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Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
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We encourage you to perform a real-time search of NLEBeta
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1

Blue Ruthenium Dimer Catalysis for Hydrogen Generation | Advanced Photon  

NLE Websites -- All DOE Office Websites (Extended Search)

A High-Pressure Nano-imaging Breakthrough A High-Pressure Nano-imaging Breakthrough Protein Structure Could Lead to Better Treatments for HIV, Early Aging The Superpower behind Iron Oxyfluoride Battery Electrodes Watching a Protein as it Functions Shedding Light on Chemistry with a Biological Twist Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed Blue Ruthenium Dimer Catalysis for Hydrogen Generation APRIL 15, 2013 Bookmark and Share Key intermediates in the water oxidation catalytic cycle of the blue dimer characterized by x-ray spectroscopy. Optimization of the reactivity toward water (purple arrow) and oxidation of the resulting peroxo-intermediate (blue arrow) are needed for improved catalytic activity.

2

Catalysis  

Science Conference Proceedings (OSTI)

Catalysis presents the physicist with an excellent opportunity to contribute to the technology of energy supply by doing basic research. Recent developments in the experimental techniques for the preparation and investigation of solid surfaces and adsorbates and in the electronic theory of surfaces and of chemisorption quite naturally will provide insights into the fundamental processes of catalysis that were not accessible before and hold the promise of making catalysis an exact science in the foreseeable future. Such knowledge can be expected to promote in a significant way the discovery of new catalysts that will be necessary in the technology of energy production. An analysis of our natural resources reveals that for the next 50 years the major part of our energy supply will have to be provided by fossil fuels. The depletion of oil reserves makes it necessary to transform coal

T. E. Fischer

1974-01-01T23:59:59.000Z

3

Catalysis Workshop  

NLE Websites -- All DOE Office Websites (Extended Search)

Opportunities in Catalysis Research Using Synchrotron Radiation 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 metals, etc. The fundamental understanding of many catalytic processes is still emerging and there seems to be a new opportunity with the recent development in experimental and theoretical methods. The intention of workshop was to bring researchers from many different disciplines together to discuss how synchrotron radiation can be applied to address some fundamental questions in catalysis.

4

Catalysis and Biocatalysis Technologies  

Science Conference Proceedings (OSTI)

ATP FOCUSED PROGRAM: Catalysis and Biocatalysis Technologies NOTE ... pharmaceuticals. And that only hints at the roles catalysis plays. ...

2011-10-19T23:59:59.000Z

5

It's Elemental - The Element Ruthenium  

NLE Websites -- All DOE Office Websites (Extended Search)

Technetium Previous Element (Technetium) The Periodic Table of Elements Next Element (Rhodium) Rhodium The Element Ruthenium Click for Isotope Data 44 Ru Ruthenium 101.07 Atomic...

6

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis & Energy Conversion * Heterogeneous Catalysis * Homogeneous Catalysis * Fuel Cell Engineering * Hydrogen & Fuel Cell Materials * Ceramic Electrochemistry Catalysis &...

7

2012 Catalysis Lectures  

NLE Websites -- All DOE Office Websites (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...

8

Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis  

SciTech Connect

Mechanistic Studies at the Interface Between Organometallic Chemistry and Homogeneous Catalysis Charles P. Casey, Principal Investigator Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706 Phone 608-262-0584 FAX: 608-262-7144 Email: casey@chem.wisc.edu http://www.chem.wisc.edu/main/people/faculty/casey.html Executive Summary. Our goal was to learn the intimate mechanistic details of reactions involved in homogeneous catalysis and to use the insight we gain to develop new and improved catalysts. Our work centered on the hydrogenation of polar functional groups such as aldehydes and ketones and on hydroformylation. Specifically, we concentrated on catalysts capable of simultaneously transferring hydride from a metal center and a proton from an acidic oxygen or nitrogen center to an aldehyde or ketone. An economical iron based catalyst was developed and patented. Better understanding of fundamental organometallic reactions and catalytic processes enabled design of energy and material efficient chemical processes. Our work contributed to the development of catalysts for the selective and mild hydrogenation of ketones and aldehydes; this will provide a modern green alternative to reductions by LiAlH4 and NaBH4, which require extensive work-up procedures and produce waste streams. (C5R4OH)Ru(CO)2H Hydrogenation Catalysts. Youval Shvo described a remarkable catalytic system in which the key intermediate (C5R4OH)Ru(CO)2H (1) has an electronically coupled acidic OH unit and a hydridic RuH unit. Our efforts centered on understanding and improving upon this important catalyst for reduction of aldehydes and ketones. Our mechanistic studies established that the reduction of aldehydes by 1 to produce alcohols and a diruthenium bridging hydride species occurs much more rapidly than regeneration of the ruthenium hydride from the diruthenium bridging hydride species. Our mechanistic studies require simultaneous transfer of hydride from ruthenium to the aldehyde carbon and of a proton from the CpOH unit to the aldehyde oxygen and support reduction of the aldehyde without its prior coordination to ruthenium. Another important step in the catalysis is the regeneration of 1 from reaction of H2 with the stable diruthenium bridging hydride complex 2. Studies of the microscopic reverse of this process (hydrogen evolution from 1 which occurs at 80 �������°C) in the presence of alcohol (the product of aldehyde hydrogenation) have shown that a dihydrogen complex is formed reversibly at a rate much faster than hydrogen evolution. Kinetic and theoretical studies in collaboration with Professor Qiang Cui of Wisconsin indicated an important role for alcohol in mediating transfer of hydrogen to ruthenium. One key to developing more active catalysts was to destabilize the bridging hydride intermediate 2 to prevent its formation or to speed its conversion to a reactive monohydride 1 by reaction with H2. We found several successful ways to destabilize the bridging hydride and to obtain more active catalysts. Most recently, we discovered related iron catalysts for hydrogenation that do not form dimers; the cost advantage of iron catalysts is spectacular. Iron Catalysts. In an exciting development, we found that a related iron complex is also a very active ketone hydrogenation catalyst. This hydrogenation catalyst shows high chemoselectivity for aldehydes, ketones, and imines and isolated C=C, C���¯�������ºC, C-X, -NO2, epoxides, and ester functions are unaffected by the hydrogenation conditions. Mechanistic studies have established a reversible hydrogen transfer step followed by rapid dihydrogen activation. The same iron complex also catalyzes transfer hydrogenation of ketones.

Charles P. Casey

2012-11-14T23:59:59.000Z

9

A Further Understanding of Superconductivity | Advanced Photon...  

NLE Websites -- All DOE Office Websites (Extended Search)

Evolution Could Guide HIV Vaccine Development Blue Ruthenium Dimer Catalysis for Hydrogen Generation Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 |...

10

RUTHENIUM DECONTAMINATION METHOD  

DOE Patents (OSTI)

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.

Gresky, A.T.

1960-07-19T23:59:59.000Z

11

Catalysis Science at Brookhaven  

NLE Websites -- All DOE Office Websites (Extended Search)

and energy conversion. Reactivity-structure correlations explored and unraveled by utilization of synchrotron radiation are a key aspect of these studies. Catalysis on the...

12

Moderated ruthenium fischer-tropsch synthesis catalyst  

DOE Patents (OSTI)

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.

Abrevaya, Hayim (Wilmette, IL)

1991-01-01T23:59:59.000Z

13

SEPARATION OF RUTHENIUM FROM AQUEOUS SOLUTIONS  

DOE Patents (OSTI)

>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.

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

1959-09-01T23:59:59.000Z

14

Energy Programs | Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Catalysis Driving Toward Alternative Fuels Page 1 of 2 About 85 percent of the nation's energy needs are met by the combustion of fossil fuels such as oil, natural gas, and coal - finite resources that make the United States dependent upon other countries while polluting the environment through carbon emissions. In order to achieve energy security in an environmentally friendly manner, the nation's energy strategy must include alternative technologies based on renewable sources such as biofuels, solar, wind, and nuclear power. A central challenge, however, is the development of new processes and materials capable of tapping these sources and feeding the country's vast energy needs. A key part of the solution involves catalysis, the process of speeding up and

15

It's Elemental - Isotopes of the Element Ruthenium  

NLE Websites -- All DOE Office Websites (Extended Search)

Technetium Previous Element (Technetium) The Periodic Table of Elements Next Element (Rhodium) Rhodium Isotopes of the Element Ruthenium Click for Main Data Most of the isotope...

16

DNA-based asymmetric catalysis.  

E-Print Network (OSTI)

??The goal of the research described in this thesis was to develop the general concept and methodology of DNA-based asymmetric catalysis, with the aim of… (more)

Boersma, Arnold Jacob

2009-01-01T23:59:59.000Z

17

BNL | CFN: Interface Science & Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Interface Science & Catalysis Contact: Peter Sutter The world is facing unprecedented challenges in satisfying a rapidly growing demand for energy while reducing negative impacts...

18

Fuel Cell Technologies Office: Catalysis Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Catalysis Working Group to someone by E-mail Share Fuel Cell Technologies Office: Catalysis Working Group on Facebook Tweet about Fuel Cell Technologies Office: Catalysis Working Group on Twitter Bookmark Fuel Cell Technologies Office: Catalysis Working Group on Google Bookmark Fuel Cell Technologies Office: Catalysis Working Group on Delicious Rank Fuel Cell Technologies Office: Catalysis Working Group on Digg Find More places to share Fuel Cell Technologies Office: Catalysis Working Group on AddThis.com... Key Activities Plans, Implementation, & Results Accomplishments Organization Chart & Contacts Quick Links Hydrogen Production Hydrogen Delivery Hydrogen Storage Fuel Cells Technology Validation Manufacturing Codes & Standards Education Systems Analysis

19

Texture of atomic layer deposited ruthenium  

Science Conference Proceedings (OSTI)

Ruthenium films were grown by plasma enhanced atomic layer deposition (ALD) on Si(100) and ALD TiN. X-ray diffraction (XRD) showed that the as-deposited films on Si(100) were polycrystalline, on TiN they were (002) oriented. After annealing at 800^oC ... Keywords: Ammonia plasma, Atomic layer deposition, Ruthenium, Silicide, Texture

J. Musschoot; Q. Xie; D. Deduytsche; K. De Keyser; D. Longrie; J. Haemers; S. Van den Berghe; R. L. Van Meirhaeghe; J. D'Haen; C. Detavernier

2010-10-01T23:59:59.000Z

20

Textured Metal Catalysts for Heterogeneous Catalysis ...  

Biomass and Biofuels Advanced Materials Textured Metal Catalysts for Heterogeneous Catalysis Pacific Northwest National Laboratory. Contact ...

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Ruthenium-Platinum Thin Film Analysis Using Grazing Incidence X-ray Diffraction  

DOE Green Energy (OSTI)

Ruthenium (Ru, Z = 44) is a Platinum Group Metal that has a standard hexagonal close packed (HCP) crystalline structure. Platinum (Pt, Z = 78) has a face-centered cubic (FCC) crystalline structure. When these metals are co-sputtered onto a silicon substrate, creating a few nm-thin film, they form an alloy with a combination of HCP and FCC structure. Direct methanol fuel cells rely on an anode catalyst to draw hydrogen from liquid methanol. Highly efficient fuel cells based on polymer electrolyte catalysts, known as proton-exchange membrane fuel cells, have been developed, but require large amounts of a costly platinum catalyst. Thin-film nanostructure bimetallic alloys have been produced to reduce the amount of expensive Platinum needed for catalysis, and also to improve the electrochemical properties of the catalyst. Supported RuPt particles have been shown to have superior activity as anode catalysts for methanol electro-oxidation and demonstrate an improvement in resistance to poisoning in comparison to unalloyed Pt. The percentage of Ruthenium in a RuPt thin film and the process by which the alloy is produced will dictate the crystalline structure, and thus the electrochemical properties of the film. Pure Ruthenium, Pure Platinum, and eight intermediate samples at differing percent composition of Ruthenium were characterized by their X-ray diffraction patterns. The incident beam is from the Stanford Synchrotron Radiation Laboratory beam and operates at approximately a 1.4 Angstrom wavelength. The results show that 0% Ru through 46.17% Ru exhibit a majority FCC structure, 56.07% Ru and 60.61% Ru are mixed phase, and from 67.03% Ru through 100% Ru, the samples exhibit a HCP structure.

Jones, L.

2004-09-03T23:59:59.000Z

22

Molecular ingredients of heterogeneous catalysis  

Science Conference Proceedings (OSTI)

The purpose of this paper is to present a review and status report to those in theoretical chemistry of the rapidly developing surface science of heterogeneous catalysis. The art of catalysis is developing into science. This profound change provides one with opportunities not only to understand the molecular ingredients of important catalytic systems but also to develop new and improved catalyst. The participation of theorists to find answers to important questions is sorely needed for the sound development of the field. It is the authors hope that some of the outstanding problems of heterogeneous catalysis that are identified in this paper will be investigated. For this purpose the paper is divided into several sections. The brief Introduction to the methodology and recent results of the surface science of heterogeneous catalysis is followed by a review of the concepts of heterogeneous catalysis. Then, the experimental results that identified the three molecular ingredients of catalysis, structure, carbonaceous deposit and the oxidation state of surface atoms are described. Each section is closed with a summary and a list of problems that require theoretical and experimental scrutiny. Finally attempts to build new catalyst systems and the theoretical and experimental problems that appeared in the course of this research are described.

Somorjai, G.A.

1982-06-01T23:59:59.000Z

23

Enhanced Micellar Catalysis LDRD.  

SciTech Connect

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.

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

2012-12-01T23:59:59.000Z

24

Fuel Synthesis Catalysis Laboratory (Fact Sheet)  

DOE Green Energy (OSTI)

This fact sheet provides information about Fuel Synthesis Catalysis Laboratory capabilities and applications at NREL's National Bioenergy Center.

Not Available

2011-07-01T23:59:59.000Z

25

Fuel Synthesis Catalysis Laboratory (Fact Sheet)  

SciTech Connect

This fact sheet provides information about Fuel Synthesis Catalysis Laboratory capabilities and applications at NREL's National Bioenergy Center.

Not Available

2013-07-01T23:59:59.000Z

26

Argonne Chemical Sciences & Engineering - Publications - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

News & Highlights Events Search Argonne ... Search Argonne Home > Chemical Sciences & Engineering > Fundamental Interactions Catalysis & Energy Conversion Electrochemical...

27

Argonne Chemical Sciences & Engineering - People - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

News & Highlights Events Search Argonne ... Search Argonne Home > Chemical Sciences & Engineering > Fundamental Interactions Catalysis & Energy Conversion Electrochemical...

28

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

News & Highlights Events Search Argonne ... Search Argonne Home > Chemical Sciences & Engineering > Homogeneous Catalysis * Members * Contact * Publications * Research Projects...

29

Available Technologies: Nanocrystal Assembly for Tandem Catalysis  

APPLICATIONS OF TECHNOLOGY: Industrial catalysis; Development of artificial photosynthesis; Multiple-step chemical reactions ; ADVANTAGES: Enables reactions requiring ...

30

EMSL and Institute for Integrated Catalysis (IIC) Catalysis Workshop  

DOE Green Energy (OSTI)

Within the context of significantly accelerating scientific progress in research areas that address important societal problems, a workshop was held in November 2010 at EMSL to identify specific and topically important areas of research and capability needs in catalysis-related science.

Campbell, Charles T.; Datye, Abhaya K.; Henkelman, Graeme A.; Lobo, Raul F.; Schneider, William F.; Spicer, Leonard D.; Tysoe, Wilfred T.; Vohs, John M.; Baer, Donald R.; Hoyt, David W.; Thevuthasan, Suntharampillai; Mueller, Karl T.; Wang, Chong M.; Washton, Nancy M.; Lyubinetsky, Igor; Teller, Raymond G.; Andersen, Amity; Govind, Niranjan; Kowalski, Karol; Kabius, Bernd C.; Wang, Hongfei; Campbell, Allison A.; Shelton, William A.; Bylaska, Eric J.; Peden, Charles HF; Wang, Yong; King, David L.; Henderson, Michael A.; Rousseau, Roger J.; Szanyi, Janos; Dohnalek, Zdenek; Mei, Donghai; Garrett, Bruce C.; Ray, Douglas; Futrell, Jean H.; Laskin, Julia; DuBois, Daniel L.; Kuprat, Laura R.; Plata, Charity

2011-05-24T23:59:59.000Z

31

One-Pot Formation of Functionalized Indole and Benzofuran Derivatives Using a Single Bifunctional Ruthenium Catalyst  

E-Print Network (OSTI)

Bifunctional Ruthenium Catalyst Reji N. Nair • Paul J. Lee •bifunctional ruthenium catalyst for cyclization of terminalof transi- tion metal based catalysts have been reported to

Nair, Reji N.; Lee, Paul J.; Grotjahn, Douglas B.

2010-01-01T23:59:59.000Z

32

Catalysis on the Nanoscale: Preparation, Characterization and...  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis on the Nanoscale: Preparation, Characterization and Reactivity of Metal-Based Nanostructures The purpose of this program is to explore and manipulate the size, morphology...

33

Basic Research Needs: Catalysis for Energy  

DOE Green Energy (OSTI)

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.

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

2008-03-11T23:59:59.000Z

34

Resonant Polarized Radiation Catalysis, and the Expansion  

Science Conference Proceedings (OSTI)

Presentation Title, The Birth of a New Field of Materials Science: Resonant Polarized Radiation Catalysis, and the Expansion of Thermodynamics. Author(s)  ...

35

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

NLE Websites -- All DOE Office Websites (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...

36

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

* Fuel Quality Issues * Production of Hydrogen using Copper-Chlorine Cycle Catalysis & Energy Conversion Home Fuel Cell Engineering A bread-board apparatus was tested to study...

37

Iron catalysis in oxidation by ozone - Energy Innovation Portal  

Bookmark Iron catalysis in oxidation by ozone - Energy Innovation Portal on Google; Bookmark Iron catalysis in oxidation by ozone - Energy Innovation ...

38

PHOTOCHEMICAL CO2 REDUCTION BY RHENUIM AND RUTHENIUM COMPLEXES.  

DOE Green Energy (OSTI)

Photochemical conversion of CO{sub 2} to fuels or useful chemicals using renewable solar energy is an attractive solution to both the world's need for fuels and the reduction of greenhouse gases. Rhenium(I) and ruthenium(II) diimine complexes have been shown to act as photocatalysts and/or electrocatalysts for CO{sub 2} reduction to CO. We have studied these photochemical systems focusing on the identification of intermediates and the bond formation/cleavage reactions between the metal center and CO{sub 2}. For example, we have produced the one-electron-reduced monomer (i.e. Re(dmb)(CO){sub 3}S where dmb = 4,4'-dimethy-2,2'-bipyridine and S = solvent) either by reductive quenching of the excited states of fac-[Re(dmb)(CO){sub 3}(CH{sub 3}CN)]PF{sub 6} or by photo-induced homolysis of [Re(dmb)(CO){sub 3}]{sub 2}. We previously found that: (1) the remarkably slow dimerization of Re(dmb)(CO){sub 3}S is due to the absence of a vacant coordination site for Re-Re bond formation, and the extra electron is located on the dmb ligand; (2) the reaction of Re(dmb)(CO){sub 3}S with CO{sub 2} forms a CO{sub 2}-bridged binuclear species (CO){sub 3}(dmb)Re-CO(O)-Re(dmb)(CO){sub 3} as an intermediate in CO formation; and (3) the kinetics and mechanism of reactions are consistent with the interaction of the CO{sub 2}-bridged binuclear species with CO{sub 2} to form CO and CO{sub 3}{sup 2-}.

FUJITA,E.; MUCKERMAN, J.T.; TANAKA, K.

2007-11-30T23:59:59.000Z

39

DOE Laboratory Catalysis Research Symposium - Abstracts  

SciTech Connect

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.

Dunham, T.

1999-02-01T23:59:59.000Z

40

The biokinetics of ruthenium in the human body  

SciTech Connect

The biokinetics of ruthenium (Ru) in the human body is of interest due mainly to the potential for occupational or environmental exposure to 106Ru (T1/2 = 373.6 d) and 103Ru (T1/2 = 39.3 d), which typically represent a significant portion of the fission products in a reactor inventory. During reactor operations or nuclear fuel reprocessing these ruthenium isotopes may be present as ruthenium tetroxide (RuO4) vapor, a highly mobile form of ruthenium that has been involved in a number of cases of accidental exposure to 106Ru or 103Ru. This paper summarizes the biokinetic database for ruthenium and proposes a new respiratory model for inhaled RuO4 vapor, a new biokinetic for systemic (absorbed) ruthenium, and material-specific gastrointestinal absorption fractions for ruthenium. The proposed respiratory model for RuO4 differs from the current ICRP model mainly in that it depicts slower clearance of deposited activity from the respiratory tract and lower absorption to blood than depicted in the current ICRP model. The proposed systemic biokinetic model depicts more realistic paths of movement of absorbed ruthenium in the body than the current ICRP model and, in contrast to the present model, a less uniform distribution of systemic activity. Implications of the proposed models with regard to inhalation and ingestion dose coefficients for 106Ru are examined.

Leggett, Richard Wayne [ORNL

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Fischer-Tropsch synthesis process employing a moderated ruthenium catalyst  

DOE Patents (OSTI)

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.

Abrevaya, H.

1990-07-31T23:59:59.000Z

42

Fischer-Tropsch synthesis process employing a moderated ruthenium catalyst  

DOE Green Energy (OSTI)

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.

Abrevaya, Hayim (Wilmette, IL)

1990-01-01T23:59:59.000Z

43

"Nanocrystal bilayer for tandem catalysis"  

DOE Green Energy (OSTI)

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

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

2011-01-24T23:59:59.000Z

44

Surface science and heterogeneous catalysis  

DOE Green Energy (OSTI)

The catalytic reactions studied include hydrocarbon conversion over platinum, the transition metal-catalyzed hydrogenation of carbon monoxide, and the photocatalyzed dissociation of water over oxide surfaces. The method of combined surface science and catalytic studies is similar to those used in synthetic organic chemistry. The single-crystal models for the working catalyst are compared with real catalysts by comparing the rates of cyclopropane ring opening on platinum and the hydrogenation of carbon monoxide on rhodium single crystal surface with those on practical commercial catalyst systems. Excellent agreement was obtained for these reactions. This document reviews what was learned about heterogeneous catalysis from these surface science approaches over the past 15 years and present models of the active catalyst surface.

Somorjai, G.A.

1980-05-01T23:59:59.000Z

45

PROCESS FOR DECONTAMINATING THORIUM AND URANIUM WITH RESPECT TO RUTHENIUM  

DOE Patents (OSTI)

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.

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

1959-10-20T23:59:59.000Z

46

Cationic Ruthenium Catalysts for Olefin Hydrovinylation  

E-Print Network (OSTI)

Stereoselective carbon?carbon bond formation is one of the most important types of bond construction in organic chemistry. A mild and acid free catalyst system for the hydrovinylation reaction utilizing a cationic, ruthenium center is described. A catalytic amount of RuHCl(CO)(PCy3)2 (2) activated with AgOTF or AgSbF6 at room temperature was found to be an effective catalyst system for the hydrovinylation of vinylarenes and the intramolecular hydrovinylation (IHV) of 1,6-dienes. Vinylarenes with both electron-donating and electron-withdrawing substituents reacted with ethylene at room temperature to provide the desired 3-arylbutenes in moderate to excellent yield (60-99%) under mild reaction conditions, while the IHV reaction of 1, 6 dienes provided greater than 90% of product conversion. We also developed the first hydrovinylation catalyst containing a chelating, bidentate phosphine ligand that provides the desired product. Our ruthenium-based catalytic system has also proven to give an appealing reactivity profile in favor of the desired arylbutenes without promoting undesirable oligomerization and isomerization.

Sanchez, Richard P., Jr

2009-08-01T23:59:59.000Z

47

Nickel/ruthenium catalyst and method for aqueous phase reactions  

DOE Patents (OSTI)

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.

Elliott, Douglas C. (Richland, WA); Sealock, John L. (West Richland, WA)

1998-01-01T23:59:59.000Z

48

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

DOE Green Energy (OSTI)

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.

Peden, Charles HF.; Ray, Douglas

2005-10-05T23:59:59.000Z

49

Characterization of hydrous ruthenium oxide/carbon nanocomposite supercapacitors prepared by a colloidal method  

E-Print Network (OSTI)

Characterization of hydrous ruthenium oxide/carbon nanocomposite supercapacitors prepared reserved. Keywords: Colloidal method; Ruthenium oxide; Nanocomposite; Supercapacitors 1. Introduction indicated that composite Ru oxide-carbon based supercapacitors possess superior energy and power densities

Popov, Branko N.

50

Fuel Cell Technologies Office: Catalysis Working Group Kick-Off...  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Group Kick-Off Meeting: May 2012 to someone by E-mail Share Fuel Cell Technologies Office: Catalysis Working Group Kick-Off Meeting: May 2012 on Facebook Tweet...

51

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

NLE Websites -- All DOE Office Websites (Extended Search)

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...

52

Iron Catalysis in Oxidations by Ozone - Energy Innovation Portal  

Wind Energy; Partners (27) Visual Patent Search; Success Stories; News; Events; Industrial Technologies Iron Catalysis in Oxidations by Ozone Ames ...

53

Nucleation Catalysis Potency of Ceramic Nanoparticles in Aluminum ...  

Science Conference Proceedings (OSTI)

Symposium, Frontiers in Solidification Science. Presentation Title, Nucleation Catalysis Potency of Ceramic Nanoparticles in Aluminum Matrix Nanocomposites .

54

Rubidium dimers in paraffin-coated cells  

E-Print Network (OSTI)

Measurements were made to determine the density of rubidium dimer vapor in paraffin-coated cells. The number density of dimers and atoms in similar paraffin-coated and uncoated cells was measured by optical spectroscopy. Due to the relatively low melting point of paraffin, a limited temperature range of 43-80 deg C was explored, with the lower end corresponding to a dimer density of less than 10^7 cm^(-3). With one-minute integration time, a sensitivity to dimer number density of better than 10^6 cm^(-3) was achieved. No significant difference in dimer density was observed between the cells.

V. M. Acosta; A. Jarmola; D. Windes; E. Corsini; M. P. Ledbetter; T. Karaulanov; M. Auzinsh; S. A. Rangwala; D. F. Jackson Kimball; D. Budker

2010-05-03T23:59:59.000Z

55

Fuel Cell Technologies Office: Catalysis Working Group  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Working Group Catalysis Working Group The 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 investigators in electrocatalysis projects funded by the U.S. Department of Energy (DOE), as well as supporting DOE personnel. More information on DOE electrocatalysis activities can be found in the Multi-Year Research, Development, and Demonstration Plan.

56

Opportunities in Catalysis Research Using Synchrotron Radiation  

NLE Websites -- All DOE Office Websites (Extended Search)

in Catalysis Research Using Synchrotron Radiation 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: Anders Nilsson 3:45-4:15 Lars Pettersson Stockholm University Adsorbate-Substrate Bonding: An Experimental and Theoretical MO Picture 4:15-4:45 Miquel Salmeron Lawrence Berkeley National Laboratory Photoelectron Spectroscopy studies of surfaces in high pressure gas

57

Catalysis: Reactivity and Structure Group | Chemistry Department |  

NLE Websites -- All DOE Office Websites (Extended Search)

Group Members Group Members Principal Investigators Jose Rodriguez Catalysis and surface science. Interaction and reaction of molecules with surfaces of metals, oxides, sulfides and carbides. Use of synchrotron-based techniques in surface and materials characterization (core and valence photoemission, x-ray absorption spectroscopy, x-ray diffraction). Modeling of surface reactions. Ping Liu Theoretical description of nanostructures, supported nanostructures, surfaces and their catalytic applications in heterogeneous catalysis and electrocatalysis. Density functional calculations, kinetic modeling and sensitivity analysis are employed to obtain a fundamental understanding of catalytic processes Dario Stacchiola Nano-Catalysis, Model mixed metal oxides, In-situ catalytic reactions at ambient pressures (AP). (Synchrotron PES, AP-XPS, AP-STM, AP-IRRAS, Inverse Catalyst, Nanoparticles, Graphene)

58

Fiber optic D dimer biosensor  

DOE Patents (OSTI)

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.

Glass, Robert S. (Livermore, CA); Grant, Sheila A. (Pleasanton, CA)

1999-01-01T23:59:59.000Z

59

Holographic lattices, dimers, and glasses  

Science Conference Proceedings (OSTI)

We holographically engineer a periodic lattice of localized fermionic impurities within a plasma medium by putting an array of probe D5-branes in the background produced by N D3-branes. Thermodynamic quantities are computed in the large N limit via the holographic dictionary. We then dope the lattice by replacing some of the D5-branes by anti-D5-branes. In the large N limit, we determine the critical temperature below which the system dimerizes with bond ordering. Finally, we argue that for the special case of a square lattice our system is glassy at large but finite N, with the low temperature physics dominated by a huge collection of metastable dimerized configurations without long-range order, connected only through tunneling events.

Kachru, Shamit; Karch, Andreas; Yaida, Sho [Kavli Institute for Theoretical Physics and Department of Physics, University of California, Santa Barbara, California 93106 (United States); Department of Physics, University of Washington, Seattle, Washington 98195-1560 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States)

2010-01-15T23:59:59.000Z

60

A Very Short Ruthenium(II) - Nitrogen Heterocycle Bond  

NLE Websites -- All DOE Office Websites (Extended Search)

Very Short Ruthenium(II) - Nitrogen Heterocycle Bond: The Crystal Very Short Ruthenium(II) - Nitrogen Heterocycle Bond: The Crystal Structures of Pentaammine(N-methylpyrazinium)ruthenium(II) Iodide and Pentaammine(N-methylpyrazinium)ruthenium(III) p-Toluenesulfonate Pentahydrate James F. Wishart, Avi Bino and Henry Taube Inorg. Chem. 25, 3318-3321 (1986) Abstract: The crystal structures of [(NH3)5Ru(NC4H4NCH3)] I3 and [(NH3)5Ru(NC4H4NCH3)] (CH3C6H4SO3)4°5H2O have been solved to weighted R factors of 0.053 and 0.083, respectively. For the former structure, the space group is Pmma with a = 10.655(2)Å, b = 7.704(1)Å, c = 21.488(3)Å, and Z = 4. The Ru(II)-N(Mepyz) distance of 1.95(1)Å in this complex is the shortest yet reported for a ruthenium(II) to heteroctclic nitrogen bond. A difference of 0.04(1)Å between the cis (2.122(7)Å and 2.136(8)Å) and

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While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
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61

Plenary lecture 2: nanotechnology and heterogeneous catalysis  

Science Conference Proceedings (OSTI)

Catalysis is the process in which the rate of a chemical reaction is increased by means of a chemical substance known as a catalyst. Catalysts can be either heterogeneous or homogeneous, depending on whether a catalyst exists in the same phase as the ...

Karim H. Hassan

2009-02-01T23:59:59.000Z

62

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

Office of Science (SC) Website

Catalysis Catalysis Basic Energy Sciences Advisory Committee (BESAC) BESAC Home Meetings Meeting Presentations History Logistics Members Charges/Reports Charter .pdf file (41KB) BES Committees of Visitors BES Home Meetings Catalysis Print Text Size: A A A RSS Feeds FeedbackShare Page Tuesday, May 14, 2002 - Opening Plenary Session Catalysis and Nanoscience Activities in BES - William Millman Energy Generation, Carbon Mgmt., and Methodology - John Frost Nanoscience and Catalysis - D. Wayne Goodman Wednesday, May 15, 2002 - 2nd Day Plenary Session Heterogeneous Catalysis - J. K. Norskov Homogeneous and Single-Site Heterogeneous Catalysis - Tobin Marks Thursday, May 16, 2002 - Breakout Summary Reports Catalysts Design Driven by Fundamental Research - Barteau Linking Basic Research to Applications - Bare Bell

63

The Reactivity Limit for Methanol Oxidation on Platinum/Ruthenium...  

