSTI)

    EXPERIMENTS; CARBON; CATALYSTS; COMPARATIVE EVALUATIONS; HYDROGEN; MEDIUM PRESSURE; METHANE; NICKEL; PRODUCTION; STEAM; VERY HIGH TEMPERATURE; ALKANES; CRYOGENIC FLUIDS; ...

  12. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    most promising renewable energy technologies-fuel cells, water splitters, and artificial photosynthesis-rely upon catalysts to expedite the chemical reactions. Catalysts are...

  13. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ...-temperature oxidation of hydrocarbons and CO in homogeneous charge compression ignition (HCCI) emissions. PDF icon deer08rappe.pdf More Documents & Publications Low-Temperature ...

  14. Oxygen Catalysis: The Other Half of the Equation

    SciTech Connect (OSTI)

    Turner, J.

    2008-10-01

    Artificial photosynthesis--splitting water with light--is an attractive way to make hydrogen, but what happens to the oxygen? A catalyst that aids in the efficient production of gaseous oxygen improves the viability of this approach.

  15. Rare-earth nanoparticles for catalysis | The Ames Laboratory

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Developing new materials based on these two elements is expected to impact favorably the supply chain of the more scarce rare earths. The SULI student in this program will work...

  16. University of Delaware | Catalysis Center for Energy Innovation | Aromatics

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Research Thrust Green Aromatics Transition state for the Diels-Alder reaction of 2,5-dimethylfuran and ethylene in zeolite LiY Most polymers and plastics require six-carbon ring structures. Sugars (such as glucose and xylose) derived from cellulose and hemicellulose are converted into five-atom ring structures called furans, which consist of four carbons and one oxygen. In order to make the right carbon atom ring, CCEI has introduced technology for the production of aromatics from furans by

  17. University of Delaware | Catalysis Center for Energy Innovation | Biomass

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Upgrade Biomass Upgrade Upgrade of furans via hydrodeoxygenation technology. Bio-oil and oxygenated intermediates derived from sugars are oxygen rich. In order to be transformed to fuels and chemicals, selective oxygen removal is required. CCEI develops the hydrodeoxygenation science to improve product yields, introduce new chemicals, and reduce catalyst cost with optimal hydrogen management. We have developed the first high-yield catalytic transfer hydrogenation technology to reduce furans

  18. University of Delaware | Catalysis Center for Energy Innovation | Fuel

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Cells Research Thrust Fuel Cells Schematic for a large-scale DCFC system based on molten Sb anodes. CCEI's technology is based on electrolytes that are ceramic oxygen-ion conductors, such as cubic zirconia. It uses molten antimony (Sb) as the fuel electrode. Inside the fuel cell, Sb is oxidized at the electrolyte interface to Sb2O3, producing electrical power. The Sb2O3 is in turn reduced by carbon-based fuels to regenerate the Sb, allowing the cycle to start again

  19. University of Delaware | Catalysis Center for Energy Innovation | Furans

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Research Thrust Sugars to Furans Converting sugars to high-value intermediates. CCEI introduced an iconic technology for the isomerization of aldoses to ketoses production via Sn-beta zeolite and other related heterogeneous and homogeneous Lewis acid catalysts in water and demonstrated that this technology is broadly applicable to the conversion of C6 and C5 sugars. Researchers discovered the first single-pot process that combines heterogeneous Lewis acidity with Bronsted acidity to carry

  20. University of Delaware | Catalysis Center for Energy Innovation | Materials

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Materials Bi-modal silica nanoparticle templates for synthesizing 3D ordered mesoporous replicas of various oxides. CCEI has a growing portfolio of novel classes of materials with tunable micro-, meso-, and/or hierarchical pores and functional groups, including: (1) three-dimensionally ordered mesoporous (3DOm) carbons, titanias, and zirconias (2) 3DOm-imprinted zeolites (3) hollow mesoporous carbons (4) hierarchically porous MFI and MEL zeolites These materials hold exciting implications for

  1. University of Delaware | Catalysis Center for Energy Innovation | Pyrolysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Research Thrust Pyrolysis Thin-film pyrolysis sample. The next generation of biofuels will be produced by high-temperature (>1000 °F) pyrolysis or gasification of lignocellulosic biomass. At these temperatures, large biopolymers (such as cellulose) thermally fracture to smaller fragments, which can evaporate and be collected as bio-oil. Subsequent upgrading of bio-oil then produces gasoline, diesel and jet fuel. Thus, the future of biofuels depends on the production of high-quality,

  2. Density Functional Theory in Surface Chemistry and Catalysis

    SciTech Connect (OSTI)

    Norskov, Jens

    2011-05-19

    Recent advances in the understanding of reactivity trends for chemistry at transition metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. Current status of the field is discussed with an emphasis on the role of coupling between theory and experiment and future challenges.

  3. Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    A wide variety of non-food biomass grown across the country can be converted into advanced ... to convert domestic, non-food biomass into gasoline, diesel, jet fuel, and other products. ...

  4. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    vice versa. At the ALS, researchers were able to directly observe redox processes in thin-film iron and cobalt perovskite oxide electrocatalysts using surface-sensitive, x-ray...

  5. Plasma Assisted Catalysis System for NOx Reduction | Department of Energy

    Broader source: Energy.gov (indexed) [DOE]

    Photo of a photovoltaic system. Planning for the federal site solar project can begin after the solar solar pre-screening is complete. The project planning includes the following steps: Identify needs and goals >> Assemble an on-site team >> Evaluate the site's solar screening >> Consider project requirements and recommendations >> Make a financing and contracting decision >> This section walks through the steps needed to execute a specific site solar procurement

  6. Visualizing Group II Intron Catalysis through the Stages of Splicing...

    Office of Scientific and Technical Information (OSTI)

    APA Chicago Bibtex Export Metadata Endnote Excel CSV XML Save to My Library Send to Email Send to Email Email address: Content: Close Send Cite: MLA Format Close Cite: APA ...

  7. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    DOE Patents [OSTI]

    Hilsenbeck, S.J.; McCarley, R.E.; Schrader, G.L.; Xie, X.B.

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M{sup n+}{sub 2x/n}(L{sub 6}S{sub 8})S{sub x}, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M{sub 6}S{sub 8}){sup 0} cluster units are present. Vacuum thermolysis of the amorphous Na{sub 2x}(Mo{sub 6}S{sub 8})S{sub x}{hor_ellipsis}yMeOH first produces poorly crystalline NaMo{sub 6}S{sub 8} by disproportionation at 800 C and well-crystallized NaMo{sub 6}S{sub 8} at {>=} 900 C. Ion-exchange of the sodium material in methanol with soluble M{sup 2+} and M{sup 3+} salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M{sup n+}{sub 2x/n}(Mo{sub 6}S{sub 8})S{sub x}{hor_ellipsis}yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M{sup n+}{sub 2x/n}Mo{sub 6}S{sub 8+x}(MeOH){sub y}[MMOS] (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as ``Chevrel phase-like`` in that both contain Mo{sub 6}S{sub 8} cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst is shown to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS{sub 2} catalysts. 9 figs.

  8. Catalysis Center for Energy Innovation: University of Delaware

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. ... and hemicellulose, the production of green aromatics, the hydrodeoxygenation of ...

  9. Role of acid catalysis in dimethyl ether conversion processes

    SciTech Connect (OSTI)

    Tartamella, T.L.; Lee, S.

    1996-12-31

    Acidity plays an important role in the conversion of methanol and dimethyl ether (DME) to hydrocarbons and oxygenates. In the conversion to hydrocarbons over zeolite catalyst, Broensted acidity is the main contributor to the first hydrocarbon formed. Here, acidity is also an important factor in determining olefin, paraffin, and aromatic content in the final product distribution. Catalyst life has also been found to be related to acidity content in zeolites. DME conversion to oxygenates is especially dependent on high acidity catalysts. Superacids like BF{sub 3}, HF-BF{sub 3}, and CF{sub 3}COOH have been used in the past for conversion of DME in carbonylation reactions to form methyl acetate and acetic acid at high pressures. Recently, heteropoly acids and their corresponding metal substituted salts have been used to convert DME to industrially important petrochemicals resulting in shorter reaction times and without the use of harsh operating conditions.

  10. Nanostructured transition metal oxides useful for water oxidation catalysis

    DOE Patents [OSTI]

    Frei, Heinz M; Jiao, Feng

    2013-12-24

    The present invention provides for a composition comprising a nanostructured transition metal oxide capable of oxidizing two H.sub.2O molecules to obtain four protons. In some embodiments of the invention, the composition further comprises a porous matrix wherein the nanocluster of the transition metal oxide is embedded on and/or in the porous matrix.

  11. Technology Development for Iron Fischer-Tropsch Catalysis.

    SciTech Connect (OSTI)

    Davis, B.H.

    1997-12-16

    The goal of the proposed work is the development of iron-based Fischer-Tropsch catalysts that combined high activity, selectivity and life with physical robustness for slurry phase reactors that will produce either low-alpha or high-alpha products. The catalyst that is developed will be suitable for testing at the Advanced Fuels Development Facility at LaPorte, Texas or similar sized plant. Previous work by the offeror has produced a catalyst formulation that is 1.5 times as active as the `standard-catalyst` developed by German workers for slurry phase synthesis. The proposed work will optimize the catalyst composition and pretreatment operation for this low-alpha catalyst. In parallel, work will be conducted to design a high-alpha iron catalyst that is suitable for slurry phase synthesis. Studies will be conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. The oxidation/reduction cycles that are anticipated to occur in large, commercial reactors will be studied at the laboratory scale. Catalyst performance will be determined for catalysts synthesized in this program for activity, selectivity and aging characteristics.

  12. Hangman Catalysis for Photo- and Photoelectro- Chemical Activation of Water

    SciTech Connect (OSTI)

    Nocera, Daniel

    2014-04-15

    The focus of this DOE program is solar fuels specifically the chemistry for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) from water and the oxygen reduction reaction (ORR) to water These three reactions are at the heart of renewable energy conversion. The bond-making and bond-breaking chemistry that underpins these transformations is not well understood. We are developing insight into such chemistry by creating a series of ligand constructs that poise an acid-base functionality over a redox active metal platform. These hangman ligands utilize the acid-base functionality to form a secondary coordination sphere that can assist proton movement and facilitate substrate assembly and activation within the molecular cleft. The grant period funding cycle focused on synthesis and reactivity of hangman porphyrins and corroles for HER, OER and ORR.

  13. ALS X-Rays Shine a New Light on Catalysis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    for use as catalysts at the heart of a basic chemical reaction known as ... One of the best examples is water splitting. Electricity generated from the sun via solar ...

  14. Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith

    DOE Patents [OSTI]

    Hilsenbeck, Shane J.; McCarley, Robert E.; Schrader, Glenn L.; Xie, Xiaobing

    1999-02-16

    New amorphous molybdenum/tungsten sulfides with the general formula M.sup.n+.sub.2x/n (L.sub.6 S.sub.8)S.sub.x, where L is molybdenum or tungsten and M is a ternary metal, has been developed. Characterization of these amorphous materials by chemical and spectroscopic methods (IR, Raman, PES) shows that the (M.sub.6 S.sub.8).sup.0 cluster units are present. Vacuum thermolysis of the amorphous Na.sub.2x (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH first produces poorly crystalline NaMo.sub.6 S.sub.8 by disproportionation at 800.degree. C. and well-crystallized NaMo.sub.6 S.sub.8 at .gtoreq. 900.degree. C. Ion-exchange of the sodium material in methanol with soluble M.sup.2+ and M.sup.3+ salts (M=Sn, Co, Ni, Pb, La, Ho) produces the M.sup.n+.sub.2x/n (Mo.sub.6 S.sub.8)S.sub.x .multidot.yMeOH compounds. Additionally, the new reduced ternary molybdenum sulfides with the general formula M.sup.n+.sub.2x/n Mo.sub.6 S.sub.8+x (MeOH).sub.y ›MMOS! (M=Sn, Co, Ni) is an effective hydrodesulfurization (HDS) catalyst both as-prepared and after a variety of pretreatment conditions. Under specified pretreatment conditions with flowing hydrogen gas, the SnMoS type catalyst can be stabilized, and while still amorphous, can be considered as "Chevrel phase-like" in that both contain Mo.sub.6 S.sub.8 cluster units. Furthermore, the small cation NiMoS and CoMoS type pretreated catalyst showed to be very active HDS catalysts with rates that exceeded the model unpromoted and cobalt-promoted MoS.sub.2 catalysts.

  15. The Catalysis Center for Energy Innovation is an Energy Frontier...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    State faculty, he has received a number of awards, including a DARPA Young Faculty Award, ... Research in his laboratory is currently sponsored by NSF, DOE-BES, DARPA, AFOSR, AFRL, ...

  16. Catalysis by Design: Bridging the Gap between Theory and Experiments |

    Broader source: Energy.gov (indexed) [DOE]

    Department of Energy Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 August, 2007, Detroit, Michigan. Sponsored by the U.S. Department of Energy's (DOE) Office of FreedomCAR and Vehicle Technologies (OFCVT). PDF icon deer07_narula.pdf More Documents & Publications Catalysts via First Principles Catalysts via First Principles

  17. Electron Microscopy Catalysis Projects: Success Stories from the High

    Broader source: Energy.gov (indexed) [DOE]

    The U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Fuel Cell Technologies Office (FCTO) held the Electrolytic Hydrogen Production Workshop on February 27-28, 2014, at The National Renewable Energy Laboratory (NREL) in Golden, Colorado, to discuss and share information on the research, development, and demonstration (RD&D) needs for enabling low-cost, effective hydrogen production from all types of water electrolysis systems, both centralized and

  18. ©2013 Catalysis Center for Energy Innovation * University of...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    biomass sources and feed them directly into their process, Catalytic Fast Pyrolysis (CFP). Within the reactor, particles of biomass are rapidly heated within seconds to 900 F, ...

  19. Multipole plasmon excitations of C{sub 60} dimers

    SciTech Connect (OSTI)

    Moradi, Afshin

    2014-07-14

    We study the multipole plasmon mode frequencies of a pair of C{sub 60} molecules by means of the linearized hydrodynamic theory for electronic excitations on the each C{sub 60} surface. We apply the two-center spherical coordinate system for mathematical convenience and find an explicit form of the surface plasmon energies. Numerical result shows when approaching the two C{sub 60} molecules, the coupling between the bare plasmon modes leads to the appearance of additional modes having energies that are different from those of the isolated C{sub 60} molecules.

  20. Selective oxidative synthesis of meso-beta fused porphyrin dimers

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Selecting a New Water Heater Selecting a New Water Heater Water heater testing facility at Oak Ridge National Laboratory. Water heater testing facility at Oak Ridge National Laboratory. When selecting a new water heater for your home, choose a water heating system that will not only provide enough hot water but also that will do so energy efficiently, saving you money. This includes considering the different types of water heaters available and determining the right size and fuel source for your

  1. Molecular dynamics simulations and thermochemistry of reactive ion etching of silicon by chlorine, chlorine dimer, bromine, and bromine dimer cations

    SciTech Connect (OSTI)

    Valone, S.M.; Hanson, D.E.; Kress, J.D.

    1998-05-08

    Simulations of Cl plasma etch of Si surfaces with MD techniques agree reasonably well with the available experimental information on yields and surface morphologies. This information has been supplied to a Monte Carlo etch profile resulting in substantial agreement with comparable inputs provided through controlled experiments. To the extent that more recent measurements of etch rates are more reliable than older ones, preliminary MD simulations using bond-order corrections to the atomic interactions between neighboring Si atoms on the surface improves agreement with experiment through an increase in etch rate and improved agreement with XPS measurements of surface stoichiometry. Thermochemical and geometric analysis of small Si-Br molecules is consistent with the current notions of the effects of including brominated species in etchant gases.

  2. Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst

    SciTech Connect (OSTI)

    Abrevaya, H.

    1991-01-01

    The objective of this contract is to examine the relationship between catalytic properties and the function of cobalt Fischer-Tropsch catalysts and to apply this fundamental knowledge to the development of a stable cobalt-based catalyst with a low methane-plus-ethane selectivity for use in slurry reactors. An experimental cobalt catalyst 585R2723 was tested three times in the fixed-bed reactor. The objective of the tests was to identify suitable testing conditions for screening catalyst. The {alpha}-alumina was determined to be a suitable diluent medium for controlling the catalyst bed temperature close to the inlet temperature. With 13 g of catalyst and 155 g of diluent, the catalyst maximum temperature were within 2{degree}C from the inlet temperatures. As a result of this work, 210{degree}C and 21 atm were shown to result in low methane selectivity and were used as initial conditions in the catalyst screening test. Ethane, which along with methane is undesirable, is typically produced with low selectivity and follows the same trend as methane. Other work reported here indicated that methane selectivity increases with increasing temperature but is not excessively high at 230{degree}C. Consequently, the catalyst screening test should include an evaluation of the catalyst performance at 230{degree}C. During Run 67, the increase in temperature from 210{degree}C to 230{degree}C was initiated at 30 hours on-stream.