NLE Websites -- All DOE Office Websites (Extended Search)

"Catalysis and Electrocatalysis at Nanoparticle Surfaces", M. Dekker Inc., N. York, Basel, 2003 (ISBN: 0-8247-0879-2), pp. 1-970. * J. Catal., priority comm., 203, 1 (2001). *...

64

Synthesis and Characterization of Hydrous Ruthenium Oxide-Carbon Supercapacitors  

E-Print Network (OSTI)

Synthesis and Characterization of Hydrous Ruthenium Oxide-Carbon Supercapacitors Manikandan Ramani It is shown that composite Ru oxide-carbon based supercapacitors possess superior energy and power densities. Electrochemical capacitors or supercapacitors are novel power devices, which lie between batteries

Popov, Branko N.

65

USD Catalysis Group for Alternative Energy  

DOE Green Energy (OSTI)

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.

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

2012-03-13T23:59:59.000Z

66

Nanoscale Advances in Catalysis and Energy Applications  

SciTech Connect

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.

Li, Yimin; Somorjai, Gabor A.

2010-05-12T23:59:59.000Z

67

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

Science Conference Proceedings (OSTI)

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.

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

2011-10-01T23:59:59.000Z

68

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

NLE Websites -- All DOE Office Websites (Extended Search)

for propylene epoxidation. Larry Curtiss Materials Design and Discovery: Catalysis and Energy Storage PI Name: Larry Curtiss PI Email: curtiss@anl.gov Institution: Argonne...

69

Workshop on Catalysis Research at the Advanced Photon Source  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalysis Workshop Home Program Registration Poster Registration Organizing Committee: * Chris Marshall (ANL) * Peter Stair (NWU) * Simon Bare (UOP) * Hoydoo You (ANL) * Randy...

70

Application of Alum from Kankara Kaolinite in Catalysis  

Science Conference Proceedings (OSTI)

Presentation Title, Application of Alum from Kankara Kaolinite in Catalysis: A Preliminary Report. Author(s), Lawrence Chukwuka Edomwonyi-Otu, Benjamin ...

71

THE MECHANISM AND KINETICS OF FISCHER-TROPSCH SYNTHESIS OVER SUPPORTED RUTHENIUM CATALYSTS  

E-Print Network (OSTI)

Structure of Metallic Catalysts", Academic Press Inc. , Newselectivity of these catalysts. Several appendices dealingOver Supported Ruthenium Catalysts ABSTRACT The effects of

Kellner, Carl Stephen

2013-01-01T23:59:59.000Z

72

Structure sensitive adsorption of hydrogen on ruthenium and ruthenium-silver catalysts supported on silica  

DOE Green Energy (OSTI)

Supported metal catalysts typically consist of particles with sizes less than 10 nm, and because of the small crystallite size, low coordination number sites (edges and corners) represent a significant fraction of all surface sites. Furthermore, it has been demonstrated that adsorption rates can be much greater at these low coordination sites than on basal plane sites. What has not been generally appreciated, however, is that preferential adsorption at edge and corner sites may explain the mechanism by which a promoter, or the addition of a second metal to form a bimetallic, can alter the selectivity and rate of reaction. For example, the measurements of hydrogen adsorption onto supported Ru-Ag catalysts show marked decreases in the amount of hydrogen adsorbed relative to the amount adsorbed on Ru catalysts. Although it is known that Ag does not dissociatively adsorb hydrogen, this decrease cannot be explained by a simple one-to-one site blocking mechanism unless Ag preferentially populates edges and corners, thereby reducing the number of Ru edge sites. Indeed, Monte Carlo simulations of Ru-Group IB metal catalysts predict that Group IB metal atoms preferentially populate corner and edge sites of ruthenium crystals. This evidence, taken together, suggests that adsorption occurs preferentially at Ru corner and edge sites, which act as portals onto basal planes. A model based on this portal theory for hydrogen adsorption onto supported ruthenium bimetallic catalysts has been developed using a rate equation approach. Specifically, the model accounts for the following features: (1) preferential adsorption through portals, (2) basal plane site-energy multiplicity, and (3) hydrogen spillover onto the support. A comparison of model predictions with experiment is presented for different concentration of Ag in Ru-Ag catalysts. The portal model of hydrogen adsorption can explain the observed decreased in the amount of hydrogen adsorbed on Ru-Ag catalysts. The model can be applied to understand the kinetics of ethane hydrogenolysis on Ru-Ag catalysts. The model is able to explain the change in the apparent order of hydrogenolysis reaction with respect to hydrogen from {minus}1.4 to {minus}2.4 when Ag is added to Ru/SiO{sub 2} catalyst.

Kumar, N.

1999-02-12T23:59:59.000Z

73

Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands  

E-Print Network (OSTI)

Lithium Diisopropylamide-Mediated Enolization: Catalysis by Hemilabile Ligands Antonio Ramirez of a lithium diisopropylamide (LDA)-mediated ester enolization. Hemilabile amino ether MeOCH2CH2NMe2, binding-based catalysis are thwarted by the occlusion of the catalyst on the lithium salt products and byproducts (eq 1

Collum, David B.

74

Ruthenium Bisbipyridine Complexes of Horse Heart Cytochrome c  

NLE Websites -- All DOE Office Websites (Extended Search)

Ruthenium Bisbipyridine Complexes of Horse Heart Cytochrome c: Ruthenium Bisbipyridine Complexes of Horse Heart Cytochrome c: Characterization and Comparative Intramolecular Electron Transfer Rates Determined by Pulse Radiolysis and Flash Photolysis J. Luo, K. B. Reddy, A. S. Salameh, J. F. Wishart and S. S. Isied Inorg. Chem. 39, 2321-2329 (2000) [Find paper at ACS Publications] Abstract: The reaction of [Ru(bpy)2L(H2O)]2+ (bpy = 2,2'-bipyridine, L = imidazole, water) with reduced horse heart cytochrome c results in coordination of [RuII(bpy)2L] at the His 33 and His 26 sites. Coordination at the His 33 site gave a diastereomeric [RuII(bpy)2L]-His-cyt c (II) mixture favoring the L-Ru form regardless of the substituent on the bipyridine ligands, while substitution at the more buried His 26 site gave isomeric distribution that varies according to the substituent on the bipyridine

75

Complex of transferrin with ruthenium for medical applications  

DOE Patents (OSTI)

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.

Richards, Powell (Bayport, NY); Srivastava, Suresh C. (Setauket, NY); Meinken, George E. (Middle Island, NY)

1984-05-15T23:59:59.000Z

76

Hydrogen and oxygen adsorption stoichiometries on silica supported ruthenium nanoparticles  

DOE Green Energy (OSTI)

Treatment under H{sub 2} at 300 C of Ru(COD)(COT) dispersed on silica yields 2 nm ruthenium nanoparticles, [Ru{sub p}/SiO{sub 2}], according to EXAFS, HRTEM and XPS. H{sub 2} adsorption measurements on [Ru{sub p}/SiO{sub 2}] in the absence of O{sub 2} show that Ru particles adsorb up to ca. 2 H per surface ruthenium atoms (2H/Ru{sub s}) on various samples; this technique can therefore be used to measure the dispersion of Ru particles. In contrast, O{sub 2} adsorption on [Ru{sub p}/SiO{sub 2}] leads to a partial oxidation of the bulk at 25 C, to RuO{sub 2} at 200 C and to sintering upon further reduction under H{sub 2}, showing that O{sub 2} adsorption cannot be used to measure the dispersion of Ru particles.

Berthoud, Romain; Delichere, Pierre; Gajan, David; Lukens, Wayne; Pelzer, Katrin; Basset, Jean-Marie; Candy, Jean-Pierre; Coperet, Christophe

2008-12-01T23:59:59.000Z

77

Stereoselective Binding of Ruthenium Complexes to Cytochrome c  

NLE Websites -- All DOE Office Websites (Extended Search)

Site-Dependent Stereoselective Binding of Ruthenium Aquobipyridine Site-Dependent Stereoselective Binding of Ruthenium Aquobipyridine Complexes to Histidine Side Chains in Horse Heart Cytochrome c Jian Luo, James F. Wishart, and Stephan S. Isied J. Am. Chem. Soc. 120, 12970-12971 (1998) [Find paper at ACS Publications] Abstract: Stereoselective covalent binding of the ruthenium complexes cis-[Ru(bpy)2(H2O)2]2+ (bpy = 2,2'-bipyridine) and cis-[Ru(dmbpy)2(H2O)2]2+ (dmbpy = 4,4'-dimethyl-2,2'-bipyridine) to the surface His 33 residue and the more buried His 26 residues of Horse heart cytochrome c (Hh cyt c) to form large enantiomeric excess of D-[Ru(dmbpy)2(H2O)]-His 26-cyt c (38%), but little or no excess of D-[Ru(bpy)2(H2O)]-His 26-cyt c (6%). At the surface exposed His 33 site, equal entiomeric excess of L-[Ru(dmbpy)2(H2O)]-His 33-cyt c and L-[Ru(bpy)2(H2O)]-His 33-cyt c (34%)

78

Factors determining the consumption of ruthenium during electrosynthesis of sodium hypochlorite with the use of ruthenium oxide-titanium anodes  

Science Conference Proceedings (OSTI)

The authors studied the rate of destruction of the active coating as a function of the electrolysis conditions during electrochemical production of sodium hypochlorite. Corrosion tests were carried out on specimens made by the thermochemical method, in an electrochemical cell without a diaphragm; the method used was based on neutron activation analysis. It was shown that losses of ruthenium can be lowered by conducting the electrolysis at low temperatures, higher current densities, and moderately low hypochlorite concentrations. However, the increase of current density may raise the ROTA potential above the critical value, when rapid anode failure is possible. It was also shown that under conditions such that the critical ROTA potential is not reached sodium hypochlorite solutions of fairly high concentrations can be obtained with a low comsumption of ruthenium, which is not possible with the use of many other anode materials.

Klement'eva, V.S.; Kubasov, V.L.; Lambrev, V.G.; Uzbekov, A.A.

1985-09-01T23:59:59.000Z

79

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

Office of Science (SC) Website

Catalysis Science Catalysis Science Chemical Sciences, Geosciences, & Biosciences (CSGB) Division CSGB Home About Research Areas Energy Frontier Research Centers (EFRCs) DOE Energy Innovation Hubs Scientific Highlights Reports & Activities Principal Investigators' Meetings BES Home Research Areas Catalysis Science Print Text Size: A A A RSS Feeds FeedbackShare Page This research area develops the fundamental scientific principles enabling rational catalyst design and chemical transformation control. Research includes the identification of the elementary steps of catalytic reaction mechanisms and their kinetics; construction of catalytic sites at the atomic level; synthesis of ligands, metal clusters, and bio-inspired reaction centers designed to tune molecular-level catalytic activity and

80

Instrumentation @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

Instrumentation Instrumentation The Catalysis Group at BNL is leading research initiatives into the development of new tools and techniques that focus on the characterization of heterogeneous catalytic reactions and catalysts using imaging, spectroscopy and scattering techniques and integrated combinations of them under reaction conditions to unravel the morphology, chemical and structural properties, of catalysts, respectively. These efforts revolve around the use of synchrotron radiation (NSLS), electrons (CFN) and quantum tunneling tools with particular thrusts into imaging, spectroscopy and scattering. Groups Instrumentation(BNL) Three UHV chambers with diverse instrumentation for surface characterization: LEED, UPS, XPS, AES, TPD, ISS, PM-AP-IRRAS, Reactivity Cell. All the systems include ancillary instrumentation such as sputtering guns and metal evaporators. The IRRAS system was retrofitted with an ambient pressure (AP) cell on top of the UHV system. The sample can be prepared and characterized in UHV and then transfer in vacuum to the AP cell.

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsource  

NLE Websites -- All DOE Office Websites (Extended Search)

Shining Light on Catalysis 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 penetration depth of hard X-rays, in situ or operando experiments are possible. In addition, complementary techniques, such as the vibrational spectroscopies can be simultaneously applied. Recent development in instrumentation to perform quick EXAFS and secondary emission spectroscopy has provided exciting new opportunities to

82

Workflow for Tandem Catalysis in Nanocrystal Interfaces | Department...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View Edit Workflow(active tab) Current Revision Status published Revision 17905 Drafts ID Title Status Last Updated...

83

Theoretical investigation of solar energy conversion and water oxidation catalysis  

E-Print Network (OSTI)

Solar energy conversion and water oxidation catalysis are two great scientific and engineering challenges that will play pivotal roles in a future sustainable energy economy. In this work, I apply electronic structure ...

Wang, Lee-Ping

2011-01-01T23:59:59.000Z

84

Deposition of ruthenium nanoparticles on carbon aerogels for high energy density supercapacitor electrodes  

SciTech Connect

The preparation and characterization of high surface area ruthenium/carbon aerogel composite electrodes for use in electrochemical capacitors is reported. These new materials have been prepared by the chemical vapor impregnation of ruthenium into carbon aerogels to produce a uniform distribution of adherent {approx}20 {angstrom} nanoparticles on the aerogel surface. The electrochemically oxidized ruthenium particles contribute a pseudocapacitance to the electrode and dramatically improve the energy storage characteristics of the aerogel. These composites have demonstrated specific capacitances in excess of 200 F/g, in comparison to 95 F/g for the untreated aerogel.

Miller, J.M.; Dunn, B. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering; Tran, T.D.; Pekala, R.W. [Lawrence Livermore National Labs., CA (United States). Chemical Sciences Div.

1997-12-01T23:59:59.000Z

85

On the asymptotics of dimers on tori  

E-Print Network (OSTI)

We study asymptotics of the dimer model on large toric graphs. Let L be a weighted Z^2-periodic planar graph, and let W be a large-index sublattice of Z^2. For L bipartite we show that the dimer partition function on the quotient L/W has the asymptotic expansion exp[A f_0 + fsc + o(1)], where A is the area of L/W, f_0 is the free energy density in the bulk, and fsc is a finite-size correction term depending only on the conformal shape of the domain together with some parity-type information. Assuming a conjectural condition on the zero locus of the dimer characteristic polynomial, we show that an analogous expansion holds for L non-bipartite. The functional form of the finite-size correction differs between the two classes, but is universal within each class. Our calculations yield new information concerning the distribution of the number of loops winding around the torus in the associated double-dimer models.

Richard W. Kenyon; Nike Sun; David B. Wilson

2013-10-09T23:59:59.000Z

86

Publications @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

List of Publications since 2010 List of Publications since 2010 2013 "Unique properties of ceria nanoparticles supported on metals: Novel inverse ceria/copper catalysts for CO oxidation and the water-gas shift reaction" Senanayake, S.D., Stacchiola, D., and Rodriguez, J.A. Accounts of Chemical Research, 2013. 46(8): p. 1702-1711. "Characterization of metal-oxide catalysts in operando conditions by combining x-ray absorption and raman spectroscopies in the same experiment" Patlolla, A., Baumann, P., Xu, W., Senanayake, S.D., Rodriguez, J.A., and Frenkel, A.I. Topics in Catalysis, 2013. 56(11): p. 896-904. "In situ time-resolved x-ray diffraction study of the synthesis of Mo2C with different carburization agents" Guzman, H.J., Xu, W.Q., Stacchiola, D., Vitale, G., Scott, C.E., Rodriguez, J.A., and Pereira-Almao, P. Canadian Journal of Chemistry-Revue Canadienne De Chimie, 2013. 91(7): p. 573-582.

87

Some General Themes in Catalysis at LANL  

DOE Green Energy (OSTI)

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.

Gordon, John C. [Los Alamos National Laboratory

2012-07-19T23:59:59.000Z

88

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

DOE Patents (OSTI)

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.

Pierantozzi, Ronald (Macungie, PA)

1985-01-01T23:59:59.000Z

89

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

DOE Patents (OSTI)

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.

Gorer, Alexander (Sunnyvale, CA)

2002-01-01T23:59:59.000Z

90

On the Acid-Base Mechanism for Ruthenium Water Oxidation Catalysts  

E-Print Network (OSTI)

We present a detailed theoretical study of the pathway for water oxidation in synthetic ruthenium-based catalysts. As a first step, we consider a recently discovered single center catalyst, where experimental observations ...

Wang, Lee-Ping

91

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

DOE Patents (OSTI)

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.

Pierantozzi, R.

1985-04-02T23:59:59.000Z

92

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

DOE Patents (OSTI)

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.

Pierantozzi, R.

1985-04-09T23:59:59.000Z

93

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

DOE Patents (OSTI)

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.

Elliot, Douglas C. (Richland, WA); Werpy, Todd A. (West Richland, WA); Wang, Yong (Richland, WA); Frye, Jr., John G. (Richland, WA)

2001-01-01T23:59:59.000Z

94

Substituents Dependent Capability of bis(ruthenium-dioxolene-terpyridine)Complexes Toward Water Oxidation  

Science Conference Proceedings (OSTI)

The bridging ligand, 1,8-bis(2,2':6',2{double_prime}-terpyrid-4'-yl)anthracene (btpyan) was synthesized by the Miyaura-Suzuki cross coupling reaction of anthracenyl-1,8-diboronic acid and 4'-triflyl-2,2':6'-2{double_prime}-terpyridine in the presence of Pd(PPh{sub 3}){sub 4} (5 mol%) with 68% in yield. Three ruthenium-dioxolene dimers, [Ru{sub 2}(OH){sub 2}(dioxolene){sub 2}(btpyan)]{sup 0} (dioxolene = 3,6-di-tert-butyl-1,2-benzosemiquinone ([1]{sup 0}), 3,5-dichloro-1,2-benzosemiquinone ([2]{sup 0}) and 4-nitro-1,2-benzosemiquinone ([3]{sup 0})) were prepared by the reaction of [Ru{sub 2}Cl{sub 6}(btpyan)]{sup 0} with the corresponding catechol. The electronic structure of [1]{sup 0} is approximated by [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} (sq = semiquinonato). On the other hand, the electronic states of [2]{sup 0} and [3]{sup 0} are close to [Ru{sub 2}{sup III}(OH){sub 2} (cat){sub 2}(btpyan)]{sup 0} (cat = catecholato), indicating that a dioxolene having electron-withdrawing groups stabilizes [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0} rather than [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} as resonance isomers. No sign was found of deprotonation of the hydroxo groups of [1]{sup 0}, whereas [2]{sup 0} and [3]{sup 0} showed an acid-base equilibrium in treatments with t-BuOLi followed by HClO{sub 4}. Furthermore, controlled potential electrolysis of [1]{sup 0} deposited on an ITO (indium-tin oxide) electrode catalyzed the four-electron oxidation of H{sub 2}O to evolve O{sub 2} at potentials more positive than +1.6 V (vs. SCE) at pH 4.0. On the other hand, the electrolysis of [2]{sup 0} and [3]{sup 0} deposited on ITO electrodes did not show catalytic activity for water oxidation under similar conditions. Such a difference in the reactivity among [1]{sup 0}, [2]{sup 0} and [3]{sup 0} is ascribed to the shift of the resonance equilibrium between [Ru{sub 2}{sup II}(OH){sub 2}(sq){sub 2}(btpyan)]{sup 0} and [Ru{sub 2}{sup III}(OH){sub 2}(cat){sub 2}(btpyan)]{sup 0}.

Wada, T.; Muckerman, J.; Fujita, E.; Tanaka, K.

2010-12-23T23:59:59.000Z

95

Exhaust aftertreatment using plasma-assisted catalysis  

DOE Green Energy (OSTI)

In the field of catalysis, one application that has been classified as a breakthrough technology is the catalytic reduction of NO{sub x} in oxygen-rich environments using hydrocarbons. This breakthrough will require dramatic improvements in both catalyst and engine technology, but the benefits will be substantial for energy efficiency and a cleaner environment. Engine and automobile companies are placing greater emphasis on the diesel engine because of its potential for saving fuel resources and reducing CO{sub 2} emissions. The modern direct-injection diesel engine offers demonstrated fuel economy advantages unmatched by any other commercially-viable engine. The main drawback of diesel engines is exhaust emissions. A modification of existing oxidation catalyst/engine technology is being used to address the CO, hydrocarbon and particulates. However, no satisfactory solution currently exists for NO{sub x}. Diesel engines operate under net oxidizing conditions, thus rendering conventional three-way catalytic converters ineffective for the controlling the NO{sub x} emission. NO{sub x} reduction catalysts, using ammonia as a reductant, do exist for oxygen-rich exhausts; however, for transportation applications, the use of on-board hydrocarbon fuels is a more feasible, cost-effective, and environmentally-sound approach. Selective catalytic reduction (SCR) by hydrocarbons is one of the leading catalytic aftertreatment technologies for the reduction of NO{sub x} in lean-burn engine exhaust (often referred to as lean-NO{sub x}). The objective is to chemically reduce the pollutant molecules of NO{sub x} to benign molecules such as N{sub 2}. Aftertreatment schemes have focused a great deal on the reduction of NO because the NO{sub x} in engine exhaust is composed primarily of NO. Recent studies, however, have shown that the oxidation of NO to NO{sub 2} serves an important role in enhancing the efficiency for reduction of NO{sub x} to N{sub 2}. It has become apparent that preconverting NO to NO{sub 2} could improve both the efficiency and durability of lean-NO{sub x} catalysts. A non-thermal plasma is an efficient means for selective partial oxidation of NO to NO{sub 2}. The use of a non-thermal plasma in combination with a lean-NO{sub x} catalyst opens the opportunity for catalysts that are more efficient and more durable compared to conventional catalysts. In the absence of hydrocarbons, the O radicals will oxidize NO to NO{sub 2}, and the OH radicals will further oxidize NO{sub 2} to nitric acid. In plasma-assisted catalysis it is important that the plasma oxidize NO to NO{sub 2} without further producing acids.

Penetrante, B

2000-01-20T23:59:59.000Z

96

Center for Catalysis at Iowa State University  

Science Conference Proceedings (OSTI)

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)

Kraus, George A.

2006-10-17T23:59:59.000Z

97

High-Spin Cobalt Hydrides for Catalysis  

SciTech Connect

Organometallic chemists have traditionally used catalysts with strong-field ligands that give low-spin complexes. However, complexes with a weak ligand field have weaker bonds and lower barriers to geometric changes, suggesting that they may lead to more rapid catalytic reactions. Developing our understanding of high-spin complexes requires the use of a broader range of spectroscopic techniques, but has the promise of changing the mechanism and/or selectivity of known catalytic reactions. These changes may enable the more efficient utilization of chemical resources. A special advantage of cobalt and iron catalysts is that the metals are more abundant and cheaper than those currently used for major industrial processes that convert unsaturated organic molecules and biofeedstocks into useful chemicals. This project specifically evaluated the potential of high-spin cobalt complexes for small-molecule reactions for bond rearrangement and cleavage reactions relevant to hydrocarbon transformations. We have learned that many of these reactions proceed through crossing to different spin states: for example, high-spin complexes can flip one electron spin to access a lower-energy reaction pathway for beta-hydride elimination. This reaction enables new, selective olefin isomerization catalysis. The high-spin cobalt complexes also cleave the C-O bond of CO2 and the C-F bonds of fluoroarenes. In each case, the detailed mechanism of the reaction has been determined. Importantly, we have discovered that the cobalt catalysts described here give distinctive selectivities that are better than known catalysts. These selectivities come from a synergy between supporting ligand design and electronic control of the spin-state crossing in the reactions.

Holland, Patrick L. [Yale University] [Yale University

2013-08-29T23:59:59.000Z

98

Catalysis-by-design impacts assessment  

SciTech Connect

Catalyst researchers have always recognized the need to develop a detailed understanding of the mechanisms of catalytic processes, and have hoped that it would lead to developing a theoretical predictive base to guide the search for new catalysts. This understanding allows one to develop a set of hierarchical models, from fundamental atomic-level ab-initio models to detailed engineering simulations of reactor systems, to direct the search for optimized, efficient catalyst systems. During the last two decades, the explosions of advanced surface analysis techniques have helped considerably to develop the building blocks for understanding various catalytic reactions. An effort to couple these theoretical and experimental advances to develop a set of hierarchical models to predict the nature of catalytic materials is a program entitled Catalysis-by-Design (CRD).'' In assessing the potential impacts of CBD on US industry, the key point to remember is that the value of the program lies in developing a novel methodology to search for new catalyst systems. Industrial researchers can then use this methodology to develop proprietary catalysts. Most companies involved in catalyst R D have two types of ongoing projects. The first type, what we call market-driven R D,'' are projects that support and improve upon a company's existing product lines. Project of the second type, technology-driven R D,'' are longer term, involve the development of totally new catalysts, and are initiated through scientists' research ideas. The CBD approach will impact both types of projects. However, this analysis indicates that the near-term impacts will be on market-driven'' projects. The conclusions and recommendations presented in this report were obtained by the authors through personal interviews with individuals involved in a variety of industrial catalyst development programs and through the three CBD workshops held in the summer of 1989. 34 refs., 7 figs., 7 tabs.

Fassbender, L L; Young, J K [Pacific Northwest Lab., Richland, WA (USA); Sen, R K [Sen (R.K.) and Associates, Washington, DC (USA)

1991-05-01T23:59:59.000Z

99

Theoretical Study on Catalysis by Protein Enzymes and Ribozyme  

NLE Websites -- All DOE Office Websites (Extended Search)

Theoretical Study on 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 presence of His95 in the active site. Principal Investigator: Martin Karplus, Harvard University Research Objectives The goal of this project is to develop a greater understanding of the mechanisms involved in enzyme catalysis and related protein functions. We are studying two types of enzymes: proteins and a nucleic acid (hammerhead

100

PNNL: Institute for Integrated Catalysis (IIC) at Pacific Northwest  

NLE Websites -- All DOE Office Websites (Extended Search)

Institute for Integrated Catalysis Institute for Integrated Catalysis The Institute for Integrated Catalysis at Pacific Northwest National Laboratory facilitates collaborative research and development in catalysts for a secure energy future. Latest Announcements When Less Is More: Fewer Proton Relays Improve Catalytic Rates First direct comparison of three nickel-based complexes shows complexes with 2 proton relays outperform those with 4 (January 2014) Wind and other renewable energy sources are limited because the power must be used when it's generated, as it currently cannot be stored. Scientists want to store the energy in compact, easy-to-release chemical bonds. A major challenge is designing an affordable, efficient, and fast catalyst to make the chemical bonds. At the Center for Molecular Electrocatalysis,

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101

Tandem Catalysis in Nanocrystal Interfaces | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Tandem Catalysis in Nanocrystal Interfaces Tandem Catalysis in Nanocrystal Interfaces Tandem Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View(active tab) Edit Workflow Addthis A unique new bilayer nanocatalyst system. | Image courtesy of Yang group A unique new bilayer nanocatalyst system. | Image courtesy of Yang group What does this mean for me? A prime example of these applications is artificial photosynthesis -- the effort to capture energy from the sun and transform it into electricity or chemical fuels. Catalysts (substances that speed up the rates of chemical reactions without themselves being chemically changed) are used to initiate virtually every industrial manufacturing process that involves chemistry. With the advent of nano-sized catalysts, metal and metal oxide catalysts have surged in

102

Jeffrey T. Miller Wins Award for Excellence in Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

van Veenendaal of X-ray Science Division wins 2009 NIU Presidential van Veenendaal of X-ray Science Division wins 2009 NIU Presidential Research Professorship 2009 APSUO Compton Award to Grübel, Mochrie, and Sutton New Era of Research Begins as World's First Hard X-ray Laser Achieves "First Light" Unique Uranium Source in Naturally Bioreduced Sediment Jonathan Lang Named 2008 PSC Supervisor of the Year APS News Archives: 2012 | 2011 | 2010 | 2009 2008 | 2007 | 2006 | 2005 2004 | 2003 | 2002 | 2001 2000 Subscribe to APS News rss feed Jeffrey T. Miller Wins Award for Excellence in Catalysis JUNE 15, 2009 Bookmark and Share Jeffrey T. Miller Jeffrey T. Miller, leader of the Heterogeneous Catalysis Group in the Argonne National Laboratory Chemical Sciences and Engineering Division (CSE), has been presented with the 2009 Award for Excellence in Catalysis

103

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

Science Conference Proceedings (OSTI)

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)

Not Available

1990-03-01T23:59:59.000Z

104

Size Effect of Ruthenium Nanoparticles in Catalytic Carbon Monoxide Oxidation  

Science Conference Proceedings (OSTI)

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.

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

2010-04-04T23:59:59.000Z

105

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

DOE Green Energy (OSTI)

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.

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

1995-02-01T23:59:59.000Z

106

Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis  

E-Print Network (OSTI)

Lithium Diisopropylamide-Mediated Ortholithiations: Lithium Chloride Catalysis Lekha Gupta, 2008 Ortholithiations of a range of arenes mediated by lithium diisopropylamide (LDA) in THF at -78 °C protocols with unpurified commercial samples of n-butyl- lithium to prepare LDA or commercially available

Collum, David B.

107

Coordination of dibensothiophenes and corannulenes to organometallic ruthenium (II) fragments  

DOE Green Energy (OSTI)

This dissertation contains five papers in the format required for journal publication which describe (in part) my research accomplishments as a graduate student at Iowa State University. This work can be broadly categorized as the binding of weakly-coordinating ligands to cationic organometallic ruthenium fragments, and consists of two main areas of study. Chapters 2-4 are investigations into factors that influence the binding of dibenzothiophenes to {l_brace}Cp'Ru(CO){sub 2}{r_brace}{sup +} fragments, where Cp' = {eta}{sup 5}-C{sub 5}H{sub 5} (Cp) and {eta}{sup 5}-C{sub 5}Me{sub 5} (Cp*). Chapters 5 and 6 present the synthesis and structural characterization of complexes containing corannulene buckybowls that are {eta}{sup 6}-coordinated to {l_brace}Cp*Ru{r_brace}{sup +} fragments. The first chapter contains a brief description of the difficulty in lowering sulfur levels in diesel fuel along with a review of corannulene derivatives and their metal complexes. After the final paper is a short summary of the work herein (Chapter 7). Each chapter is independent, and all equations, schemes, figures, tables, references, and appendices in this dissertation pertain only to the chapter in which they appear.

Vecchi, Paul Anthony

2005-05-01T23:59:59.000Z

108

Molecular-Level Design of Heterogeneous Chiral Catalysis  

SciTech Connect

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.

Francisco Zaera

2012-03-21T23:59:59.000Z

109

Argonne Chemical Sciences & Engineering - People - Catalysis and Energy  

NLE Websites -- All DOE Office Websites (Extended Search)

Management and Support Management and Support Heterogeneous Catalysis Homogeneous Catalysis Fuel Cell Engineering Hydrogen and Fuel Cell Materials Ceramic Electrochemistry Electrochemical Projects Support Management and Support Theodore R. Krause, Chemical Engineer and Department Manager phone: 630/252-4356, fax: 630/972-4463, e-mail: krauset@anl.gov PhD, Chemical Engineering, University of Delaware Catalyst formulations and characterization Reaction kinetics Catalyst fundamentals Hydrogen production technologies Laurie A. Carbaugh, Administrative Secretary phone: 630/252-7556, fax: 630/252-9917, e-mail: laurie.carbaugh@anl.gov Romesh Kumar, Senior Chemical Engineer phone: 630/252-4342, fax: 630/252-4176, e-mail: kumar@anl.gov PhD, Chemical Engineering, University of California, Berkeley

110

Pacific Northwest National Laboratory Catalysis Highlights for FY2007  

DOE Green Energy (OSTI)

To reduce the nation’s dependence on imported oil, the U.S. Department of Energy (DOE) and other federal and private agencies are investing in understanding catalysis. This report focuses on catalysis research conducted by Pacific Northwest National Laboratory (PNNL) and its collaborators. Using sophisticated instruments in DOE’s Environmental Molecular Sciences Laboratory, a national scientific user facility, research was conducted to answer key questions related to the nation’s use of automotive fuels. Research teams investigated how hydrogen can be safely stored and efficiently released, critical questions to use this alternative fuel. Further, they are answering key questions to design molecular catalysts to control the transfer of hydrogen atoms, hydrides, and protons important to hydrogen production. In dealing with today’s fuels, researchers examined adsorption of noxious nitrous oxides in automotive exhaust. Beyond automotive fuel, researchers worked on catalysts to harness solar power. These catalysts include the rutile and anatase forms of titanium dioxide. Basic research was conducted on designing catalysts for these and other applications. Our scientists examined how to build catalysts with the desired properties atom by atom and molecule by molecule. In addition, this report contains brief descriptions of the outstanding accomplishments of catalysis experts at PNNL.

Garrett, Bruce C.

2007-11-15T23:59:59.000Z

111

Transport of Molecular Motor Dimers in Burnt-Bridge Models  

E-Print Network (OSTI)

Dynamics of molecular motor dimers, consisting of rigidly bound particles that move along two parallel lattices and interact with underlying molecular tracks, is investigated theoretically by analyzing discrete-state stochastic continuous-time burnt-bridge models. In these models the motion of molecular motors is viewed as a random walk along the lattices with periodically distributed weak links (bridges). When the particle crosses the weak link it can be destroyed with a probability $p$, driving the molecular motor motion in one direction. Dynamic properties and effective generated forces of dimer molecular motors are calculated exactly as a function of a concentration of bridges $c$ and burning probability $p$ and compared with properties of the monomer motors. It is found that the ratio of the velocities of the dimer and the monomer can never exceed 2, while the dispersions of the dimer and the monomer are not very different. The relative effective generated force of the dimer (as compared to the monomer) also cannot be larger than 2 for most sets of parameters. However, a very large force can be produced by the dimer in the special case of $c=1/2$ for non-zero shift between the lattices. Our calculations do not show the significant increase in the force generated by collagenase motor proteins in real biological systems as predicted by previous computational studies. The observed behavior of dimer molecular motors is discussed by considering in detail the particle dynamics near burnt bridges.

Alexander Yu. Morozov; Anatoly B. Kolomeisky

2007-09-21T23:59:59.000Z

112

Electrodeposited ruthenium oxide thin films for supercapacitor: Effect of surface treatments  

E-Print Network (OSTI)

Electrodeposited ruthenium oxide thin films for supercapacitor: Effect of surface treatments V Supercapacitor is similar to a regular capacitor in operation; however, it offers a very high capacitance for supercapacitor should be able to get oxidized and reduce reversibility between various oxidation states [1

Chow, Lee

113

Studies on activated carbon capacitor materials loaded with different amounts of ruthenium oxide  

E-Print Network (OSTI)

speci®c capacitance [4]. However, the cost of ruthenium and its compounds limits its wide spread usage in electric/hybrid vehicles and consumer electronics. Substitutes for Ru oxides do not show compar- able 100 F/g, much lower than 720 F/g reported for amorphous RuO2. Wilde et al. [9] synthesized SrRuO3

Popov, Branko N.

114

TEMPERATURE-PROGRAMMED DESORPTION AND REACTION OF CO AND H2 ON ALUMINA-SUPPORTED RUTHENIUM CATALYST  

E-Print Network (OSTI)

over Group VIII Metal Catalysts" J.T. Kummer and P.H.and Fischer- Iron Catalyst", to be published. P.R. Wentrek,on Alumina-supported Ruthenium Catalyst" to be published. M.

Low, Gordon Gongngai

2011-01-01T23:59:59.000Z

115

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

Science Conference Proceedings (OSTI)

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.

Sobolevskiy, Anatoly (Orlando, FL); Rossin, Joseph A. (Columbus, OH); Knapke, Michael J. (Columbus, OH)

2011-07-12T23:59:59.000Z

116

Hydrogen catalysis and scavenging action of Pd-POSS nanoparticles  

DOE Green Energy (OSTI)

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.

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

2007-02-01T23:59:59.000Z

117

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Ceramic Electrochemistry Ceramic Electrochemistry * Members * Contact * Publications * Overview * Solid Oxide Fuel Cells * Steam Electrolysis Catalysis & Energy Conversion Home Ceramic Electrochemistry Dave Carter and solid oxide fuel cell Materials scientist John David Carter prepares a solid oxide electrochemical cell for high temperature testing. Research activities in the Ceramic Electrochemistry Group are focused on the development of ceramic-based electrochemical devices and components, such as Solid Oxide Fuel Cells (SOFC) and High Temperature Steam Electrolyzers (HTSE). This extends to materials synthesis, fabrication, and characterization. Solid Oxide Fuel Cell Research As part of the Solid State Energy Conversion Alliance (SECA) Core Technology Program, the goal of this research is the development of solid

118

Fuels and energy for the future: The role of catalysis  

SciTech Connect

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.

Rostrup-Nielsen, J.R.; Nielsen, R. [Haldor Topsoe Research Labs., Lyngby (Denmark)

2004-07-01T23:59:59.000Z

119

Inorganic Chemistry in Hydrogen Storage and Biomass Catalysis  

DOE Green Energy (OSTI)

Making or breaking C-H, B-H, C-C bonds has been at the core of catalysis for many years. Making or breaking these bonds to store or recover energy presents us with fresh challenges, including how to catalyze these transformations in molecular systems that are 'tuned' to minimize energy loss and in molecular and material systems present in biomass. This talk will discuss some challenging transformations in chemical hydrogen storage, and some aspects of the inorganic chemistry we are studying in the development of catalysts for biomass utilization.

Thorn, David [Los Alamos National Laboratory

2012-06-13T23:59:59.000Z

120

Materials Design and Discovery: Catalysis and Electrical Energy Storage  

NLE Websites -- All DOE Office Websites (Extended Search)

and Discovery: Catalysis and Discovery: Catalysis and Electrical Energy Storage Presenter: N ichols A . R omero, A LCF ESP p ost---doc: Anouar B enali, A LCF PI: L arry C urAss, A NL M SD a nd C NM Comments from a reviewer on "Material Design and Discovery" from a proposal § How c ould t his m achine w ith t hese p rograms b e u sed t o d esign a n ew s olar c ell? Or a n ew c ure f or A IDS? O r a n ew h igh---T s uperconductor? T his i s n ot i ntended a s a trivial q uesAon. T he p resent m ethod o f D ISCOVERY r elies o n t he t rained h uman mind ( insight) a nd e xperiment ( serendipity). C omputaAonal s cience s o f ar h as n ot delivered a ny n ew d iscoveries b ecause i t l acks t he p ossibility o f s erendipity. T he greatest s uccess o f c omputaAonal c hemistry h as b een i mproved i nsight i nto t he way m aterial b ehaves

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

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

DOE Patents (OSTI)

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.

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

1980-11-03T23:59:59.000Z

122

Interaction and reactivity of nitric oxide and carbon monoxide on ruthenium surfaces  

DOE Green Energy (OSTI)

A multifaceted investigation of the reduction of nitric oxide by carbon monoxide using a ruthenium (102) single crystal catalyst in the pressure range 10/sup -3/ to 10 Torr and temperature range of 300 to 475/sup 0/C has been undertaken. Kinetic and isotopic results indicate that the reaction products CO/sub 2/ and N/sub 2/ were produced via two reaction mechanisms. Using a reducing gas mixture (low P/sub NO//P/sub CO/ ratio) a two site mechanism was operative involving NO dissociation. The carbon monoxide kinetic order varied from +1 to -3 and the nitric oxide order varied from +1 to 0. The catalyst under these conditions was determined to be metallic ruthenium with oxygen bonded within the first surface layer. The oxygen was unreactive and formed a (1 x 3)-0 LEED pattern. Under oxidizing conditions (high P/sub NO//P/sub CO/ ratio) the catalyst was ruthenium dioxide and the functional mechanism under these reaction conditions yielded a nitric oxide order of +2 to -4. Inclusion of a site poisoning mechanism under reducing conditions and an RuO/sub 2/ growth mechanism involving ruthenium cation transfer under oxidizing conditions into the kinetic rate laws led to an overall rate law which could be fit to the carbon monoxide and nitric oxide order plots. Using isotopically oxygen labelled reactants, it was observed that the three possible isotopes of carbon dioxide were produced. A ..gamma..-CO surface species is postulated as an intermediate in the exchange process. The reaction was observed to be initially surface structure insensitive and the reaction kinetics were derived using a Langmuir-Hinshelwood formalism.

Quick, E.E.

1980-03-01T23:59:59.000Z

123

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Atom-Efficient Chemical Transformations Atom-Efficient Chemical Transformations iact logo Argonne National Laboratory along with its academic partners has established an Energy Frontier Research Center, the Institute for Atom-efficient Chemical Transformations (IACT) whose focus is to advance the science of catalysis for the efficient conversion of energy resources into usable forms. IACT is one of 46 Energy Frontier Research Centers that DOE has established in the United States. IACT is a partnership among world-class scientists at Argonne National Laboratory, Northwestern University, Purdue University, University of Wisconsin-Madison, and Brookhaven National Laboratory. Using a multidisciplinary approach involving integrated catalyst synthesis, advanced characterization, catalytic experimentation, and computation, IACT is addressing key

124

Tandem Catalysis in Nanocrystal Interfaces | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Interfaces Interfaces Tandem Catalysis in Nanocrystal Interfaces July 18, 2011 - 2:45pm View(active tab) Edit Workflow Addthis A unique new bilayer nanocatalyst system. | Image courtesy of Yang group A unique new bilayer nanocatalyst system. | Image courtesy of Yang group What does this mean for me? A prime example of these applications is artificial photosynthesis -- the effort to capture energy from the sun and transform it into electricity or chemical fuels. Catalysts (substances that speed up the rates of chemical reactions without themselves being chemically changed) are used to initiate virtually every industrial manufacturing process that involves chemistry. With the advent of nano-sized catalysts, metal and metal oxide catalysts have surged in importance. Recently, researchers at the Department's Lawrence Berkeley National

125

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen and Fuel Cell Materials Hydrogen and Fuel Cell Materials * Members * Contact * Publications * Overview * Alternative Electrocatalysts * Electrocatalyst Durability * Hydrogen Storage * Electrocatalyst Degradation Catalysis & Energy Conversion Home Hydrogen and Fuel Cell Materials Polymer electrolyte fuel cell (PEFC) systems are promising alternatives to conventional power systems for transportation, portable, and stationary applications due to their high efficiency of converting fuel to electricity, low emissions, and low operating temperatures. Three major issues for PEFC systems, especially for portable and transportation use, are cost, lifetime, and fuel storage, with the fuel of choice being hydrogen. Argonne's Hydrogen and Fuel Cell Materials group has active research projects in these three areas, to enable the use of this promising technology in a variety of applications.

126

Key Accomplishments @ Catalysis: Reactivity and Structure Group | Chemistry  

NLE Websites -- All DOE Office Websites (Extended Search)

Recent Key Accomplishments Recent Key Accomplishments WGS: Importance of the Metal-Oxide Interface in Catalysis: In Situ Studies of the Water-Gas Shift Reaction by Ambient-Pressure X-ray Photoelectron Spectroscopy A New Type of Strong Metal-Support Interaction and the Production of H-2 through the Transformation of Water on Pt/CeO2(111) and Pt/CeOx/TiO2(110) Catalysts In situ studies of CeO2-supported Pt, Ru, and Pt-Ru alloy catalysts for the water-gas shift reaction: Active phases and reaction intermediates In situ/operando studies for the production of hydrogen through the water-gas shift on metal oxide catalysts Mechanistic understanding of WGS catalysts from first principles: Au(111) Supported Oxide Nanoparticles Theoretical catalyst optimization of WGS catalysts: Cu(111) supported oxide nanostructures

127

Molecular surface science of heterogeneous catalysis. History and perspective  

DOE Green Energy (OSTI)

A personal account is given of how the author became involved with modern surface science and how it was employed for studies of the chemistry of surfaces and heterogeneous catalysis. New techniques were developed for studying the properties of the surface monolayers: Auger electron spectroscopy, LEED, XPS, molecular beam surface scattering, etc. An apparatus was developed and used to study hydrocarbon conversion reactions on Pt, CO hydrogenation on Rh and Fe, and NH/sub 3/ synthesis on Fe. A model has been developed for the working Pt reforming catalyst. The three molecular ingredients that control catalytic properties are atomic surface structure, an active carbonaceous deposit, and the proper oxidation state of surface atoms. 40 references, 21 figures. (DLC)

Somorjai, G.A.

1983-08-01T23:59:59.000Z

128

Molecular computations for reactions and phase transitions: applications to protein stabilization, hydrates and catalysis  

E-Print Network (OSTI)

In this work we have made significant contributions in three different areas of interest: therapeutic protein stabilization, thermodynamics of natural gas clathrate-hydrates, and zeolite catalysis. In all three fields, ...

Anderson, Brian J.

129

Transformation of Sorbitol to Biofuels by Heterogeneous Catalysis: Chemical and Industrial  

E-Print Network (OSTI)

Transformation of Sorbitol to Biofuels by Heterogeneous Catalysis: Chemical and Industrial ainsi que des exemples d'applications industrielles. Abstract -- Transformation of Sorbitol to Biofuels and biodiesel production led to first generation biofuels. Nowadays, research is focused on lignocellulosic

Recanati, Catherine

130

Final Report on Kokes Awards for the 20th North American Catalysis Society Meeting  

SciTech Connect

This Final Report describes how the Kokes Awards program was carried out for the 2007 meeting with regard to selection of students and disbursement of funds received from DOE and other sources. The objective of the Richard J. Kokes Travel Award program of the American Catalysis Society is to encourage graduate students to attend and participate meaningfully in the biennial North American Catalysis Society Meeting.

Wong, Michael S.

2008-01-01T23:59:59.000Z

131

Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal  

NLE Websites -- All DOE Office Websites (Extended Search)

Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Catalyst in MEAs Title Bridge to Fuel Cell Molecular Catalysis: 3D Non-Platinum Group Metal Catalyst in MEAs Publication Type Journal Article Year of Publication 2012 Authors Zhu, Xiaobing, John B. Kerr, Qinggang He, Gi Suk Hwang, Zulima Martin, Kyle Clark, Adam Z. Weber, and Nana Zhao Journal ECS Transactions Volume 45 Issue 2 Pagination 143 - 152 Date Published 04/2012 ISSN 1938-6737 Abstract Transition metal porphyrin complexes have been mounted in a three dimensional homogenous distribution inside the ionomer of catalyst layers in MEAs to achieve competitive fuel cell catalysis activity. The effect of electrode components including ionomer, carbon, catalyst, and mediator, and ionomer film thickness, is investigated in fuel cell molecular catalysis system. Membrane electrode assembly (MEA) durability testing has been conducted. SEM and TEM techniques are employed to investigate molecular catalysis electrode micro- and nano- structure and morphology. To date, surprisingly, the best fuel cell performance, i.e. 1280 mA/cm2 of maximum/short-circuit current density is achieved, approaching that of Pt-based electrode, indicating higher turnover frequencies than Pt although with poorer voltages.

132

NOX REDUCTION FOR LEAN EXHAUST USING PLASMA ASSISTED CATALYSIS  

DOE Green Energy (OSTI)

Currently CARB estimates on road diesel vehicles contribute 50% of the NOX and 78% of the particulates being discharged from mobile sources. Diesel emissions obviously must be reduced if future air quality targets are to be met. A critical technological barrier exists because there are no commercial technologies available, which can reduce NOX from diesel (lean), exhaust containing 5-15% O2 concentration. One promising approach to reducing NOX and particulates from diesel exhaust is to use a combination of plasma with catalyst. Plasma can be generated thermally or non-thermally. Thermal plasma is formed by heating the system to an exceedingly high temperature (>2000 C). High temperature requirements for plasma makes thermal plasma inefficient and requires skillful thermal management and hence is considered impractical for mobile applications. Non-thermal plasma directs electrical energy into the creation of free electrons, which in turn react with gaseous species thus creating plasma. A combination of non-thermal plasma with catalysts can be referred to Plasma Assisted Catalysts or PAC. PAC technology has been demonstrated in stationary sources where non-thermal plasma catalysis is carried out in presence of NH3 as a reductant. In stationary applications NO is oxidized to HNO3 and then into ammonium nitrate where it is condensed and removed. This approach is impractical for mobile application because of the ammonia requirement and the ultimate mechanism by which NOX is removed. However, if a suitable catalyst can be found which can use onboard fuel as reductant then the technology holds a considerable promise. NOX REDUCTION FOR LEAN EXHAUST USING PLASMA ASSISTED CATALYSIS Ralph Slone, B. Bhatt and Victor Puchkarev NOXTECH INC. In addition to the development of an effective catalyst, a non-thermal plasma reactor needs be scaled and demonstrated along with a reliable and cost effective plasma power source and onboard HC source needs to be proven. Under the work sponsored by DOE and SCAQMD Noxtech is developing a cost effective and reliable PAC system for mobile applications. The goal of the program is to develop a suitable catalyst with the ability to remove high levels of NOx at reasonable space velocities. This new catalyst will then be used to scale the technology to treat exhaust from 80Hp engine and eventually to demonstrate the technology on 200 and 400 Hp engine applications. Using the 2004 EPA proposed regulation as a standard, it is clear in order for PAC system to be commercially viable it needs to remove NOX by 70% or better. It is further assumed from past experience that 30,000 HR-1 space velocities are necessary to ensure a good compact design.

Bhatt, B.

2000-08-20T23:59:59.000Z

133

Argonne Chemical Sciences & Engineering - Publications - Catalysis and  

NLE Websites -- All DOE Office Websites (Extended Search)

Fuel Cell Engineering Fuel Cell Engineering A H. Adachi, S. Ahmed, S. H. D. Lee, D. Papadias, R. K. Ahluwalia, J. C. Bendert, S. A. Kanner, and Y. Yamazaki, "A Natural-Gas Fuel Processor for a Residential Fuel Cell System," Journal of Power Sources, accepted for publication (2009) S. Ahmed, "Renewable Power Sources," (invited talk), University of Houston, Houston, TX, March 22-23, 2012. S. Ahmed, "Fuel Cell Based Combined Heat and Power for Small Systems (1-100 kW)," (invited talk), University of Houston, Houston, TX, March 22-23, 2012. S. Ahmed, R. Ahluwalia, S. H. D. Lee and S. Lottes, "A Gasoline Fuel Processor Designed to Study Quick-Start Performance," Journal of Power Sources 154(1), 214-222 (2006) C S. Y. Choung, M. Ferrandon, and T. Krause, "Pt-Re Bimetallic Supported on CeO2-ZrO2 Mixed Oxides as Water-Gas Shift Catalysts," Catalysis Today 99, 257-262 (2005)

134

Lean NOx catalysis for gasoline fueled European cars  

SciTech Connect

There is increasing interest in operating gasoline fueled passenger cars lean of the stoichiometric air/fuel (A/F) ratio to improve fuel economy. These types of engines will operate at lean A/F ratios while cruising at partial load, and return to stoichiometric or even rich conditions when more power is required. The challenge for the engine and catalyst manufacturer is to develop a system which will combine the high activity rates of a state-of-the-art three-way catalyst (TWC) with the ability to reduce nitrogen oxides (NOx) in the presence of excess oxygen. The objective is to achieve the future legislative limits (EURO III/IV) in the European Union. Recent developments in automotive pollution control catalysis show that the use of NOx adsorption materials is a suitable way to reduce NOx emissions of gasoline-fueled lean-burn engines. However, the primary task for the implementation of this technology in the European market will be to improve the catalyst`s high-temperature stability and to decrease its susceptibility to sulfur poisoning. Outlined here are results of a recent R and D program to achieve NOx reduction under lean-burn gasoline engine conditions. Model gas test results as well as engine bench data are used for discussion of the parameters which control NOx adsorption efficiency under various conditions.

NONE

1997-02-01T23:59:59.000Z

135

Design of Catalytic Materials for Plasma Assisted Catalysis System  

DOE Green Energy (OSTI)

In recent years, the Plasma Assisted Catalysis (PAC) approach for controlling NOx and/or particulate emissions from mobile diesel engines has received a significant amount of attention from researchers. Substantial work has been performed by various researchers to develop an understanding of the reaction mechanisms in a plasma reactor in conjunction with conventional lean-NOx catalyst materials. However, less effort has been devoted to systematically investigating new catalyst materials specifically designed for application in the PAC system. Since it is believed that plasma produces a unique environment for a catalyst bed (i.e. oxidation of NO to NO2 and partial oxidation/reforming of hydrocarbon reductants in the exhaust), new catalytic materials that take advantage of the plasma reactor conditions need to be studied. Optimum catalyst materials will be required in order to develop a PAC system that achieves maximum deNOx performance over the wide range of operating conditions in which the system will be required to operate for application on heavy duty diesel engines. This presentation discusses the issues involved in designing catalytic materials for achieving high NOx conversion in a laboratory test PAC system, and what is required to improve the catalyst materials further for application in an on-engine environment.

Park, Paul W.

2000-08-20T23:59:59.000Z

136

Dimerization-assisted energy transport in light-harvesting complexes  

E-Print Network (OSTI)

We study the role of the dimer structure of light-harvesting complex II (LH2) in excitation transfer from the LH2 (without a reaction center (RC)) to the LH1 (surrounding the RC), or from the LH2 to another LH2. The excited and un-excited states of a bacteriochlorophyll (BChl) are modeled by quasi-spin. In the framework of quantum open system theory, we represent the excitation transfer as the total leakage of the LH2 system, and then calculate the transfer efficiency and average transfer time at a low enough temperature. For different initial states with various quantum superposition properties, we study how the dimerization of the B850 BChl ring can enhance the transfer efficiency and shorten the average transfer time.

Yang, S; Song, Z; Sun, C P

2010-01-01T23:59:59.000Z

137

Dimerization-assisted energy transport in light-harvesting complexes  

E-Print Network (OSTI)

We study the role of the dimer structure of light-harvesting complex II (LH2) in excitation transfer from the LH2 (without a reaction center (RC)) to the LH1 (surrounding the RC), or from the LH2 to another LH2. The excited and un-excited states of a bacteriochlorophyll (BChl) are modeled by a quasi-spin. In the framework of quantum open system theory, we represent the excitation transfer as the total leakage of the LH2 system and then calculate the transfer efficiency and average transfer time. For different initial states with various quantum superposition properties, we study how the dimerization of the B850 BChl ring can enhance the transfer efficiency and shorten the average transfer time.

S. Yang; D. Z. Xu; Z. Song; C. P. Sun

2010-02-02T23:59:59.000Z

138

Benchmark calculations for elastic fermion-dimer scattering  

E-Print Network (OSTI)

We present continuum and lattice calculations for elastic scattering between a fermion and a bound dimer in the shallow binding limit. For the continuum calculation we use the Skorniakov-Ter-Martirosian (STM) integral equation to determine the scattering length and effective range parameter to high precision. For the lattice calculation we use the finite-volume method of L\\"uscher. We take into account topological finite-volume corrections to the dimer binding energy which depend on the momentum of the dimer. After subtracting these effects, we find from the lattice calculation kappa a_fd = 1.174(9) and kappa r_fd = -0.029(13). These results agree well with the continuum values kappa a_fd = 1.17907(1) and kappa r_fd = -0.0383(3) obtained from the STM equation. We discuss applications to cold atomic Fermi gases, deuteron-neutron scattering in the spin-quartet channel, and lattice calculations of scattering for nuclei and hadronic molecules at finite volume.

Shahin Bour; H. -W. Hammer; Dean Lee; Ulf-G. Meißner

2012-06-08T23:59:59.000Z

139

Methane activation on ruthenium: the nature of the surface intermediates T.V. Choudhary and D.W. Goodman*  

E-Print Network (OSTI)

) by steam reforming [1,2], partial oxidation [3,4], autothermal reforming [2,5] or CO2 reforming [6,20]. In a similar fashion, we have investigated step- wise methane reforming (methane decomposition in step IMethane activation on ruthenium: the nature of the surface intermediates T.V. Choudhary and D

Goodman, Wayne

140

Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications  

Science Conference Proceedings (OSTI)

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 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

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

2007-09-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Lean NOx Trap Catalysis for Lean Natural Gas Engine Applications  

DOE Green Energy (OSTI)

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

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

2007-09-01T23:59:59.000Z

142

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

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

1.2011]: Energy Efficiency, Catalysis and Open Source 1.2011]: 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 to more efficient, safer and cleaner chemical reactions that work at lower pressures and temperatures and create less waste. In one project, Dr. Woo is working to understand the chemistry behind fast pyrolysis for creating bio-oil from biomass. Fast pyrolysis quickly heats up biomass (such as corn stalks and leaves) in the absence of oxygen to

143

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

Science Conference Proceedings (OSTI)

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.

Abhaya Datye

2010-07-02T23:59:59.000Z

144

Phase selectively soluble polymer supports to facilitate homogeneous catalysis  

E-Print Network (OSTI)

Soluble polymers that have phase selective solubility are useful in synthesis because they simplify purification and separation. Such selectively soluble polymers simplify catalyst, reagent, and product recovery and enable the use of Green chemistry principles in homogeneous catalysis. However, while homopolymers have been reported that have excellent thermal and phase-dependent solubility, less is known about copolymers. Also, less is known about the phase selective solubility of polar aprotic N,N-dialkyl polyacrylamides. This work describes a library synthesis of dye-labeled poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers and study of the effects of polymer composition in phase selective solubility of these copolymers. To study the relative importance of n-octadecyl versus n-butyl groups, copolymers with different ratios of n-octadecylacrylamide and n-butylacrylamide but with similar degrees of polymerization and polydispersity were prepared by a split-pool synthesis using a highly soluble poly(N-acryloxy-2-dodecylsuccinimide) as the precursor. Polymer sequestrants were used to remove excess amines and the byproduct N-hydroxyl-2- dodecylsuccinimide without fractionation of the polyacrylamides. Results demonstrated that poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers’ phase selective solubility is equally dependant of the polar n-butyl and nonpolar n-octadecyl groups on the copolymers. Dye-labeled poly(N,N-dialkylacrylamide)s prepared by the polymerization of N,N-dialkylacrylamides monomers with methyl, ethyl, propyl, butyl, hexyl, and dodecyl N-alkyl groups in a variety of thermomorphic or latent biphasic polar/nonpolar solvent mixtures were also prepared. Studies showed that poly(N,N-dialkylacrylamide)s have phase selective solubility that is highly dependent of the size of the N-alkyl group. Soluble polymers are known to be useful supports for catalysts. This thesis also describes approaches to immobilization of a variety of catalysts on polyisobutylene (PIB). The most effective of these catalysts were analogs of pyridyl N-oxides that have been used as organocatalysts for the catalytic allylation of a variety of aromatic aldehydes. PIB-supported N-oxide promoted the allylation of aldehydes in up to 99% isolated yield. The products were isolated in the polar phase of a thermomorphic system and the catalyst was recycled through five cycles.

Ortiz-Acosta, Denisse

2007-12-01T23:59:59.000Z

145

Bose-Hubbard dimer scattered from a potential barrier: from co-tunneling to dissociation  

E-Print Network (OSTI)

We consider a Bose-Hubbard dimer scattered from a potential barrier. A numerical approach has been developed to treat the stationary scattering problem. It allows to compute the tunneling and dissociation probabilities for arbitrary shape of the potential barrier and arbitrary kinetic energy of the dimer. The obtained results are shown to be in agreement with previous studies of the dimer wave-packet dynamics [A.R.Kolovsky, J.Link, and S.Wimberger, New J. of Phys. {\\bf 14}, 075002 (2012)]. In particular, we reproduce the effect of resonant tunneling found in the cited paper and show that this effect can be enhanced by decreasing the dimer kinetic energy.

Dmitrii N. Maksimov; Andrey R. Kolovsky

2013-11-12T23:59:59.000Z

146

Oxygen and hydrogen evolution reaction on oriented single crystals of ruthenium dioxide  

DOE Green Energy (OSTI)

A novel design for water electrolysis using a solid polymer electrolyte is being developed by General Electric. Ruthenium is one of the best electrocatalysts for the oxygen evolution reaction. There are problems connected with the significant loss in electrocatalytic activity with time. This performance degradation is presumably due to the gradual formation of an RuO/sub 2/ film. We have performed electrochemical measurements on (100), (110) and (111) oriented single crystals of RuO/sub 2/ in order to elucidate the mechanism of the electrocatalytic process. Large single crystals were grown by the vapor transport method. Our investigation has revealed several interesting differences for the various orientations. This study indicates that RuO/sub 3/ may be an important intermediate species prior to oxygen evolution and that the formation of the RuO/sub 3/ is the rate limiting process. Similar results were previously obtained for IrO/sub 2/.

Berger, L I; Pollak, F H; Canivez, Y; O'Grady, W

1979-01-01T23:59:59.000Z

147

Simulated X-Ray Absorption Spectroscopy on the Water Dimer  

DOE Green Energy (OSTI)

The ability of an individual H{sub 2}O molecule to form multiple hydrogen bonds with neighboring molecules makes it an ideal substance for the study of hydrogen bonding. X-ray absorption spectroscopy (XAS) can be used to study what intermolecular structures the hydrogen-bonded water molecules form. XAS excites core electrons from the oxygen 1 s atomic orbital to an unoccupied orbital. The resulting absorption spectrum shows the energy levels of the unoccupied orbitals, which in turn is dependent on the intermolecular structure of the H{sub 2}O system. Previous studies using molecular dynamics computer simulations have concluded that the intermolecular structure of liquid water is a distorted tetrahedron. Yet x-ray absorption spectra show discrepancies between liquid water and ice Ih, which is already known to have a rigid tetrahedral structure. The research group, which is based in the University of Sweden in Stockholm and the Stanford Synchrotron Radiation Laboratory at the Stanford Linear Accelerator Center, has studied the possible presence of broken hydrogen bonds in the liquid water intermolecular structure to explain these deviations. Computer simulations are used to construct theoretical absorption spectra for models of liquid water including broken hydrogen bonds. Creating such models requires controlling variables. The simplest method of isolating individual variables, such as hydrogen bond length and angles, is to study the water dimer. Here, the water dimer is used to study how the absorption spectra change with the way the water molecules are positioned and oriented relative to each other.