  3. Iridium−Ruthenium Alloyed Nanoparticles for the Ethanol Oxidation Fuel Cell Reactions

    SciTech Connect (OSTI)

    Su D.; Du, W.; Deskins, N.A.; Teng, X.

    2012-06-01

    In this study, carbon supported Ir-Ru nanoparticles with average sizes ranging from 2.9 to 3.7 nm were prepared using a polyol method. The combined characterization techniques, that is, scanning transmission electron microscopy equipped with electron energy loss spectroscopy, high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction, were used to determine an Ir-Ru alloy nanostructure. Both cyclic voltammetry and chronoamperometry (CA) results demonstrate that Ir{sub 77}Ru{sub 23}/C bears superior catalytic activities for the ethanol oxidation reaction compared to Ir/C and commercial Pt/C catalysts. In particular, the Ir{sub 77}Ru{sub 23}/C catalyst shows more than 21 times higher mass current density than that of Pt/C after 2 h reaction at a potential of 0.2 V vs Ag/AgCl in CA measurement. Density functional theory simulations also demonstrate the superiority of Ir-Ru alloys compared to Ir for the ethanol oxidation reaction.

  4. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis ... catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis ...

  5. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Switch to Detail View for this search SciTech Connect Search Results Page 1 of 1 Search for: All records Creators/Authors contains: "Masutani, Chikahide" × Sort by Relevance Sort by Date (newest first) Sort by Date (oldest first) Sort by Relevance « Prev Next » Everything2 Electronic Full Text0 Citations2 Multimedia0 Datasets0 Software0 Filter Results Filter by Subject alignment (1) catalysis (1) congenital diseases (1) crystal structure (1) dimers (1) dna (1) dna polymerases (1)

  6. This research was supported as part of the Catalysis Center for Energy Innovatio

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    A Direct Carbon Fuel Cell with a Molten Antimony Anode This research was conducted by the groups of Ray Gorte and John Vohs at the University of Pennsylvania and Doug Buttrey at the University of Delaware. In order to secure our energy future, researchers have been working to develop technology capable of efficiently producing energy from cheap and abundant solid carbonaceous fuel resources, like coal and renewable biomass. Much research has been devoted to developing direct carbon fuel cells

  7. This research was supported as part of the Catalysis Center for Energy Innovatio

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Computational Methods Predict Thermochemistry and Kinetics of Biomass Derivatives on Transition Metals This research was conducted by the groups of Dion Vlachos, Jingguang Chen and Mark Barteau at the University of Delaware. First-principle simulation of biomass processing is hindered by the sheer size of biomass derivatives and the associated computational cost of quantum calculations. Researchers at the University of Delaware developed a new framework for estimating thermochemistry of

  8. This research was supported as part of the Catalysis Center for Energy Innovatio

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    This research was conducted by the group of Mark Davis at the California Institute of Technology. The core of catalytic chemistry research lies in understanding the role of a catalyst in a reaction. This understanding is crucial to the discovery of new materials leading to more energy efficient and benign chemical transformations. A critical reaction in utilization of the most abundant biomass ingredient, cellulose, is the conversion of glucose to fructose. Researchers at Caltech have now

  9. This research was supported as part of the Catalysis Center for Energy Innovatio

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    New Catalyst Converts Selectively Biomass-Derived Sugars to Chemicals This research was conducted by the group of Mark Davis at the California Institute of Technology. A novel catalyst was developed to efficiently convert biomass derived sugars. This development can have unprecedented impact on the production of renewable chemicals and fuels. Interest in carbohydrate chemistry has been revitalized by the recent push to produce chemicals from biomass. A reaction of particular importance and

  10. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support of HCCI Emission Control

    Broader source: Energy.gov [DOE]

    2009 DOE Hydrogen Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting, May 18-22, 2009 -- Washington D.C.

  11. Organusulfur Catalysis With Reduced Molybdenum Sulfides Containing the Mo6S8 Cluster

    SciTech Connect (OSTI)

    Thomas Jay Paskach

    2002-08-27

    Industrial synthesis of sulfur-containing organic chemicals basically focuses on the broad categories of mercaptans (thiols), alkylsulfides (thioethers), polysulfides, and thiophenes. Of the organo-sulfur compounds produced, by far the most important in terms of quantities produced is methyl mercaptan (methanethiol or MeSH), which is produced mainly for the downstream production of methionine and methanesulfonyl chloride. Higher thiols are also used in the manufacture of rubber and plastics as polymerization regulators, chain transfer agents, or initiators. Other important organosulfur chemicals are dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), both of which are used extensively for presulfiding of industrial hydroprocessing catalysts, and substituted thiophenes which are used as intermediates for production of agrochemicals, dyes, and pharmaceuticals. Thiols are produced commercially at the rate of about 10{sup 4} ton/yr from hydrogen sulfide (H{sub 2}S) and alcohols or olefins, using homogeneous free-radical synthesis, or heterogeneous catalysts based on solid acids or supported metal oxides and/or sulfides. Despite this large production rate, and the industrial importance of the organosulfur compounds, only limited research has been devoted to the development of new catalytic materials for their synthesis. Additionally, for most organosulfur catalytic reactions, only limited information exists about reaction mechanisms, active sites, adsorbed surface species, and especially the nature of the catalysts under reaction conditions.

  12. Surface functionalization of metal?organic polyhedron for homogeneous cyclopropanation catalysis

    SciTech Connect (OSTI)

    Lu, Weigang; Yuan, Daqiang; Yakovenko, Andrey; Zhou, Hong-Cai

    2012-03-13

    A super-paddlewheel (comprised of two paddlewheels) metal-organic polyhedron (MOP) containing surface hydroxyl groups was synthesized and characterized. Condensation reactions with linear alkyl anhydrides lead to new MOPs with enhanced solubility. As a result, the surface-modified MOP 4 was demonstrated as a homogeneous Lewis-acid catalyst.

  13. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support of HCCI Emission Control

    Broader source: Energy.gov [DOE]

    Development of catalyst materials to facilitate the low-temperature oxidation of hydrocarbons and CO in homogeneous charge compression ignition (HCCI) emissions.

  14. Synergies of PCCI-Type Combustion and Lean NOx Trap Catalysis for Diesel Engines

    SciTech Connect (OSTI)

    Parks, II, James E; Prikhodko, Vitaly Y; Kass, Michael D; Huff, Shean P

    2008-01-01

    It is widely recognized that future NOx and PM emission targets for diesel engines cannot be met solely via advanced combustion over the full engine drive cycle. Therefore some combination of advanced combustion methodology with an aftertreatment technology will be required. In this study, NOx reduction, fuel efficiency, and regeneration performance of lean NOx trap (LNT) were evaluated for four operating conditions. The combustion approaches included baseline engine operation with and without EGR, two exhaust enrichment methods (post injection and delayed injection), and one advanced combustion mode to enable high efficiency clean combustion (HECC). A 1.7 liter 4-cylinder diesel engine was operated under five conditions, which represent key interest points for light-duty diesel operation. At the low load setting the exhaust temperature was too low to enable LNT regeneration and oxidation; however, HECC (low NOx) was achievable. HECC was also reached under more moderate loads and the exhaust temperatures were high enough to enable even further NOx reductions by the LNT. At high loads HECC becomes difficult but the LNT performance improves and acceptable regeneration can be met with enrichment methodologies.

  15. Synthesis and oxidation catalysis of [tris(oxazolinyl)borato]cobalt(II) scorpionates

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Reinig, Regina R.; Mukherjee, Debabrata; Weinstein, Zachary B.; Xie, Weiwei; Albright, Toshia; Baird, Benjamin; Gray, Tristan S.; Ellern, Arkady; Miller, Gordon J.; Winter, Arthur H.; et al

    2016-04-28

    The reaction of CoCl2·THF and thallium tris(4,4-dimethyl-2-oxazolinyl)phenylborate (TlToM) in tetrahydrofuran (THF) provides ToMCoCl (1) in 95 % yield; however, appropriate solvents and starting materials are required to favor 1 over two other readily formed side-products, (ToM)2Co (2) and {HToM}CoCl2 (3). ESR, NMR, FTIR, and UV/Vis spectroscopies were used to distinguish these cobalt(II) products and probe their electronic and structural properties. Even after the structures indicated by these methods were confirmed by X-ray crystallography, the spectroscopic identification of trace contaminants in the material was challenging. The recognition of possible contaminants in the synthesis of ToMCoCl in combination with the paramagnetic naturemore » of these complexes provided impetus for the utilization of X-ray powder diffraction to measure the purity of the ToMCoCl bulk sample. Furthermore, the X-ray powder diffraction results provide support for the bulk-phase purity of ToMCoCl in preparations that avoid 2 and 3. Thus, 1 is a precursor for new [tris(oxazolinyl)borato]cobalt chemistry, as exemplified by its reactions with KOtBu and NaOAc to give ToMCoOtBu (4) and ToMCoOAc (5), respectively. Compound 5 is a catalyst for the oxidation of cyclohexane with meta-chloroperoxybenzoic acid (mCPBA), and the rate constants and selectivity for cyclohexanol versus cyclohexanone and ϵ-caprolactone were assessed.« less

  16. Transmural Catalysis- High Efficiency Catalyst Systems for NOx Adsorbers and SCR

    Broader source: Energy.gov [DOE]

    Presentation given at DEER 2006, August 20-24, 2006, Detroit, Michigan. Sponsored by the U.S. DOE's EERE FreedomCar and Fuel Partnership and 21st Century Truck Programs.

  17. Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Petrie, Jonathan R.; Cooper, Valentino R.; Freeland, John W.; Meyer, Tricia L.; Zhang, Zhiyong; Lutterman, Daniel A.; Lee, Ho Nyung

    2016-02-11

    Strain is known to greatly influence low-temperature oxygen electrocatalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and metal-air batteries. Still, its catalytic impact on transition-metal oxide thin films, such as perovskites, is not widely understood. Here, we epitaxially strain the conducting perovskite LaNiO3 to systematically determine its influence on both the oxygen reduction and oxygen evolution reaction. Uniquely, we found that compressive strain could significantly enhance both reactions, yielding a bifunctional catalyst that surpasses the performance of noble metals such as Pt. We attribute the improved bifunctionality to strain-induced splitting of themore » eg orbitals, which can customize orbital asymmetry at the surface. Lastly, analogous to strain-induced shifts in the d-band center of noble metals relative to the Fermi level, such splitting can dramatically affect catalytic activity in this perovskite and other potentially more active oxides.« less

  18. Plasma Catalysis for NOx Reduction from Light-Duty Diesel Vehicles

    SciTech Connect (OSTI)

    2005-12-15

    On behalf of the Department of Energy's Office of FreedomCAR and Vehicle Technologies, we are pleased to introduce the Fiscal Year (FY) 2004 Annual Progress Report for the Advanced Combustion Engine R&D Sub-Program. The mission of the FreedomCAR and Vehicle Technologies Program is to develop more energy efficient and environmentally friendly highway transportation technologies that enable Americans to use less petroleum for their vehicles. The Advanced Combustion Engine R&D Sub-Program supports this mission by removing the critical technical barriers to commercialization of advanced internal combustion engines for light-, medium-, and heavy-duty highway vehicles that meet future Federal and state emissions regulations. The primary objective of the Advanced Combustion Engine R&D Sub-Program is to improve the brake thermal efficiency of internal combustion engines from 30 to 45 percent for light-duty applications by 2010; and 40 to 55 percent for heavy-duty applications by 2012; while meeting cost, durability, and emissions constraints. R&D activities include work on combustion technologies that increase efficiency and minimize in-cylinder formation of emissions, as well as aftertreatment technologies that further reduce exhaust emissions. Work is also being conducted on ways to reduce parasitic and heat transfer losses through the development and application of thermoelectrics and turbochargers that include electricity generating capability, and conversion of mechanically driven engine components to be driven via electric motors. This introduction serves to outline the nature, current progress, and future directions of the Advanced Combustion Engine R&D Sub-Program. The research activities of this Sub-Program are planned in conjunction with the FreedomCAR Partnership and the 21st Century Truck Partnership and are carried out in collaboration with industry, national laboratories, and universities. Because of the importance of clean fuels in achieving low emissions, R&D activities are closely coordinated with the relevant activities of the Fuel Technologies Sub-Program, also within the Office of FreedomCAR and Vehicle Technologies. Research is also being undertaken on hydrogen-fueled internal combustion engines to provide an interim hydrogen-based powertrain technology that promotes the longer-range FreedomCAR Partnership goal of transitioning to a hydrogen-fueled transportation system. Hydrogen engine technologies being developed have the potential to provide diesel-like engine efficiencies with near-zero emissions.

  19. Biochemical Conversion: Using Enzymes, Microbes, and Catalysis to Make Fuels and Chemicals

    SciTech Connect (OSTI)

    2013-07-26

    This fact sheet describes the Bioenergy Technologies Office's biochemical conversion work and processes. BETO conducts collaborative research, development, and demonstration projects to improve several processing routes for the conversion of cellulosic biomass.

  20. Superacid catalysis of light hydrocarbon conversion. Final report, August 26, 1993--August 26, 1996

    SciTech Connect (OSTI)

    Gates, B.C.

    1996-12-31

    Motivated by the goal of finding improved catalysts for low- temperature conversion of light alkanes into fuel components or precursors of fuel components, the researchers have investigated sulfated zirconia and promoted sulfated zirconia for conversion of butane, propane, and ethane. Catalyst performance data for sulfated zirconia promoted with iron and manganese show that it is the most active noncorrosive, nonhalide catalyst known for n-butane isomerization, and it is an excellent candidate catalyst for new low- temperature n-butane isomerization processes to make isobutane, which can be converted by established technology into methyl t-butyl ether (MTBE). Various transition metals have been found to work as promoters of sulfated zirconia for n-butane isomerization. The combination of iron and manganese is the best known combination of promoters yet discovered. The iron- and manganese-promoted sulfated zirconia is also a catalyst for conversion of propane and of ethane. Ethane is converted into ethylene and butanes in the presence of the iron- and manganese-promoted sulfated zirconia; propane is also converted into butane, among other products. However, the activities of the catalyst for these reactions are orders of magnitude less than the activity for n-butane conversion, and there is no evidence that the catalyst would be of practical value for conversion of alkanes lighter than butane. The product distribution data for ethane and propane conversion provide new insights into the nature of the catalyst and its acidity. These data suggest the involvement of Olah superacid chemistry, whereby the catalyst protonates the alkane itself, giving carbonium ions (as transition states). The mechanism of protonation of the alkane may also pertain to the conversion of butane, but there is good evidence that the butane conversion also proceeds via alkene intermediates by conventional mechanisms of carbenium ion formation and rearrangement.

  1. The effect of host structure on the selectivity and mechanism of supramolecular catalysis of Prins cyclizations

    SciTech Connect (OSTI)

    Hart-Cooper, William M.; Zhao, Chen; Triano, Rebecca M.; Yaghoubi, Parastou; Ozores, Haxel Lionel; Burford, Kristen N.; Toste, F. Dean; Bergman, Robert G.; Raymond, Kenneth N.

    2014-11-28

    The effect of host structure on the selectivity and mechanism of intramolecular Prins reactions is evaluated using K12Ga4L6 tetrahedral catalysts. The host structure was varied by modifying the structure of the chelating moieties and the size of the aromatic spacers. While variation in chelator substituents was generally observed to affect changes in rate but not selectivity, changing the host spacer afforded differences in efficiency and product diastereoselectivity. An extremely high number of turnovers (up to 840) was observed. Maximum rate accelerations were measured to be on the order of 105, which numbers among the largest magnitudes of transition state stabilization measured with a synthetic host-catalyst. Host/guest size effects were observed to play an important role in host-mediated enantioselectivity.

  2. Technology development for iron Fischer-Tropsch catalysis. [Pretreatment of catalyst in carbon monoxide

    SciTech Connect (OSTI)

    Not Available

    1991-01-01

    The present study shows that activation of a high surface area Fe{sub 2}O{sub 3} catalyst in CO in a (CSTR), continuously stirred tank reactor using tetralin as solvent results in an activated that is three times of material that is activated in H{sub 2} or directly in the syngas.

  3. Dynamic nuclear polarization solid-state NMR in heterogeneous catalysis research

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kobayashi, Takeshi; Perras, Frédéric A.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

    2015-10-20

    In this study, a revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2–3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound.

  4. Iron(II) catalysis in oxidation of hydrocarbons with ozone in acetonitrile

    SciTech Connect (OSTI)

    Bataineh, Hajem; Pestovsky, Oleg; Bakac, Andreja

    2015-02-11

    Oxidation of alcohols, ethers, and sulfoxides by ozone in acetonitrile is catalyzed by submillimolar concentrations of Fe(CH3CN)62+. The catalyst provides both rate acceleration and greater selectivity toward the less oxidized products. For example, Fe(CH3CN)62+-catalyzed oxidation of benzyl alcohol yields benzaldehyde almost exclusively (>95%), whereas the uncatalyzed reaction generates a 1:1 mixture of benzaldehyde and benzoic acid. Similarly, aliphatic alcohols are oxidized to aldehydes/ketones, cyclobutanol to cyclobutanone, and diethyl ether to a 1:1 mixture of ethanol and acetaldehyde. The kinetics of oxidation of alcohols and diethyl ether are first-order in [Fe(CH3CN)62+] and [O3] and independent of [substrate] at concentrations greater than ~5 mM. In this regime, the rate constant for all of the alcohols is approximately the same, kcat = (8 ± 1) × 104 M–1 s–1, and that for (C2H5)2O is (5 ± 0.5) × 104 M–1 s–1. In the absence of substrate, Fe(CH3CN)62+ reacts with O3 with kFe = (9.3 ± 0.3) × 104 M–1 s–1. The similarity between the rate constants kFe and kcat strongly argues for Fe(CH3CN)62+/O3 reaction as rate-determining in catalytic oxidation. The active oxidant produced in Fe(CH3CN)62+/O3 reaction is suggested to be an Fe(IV) species in analogy with a related intermediate in aqueous solutions. As a result, this assignment is supported by the similarity in kinetic isotope effects and relative reactivities of the two species toward substrates.

  5. The effect of host structure on the selectivity and mechanism of supramolecular catalysis of Prins cyclizations

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hart-Cooper, William M.; Zhao, Chen; Triano, Rebecca M.; Yaghoubi, Parastou; Ozores, Haxel Lionel; Burford, Kristen N.; Toste, F. Dean; Bergman, Robert G.; Raymond, Kenneth N.

    2014-11-28

    The effect of host structure on the selectivity and mechanism of intramolecular Prins reactions is evaluated using K12Ga4L6 tetrahedral catalysts. The host structure was varied by modifying the structure of the chelating moieties and the size of the aromatic spacers. While variation in chelator substituents was generally observed to affect changes in rate but not selectivity, changing the host spacer afforded differences in efficiency and product diastereoselectivity. An extremely high number of turnovers (up to 840) was observed. Maximum rate accelerations were measured to be on the order of 105, which numbers among the largest magnitudes of transition state stabilizationmore » measured with a synthetic host-catalyst. Host/guest size effects were observed to play an important role in host-mediated enantioselectivity.« less

  6. Pre-Competitive Catalysis Research: Fundamental Sulfation/Desulfation Studies of Lean NOx Traps

    Broader source: Energy.gov [DOE]

    2010 DOE Vehicle Technologies and Hydrogen Programs Annual Merit Review and Peer Evaluation Meeting, June 7-11, 2010 -- Washington D.C.

  7. Using Fermentation and Catalysis to Make Fuels and Products: Biochemical Conversion

    SciTech Connect (OSTI)

    2010-09-01

    Information about the Biomass Program's collaborative projects to improve processing routes for biochemical conversion, which entails breaking down biomass to make the carbohydrates available for conversion into sugars.

  8. Effects of temperature on desiccant catalysis of refrigerant and lubricant decomposition. Final report

    SciTech Connect (OSTI)

    Rohatgi, N.D.T.

    1998-06-01

    Accelerated aging at high temperatures (149 C) for short aging times (28 days) is effective in screening the compatibility of different materials in refrigeration systems. However, in actual applications temperatures are usually lower and operating times much longer. Therefore plots to allow for interpolation or extrapolation of experimental data to actual operating conditions are needed. In the current study, aging of refrigerant/lubricant/desiccant/metal systems was conducted at five different temperatures, and for each temperature at four different aging times. The data collected from this study provided plots relating refrigerant or lubricant decomposition to aging time, aging temperature, and type of desiccant, which can be used for interpolation or extrapolation.

  9. Progress on Acidic Zirconia Mixed Oxides for Efficient NH3-SCR Catalysis

    Broader source: Energy.gov [DOE]

    Details progress on non-zeolitic zirconia-based mixed oxides as promising new SCR catalyst materials and results of engine bench testing of full-size SCR prototype confirms Details progress on non-zeolitic zirconia-based mixed oxides as promising new SCR catalyst materials and results of engine bench testing of full-size SCR prototype confirms potential for formulation of Euro 6 SCR catalysts

  10. CATALYSIS SCIENCE INITIATIVE: From First Principles Design to Realization of Bimetallic Catalysts for Enhanced Selectivity

    SciTech Connect (OSTI)

    MAVRIKAKIS, MANOS DUMESIC, JAMES A.

    2007-05-03

    In this project, we have integrated state-of-the-art Density Functional Theory (DFT) models of heterogeneous catalytic processes with high-throughput screening of bimetallic catalytic candidates for important industrial problems. We have studied a new class of alloys characterized by a surface composition different from the bulk composition, and investigated their stability and activity for the water-gas shift reaction and the oxygen reduction reaction. The former reaction is an essential part of hydrogen production; the latter is the rate-limiting step in low temperature H2 fuel cells. We have identified alloys that have remarkable stability and activity, while having a much lower material cost for both of these reactions. Using this knowledge of bimetallic interactions, we have also made progress in the industrially relevant areas of carbohydrate reforming and conversion of biomass to liquid alkanes. One aspect of this work is the conversion of glycerol (a byproduct of biodiesel production) to synthesis gas. We have developed a bifunctional supported Pt catalyst that can cleave the carbon-carbon bond while also performing the water-gas shift reaction, which allows us to better control the H2:CO ratio. Knowledge gained from the theoretical metal-metal interactions was used to develop bimetallic catalysts that perform this reaction at low temperature, allowing for an efficient coupling of this endothermic reaction with other reactions, such as Fischer-Tropsch or methanol synthesis. In our work on liquid alkane production from biomass, we have studied deactivation and selectivity in these areas as a function of metal-support interactions and reaction conditions, with an emphasis on the bifunctionality of the catalysts studied. We have identified a stable, active catalyst for this process, where the selectivity and yield can be controlled by the reaction conditions. While complete rational design of catalysts is still elusive, this work demonstrates the power of combining the insights gained from theoretical models and the work of experiments to develop new catalysts for current and future industrial challenges.

  11. A microreactor array for spatially resolved measurement of catalytic activity for high-throughput catalysis science

    SciTech Connect (OSTI)

    Kondratyuk, Petro; Gumuslu, Gamze; Shukla, Shantanu; Miller, James B; Morreale, Bryan D; Gellman, Andrew J

    2013-04-01

    We describe a 100 channel microreactor array capable of spatially resolved measurement of catalytic activity across the surface of a flat substrate. When used in conjunction with a composition spread alloy film (CSAF, e.g. Pd{sub x}Cu{sub y}Au{sub 1-x-y}) across which component concentrations vary smoothly, such measurements permit high-throughput analysis of catalytic activity and selectivity as a function of catalyst composition. In the reported implementation, the system achieves spatial resolution of 1 mm{sup 2} over a 10×10 mm{sup 2} area. During operation, the reactant gases are delivered at constant flow rate to 100 points of differing composition on the CSAF surface by means of a 100-channel microfluidic device. After coming into contact with the CSAF catalyst surface, the product gas mixture from each of the 100 points is withdrawn separately through a set of 100 isolated channels for analysis using a mass spectrometer. We demonstrate the operation of the device on a Pd{sub x}Cu{sub y}Au{sub 1-x-y} CSAF catalyzing the H{sub 2}-D{sub 2} exchange reaction at 333 K. In essentially a single experiment, we measured the catalytic activity over a broad swathe of concentrations from the ternary composition space of the Pd{sub x}Cu{sub y}Au{sub 1-x-y} alloy.

  12. Tandem catalysis by palladium nanoclusters encapsulated in metal–organic frameworks

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Xinle; Guo, Zhiyong; Xiao, Chaoxian; Goh, Tian Wei; Tesfagaber, Daniel; Huang, Wenyu

    2014-08-25

    A bifunctional Zr-MOF catalyst containing palladium nanoclusters (NCs) has been developed. The formation of Pd NCs was confirmed by transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS). Combining the oxidation activity of Pd NCs and the acetalization activity of the Lewis acid sites in UiO-66-NH2, this catalyst (Pd@UiO-66-NH2) exhibits excellent catalytic activity and selectivity in a one-pot tandem oxidation-acetalization reaction. This catalyst shows 99.9% selectivity to benzaldehyde ethylene acetal in the tandem reaction of benzyl alcohol and ethylene glycol at 99.9% conversion of benzyl alcohol. We also examined various substituted benzyl alcohols and found that alcohols withmore » electron-donating groups showed better conversion and selectivity compared to those with electron-withdrawing groups. As a result, we further proved that there was no leaching of active catalytic species during the reaction and the catalyst can be recycled at least five times without significant deactivation.« less

  13. Iron(II) catalysis in oxidation of hydrocarbons with ozone in acetonitrile

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bataineh, Hajem; Pestovsky, Oleg; Bakac, Andreja

    2015-02-11

    Oxidation of alcohols, ethers, and sulfoxides by ozone in acetonitrile is catalyzed by submillimolar concentrations of Fe(CH3CN)62+. The catalyst provides both rate acceleration and greater selectivity toward the less oxidized products. For example, Fe(CH3CN)62+-catalyzed oxidation of benzyl alcohol yields benzaldehyde almost exclusively (>95%), whereas the uncatalyzed reaction generates a 1:1 mixture of benzaldehyde and benzoic acid. Similarly, aliphatic alcohols are oxidized to aldehydes/ketones, cyclobutanol to cyclobutanone, and diethyl ether to a 1:1 mixture of ethanol and acetaldehyde. The kinetics of oxidation of alcohols and diethyl ether are first-order in [Fe(CH3CN)62+] and [O3] and independent of [substrate] at concentrations greater thanmore » ~5 mM. In this regime, the rate constant for all of the alcohols is approximately the same, kcat = (8 ± 1) × 104 M–1 s–1, and that for (C2H5)2O is (5 ± 0.5) × 104 M–1 s–1. In the absence of substrate, Fe(CH3CN)62+ reacts with O3 with kFe = (9.3 ± 0.3) × 104 M–1 s–1. The similarity between the rate constants kFe and kcat strongly argues for Fe(CH3CN)62+/O3 reaction as rate-determining in catalytic oxidation. The active oxidant produced in Fe(CH3CN)62+/O3 reaction is suggested to be an Fe(IV) species in analogy with a related intermediate in aqueous solutions. As a result, this assignment is supported by the similarity in kinetic isotope effects and relative reactivities of the two species toward substrates.« less

  14. Large-Scale First-Principles Molecular Dynamics Simulations with Electrostatic Embedding: Application to Acetylcholinesterase Catalysis

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Fattebert, Jean-Luc; Lau, Edmond Y.; Bennion, Brian J.; Huang, Patrick; Lightstone, Felice C.

    2015-10-22

    Enzymes are complicated solvated systems that typically require many atoms to simulate their function with any degree of accuracy. We have recently developed numerical techniques for large scale First-Principles molecular dynamics simulations and applied them to study the enzymatic reaction catalyzed by acetylcholinesterase. We carried out Density functional theory calculations for a quantum mechanical (QM) sub- system consisting of 612 atoms with an O(N) complexity finite-difference approach. The QM sub-system is embedded inside an external potential field representing the electrostatic effect due to the environment. We obtained finite temperature sampling by First-Principles molecular dynamics for the acylation reaction of acetylcholinemore » catalyzed by acetylcholinesterase. Our calculations shows two energies barriers along the reaction coordinate for the enzyme catalyzed acylation of acetylcholine. In conclusion, the second barrier (8.5 kcal/mole) is rate-limiting for the acylation reaction and in good agreement with experiment.« less

  15. Functionalized Nanoparticles and Surfaces for Controlled Chemical Catalysis and Effective Light Harvesting

    SciTech Connect (OSTI)

    Marye Anne Fox, James K. Whitesell

    2012-11-02

    We have prepared a range of such arrays as key components for biotechnology and photonic applications. These involve self-assembled arrays of increasing complexity with three-dimensionally disposed multilayer interactions. These arrays also include dendrimers as the distinguishing structural building blocks. These photoactive integrated systems have a regular, highly-branched, three-dimensional architecture. Structural modifications of these units include variation of the core, bridging layers, and terminal groups. These modifications result in a large array of dendritic molecules with potential applications for light harvesting.

  16. The Catalysis Center for Energy Innovation is an Energy Frontier Research Center

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    February 17, 2016 12:30 PM  322 ISE Lab Susannah Scott Mellichamp Professor of Sustainable Catalytic Processing Department of Chemical Engineering Department of Chemistry & Biochemistry University of California, Santa Barbara Biography: Scott received her B.Sc. in Chemistry from the University of Alberta (Canada) in 1987, and her Ph.D. in Inorganic Chemistry from Iowa State University in 1991, where she worked with J. Espenson and A. Bakac on the activation of O2 and organic oxidation

  17. Tandem catalysis by palladium nanoclusters encapsulated in metal–organic frameworks

    SciTech Connect (OSTI)

    Li, Xinle; Guo, Zhiyong; Xiao, Chaoxian; Goh, Tian Wei; Tesfagaber, Daniel; Huang, Wenyu

    2014-08-25

    A bifunctional Zr-MOF catalyst containing palladium nanoclusters (NCs) has been developed. The formation of Pd NCs was confirmed by transmission electron microscopy (TEM) and extended X-ray absorption fine structure (EXAFS). Combining the oxidation activity of Pd NCs and the acetalization activity of the Lewis acid sites in UiO-66-NH2, this catalyst (Pd@UiO-66-NH2) exhibits excellent catalytic activity and selectivity in a one-pot tandem oxidation-acetalization reaction. This catalyst shows 99.9% selectivity to benzaldehyde ethylene acetal in the tandem reaction of benzyl alcohol and ethylene glycol at 99.9% conversion of benzyl alcohol. We also examined various substituted benzyl alcohols and found that alcohols with electron-donating groups showed better conversion and selectivity compared to those with electron-withdrawing groups. As a result, we further proved that there was no leaching of active catalytic species during the reaction and the catalyst can be recycled at least five times without significant deactivation.

  18. This research was supported as part of the Catalysis Center for...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    of new materials leading to more energy efficient and benign chemical transformations. A critical reaction in utilization of the most abundant biomass ingredient, cellulose,...

  19. This research was supported as part of the Catalysis Center for...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    wood, agricultural wastes, and energy crops) directly into aromatics and olefins with zeolite catalysts in a fluidized bed reactor in a process called catalytic fast pyrolysis. ...

  20. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for ... Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for ...

  1. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for ... Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for ...

  2. Direct Observation of Photoinduced Charge Separation in Ruthenium Complex/Ni(OH)2 nanoparticle Hybrid

    SciTech Connect (OSTI)

    Tang, Yu; Pattengale, Brian A.; Ludwig, John M.; Atifi, Abderrahman; Zinovev, Alexander V.; Dong, Bin; Kong, Qingyu; Zuo, Xiaobing; Zhang, Xiaoyi; Huang, Jier

    2015-12-17

    Ni(OH)2 have emerged as important functional materials for solar fuel conversion because of their potential as cost-effective bifunctional catalysts for both hydrogen and oxygen evolution reactions. However, their roles as photocatalysts in the photoinduced charge separation (CS) reactions remain unexplored. In this paper, we investigate the CS dynamics of a newly designed hybrid catalyst by integrating a Ru complex with Ni(OH)2 nanoparticles (NPs). Using time resolved X-ray absorption spectroscopy (XTA), we directly observed the formation of the reduced Ni metal site (~60 ps), unambiguously demonstrating CS process in the hybrid through ultrafast electron transfer from Ru complex to Ni(OH)2 NPs. Compared to the ultrafast CS process, the charge recombination in the hybrid is ultraslow (>>50 ns). These results not only suggest the possibility of developing Ni(OH)2 as solar fuel catalysts, but also represent the first time direct observation of efficient CS in a hybrid catalyst using XTA.

  3. Isotopic separation of D.sub.2 O from H.sub.2 O using ruthenium adsorbent

    DOE Patents [OSTI]

    Thiel, Patricia A.

    1990-04-10

    A method of enrichment of D.sub.2 O in solutions of D.sub.2 O in H.sub.2 O by contacting said solutions in the steam phase with hexagonal crystalline to produce enriched D.sub.2 O. The passages may be repeated to achieve a desired amount of D.sub.2 O.

  4. Ruthenium trisbipyridine as a candidate for gas-phase spectroscopic studies in a Fourier transform mass spectrometer

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Scott, Jill R.; Ham, Jason E.; Durham, Bill; Tremblay, Paul L.