Wung, A

2004-02-05T23:59:59.000Z

148

Dimerization of a Viral SET Protein Endows its Function  

SciTech Connect

Histone modifications are regarded as the most indispensible phenomena in epigenetics. Of these modifications, lysine methylation is of the greatest complexity and importance as site- and state-specific lysine methylation exerts a plethora of effects on chromatin structure and gene transcription. Notably, paramecium bursaria chlorella viruses encode a conserved SET domain methyltransferase, termed vSET, that functions to suppress host transcription by methylating histone H3 at lysine 27 (H3K27), a mark for eukaryotic gene silencing. Unlike mammalian lysine methyltransferases (KMTs), vSET functions only as a dimer, but the underlying mechanism has remained elusive. In this study, we demonstrate that dimeric vSET operates with negative cooperativity between the two active sites and engages in H3K27 methylation one site at a time. New atomic structures of vSET in the free form and a ternary complex with S-adenosyl homocysteine and a histone H3 peptide and biochemical analyses reveal the molecular origin for the negative cooperativity and explain the substrate specificity of H3K27 methyltransferases. Our study suggests a 'walking' mechanism, by which vSET acts all by itself to globally methylate host H3K27, which is accomplished by the mammalian EZH2 KMT only in the context of the Polycomb repressive complex.

H Wei; M Zhou

2011-12-31T23:59:59.000Z

149

Applied Catalysis B: Environmental 37 (2002) 2735 NOx reduction by urea under lean conditions over  

E-Print Network (OSTI)

Applied Catalysis B: Environmental 37 (2002) 27­35 NOx reduction by urea under lean conditions over using a single step sol­gel process (designated as 2% Pt-SG) and tested its activity for NOx reduction and hydrothermally stable in the range of 150­500 C in the reduction of NOx by hy- drocarbons or oxygenated

Gulari, Erdogan

150

FORCE-CLAMP SPECTROSCOPY DETECTS RESIDUE CO-EVOLUTION IN ENZYME CATALYSIS  

E-Print Network (OSTI)

distant correlated mutations in E. coli thioredoxin. Our findings show that evolutionary anti- correlated of distant residue co-evolution in enzyme catalysis. The acquisition of adequate activity by an enzyme,10). Analysis of co-evolving residues has been used to explore functional coupling in processes like protein

Fernandez, Julio M.

151

Catalysis looks to the future. Panel on new directions in catalytic science and technology  

Science Conference Proceedings (OSTI)

Catalysts play a vital role in providing society with fuels, commodity and fine chemicals, pharmaceuticals, and means for protecting the environment. To be useful, a good catalyst must have a high turnover frequency (activity), produce the right kind of product (selectivity), and have a long life (durability), all at an acceptable cost. Research in the field of catalysis provides the tools and understanding required to facilitate and accelerate the development of improved catalysts and to open opportunities for the discovery of new catalytic processes. The aim of this report is to identify the research opportunities and challenges for catalysis in the coming decades and to detail the resources necessary to ensure steady progress. Chapter 2 discusses opportunities for developing new catalysts to meet the demands of the chemical and fuel industries, and the increasing role of catalysis in environmental protection. The intellectual challenges for advancing the frontiers of catalytic science are outlined in Chapter 3. The human and institutional resources available in the US for carrying out research on catalysis are summarized in Chapter 4. The findings and recommendations of the panel for industry, academe, the national laboratories, and the federal government are presented in Chapter 5.

Not Available

1992-12-31T23:59:59.000Z

152

ISHHC XIII International Symposium on the Relations betweenHomogeneous and Heterogeneous Catalysis  

SciTech Connect

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.

Somorjai (Ed.), G.A.

2007-06-11T23:59:59.000Z

153

Characterization of a dissolved oxygen sensor made of plastic optical fiber coated with ruthenium-incorporated solgel  

SciTech Connect

A dissolved oxygen sensor made of plastic optical fiber as the substrate and dichlorotris (1, 10-phenanthroline) ruthenium as a fluorescence indicator is studied. Oxygen quenching characteristics of both intensity and phase were measured; the obtained characteristics showed deviation from the linear relation described by the Stern-Volmer equation. A two-layer model is proposed to explain the deviation, and main parameters can be deduced with the model.

Chu Fenghong; Yang Junjie; Cai Haiwen; Qu Ronghui; Fang Zujie

2009-01-10T23:59:59.000Z

154

Isotope effects and Born-Oppenheimer breakdown in excited singlet states of the lithium dimer  

E-Print Network (OSTI)

Isotope effects and Born-Oppenheimer breakdown in excited singlet states of the lithium dimer A-Oppenheimer breakdown in four singlet electronic states correlating with (2s 2s), (2s 2p), and (2p 2p) lithium atoms , and 1 1 g states of the lithium dimer. This paper also reports Fourier transform measurements of the B

Le Roy, Robert J.

155

The roles of redox active cofactors in catalysis : structural studies of iron sulfur cluster and flavin dependent enzymes  

E-Print Network (OSTI)

Cofactors are highly prevalent in biological systems and have evolved to take on many functions in enzyme catalysis. Two cofactors, flavin adenine dinucleotide (FAD) and [4Fe-4S] clusters, were originally determined to aid ...

Goldman, Peter John

2013-01-01T23:59:59.000Z

156

Charge Transfer and Support Effects in Heterogeneous Catalysis  

SciTech Connect

The kinetic, electronic and spectroscopic properties of two?dimensional oxide?supported catalysts were investigated in order to understand the role of charge transfer in catalysis. Pt/TiO{sub 2} nanodiodes were fabricated and used as catalysts for hydrogen oxidation. During the reaction, the current through the diode, as well as its I?V curve, were monitored, while gas chromatography was used to measure the reaction rate. The current and the turnover rate were found to have the same temperature dependence, indicating that hydrogen oxidation leads to the non?adiabatic excitation of electrons in Pt. A fraction of these electrons have enough energy to ballistically transport through Pt and overcome the Schottky barrier at the interface with TiO{sub 2}. The yield for this phenomenon is on the order of 10{sup ?4} electrons per product molecule formed, similar to what has been observed for CO oxidation and for the adsorption of many different molecules. The same Pt/TiO{sub 2} system was used to compare currents in hydrogen oxidation and deuterium oxidation. The current through the diode under deuterium oxidation was found to be greater than under hydrogen oxidation by a factor of three. Weighted by the difference in turnover frequencies for the two isotopes, this would imply a chemicurrent yield 5 times greater for D{sub 2} compared to H{sub 2}, contrary to what is expected given the higher mass of D{sub 2}. Reversible changes in the rectification factor of the diode are observed when switching between D{sub 2} and H{sub 2}. These changes are a likely cause for the differences in current between the two isotopes. In the nanodiode experiments, surface chemistry leads to charge flow, suggesting the possibility of creating charge flow to tune surface chemistry. This was done first by exposing a Pt/Si diode to visible light while using it as a catalyst for H{sub 2} oxidation. Absorption of the light in the Si, combined with the band bending at the interface, gives rise to a steady?state flow of hot holes to the surface. This leads to a decrease in turnover on the surface, an effect which is enhanced when a reverse bias is applied to the diode. Similar experiments were carried out for CO oxidation. On Pt/Si diodes, the reaction rate was found to increase when a forward bias was applied. When the diode was exposed to visible light and a reverse bias was applied, the rate was instead decreased. This implies that a flow of negative charges to the surface increases turnover, while positive charges decrease it. Charge flow in an oxide supported metal catalyst can be modified even without designing the catalyst as a solid state electronic device. This was done by doping stoichiometric and nonstoichiometric TiO{sub 2} films with F, and using the resulting oxides as supports for Pt films. In the case of stoichiometric TiO{sub 2}, F was found to act as an n?type dopant, creating a population of filled electronic states just below the conduction band, and dramatically increasing the conductivity of the oxide film. The electrons in those states can transfer to surface O, activating it for reaction with CO, and leading to increased turnover for CO oxidation. This reinforces the hypothesis that CO oxidation is activated by a flow of negative charges to the surface. The same set of catalysts was used for methanol oxidation. The electronic properties of the TiO{sub 2} films again correlated with the turnover rates, but also with selectivity. With stoichiometric TiO{sub 2} as the support, F?doping caused an increase in selectivity toward the formation of partial oxidation products, formaldehyde and methyl formate, versus the total oxidation product, CO{sub 2}. With non?stoichiometric TiO{sub 2}, F?doping had the reverse effect. Ambient Pressure X?Ray Photoelectron Spectroscopy was used to investigate this F?doping effect in reaction conditions. In O2 alone, and in CO oxidation conditions, the O1s spectrum showed a high binding energy peak that correlated in intensity with the activity of the different films: for stoichiomet

Hervier, Antoine

2011-12-21T23:59:59.000Z

157

Rhodium mediated bond activation: from synthesis to catalysis  

SciTech Connect

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 Brønsted 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.

Ho, Hung-An

2012-03-06T23:59:59.000Z

158

Geometric Restraint Drives On- and Off-pathway Catalysis by the Escherichia coli Menaquinol:Fumarate Reductase  

SciTech Connect

Complex II superfamily members catalyze the kinetically difficult interconversion of succinate and fumarate. Due to the relative simplicity of complex II substrates and their similarity to other biologically abundant small molecules, substrate specificity presents a challenge in this system. In order to identify determinants for on-pathway catalysis, off-pathway catalysis, and enzyme inhibition, crystal structures of Escherichia coli menaquinol:fumarate reductase (QFR), a complex II superfamily member, were determined bound to the substrate, fumarate, and the inhibitors oxaloacetate, glutarate, and 3-nitropropionate. Optical difference spectroscopy and computational modeling support a model where QFR twists the dicarboxylate, activating it for catalysis. Orientation of the C2-C3 double bond of activated fumarate parallel to the C(4a)-N5 bond of FAD allows orbital overlap between the substrate and the cofactor, priming the substrate for nucleophilic attack. Off-pathway catalysis, such as the conversion of malate to oxaloacetate or the activation of the toxin 3-nitropropionate may occur when inhibitors bind with a similarly activated bond in the same position. Conversely, inhibitors that do not orient an activatable bond in this manner, such as glutarate and citrate, are excluded from catalysis and act as inhibitors of substrate binding. These results support a model where electronic interactions via geometric constraint and orbital steering underlie catalysis by QFR.

Tomasiak, Thomas M.; Archuleta, Tara L.; Andréll, Juni; Luna-Chávez, César; Davis, Tyler A.; Sarwar, Maruf; Ham, Amy J.; McDonald, W. Hayes; Yankovskaya, Victoria; Stern, Harry A.; Johnston, Jeffrey N.; Maklashina, Elena; Cecchini, Gary; Iverson, Tina M. (Rochester-Med); (VA); (Vanderbilt); (MRCLMB); (UCSF)

2012-01-05T23:59:59.000Z

159

Conformational Diversity and Sub-states in Enzyme Catalysis | ornl.gov  

NLE Websites -- All DOE Office Websites (Extended Search)

Conformational Diversity and Sub-states in Enzyme Catalysis Conformational Diversity and Sub-states in Enzyme Catalysis November 01, 2013 Enzymes are great biocatalysts, and have attracted significant interest for industrial applications (including cellulosic ethanol) due to their remarkable catalytic efficiencies. The understanding of factors that enable enzymes to achieve the high catalytic efficiency will have large impact through design of new and powerful biocatalysts. Unfortunately, the understanding of these factors have largely remain a mystery so far. Using joint computational-experimental methodology we have developed a unique technique named quasi-anharmonic analysis (QAA) for identification of conformational diversity and conformational sub-states associated with enzyme function. As a result of this approach we have been able to develop

160

Major Successes of Theory-and-Experiment-Combined Studies in Surface Chemistry and Heterogeneous Catalysis.  

SciTech Connect

Experimental discoveries followed by theoretical interpretations that pave the way of further advances by experimentalists is a developing pattern in modern surface chemistry and catalysis. The revolution of modern surface science started with the development of surface-sensitive techniques such as LEED, XPS, AES, ISS and SIMS, in which the close collaboration between experimentalists and theorists led to the quantitative determination of surface structure and composition. The experimental discovery of the chemical activity of surface defects and the trends in the reactivity of transitional metals followed by the explanations from the theoretical studies led to the molecular level understanding of active sites in catalysis. The molecular level knowledge, in turn, provided a guide for experiments to search for new generation of catalysts. These and many other examples of successes in experiment-and-theory-combined studies demonstrate the importance of the collaboration between experimentalists and theorists in the development of modern surface science.

Somorjai, Gabor A.; Li, Yimin

2009-11-21T23:59:59.000Z

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161

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

DOE Green Energy (OSTI)

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.

Fabio H. Ribeiro

2011-06-05T23:59:59.000Z

162

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

SciTech Connect

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.

Fabio H. Ribeiro

2011-06-05T23:59:59.000Z

163

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

DOE Green Energy (OSTI)

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.

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

2009-09-02T23:59:59.000Z

164

Propagation of light in serially coupled plasmonic nanowire dimer: Geometry dependence and polarization control  

SciTech Connect

We experimentally studied plasmon-polariton-assisted light propagation in serially coupled silver nanowire (Ag-NW) dimers and probed their dependence on bending-angle between the nanowires and polarization of incident light. From the angle-dependence study, we observed that obtuse angles between the nanowires resulted in better transmission than acute angles. From the polarization studies, we inferred that light emission from junction and distal ends of Ag-NW dimers can be systematically controlled. Further, we applied this property to show light routing and polarization beam splitting in obtuse-angled Ag-NW dimer. The studied geometry can be an excellent test-bed for plasmonic circuitry.

Singh, Danveer; Raghuwanshi, Mohit; Pavan Kumar, G. V. [Photonics and Optical Nanoscopy Laboratory, Department of Physics and Department of Chemistry, Indian Institute of Science Education and Research (IISER), Pune 411008 (India)

2012-09-10T23:59:59.000Z

165

Behavior of molybdenum nitrides as materials for electrochemical capacitors: Comparison with ruthenium oxide  

Science Conference Proceedings (OSTI)

Ruthenium oxide (RuO{sub 2}), formed as a thin film on a Ru or Ti metal substrate, exhibits a large specific (cm{sup {minus}2}) and almost constant, electrochemical capacitance over a 1.35 V range in aqueous H{sub 2}SO{sub 4}. This behavior has led to its investigation and use as a material for fabrication of supercapacitor devices. However, its cost has encouraged search for other materials exhibiting similar behavior. Work reported in the present paper evaluates two nitrides of Mo, Mo{sub 2}N and MoN, as substitutes for RuO{sub 2}. It is shown that very similar capacitance behavior to that of RuO{sub 2} films arises, e.g., in cyclic voltammetry and dc charging curves; in the former, almost mirror-image anodic and cathodic current-response profiles, characteristic of a capacitor, arise. However, the nitride materials have a substantially smaller voltage operating range of only some 0.7 V due to electrochemical decomposition above ca. 0.7 V vs. RHE. This limits their usefulness as a substitute for RuO{sub 2}. Of interest is that the nitride films exhibit potential-decay and potential-recovery on open circuit after respective charge and forced discharge. The decay and recovery processes are logarithmic in time, indicating the role of internal faradaic charge redistribution processes.

Liu, T.C.; Pell, W.G.; Conway, B.E. [Univ. of Ottawa, Ontario (Canada). Dept. of Chemistry; Roberson, S.L. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering

1998-06-01T23:59:59.000Z

166

Mercury dimer spectroscopy and an Einstein-Podolsky-Rosen experiment  

E-Print Network (OSTI)

The dissociation of a 199Hg2 dimer prepares an entangled state of two spatially separated 199Hg atoms, each with nuclear spin 1/2, and with zero total electron and nuclear spin angular momenta. This is identical to the entangled state of the two spin 1/2 particles in Bohm’s classic version of the EPR gedankenexperiment. An analysis of the rotational structure of the CD=57HCI=0 band of the D3K+ u (1u)HX1Kg + (0+ g ) transition in Hg2 (natural abundance) is presented. The analysis of the fluorescence excitation spectrum using a dye laser gives the values of the constants BCD=57 and BCI=0 for the excited and ground electronic energy states involved in the transition, respectively. To increase the accuracy of the rotational constants and resolve the fine spectrum of the Hg2, a continuously tunable single longitudinal mode laser with ultra-narrow line-width is needed. Measurements using a narrow line-width alexandrite laser had been attempted and the values of BCD=57 and BCI=0 were determined. To improve the quality of the laser beam and hence the precision of the rotational constants, modifications have been made to the cavity of the alexandrite laser. This provides a possibility for further investigation.

Qu, Xinmei

2008-08-01T23:59:59.000Z

167

Quantum magnetism with polar alkali-metal dimers  

Science Conference Proceedings (OSTI)

We show that dipolar interactions between ultracold polar alkali-metal dimers in optical lattices can be used to realize a highly tunable generalization of the t-J model, which we refer to as the t-J-V-W model. The model features long-range spin-spin interactions J{sub z} and J{sub perpendicular} of XXZ type, long-range density-density interaction V, and long-range density-spin interaction W, all of which can be controlled in both magnitude and sign independently of each other and of the tunneling t. The spin's is encoded in the rotational degree of freedom of the molecules, while the interactions are controlled by applied static electric and continuous-wave microwave fields. Furthermore, we show that nuclear spins of the molecules can be used to implement an additional (orbital) degree of freedom that is coupled to the original rotational degree of freedom in a tunable way. The presented system is expected to exhibit exotic physics and to provide insights into strongly correlated phenomena in condensed-matter systems. Realistic experimental imperfections are discussed.

Gorshkov, Alexey V. [Institute for Quantum Information, California Institute of Technology, Pasadena, California 91125 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Manmana, Salvatore R.; Chen Gang [JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440 and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390 (United States); Demler, Eugene; Lukin, Mikhail D. [Physics Department, Harvard University, Cambridge, Massachusetts 02138 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Rey, Ana Maria [JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440 and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390 (United States); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States)

2011-09-15T23:59:59.000Z

168

Density functional theory study of the conductivity of the biphenalenyl radical dimer  

E-Print Network (OSTI)

We present ab initio molecular calculations at different levels of density functional theory (DFT) for the spiro-biphenalenyl neurtral radical in its singlet and triplet states. We performed calculations on the dimer to ...

Lu, Aiyan

2007-01-01T23:59:59.000Z

169

Synthesis and characterization of quinone-substituted octaalkyl porphyrin monomers and dimers  

SciTech Connect

The synthesis and characterization of a variety of selectively metalated quinone-substituted zinc-containing octaalkyl porphyrin dimers, designed to mimic certain key electronic and structural aspects of the photosynthetic reaction centers of Rhodopseudomonas viridis and Rhodobacter sphaeroides, and appropriate control monomers and dimers are described. These new compounds have been characterized by {sup 1}H NMR, {sup 13}C NMR, UV-visible spectroscopy, mass spectrometry, and microanalysis. Electrochemical data are also given for representative dimers and monomers and X-ray structural information is provided for a 1,3-phenyl-linked and a 1,4-phenyl-linked functionalized copper-containing dimer and for a quinone-substituted metal-free monomer.

Sessler, J.L.; Johnson, M.R.; Creager, S.E. (Univ. of Texas, Austin (United States)); Fettinger, J.C.; Ibers, J.A. (Northwestern Univ., Evanston, IL (United States))

1990-12-05T23:59:59.000Z

170

Nonlinear optical properties of porphyrin and chlorophyll dimers studied by degenerated four wave mixing  

Science Conference Proceedings (OSTI)

As one of the important elements in natural and artificial electron transfer and energy transfer processes, porphyrin and its derivatives have received much attention in photoelectronics and photoelectronic materials. As our first attempt to relate the {pi}-{pi} electronic couplings between porphyrin macrocycles to apparent third order nonlinear susceptibilities, we measured {chi}({sup 3}) for several porphyrin and chlorophyll a derivatives, including dimers with different configurations. Our preliminary results show that the dimers have enhanced {chi}({sup 3}) compared to those of the monomer. This enhancement is related to the relative orientations between the two macrocycles in the dimers. The parallel dimers with close face-to-face distances seem to have the highest enhancement in {chi}({sup 3}). Thus, we believe that {chi}({sup 3}) is strongly related to the {pi}-{pi} electronic coupling between the two conjugated ring systems.

Chen, L.X.Q.

1992-12-31T23:59:59.000Z

171

Nonlinear optical properties of porphyrin and chlorophyll dimers studied by degenerated four wave mixing  

SciTech Connect

As one of the important elements in natural and artificial electron transfer and energy transfer processes, porphyrin and its derivatives have received much attention in photoelectronics and photoelectronic materials. As our first attempt to relate the [pi]-[pi] electronic couplings between porphyrin macrocycles to apparent third order nonlinear susceptibilities, we measured [chi]([sup 3]) for several porphyrin and chlorophyll a derivatives, including dimers with different configurations. Our preliminary results show that the dimers have enhanced [chi]([sup 3]) compared to those of the monomer. This enhancement is related to the relative orientations between the two macrocycles in the dimers. The parallel dimers with close face-to-face distances seem to have the highest enhancement in [chi]([sup 3]). Thus, we believe that [chi]([sup 3]) is strongly related to the [pi]-[pi] electronic coupling between the two conjugated ring systems.

Chen, L.X.Q.

1992-01-01T23:59:59.000Z

172

Preparation and characterization of waterborne polyurethaneurea composed of dimer fatty acid polyester polyol  

Science Conference Proceedings (OSTI)

A series of polyurethaneurea (PUU) aqueous dispersions, which were stable at ambient temperature for more than 1 year, were prepared with C36-dimer-fatty-acid-based polyester polyol, isophorone diisocyanate, dimethylol propionic acid, and ...

2006-01-01T23:59:59.000Z

173

Electron transfer beyond the static picture: A TDDFT/TD-ZINDO study of a pentacene dimer  

SciTech Connect

We use time-dependent density functional theory and time-dependent ZINDO (a semi-empirical method) to study transfer of an extra electron between a pair of pentacene dimers. A measure of the electronic transfer integral is computed in a dynamic picture via the vertical excitation energy from a delocalized anionic ground state. With increasing dimer separation, this dynamical measurement of charge transfer is shown to be significantly larger than the commonly used static approximation (i.e., LUMO+1 - LUMO of the neutral dimer, or HOMO - LUMO of the charged dimer), up to an order of magnitude higher at 6 Å. These results offer a word of caution for calculations involving large separations, as in organic photovoltaics, where care must be taken when using a static picture to model charge transfer.

Reslan, Randa; Lopata, Kenneth A.; Arntsen, Christopher D.; Govind, Niranjan; Neuhauser, Daniel

2012-12-14T23:59:59.000Z

174

Catalysis and activation of magic states in fault-tolerant architectures  

Science Conference Proceedings (OSTI)

In many architectures for fault-tolerant quantum computing universality is achieved by a combination of Clifford group unitary operators and preparation of suitable nonstabilizer states, the so-called magic states. Universality is possible even for some fairly noisy nonstabilizer states, as distillation can convert many noisy copies into fewer purer magic states. Here we propose protocols that exploit multiple species of magic states in surprising ways. These protocols provide examples of previously unobserved phenomena that are analogous to catalysis and activation well known in entanglement theory.

Campbell, Earl T. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom) and Institute of Physics and Astronomy, University of Potsdam, D-14476 Potsdam (Germany)

2011-03-15T23:59:59.000Z

175

Pure-state transformations and catalysis under operations that completely preserve positivity of partial transpose  

E-Print Network (OSTI)

Motivated by the desire to better understand the class of quantum operations on bipartite systems that preserve positivity of partial transpose (PPT operations) and its relation to the class LOCC (local operations and classical communication), we present some results on deterministic bipartite pure state transformations by PPT operations. Restricting our attention to the case where we start with a rank K maximally entangled state, we give a necessary condition for transforming it into a given pure state, which we show is also sufficient when K is two and the final state has Schmidt rank three. We show that it is sufficient for all K and all final states provided a conjecture about a certain family of semidefinite programs is true. We also demonstrate that the phenomenon of catalysis can occur under PPT operations and that, unlike LOCC catalysis, a maximally entangled state can be a catalyst. Finally, we give a necessary and sufficient condition for the possibility of transforming a rank K maximally entangled state to an arbitrary pure state by PPT operations assisted by some maximally entangled catalyst.

William Matthews; Andreas Winter

2008-01-28T23:59:59.000Z

176

Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet  

NLE Websites -- All DOE Office Websites (Extended Search)

Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2011 J. Phys.: Condens. Matter 23 416003 (http://iopscience.iop.org/0953-8984/23/41/416003) Download details: IP Address: 128.219.49.9 The article was downloaded on 17/10/2011 at 17:07 Please note that terms and conditions apply. View the table of contents for this issue, or go to the journal homepage for more Home Search Collections Journals About Contact us My IOPscience IOP PUBLISHING JOURNAL OF PHYSICS: CONDENSED MATTER J. Phys.: Condens. Matter 23 (2011) 416003 (9pp) doi:10.1088/0953-8984/23/41/416003 Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet M B Stone 1 , A Podlesnyak 1 , G Ehlers

177

The retroviral RNA dimer linkage: different structures may reflect different roles  

E-Print Network (OSTI)

, Yamamoto N, Takaku H, Kawai G: NMR analysis of intra- and inter-molecular stems in the dimerization initiation site of the HIV-1 genome. J Bio- chem (Tokyo) 2000, 127:681-686. 48. Takahashi KI, Baba S, Chattopadhyay P, Koyanagi Y, Yamamoto N, Takaku H... ral ssBioMed CentRetrovirology Open AcceReview The retroviral RNA dimer linkage: different structures may reflect different roles Jane Greatorex* Address: Division of Infectious Diseases, Dept. of Medicine, University of Cambridge, Addenbrooke...

Greatorex, Jane S

2004-08-18T23:59:59.000Z

178

In situ control of As dimer orientation on Ge(100) surfaces  

Science Conference Proceedings (OSTI)

We investigated the preparation of single domain Ge(100):As surfaces in a metal-organic vapor phase epitaxy reactor. In situ reflection anisotropy spectra (RAS) of vicinal substrates change when arsenic is supplied either by tertiarybutylarsine or by background As{sub 4} during annealing. Low energy electron diffraction shows mutually perpendicular orientations of dimers, scanning tunneling microscopy reveals distinct differences in the step structure, and x-ray photoelectron spectroscopy confirms differences in the As coverage of the Ge(100):As samples. Their RAS signals consist of contributions related to As dimer orientation and to step structure, enabling precise in situ control over preparation of single domain Ge(100):As surfaces.

Brueckner, Sebastian; Doescher, Henning [Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Technische Universitaet Ilmenau, Institut fuer Physik, Postfach 10 05 65, 98684 Ilmenau (Germany); Supplie, Oliver; Luczak, Johannes [Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Barrigon, Enrique; Rey-Stolle, Ignacio [Instituto de Energia Solar, Universidad Politecnica de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Kleinschmidt, Peter [Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); CiS Forschungsinstitut fuer Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Strasse 14, 99099 Erfurt (Germany); Hannappel, Thomas [Helmholtz-Zentrum Berlin, Hahn-Meitner-Platz 1, 14109 Berlin (Germany); Technische Universitaet Ilmenau, Institut fuer Physik, Postfach 10 05 65, 98684 Ilmenau (Germany); CiS Forschungsinstitut fuer Mikrosensorik und Photovoltaik GmbH, Konrad-Zuse-Strasse 14, 99099 Erfurt (Germany)

2012-09-17T23:59:59.000Z

179

Catalysis Letters 59 (1999) 9394 93 Stepwise methane steam reforming: a route to CO-free hydrogen  

E-Print Network (OSTI)

Catalysis Letters 59 (1999) 93­94 93 Stepwise methane steam reforming: a route to CO-free hydrogen-free hydrogen. Keywords: methane decomposition, Ni/zirconia, steam gasification In order to utilize hydrogen of impurities, particularly carbon monoxide. Steam reforming, partial oxidation and au- tothermal reforming [1

Goodman, Wayne

180

Channeling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J. Fisch  

E-Print Network (OSTI)

, with electrons kept cold, so that the effective fusion reactivity can be increased [9­11]. The meansChanneling of Fusion Alpha-Particle Power Using Minority Ion Catalysis A. I. Zhmoginov and N. J greatly facilitate controlled nuclear fusion. The parameter range for achieving this temperature disparity

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181

Acid Catalysis in Basic Solution: A Supramolecular Host PromotesOrthoformate Hydrolysis  

DOE Green Energy (OSTI)

Though many enzymes can promote chemical reactions by tuning substrate properties purely through the electrostatic environment of a docking cavity, this strategy has proven challenging to mimic in synthetic host-guest systems. Here we report a highly-charged, water soluble, metal-ligand assembly with a hydrophobic interior cavity that thermodynamically stabilizes protonated substrates and consequently catalyzes the normally acidic hydrolysis of orthoformates in basic solution, with rate accelerations of up to 890-fold. The catalysis reaction obeys Michaelis-Menten kinetics, exhibits competitive inhibition, and the substrate scope displays size selectivity consistent with the constrained binding environment of the molecular host. Synthetic chemists have long endeavored to design host molecules capable of selectively binding slow-reacting substrates and catalyzing their chemical reactions. While synthetic catalysts are often site-specific and require certain properties of the substrate to insure catalysis, enzymes are often able to modify basic properties of the bound substrate such as pK{sub a} in order to enhance reactivity. Two common motifs used by nature to activate otherwise unreactive compounds are the precise arrangement of hydrogen-bonding networks and electrostatic interactions between the substrate and adjacent residues of the protein. Precise arrangement of hydrogen bonding networks near the active sites of proteins can lead to well-tuned pK{sub a}-matching, and can result in pK{sub a} shifts of up to eight units, as shown in bacteriorhodopsin. Similarly, purely electrostatic interactions can greatly favor charged states and have been responsible for pK{sub a} shifts of up to five units for acetoacetate decarboxylase. Attempts have been made to isolate the contributions of electrostatic versus covalent interactions to such pK{sub a} shifts; however this remains a difficult challenge experimentally. This challenge emphasizes the importance of synthesizing host molecules that, like enzyme cavities, can enhance binding of small molecular guests and, in a few cases, catalyze chemical reactions. Supramolecular assemblies with available functional groups have been used to generate solution-state pK{sub a} shifts of up to two pK{sub a} units and to catalyze chemical reactions. Synthetic hosts often rely on hydrogen-bonding or ion-dipole interactions for guest inclusion, and numerous studies have investigated the effects of charge on guest binding affinities in supramolecular host-guest systems. We report here a synthetic supramolecular host assembly that relies exclusively on electrostatic and hydrophobic interactions for thermodynamic stabilization of protonated substrates. As nature has exploited pK{sub a} shifts to activate otherwise unreactive substrates toward catalysis, this stabilization is exploited to promote acid-catalyzed hydrolyses in strongly basic solution.

Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

2007-12-12T23:59:59.000Z

182

Photoionization spectroscopy of ionic metal dimers: LiCu and LiAg  

Science Conference Proceedings (OSTI)

Electronic spectra are reported for the heteronuclear metal dimers LiCu and LiAg, with resonant one-color two-photon ionization (R2PI). The dimers are produced in a pulsed supersonic molecular beam by laser vaporization of either a copper or silver rod coated with a thin film of vacuum deposited lithium metal. A total of twelve excited electronic states for LiCu and seven for LiAg are observed. Analysis of the vibrational progressions yields ground and excited state vibrational frequencies and dissociation energies for both LiCu and LiAg. In addition, selected vibronic bands are rotationally resolved. This data, together with that obtained by Morse and co-workers for LiCu [J. Chem. Phys. (to be published)], gives bond lengths for LiCu and LiAg (r{sub 0}{sup {double_prime}}=2.26 and 2.41 {Angstrom}, respectively). The bond lengths for LiCu and LiAg are significantly shorter than expected by comparison to the homonuclear diatomics Li{sub 2} and Cu{sub 2} or Ag{sub 2}. Dissociation energies in the heteronuclear dimers are also much greater than the mean of the corresponding homonuclear dimer values. These trends indicate that ionic character plays a leading role in the ground-state bonding. {copyright} {ital 1997 American Institute of Physics.}

Brock, L.R.; Knight, A.M.; Reddic, J.E.; Pilgrim, J.S.; Duncan, M.A. [Department of Chemistry, University of Georgia, Athens, Georgia 30602 (United States)

1997-04-01T23:59:59.000Z

183

Structure of a Light-Activated LOV Protein Dimer That Regulates Transcription  

Science Conference Proceedings (OSTI)

Light, oxygen, or voltage (LOV) protein domains are present in many signaling proteins in bacteria, archaea, protists, plants, and fungi. The LOV protein VIVID (VVD) of the filamentous fungus Neurospora crassa enables the organism to adapt to constant or increasing amounts of light and facilitates proper entrainment of circadian rhythms. Here, we determined the crystal structure of the fully light-adapted VVD dimer and reveal the mechanism by which light-driven conformational change alters the oligomeric state of the protein. Light-induced formation of a cysteinyl-flavin adduct generated a new hydrogen bond network that released the amino (N) terminus from the protein core and restructured an acceptor pocket for binding of the N terminus on the opposite subunit of the dimer. Substitution of residues critical for the switch between the monomeric and the dimeric states of the protein had profound effects on light adaptation in Neurospora. The mechanism of dimerization of VVD provides molecular details that explain how members of a large family of photoreceptors convert light responses to alterations in protein-protein interactions.

Vaidya, Anand T.; Chen, Chen-Hui; Dunlap, Jay C.; Loros, Jennifer J.; Crane, Brian R. (Dartmouth-MED); (Cornell)

2012-10-25T23:59:59.000Z

184

Formation of clean dimers during gas-source growth of Si(001) D.R.Bowler  

E-Print Network (OSTI)

-source growth of Si(001) using hydrogen-based precursors (such as SiH 4 , silane, and Si 2 H 6 , disilane observations of the growth of Si(001) from disilane, both at room temperature following anneals 1 dimers, with the aim of explaining how these form at a comparatively low temperature. Disilane (which

Bowler, David

185

Argonne CNM Highlight: Gold nanoparticles create visible-light catalysis in  

NLE Websites -- All DOE Office Websites (Extended Search)

Silver chloride-gold nanoparticles Gold-coated silver chloride (AgCl) nanowires at the microscopic level. In the News United Press International | PhysOrg.com | R&D Magazine| Nanotechnology Now | Photonics.com Gold nanoparticles create visible-light catalysis in nanowires A two-step approach has been developed within the Nanophotonics Group to synthesize AgCl nanowires decorated with gold nanoparticles by using silver nanowires as chemical templates. In the first step, the silver nanowires are chemically oxidized and converted to AgCl nanowires. In the second step, ions generated in the first step reduce gold precursors (e.g., NaAuCl4) to deposit gold nanoparticles on the AgCl nanowire surfaces, resulting in the formation of AgCl:gold composite nanowires. Because of the

186

Metal-surface reaction energetics. Theory and application to heterogeneous catalysis, chemisorption, and surface diffusion  

SciTech Connect

The title is esoteric. The subtitle is specialized. This is an edited book containing five chapters written by eight authors. It is not a book to read from beginning to end, but kept perusing this handsomely printed and well-edited volume, learned so much that he wishes to convey his message to a small but very successful group of chemists and chemical engineers in heterogeneous catalysis: there is a lot to learn in this book, not so much in theory but in the facts that the theorists who wrote the book are trying to explain today with the faint hope that tomorrow they will actually predict new chemistry in as yet unknown catalytic cycles.

Shustorovich, E. (ed.)

1991-01-01T23:59:59.000Z

187

Enantioselective Catalysis of the Aza-Cope Rearrangement by a Chiral Supramolecular Assembly  

SciTech Connect

The chiral supramolecular catalyst Ga{sub 4}L{sub 6} [L = 1,5-bis(2,3-dihydroxybenzoylamino)naphthalene] is a molecular tetrahedron that catalyzes the 3-aza-Cope rearrangement of allyl enammonium cations. This catalysis is accomplished by preorganizing the substrate in a reactive conformation within the host. This work demonstrates that through the use of enantiopure assembly, its chiral cavity is capable of catalyzing the 3-aza-Cope rearrangement enantioselectively, with yields of 21-74% and enantiomeric excesses from 6 to 64% at 50 C. At lower temperatures, the enantioselectivity improved, reaching 78% ee at 5 C. This is the highest enantioselectivity to date induced by the chiral cavity of a supramolecular assembly.

Brown, Casey J.; Bergman, Robert G.; Raymond, Kenneth N.

2009-07-29T23:59:59.000Z

188

Superacid catalysis of light hydrocarbon conversion. Sixth quarterly report, January 1, 1995--March 31, 1995  

DOE Green Energy (OSTI)

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. Perhaps more active catalysts will be useful for propane conversion. The propane conversion data reported here provide excellent insights into the chemistry of the catalytic conversions; they are consistent with the inference that the catalyst is a superacid and that the chemistry is analogous to. that determined in superacid solutions by G.A. Olah, who was awarded the most recent Nobel Prize in chemistry for his work. The catalyst was tested for conversion of propane at 1 bar, 200--300{degrees}C and propane partial pressures in the range of 0.01--0.05 bar. At 250{degrees}C, catalysis was demonstrated, as the number of propane molecules converted was at least 1 per sulfate group after 16 days of operation in a continues flow reactor. Propane was converted in high yield to butanes, but the conversions were low, for example being only a fraction of a percent at a space velocity of 9.1 {times} 10{sup {minus}7} mol(g of catalysis {center_dot} s) and 250{degrees}C. Coke formation was rapid. 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.

Gates, B.C. [California Univ., Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

1995-08-01T23:59:59.000Z

189

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  

Science Conference Proceedings (OSTI)

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.

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

2011-11-23T23:59:59.000Z

190

Role of hydrous ruthenium oxide in Pt-Ru direct methanol fuel cell anode electrocatalysts: The importance of mixed electron/proton conductivity  

Science Conference Proceedings (OSTI)

Pt-Ru is the favored anode catalyst for the oxidation of methanol in direct methanol fuel cells (DMFCs). The nanoscale Pt-Ru blacks are accepted to be bimetallic alloys as based on their X-ray diffraction patterns. These bulk and surface analyses show that although practical Pt-Ru blacks have diffraction patterns consistent with an alloy assignment, they are primarily a mix of Pt metal and Ru oxides plus some Pt oxides and only small amounts of Ru metal. Thermogravimetric analysis and X-ray photoelectron spectroscopy of as-received Pt-Ru electrocatalysts indicate that DMFC materials contain substantial amounts of hydrous ruthenium oxide (RuO{sub x}H{sub y}). A potential misidentification of nanoscale Pt-Ru blacks arises because RuO{sub x}H{sub y} is amorphous and cannot be discerned by X-ray diffraction. Hydrous ruthenium oxide is a mixed proton and electron conductor and innately expresses Ru-OH speciation. These properties are of key importance in the mechanism of methanol oxidation, in particular, Ru-OH is a critical component of the bifunctional mechanism proposed for direct methanol oxidation in that it is the oxygen-transfer species that oxidatively dissociates {single_bond}C{triple_bond}O fragments from the Pt surface. The catalysts and membrane-electrode assemblies of DMFCs should not be processed at or exposed to temperatures >150 C, as such conditions deleteriously lower the proton conductivity of hydrous ruthenium oxide and thus affect the ability of the Ru component of the electrocatalyst to dissociate water. With this analytical understanding of the true nature of practical nanoscale Pt-Ru electrocatalysts, the authors can now recommend that hydrous ruthenium oxide, rather than Ru metal or anhydrous RuO{sub 2}, is the preferred Ru speciation in these catalysts.

Rolison, D.R.; Hagans, P.L.; Swider, K.E.; Long, J.W. [Naval Research Lab., Washington, DC (United States). Surface Chemistry Branch

1999-02-02T23:59:59.000Z

191

Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

Parametric Gasification of Oak Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis Jason Hrdlicka, Calvin Feik, Danny Carpenter, and Marc Pomeroy Technical Report NREL/TP-510-44557 December 2008 Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis Jason Hrdlicka, Calvin Feik, Danny Carpenter, and Marc Pomeroy Prepared under Task No. H2713B13 Technical Report NREL/TP-510-44557 December 2008 National Renewable Energy Laboratory 1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 * www.nrel.gov 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

192

Mesoporous Silica Nanomaterials for Applications in Catalysis, Sensing, Drug Delivery and Gene Transfection  

SciTech Connect

The central theme of this dissertation is represented by the versatility of mesoporous silica nanomaterials in various applications such as catalysis and bio-applications, with main focus on biological applications of Mesoporous Silica Nanospheres (MSN). The metamorphosis that we impose to these materials from catalysis to sensing and to drug and gene delivery is detailed in this dissertation. First, we developed a synthetic method that can fine tune the amount of chemically accessible organic functional groups on the pores surface of MSN by exploiting electrostatic and size matching between the cationic alkylammonium head group of the cetyltrimethylammonium bromide (CTAB) surfactant and various anionic organoalkoxysilane precursors at the micelle-water interface in a base-catalyzed condensation reaction of silicate. Aiming nature imitation, we demonstrated the catalytic abilities of the MSNs, We utilized an ethylenediamine functional group for chelating Cu{sup 2+} as a catalytic functional group anchored inside the mesopores. Thus, a polyalkynylene-based conducting polymer (molecular wire) was synthesized within the Cu-functionalized MSNs silica catalyst. For sensing applications, we have synthesized a poly(lactic acid) coated mesoporous silica nanosphere (PLA-MSN) material that serves as a fluorescence sensor system for detection of amino-containing neurotransmitters in neutral aqueous buffer. We exploited the mesoporosity of MSNs for encapsulating pharmaceutical drugs. We examined bio-friendly capping molecules such as polyamidoamine dendrimers of generations G2 to G4, to prevent the drug leaching. Next, the drug delivery system employed MSNs loaded with Doxorubicin, an anticancer drug. The results demonstrated that these nano-Trojan horses have ability to deliver Doxorubicin to cancer cells and induce their death. Finally, to demonstrate the potential of MSN as an universal cellular transmembrane nanovehicle, we anchored positively charged dendrimers on the surface of MSN and utilize them to complex cationic DNA. The p-EGFP-CI gene-coated MSN nanocomposite was able to transfect cancer cell lines, such as human HeLa and CHO cancer cell lines. The gene carrier ability of MSNs was further proved by transfecting primary cells and cotransfecting of two different genes in cancer cell lines. In sum, MSN are versatile partners in several types of applications.

Daniela Rodica Radu

2005-12-19T23:59:59.000Z

193

Electron-nuclear correlations for photo-induced dynamics in molecular dimers  

E-Print Network (OSTI)

Ultrafast photoinduced dynamics of electronic excitation in molecular dimers is drastically affected by the dynamic reorganization of inter- and intra- molecular nuclear configuration modeled by a quantized nuclear degree of freedom [Cina et. al, J. Chem Phys. {118}, 46 (2003)]. The dynamics of the electronic population and nuclear coherence is analyzed by solving the chain of coupled differential equations for %mean coordinate, population inversion, electron-vibrational correlation, etc. [Prezhdo, Pereverzev, J. Chem. Phys. {113} 6557 (2000)]. Intriguing results are obtained in the approximation of a small change of the nuclear equilibrium upon photoexcitation. In the limiting case of resonance between the electronic energy gap and the frequency of the nuclear mode these results are justified by comparison to the exactly solvable Jaynes-Cummings model. It is found that the photoinduced processes in the model dimer are arranged according to their time scales: (i) fast scale of nuclear motion, (ii) intermediate scale of dynamical redistribution of electronic population between excited states as well as growth and dynamics of electron-nuclear correlation, (iii) slow scale of electronic population approach to the quasi-equilibrium distribution, decay of electron-nuclear correlation, and decrease of the amplitude of mean coordinate oscillation. The latter processes are accompanied by a noticeable growth of the nuclear coordinate dispersion associated with the overall nuclear wavepacket width. The demonstrated quantum relaxation features of the photoinduced vibronic dynamics in molecular dimers are obtained by a simple method, applicable to systems with many degrees of freedom.

Dmitri S. Kilin; Yuri V. Pereversev; Oleg V. Prezhdo

2004-03-13T23:59:59.000Z

194

Steam catalysis in CaO carbonation under low steam partial pressure  

Science Conference Proceedings (OSTI)

CaO was widely used to capture CO{sub 2} in direct hydrogen production process, where steam always existed simultaneously. The effect of steam on CaO carbonation performance under low steam partial pressure was investigated using a pressurized thermogravimetric apparatus. The experimental results revealed that steam improved CaO carbonation performance significantly no matter whether Ca(OH){sub 2} was produced or not. At 823 K and 0.5 MPa of steam partial pressure, effect of steam on CaO carbonation performance could not be attributed mainly to production of Ca(OH){sub 2} because the hydration rate of CaO was very slow. The main reason was steam catalysis in CaO carbonation. Enhancement of steam on CaO carbonation performance without Ca(OH){sub 2} production could not be attributed to improvement of steam on the physical property, but to catalytic effect of steam. Effects of CaO precursors, CO{sub 2} partial pressure, steam partial pressure, and temperature with steam addition on CaO carbonation performance were also investigated.

Yang, S.J.; Xiao, Y.H. [Chinese Academy of Science, Beijing (China)

2008-06-15T23:59:59.000Z

195

Hydrogen and methane syntheses through radiation catalysis. Progress report, June 1, 1977--August 31, 1978  

DOE Green Energy (OSTI)

Preliminary testing was performed of the concept of an electronic theory of catalysis to relate electrical properties of the catalysts to increased rates in radiation-induced reactions. The first system selected for study was the radiolysis of water as stimulated by absorption of gamma radiation, a system that has been thoroughly tested by numerous workers all in excellent agreement. Early results indicate a significant correspondence between hydrogen gas yield and the forbidden band gap (Eg) of the catalyst substrate, when Eg approximates the energy of the hydrogen-oxygen bond in the water molecule. Catalysts tested were TiO/sub 2/, SrTiO/sub 3/, Sb/sub 2/O/sub 3/, MoO/sub 3/, Nb/sub 2/O/sub 5/, SnO/sub 2/, CaO, HfO/sub 2/, In/sub 2/O/sub 3/, and V/sub 2/O/sub 5/. Equipment to measure dielectric properties of solids has been built and calibrated, and will now be applied to pre- and post-irradiation testing of the catalysts used. Separate abstracts were prepared for the appendices: one a review of existing analytical models of photoelectrochemical cells and the other a theoretical modeling of semiconductor-electrolyte interfaces.

Morse, J G

1978-09-01T23:59:59.000Z

196

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

Science Conference Proceedings (OSTI)

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.

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.

2011-05-24T23:59:59.000Z

197

THE EFFECT OF SULFUR ON METHANE PARTIAL OXIDATION AND REFORMING PROCESSES FOR LEAN NOX TRAP CATALYSIS  

Science Conference Proceedings (OSTI)

Lean NOx trap catalysis has demonstrated the ability to reduce NOx emissions from lean natural gas reciprocating engines by >90%. The technology operates in a cyclic fashion where NOx is trapped on the catalyst during lean operation and released and reduced to N2 under rich exhaust conditions; the rich cleansing operation of the cycle is referred to as "regeneration" since the catalyst is reactivated for more NOx trapping after NOx purge. Creating the rich exhaust conditions for regeneration can be accomplished by catalytic partial oxidation of methane in the exhaust system. Furthermore, catalytic reforming of partial oxidation exhaust can enable increased quantities of H2 which is an excellent reductant for lean NOx trap regeneration. It is critical to maintain clean and efficient partial oxidation and reforming processes to keep the lean NOx trap functioning properly and to reduce extra fuel consumption from the regeneration process. Although most exhaust constituents do not impede partial oxidation and reforming, some exhaust constituents may negatively affect the catalysts and result in loss of catalytic efficiency. Of particular concern are common catalyst poisons sulfur, zinc, and phosphorous. These poisons form in the exhaust through combustion of fuel and oil, and although they are present at low concentrations, they can accumulate to significant levels over the life of an engine system. In the work presented here, the effects of sulfur on the partial oxidation and reforming catalytic processes were studied to determine any durability limitations on the production of reductants for lean NOx trap catalyst regeneration.

Parks, II, James E [ORNL; Ponnusamy, Senthil [ORNL

2006-01-01T23:59:59.000Z

198

Cluster reactions: An approach to understanding the fundamentals of heterogeneous catalysis  

DOE Green Energy (OSTI)

The physical basis for catalysis is not well understood and the motivation for this ongoing research is to provide a basis for unraveling the role which composition, morphology and electronic states have on the functioning of catalysts for various classes of reactions. The work during the first two and one-half year grant period has focused on unsupported clusters of selected composition, charge state, and size. Research has proceeded along three general lines of inquiry: (1) investigation of the reactivity of these cluster materials and determination of the influence of their charged state; (2) determination of the kinetics of association (adsorption) of various reactants and unraveling the mechanisms of certain oxidation reactions known to be catalyzed on metal cluster alloys, oxides and carbides, and (3) thermochemical measurement of the absorption of gaseous species onto alloy and metal oxide and carbide cluster systems. The authors have pursued the role of metal and metal-oxide clusters, and the charge states of these, as they function to influence the reactions of adsorbed species including ammonia, alcohols, water, NO{sub x}, as well as CO and hydrogen. Evidence has been obtained that small positively charged nickel clusters function to catalyze reactions between adsorbed CO and hydrogen. In supportive studies, they have investigated the clustering of ammonia, methanol and water to nickel clusters of varying size. These studies, in conjunction with density functional calculations which are in progress, provide insight into cluster structures and knowledge of adsorption energies.

Castleman, A.W. Jr.

1994-11-01T23:59:59.000Z

199

Construction of narrow-band regenerative amplifier for momentum imaging spectroscopy of lithium dimer  

Science Conference Proceedings (OSTI)

We constructed a Ti:Sapphire narrow-band regenerative amplifier as the probe laser of the experiment of momentum imaging spectroscopy of lithium dimer. The spectral profile of the regenerative cavity was designed by three birefringent filters and a plate of etalon. With 1.1-mJ pumping by the second harmonics of Nd:YLF laser, mode-locked seed pulses were amplified to {approx}25 {mu}J at 1-kHz repetition, with the bandwidth of {approx}0.7 cm{sup -1}.

Matsuoka, Leo; Hashimoto, Masashi; Yokoyama, Keiichi [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7, Umemidai, Kizugawa, Kyoto 619-0215 (Japan)

2012-07-11T23:59:59.000Z

200

Directed transport in equilibrium : analysis of the dimer model with inertial terms  

E-Print Network (OSTI)

We have previously shown an analysis of our dimer model in the over-damped regime to show directed transport in equilibrium. Here we analyze the full model with inertial terms present to establish the same result. First we derive the Fokker-Planck equation for the system following a Galilean transformation to show that a uniformly translating equilibrium distribution is possible. Then, we find out the velocity selection for the centre of mass motion using that distribution on our model. We suggest generalization of our calculations for soft collision potentials and indicate to interesting situation with possibility of oscillatory non-equilibrium state within equilibrium.

A. Bhattacharyay

2011-08-15T23:59:59.000Z

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201

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

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.

Stuart L. Soled and Nancy Ryan Gray

2009-01-01T23:59:59.000Z

202

Voltammetric characterization of ruthenium oxide-based aerogels and other RuO{sub 2} solids: The nature of capacitance in nanostructured materials  

Science Conference Proceedings (OSTI)

Ruthenium dioxide is an important electrode material for applications in electrocatalysis and power sources. High surface areas are achieved in hydrous RuO{sub 2} precipitates and in mixed ruthenium oxide-titanium oxide, (Ru-Ti)O{sub x}, aerogels ( in which nanoscale domains are networked to form a highly porous structure). The electrochemical properties of (Ru-Ti)O{sub x} aerogels, RuO{sub 2}, and hydrous RuO{sub 2} are examined by direct pressing of sub-milligram quantities of the solid onto the surface of a conductive carbon/wax composite. Voltammetric measurements in acidic electrolyte confirm a pseudocapacitive response for all the RuO{sub x}-based materials. Despite an improvement in BET surface area, as compared with other RuO{sub 2} materials, the (Ru-Ti)O{sub x} aerogel displays a low specific capacitance, which correlated to the high degree of crystallinity of the aerogel. Nanocrystallites of rutile RuO{sub 2}, formed during thermal treatment of the sol-gel Ru/Ti precursors, deleteriously affect the specific capacitance of the material; however, all RuO{sub x} domains in the aerogel are voltammetrically addressable. The influence of proton-donating species on the observed capacitance for the (Ru-Ti)O{sub x} aerogel is evident from the dependence of the voltammetric charge in acidic electrolyte on the potential scan rate.

Long, J.W.; Swider, K.E.; Merzbacher, C.I.; Rolison, D.R. [Naval Research Lab., Washington, DC (United States)

1999-02-02T23:59:59.000Z

203

Coherent excitation-energy transfer and quantum entanglement in a dimer  

E-Print Network (OSTI)

We study coherent energy transfer of a single excitation and quantum entanglement in a dimer, which consists of a donor and an acceptor modeled by two two-level systems. Between the donor and the acceptor, there exists a dipole-dipole interaction, which provides the physical mechanism for coherent energy transfer and entanglement generation. The donor and the acceptor couple to two independent heat baths with diagonal couplings that do not dissipate the energy of the non-coupling dimer. Special attention is paid to the effect on single-excitation energy transfer and entanglement generation of the energy detuning between the donor and the acceptor and the temperatures of the two heat baths. It is found that, the probability for single-excitation energy transfer largely depends on the energy detuning in the low temperature limit. Concretely, the positive and negative energy detunings can increase and decrease the probability at the steady state, respectively. In the high temperature limit, however, the effect of the energy detuning on the probability is neglectably small. We also find that the probability is neglectably dependent on the bath temperature difference of the two heat baths. In addition, it is found that quantum entanglement can be generated in the process of coherent energy transfer. As the bath temperature increases, the generated steady state entanglement decreases. For a given bath temperature, the steady-state entanglement decreases with the increasing of the absolute value of the energy detuning.

Jie-Qiao Liao; Jin-Feng Huang; Le-Man Kuang; C. P. Sun

2010-05-12T23:59:59.000Z

204

Computational Mechanistic Studies of Acid-Catalyzed Lignin Model Dimers for Lignin Depolymerization  

Science Conference Proceedings (OSTI)

Lignin is a heterogeneous alkyl-aromatic polymer that constitutes up to 30% of plant cell walls, and is used for water transport, structure, and defense. The highly irregular and heterogeneous structure of lignin presents a major obstacle in the development of strategies for its deconstruction and upgrading. Here we present mechanistic studies of the acid-catalyzed cleavage of lignin aryl-ether linkages, combining both experimental studies and quantum chemical calculations. Quantum mechanical calculations provide a detailed interpretation of reaction mechanisms including possible intermediates and transition states. Solvent effects on the hydrolysis reactions were incorporated through the use of a conductor-like polarizable continuum model (CPCM) and with cluster models including explicit water molecules in the first solvation shell. Reaction pathways were computed for four lignin model dimers including 2-phenoxy-phenylethanol (PPE), 1-(para-hydroxyphenyl)-2-phenoxy-ethanol (HPPE), 2-phenoxy-phenyl-1,3-propanediol (PPPD), and 1-(para-hydroxyphenyl)-2-phenoxy-1,3-propanediol (HPPPD). Lignin model dimers with a para-hydroxyphenyl ether (HPPE and HPPPD) show substantial differences in reactivity relative to the phenyl ether compound (PPE and PPPD) which have been clarified theoretically and experimentally. The significance of these results for acid deconstruction of lignin in plant cell walls will be discussed.

Kim, S.; Sturgeon, M. R.; Chmely, S. C.; Paton, R. S.; Beckham, G. T.

2013-01-01T23:59:59.000Z

205

Ultrafast deactivation processes in the 2-aminopyridine dimer and the adenine-thymine base pair: Similarities and differences  

SciTech Connect

2-aminopyridine dimer has frequently been used as a model system for studying photochemistry of DNA base pairs. We examine here the relevance of 2-aminopyridine dimer for a Watson-Crick adenine-thymine base pair by studying UV-light induced photodynamics along two main hydrogen bridges after the excitation to the localized {sup 1}{pi}{pi}* excited-state. The respective two-dimensional potential-energy surfaces have been determined by time-dependent density functional theory with Coulomb-attenuated hybrid exchange-correlation functional (CAM-B3LYP). Different mechanistic aspects of the deactivation pathway have been analyzed and compared in detail for both systems, while the related reaction rates have also be obtained from Monte Carlo kinetic simulations. The limitations of the 2-aminopyridine dimer as a model system for the adenine-thymine base pair are discussed.

Ai Yuejie; Zhang Feng [College of Chemistry, Beijing Normal University, Beijing 100875 (China); Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, S-10691 Stockholm (Sweden); Cui Ganglong; Fang Weihai [College of Chemistry, Beijing Normal University, Beijing 100875 (China); Luo Yi [Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, S-10691 Stockholm (Sweden); Department of Chemical Physics, Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2010-08-14T23:59:59.000Z

206

Dendrimer-encapsulated metal nanoparticles: synthesis, characterization, and applications to catalysis  

E-Print Network (OSTI)

The research in this dissertation examines the chemistry and applications of dendrimers in homogeneous catalysis. We examined interactions between dendrimers and charged probe molecules, prepared dendrimer-encapsulated metal nanoparticles in organic solvents, studied size-selectivity of dendrimer-encapsulted catalysts, and designed molecular rulers as in-situ probes to measure the location of dendrimer-encapsulted metal nanoparticles. The intrinsic proton binding constant and a constant that characterizes the strength of electrostatic interactions among occupied binding sites in poly(amidoamine) (PAMAM) dendrimers have been obtained by studying the effect of solution pH on the protonation of the dendrimers. The significant finding is that these two factors are greatly modulated by the unique and hydrophobic microenvironment in the dendrimer interior. Hydrophilic poly(propylene imine) (PPI) dendrimers were modified with various hydrophobic alkyl chains through an amide linkage and were then used as templates for preparing intradendrimer copper nanoclusters. The main driving force for encapsulating metal-ions was found to be the differences in metal-ion solubility between the solvent and the interior of the dendrimer. Nanometer-sized metal particles are synthesized and encapsulated into the interior of dendrimers by first mixing together the dendrimer and metal ion solution and then reducing the composite chemically, and the resulting dendrimer-encapsulated metal nanoparticles can then be used as catalysts. By controlling the packing density on the dendrimer periphery using either different dendrimer generations or dendrimer surface functionalities, it is possible to control access of substrates to the encapsulated catalytic nanoparticle. Molecular rulers consisting of a large molecular "stopper", a reactive probe and a linker were designed as in-situ probes for determining the average distance between the surface of dendrimer-encapsulated palladium nanoparticles and the periphery of their fourth-generation, hydroxyl-terminated PAMAM dendrimer hosts. By doing so, we avoid having to make assumptions about the nanoparticle size and shape. The results suggest that the surface of the encapsulated nanoparticle is situated 0.7 ± 0.2 nm from the surface of the dendrimer.

Niu, Yanhui

2003-05-01T23:59:59.000Z

207

Studies toward biomimetic claisen condensation using nucleic acid templates and ribozyme catalysis  

E-Print Network (OSTI)

Many different experimental approaches were attempted to achieve carbon-carbon bond formation by nucleic acid template-directed reactions and ribozyme catalysis as potential lipid synthesizing machineries in the RNA world. A novel biomimetic condition for decarboxylative Claisen condensation in polyketide biosynthesis was discovered. The reaction of a malonic acid half oxyester with a Nhydroxysuccinmidyl ester forming reagent resulted in self-condensation to provide the corresponding 1,3-acetonedicarboxylic acid diester in the absence of a divalent metal chelator or a coordinating solvent. The decarboxylative Claisen condensation of malonyl adenosine using a poly-U template in solution or with immobilized poly-U was attempted. Various analytical methods demonstrated that malonyl adenosine underwent an exclusive hydrolysis reaction instead of condensation in the given conditions. Similar results were observed for the reaction of malonyl-CoA with acetyl-CoA on poly-U templates. No evidence for the decarboxylative Claisen condensation was observed by a DNA-templated system although a double helical structure of DNA duplex was proven to facilitate a bimolecular reaction by offering a favorable proximity effect. Therefore, it seems that the unsuccessful condensation resulted not from the bad template effect but from the intrinsic properties of the decarboxylative Claisen condensation reaction itself. Two tRNA molecules loaded with a malonic acid were prepared by ligation of truncated tRNAs with malonylated dinucletides. Our initial attempts to probe carbon-carbon bond formation by subjecting malonylated tRNAs to the in vitro translational machinery were not successful. Novel carbon isosteres of ?-amino acids are suggested as a potential source of a more stable and reactive carbanion for future experiments. Isoprenoid conjugates of nucleoside 5??-diphosphates, which were proposed as either an initiator nucleotide or substrate molecule for in vitro selection of prenyl-transferase ribozyme were prepared by one step nucleophilic displacement reactions. A random DNA pool was constructed for selection of a ketosynthase ribozyme. A substrate bearing a biotin tag was prepared by one-step conjugation. Hig-tagged T7 RNA polymerase was expressed and purified for a large scale transcription reaction. In vitro transcription of the random DNA pool with a 5??-thiol modified GMP analogue as an initiator nucleotide produced a thiol-modified random RNA library.

Ryu, Youngha

2003-05-01T23:59:59.000Z

208

One pyrimidine dimer inactivates expression of a transfected gene in xeroderma pigmentosum cells  

SciTech Connect

The authors have developed a host cell reactivation assay of DNA repair utilizing UV-treated plasmid vectors. The assay primarily reflects cellular repair of transcriptional activity of damaged DNA measured indirectly as enzyme activity of the transfected genes. They studied three plasmids (pSV2cat, 5020 base pairs; pSV2catSVgpt, 7268 base pairs; and pRSVcat, 5027 base pairs) with different sizes and promoters carrying the bacterial cat gene (CAT, chloramphenicol acetyltransferase) in a construction that permits cat expression in human cells. All human simian virus 40-transformed cells studied expressed high levels of the transfected cat gene. UV treatment of the plasmids prior to transfection resulted in differential decrease in CAT activity in different cell lines. With pSV2catSVgpt, UV inactivation of CAT expression was greater in the xeroderma pigmentosum group A and D lines than in the other human cell lines tested. The D0 of the CAT inactivation curve was 50 J X m-2 for pSV2cat and for pRSVcat in the xeroderma pigmentosum group A cells. The similarity of the D0 data in the xeroderma pigmentosum group A cells for three plasmids of different size and promoters implies they all have similar UV-inactivation target size. UV-induced pyrimidine dimer formation in the plasmids was quantified by assay of the number of UV-induced T4 endonuclease V-sensitive sites. In the most sensitive xeroderma pigmentosum cells, with all three plasmids, one UV-induced pyrimidine dimer inactivates a target of about 2 kilobases, close to the size of the putative CAT mRNA.

Protic-Sabljic, M.; Kraemer, K.H.