    2004-01-01

    Metal polypyridines are excellent candidates for gas-phase optical experiments where their intrinsic properties can be studied without complications due to the presence of solvent. The fluorescence lifetimes of [Ru(bpy) 3 ] 1+ trapped in an optical detection cell within a Fourier transform mass spectrometer were obtained using matrix-assisted laser desorption/ionization to generate the ions with either 2,5-dihydroxybenzoic acid (DHB) or sinapinic acid (SA) as matrix. All transients acquired, whether using DHB or SA for ion generation, were best described as approximately exponential decays. The rate constant for transients derived using DHB as matrix was 4×10 7 s −1 ,more » while the rate constant using SA was 1×10 7 s −1 . Some suggestions of multiple exponential decay were evident although limited by the quality of the signals. Photodissociation experiments revealed that [Ru(bpy) 3 ] 1+ generated using DHB can decompose to [Ru(bpy) 2 ] 1+ , whereas ions generated using SA showed no decomposition. Comparison of the mass spectra with the fluorescence lifetimes illustrates the promise of incorporating optical detection with trapped ion mass spectrometry techniques.« less

  5. Transition Metal Catalyzed Hydroarylation of Multiple Bonds: Exploration of Second Generation Ruthenium Catalysts and Extension to Copper Systems

    SciTech Connect (OSTI)

    T. Brent Gunnoe

    2011-02-17

    Catalysts provide foundational technology for the development of new materials and can enhance the efficiency of routes to known materials. New catalyst technologies offer the possibility of reducing energy and raw material consumption as well as enabling chemical processes with a lower environmental impact. The rising demand and expense of fossil resources has strained national and global economies and has increased the importance of accessing more efficient catalytic processes for the conversion of hydrocarbons to useful products. The goals of the research are to develop and understand single-site homogeneous catalysts for the conversion of readily available hydrocarbons into useful materials. A detailed understanding of these catalytic reactions could lead to the development of catalysts with improved activity, longevity and selectivity. Such transformations could reduce the environmental impact of hydrocarbon functionalization, conserve energy and valuable fossil resources and provide new technologies for the production of liquid fuels. This project is a collaborative effort that incorporates both experimental and computational studies to understand the details of transition metal catalyzed C-H activation and C-C bond forming reactions with olefins. Accomplishments of the current funding period include: (1) We have completed and published studies of C-H activation and catalytic olefin hydroarylation by TpRu{l_brace}P(pyr){sub 3}{r_brace}(NCMe)R (pyr = N-pyrrolyl) complexes. While these systems efficiently initiate stoichiometric benzene C-H activation, catalytic olefin hydroarylation is hindered by inhibition of olefin coordination, which is a result of the steric bulk of the P(pyr){sub 3} ligand. (2) We have extended our studies of catalytic olefin hydroarylation by TpRu(L)(NCMe)Ph systems to L = P(OCH{sub 2}){sub 3}CEt. Thus, we have now completed detailed mechanistic studies of four systems with L = CO, PMe{sub 3}, P(pyr){sub 3} and P(OCH{sub 2}){sub 3}CEt, which has provided a comprehensive understanding of the impact of steric and electronic parameters of 'L' on the catalytic hydroarylation of olefins. (3) We have completed and published a detailed mechanistic study of stoichiometric aromatic C-H activation by TpRu(L)(NCMe)Ph (L = CO or PMe{sub 3}). These efforts have probed the impact of functionality para to the site of C-H activation for benzene substrates and have allowed us to develop a detailed model of the transition state for the C-H activation process. These results have led us to conclude that the C-H bond cleavage occurs by a {sigma}-bond metathesis process in which the C-H transfer is best viewed as an intramolecular proton transfer. (4) We have completed studies of Ru complexes possessing the N-heterocyclic carbene IMes (IMes = 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene). One of these systems is a unique four-coordinate Ru(II) complex that catalyzes the oxidative hydrophenylation of ethylene (in low yields) to produce styrene and ethane (utilizing ethylene as the hydrogen acceptor) as well as the hydrogenation of olefins, aldehydes and ketones. These results provide a map for the preparation of catalysts that are selective for oxidative olefin hydroarylation. (5) The ability of TpRu(PMe{sub 3})(NCMe)R systems to activate sp{sup 3} C-H bonds has been demonstrated including extension to subsequent C-C bond forming steps. These results open the door to the development of catalysts for the functionalization of more inert C-H bonds. (6) We have discovered that Pt(II) complexes supported by simple nitrogen-based ligands serve as catalysts for the hydroarylation of olefins. Given the extensive studies of Pt-based catalytic C-H activation, we believe these results will provide an entry point into an array of possible catalysts for hydrocarbon functionalization.

  6. Mechanism of water oxidation by [Ru(bda)(L)₂]: The return of the "blue dimer"

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Concepcion, Javier J.; Zhong, Diane K.; Szalda, David J.; Muckerman, James T.; Fujita, Etsuko

    2015-02-05

    We describe here a combined solution-surface-DFT calculations study for complexes of the type [Ru(bda)(L)₂] including X-ray structure of intermediates, their reactivity, as well as pH-dependent electrochemistry and spectroelectrochemistry. These studies shed light on the mechanism of water oxidation by [Ru(bda)(L)₂], revealing key features unavailable from solution studies with sacrificial oxidants.

  7. Dimeric fluorescent energy transfer dyes comprising asymmetric cyanine azole-indolenine chromophores

    DOE Patents [OSTI]

    Glazer, Alexander N.; Benson, Scott C.

    1996-01-01

    Novel fluorescent DNA-staining dyes are provided combining asymmetric cyanine azole-indolenine dyes, which provide for strong DNA affinity, large Stokes shifts and emission in the red region of the spectrum. The dyes find particular application in gel electrophoresis and for labels which may be bound to a variety of compositions in a variety of contexts.

  8. Dimeric fluorescent energy transfer dyes comprising asymmetric cyanine azole-indolenine chromophores

    DOE Patents [OSTI]

    Glazer, Alexander N.; Benson, Scott C.

    1998-01-01

    Novel fluorescent heterodimeric DNA-staining energy transfer dyes are provided combining asymmetric cyanine azole-indolenine dyes, which provide for strong DNA affinity, large Stokes shifts and emission in the red region of the spectrum. The dyes find particular application in gel electrophoresis and for labels which may be bound to a variety of compositions in a variety of contexts. Kits and individual compounds are provided, where the kits find use for simultaneous detection of a variety of moieties, particularly using a single narrow wavelength irradiation source. The individual compounds are characterized by high donor quenching and high affinity to dsDNA as a result of optimizing the length of the linking group separating the two chromophores.

  9. Circuit model optimization of a nano split ring resonator dimer antenna operating in infrared spectral range

    SciTech Connect (OSTI)

    Gneiding, N.; Zhuromskyy, O.; Peschel, U.; Shamonina, E.

    2014-10-28

    Metamaterials are comprised of metallic structures with a strong response to incident electromagnetic radiation, like, for example, split ring resonators. The interaction of resonator ensembles with electromagnetic waves can be simulated with finite difference or finite elements algorithms, however, above a certain ensemble size simulations become inadmissibly time or memory consuming. Alternatively a circuit description of metamaterials, a well developed modelling tool at radio and microwave frequencies, allows to significantly increase the simulated ensemble size. This approach can be extended to the IR spectral range with an appropriate set of circuit element parameters accounting for physical effects such as electron inertia and finite conductivity. The model is verified by comparing the coupling coefficients with the ones obtained from the full wave numerical simulations, and used to optimize the nano-antenna design with improved radiation characteristics.

  10. Metal oxide films on metal

    DOE Patents [OSTI]

    Wu, Xin D. (Los Alamos, NM); Tiwari, Prabhat (Los Alamos, NM)

    1995-01-01

    A structure including a thin film of a conductive alkaline earth metal oxide selected from the group consisting of strontium ruthenium trioxide, calcium ruthenium trioxide, barium ruthenium trioxide, lanthanum-strontium cobalt oxide or mixed alkaline earth ruthenium trioxides thereof upon a thin film of a noble metal such as platinum is provided.

  11. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis ... (4) catalysis (homogeneous), solar (photovoltaic), bio-inspired, charge transport, ...

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    Office of Scientific and Technical Information (OSTI)

    ... Filter Results Filter by Subject catalysis (heterogeneous), solar (photovoltaic), phonons, ... catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy ...

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  14. Multiferroicity of Carbon-Based Charge-Transfer Magnets (Journal...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Energy Frontier Research Centers (EFRC); Argonne-Northwestern Solar Energy ... Subject: catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar ...

  15. A bioinspired redox relay that mimics radical interactions of...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, ...

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    catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, charge ...

  17. Mimicking the electron transfer chain in photosystem II with...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, ...

  18. Optical and electrochemical properties of hydrogen-bondedphenol...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, hydrogen and fuel cells, electrodes - solar, ...

  19. Nanoscale Imaging of Lithium Ion Distribution During In Situ...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (homogeneous), catalysis (heterogeneous), energy storage (including batteries and capacitors), hydrogen and fuel cells, defects, charge transport, membrane, ...

  20. In Situ Electron Energy-Loss Spectroscopy in Liquids (Journal...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (homogeneous), catalysis (heterogeneous), energy storage (including batteries and capacitors), hydrogen and fuel cells, defects, charge transport, membrane, ...

  1. Low-temperature superacid catalysis: Reactions of n-butane catalyzed by iron- and manganese-promoted sulfated zirconia

    SciTech Connect (OSTI)

    Cheung, T.K.; D`Itri, J.L.; Gates, B.C.

    1995-02-01

    Environmental concerns are leading to the replacement of aromatic hydrocarbons in gasoline with high-octane-number branched paraffins and oxygenated compounds such as methyl t-butyl ether, which is produced from methanol and isobutylene. The latter can be formed from n-butane by isomerization followed by dehydrogenation. To meet the need for improved catalysts for isomerization of n-butane and other paraffins, researchers identified solid acids that are noncorrosive and active at low temperatures. Sulfated zirconia catalyzes the isomerization of n-butane even at 25{degrees}C, and the addition of Fe and Mn promoters increases its activity by three orders of magnitude. Little is known about this new catalyst. Here the authors provide evidence of its performance for n-butane conversion, demonstrating that isomerization is accompanied by disproportionation and other, less well understood, acid-catalyzed reactions and undergoes rapid deactivation associated with deposition of carbonaceous material. 10 refs., 3 figs.

  2. Support shape effect in metal oxide catalysis: ceria nanoshapes supported vanadia catalysts for oxidative dehydrogenation of iso-butane

    SciTech Connect (OSTI)

    Wu, Zili; Schwartz, Viviane; Li, Meijun; Rondinone, Adam Justin; Overbury, Steven {Steve} H

    2012-01-01

    The activation energy of VOx/CeO2 catalysts in oxidative dehydrogenation of iso-butane was found dependent on the shape of ceria support: rods < octahedra, closely related to the surface oxygen vacancy formation energy and defects amount of the two ceria supports with different crystallographic surface planes.

  3. Superacid catalysis of light hydrocarbon conversion. DOE PETC fourth quarterly report, May 25, 1994--August 24, 1994

    SciTech Connect (OSTI)

    Gates, B.C.

    1995-12-31

    The primary goal of this project is to evaluate the potential value of solid superacid catalysts of the sulfated zirconia type for light hydrocarbon conversion. The key experiments include testing of the performance of such catalysts in a flow reactor fed with streams containing, for example, n-butane or propane. A solid superacid catalyst was prepared by addition of iron and manganese to sulfated zirconium hydroxide followed by calcination. The catalyst was tested for n-butane conversion in a packed-bed flow reactor at temperatures of 40 to 225{degrees}C with the reactant partial pressure in the range of 0.0025-0.01 attn. The predominant catalytic reaction was n-butane isomerization, and this was accompanied at 40{degrees}C by near stoichiometric disproportionation. The C3/C5 molar ratio was generally greater than 1, consistent with conversion of the secondary C5 products. As the temperature increased, the selectivity for isomerization decreased and that for disproportionation increased. In a typical experiment the activity of the catalyst increased for about 1 h on stream and then declined rapidly. The rate maxima as a function of time on stream were taken as a measure of the initial activity of the catalyst. For example, the approximate rate of isomerization of n-butane at the maximum was 4.3 x 10-8 mol/(g of catalyst {center_dot} s) with a feed n-butane partial pressure of 0.0025 atm at 75{degrees}C. With a feed n-butane partial pressure of 0.005 atm at 40{degrees}C and a conversion of 1 1%, the molar ratio of propane to i-butane was 0.03, and with the same feed composition at 100{degrees}C, this ratio at a conversion of 50% was 0.1. The iron- and manganese-promoted solid superacid catalyst is potentially of value for practical low-temperature paraffin isomerization accompanied by disproportionation of n-butane.

  4. Low-temperature superacid catalysis: Reactions of n - butane and propane catalyzed by iron- and manganese-promoted sulfated zirconia

    SciTech Connect (OSTI)

    Tsz-Keung, Cheung; d`Itri, J.L.; Lange, F.C.; Gates, B.C.

    1995-12-31

    The primary goal of this project is to evaluate the potential value of solid superacid catalysts of the sulfated zirconia type for light hydrocarbon conversion. The key experiments catalytic testing of the performance of such catalysts in a flow reactor fed with streams containing, for example, n-butane or propane. Fe- and Mn-promoted sulfated zirconia was used to catalyze the conversion of n-butane at atmospheric pressure, 225-450{degrees}C, and n-butane partial pressures in the range of 0.0025-0.01 atm. At temperatures <225{degrees}C, these reactions were accompanied by cracking; at temperatures >350{degrees}C, cracking and isomerization occurred. Catalyst deactivation, resulting at least in part from coke formation, was rapid. The primary cracking products were methane, ethane, ethylene, and propylene. The observation of these products along with an ethane/ethylene molar ratio of nearly 1 at 450{degrees}C is consistent with cracking occurring, at least in part, by the Haag-Dessau mechanism, whereby the strongly acidic catalyst protonates n-butane to give carbonium ions. The rate of methane formation from n-butane cracking catalyzed by Fe- and Mn-promoted sulfated zirconia at 450{degrees}C was about 3 x 10{sup -8} mol/(g of catalyst {center_dot}s). The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.

  5. Scanning Tunneling Microscopy and Theoretical Study of Water Adsorption on Fe3O4: Implications for Catalysis

    SciTech Connect (OSTI)

    Rim, Kwang T.; Eom, Daejin; Chan, Siu-Wai; Flytzani-Stephanopoulos, Maria; Flynn, George; Wen, Xiaodong; Batista, Enrique R.

    2012-10-23

    The reduced surface of a natural Hematite single crystal a-Fe2O3(0001) sample has multiple surface domains with di!erent terminations, Fe2O3(0001), FeO(111), and Fe3O4(111). The adsorption of water on this surface was investigated via Scanning Tunneling Microscopy (STM) and first-principle theoretical simulations. Water species are observed only on the Fe-terminated Fe3O4(111) surface at temperatures up to 235 K. Between 235 and 245 K we observed a change in the surface species from intact water molecules and hydroxyl groups bound to the surface to only hydroxyl groups atop the surface terminating FeIII cations. This indicates a low energy barrier for water dissociation on the surface of Fe3O4 that is supported by our theoretical computations. Our first principles simulations con"rm the identity of the surface species proposed from the STM images, finding that the most stable state of a water molecule is the dissociated one (OH + H), with OH atop surface terminating FeIII sites and H atop under-coordinated oxygen sites. Attempts to simulate reaction of the surface OH with coadsorbed CO fail because the only binding sites for CO are the surface FeIII atoms, which are blocked by the much more strongly bound OH. In order to promote this reaction we simulated a surface decorated with gold atoms. The Au adatoms are found to cap the under-coordinated oxygen sites and dosed CO is found to bind to the Au adatom. This newly created binding site for CO not only allows for coexistence of CO and OH on the surface of Fe3O4 but also provides colocation between the two species. These two factors are likely promoters of catalytic activity on Au/Fe3O4(111) surfaces.