1985-10-01T23:59:59.000Z

209

SELECTIVE REDUCTION OF NOX IN OXYGEN RICH ENVIRONMENTS WITH PLASMA-ASSISTED CATALYSIS: CATALYST DEVELOPMENT AND MECHANISTIC STUDIES  

DOE Green Energy (OSTI)

The control of NOx (NO and NO2) emissions from so-called ''lean-burn'' vehicle engines remains a challenge. In recent years, there have been a number of reports that show that a plasma device combined with a catalyst can reduce as high as 90% or more of NOx in simulated diesel and other ''lean-burn'' exhaust. In the case of propylene containing simulated diesel exhaust, the beneficial role of a plasma treatment is now thought to be due to oxidation of NO to NO2, and the formation of partially oxidized hydrocarbons that are more active for the catalytic reduction of NO2 than propylene. Thus, the overall system can be most usefully described as hydrocarbon selective catalytic reduction (SCR) enhanced by 'reforming' the exhaust with a non-thermal plasma (NTP) device. For plasma-enhanced catalysis, both zeolite- and alumina-based materials have shown high activity, albeit in somewhat different temperature ranges, when preceded by an NTP reactor. This paper will briefly describe our research efforts aimed at optimizing the catalyst materials for NTP-catalysis devices based, in part, on our continuing studies of the NTP- and catalytic-reaction mechanisms. Various alkali- and alkaline earth-cation-exchanged Y zeolites have been prepared, their material properties characterized, and they have been tested as catalytic materials for NOx reduction in laboratory NTP-catalysis reactors. Interestingly, NO2 formed in the plasma and not subsequently removed over these catalysts, will back-convert to NO, albeit to varying extents depending upon the nature of the cation. Besides this comparative reactivity, we will also discuss selected synthesis strategies for enhancing the performance of these zeolite-based catalyst materials. A particularly important result from our mechanistic studies is the observation that aldehydes, formed during the plasma treatment of simulated diesel exhaust, are the important species for the reduction of NOx to N2. Indeed, acetaldehyde has been found to be especially effective in the thermal reduction of both NO and NO2 over Ba- and Na-Y zeolite catalysts.

Peden, C; Barlow, S; Hoard, J; Kwak, J; *Balmer-Millar, M; *Panov, A; Schmieg, S; Szanyi, J; Tonkyn, R

2003-08-24T23:59:59.000Z

210

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

Science Conference Proceedings (OSTI)

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.

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)

2012-08-27T23:59:59.000Z

211

Competitive fragmentation pathways of acetic acid dimer explored by synchrotron VUV photoionization mass spectrometry and electronic structure calculations  

Science Conference Proceedings (OSTI)

In present study, photoionization and dissociation of acetic acid dimers have been studied with the synchrotron vacuum ultraviolet photoionization mass spectrometry and theoretical calculations. Besides the intense signal corresponding to protonated cluster ions (CH{sub 3}COOH){sub n}{center_dot}H{sup +}, the feature related to the fragment ions (CH{sub 3}COOH)H{sup +}{center_dot}COO (105 amu) via {beta}-carbon-carbon bond cleavage is observed. By scanning photoionization efficiency spectra, appearance energies of the fragments (CH{sub 3}COOH){center_dot}H{sup +} and (CH{sub 3}COOH)H{sup +}{center_dot}COO are obtained. With the aid of theoretical calculations, seven fragmentation channels of acetic acid dimer cations were discussed, where five cation isomers of acetic acid dimer are involved. While four of them are found to generate the protonated species, only one of them can dissociate into a C-C bond cleavage product (CH{sub 3}COOH)H{sup +}{center_dot}COO. After surmounting the methyl hydrogen-transfer barrier 10.84 {+-} 0.05 eV, the opening of dissociative channel to produce ions (CH{sub 3}COOH){sup +} becomes the most competitive path. When photon energy increases to 12.4 eV, we also found dimer cations can be fragmented and generate new cations (CH{sub 3}COOH){center_dot}CH{sub 3}CO{sup +}. Kinetics, thermodynamics, and entropy factors for these competitive dissociation pathways are discussed. The present report provides a clear picture of the photoionization and dissociation processes of the acetic acid dimer in the range of the photon energy 9-15 eV.

Guan Jiwen; Hu Yongjun; Zou Hao [MOE Key laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631 (China); Cao Lanlan; Liu Fuyi; Shan Xiaobin; Sheng Liusi [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China)

2012-09-28T23:59:59.000Z

212

Investigation of the release of Si from SiO{sub 2} during the formation of manganese/ruthenium barrier layers  

SciTech Connect

The thermodynamic and structural stability of ruthenium-manganese diffusion barriers on SiO{sub 2} is assessed. A {approx}2 nm film composed of partially oxidized manganese (MnO{sub x} where x < 1) was deposited on a 3 nm thick Ru film and the Mn-MnO{sub x}/Ru/SiO{sub 2} structure was subsequently thermally annealed. X-ray photoelectron spectroscopy and secondary ion mass spectroscopy studies suggest the release and upward diffusion of Si from the dielectric substrate as a result of manganese-silicate formation at the Ru/SiO{sub 2} interface. The migration of Si up through the Ru film results in further manganese-silicate formation upon its interaction with the Mn-MnO{sub x} deposited layer.

McCoy, A. P.; Casey, P.; Bogan, J.; Byrne, C.; Hughes, G. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)] [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland)

2013-05-20T23:59:59.000Z

213

Chemical and structural investigations of the incorporation of metal manganese into ruthenium thin films for use as copper diffusion barrier layers  

Science Conference Proceedings (OSTI)

The incorporation of manganese into a 3 nm ruthenium thin-film is presented as a potential mechanism to improve its performance as a copper diffusion barrier. Manganese ({approx}1 nm) was deposited on an atomic layer deposited Ru film, and the Mn/Ru/SiO{sub 2} structure was subsequently thermally annealed. X-ray photoelectron spectroscopy studies reveal the chemical interaction of Mn with the SiO{sub 2} substrate to form manganese-silicate (MnSiO{sub 3}), implying the migration of the metal through the Ru film. Electron energy loss spectroscopy line profile measurements of the intensity of the Mn signal across the Ru film confirm the presence of Mn at the Ru/SiO{sub 2} interface.

McCoy, A. P.; Casey, P.; Bogan, J.; Hughes, G. [School of Physical Sciences, Dublin City University, Dublin 9 (Ireland); Lozano, J. G.; Nellist, P. D. [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom)

2012-12-03T23:59:59.000Z

214

Molecular-scale, Three-dimensional Non-Platinum Group Metal Electrodes for Catalysis of Fuel Cell Reactions  

NLE Websites -- All DOE Office Websites (Extended Search)

Molecular-scale, Three-dimensional Non-Platinum Group Molecular-scale, Three-dimensional Non-Platinum Group Metal Electrodes for Catalysis of Fuel Cell Reactions John B. Kerr Lawrence Berkeley National Laboratory (LBNL) September 30, 2009 Team Members: Adam Weber, Rachel Segalman, Robert Kostecki, Jeff Reimer, John Arnold, Martin Head-Gordon (LBNL). Piotr Zelenay, James Boncella, Yu Seung Kim, Neil Henson, Jerzy Chlistunoff (LANL). Steve Hamrock, Radoslav Atanasoski (3M) Budget: DOE share - $9.58MM over four years; 3M share - in-kind over four years. 2 Objectives 1) Demonstrate that non-platinum group metal catalysts can be used for oxygen reduction in polymer-coated electrode structures based on polyelectrolyte membranes. 2) Incorporate catalysts into polymer binders of composite electrodes for the construction of MEAs to demonstrate that this

215

Boron-nitrogen-hydrogen (BNH) compounds: recent developments in hydrogen storage, applications in hydrogenation and catalysis, and new syntheses  

Science Conference Proceedings (OSTI)

The strong efforts devoted to the exploration of BNH compounds for hydrogen storage have led to impressive advances in the field of boron chemistry. This review summarizes progress in this field from three aspects. It starts with the most recent developments in using BNH compounds for hydrogen storage, covering NH3BH3, B3H8¯ containing compounds, and CBN compounds. The following section then highlights interesting applications of BNH compounds in hydrogenation and catalysis. The last part is focused on breakthroughs in the syntheses and discovery of new BNH organic analogues. The role of N?H?+•••H?-?B dihydrogen interactions in molecule packing, thermal hydrogen evolution, and syntheses is also discussed within the review. Part of this research is supported by the U.S. Department of Energy’s Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences. Pacific Northwest National Laboratory is operated by Battelle.

Huang, Zhenguo; Autrey, Thomas

2012-11-15T23:59:59.000Z

216

Catalysis Center for Energy Innovation (CCEI): YouTube Channel for this Energy Frontier Research Center (EFRC)  

DOE Data Explorer (OSTI)

CCEI is among the 46 Energy Frontier Research Centers (EFRCs) funded by DOE and was established in the spring of 2009. CCEI is one of the very few externally funded centers on heterogeneous catalysis. CCEI leverages federal funding to enable technology transfer and commercialization through an industrial consortium. The center builds upon the long tradition of the Center for Catalytic Science and Technology (CCST) at the University of Delaware and extends its expertise within a virtual center among multiple partner institutions and national labs (University of Pennsylvania, Caltech, University of Minnesota, University of Massachusetts, Lehigh University, Brookhaven National Labs, University of North Carolina, and University of Southern California). CCEI provides an integrated approach to solving scientific and engineering problems that span across scales and disciplines, ranging from synthesis and characterization of novel catalysts to development and application of a multiscale modeling toolbox to reaction and reactor evaluation to technology transfer.[Copied with editing from http://www.youtube.com/catalysiscenter#p/u

217

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

DOE Green Energy (OSTI)

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.

Behrens, Malte

2012-03-28T23:59:59.000Z

218

New Family of Tiny Crystals Glow Bright in LED Lights | Advanced Photon  

NLE Websites -- All DOE Office Websites (Extended Search)

How Serotonin Receptors Can Shape Drug Effects, from LSD to Migraine How Serotonin Receptors Can Shape Drug Effects, from LSD to Migraine Medication X-rays Paint a Picture of Picasso's Pigments Antibody Evolution Could Guide HIV Vaccine Development Blue Ruthenium Dimer Catalysis for Hydrogen Generation A High-Pressure Nano-imaging Breakthrough Science Highlights Archives: 2013 | 2012 | 2011 | 2010 2009 | 2008 | 2007 | 2006 2005 | 2004 | 2003 | 2002 2001 | 2000 | 1998 | Subscribe to APS Science Highlights rss feed New Family of Tiny Crystals Glow Bright in LED Lights JUNE 7, 2013 Bookmark and Share Laue microdiffraction pattern acquired from a nanoribbon in experiments at the APS. Minuscule crystals that glow different colors may be the missing ingredient for white light-emitting diode (LED) lighting that illuminates homes and

219

A van der Waals density functional mapping of attraction in DNA dimers  

E-Print Network (OSTI)

The dispersion interaction between a pair of parallel DNA double-helix structures is investigated by means of the van der Waals density functional (vdW-DF) method. Each double-helix structure consists of an infinite repetition of one B-DNA coil with 10 base pairs. This parameter-free density functional theory (DFT) study illustrates the initial step in a proposed vdW-DF computational strategy for large biomolecular problems. The strategy is to first perform a survey of interaction geometries, based on the evaluation of the van der Waals (vdW) attraction, and then limit the evaluation of the remaining DFT parts (specifically the expensive study of the kinetic-energy repulsion) to the thus identified interesting geometries. Possibilities for accelerating this second step is detailed in a separate study. For the B-DNA dimer, the variation in van der Waals attraction is explored at relatively short distances (although beyond the region of density overlap) for a 360 degrees rotation. This study highlights the role...

Londero, Elisa; Schroder, Elsebeth

2013-01-01T23:59:59.000Z

220

Spectroscopic signatures of proton transfer dynamics in the water dimer cation  

SciTech Connect

Using full dimensional EOM-IP-CCSD/aug-cc-pVTZ potential energy surfaces, the photoelectron spectrum, vibrational structure, and ionization dynamics of the water dimer radical cation, (H2O)+2, were computed. We also report an experimental photoelectron spectrum which is derived from photoionization efficiency measurements and compares favorably with the theoretical spectrum. The vibrational structure is also compared with the recent experimental work of Gardenier et al. [J. Phys. Chem. A 113, 4772 (2009)] and the recent theoretical calculations by Cheng et al. [J. Phys. Chem. A 113 13779 (2009)]. A reduced dimensionality nuclear Hamiltonian was used to compute the ionization dynamics for both the ground state and first excited state of the cation. The dynamics show markedly different behavior and spectroscopic signatures depending on which state of the cation is accessed by the ionization. Ionization to the ground-state cation surface induces a hydrogen transfer which is complete within 50 femtoseconds, whereas ionization to the first excited state results in a much slower process.

Kamarchik, Eugene; Kostko, Oleg; Bowman, Joel M.; Ahmed, Musahid; Krylov, Anna I.

2009-12-21T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Deep Frying: Chemistry, Nutrition and Practical ApplicationsChapter 6 Formation and Analysis of Oxidized Monomeric, Dimeric, and Higher Oligomeric Triglycerides  

Science Conference Proceedings (OSTI)

Deep Frying: Chemistry, Nutrition and Practical Applications Chapter 6 Formation and Analysis of Oxidized Monomeric, Dimeric, and Higher Oligomeric Triglycerides Food Science Health Nutrition Biochemistry eChapters Food Science & Techn

222

An aspartate and a water molecule mediate efficient acid-base catalysis in a tailored antibody pocket  

DOE Green Energy (OSTI)

Design of catalysts featuring multiple functional groups is a desirable, yet formidable goal. Antibody 13G5, which accelerates the cleavage of unactivated benzisoxazoles, is one of few artificial enzymes that harness an acid and a base to achieve efficient proton transfer. X-ray structures of the Fab-hapten complexes of wild-type 13G5 and active-site variants now afford detailed insights into its mechanism. The parent antibody preorganizes Asp{sup H35} and Glu{sup L34} to abstract a proton from substrate and to orient a water molecule for leaving group stabilization, respectively. Remodeling the environment of the hydrogen bond donor with a compensatory network of ordered waters, as seen in the Glu{sup L34} to alanine mutant, leads to an impressive 10{sup 9}-fold rate acceleration over the nonenzymatic reaction with acetate, illustrating the utility of buried water molecules in bifunctional catalysis. Generalization of these design principles may aid in creation of catalysts for other important chemical transformations.

Debler, Erik W.; Müller, Roger; Hilvert, Donald; Wilson, Ian A.; (Scripps); (ETH Zurich)

2009-12-01T23:59:59.000Z

223

XIAP Induces NF-kB Activation via the BIR1/TAB1 Interaction and BIR1 Dimerization  

Science Conference Proceedings (OSTI)

In addition to caspase inhibition, X-linked inhibitor of apoptosis (XIAP) induces NF-{kappa}B and MAP kinase activation during TGF-b and BMP receptor signaling and upon overexpression. Here we show that the BIR1 domain of XIAP, which has no previously ascribed function, directly interacts with TAB1 to induce NF-{kappa}B activation. TAB1 is an upstream adaptor for the activation of the kinase TAK1, which in turn couples to the NF-{kappa}B pathway. We report the crystal structures of BIR1, TAB1, and the BIR1/TAB1 complex. The BIR1/TAB1 structure reveals a striking butterfly-shaped dimer and the detailed interaction between BIR1 and TAB1. Structure-based mutagenesis and knockdown of TAB1 show unambiguously that the BIR1/TAB1 interaction is crucial for XIAP-induced TAK1 and NF-{kappa}B activation. We show that although not interacting with BIR1, Smac, the antagonist for caspase inhibition by XIAP, also inhibits the XIAP/TAB1 interaction. Disruption of BIR1 dimerization abolishes XIAP-mediated NF-{kappa}B activation, implicating a proximity-induced mechanism for TAK1 activation.

Lu,M.; Lin, S.; Huang, Y.; Kang, Y.; Rich, R.; Lo, Y.; Myszka, D.; Han, J.; Wu, H.

2007-01-01T23:59:59.000Z

224

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

DOE Green Energy (OSTI)

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.

Akio Ishikawa; Manuel Ojeda; Enrique Iglesia

2005-03-31T23:59:59.000Z

225

Detailed mapping of the local Ir{sup 4+} dimers through the metal-insulator transitions of CuIr{sub 2}S{sub 4} thiospinel by x-ray atomic pair distribution function measurements.  

SciTech Connect

The evolution of the short-range structural signature of the Ir{sup 4+} dimer state in CuIr{sub 2}S{sub 4} thiospinel has been studied across the metal-insulator phase transitions as the metallic state is induced by temperature, Cr doping, and x-ray fluence. An atomic pair distribution function (PDF) approach reveals that there are no local dimers that survive into the metallic phase when this is invoked by temperature and doping. The PDF shows Ir{sup 4+} dimers when they exist, regardless of whether or not they are long-range ordered. At 100 K, exposure to a 98 keV x-ray beam melts the long-range dimer order within a few seconds, though the local dimers remain intact. This shows that the metallic state accessed on warming and doping is qualitatively different from the state obtained under x-ray irradiation.

Bozin, E. S.; Masadeh, A. S.; Hor, Y. S.; Mitchell, J. F.; Billinge, S. J. L.; Materials Science Division; BNL; Michigan State Univ.; Univ. of Jordan; Columbia Univ.

2011-01-24T23:59:59.000Z

226

Catalysis and Reactivity  

NLE Websites -- All DOE Office Websites (Extended Search)

understanding of basic principles of surface reactivity and its control by surface modification, on identification of active sites and full characterization of their electronic...

227

ZEOLITE CATALYSIS - TECHNOLOGY  

E-Print Network (OSTI)

p. 101 11. Ward, J. W, Oil I Hansford, R. D. , Reichle, A.A. B. and Weisz, P. B. , Oil and Gas J. Literature 15.F. E. and Smith, R. B. , Oil & Gas J. 1978, 76, May 22, 81

Heinemann, Heinz

2013-01-01T23:59:59.000Z

228

CATALYSIS SCIENCE AND TECHNOLOGY  

Science Conference Proceedings (OSTI)

This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Our objectives were to develop a multidisciplinary team and capabilities to develop a fundamental understanding of homogeneous, heterogeneous, and heterogenized catalysts. With the aid of theoretical chemistry approaches we explored and characterized the chemical reactivity and physical properties of a large number of catalytic systems.

M. ABRAMS; R. BAKER; ET AL

2000-08-01T23:59:59.000Z

229

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

synthesis gas by coal gasification is very expensive andin the cost of coal gasification would have a significantas K co , to promote gasification would be beneficial s1nce

Authors, Various

2011-01-01T23:59:59.000Z

230

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

costs for the production of SNG or Fischer-Tropsch productsof substitute natural gas (SNG) are highly susceptible to

Authors, Various

2011-01-01T23:59:59.000Z

231

HETEROGENEOUS CATALYSIS RESEARCH MEETING  

E-Print Network (OSTI)

production of SNG or Fischer-Tropsch products Therefore, abe trying to obtain from Fischer-Tropsch synthesis? Answer:intermediates in Fischer-Tropsch synthesis? Answer: It was

Authors, Various

2011-01-01T23:59:59.000Z

232

Catalysis in biomass gasification  

DOE Green Energy (OSTI)

The objective of these studies is to evaluate the technical and economic feasibility of producing specific gas products by catalytic gasification of biomass. Catalyst performance is a key factor in the feasibility of catalytic gasification processes. The results of studies designed to gain a fundamental understanding of catalytic mechanisms and causes of deactivation, and discussion of the state-of-the-art of related catalytic processes are presented. Experiments with primary and secondary catalysts were conducted in a 5-cm-diameter, continuous-wood-feed, fixed-catalyst-bed reactor. The primary catalysts used in the experiments were alkali carbonates mixed with the biomass feed; the secondary catalysts included nickel or other transition metals on supports such as alumina, silica, or silica-alumina. The primary catalysts were found to influence wood pyrolysis as well as the char/steam reaction. Secondary catalysts were used in a fixed-bed configuration to direct gas phase reactions. Results of the performance of these catalysts are presented. Secondary catalysts were found to be highly effective for conversion of biomass to specific gas products: synthesis gases and methane-rich gas. With an active catalyst, equilibrium gas composition are obtained, and all liquid pyrolysis products are converted to gases. The major cause of catalyst deactivation was carbon deposition, or coking. Loss of surface area by sintering was also inportant. Catalyst deactivation by sulfur poisoning was observed when bagasse was used as the feedstock for catalytic gasification. Mechanisms of catalyst activity and deactivation are discussed. Model compounds (methane, ethylene, and phenol) were used to determine coking behavior of catalysts. Carbon deposition is more prevalent with ethylene and phenol than with methane. Catalyst formulations that are resistant to carbon deposition are presented. 60 references, 10 figures, 21 tables.

Baker, E.G.; Mudge, L.K.

1984-06-01T23:59:59.000Z

233

Energy and Catalysis  

Science Conference Proceedings (OSTI)

Mar 13, 2012 ... Third Generation PV encompasses a wide diversity of materials and ... More Efficient Polymer Solar Cells by Doping with Ferroelectric Dipoles: ...

234

ZEOLITE CATALYSIS - TECHNOLOGY  

E-Print Network (OSTI)

and Weisz, P. B. , Oil and Gas J. Literature 15. Heinemann,Edinburgh 7. Oblad, A. G. Oil and Gas J. 1972, 70, (13), 84F. E. and Smith, R. B. , Oil & Gas J. 1978, 76, May 22, 81

Heinemann, Heinz

2013-01-01T23:59:59.000Z

235

Catalysis Without Precious Metals  

Science Conference Proceedings (OSTI)

Written for chemists in industry and academia, this ready reference and handbook summarizes recent progress in the development of new catalysts that do not require precious metals. The research thus presented points the way to how new catalysts may ultimately supplant the use of precious metals in some types of reactions, while highlighting the remaining challenges. This material is based upon work 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.

Bullock, R. Morris

2010-11-01T23:59:59.000Z

236

ZEOLITE CATALYSIS - TECHNOLOGY  

E-Print Network (OSTI)

Rheume, eta/. XBL 805-1065 FIGURE 3 l •--Catalytic reforminga--Catalytic reforming+ selectoforming Q) E Q) +w u 70

Heinemann, Heinz

2013-01-01T23:59:59.000Z

237

Neutrons and Catalysis  

NLE Websites -- All DOE Office Websites (Extended Search)

include: Peter Stair, Northwestern University Eugene Mamontov, ORNL Jeroen A. van Bokhoven, ETH Zurich David Sholl, Georgia Tech Robert Blankenship, Washington University A. J....

238

ZEOLITE CATALYSIS - TECHNOLOGY  

E-Print Network (OSTI)

+ Gasoline, Vol % Dry Gas Wt. Coke, Wt. % From: Eastwood etgasoline, with lower gas and coke yields, as well as number.bed catalyst. However, a residual coke level of 0.5-l.O% was

Heinemann, Heinz

2013-01-01T23:59:59.000Z

239

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

DOE Green Energy (OSTI)

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.

Akio Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

2007-03-31T23:59:59.000Z

240

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

DOE Green Energy (OSTI)

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

Rodriguez,J.A.; Liu, P.

2008-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Hydrogen and methane syntheses through radiation catalysis. Progress report, September 1, 1978-August 1, 1979. [/sup 60/Co radiolysis of water  

DOE Green Energy (OSTI)

Results of the second contract year are described on production of hydrogen through water radiolysis at /sup 60/Co gamma energies, in the presence of solid oxide catalysts. The intent of the research is an improved theoretical understanding of radiation-induced hydrogen generation within the framework of the electronic theory of catalysis. Correlation of hydrogen yield with catalytic activity, based on prior work, was difficult to attain and an assessment of experimental parameters was made. Three sets of observations appear of some significance, however: (1) Antimony oxide (Sb/sub 2/O/sub 3/, Eg = 3.3) shows consistently a dramatic increase in catalytic performance which cannot be attributed solely to band gap values. (2) There appears to be a correlation between hydrogen yield and dielectric properties of the catalyst. (3) Gamma irradiation changes the constitutive electrical properties of oxide catalyts in a manner proportional to hydrogen yields. Subsequent research will examine items 1, 2, and 3 more fully. It will also evaluate quantitatively the utility of the theoretical model.

None

1979-09-01T23:59:59.000Z

242

Facile Thermal W-W Bond Homolysis in the N-Heterocyclic Carbene-Containing Tungsten Dimer [CpW(CO)2(IMe)]2  

SciTech Connect

The thermal W-W bond homolysis in [CpW(CO)2(IMe)]2 (IMe = 1,3-dimethylimidazol-2-ylidene) was investigated and was found to occur to a large extent compared to other tungsten dimers such as [CpW(CO)3]2. CpW(CO)2(IMe)H was prepared by heating a solution of [IMeH]+[CpW(CO)2(PMe3)]?, and exists in solution as a mixture of interconverting cis and trans isomers. The carbene rotation in CpW(CO)2(IMe)H was explored by DFT calculations, and low enthalpic barriers (< 3.5 kcal mol?1) are predicted. CpW(CO)2(IMe)H has pKaMeCN = 31.5(3) and deprotonation with KH gives K+[CpW(CO)2(IMe)]? (• MeCN). Hydride abstraction from CpW(CO)2(IMe)H with Ph3C+PF6? in the presence of a coordinating ligand L (MeCN or THF) gives [CpW(CO)2(IMe)(L)]+PF6?. Electrochemical measurements on the anion [CpW(CO)2(IMe)]? in MeCN, together with digital simulations, give an E1/2 of ?1.54(2) V vs Cp2Fe+/0 for the [CpW(CO)2(IMe)]•/? couple. A thermochemical cycle provides the solution bond dissociation free energy of the W-H bond of CpW(CO)2(IMe)H as 61.3(6) kcal mol?1. In the electrochemical oxidation of [CpW(CO)2(IMe)]?, reversible dimerization of the electrogenerated radical CpW(CO)2(IMe)• occurs, and digital simulation provides kinetic and thermodynamic parameters for the monomer-dimer equilibrium: kdimerization ~ 2.5 ? 104 M?1 s?1, khomolysis ~ 0.5 s?1 (i.e., Kdim ~ 5 ? 104 M?1). Reduction of [CpW(CO)2(IMe)(MeCN)]+PF6? with cobaltocene gives the dimer [CpW(CO)2(IMe)]2, which in solution exists as a mixture of anti and gauche rotomers. As expected from the electrochemical experiments, the dimer is in equilibrium with detectable amounts of CpW(CO)2(IMe)•. This species was observed by IR spectroscopy, and its presence in solution is also in accordance with the observed reactivity toward 2,6-di-tert-butyl-1,4-benzoquinone, chloroform and dihydrogen. This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences and Geosciences. Pacific Northwest National Laboratory is a multiprogram national laboratory operated for DOE by Battelle. The EPR studies were performed at EMSL, a national scientific user facility sponsored by the Department of Energy’s Office of Biological and Environmental Research located at Pacific Northwest National Laboratory.

van der Eide, Edwin F.; Liu, Tianbiao L.; Camaioni, Donald M.; Walter, Eric D.; Bullock, R. Morris

2012-03-05T23:59:59.000Z

243

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

Science Conference Proceedings (OSTI)

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.

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

2012-02-08T23:59:59.000Z

244

Excited states of the bacteriochlorophyll b dimer of rhodopseudomonas viridis. A QM/MM study of the photosynthetic reaction center that includes MM polarization  

Science Conference Proceedings (OSTI)

We present a hybrid quantum mechanical/molecular mechanical (QM/MM) model for microscopic solvation effects that includes polarizability in the MM region (QM/MMpol). QM/MMpol treatment of both ground and excited states is presented in the formalism. We present QM/MMpol analysis of the ground and electronic excited states of the bacteriochlorophyll b dimer (P) of the photosynthetic reaction center (RC) of Rhodopseudomonas viridis using the INDO/S method. The static-charge potential from the MM model of the RC alone causes Q{sub y1} to have significantly better agreement with the Stark effect results than isolated P. However, consideration of the protein polarization potential is further required to obtain more complete agreement with Stark effect experiments. Thus, we calculate a Q{sub y1} transition energy at 10826 cm{sup -1} with a ground to excited state change in dipole moment of 4.8 D; an absorption Stark effect angle of 43{degree}; a net shift of 0.15 electrons from the L subunit to the M subunit of P; and a linear dichroism angle (between the transition moment of Q{sub y1} and the pseudo-C{sub 2} axis of the RC) of 81{degree}. These results are in good agreement with experiment. Interestingly, we find that net CT increase is greater for Q{sub y1} than for the second excited state of P (Q{sub y2}), a result that we anticipated in an early model dimer study. 77 refs., 3 figs., 2 tabs.

Thompson, M.A.; Schenter, G.K. [Pacific Northwest Lab., Richland, WA (United States)

1995-04-27T23:59:59.000Z

245

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

DOE Green Energy (OSTI)

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

U. Burghaus

2012-07-05T23:59:59.000Z

246

SOUTHWEST CATALYSIS 2012 SPRING SYMPOSIUM  

E-Print Network (OSTI)

, and hydrogen are activated with energetic sources such as microwaves to generate plasmas, direct current (DC include the hot filament [2] and many types of microwave plasma [3], which typically have *Corresponding is expected to be negligible since the diamond phase of carbon is very stable and gasification of dia- mond

247

Energy and Catalysis Technologies I  

Science Conference Proceedings (OSTI)

Mar 1, 2011 ... Polymer based photovoltaic (PV) technology is an exciting solar-electric conversion paradigm due to high extinction coefficient of polymers and ...

248

"Nanocrystal bilayer for tandem catalysis"  

E-Print Network (OSTI)

Part VI. Hydrogenolysis of Ethane, Propane, n-Butane andiso-Butane over Supported Platinum Catalysts. J. Catal. 176,

Yamada, Yusuke

2012-01-01T23:59:59.000Z

249

Palladium Catalysis for Energy Applications  

DOE Green Energy (OSTI)

Palladium (Pd) is an attractive catalyst for a range of new combustion applications comprising primary new technologies for future industrial energy needs, including gas turbine catalytic combustion, auto exhaust catalysts, heating and fuel cells. Pd poses particular challenges because it changes both chemical state and morphology as a function of temperature and reactant environment and those changes result in positive and negative changes in activity. Interactions with the support, additives, water, and contaminants as well as carbon formation have also been observed to affect Pd catalyst performance. This report describes the results of a 3.5 year project that resolves some of the conflicting reports in the literature about the performance of Pd-based catalysts.

Pfefferle, L. D.; Datye, A.

2001-03-01T23:59:59.000Z

250

Energy Materials: Storage, Generation, Catalysis  

Science Conference Proceedings (OSTI)

Mar 1, 2011 ... Of the many possible battery chemistries, the so-called “Li-air” system is noteworthy in that its theoretical capacity (~5 kWh/kg, including mass of ...

251

Effect of nonexcitonic interactions among the paired molecules on the Q sub y transition of bacteriochlorophyll dimers. Applications to the primary electron donors P-860 and P-960 in bacterial reaction centers  

Science Conference Proceedings (OSTI)

X-ray diffraction of reaction centers (RCs) from two strains of purple bacteria, Rhodobacter sphaeroides and Rhodopseudomonas viridis, revealed that their primary electron donors, P-860 and P-960, are tight dimers of bacteriochlorophyll (Bchl) a and b, respectively. The geometry of the paired molecules is such that their transition monopoles strongly interact, resulting in a bathochromic shift of the Q{sub y} bands. Recent calculations based upon interactions among point-charge monopoles (PCM) showed that exciton coupling among the localized Q{sub y} transitions of the paired molecules can account for part of the shift. The origin of the remaining nonexcitonic shift is controversial. In this communication the authors show that there is a ratio of 1.2-1.5 between the nonexcitonic shift and the exciton splitting of the Q{sub y} transition in several Bchl dimers in vitro.

Rosenbach-Belkin, V.; Fisher, J.R.E.; Scherz, A. (Weizmann Inst. of Science, Rehovot (Israel))

1991-01-16T23:59:59.000Z

252

The Importance of the Strictly Conserved, C-terminal Glycine Residue in Phosphoenolpyruvate Carboxylase for Overall Catalysis: Mutagenesis and Truncation of GLY-961 in the Sorghum C4 Leaf Isoform  

Science Conference Proceedings (OSTI)

Phosphoenolpyruvate carboxylase (PEPC) is a 'multifaceted', allosteric enzyme involved in C4 acid metabolism in green plants/microalgae and prokaryotes. Before the elucidation of the three-dimensional structures of maize C4 leaf and Escherichia coli PEPC, our truncation analysis of the sorghum C4 homologue revealed important roles for the enzyme's C-terminal {alpha}-helix and its appended QNTG{sup 961} tetrapeptide in polypeptide stability and overall catalysis, respectively. Collectively, these functional and structural observations implicate the importance of the PEPC C-terminal tetrapeptide for both catalysis and negative allosteric regulation. We have now more finely dissected this element of PEPC structure-function by modification of the absolutely conserved C-terminal glycine of the sorghum C4 isoform by site-specific mutagenesis (G961(A/V/D)) and truncation ({Delta}C1/C4). Although the C4 polypeptide failed to accumulate in a PEPC{sup -} strain (XH11) of E. coli transformed with the Asp mutant, the other variants were produced at wild-type levels. Although neither of these four mutants displayed an apparent destabilization of the purified PEPC homotetramer, all were compromised catalytically in vivo and in vitro. Functional complementation of XH11 cells under selective growth conditions was restricted progressively by the Ala, {Delta}C1 and Val, and {Delta}C4 modifications. Likewise, steady-state kinetic analysis of the purified mutant enzymes revealed corresponding negative trends in k{sub cat} and k{sub cat}/K0.5 (phosphoenolpyruvate) but not in K{sub 0.5} or the Hill coefficient. Homology modeling of these sorghum C-terminal variants against the structure of the closely related maize C4 isoform predicted perturbations in active-site molecular cavities and/or ion-pairing with essential, invariant Arg-638. These collective observations reveal that even a modest, neutral alteration of the PEPC C-terminal hydrogen atom side chain is detrimental to enzyme function.

Xu,W.; Ahmed, S.; Moriyama, H.; Chollet, R.

2006-01-01T23:59:59.000Z

253

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  

Science Conference Proceedings (OSTI)

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.

Ferguson, Michael James

2005-12-15T23:59:59.000Z

254

cis-Bis(bipyridine)ruthenium Imidazole Derivatives  

NLE Websites -- All DOE Office Websites (Extended Search)

The importance of these molecules is associated with their frequent use in the modification of proteins at histidine residues and in comparisons of the modified protein...

255

Substituted Tetraammine Ruthenium Cytochrome c Derivatives  

NLE Websites -- All DOE Office Websites (Extended Search)

Myung-ok P. Cho, and Stephan S. Isied Inorg. Chem. 34, 3301-3309 (1995) Abstract: Horse-heart (hh) cytochrome c, modified at His-33, and Candida krusei (Ck) cytochrome c, modified...

256

Ruthenium on Carbon Nanostructures for Supercapacitor ...  

Supercapacitors are electrical storage devices that can deliver a huge amount of energy in a short time. Such a surge of energy is important in hybrid electric and ...

257

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  

Science Conference Proceedings (OSTI)

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.

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

2012-10-23T23:59:59.000Z

258

Understanding enzyme catalysis using computer simulation  

SciTech Connect

Enzymes catalyze biochemical reactions with remarkable specificity and efficiency, usually under physiological conditions. Computer simulation is a powerful tool for understanding enzyme catalytic mechanisms, particularly in cases where standard experimental techniques may be of limited utility. Here, we present an overview of the application of computer simulation techniques to understanding enzyme catalytic mechanisms. Examples using quantum chemical methods, as well as combined quantum mechanical/classical mechanical approaches, are provided.

Parks, Jerry M [ORNL; Imhof, Petra [ORNL; Smith, Jeremy C [ORNL

2010-01-01T23:59:59.000Z

259

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

or heterogeneous (where the reactants and catalysts are in separate phases--normally gas or liquids over solids). Heterogeneous catalysts act in a different phase than the...

260

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

greater stability. In 1975 Exxon commercialized operationoil" mode (3500 cft/bbl). The "Exxon Dlonor Solvent" processco 2 particle pressure. In 1977, Exxon announced work on a

Heinemann, Heinz

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

R. and Stein, T. R. , . Rev. Oil Gas Journal, June 6, 1977.Logan, R. s. and Banks, R. L. Oil Gas Journal, 1968, 66(21),P. H. . Rev,, 1978, 18(1). Oil Gas Journal, 1963, 61(13),

Heinemann, Heinz

2013-01-01T23:59:59.000Z

262

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

cost of the product hydrogen. Development of models to conduct economic analysis of biogas clean-up in stationary fuel cells systems. Analysis of fuel cell based combined heat...

263

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

operate on reformate or syngas produced from various fuels that include natural gas, biogas, coal gas, etc. All of these fuels contain species that can potentially damage the...

264

Argonne Chemical Sciences & Engineering - People - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

Fuel Cell Engineering Shabbir Ahmed, Chemical Engineer and Group Leader phone: 630252-4553, fax: 630972-4553, ahmeds@anl.gov Ph.D., Chemical Engineering, University of Nebraska...

265

Method for producing catalysis from coal  

SciTech Connect

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.

Farcasiu, Malvina (Pittsburgh, PA); Derbyshire, Frank (Lexington, KY); Kaufman, Phillip B. (Library, PA); Jagtoyen, Marit (Lexington, KY)

1998-01-01T23:59:59.000Z

266

EMSL and Institute for Integrated Catalysis (IIC)  

NLE Websites -- All DOE Office Websites (Extended Search)

of Washington Abhaya Datye, University of New Mexico Graeme Henkelman, University of Texas Raul Lobo, University of Delaware William Schneider, University of Notre Dame Len...

267

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

Dealkylation Catalytic Coal Liquefaction and Gasification a)Liquefaction Gasification c) IX Methanation Heterogeneous~IQUEFACTION AND GASIFICATION a) Liquefaction Production of

Heinemann, Heinz

2013-01-01T23:59:59.000Z

268

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

in a solvent, and the Fischer-Tropsch process involving theWorld War II, and a Fischer-Tropsch plant was built in South50) Conventional iron-type Fischer-Tropsch catalysts are

Heinemann, Heinz

2013-01-01T23:59:59.000Z

269

Argonne Chemical Sciences & Engineering - Publications - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

72-86 G. Jacobs, A. Sarkar, B. H. Davis, D. Cronauer, A. J. Kropf, and C. L. Marshall, "Fischer-Tropsch Synthesis: Temperature Programmed EXAFSXANES Characterization of the...

270

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

Alternative Electrocatalysts Argonne's current research with electrocatalysts include: Non-Platinum Bimetallic Cathode Electrocatalysts for Polymer Electrolyte Fuel Cells...

271

Nanoscale Advances in Catalysis and Energy Applications  

E-Print Network (OSTI)

 Selectivity.   Angewandte  Chemie-­‐ International   Liquids.   Angewandte  Chemie-­‐International   clusters.   Angewandte  Chemie-­‐International  

Li, Yimin

2011-01-01T23:59:59.000Z

272

Catalysis using hydrous metal oxide ion exchangers  

DOE Patents (OSTI)

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.

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

1983-07-21T23:59:59.000Z

273

Catalysis using hydrous metal oxide ion exchanges  

DOE Patents (OSTI)

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.

Dosch, Robert G. (Albuquerque, NM); Stephens, Howard P. (Albuquerque, NM); Stohl, Frances V. (Albuquerque, NM)

1985-01-01T23:59:59.000Z

274

Science: Catalysis, Water Splitting Goes Au Naturel  

NLE Websites -- All DOE Office Websites (Extended Search)

J. Alper, "Water Splitting Goes Au Naturel", Science, 299, 1686-1687 (2003). A.K. Jones, E. Sillery, S.P.J. Albracht, and F.A. Armstrong, "Direct comparison of the electrocatalytic...

275

Hydrodesulfurization catalysis by Chevrel phase compounds  

DOE Patents (OSTI)

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.).

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

1985-12-24T23:59:59.000Z

276

Two component-three dimensional catalysis  

DOE Patents (OSTI)

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.

Schwartz, Michael (Boulder, CO); White, James H. (Boulder, CO); Sammells, Anthony F. (Boulder, CO)

2002-01-01T23:59:59.000Z

277

Toward computational screening in heterogeneous catalysis - TMS  

Science Conference Proceedings (OSTI)

Sep 11, 2007 ... This article describes the use of DFT calculations on multiple catalytic surfaces to obtain a specified "descriptor," a calculated value that can ...

278

Argonne Chemical Sciences & Engineering - People - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

cycle elucidation X-ray absorption spectroscopy of organometallic complexes SonBinh Nguyen, Chemist, Joint Appointment with Northwestern University e-mail: stn@anl.gov Aiwen...

279

Argonne Chemical Sciences and Engineering - Publications - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

3, 2010 M C. A. Mirkin, J. T. Hupp, R. Q. Snurr, L. J. Broadbelt, D. Tiede and S. T. Nguyen, "From Functional Supramolecular Chemistry to Metal-Organic Frameworks: Biomimetic...

280

Catalysis, CO2, Structural Materials and Polymers  

Science Conference Proceedings (OSTI)

... anthropogenic emissions from point sources such as coal-fired power plants. ... Here we report a simple and low-cost method of preparing carbon composite ...

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Collaborations @ Catalysis: Reactivity and Structure Group |...  

NLE Websites -- All DOE Office Websites (Extended Search)

Bremen) Hicham Idriss (SABIC-Kaust) Louis Piper (SUNY Binghamton) Peter Chupas (Argonne National Lab) Trudy Bolin (Argonne National Lab) Donna Chen (University of South Carolina)...

282

Argonne Chemical Sciences & Engineering - People - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

State University 25+ years of industrial research at BP Heterogeneous catalyst fundamentals Synthesis of supported metal catalysts Reaction kinetics and pathways Acid...

283

BERKELEY CATALYSIS CENTER Distinguished Lecture Series  

E-Print Network (OSTI)

. NOX reduction is achieved by reacting exhaust NOX with ammonia in the presence of an SCR catalyst grid where NOX reduction takes place. The exhaust gas continues up through the stack where. A diagram of UConn's combustion and NOX reduction processes is provided in Figure 1. Figure 1: Diagram

Iglesia, Enrique

284

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

there were supplies of n-butane which could be isomerized.as a catalytic liquid n~butane gas was passed; in the other,and ts: butadiene, 2) 1) butane lbenzene dehydro~~ genation

Heinemann, Heinz

2013-01-01T23:59:59.000Z

285

Argonne Chemical Sciences & Engineering - People - Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

Analytical Materials Chemistry, State University of New York at Binghamton Nanotechnology (nanomaterial synthesis and characterization) Fuel Cell Technology (catalyst...

286

Argonne Chemical Sciences & Engineering - Catalysis & Energy...  

NLE Websites -- All DOE Office Websites (Extended Search)

Solid Oxide Fuel Cells SOFC model In a SOFC, oxygen from air is reduced to ions at the cathode, which then diffuse through the electrolyte and oxidize the fuel (hydrogen) at the...

287

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

that were suspended in a molten salt heat exchanger, . F'catalyst containers in molten salt medium. Figure taken franwater. The copper salts are molten and sorbed in the alumina

Heinemann, Heinz

2013-01-01T23:59:59.000Z

288

Catalysis: Reactivity and Structure Group | Chemistry Department...  

NLE Websites -- All DOE Office Websites (Extended Search)

apply new approaches for the in-situ characterization of heterogeneous catalysts using facilities available at the National Synchrotron Light Source for X-ray diffraction, X-ray...

289

A BRIEF HISTORY OF INDUSTRIAL CATALYSIS  

E-Print Network (OSTI)

Naphtha Reforming Catalytic reforming of naphthas serves toalready apparent in catalytic reforming as outlined above,catalysts (e.g. , in catalytic reforming, methanatiom, or

Heinemann, Heinz

2013-01-01T23:59:59.000Z

290

Plasma-Catalysis During Temperature Transient Testing  

DOE Green Energy (OSTI)

A combination of catalysts is used together with nonthermal plasma in simulated diesel exhaust, while the gas temperature is varied. The catalysts both store and convert pollutants. As a result, pollutant concentrations during temperature ramps are different than those at steady state conditions. The data are presented for plasma followed by BaY, alumina, and Pt catalysts in simulated exhaust. When temperature ramps from high to low, apparent NOx conversion is quite high. However, when temperature is ramped from low to high, lower apparent conversions are seen. In a typical test cycle, average NOx conversion between 100 and 400 C is 60%. Peak conversion during the down ramp is over 90%, and minimum conversion during the up ramp is 30%. The composition of the effluent gas also varies during the temperature cycle. Intermediates such as methyl nitrate and hydrogen cyanide are not present following the combination of catalysts.

Hoard, John

2001-08-05T23:59:59.000Z

291

NIST Potential Energy Surfaces of Calcium Dimer ...  

Science Conference Proceedings (OSTI)

... B. Bussery-Honvault and R. Moszynski Molecular Physics 104, 2387 (2006). ... Phys. ... A theoretical investigation of the origins of the green and red ...

292

Effects of B{sub 18}H{sub x}{sup +} and B{sub 18}H{sub x} dimer ion implantations on crystallinity and retained B dose in silicon  

SciTech Connect

The effects of B{sub 18}H{sub x}{sup +} and B{sub 18}H{sub x} dimer ion (B{sub 36}H{sub y}{sup +}) implantations on Si crystallinity and the retained B dose in Si were investigated using B{sub 18}H{sub x} bombardment and compared with the effects of B{sup +} implantation. Crystallinity was estimated for the implantation dose using molecular dynamic simulations (MDSs) and was quantified using the optical thickness obtained from spectroscopic ellipsometry. The authors focused on the crystallinity at a low B dose and compared the amorphized zones predicted by MDS for B{sub 18}H{sub x}{sup +} implantation with those measured using transmission electron microscopy; the predicted and measured results were in reasonable agreement. The authors then used their understanding of B{sub 18}H{sub x} bombardment to discuss the process for the generation of larger amorphized zones and thicker amorphized layers, as observed in B{sub 36}H{sub y}{sup +} implantation. The retained B dose and the sputtering were examined with secondary ion mass spectroscopy, focusing on a comparison of the retained B and the sputtering of Si and SiO{sub 2} surfaces. The retained B dose was lower for B{sub 18}H{sub x}{sup +} and B{sub 36}H{sub y}{sup +} implantations, with and without surface SiO{sub 2}, than for B{sup +} implantation, although no sputtering was observed. The reduction of the retained B dose was more severe in the samples with SiO{sub 2}. The origin of the differences between Si and SiO{sub 2} surfaces was considered to be Si melting; this was predicted by the MDSs, and observed indirectly as flat B profiles in the Si region. To examine the effects of both crystallinity and retained B dose on the electrical characteristics, the sheet resistance (R{sub S}) was measured. The R{sub S} for B{sub 18}H{sub x}{sup +} implantation was lower than that for B{sup +} implantation at both B doses studied. Additionally, the B{sub 36}H{sub y}{sup +} implantation under conditions that produced a thicker amorphized layer led to lower R{sub S} than B{sub 18}H{sub x}{sup +} implantation. These results indicate that both the amorphized layer and the amorphized zone contribute to the activation of more B atoms.

Kawasaki, Yoji; Shibahara, Kentaro [Renesas Electronics Corporation, 751 Horiguchi, Hitachinaka, Ibaraki 312-8504 (Japan) and Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8530 (Japan); Research Institute for Nanodevice and Bio Systems, Hiroshima University, 1-4-2 Kagamiyama, Higashihiroshima, Hiroshima 739-8527 (Japan) and Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8530 (Japan)

2012-01-15T23:59:59.000Z

293

Intermolecular ET between Ruthenium Complexes and Cytochrome c  

NLE Websites -- All DOE Office Websites (Extended Search)

Comparative Kinetic Analysis of Reversible Intermolecular Electron-Transfer Comparative Kinetic Analysis of Reversible Intermolecular Electron-Transfer Reactions between a Series of Pentaammineruthenium Complexes and Cytochrome c Martin Meier, Ji Sun, James F. Wishart, and Rudi van Eldik Inorg. Chem. 35, 1564-1570 (1996) [Find paper at ACS Publications] Abstract: In this kinetic and thermodynamic study, the reversible outer-sphere electron-transfer reactions between a series of Ru(NH3)5L3+/2+ complexes (L = etpy, py, lut) (etpy = 4-ethylpyridine; py = pyridine; lut = 3,5-lutidine) and cytochrome c were investigated as a function of ionic strength, buffer, pH, temperature, and pressure. Due to the low driving forces of these systems, it was possible to study all the reactions in both redox directions. The observed rate constants for various L are correlated

294

New Phases in Ruthenium-Containing Single-Crystal Superalloys  

Science Conference Proceedings (OSTI)

in the performance and efficiency of aircraft and power generation turbines. To design alloys with long term microstructural stability at high temperatures requires ...

295

Evaluation of Ruthenium-Bearing Single Crystal Superalloys - A ...  

Science Conference Proceedings (OSTI)

High fuel costs and increasing environmental pressures demand unprecedented and ambitious .... maximum of 200 cycles. The initial weight and dimensions of ...

296

Atomic Partitioning of Ruthenium in Ni-Based Superalloys  

Science Conference Proceedings (OSTI)

A twin-jet polisher along with a solution of. 10 vol% perchloric acid in ethanol at approximately -5°C was used for this latter stage. To perform statistical ALCHEMI  ...

297

Effect of Ruthenium on Microstructure and Stress Rupture Properties ...  

Science Conference Proceedings (OSTI)

which is the usual content in third generation single crystal alloys to 4?5 wt. ..... coefficient to characterize the distribution behavior of the alloying elements ...

298

Molecular water oxidation catalyst  

DOE Patents (OSTI)

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.

Gratzel, Michael (St. Sulpice, CH); Munavalli, Shekhar (Bel Air, MD); Pern, Fu-Jann (Lakewood, CO); Frank, Arthur J. (Lakewood, CO)

1993-01-01T23:59:59.000Z

299

AutoDimer: a screening tool for primer-dimer and hairpin ...  

Science Conference Proceedings (OSTI)

... A sample sequence input file and installation assistance is pro- vided for the ... 33.Hall, TS, P. Pancoska, PV Riccelli, K. Man- dell, and AS Benight. ...

2004-09-08T23:59:59.000Z

300

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Degradation Degradation One of the primary challenges facing the development of polymer electrolyte fuel cells (PEFCs) for automotive and stationary power applications is the durability of the fuel cell materials. Though significant progress has been made toward achieving the technical target of 5,000 operating hours, the current reported durability status for conventional stacks is considerably shorter (~2,000 hours). Typical degradation rates for constant load conditions are 25-40 µ and can be an order of magnitude higher when operating under non-steady-state conditions prevalent in the automotive application, including load and start-stop cycling and extended time at open circuit. The observed degradation under these conditions has reversible and irreversible components with one of the most dominant contributors to irreversible degradation being loss of cathode oxygen reduction activity.

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Catalytic Removal of Oxides of Nitrogen from Diesel Exhaust Streams Catalytic Removal of Oxides of Nitrogen from Diesel Exhaust Streams Nox removal One of the planet's major pollutants, nitrogen oxides (NOx) are formed in all high temperature fuel-air flames, and so they are a particular emissions problem for diesel engines. Although diesel-fueled engines emit very small amounts of carbon monoxide (CO) and hydrocarbons (HCs), they do, however, release relatively high amounts of NOx and particulate matter (PM) or soot--the emissions that lead to acid rain, smog, and poor health conditions. Thus, removing NOx from emission streams has become a global concern. Argonne researchers have developed an innovative diesel DeNOx catalyst technology that provides industry with a totally passive, easy-to-use system for removing NOx from exhaust streams. Vehicle drivers do not need

302

2004 Catalysis Gordon Conference-June 27-July 2,  

Science Conference Proceedings (OSTI)

The Conference was well-attended with 100 participants (attendees list included). The attendees represented the spectrum of endeavor in this field coming from academia, industry, and government laboratories, U.S. and foreign scientists, senior researchers, young investigators, and students. In designing the formal speakers program, emphasis was placed on current unpublished research and discussion of the future target areas in this field. There was a conscious effort to stimulate lively discussion about the key issues in the field today. Time for formal presentations was limited in the interest of group discussions. In order that more scientists could communicate their most recent results, poster presentation time was scheduled. The formal schedule and speaker program and the poster program is given. In addition to these formal interactions, 'free time' was scheduled to allow informal discussions. Such discussions are fostering new collaborations and joint efforts in the field.

Nancy Ryan Gray Peter C. Stair

2005-08-17T23:59:59.000Z

303

Partnering at the National Laboratories: Catalysis as a Case Study  

Science Conference Proceedings (OSTI)

The role of the national laboratories, particularly the defense program laboratories, since the end of the cold war, has been a topic of continuing debate. The relationship of national laboratories to industry spurred debate which ranged from designating the labs as instrumental to maintaining U.S. economic competitiveness to concern over the perception of corporate welfare to questions regarding the industrial globalization and the possibility of U.S. taxpayer dollars supporting foreign entities. Less debated, but equally important, has been the national laboratories' potential competition with academia for federal research dollars and discussions detailing the role of each in the national research enterprise.

JACKSON,NANCY B.

1999-09-14T23:59:59.000Z

304

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen Storage Hydrogen Storage Hydrogen Storage Scott Kirklin, a co-op student researcher, closely examines a polymer sample before characterizing its surface structure. The capacity of on-board hydrogen storage is critical to the development of hydrogen-powered fuel cell vehicles. To be practical, the 2010 performance targets of the hydrogen storage system set by the U.S. Department of Energy (DOE) include a gravimetric capacity of at least 0.06 kg H2/kg and a volumetric capacity of 0.045 kg H2/L at ambient temperature. Furthermore, the adsorbent cost must be less than $4/kWh. These requirements pose significant challenges to the storage material development. Argonne, in collaboration with the University of Chicago (U of C), is addressing these challenges by exploring a new class of hydrogen adsorbent,

305

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

Production of Hydrogen using Copper-Chlorine Cycle Production of Hydrogen using Copper-Chlorine Cycle In view of the upcoming hydrogen economy, Argonne researchers are studying thermochemical cycles to determine their potential to produce hydrogen effectively with respect to energy usage and cost. Most emphasis has been placed on baseline sulfur cycles, though a small effort is currently ongoing for alternative cycles, one of which is the copper chloride (Cu-Cl) cycle. The chemistry of this cycle is illustrated in the figure below. Heat/electricity and water are the only inputs, while oxygen and hydrogen are the only products. All of the chemicals are recycled. Production of hydrogen using copper-chlorine cycle diagram The Copper Chloride Cycle Researcher Magali Ferrandon sets up a copper-chloride cycle experiment

306

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

High-Temperature Steam Electrolysis High-Temperature Steam Electrolysis High-temperature steam electrolysis (HTSE) can be used to make hydrogen for use in automotive fuel cells or other portable applications. HTSE takes advantage of solid oxide fuel cell (SOFC) technology to split steam into hydrogen and oxygen at high temperatures. This process can use the waste heat from high-temperature industrial processes to lower the need for electrical energy to split water, which gives it an advantage over conventional water electrolysis. Also, unlike steam methane reforming, the current state-of-the-art method for making hydrogen, HTSE does not release any greenhouse gases. As part of the Nuclear Hydrogen Initiative, Argonne has conducted studies of the causes of HTSE component degradation over extended operation time periods. We have developed methods for determining areas where degradation has occurred using X-ray fluorescence mapping, and X-ray Absorption Near Edge Structure (XANES) spectroscopic techniques at the Advanced Photon Source (APS). APS results were complimented by electron microscopy and energy dispersive spectroscopy, as shown in the figure.

307

Argonne Chemical Sciences & Engineering - Publications - Catalysis and  

NLE Websites -- All DOE Office Websites (Extended Search)

Ceramic Electrochemistry Ceramic Electrochemistry A A.Akkoyunlu, R. Koc, J. Mawdsley and J. D. Carter, "Synthesis of Submicron-Size CaB6 Powders Using Various Boron Sources," 35th International Conference and Exposition on Advanced Ceramics and Composites (ICACC'11), Daytona Beach, FL, January 23-28, 2011 B A. B. Bose, R. Shaik, and J. Mawdsley, "Optimization of the Performance of Polymer Electrolyte Fuel Cell Membrane-Electrode Assemblies: Roles of Curing Parameters on the Catalyst and Ionomer Structures and Morphology," Journal of Power Sources 182(1), 61-65 (2008) C J. D. Carter, "Status of Fuel Cell Technologies,"Electric Apparatus Service Association, Willowbrook, IL, September 13, 2011 (viewgraph presentation) J. D. Carter, "Manufacturing Fuel Cell Manhattan Project: Ceramic Fuel Cells (SOFC)," DOE H2/FC Manufacturing R&D Workshop, Washington, DC, August 11, 2011

308

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

Durability Durability One of the primary challenges facing the development of polymer electrolyte fuel cells (PEFCs) for automotive and stationary power applications is the durability of the fuel cell materials. Though significant progress has been made toward achieving the technical target of 5,000 operating hours, the current reported durability status for conventional stacks is considerably shorter (~2,000 hours). Typical degradation rates for constant load conditions are 25-40 µ and can be an order of magnitude higher when operating under non-steady-state conditions prevalent in the automotive application, including load and start-stop cycling and extended time at open circuit. The observed degradation under these conditions has reversible and irreversible components with one of the most dominant contributors to irreversible degradation being loss of cathode oxygen reduction activity.

309

Argonne Chemical Sciences & Engineering - Catalysis & Energy Conversion -  

NLE Websites -- All DOE Office Websites (Extended Search)

A simplified schematic showing the various alternatives and steps in the production and distribution of hydrogen A simplified schematic showing the various alternatives and steps in the production and distribution of hydrogen A simplified schematic showing the various alternatives and steps in the production and distribution of hydrogen. Hydrogen for Fuel Cells We work on the production of hydrogen for use with fuel cell systems. We have applied our knowledge of fuel cell systems, their constraints, and infrastructure needs to our research in the field. Our research projects include: Development of catalysts and reactors using autothermal reforming of alcohols and hydrocarbon fuels for on-board fuel cell systems. Reforming of infrastructure fuels (natural gas, liquefied petroleum gas, ethanol, gasoline, and diesel). Integration of fuel processor components (reformer, shift reactor,

310

Argonne Chemical Sciences & Engineering - People - Catalysis and Energy  

NLE Websites -- All DOE Office Websites (Extended Search)

Electrochemical Projects Support Electrochemical Projects Support Walter F. Podolski, Chemical Engineer and Group Leader phone: 630/252-7558, fax: 630/972-4430, podolski@anl.gov Ph.D., Chemical Engineering, Northwestern University Technical contract management and support of research, development, and demonstration of fuel-cell-powered vehicles Thomas G. Benjamin, Chemical Engineer phone: 630/252-1632, fax: 630/252-4176, e-mail: benjamin@anl.gov BS, MS Chemical Engineering, University of Connecticut MBA University of Chicago Polymer electrolyte membrane fuel cells Hydrogen storage William L. Cleary, Mechanical Engineer, Project Manager phone: 202/506-1570 e-mail: bill.cleary@ee.DOE.gov John Kopasz, Inorganic Chemist phone : 630/252-7531, fax : 630/972-4405, e-mail: kopasz@anl.gov Ph.D., Inorganic Chemistry, State University of New York at Buffalo

311

Argonne Chemical Sciences & Engineering - Publications - Catalysis and  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen and Fuel Cell Materials Hydrogen and Fuel Cell Materials Summary Report, ANL-12/8, Natural Gas and Hydrogen Opportunities Workshop, Argonne National Laboratory, October 18-19, 2011 TM/N/C Cathode Catalyst for in Li-Air Battery Application, 5th International Conference on Polymer Batteries and Fuel Cells (PBFC-5), Argonne, IL, August 1-5, 2011 (poster presentation) Transition Metal--Nitrogen--Carbon Composite as Cathode Catalyst for in Li-air Battery Application, 5th International Conference on Polymer Batteries and Fuel Cells (PBFC-5), Argonne, IL, August 1-5, 2011 (poster presentation) Fundamental Studies of Platinum Electrocatalyst Degradation, 5th International Conference on Polymer Batteries and Fuel Cells (PBFC-5), Argonne, IL, August 1-5, 2011 (poster presentation)

312

JOURNAL OF CATALYSIS 179, 431442 (1998) ARTICLE NO. CA982178  

E-Print Network (OSTI)

-Borja, and Enrique Iglesia2 Department of Chemical Engineering, University of California at Berkeley, and Materials address: Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609. 2 lines for PdO (at 2 = 33.7 , 54.8 ) were detected infreshcatalystswithhighPdloadings(>3wt%)aftertreat

Iglesia, Enrique

313

High pressure heterogeneous catalysis in a low pressure UHV environment  

SciTech Connect

The major thrust of our research is to carry out for the first time a heterogeneous catalytic reaction that normally is observed only at high pressures (>1 atm) of reactant gas at low pressures (<10{sup {minus}4} Torr) in an ultrahigh vacuum environment. The reaction we have chosen is the steam reforming of methane on a Ni(111) crystal.

Ceyer, S.T.

1990-01-01T23:59:59.000Z

314

Light-driven uncoupling of nitrogenase catalysis from ATP hydrolysis  

E-Print Network (OSTI)

77 Figure 4.1. Genes in the major nif cluster from A.plasmids from digested nif gene inserts. Figure 4.5. Two-82 The Nif Gene

Roth, Lauren E.