  6. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect (OSTI)

    Enrique Iglesia; Akio Ishikawa; Manual Ojeda; Nan Yao

    2007-09-30

    A detailed study of the catalyst composition, preparation and activation protocol of Fe-based catalysts for the Fischer-Tropsch Synthesis (FTS) have been carried out in this project. We have studied the effects of different promoters on the catalytic performance of Fe-based catalysts. Specifically, we have focused on how their sequence of addition dramatically influences the performance of these materials in the Fischer-Tropsch synthesis. The resulting procedures have been optimized to improve further upon the already unprecedented rates and C{sub 5+} selectivities of the Fe-based catalysts that we have developed as part of this project. Selectivity to C{sub 5+} hydrocarbon was close to 90 % (CO{sub 2}-free basis) and CO conversion rate was about 6.7 mol h{sup -1} g-at Fe{sup -1} at 2.14 MPa, 508 K and with substoichiometric synthesis gas; these rates were larger than any reported previously for Fe-based FTS catalysts at these conditions. We also tested the stability of Fe-based catalysts during FTS reaction (10 days); as a result, the high hydrocarbon formation rates were maintained during 10 days, though the gradual deactivation was observed. Our investigation has also focused on the evaluation of Fe-based catalysts with hydrogen-poor synthesis gas streams (H{sub 2}/CO=1). We have observed that the Fe-based catalysts prepared in this project display also a high hydrocarbon synthesis rate with substoichiometric synthesis gas (H{sub 2}/CO=1) stream, which is a less desirable reactant mixture than stoichiometric synthesis gas (H{sub 2}/CO=2). We have improved the catalyst preparation protocols and achieved the highest FTS reaction rates and selectivities so far reported at the low temperatures required for selectivity and stability. Also, we have characterized the catalyst structural change and active phases formed, and their catalytic behavior during the activation process to evaluate their influences on FTS reaction. The efforts of this project led to (i) structural evolution of Fe-Zn oxide promoted with K and Cu, and (ii) evaluation of hydrocarbon and CH{sub 4} formation rates during activation procedures at various temperature and H{sub 2}/CO ratios. On the basis of the obtained results, we suggest that lower reactor temperature can be sufficient to activate catalysts and lead to the high FTS performance. In this project, we have also carried out a detailed kinetic and mechanistic study of the Fischer-Tropsch Synthesis with Fe-based catalysts. We have proposed a reaction mechanism with two CO activation pathways: unassisted and H-assisted. Both routes lead to the formation of the same surface monomers (CH{sub 2}). However, the oxygen removal mechanism is different. In the H-assisted route, oxygen is removed exclusively as water, while oxygen is rejected as carbon dioxide in the unassisted CO dissociation. The validity of the mechanism here proposed has been found to be in agreement with the experimental observation and with theoretical calculations over a Fe(110) surface. Also, we have studied the validity of the mechanism that we propose by analyzing the H{sub 2}/D{sub 2} kinetic isotope effect (r{sub H}/r{sub D}) over a conventional iron-based Fischer-Tropsch catalyst Fe-Zn-K-Cu. We have observed experimentally that the use of D{sub 2} instead of H{sub 2} leads to higher hydrocarbons formation rates (inverse kinetic isotopic effect). On the contrary, primary carbon dioxide formation is not influenced. These experimental observations can be explained by two CO activation pathways. We have also explored the catalytic performance of Co-based catalysts prepared by using inverse micelles techniques. We have studied several methods in order to terminate the silanol groups on SiO{sub 2} support including impregnation, urea homogeneous deposition-precipitation, or zirconium (IV) ethoxide titration. Although hydroxyl groups on the SiO{sub 2} surface are difficult to be stoichiometrically titrated by ZrO{sub 2}, a requirement to prevent the formation of strongly-interacting Co oxide species on SiO{sub 2}, modification of ZrO{sub 2} on SiO{sub 2} surface can improve the Co clusters dispersion leading to a marked increase in the number of accessible Co sites. Inverse micelle method allowed the synthesis of small Co clusters on SiO{sub 2}, but the required surfactant removal steps led to the re-oxidation of Co metal clusters and to the formation of difficult to reduce CoO{sub x} species.

  7. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect (OSTI)

    Akio; Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

    2006-09-30

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rates and selectivities for feedstocks consisting of synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch Synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based FT catalysts with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During the fifth reporting period, we studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influenced the performance of these materials in the Fischer-Tropsch synthesis. We also continued our studies of the kinetic behavior of these materials. Specifically, the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch Synthesis reactions led us to propose a new sequence of elementary steps on Fe and Co Fischer-Tropsch catalysts. More specifically, we were focused on the roles of hydrogen-assisted and alkali-assisted dissociation of CO in determining rates and CO{sub 2} selectivities. During this sixth reporting period, we have studied the validity of the mechanism that we propose by analyzing the H{sub 2}/D{sub 2} kinetic isotope effect (r{sub H}/r{sub D}) over a conventional iron-based Fischer-Tropsch catalyst Fe-Zn-K-Cu. We have observed experimentally that the use of D{sub 2} instead of H{sub 2} leads to higher hydrocarbons formation rates (inverse kinetic isotopic effect). On the contrary, primary carbon dioxide formation is not influenced. These experimental observations can be explained by the two CO activation pathways we propose. During this reporting period, the experimental kinetic study has been also complemented with periodic, self-consistent, DFT-GGA investigations in a parallel collaboration with the group of Manos Mavrikakis at the University of Wisconsin-Madison. These DFT calculations suggest minimal energy paths for proposed elementary steps on Fe(110) and Co(0001) surfaces. These calculations support our novel conclusions about the preferential dissociation of CO dissociation via H-assisted pathways on Fe-based catalysts. Unassisted CO dissociation also occurs and lead to the formation of CO{sub 2} as a primary oxygen scavenging mechanism after CO dissociation on Fe-based catalysts. Simulations and our experimental data show also that unassisted CO dissociation route is much less likely on Co surfaces and that hydrocarbons form exclusively via H-assisted pathways with the formation of H{sub 2}O as the sole oxygen rejection product. We have also started a study of the use of colloidal precipitation methods for the synthesis of small Fe and Co clusters using recently developed methods to explore possible further improvements in Fischer-Tropsch synthesis rates and selectivities. We have found that colloidal synthesis makes possible the preparation of small cobalt particles, although large amount of cobalt silicate species, which are difficult to reduce, are formed. The nature of the cobalt precursor and the modification of the support seem to be critical parameters in order to obtain highly dispersed and reducible Co nanoparticles.

  8. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    SciTech Connect (OSTI)

    Sawyer, Karma Rae

    2008-12-12

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  9. Technology development for iron Fischer-Tropsch catalysis. Quarterly technical progress report No. 5, October 1, 1995--December 31, 1995

    SciTech Connect (OSTI)

    Davis, B.H.

    1996-01-19

    The objective of this research project is to develop the technology for the production of physically robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry phase synthesis reactor development. The catalysts that are developed shall be suitable for testing in the Advanced Fuels Development Facility at LaPorte, Texas, to produce either low- or high-alpha product distributions. Previous work by the offeror has produced a catalyst formulation that is 1.5 times as active as the ``standard-catalyst`` developed by German workers for slurry phase synthesis. The proposed work will optimize the catalyst composition and pretreatment operation for this low-alpha catalyst. In parallel, work will be conducted to design a high-alpha iron catalyst this is suitable for slurry phase synthesis. Studies will be conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. The oxidation/reduction cycles that are anticipated to occur in large, commercial reactors will be studied at the laboratory scale. Catalyst performance will be determined for catalysts synthesized in this program for activity, selectivity and aging characteristics. The research is divided into four major topical areas: (a) catalyst preparation and characterization, (b) product characterization, (c) reactor operations, and (d) data assessment. Accomplishments to date are described.

  10. Technology development for iron Fischer-Tropsch catalysis. Quarterly technical progress report No. 6, January 1, 1996--March 31, 1996

    SciTech Connect (OSTI)

    Davis, B.H.

    1996-05-01

    The objective of this research project is to develop the technology for the production of physically robust iron-based Fischer-Tropsch catalysts that have suitable activity, selectivity and stability to be used in the slurry phase synthesis reactor development. The catalysts that are developed shall be suitable for testing in the Advanced Fuels Development Facility at LaPorte, Texas, to produce either low- or high-alpha product distributions. Previous work by the offeror has produced a catalyst formulation that is 1.5 times as active as the ``standard-catalyst`` developed by German workers for slurry phase synthesis. The proposed work will optimize the catalyst composition and pretreatment operation for this low-alpha catalyst. In parallel, work will be conducted to design a high-alpha iron catalyst that is suitable for slurry phase synthesis. Studies will be conducted to define the chemical phases present at various stages of the pretreatment and synthesis stages and to define the course of these changes. The oxidation/reduction cycles that are anticipated to occur in large, commercial reactors will be studied at the laboratory scale. Catalyst performance will be determined for catalysts synthesized in this program for activity, selectivity and aging characteristics. The research is divided into four major topical areas: (a) catalyst preparation and characterization, (b) product characterization, (c) reactor operations, and (d) data assessment. Accomplishments for this period are discussed.

  11. Technology development for iron Fischer-Tropsch catalysis. Quarterly technical progress report for period ending March 31, 1991

    SciTech Connect (OSTI)

    Not Available

    1991-12-31

    The present study shows that activation of a high surface area Fe{sub 2}O{sub 3} catalyst in CO in a (CSTR), continuously stirred tank reactor using tetralin as solvent results in an activated that is three times of material that is activated in H{sub 2} or directly in the syngas.

  12. Fabrication of Carbon-Platinum Interdigitated Array Electrodes and Their Application for Investigating Homogeneous Hydrogen Evolution Catalysis

    SciTech Connect (OSTI)

    Liu, Fei; Divan, Ralu; Parkinson, Bruce A.

    2015-06-29

    Carbon interdigitated array (IDA) electrodes have been applied to study the homogeneous hydrogen evolution electrocatalyst [Ni(PPh2NBn2)2]2+ (where PPh2NBn2 is 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane). The existence of reaction intermediates in the catalytic cycle is inferred from the electrochemical behavior of a glassy carbon disk electrodes and carbon IDA electrodes. The currents on IDA electrodes for an EC (electron transfer reaction followed by a catalytic reaction) mechanism are derived from the number of redox cycles and the contribution of non-catalytic currents. The catalytic reaction rate constant was then extracted from the IDA current equations. Applying the IDA current and kinetic equations to the electrochemical response of the [Ni(PPh2NBn2)2]2+ catalyst yielded a rate constant of 0.10 s-1 for the hydrogen evolution reaction that agrees with the literature value. The quantitative analysis of IDA cyclic voltammetry can be used as a simple and straightforward method for determining rate constants in other catalytic systems. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for DOE. Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  13. Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis

    SciTech Connect (OSTI)

    Hrdlicka, J.; Feik, C.; Carpenter, D.; Pomeroy, M.

    2008-12-01

    With oak and pine feedstocks, the Gasification of Biomass to Hydrogen project maximizes hydrogen production using the Full Stream Reformer during water-gas shift fixed-bed reactor testing. Results indicate that higher steam-to-biomass ratio and higher thermal cracker temperature yield higher hydrogen concentration. NREL's techno-economic models and analyses indicate hydrogen production from biomass may be viable at an estimated cost of $1.77/kg (current) and $1.47/kg (advanced in 2015). To verify these estimates, NREL used the Thermochemical Process Development Unit (TCPDU), an integrated system of unit operations that investigates biomass thermochemical conversion to gaseous and liquid fuels and chemicals.

  14. Fundamental Mechanistic Investigations of Silane and Chlorocarbon Addition to Low Valent Palladium Species and their Application to Catalysis

    SciTech Connect (OSTI)

    Fink, Mark J.

    2009-01-27

    The collaboration between Mark Fink (Tulane University) and R. Morris Bullock (Brookhaven National Laboratory, currently at PNL) is an effort to understand some of the fundamental processes involved in catalytic bond activations with low coordinate palladium species. The project involves the photochemical generation of reactive low-valent palladium species as transients using nanosecond laser flash photolysis and the subsequent investigation of their reactions with chloroarenes and hydrosilanes. In the case of Si-H activation of hydrosilanes, relatively long-lived sigma complexes are implicated. These complexes may be important models for C-H activation in hydrocarbons. The information obtained from these studies will help in the understanding of fundamental processes involved in a number of important catalytic reactions in the petrochemical and environmental areas.

  15. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect (OSTI)

    Enrique Iglesia

    2004-09-30

    This project explores the extension of previously discovered Fe-based catalysts with unprecedented Fischer-Tropsch synthesis rate, selectivity, and ability to convert hydrogen-poor synthesis gas streams typical of those produced from coal and biomass sources. Contract negotiations were completed on December 9, 2004. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic performance previously reported. During this second reporting period, we have prepared and tested several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. These studies established modest improvements in rates and selectivities with light hydrocarbon recycle without any observed deleterious effects, opening up the opportunities for using of recycle strategies to control temperature profiles in fixed-bed Fe-based Fischer-Tropsch synthesis reactors without any detectable kinetic detriment. In a parallel study, we examined similar effects of recycle for cobalt-based catalysts; marked selectivity improvements were observed as a result of the removal of significant transport restrictions on these catalysts. Finally, we have re-examined some previously unanalyzed data dealing with the mechanism of the Fischer-Tropsch synthesis, specifically kinetic isotope effects on the rate and selectivity of chain growth reactions on Fe-based catalysts.

  16. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect (OSTI)

    Akio Ishikawa; Manuel Ojeda; Enrique Iglesia

    2005-09-30

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rate, selectivity for feedstocks consisting of synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third reporting period, we improved the catalysts preparation method, which led to Fe-based FT catalysts with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During this fourth reporting period, we have determined the effects of different promoters on catalytic performance. More specifically, we have found that the sequence in which promoters are introduced has a marked positive impact on rates and selectivities. Cu or Ru chemical promoters should be impregnated before K to achieve higher Fischer-Tropsch synthesis rates. The catalyst prepared in this way was evaluated for 240 h, showing a high catalytic activity and stability after an initial period of time necessary for the formation of the active phases. Concurrently, we are studying optimal activation procedures, which involve the reduction and carburization of oxide precursors during the early stages of contact with synthesis gas. Activation at low temperatures (523 K), made possible by optimal introduction of Cu or Ru, leads to lower catalyst surface area than higher activation temperatures, but to higher reaction rates, because such low temperatures avoid concurrent deactivation during the reduction-carburization processes. In this reporting period, we have measured the evolution of oxide, carbide, and metal phases of the active iron components using advanced synchrotron techniques based on X-ray absorption spectroscopy. These studies have revealed that Zn inhibits the isothermal reduction and carburization of iron oxide precursors. The concurrent presence of Cu or Ru compensates for these inhibitory effects and lead to the formation of active carbide phases at the low temperatures required to avoid deactivation via carbon deposition or sintering. Finally, we have also examined the kinetic behavior of these materials, specifically the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch synthesis reactions. This has led to a rigorous rate expressions that allows the incorporation of these novel materials into larger scale reactors and to predictions of performance based on the coupling of hydrodynamic and kinetic effects ubiquitous in such reactors.

  17. Design, Synthesis, and Mechanistic Evaluation of Iron-Based Catalysis for Synthesis Gas Conversion to Fuels and Chemicals

    SciTech Connect (OSTI)

    Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

    2006-03-31

    This project extends previously discovered Fe-based catalysts to hydrogen-poor synthesis gas streams derived from coal and biomass sources. These catalysts have shown unprecedented Fischer-Tropsch synthesis rate, selectivity for feedstocks consisting of synthesis gas derived from methane. During the first reporting period, we certified a microreactor, installed required analytical equipment, and reproduced synthetic protocols and catalytic results previously reported. During the second reporting period, we prepared several Fe-based compositions for Fischer-Tropsch synthesis and tested the effects of product recycle under both subcritical and supercritical conditions. During the third and fourth reporting periods, we improved the catalysts preparation method, which led to Fe-based FT catalysts with the highest FTS reaction rates and selectivities so far reported, a finding that allowed their operation at lower temperatures and pressures with high selectivity to desired products (C{sub 5+}, olefins). During this fifth reporting period, we have studied the effects of different promoters on catalytic performance, specifically how their sequence of addition dramatically influences the performance of these materials in the Fischer-Tropsch synthesis. The resulting procedures have been optimized to improve further upon the already unprecedented rates and C{sub 5+} selectivities of the Fe-based catalysts that we have developed as part of this project. During this fifth reporting period, we have also continued our studies of optimal activation procedures, involving reduction and carburization of oxide precursors during the early stages of contact with synthesis gas. We have completed the analysis of the evolution of oxide, carbide, and metal phases of the active iron components during initial contact with synthesis gas using advanced synchrotron techniques based on X-ray absorption spectroscopy. We have confirmed that the Cu or Ru compensates for inhibitory effects of Zn, a surface area promoter. The kinetic behavior of these materials, specifically the effects of H{sub 2}, CO, and CO{sub 2} on the rates and selectivities of Fischer-Tropsch synthesis reactions has led to a new proposal for the nature of rate-determining steps on Fe and Co Fischer-Tropsch catalysts, and more specifically to the roles of hydrogen-assisted and alkali-assisted dissociation of CO in determining rates and CO{sub 2} selectivities. Finally, we have started an exploratory study of the use of colloidal precipitation methods for the synthesis of small Fe and Co clusters using recently developed methods. During this period, we have had to restrict manpower assigned to this project because some irregularities in reporting and communications have led to the interruption of funding during this period. This has led to less than optimal productivity and to significant disruptions of the technical work. These issues have also led to significant underspending of project funds during this reporting period and to our consequent request for a no-cost extension of one year, which we understand has been granted.

  18. DESIGN, SYNTHESIS, AND MECHANISTIC EVALUATION OF IRON-BASED CATALYSIS FOR SYNTHESIS GAS CONVERSION TO FUELS AND CHEMICALS

    SciTech Connect (OSTI)

    Jian Xu; Enrique Iglesia

    2004-03-31

    This project explores the extension of previously discovered Fe-based catalysts with unprecedented Fischer-Tropsch synthesis rate, selectivity, and ability to convert hydrogen-poor synthesis gas streams typical of those produced from coal and biomass sources. Contract negotiations between the U.S. Department of Energy and the University of California were completed on December 9, 2004. During this first reporting period, we have modified and certified a previously decommissioned microreactor, ordered and installed a budgeted gas chromatograph, developed and reviewed safe operating procedures and data analysis methods, and reproduced successfully previous synthetic protocols and catalytic performance of catalytic materials based on Fe-Zn-Cu-K oxide precursors synthesized using precipitation methods, drying using surface-active agents, and activated in synthesis gas within Fischer-Tropsch synthesis tubular reactors.

  19. Technology development for iron Fischer-Tropsch catalysis. Quarterly technical progress report No. 2, January 1, 1995--March 31, 1995

    SciTech Connect (OSTI)

    Davis, B.H.

    1995-05-02

    The Fischer-Tropsch synthesis has been studied over the best low-alpha catalyst developed at the CAER. A wide range of synthesis gas conversions were obtained by varying the space velocity. The experimental results show that: (1) the rate of the water gas shift reaction is lower than the rate of the Fischer-Tropsch reaction at low conversions (< 60%) whereas it closely approaches the rate of the Fischer-Tropsch synthesis at high conversions, (2) the fraction of CO converted to hydrocarbons is higher at low and intermediate conversions whereas it is smaller at high conversions, (3) the H{sub 2}/CO ratio of the product gas is equal to the H{sub 2}/CO ratio of the inlet synthesis gas at an intermediate conversion level of 67%. These findings suggest that it would be beneficial to carry out the reaction at intermediate conversions. This would result in an optimum use of CO to produce hydrocarbons rather than CO{sub 2}. High overall conversions can be obtained by either using a second reactor or recycling the product gas using a single reactor. If the intermediate conversion in a single pass is maintained at 67% there would be no need to adjust the H{sub 2}/CO ratio of the recycle stream or the feed to the second reactor as the product gas from a single pass would have the same H{sub 2}/CO ratio as the feed synthesis gas. The optimum reaction rate expression for synthesis gas conversion which has been developed for this catalyst shows that CO is strongly adsorbed on the catalyst and that the reaction products such as water and CO{sub 2} do not inhibit the reaction rate.

  20. New and improved dispersion and recovery techniques for slurry phase catalysis. Quarterly report, January-March, 1984

    SciTech Connect (OSTI)

    Tarrer, A.R.; Guin, J.A.; Curtis, C.W.; Tatarchuk, B.J.

    1984-01-01

    A mathematical model has been developed for predicting the effects of various parameters such as recycle rate, permanent and temporary deactivation rate constants on catalyst activity. The intent of this analysis is to evaluate the importance of the ease with which a catalyst can be regenerated and to identify important catalyst properties associated with regeneration. A reactor (hydrotreater)-regenerator system having equal catalyst inventory in each unit is used as a basis for modeling. A fixed amount of fresh catalyst supply and spent catalyst withdrawal are assumed to be applicable to the reactor. The analysis shows that a small percent increase in the permanent deactivation rate constant relative to total deactivation rate constant decreases the mean activity of the catalyst in the reactor significantly. In most cases, the mean activity of the catalyst increased with increasing recycle rate. The effect of regeneration rate constant on the catalyst activity was not significant compared to that of permanent deactivation rate constant. 13 references, 3 figures.

  1. Molecular beam mass spectrometer equipped with a catalytic wall reactor for in situ studies in high temperature catalysis research

    SciTech Connect (OSTI)

    Horn, R.; Ihmann, K.; Ihmann, J.; Jentoft, F.C.; Geske, M.; Taha, A.; Pelzer, K.; Schloegl, R.

    2006-05-15

    A newly developed apparatus combining a molecular beam mass spectrometer and a catalytic wall reactor is described. The setup has been developed for in situ studies of high temperature catalytic reactions (>1000 deg. C), which involve besides surface reactions also gas phase reactions in their mechanism. The goal is to identify gas phase radicals by threshold ionization. A tubular reactor, made from the catalytic material, is positioned in a vacuum chamber. Expansion of the gas through a 100 {mu}m sampling orifice in the reactor wall into differentially pumped nozzle, skimmer, and collimator chambers leads to the formation of a molecular beam. A quadrupole mass spectrometer with electron impact ion source designed for molecular beam inlet and threshold ionization measurements is used as the analyzer. The sampling time from nozzle to detector is estimated to be less than 10 ms. A detection time resolution of up to 20 ms can be reached. The temperature of the reactor is measured by pyrometry. Besides a detailed description of the setup components and the physical background of the method, this article presents measurements showing the performance of the apparatus. After deriving the shape and width of the energy spread of the ionizing electrons from measurements on N{sub 2} and He we estimated the detection limit in threshold ionization measurements using binary mixtures of CO in N{sub 2} to be in the range of several hundreds of ppm. Mass spectra and threshold ionization measurements recorded during catalytic partial oxidation of methane at 1250 deg. C on a Pt catalyst are presented. The detection of CH{sub 3}{center_dot} radicals is successfully demonstrated.

  2. Synthesis of Pt{sub 3}Sn alloy nanoparticles and their catalysis for electro-oxidation of CO and methanol.

    SciTech Connect (OSTI)

    Liu, Y.; Li, D.; Stamenkovic, V. R.; Soled, S.; Henao, J. D.; Sun, S.

    2011-11-04

    Monodisperse Pt{sub 3}Sn alloy nanoparticles (NPs) were synthesized by a controlled coreduction of Pt(II) acetylacetonate and Sn(II) acetylacetonate at 180-280 C in 1-octadecene. In the synthesis, oleylamine was used as a reducing agent, and oleylamine/oleic acid served as surfactants. The sizes of the Pt{sub 3}Sn NPs were tuned from 4 to 7 nm by controlling the metal salt injection temperatures from 180 to 240 C. These monodisperse Pt3Sn NPs were highly active for CO and methanol oxidation in 0.1 M HClO{sub 4} solutions, and their activity and stability could be further improved by a postsynthesis thermal treatment at 400 C in Ar + 5% H{sub 2} for 1 h. They are promising as a practical catalyst for CO and methanol oxidation reactions in polymer electrolyte membrane fuel cell conditions.

  3. Molecular-scale, Three-dimensional Non-Platinum Group Metal Electrodes for Catalysis of Fuel Cell Reactions

    Broader source: Energy.gov [DOE]

    Presented at the Department of Energy Fuel Cell Projects Kickoff Meeting, September 1 – October 1, 2009

  4. Mechanistic Investigation of Acid-Catalyzed Cleavage of Aryl-Ether Linkages: Implications for Lignin Depolymerization

    SciTech Connect (OSTI)

    Sturgeon, M. R.; Kim, S.; Chmely, S. C.; Foust, T. D.; Beckham, G. T.

    2013-01-01

    Carbon-oxygen bonds are the primary inter-monomer linkages lignin polymers in plant cell walls, and as such, catalyst development to cleave these linkages is of paramount importance to deconstruct biomass to its constituent monomers for the production of renewable fuels and chemicals. For many decades, acid catalysis has been used to depolymerize lignin. Lignin is a primary component of plant cell walls, which is connected primarily by aryl-ether linkages, and the mechanism of its deconstruction by acid is not well understood, likely due to its heterogeneous and complex nature compared to cellulose. For effective biomass conversion strategies, utilization of lignin is of significant relevance and as such understanding the mechanisms of catalytic lignin deconstruction to constituent monomers and oligomers is of keen interest. Here, we present a comprehensive experimental and theoretical study of the acid catalysis of a range of dimeric species exhibiting the b-O-4 linkage, the most common inter-monomer linkage in lignin. We demonstrate that the presence of a phenolic species dramatically increases the rate of cleavage in acid at 150 degrees C. Quantum mechanical calculations on dimers with the para-hydroxyl group demonstrate that this acid-catalyzed pathway differs from the nonphenolic dimmers. Importantly, this result implies that depolymerization of native lignin in the plant cell wall will proceed via an unzipping mechanism wherein b-O-4 linkages will be cleaved from the ends of the branched, polymer chains inwards toward the center of the polymer. To test this hypothesis further, we synthesized a homopolymer of b-O-4 with a phenolic hydroxyl group, and demonstrate that it is cleaved in acid from the end containing the phenolic hydroxyl group. This result suggests that genetic modifications to lignin biosynthesis pathways in plants that will enable lower severity processes to fractionate lignin for upgrading and for easier access to the carbohydrate fraction of the plant cell wall.

  5. Steric Effect for Proton, Hydrogen-Atom, andHydride Transfer Reactions with Geometric Isomers of NADH-Model Ruthenium Complexes

    SciTech Connect (OSTI)

    Fujita E.; Cohen, B.W.; Polyansky, D.E.; Achord, P.; Cabelli, D.; Muckerman, J.T.; Tanaka, K.; Thummel, R.P.; Zong, R.

    2012-01-01

    Two isomers, [Ru(1)]{sup 2+} (Ru = Ru(bpy){sub 2}, bpy = 2,2{prime}-bipyridine, 1 = 2-(pyrid-2{prime}-yl)-1-azaacridine) and [Ru(2)]{sup 2+} (2 = 3-(pyrid-2{prime}-yl)-4-azaacridine), are bio-inspired model compounds containing the nicotinamide functionality and can serve as precursors for the photogeneration of C-H hydrides for studying reactions pertinent to the photochemical reduction of metal-C{sub 1} complexes and/or carbon dioxide. While it has been shown that the structural differences between the azaacridine ligands of [Ru(1)]{sup 2+} and [Ru(2)]{sup 2+} have a significant effect on the mechanism of formation of the hydride donors, [Ru(1HH)]{sup 2+} and [Ru(2HH)]{sup 2+}, in aqueous solution, we describe the steric implications for proton, net-hydrogen-atom and net-hydride transfer reactions in this work. Protonation of [Ru(2{sup {sm_bullet}-})]{sup +} in aprotic and even protic media is slow compared to that of [Ru(1{sup {sm_bullet}-})]{sup +}. The net hydrogen-atom transfer between *[Ru(1)]{sup 2+} and hydroquinone (H{sub 2}Q) proceeds by one-step EPT, rather than stepwise electron-proton transfer. Such a reaction was not observed for *[Ru(2)]{sup 2+} because the non-coordinated N atom is not easily available for an interaction with H{sub 2}Q. Finally, the rate of the net hydride ion transfer from [Ru(1HH)]{sup 2+} to [Ph{sub 3}C]{sup +} is significantly slower than that of [Ru(2HH)]{sup 2+} owing to steric congestion at the donor site.

  6. Development of a stable cobalt-ruthenium Fischer-Tropsch catalyst. Technical progress reports No. 7 and 8, April 1, 1991--September 30, 1991

    SciTech Connect (OSTI)

    Abrevaya, H.

    1991-12-31

    The objective of this contract is to examine the relationship between catalytic properties and the function of cobalt Fischer-Tropsch catalysts and to apply this fundamental knowledge to the development of a stable cobalt-based catalyst with a low methane-plus-ethane selectivity for use in slurry reactors. An experimental cobalt catalyst 585R2723 was tested three times in the fixed-bed reactor. The objective of the tests was to identify suitable testing conditions for screening catalyst. The {alpha}-alumina was determined to be a suitable diluent medium for controlling the catalyst bed temperature close to the inlet temperature. With 13 g of catalyst and 155 g of diluent, the catalyst maximum temperature were within 2{degree}C from the inlet temperatures. As a result of this work, 210{degree}C and 21 atm were shown to result in low methane selectivity and were used as initial conditions in the catalyst screening test. Ethane, which along with methane is undesirable, is typically produced with low selectivity and follows the same trend as methane. Other work reported here indicated that methane selectivity increases with increasing temperature but is not excessively high at 230{degree}C. Consequently, the catalyst screening test should include an evaluation of the catalyst performance at 230{degree}C. During Run 67, the increase in temperature from 210{degree}C to 230{degree}C was initiated at 30 hours on-stream.

  7. A Cobalt-based Catalyst for CO2 Hydrogenation Under Ambient Conditions

    SciTech Connect (OSTI)

    Jeletic, Matthew S.; Mock, Michael T.; Appel, Aaron M.; Linehan, John C.

    2013-08-07

    Due to the continually rising levels of CO2 in the atmosphere, research into conversion of CO2 into fuels using carbon-neutral energy is currently an important topic in catalysis. Recent research on molecular catalysts has led to improved rates of CO2 conversion to formate, but unfortunately the resulting catalysts are based on precious metals such as iridium, ruthenium and rhodium and require high temperatures and high pressures for catalytic reactivity. Using established thermodynamic properties, a cobalt-based catalyst system has been designed for the catalytic production of formate from CO2 and H2, even at room temperature and one atmosphere of pressure. Using Co(dmpe)2H (dmpe is bis(dimethylphosphino)ethane) as a catalyst in tetrahydrofuran, room temperature turnover frequencies of 3,400 h-1 at 1 atm of 1:1 CO2:H2 and 74,000 h-1 at 20 atm were obtained. These results highlight the value of basic thermodynamic properties in the rational design of catalysts. This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

  8. Minimal Determinants for Binding Activated G alpha from the Structure of a G alpha i1-Peptide Dimer

    SciTech Connect (OSTI)

    Johnston,C.; Lobanova, E.; Shavkunov, A.; Low, J.; Ramer, J.; Blasesius, R.; Fredericks, Z.; willard, F.; Kuhlman, B.; et al.

    2006-01-01

    G-Proteins cycle between an inactive GDP-bound state and an active GTP-bound state, serving as molecular switches that coordinate cellular signaling. We recently used phage display to identify a series of peptides that bind G{alpha}subunits in a nucleotide-dependent manner [Johnston, C. A., Willard, F. S., Jezyk, M. R., Fredericks, Z., Bodor, E. T., Jones, M. B., Blaesius, R., Watts, V. J., Harden, T. K., Sondek, J., Ramer, J. K., and Siderovski, D. P. (2005) Structure 13, 1069-1080]. Here we describe the structural features and functions of KB-1753, a peptide that binds selectively to GDP{center_dot}AlF{sub 4{sup -}}- and GTP{gamma}S-bound states of G{alpha}{sup i} subunits. KB-1753 blocks interaction of G{alpha}{sub transducin} with its effector, cGMP phosphodiesterase, and inhibits transducin-mediated activation of cGMP degradation. Additionally, KB-1753 interferes with RGS protein binding and resultant GAP activity. A fluorescent KB-1753 variant was found to act as a sensor for activated G{alpha} in vitro. The crystal structure of KB-1753 bound to G{alpha}{sub i1}-GDP{center_dot}AlF{sub 4{sup -}} reveals binding to a conserved hydrophobic groove between switch II and 3 helices and, along with supporting biochemical data and previous structural analyses, supports the notion that this is the site of effector interactions for G{alpha}i subunits.

  9. Ligand Bridging-Angle-Driven Assembly of Molecular Architectures Based on Quadruply Bonded Mo-Mo Dimers

    SciTech Connect (OSTI)

    Li, Jian-Rong; Yakovenko, Andrey A; Lu, Weigang; Timmons, Daren J; Zhuang, Wenjuan; Yuan, Daqiang; Zhou, Hong-Cai

    2010-12-15

    A systematic exploration of the assembly of Mo?(O?C-)?-based metalorganic molecular architectures structurally controlled by the bridging angles of rigid organic linkers has been performed. Twelve bridging dicarboxylate ligands were designed to be of different sizes with bridging angles of 0, 60, 90, and 120 while incorporating a variety of nonbridging functional groups, and these ligands were used as linkers. These dicarboxylate linkers assemble with quadruply bonded MoMo clusters acting as nodes to give 13 molecular architectures, termed metalorganic polygons/polyhedra with metal cluster node arrangements of a linear shape, triangle, octahedron, and cuboctahedron/anti-cuboctahedron. The syntheses of these complexes have been optimized and their structures determined by single-crystal X-ray diffraction. The results have shown that the shape and size of the resulting molecular architecture can be controlled by tuning the bridging angle and size of the linker, respectively. Functionalization of the linker can adjust the solubility of the ensuing molecular assembly but has little or no effect on the geometry of the product. Preliminary gas adsorption, spectroscopic, and electrochemical properties of selected members were also studied. The present work is trying to enrich metal-containing supramolecular chemistry through the inclusion of well-characterized quadruply bonded MoMo units into the structures, which can widen the prospect of additional electronic functionality, thereby leading to novel properties.

  10. Actinide Corroles: Synthesis and Characterization of Thorium(IV) and Uranium(IV) bis(-chloride) Dimers

    SciTech Connect (OSTI)

    Ward, Ashleigh L.; Buckley, Heather L.; Gryko, Daniel T.; Lukens, Wayne W.; Arnold, John

    2013-12-01

    The first synthesis and structural characterization of actinide corroles is presented. Thorium(IV) and uranium(IV) macrocycles of Mes2(p-OMePh)corrole were synthesised and characterized by single-crystal X-ray diffraction, UV-Visible spectroscopy, variable-temperature 1H NMR, ESI mass spectrometry and cyclic voltammetry.

  11. Durable Catalysts for Fuel Cell Protection during Transient Conditions...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    1 - October 1, 2009 PDF icon atanasoskikickoff.pdf More Documents & Publications Catalysis Working Group Meeting: January 2015 Catalysis Working Group Meeting: June 2014 DOE's...

  12. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Filter Results Filter by Subject materials science (2) air conditioning (1) alloys (1) austenite (1) catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar ...

  13. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Filter Results Filter by Subject absorption spectroscopy (1) aging (1) air (1) anisotropy (1) armor (1) catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), ...

  14. CABS | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    Research Topics: catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), ... GC5 Non-equilibrium BRN Addressed CombustionTransportation Fuels Solar Energy Utilization

  15. Dr.James J.Spivey

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Books: cat Catalysis , volumes 12-21, published by the Royal Society of Chemistry (Cambridge, UK). nat Natural Gas Conversion VI, Studies in Surface Science and Catalysis , vol....

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    Office of Scientific and Technical Information (OSTI)

    ... Filter Results Filter by Subject materials science (23) catalysis (homogeneous), catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, ...

  17. Activity of N-coordinated multi-metal-atom active site structures for Pt-free oxygen reduction reaction catalysis: Role of *OH ligands

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Holby, Edward F.; Taylor, Christopher D.

    2015-03-19

    We report calculated oxygen reduction reaction energy pathways on multi-metal-atom structures that have previously been shown to be thermodynamically favorable. We predict that such sites have the ability to spontaneously cleave the O₂ bond and then will proceed to over-bind reaction intermediates. In particular, the *OH bound state has lower energy than the final 2 H₂O state at positive potentials. Contrary to traditional surface catalysts, this *OH binding does not poison the multi-metal-atom site but acts as a modifying ligand that will spontaneously form in aqueous environments leading to new active sites that have higher catalytic activities. These *OH boundmore »structures have the highest calculated activity to date.« less

  18. Activity of N-coordinated multi-metal-atom active site structures for Pt-free oxygen reduction reaction catalysis: Role of *OH ligands

    SciTech Connect (OSTI)

    Holby, Edward F.; Taylor, Christopher D.

    2015-03-19

    We report calculated oxygen reduction reaction energy pathways on multi-metal-atom structures that have previously been shown to be thermodynamically favorable. We predict that such sites have the ability to spontaneously cleave the O? bond and then will proceed to over-bind reaction intermediates. In particular, the *OH bound state has lower energy than the final 2 H?O state at positive potentials. Contrary to traditional surface catalysts, this *OH binding does not poison the multi-metal-atom site but acts as a modifying ligand that will spontaneously form in aqueous environments leading to new active sites that have higher catalytic activities. These *OH bound structures have the highest calculated activity to date.

  19. Probing the Mechanism of the Mycobacterium tuberculosis [beta]-Ketoacyl-Acyl Carrier Protein Synthase III mtFabH: Factors Influencing Catalysis and Substrate Specificity

    SciTech Connect (OSTI)

    Brown, Alistair K.; Sridharan, Sudharsan; Kremer, Laurent; Lindenberg, Sandra; Dover, Lynn G.; Sacchettini, James C.; Besra, Gurdyal S.

    2010-11-30

    Mycolic acids are the dominant feature of the Mycobacterium tuberculosis cell wall. These {alpha}-alkyl, {beta}-hydroxy fatty acids are formed by the condensation of two fatty acids, a long meromycolic acid and a shorter C{sub 24}-C{sub 26} fatty acid. The component fatty acids are produced via a combination of type I and II fatty acid synthases (FAS) with FAS-I products being elongated by FAS-II toward meromycolic acids. The {beta}-ketoacyl-acyl carrier protein (ACP) synthase III encoded by mtfabH (mtFabH) links FAS-I and FAS-II, catalyzing the condensation of FAS-I-derived acyl-CoAs with malonyl-acyl carrier protein (ACP). The acyl-CoA chain length specificity of mtFabH was assessed in vitro; the enzyme extended longer, physiologically relevant acyl-CoA primers when paired with AcpM, its natural partner, than with Escherichia coli ACP. The ability of the enzyme to use E. coli ACP suggests that a similar mode of binding is likely with both ACPs, yet it is clear that unique factors inherent to AcpM modulate the substrate specificity of mtFabH. Mutation of proposed key mtFabH residues was used to define their catalytic roles. Substitution of supposed acyl-CoA binding residues reduced transacylation, with double substitutions totally abrogating activity. Mutation of Arg{sup 46} revealed its more critical role in malonyl-AcpM decarboxylation than in the acyl-CoA binding role. Interestingly, this effect was suppressed intragenically by Arg{sup 161} {yields} Ala substitution. Our structural studies suggested that His{sup 258}, previously implicated in malonyl-ACP decarboxylation, also acts as an anchor point for a network of water molecules that we propose promotes deprotonation and transacylation of Cys{sup 122}.

  20. Synthesis and Exploratory Catalysis of 3d Metals: Group-Transfer Reactions, and the Activation and Functionalization of Small Molecules Including Greenhouse Gases

    SciTech Connect (OSTI)

    Mindiola, Daniel J.

    2014-05-07

    Our work over the past three years has resulted in the development of electron rich and low-coordinate vanadium fragments, molecular nitrides of vanadium and parent imide systems of titanium, and the synthesis of phosphorus containing molecules of the 3d transition metal series. Likewise, with financial support from BES Division in DOE (DE-FG02-07ER15893), we now completed the full characterization of the first single molecular magnet (SMM) of Fe(III). We demonstrated that this monomeric form of Fe(III) has an unusual slow relaxation of the magnetization under zero applied field. To make matters more interesting, this system also undergoes a rare example of an intermediate to high-spin transition (an S = 3/2 to S = 5/2 transition). In 2010 we reported the synthesis of the first neutral and low-coordinate vanadium complexes having the terminal nitride functionality. We have now completed a full study to understand formation of the nitride ligand from the metastable azide precursor, and have also explored the reactivity of the nitride ligand in the context of incomplete and complete N-atom transfer. During the 2010-2013 period we also discovered a facile approach to assemble low-coordinate and low-valent vanadium(II) complexes and exploit their multielectron chemistry ranging from 1-3 electrons. Consequently, we can now access 3d ligand frameworks such as cyclo-P3 (and its corresponding radical anion), nitride radical anions and cations, low-coordinate vanadium oxo’s, and the first example of a vanadium thionitrosyl complex. A cis-divacant iron(IV) imido having some ligand centered radical has been also discovered, and we are in the process of elucidating its electronic structure (in particular the sign of zero field splitting and the origin of its magnitude), bonding and reactivity. We have also revisited some paramagnetic and classic metallocene compounds with S >1/2 ground states in order to understand their reactivity patterns and electronic structure. Lastly, we are completing the synthesis and characterization of a titanium nitride anion and formation of the first example of boryl and aluminyl imido titanium complexes.

  1. Combined UHV/high-pressure catalysis setup for depth-resolved near-surface spectroscopic characterization and catalytic testing of model catalysts

    SciTech Connect (OSTI)

    Mayr, Lukas; Kltzer, Bernhard; Penner, Simon; Rameshan, Raffael; Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin ; Rameshan, Christoph; Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9/BC/01, 1060 Vienna

    2014-05-15

    An ultra-high vacuum (UHV) setup for real and inverse model catalyst preparation, depth-resolved near-surface spectroscopic characterization, and quantification of catalytic activity and selectivity under technologically relevant conditions is described. Due to the all-quartz reactor attached directly to the UHV-chamber, transfer of the catalyst for in situ testing without intermediate contact to the ambient is possible. The design of the UHV-compatible re-circulating batch reactor setup allows the study of reaction kinetics under close to technically relevant catalytic conditions up to 1273 K without contact to metallic surfaces except those of the catalyst itself. With the attached differentially pumped exchangeable evaporators and the quartz-microbalance thickness monitoring equipment, a reproducible, versatile, and standardised sample preparation is possible. For three-dimensional near-surface sample characterization, the system is equipped with a hemispherical analyser for X-ray photoelectron spectroscopy (XPS), electron-beam or X-ray-excited Auger-electron spectroscopy, and low-energy ion scattering measurements. Due the dedicated geometry of the X-ray gun (54.7, magic angle) and the rotatable sample holder, depth analysis by angle-resolved XPS measurements can be performed. Thus, by the combination of characterisation methods with different information depths, a detailed three-dimensional picture of the electronic and geometric structure of the model catalyst can be obtained. To demonstrate the capability of the described system, comparative results for depth-resolved sample characterization and catalytic testing in methanol steam reforming on PdGa and PdZn near-surface intermetallic phases are shown.

  2. Catalysis for Mixed Alcohol Synthesis from Biomass Derived Syngas: Cooperative Research and Development Final Report, CRADA Number CRD-08-292

    SciTech Connect (OSTI)

    Hensley, J.

    2013-04-01

    The Dow Chemical Company (Dow) developed and tested catalysts for production of mixed alcohols from synthesis gas (syngas), under research and development (R&D) projects that were discontinued a number of years ago. Dow possesses detailed laboratory notebooks, catalyst samples, and technical expertise related to this past work. The National Renewable Energy Laboratory (NREL) is conducting R&D in support of the United States Department of Energy (DOE) to develop methods for economically producing ethanol from gasified biomass. NREL is currently conducting biomass gasification research at an existing 1/2 ton/day thermochemical test platform. Both Dow and NREL believe that the ability to economically produce ethanol from biomass-derived syngas can be enhanced through collaborative testing, refinement, and development of Dow's mixed-alcohol catalysts at NREL's and/or Dow's bench- and pilot-scale facilities. Dow and NREL further agree that collaboration on improvements in catalysts as well as gasifier operating conditions (e.g., time, temperature, upstream gas treatment) will be necessary to achieve technical and economic goals for production of ethanol and other alcohols.

  3. Retrofit Program of a Euro 1 andn EUro 2 Urban Bus Fleet in La Rochelle: Status after One Year Experience

    Broader source: Energy.gov [DOE]

    2004 Diesel Engine Emissions Reduction (DEER) Conference Presentation: Rhodia Electronics and Catalysis

  4. A full dimensional investigation of infrared spectroscopy of the RbCs dimer using the multi-configuration time-dependent Hartree method

    SciTech Connect (OSTI)

    Wang, Huihui; Yang, Yonggang Xiao, Liantuan; Jia, Suotang

    2013-12-28

    The geometry and infrared absorption spectrum of (RbCs){sub 2} have been studied by full dimensional quantum dynamics simulations. For this purpose, the potential energy and dipole moment surfaces are generated by means of a cluster expansion with all two and three mode correlations, and fitted to analytical expressions with negligible deviations. Accordingly, the ground state (RbCs){sub 2} has a diamond geometry with D{sub 2h} symmetry. The infrared spectrum with frequencies up to 120 cm{sup −1}, exhibits rich details of the fundamentals, overtones, and combination bands; the highest fundamental frequency of (RbCs){sub 2} is only 40.26 cm{sup −1}. The present study unravels important details of the interactions between the widely investigated ultracold RbCs molecules.

  5. Solid flexible electrochemical supercapacitor using Tobacco mosaic virus

    Office of Scientific and Technical Information (OSTI)

    nanostructures and ALD ruthenium oxide (Journal Article) | SciTech Connect Solid flexible electrochemical supercapacitor using Tobacco mosaic virus nanostructures and ALD ruthenium oxide Citation Details In-Document Search Title: Solid flexible electrochemical supercapacitor using Tobacco mosaic virus nanostructures and ALD ruthenium oxide Authors: Gnerlich, Markus ; Pomerantseva, Ekaterina ; Gregorczyk, Keith ; Ketchum, D ; Rubloff, Gary W ; Ghodssi, Reza Publication Date: 2013-10-24 OSTI

  6. Nitric acid recovery from waste solutions

    DOE Patents [OSTI]

    Wilson, A. S.

    1959-04-14

    The recovery of nitric acid from aqueous nitrate solutions containing fission products as impurities is described. It is desirable to subject such solutions to concentration by evaporation since nitric acid is regenerated thereby. A difficulty, however, is that the highly radioactive fission product ruthenium is volatilized together with the nitric acid. It has been found that by adding nitrous acid, ruthenium volatilization is suppressed and reduced to a negligible degree so that the distillate obtained is practically free of ruthenium.

  7. Improving the efficiency of water splitting in dye-sensitized...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    bound to the water oxidation catalyst, a colloidal iridium oxide particle, and is coadsorbed onto a porous titanium dioxide electrode with a Ruthenium polypyridyl sensitizer. ...

  8. Correlation between microstructure and thermionic electron emission...

    Office of Scientific and Technical Information (OSTI)

    were evaluated with scanning electron microscopy, x-ray diffraction, and energy ... OSMIUM; RUTHENIUM; SCANNING ELECTRON MICROSCOPY; THIN FILMS; X-RAY DIFFRACTION; X-RAY ...

  9. Isotope Permeability Through Materials S. A. Steward

    Office of Scientific and Technical Information (OSTI)

    ... abilities for any of the following pure metals: antimony, arsenic, bismuth, boron, chromium, indium, iridium, manganese, osmium, rhenium, rhodium, ruthenium, tin, and thallium. ...

  10. Solid flexible electrochemical supercapacitor using Tobacco mosaic...

    Office of Scientific and Technical Information (OSTI)

    mosaic virus nanostructures and ALD ruthenium oxide Citation Details In-Document Search Title: Solid flexible electrochemical supercapacitor using Tobacco mosaic virus ...

  11. Crystal structure of 3,4-dihydroxy-2-butanone 4-phosphate synthase of riboflavin biosynthesis

    SciTech Connect (OSTI)

    Liao, D.-I.; Calabrese, J.C.; Wawrzak, Z.; Viitanen, P.V.; Jordan, D.B.

    2010-03-05

    3,4-Dihydroxy-2-butanone-4-phosphate synthase catalyzes a commitment step in the biosynthesis of riboflavin. On the enzyme, ribulose 5-phosphate is converted to 3,4-dihydroxy-2-butanone 4-phosphate and formate in steps involving enolization, ketonization, dehydration, skeleton rearrangement, and formate elimination. The enzyme is absent in humans and an attractive target for the discovery of antimicrobials for pathogens incapable of acquiring sufficient riboflavin from their hosts. The homodimer of 23 kDa subunits requires Mg{sup 2+} for activity. The first three-dimensional structure of the enzyme was determined at 1.4 {angstrom} resolution using the multiwavelength anomalous diffraction (MAD) method on Escherichia coli protein crystals containing gold. The protein consists of an {alpha} + {beta} fold having a complex linkage of {beta} strands. Intersubunit contacts are mediated by numerous hydrophobic interactions and three hydrogen bond networks. A proposed active site was identified on the basis of amino acid residues that are conserved among the enzyme from 19 species. There are two well-separated active sites per dimer, each of which comprise residues from both subunits. In addition to three arginines and two threonines, which may be used for recognizing the phosphate group of the substrate, the active site consists of three glutamates, two aspartates, two histidines, and a cysteine which may provide the means for general acid and base catalysis and for coordinating the Mg{sup 2+} cofactor within the active site.

  12. Structure of the JmjC domain-containing protein NO66 complexed with ribosomal protein Rpl8

    SciTech Connect (OSTI)

    Wang, Chengliang; Zhang, Qiongdi; Hang, Tianrong; Tao, Yue; Ma, Xukai; Wu, Minhao; Zhang, Xuan Zang, Jianye

    2015-08-28

    The structure of the complex of NO66 and Rpl8 was solved in the native state and NO66 recognizes the consensus motif NHXH . Tetramerization is required for efficient substrate binding and catalysis by NO66. The JmjC domain-containing proteins belong to a large family of oxygenases possessing distinct substrate specificities which are involved in the regulation of different biological processes, such as gene transcription, RNA processing and translation. Nucleolar protein 66 (NO66) is a JmjC domain-containing protein which has been reported to be a histone demethylase and a ribosome protein 8 (Rpl8) hydroxylase. The present biochemical study confirmed the hydroxylase activity of NO66 and showed that oligomerization is required for NO66 to efficiently catalyze the hydroxylation of Rpl8. The structures of NO66{sup 176–C} complexed with Rpl8{sup 204–224} in a tetrameric form and of the mutant protein M2 in a dimeric form were solved. Based on the results of structural and biochemical analyses, the consensus sequence motif NHXH recognized by NO66 was confirmed. Several potential substrates of NO66 were found by a BLAST search according to the consensus sequence motif. When binding to substrate, the relative positions of each subunit in the NO66 tetramer shift. Oligomerization may facilitate the motion of each subunit in the NO66 tetramer and affect the catalytic activity.

  13. [Transition metal mediated transformations of small molecules

    SciTech Connect (OSTI)

    Sen, A.

    1992-01-01

    Work on organotransition metal chemistry, homogeneous and heterogeneous catalysis is summarized. Several cationic palladium(II) complexes with bulky phosphine or pyridine ligands were discovered that are highly selective catalysts for linear dimerization of vinyl monomers and linear polymerization of p-divinylbenzene, the reactions proceeding through a carbocationic mechanism. Our studies were continued on alternating olefin-carbon monoxide copolymers. The copolymerization reaction and reactivity of copolymers were examined. New catalytic systems for alternating copolymerization of [alpha]-olefins with CO were discovered. In the case of styrene derivatives, tactic copolymers were obtained. Poly(ethylenepyrrolediyl) derivatives were synthesized from alternating ethylene-carbon monoxide copolymer and become electronic conductors when doped with iodine. A catalytic system for direct synthesis of polyureas and polyoxamides from and diamines was also discovered. Pt metal catalyzed the oxidation of ethers, esters, and amines to carboxylic acids and the oxidation of olefins to 1,2-diols. Anaerobic and aerobic decomposition of molybdenum(VI)-oxoalkyl compounds were studied for heterogeneous oxidation of alkanes and olefins on Mo(VI)-oxide surfaces. Synthesis of polymer-trapped metal, metal oxide, and metal sulfide nanoclusters (size <1--10 nm) was studied.

  14. [Transition metal mediated transformations of small molecules]. Progress report

    SciTech Connect (OSTI)

    Sen, A.

    1992-10-01

    Work on organotransition metal chemistry, homogeneous and heterogeneous catalysis is summarized. Several cationic palladium(II) complexes with bulky phosphine or pyridine ligands were discovered that are highly selective catalysts for linear dimerization of vinyl monomers and linear polymerization of p-divinylbenzene, the reactions proceeding through a carbocationic mechanism. Our studies were continued on alternating olefin-carbon monoxide copolymers. The copolymerization reaction and reactivity of copolymers were examined. New catalytic systems for alternating copolymerization of {alpha}-olefins with CO were discovered. In the case of styrene derivatives, tactic copolymers were obtained. Poly(ethylenepyrrolediyl) derivatives were synthesized from alternating ethylene-carbon monoxide copolymer and become electronic conductors when doped with iodine. A catalytic system for direct synthesis of polyureas and polyoxamides from and diamines was also discovered. Pt metal catalyzed the oxidation of ethers, esters, and amines to carboxylic acids and the oxidation of olefins to 1,2-diols. Anaerobic and aerobic decomposition of molybdenum(VI)-oxoalkyl compounds were studied for heterogeneous oxidation of alkanes and olefins on Mo(VI)-oxide surfaces. Synthesis of polymer-trapped metal, metal oxide, and metal sulfide nanoclusters (size <1--10 nm) was studied.

  15. Lean-NOx Catalyst Development for Diesel Engine Applications | Department

    Broader source: Energy.gov (indexed) [DOE]

    of Energy 2 DEER Conference Presentation: Caterpillar Inc. PDF icon 2002_deer_park.pdf More Documents & Publications Lean NOx Catalysis Research and Development Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control

  16. Heavy-Duty NOx Emissions Control: Reformer-Assisted vs. Plasma...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    NOx Emissions Control: Reformer-Assisted vs. Plasma-Facilitated Lean NOx Catalysis Heavy-Duty NOx Emissions Control: Reformer-Assisted vs. Plasma-Facilitated Lean NOx Catalysis ...

  17. Towards graphyne molecular electronics (Journal Article) | SciTech...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: catalysis (heterogeneous), solar (photovoltaic), energy storage (including batteries and capacitors), hydrogen and...

  18. Beamline 9.3.2

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    2 Print Chemical and Materials Scientific disciplines: Surfaces, interfaces, catalysis, environmental science, material science, electrochemistry Endstations: Ambient pressure...

  19. A Light-Stimulated Molecular Switch Driven by Radical-Radical...

    Office of Scientific and Technical Information (OSTI)

    United States Language: English Subject: catalysis (homogeneous), solar (photovoltaic), bio-inspired, charge transport, mesostructured materials, materials and chemistry...

  20. High-pressure phases of a hydrogen-rich compound: Tetramethylgermane...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and...

  1. Constraint on the potassium content for the superconductivity...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and...

  2. Vibrational and structural properties of tetramethyltin under...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and...

  3. Formation of Nanofoam carbon and re-emergence of Superconductivity...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and...

  4. First-principles investigations on the magnetic property in tripotassi...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and...

  5. Pressure induced superconductivity in CaC2 (Journal Article)...

    Office of Scientific and Technical Information (OSTI)

    of Publication: United States Language: English Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and...

  6. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, charge ...

  7. The Challenges for PEMFC Catalysts in Automotive Applications

    Broader source: Energy.gov [DOE]

    Presentation by Stephen Campbell for the 2013 DOE Catalysis Working Group Meeting on PEMFC catalysts in automotive applications.

  8. Pressure-Driven Quantum Criticality in An Iron-Selenide Superconductor...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, ...

  9. Structural properties of BaFe1.8Ni0.2As2 under pressure (Journal...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, ...

  10. Pressure-induced phase coexistence in BaFe1.8Co0.2As2 (Journal...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, ...

  11. Structural feature controlling superconductivity in compressed...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel cells, superconductivity, ...

  12. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Filter Results Filter by Subject catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel ...

  13. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    (1) barium compounds (1) binding energy (1) catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), ...

  14. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    physics (1) atomic models (1) bond angle (1) catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), ...

  15. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    phase transformations (4) raman spectroscopy (4) catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), ...

  16. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    (2) catalysis (homogeneous), solar (photovoltaic), bio-inspired, charge transport, ... improve both the photovoltaic and mechanical properties of polymeric materials. ...

  17. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Filter Results Filter by Subject catalysis (heterogeneous), solar (photovoltaic), phonons, ... (3) raman spectroscopy (3) solar (photovoltaic) (3) superconductivity (3) synthesis ...

  18. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    (4) raman spectroscopy (4) synthesis (4) catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), ...

  19. Center for Molecular Electrocatalysis (CME) | U.S. DOE Office...

    Office of Science (SC) Website

    To understand and design molecular electrocatalysts for conversions between electrical energy and chemical energy. Research Topics catalysis (homogeneous), solar (fuels), ...

  20. NREL: Awards and Honors - Electroexploded Metal Nanopowders

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Metal Nanopowders include catalysis, batteries, microelectronic contacts, lubrication, sinteringwelding, coating substrates for wear or corrosion resistance, and more...

  1. Lignin Utilization Presentation for BETO 2015 Project Peer Review

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ... * Combined metabolic engineering, fermentation, separations, and catalysis * ... Key Stakeholders and Impacts: - Industrial and academic research focused on ...

  2. Thermal equation of state and spin transition of magnesiosiderite...

    Office of Scientific and Technical Information (OSTI)

    Citation Details In-Document Search Title: Thermal equation of ... Subject: catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including ...

  3. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... catalysis (heterogeneous), solar (photovoltaic), solar (fuels), photosynthesis (natural and artificial), hydrogen and fuel cells, electrodes - solar, charge transport, ...

  4. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... (2) calcium carbonate (1) catalysis (heterogeneous), solar (fuels), photosynthesis (natural and artificial), bio-inspired, electrodes - solar, defects, charge transport, ...

  5. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Filter Results Filter by Subject catalysis (heterogeneous), solar (photovoltaic), phonons, thermoelectric, energy storage (including batteries and capacitors), hydrogen and fuel ...

  6. HeteroFoaM | U.S. DOE Office of Science (SC)

    Office of Science (SC) Website

    as fuel cells, batteries, supercapacitors, electrolyzers, and solid membranes. Research Topics: catalysis (heterogeneous), energy storage (including batteries and capacitors), ...

  7. Fluid Interface Reactions, Structures and Transport Center (FIRST...

    Office of Science (SC) Website

    Research Topics catalysis (heterogeneous), energy storage (including batteries and capacitors), charge transport, mesostructured materials, materials and chemistry by design, ...

  8. Thomas Jaramillo - JCAP

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    thomas jaramillo Principal Investigator and Research Thrust Coordinator Email: jaramillo@stanford.edu Dr. Jaramillo's research interests center around: energy and catalysis, engineering surface and bulk materials chemistry in relation to energy conversion reactions-production, utilization, and storage. General themes include nano-scale effects in heterogeneous catalysis and electro-catalysis. Topics include water electrolysis, fuel cell electrocatalysis (oxygen reduction, fuel oxidation,

  9. Pt3Ru6 Clusters Supported on gamma-Al2O3: Synthesis from Pt3Ru6(Cu)21(u3-H)(u-H)3, Structural Characterization, and Catalysis of Ethylene Hydrogenation and n-Butane Hydrogenolysis

    SciTech Connect (OSTI)

    Chotisuwan,S.; Wittayakun, J.; Gates, B.

    2006-01-01

    The supported clusters Pt-Ru/{gamma}-Al{sub 2}O{sub 3} were prepared by adsorption of the bimetallic precursor Pt{sub 3}Ru{sub 6}(Cu){sub 21}({mu}{sub 3}-H)({mu}-H){sub 3} from CH{sub 2}Cl{sub 2} solution onto {gamma}-Al{sub 2}O{sub 3} followed by decarbonylation in He at 300 C. The resultant supported clusters were characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies and as catalysts for ethylene hydrogenation and n-butane hydrogenolysis. After adsorption, the {nu}{sub CO} peaks characterizing the precursor shifted to lower wavenumbers, and some of the hydroxyl bands of the support disappeared or changed, indicating that the CO ligands of the precursor interacted with support hydroxyl groups. The EXAFS results show that the metal core of the precursor remained essentially unchanged upon adsorption, but there were distortions of the metal core indicated by changes in the metal-metal distances. After decarbonylation of the supported clusters, the EXAFS data indicated that Pt and Ru atoms interacted with support oxygen atoms and that about half of the Pt-Ru bonds were maintained, with the composition of the metal frame remaining almost unchanged. The decarbonylated supported bimetallic clusters reported here are the first having essentially the same metal core composition as that of a precursor metal carbonyl, and they appear to be the best-defined supported bimetallic clusters. The material was found to be an active catalyst for ethylene hydrogenation and n-butane hydrogenolysis under conditions mild enough to prevent substantial cluster disruption.

  10. Atomic force microscopy and x-ray photoelectron spectroscopy investigations of the morphology and chemistry of a PdCl{sub 2}/SnCl{sub 2} electroless plating catalysis system adsorbed onto shape memory alloy particles

    SciTech Connect (OSTI)

    Silvain, J.F.; Fouassier, O.; Lescaux, S.

    2004-11-01

    A study of the different stages of the electroless deposition of copper on micronic NiTi shape memory alloy particles activated by one-step and two-step methods has been conducted from both a chemical and a morphological point of view. The combination of x-ray photoelectron spectroscopy (XPS) measurements and atomic force microscopy (AFM) imaging has allowed detection of the distribution of the formed compounds and depth quantification and estimation of the surface topographic parameters. For the two-step method, at the sensitization of the early stages, it is observed by AFM that Sn is absorbed in form of clusters that tend to completely cover the surface and form a continuous film. XPS analysis have shown that Sn and Pd are first absorbed in form of oxide (SnO{sub 2} and PdO) and hydroxide [Sn(OH){sub 4}]. After the entire sensitization step, the NiTi substrate is covered with Sn-based compounds. After the sensitization and the activation steps the powder roughness increases. Behavior of the Sn and Pd growth for the one-step method does not follow the behavior found for the two-step method. Indeed, XPS analysis shows a three-dimensional (3D) growth of Pd clusters on top of a mixture of metallic tin, oxide (SnO) and hydroxide [Sn(OH){sub 2}]. These Pd clusters are covered with a thin layer of Pd-oxide contamination induced by the electroless process. The mean roughness for the one-step and two-step processes are equivalent. After copper deposition, the decrease of mean roughness is attributed to a filling of surface valleys, observed after the Sn-Pd coating step.

  11. A Hydrogen-Evolving Ni(P2N2)2 Electrocatalyst Covalently Attached to a Glassy Carbon Electrode: Preparation, Characterization, and Catalysis. Comparisons With the Homogeneous Analog

    SciTech Connect (OSTI)

    Das, Atanu K.; Engelhard, Mark H.; Bullock, R. Morris; Roberts, John A.

    2014-07-07

    A hydrogen-evolving homogeneous Ni(P2N2)2 electrocatalyst with peripheral ester groups has been covalently attached to a 1,2,3-triazolyllithium-terminated glassy carbon electrode. The surface-confined complex is an electroctalyst for hydrogen evolution, showing onset of catalytic current at the same potential as the soluble parent complex. X-ray photoemission spectra show excellent agreement between the coupled and homogeneous species. Coverage approaches a dense monolayer. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. The XPS measurements were performed at EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  12. Task 4.9 -- Value-added products from syngas

    SciTech Connect (OSTI)

    Olson, E.S.; Sharma, R.K.

    1997-02-01

    The work on advanced fuel forms in 1996 focused on the synthesis of higher alcohols from mixtures of hydrogen and carbon dioxide (syngas) from coal gasification. The conversion of coal gasification products to commercially valuable alcohols will provide an important new market for current and future gasification plants. Initial work in this project utilized a novel molybdenum sulfide catalyst previously shown to be active for hydrodesulfurization reactions of coal liquids. The support for the active metal sulfide is a layered mixed oxide (hydrotalcite) capable of interaction with the metal sites for catalysis of carbon monoxide reductions. These catalysts have a high surface area, are highly porous, and have basic and acidic functionality. A pressurized fixed-bed flow-through reactor was constructed, and the MoS{sub 2} catalysts were tested with syngas under a variety of conditions. Unfortunately, the catalysts, even with higher molybdenum loading and addition of promoters, failed to give alcohol products. A batch reactor test of the catalyst was also conducted, but did not produce alcohol products. Group 8 metals have been used previously in catalysts for syngas reactions. Ruthenium and rhodium catalysts were prepared by impregnation of a hydrotalcite support. Tests with these catalysts in flow-through reactors also did not produce the desired alcohol products. The formation of higher alcohols from smaller ones, such as methanol and ethanol, could be commercially important if high selectivity could be achieved. The methanol and ethanol would be derived from syngas and fermentation, respectively. Based on previous work in other laboratories, it was hypothesized that the hydrotalcite supported MoS{sub 2} or Ru or Rh catalysts could catalyze the formation of butyl alcohols. Although the desired 1-butanol was obtained in batch reactions with the promoted Ru catalyst, the reaction was not as selective as desired. Product suitable for a lower-vapor-pressure gasoline oxygenate additive was obtained, but it may not be economical to market such products in competition with methyl tertiary-butyl-ether. Flow-through catalytic bed reactions were not successful.

  13. Rate enhancement for catalytic upgrading coal naphthas. Final of final technical progress report, July 1991--September 1994

    SciTech Connect (OSTI)

    Davis, B.H.

    1995-08-01

    The objective of this project is to remove sulfur, nitrogen, and oxygen from naphtha derived from coal liquefaction. The project is concerned with the development of hydrotreating catalysts. This period, a ruthenium sulfide catalyst has been studied.

  14. Alcohol homologation

    DOE Patents [OSTI]

    Wegman, R.W.; Moloy, K.G.

    1988-02-23

    A process is described for the homologation of an alkanol by reaction with synthesis gas in contact with a system containing rhodium atom, ruthenium atom, iodine atom and a bis(diorganophosphino) alkane to selectivity produce the next higher homologue.

  15. Alcohol homologation

    DOE Patents [OSTI]

    Wegman, Richard W.; Moloy, Kenneth G.

    1988-01-01

    A process for the homologation of an alkanol by reaction with synthesis gas in contact with a system containing rhodium atom, ruthenium atom, iodine atom and a bis(diorganophosphino) alkane to selectivity produce the next higher homologue.

  16. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... The metal sorbents can be used as pure metals (or combinations of metals) or dispersed on an inert support to increase surface area per gram of metal sorbent. Iridium and ruthenium ...

  17. NITRIC ACID RECPVERY FROM WASTE COLUTIONS

    DOE Patents [OSTI]

    Wilson, A.S.

    1959-04-14

    The recovery of nitric acid from aqueous nitrate solutions containing fission products as impurities is described. It is desirable to subject such solutions to concentration by evaporation since nitric acid is regenerated thereby. A difficulty, however, is that the highly radioactive fission product ruthenium is volatilized together with the nitric acid. It has been found that by adding nitrous acids ruthenium volatilization is suppressed and reduced to a negligible degree so that the distillate obtained is practically free of rutheniuim.

  18. SSRL HEADLINES February 2012

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Increasing Catalysis Capabilities at SSRL Chi-Chang Kao With each passing week, SSRL's five-to-ten year strategic goals are becoming increasingly well defined. Previous columns have presented our plans for Materials Science and Outreach and Support Efforts; in this column, we cover our goals for catalysis research at the light source. Catalysis is the essential mechanism for directing and accelerating chemical reactions. The development of efficient and selective catalysts is key to enabling use

  19. Now on display: a gallery of group II intron structures at different stages

    Office of Scientific and Technical Information (OSTI)

    of catalysis (Journal Article) | SciTech Connect SciTech Connect Search Results Journal Article: Now on display: a gallery of group II intron structures at different stages of catalysis Citation Details In-Document Search Title: Now on display: a gallery of group II intron structures at different stages of catalysis Authors: Marcia, Marco ; Somarowthu, Srinivas ; Pyle, Anna M. [1] ; HHMI) [2] + Show Author Affiliations (Yale) ( Publication Date: 2013-09-25 OSTI Identifier: 1086313 Resource

  20. Heavy-Duty NOx Emissions Control: Reformer-Assisted vs. Plasma-Facilitated

    Broader source: Energy.gov (indexed) [DOE]

    Lean NOx Catalysis | Department of Energy 03 DEER Conference Presentation: Pacific Northwest National Laboratory PDF icon 2003_deer_aardahl.pdf More Documents & Publications Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control Selective reduction of NOx in oxygen rich environments with plasma-assisted catalysis: Catalyst development and mechanistic studies Lean-NOx Catalyst Development for Diesel Engine Applications