2012-01-01T23:59:59.000Z

315

FIRST BERKELEY CATALYSIS AND SURFACE SCIENCE CONFERENCE JULY 1980  

E-Print Network (OSTI)

Arco Chemical Company Ashland Oil, Inc. Celanese CorporationCarbide Corporation Union Oil Co. of California iii FIRSTboth distillates and lube oils; alkylation of benzene with

Authors, Various

2013-01-01T23:59:59.000Z

316

Biomimetic C-H Oxidation Catalysis in Aqueous Solution  

E-Print Network (OSTI)

precipitated as a brown/orange oil and was purified byfractions, pale-colored oil was sometimes obtained.Adding acetone to the oil allowed the collection of solid

Djernes, Katherine Elizabeth

2013-01-01T23:59:59.000Z

317

Interacting Frameworks in Catalysis KungKiu Lau \\Lambda  

E-Print Network (OSTI)

of Manchester Manchester M13 9PL, UK kung­kiu@cs.man.ac.uk Shaoying Liu y Dept. of Computer Science Hiroshima City University 151­5, Ozuka, Numata­cho,Asaminami­ku Hiroshima, 731­31, Japan liu@white.sel.cs.hiroshima of the existing (semi­ \\Lambda Sponsored by Hiroshima City University under Hiroshima City Uni­ versity Grant

Lau, Kung-Kiu

318

Frontiers in Catalysis Science and Engineering Materials Science  

E-Print Network (OSTI)

, it is imperative to develop new processes for effective use of energy and to develop sustainable and clean energy Professor, Department of Chemistry & Biochemistry Abstract Energy is not only the driver for improving energy carriers and for converting them into directly usable energy. Design and synthesis of controlled

319

The Catalysis of Nuclear Reactions by mu Mesons  

DOE Green Energy (OSTI)

In the course of a recent experiment involving the stopping of negative K mesons in a 10-inch liquid hydrogen bubble chamber, an interesting new reaction was observed to take place. The chamber is traversed by many more negative {mu} mesons than K mesons, so that in the last 75,000 photographs, approximately 2500 {mu}{sup -} decays at rest have been observed. In the same pictures, several hundred {pi}{sup -} mesons have been observed to disappear at rest, presumably by one of the ''Panofsky reactions''. For tracks longer than 10 cm, it is possible to distinguish a stopping {mu} meson from a stopping {pi} meson by comparing its curved path (in a field of 11,000 gauss) with that of a calculated template. In addition to the normal {pi}{sup -} and {mu}{sup -} stoppings, we have observed 15 cases in which what appears (from curvature measurement) to be a {mu}{sup -} meson comes to rest in the hydrogen, and then gives rise to a secondary negative particle of 1.7 cm range, which in turn decays by emitting an electron. (A 4.1-Mev {mu} meson from {pi} - {mu} decay has a range of 1.0 cm.) The energy spectrum of the electrons from these 15 secondary particles looks remarkably like that of the {mu} meson. There are four electrons in the energy range 50 to 55 Mev, and none higher; the other electrons have energies varying from 50 Mev to 13 Mev. The most convincing proof that the primary particle actually comes to rest, and does not--for example--have a large resonant cross section for scattering at a residual range of 1.7 cm, is the following: In five of the 15 special events, there is a large gap between the last bubble of the primary track and the first bubble of the secondary track. This gap is a real effect, and not merely a statistical fluctuation in the spacing of the bubbles, since in some cases the tracks form a letter X, and in another case the secondary track is parallel to the primary, but displaced transversely by about 1 mm at the end of the primary. These real gaps appear also (although perhaps less frequently) between some otherwise normal-looking {mu}{sup -} endings and the subsequent decay electron; they are thought to be the distance traveled by the small neutral mesic atom.

Alvarez, L.W.; Bradner, H.; Crawford Jr, F.S.; Crawford, J.A.; Falk-Vairant, P.; Good, M.L.; Gow, J.D.; Hosenfeld, A.R.; Solmitz, F.; Stevenson, M.L.; Ticho, H.K.; Tripp, H.D.

1956-12-10T23:59:59.000Z

320

Method for producing high surface area chromia materials for catalysis  

SciTech Connect

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.

Gash, Alexander E. (Brentwood, CA); Satcher, Joe (Patterson, CA); Tillotson, Thomas (Tracy, CA); Hrubesh, Lawrence (Pleasanton, CA); Simpson, Randall (Livermore, CA)

2007-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

FIRST BERKELEY CATALYSIS AND SURFACE SCIENCE CONFERENCE JULY 1980  

E-Print Network (OSTI)

as 1913. Then in 19Z6 Fischer and Tropsch published theirThe Technology of the Fischer-Tropsch Process vii Friday,in potentially modifying Fischer-Tropsch reactions is

Authors, Various

2013-01-01T23:59:59.000Z

322

TECHNOLOGY DEVELOPMENT FOR IRON FISCHER-TROPSCH CATALYSIS  

DOE Green Energy (OSTI)

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.

Burtron H. Davis

1998-04-01T23:59:59.000Z

323

Technology development for iron fischer-tropsch catalysis  

SciTech Connect

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 5 catalysts synthesized in this program for activity, selectivity and aging characteristics.

Davis, B.H.

1997-05-14T23:59:59.000Z

324

Technology development for iron fisher-tropsch catalysis  

SciTech Connect

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.

Davis, B.H.

1997-07-15T23:59:59.000Z

325

Synthesis of Donor Ligands and Their Applications in Catalysis  

E-Print Network (OSTI)

Bertrand, G. Angewandte Chemie International Edition 2005,Bertrand, G. Angewandte Chemie International Edition 2005,Bertrand, G. Angewandte Chemie International Edition 2008,

DeHope, Alan

2010-01-01T23:59:59.000Z

326

Biphasic catalysis in water/carbon dioxide micellar systems  

DOE Patents (OSTI)

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.

Jacobson, Gunilla B. (Los Alamos, NM); Tumas, William (Los Alamos, NM); Johnston, Keith P. (Austin, TX)

2002-01-01T23:59:59.000Z

327

Reduced ternary molybdenum and tungsten sulfides and hydroprocessing catalysis therewith  

DOE Patents (OSTI)

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.

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

1999-02-16T23:59:59.000Z

328

Charge Transfer and Catalysis at the Metal-Support Interface  

E-Print Network (OSTI)

S. J. ; Fung, S. C. ; Garten, R. L. J. Am. Chem. Soc. 1978,S. J. ; Fung, S. C. ; Garten, R. L. Journal of the AmericanS. J. ; Fung, S. C. ; Garten, R. L. Journal of the American

Baker, Lawrence Robert

2012-01-01T23:59:59.000Z

329

Charge Transfer and Support Effects in Heterogeneous Catalysis  

E-Print Network (OSTI)

S.  J. ; Fung, S.  C. ; Garten, R.  L.  J.  Am.  Chem.  S.  J. ; Fung, S.  C. ; Garten, R.  L.  J.  Am.  Chem.  S.  J. ; Fung, S.  C. ; Garten, R.  L.  J.  Am.  Chem.  

Hervier, Antoine

2012-01-01T23:59:59.000Z

330

Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis  

Science Conference Proceedings (OSTI)

The goal of our program is to define those modes of interaction that take place between organometallic molecules and inorganic surfaces and, ultimately, to correlate various molecule-surface structures with catalytic properties.

Marks, T.J.

1990-02-01T23:59:59.000Z

331

Density Functional Theory in Surface Chemistry and Catalysis  

SciTech Connect

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.

Norskov, Jens

2011-05-19T23:59:59.000Z

332

Hydrogen spillover: Its "diffusion" from catalysis to hydrogen storage community  

DOE Green Energy (OSTI)

Dissociative adsorption of hydrogen on catalyst sites followed by surface diffusion (spillover) to a carbon support was first reported for Pt-carbon catalysts (Robell, 1964) and was soon accepted as a valid step of numerous catalytic reactions. However, the concept of metal-assisted hydrogen storage (Schwarz, 1988) based on spillover entered much later the hydrogen community (Lueking and Yang, 2002) and is gaining recognition slowly as an alternate approach for enhancing hydrogen storage capacity of microporous materials for fuel-cell powered vehicles. This talk will analyze the significance and limits of the spillover mechanism for adsorptive storage of hydrogen, with examples of enhanced hydrogen uptake on Pd-containing activated carbon fibers. Evidence of the atomic nature of spilt-over hydrogen will be presented based on experimental results from inelastic neutron spectroscopy studies. Research sponsored by the Division of Materials Sciences and Engineering, U.S. Department of Energy under contract with UT-Battelle, LLC.

Contescu, Cristian I [ORNL; Bhat, Vinay V [ORNL; Gallego, Nidia C [ORNL

2009-01-01T23:59:59.000Z

333

SR protein kinase 1 : conformation, substrate recognition and catalysis  

E-Print Network (OSTI)

ID-19 of the Advanced Photon Source (APS) at ArgonneID-23 of the Advanced Photon Source (APS) at ArgonneID-19 of the Advanced Photon Source (APS) at Argonne

Ngo, Jacky Chi Ki

2006-01-01T23:59:59.000Z

334

Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis  

SciTech Connect

The long-range goal of this project is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. The nature of the adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecular-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

Marks, T.J.

1992-02-01T23:59:59.000Z

335

Workshop: In Situ Phenomena in Catalysis (May 3, 2011)  

NLE Websites -- All DOE Office Websites (Extended Search)

by combining ab-initio simulations and advanced characterization methods (i.e., HR-TEM, environmental-TEM, and EXAFS), structure- property relations in catalytic nano-particles...

336

Charge Transfer and Support Effects in Heterogeneous Catalysis  

E-Print Network (OSTI)

closely followed the  solar  spectrum.   On  a  typical closely followed the solar spectrum.   A batch mode reactor followed the solar spectrum.   Electrical  connections 

Hervier, Antoine

2012-01-01T23:59:59.000Z

337

Switching Catalysis from Hydrolysis to Perhydrolysis in Pseudomonas fluorescens Esterase  

SciTech Connect

Many serine hydrolases catalyze perhydrolysis, the reversible formation of peracids from carboxylic acids and hydrogen peroxide. Recently, we showed that a single amino acid substitution in the alcohol binding pocket, L29P, in Pseudomonas fluorescens (SIK WI) aryl esterase (PFE) increased the specificity constant of PFE for peracetic acid formation >100-fold [Bernhardt et al. (2005) Angew. Chem., Int. Ed. 44, 2742]. In this paper, we extend this work to address the three following questions. First, what is the molecular basis of the increase in perhydrolysis activity? We previously proposed that the L29P substitution creates a hydrogen bond between the enzyme and hydrogen peroxide in the transition state. Here we report two X-ray structures of L29P PFE that support this proposal. Both structures show a main chain carbonyl oxygen closer to the active site serine as expected. One structure further shows acetate in the active site in an orientation consistent with reaction by an acyl-enzyme mechanism. We also detected an acyl-enzyme intermediate in the hydrolysis of {var_epsilon}-caprolactone by mass spectrometry. Second, can we further increase perhydrolysis activity? We discovered that the reverse reaction, hydrolysis of peracetic acid to acetic acid and hydrogen peroxide, occurs at nearly the diffusion limited rate. Since the reverse reaction cannot increase further, neither can the forward reaction. Consistent with this prediction, two variants with additional amino acid substitutions showed 2-fold higher k{sub cat}, but K{sub m} also increased so the specificity constant, k{sub cat}/K{sub m}, remained similar. Third, how does the L29P substitution change the esterase activity? Ester hydrolysis decreased for most esters (75-fold for ethyl acetate) but not for methyl esters. In contrast, L29P PFE catalyzed hydrolysis of {var_epsilon}-caprolactone five times more efficiently than wild-type PFE. Molecular modeling suggests that moving the carbonyl group closer to the active site blocks access for larger alcohol moieties but binds {var_epsilon}-caprolactone more tightly. These results are consistent with the natural function of perhydrolases being either hydrolysis of peroxycarboxylic acids or hydrolysis of lactones.

Yin, D.; Bernhardt, P; Morley, K; Jiang, Y; Cheeseman, J; Purpero, V; Schrag, J; Kazlauskas, R

2010-01-01T23:59:59.000Z

338

Chapter 1 Introduction 1.1. HOMOGENEOUS CATALYSIS  

E-Print Network (OSTI)

acid Pt/Rh nets 1940 Catalytic reforming of hydrocarbons (gasoline) Pt/Al2O3 1940 Benzene hydrogenation

Groningen, Rijksuniversiteit

339

Catalysis of Propane Oxidation and Premixed Propane-Air Flames.  

E-Print Network (OSTI)

??Improvements in deriving energy from hydrocarbon fuels will have a large impact on our efforts to transition to sustainable and renewable energy resources. The hypothesis… (more)

Wiswall, James T.

2009-01-01T23:59:59.000Z

340

Progress in transition metal-based enantioselective catalysis  

E-Print Network (OSTI)

In Chapter 1, the first enantioselective cross-coupling reactions of racemic secondary benzylic halides are described (eq 1). This method was applied to the syntheses of intermediates employed by other groups in the ...

Arp, Forrest O

2008-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

When Catalysis is Useful for Probabilistic Entanglement Transformation  

E-Print Network (OSTI)

We determine all $2\\times 2$ quantum states that can serve as useful catalysts for a given probabilistic entanglement transformation, in the sense that they can increase the maximal transformation probability. When higher-dimensional catalysts are considered, a sufficient and necessary condition is derived under which a certain probabilistic transformation has useful catalysts.

Yuan Feng; Runyao Duan; Mingsheng Ying

2004-03-24T23:59:59.000Z

342

Computational Design of Lignin Depolymerization Catalysts  

Science Conference Proceedings (OSTI)

Lignin is a major component of plant cell walls that is typically underutilized in selective conversion strategies for renewable fuels and chemicals. The mechanisms by which thermal and catalytic treatments deconstruct lignin remain elusive, for which quantum mechanical calculations can offer fundamental insights. In this work, a computational approach has been used to elucidate the reductive deconstruction pathway of a ruthenium-catalyzed system. Transition states have been computed to determine the rate-limiting steps for a catalyst that cleaves arylether linkages. Our calculations are supported by experimental synthesis and kinetic and thermodynamic measurements of the deconstruction of model lignin dimers by a ruthenium catalyst with the ultimate objective of designing new catalysts to eventually utilize lignin in biorefineries.

Kim, S.; Chmely, S. C.; Sturgeon, M.; Katahira, R.; Paton, R. S.; Beckham, G. T.

2012-01-01T23:59:59.000Z

343

NIST Potential Energy Surface Database of Group II Dimers  

Science Conference Proceedings (OSTI)

... NIST , PML , Quantum Measurement Division Gaithersburg, Maryland 20899. Experimental, Ab-initio, and Semi-Empirical Potential Energy Curves. ...

2011-12-13T23:59:59.000Z

344

Role of Aluminum Dimer and Carbonate in the Aluminum ...  

observed in the aging experiment which is ~ 3X to WTP curve • Follow the solution composition and mass balance of these solutions over time using

345

NIST Poten. Energy Surfaces of Group II Dimers - Version ...  

Science Conference Proceedings (OSTI)

... database access date.) SA Kotochigova and PS Julienne (2010), Potential Energy Surface Database ... [Type of medium] Available: URL [Access date ...

2010-10-05T23:59:59.000Z

346

Probing Membrane Protein Dimerization in the Native Bilayer ...  

Science Conference Proceedings (OSTI)

... Native Bilayer Environment. Kalina Hristova, Department of Materials Science and Engineering Johns Hopkins University. ...

347

NIST Potential Energy Surfaces of Group II Dimers ...  

Science Conference Proceedings (OSTI)

... of Standards and Technology (NIST) uses its best efforts to deliver a high quality copy of the Database and to verify that the data contained therein ...

2010-10-05T23:59:59.000Z

348

Direct methanol oxidation on platinum electrodes with ruthenium adatoms in hot phosphoric acid  

Science Conference Proceedings (OSTI)

Enhancement of the electrocatalytic activity of platinum for direct methanol oxidation by Ru adatoms and by the elevation of operating temperatures was investigated in hot phosphoric acid (60 to 190 C). It is clear that a higher temperature operation (>100 C) is advantageous for the enhancement of methanol oxidation and a maximum enhancement by Ru adatoms at each operating temperature is obtained at Pt/Ru = 1/1. These results are quite similar to those obtained at low temperatures in 0.5 M H{sub 2}SO{sub 4}. The mechanism of the electrocatalysis on platinum electrodes with Ru adatoms in hot H{sub 3}PO{sub 4} is discussed based on the experimental data in comparison with those in 0.5 M H{sub 2}SO{sub 4}. The rate of methanol oxidation is proportional to Ru coverage ({theta}{sub Ru}{sup Pt}) by the introduction of Ru sites contributing to the adsorption of oxygen species required for the oxidation of the organic species absorbed on Pt sites in a Ru coverage region of {theta} {le} 0.5, but it is reduced inversely proportional to {theta} due to the reduction of a dissociative adsorption rate of methanol on the platinum sites in the region of {theta} > 0.5, where the coverage of organic species becomes zero.

Watanabe, Masahiro; Genjima, Yasuhiro [Yamanashi Univ., Kofu (Japan); Turumi, Kazunori [Tanaka Kikinzoku Kogyo Technical Center, Hiratsuka (Japan)

1997-02-01T23:59:59.000Z

349

Tailoring Selectivity for Electrocatalytic Oxygen Evolution on Ruthenium Oxides by Zn Substitution  

SciTech Connect

Controlling gas emissions: Versatile control of the selectivity of an oxide electrocatalyst in the oxygen- and chlorine-evolution reactions was demonstrated by Zn substitution in RuO{sub 2}. The incorporation of Zn into the rutile structure alters the cation sequence along the [001] direction and modifies the structure of the active sites for both gas-evolution processes.

Petrykin, V.; Macounova, K; Shlyakhtin, O; Krtil, P

2010-01-01T23:59:59.000Z

350

Chapter 3: Insights in the Hydrotreatment of Fast Pyrolysis Oil using a Ruthenium on Carbon Catalyst  

E-Print Network (OSTI)

pyrolysis oil and bio-liquids derived thereof. Fast pyrolysis oils can be obtained from biomass in yields up] Bridgwater, A.; Czernik, S.; Diebold, J.; Meier, D.; Oasmaa, A.; Peacocke, C,. Fast Pyrolysis of Biomass, I.A. Production of a Bio-Gasoline by Ugrading Biomass Flash Pyrolysis Liquids via Hydrogen

Groningen, Rijksuniversiteit

351

Atomistic description of oxide formation on metal surfaces: the example of ruthenium  

E-Print Network (OSTI)

energy, Ewf , and for the potential repre- sentation in the interstitial region, plane waves with kinetic;Ewf = 12.5 Ry (Mg and Ti), 14.1 Ry (Al and Pd), and 16.7 Ry (Cu and Pt); Rmt = 1.27 A° (Mg, Ti, Al

352

THE MECHANISM AND KINETICS OF FISCHER-TROPSCH SYNTHESIS OVER SUPPORTED RUTHENIUM CATALYSTS  

E-Print Network (OSTI)

R. B. , "The Fischer- Tropsch and Related Syntheses", Wiley,Anderson, R. , "The Fischer-Tropsch and Related Synthesis",Isotope Effects on Fischer-Tropsch Synthesis Over Supported

Kellner, Carl Stephen

2013-01-01T23:59:59.000Z

353

Interaction of carbon monoxide and hydrogen with the (1010) face of ruthenium  

DOE Green Energy (OSTI)

The interaction was studied at 23.5, 200, and -135/sup 0/C with low energy electron diffraction (LEED) and Auger electron spectroscopy. (AES). Carbon monoxide adsorbs associatively at 23.5/sup 0/C, but is apparently dissociated by the LEED beam and hydrogen adsorbed from the ambient after a few minutes for less than 10 Langmuirs of carbon monoxide. For large doses of carbon monoxide at 23.5/sup 0/C, 10 Langmuirs or more, the LEED beam does not disociate carbon monoxide, but carbon monoxide and hydrogen adsorbed from the ambient do appear to be removed from the surface by the LEED beam. Carbon monoxide and hydrogen on the surface together will react and form surface complexes with distinctive LEED patterns at 23.5/sup 0/C though some of the interactions appear to be LEED beam induced. If sufficient hydrogen is present, some of these complexes are lost from the surface probably as methane and water. Carbon monoxide will react with itself and hydrogen at 23.5/sup 0/C with carbon being lost from the surface probably as carbon dioxide. At 200/sup 0/C, neither carbon monoxide nor hydrogen will absorb on Ru (1010) in significant amounts at the low dose pressures used. However, if the Ru(1010) crystal is allowed to cool below 70/sup 0/C, ambient carbon monoxide and hydrogen will adsorb on Ru (1010) and form LEED patterns like those formed at 23.5/sup 0/C. At -135/sup 0/C, carbon monoxide will react with itself and hydrogen readily most of the time producing surface complexes with distinctive LEED paterns. If a moderate amount of hydrogen is present, some of these complexes are lost from the surface, probably as methane. If a large amount of hydrogen is present, some of these complexes are lost from the surface probably as carbon dioxdie. 17 figures, 8 tables.

Tomcsik, T.L.

1979-01-01T23:59:59.000Z

354

Electrochemical and XRD characterization of platinum-ruthenium blacks for DMFC anodes.  

DOE Green Energy (OSTI)

It is generally accepted that Pt-Ru alloy catalysts with an atomic Pt-to-Ru ratio of 1:1 generate the best anode perform'ance in the direct methanol fuel cell (DMFG). However, at near-ambient cell operating temperatures, Gasteiger et al. reported that a catalyst with significantly lower Ru content, {approx} 10 at %, offers the highest activity towards methanol. Recently, Dinh et al. demonstrated that the activity of different Pt-Ru catalysts with the same Pt-to-Ru atomic ratio in the bulk might vary depending on the actual surface composition, which is often significantly different from that in the bulk phase, In this work, we study several experimental Pt-Ru catalysts (Johnson Matthey) with Pt-to-Ru atomic ratio ranging from 9: 1 to 1 :2. Electrocatalytic activity of these catalysts in methanol oxidation reaction is investigated in a regular DMFC 'and probed using voltammetric stripping of surhce CO.

Eickes, C. (Christian); Brosha, E. L. (Eric L.); Garzon, F. H. (Fernando H.); Purdy, G. M. (Geraldine M.); Zelenay, P. (Piotr); Morita, T. (Takanari); Thompsett, D. (David)

2002-01-01T23:59:59.000Z

355

Selective oxidation of methanol and ethanol on supported ruthenium oxide clusters at low temperatures  

DOE Green Energy (OSTI)

RuO2 domains supported on SnO2, ZrO2, TiO2, Al2O3, and SiO2 catalyze the oxidative conversion of methanol to formaldehyde, methylformate, and dimethoxymethane with unprecedented rates and high combined selectivity (>99 percent) and yield at low temperatures (300-400 K). Supports influence turnover rates and the ability of RuO2 domains to undergo redox cycles required for oxidation turnovers. Oxidative dehydrogenation turnover rates and rates of stoichiometric reduction of RuO2 in H2 increased in parallel when RuO2 domains were dispersed on more reducible supports. These support effects, the kinetic effects of CH3OH and O2 on reaction rates, and the observed kinetic isotope effects with CH3OD and CD3OD reactants are consistent with a sequence of elementary steps involving kinetically relevant H-abstraction from adsorbed methoxide species using lattice oxygen atoms and with methoxide formation in quasi-equilibrated CH3OH dissociation on nearly stoichiometric RuO2 surfaces. Anaerobic transient experiments confirmed that CH3OH oxidation to HCHO requires lattice oxygen atoms and that selectivities are not influenced by the presence of O2. Residence time effects on selectivity indicate that secondary HCHO-CH3OH acetalization reactions lead to hemiacetal or methoxymethanol intermediates that convert to dimethoxymethane in reactions with CH3OH on support acid sites or dehydrogenate to form methylformate on RuO2 and support redox sites. These conclusions are consistent with the tendency of Al2O3 and SiO2 supports to favor dimethoxymethane formation, while SnO2, ZrO2, and TiO2 preferentially form methylformate. These support effects on secondary reactions were confirmed by measured CH3OH oxidation rates and selectivities on physical mixtures of supported RuO2 catalysts and pure supports. Ethanol also reacts on supported RuO2 domains to form predominately acetaldehyde and diethoxyethane at 300-400 K. The bifunctional nature of these reaction pathways and the remarkable ability of RuO2-based catalysts to oxidize CH3OH to HCHO at unprecedented low temperatures introduce significant opportunities for new routes to complex oxygenates, including some containing C-C bonds, using methanol or ethanol as intermediates derived from natural gas or biomass.

Liu, Haichao; Iglesia, Enrique

2004-03-04T23:59:59.000Z

356

N-butane activation over ruthenium and iron promoted VPO catalysts.  

E-Print Network (OSTI)

??The Fe- and Ru-promoted vanadium phosphorus oxide (VPO) catalysts were synthesized via the organic route in iso-butanol to form the VPO precursor, VOHPO4·0.5H2O. The resulting… (more)

Masilo, Neoentle.

2009-01-01T23:59:59.000Z

357

Iridium?Ruthenium Alloyed Nanoparticles for the Ethanol Oxidation Fuel Cell Reactions  

DOE Green Energy (OSTI)

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.

Su D.; Du, W.; Deskins, N.A.; Teng, X.

2012-06-01T23:59:59.000Z

358

Method of tagging sand with ruthenium-103 and the resultant product  

DOE Patents (OSTI)

A procedure for tagging sand with a radioisotope for use in the study of sediment transport involves the precipitation of a metal radioisotope in the form of an iodide directly on the sand, followed by heating the sand to a temperature sufficient to effect a phase transformation of the sand and a decomposition of the metal iodide, leaving the metal firmly attached to the sand.

Case, Forrest N. (Oak Ridge, TN); McFarland, Clyde E. (Knoxville, TN)

1976-01-01T23:59:59.000Z

359

The Influence of Ruthenium and Rhenium on the Local Properties of ...  

Science Conference Proceedings (OSTI)

superalloys to gain good high temperature properties combined ... The alloys were investigated in standard heat treated state, after ...... power, eds. C. T. Sims et ...

360

CO oxidation over ruthenium: identification of the catalytically active phases at near-atmospheric pressures  

SciTech Connect

CO oxidation was carried out over Ru(0001) and RuO2(110) thin film grown on Ru(0001) at various O2/CO ratios near atmospheric pressures. Reaction kinetics, coupled with in situ polarization modulation infrared reflection absorption spectroscopy (PM-IRAS) and post-reaction Auger electron spectroscopy (AES) measurements were used to identify the catalytically relevant phases at different reaction conditions. Under stoichiometric and reducing conditions at all reaction temperatures, as well as net-oxidizing reaction conditions below {approx}475 K, a reduced metallic phase with chemisorbed oxygen is the thermodynamically stable and catalytically active phase. On this surface CO oxidation occurs at surface defect sites, for example step edges. Only at net-oxidizing reaction conditions and above {approx}475 K is the RuO2 thin film grown on metallic Ru stable and active. However, RuO2 is not active itself without the existence of the metal substrate, suggesting the importance of a strong metal-substrate interaction (SMSI).

Gao, Feng; Goodman, Wayne D.

2012-05-21T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Effects of the reaction cavity on metastable optical excitation in ruthenium-sulfur dioxide complexes  

SciTech Connect

We report photoexcited-state crystal structures for two new members of the [Ru(SO{sub 2})(NH{sub 3}){sub 4}X]Y family: 1:X=H{sub 2}O, Y=({+-})-camphorsulfonate{sub 2}; 2:X=isonicotinamide, Y=tosylate{sub 2}. The excited states are metastable at 100 K, with a photoconversion fraction of 11.1(7)% achieved in 1, and 22.1(10)% and 26.9(10)% at the two distinct sites in 2. We further show using solid-state density-functional-theory calculations that the excited-state geometries achieved are strongly influenced by the local crystal environment. This result is relevant to attempts to rationally design related photoexcitation systems for optical data-storage applications.

Phillips, Anthony E.; D'Almeida, Thierry; Low, Kian Sing [Department of Physics, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Cole, Jacqueline M. [Department of Physics, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Department of Chemistry, University of New Brunswick, P.O. Box 4400, Fredericton, New Brunswick, E3B5A3 (Canada); Department of Physics, University of New Brunswick, P.O. Box 4400, Fredericton, New Brunswick, E3B5A3 (Canada)

2010-10-15T23:59:59.000Z

362

Direct catalytic conversion of methane and light hydrocarbon gases. Quarterly report No. 5, November 16, 1987--January 15, 1988  

DOE Green Energy (OSTI)

The goal of this research is to develop catalysts that directly convert methane and light hydrocarbons to intermediates that later can be converted to either liquid fuels or value-added chemicals, as economics dictate. During this reporting period, we have synthesized and tested several novel catalysts for methane reforming (Tasks 1 and 2) and for partial oxidation of methane (Tasks 3 and 4). We started to test a mixed metal system, an FeRu{sub 3} cluster. This catalyst was supported both on zeolite and on magnesium oxide and the systems were tested for methane reforming at various reaction temperatures. We also prepared and tested a monomeric ruthenium catalyst supported on magnesium oxide. We found that methane is activated at a lower temperature with the basic magnesium oxide support than with acidic supports such as zeolite or alumina. Methane conversions increased with temperature, but the production of coke also increased. We prepared a sterically hindered ruthenium porphyrin encapsulated in a zeolite supercage for catalysis of methane oxidation. The results showed that only carbon dioxide was produced. Addition of axial base to this catalyst gave similar results. Another type of catalyst, cobalt Schiff base complexes, was also prepared and tested for methane oxidation. In this case, no methane conversion was observed at temperatures ranging from 200 to 450{degrees}C. These complexes do not appear to be stable under the reaction conditions.

Wilson, R.B. Jr.; Chan Yee Wai

1988-02-05T23:59:59.000Z

363

ORIGINAL PAPER Conceptual design of carbon nanotube processes  

E-Print Network (OSTI)

various heterogeneous catalysts Ruthenium Catalysts.....................................................................................3-1 PART I: The Application of Water-soluble Ruthenium Catalysts for the Hydrogenation

Pike, Ralph W.

364

Catalysis Today 77 (2002) 6578 CO-free fuel processing for fuel cell applications  

E-Print Network (OSTI)

to the manufacture of many products including fuels, plastics, and pharmaceuticals. Without catalysts and catalytic lives would not be possible. The purpose of this primer is to show why catalysts are required, polymers, and pharmaceuticals. As we shall see, catalysts are the ultimate enablers of chemical

Goodman, Wayne

365

Investigation on application of homogeneous and heterogeneous catalysis for alkaline waste treatment  

SciTech Connect

The stabilization of neptunium(IV) in alkaline solution by chemical reductants under various conditions was studied. Testing showed that neptunium(V) is slowly reduced to Np(IV) by V(IV) at room temperature in alkaline solutions. Increasing temperature accelerates reduction. Complete reduction of 2 x 10{sup -4} M Np(V) occurs in three hours at 80{degrees}C in 1 M NaOH with 0.02 M VOSO{sub 4-}. Under similar conditions, but in 5 M NaOH, only 15 to 20% of the Np(V) was reduced in 5 hours. In all cases, about 98 % of the initial neptunium was found in the precipitate. Thus V(IV) acts both as a reductant and as a precipitation carrier. Tests showed Np(V) reduction by hydrazine hydrate could be catalyzed by Pd(II). Reduction increased with temperature and catalyst concentration and decreased with hydroxide concentration. Reduction of Np(V) also takes place in 1 M NaOH solutions containing 1 M sodium formate and palladium. Increasing temperature accelerates reduction; with three hours` treatment in 5 M NaOH solution at 90{degrees}C, about 95 % of the initial 2 x 10{sup -4} M neptunium(V) is transformed to Np(IV). Organic complexants and organic acid anions hinder the decontamination of alkaline solutions from neptunium and plutonium by coprecipitation with d-element hydroxides (the Method of Appearing Reagents). It was found that ethylenediaminetetraacetate (EDTA) and N-(2-hydroxyethyl) ethylenediaminetriacetate (HEDTA) are decomposed by H{sub 2}O{sub 2} in alkaline solution in the presence of cobalt compounds with heating and by Na2S208 at moderate temperatures. Citrate, glycolate, and oxalate are decomposed by Na{sub 2}S{sub 2}O{sub 8} with heating. Oxidant amounts must be increased when NaNO{sub 2} also is present in solution. 8 refs., 25 figs., 16 tabs.

Shilov, V.P.; Bessonov, A.A.; Garnov, A.Y.; Gelis, A.V. [Russian Academy of Sciences, Moscow (Russian Federation). Institute of Physical Chemistry] [and others

1997-09-01T23:59:59.000Z

366

Catalysis of Reduction and Oxidation Reactions for Application in Gas Particle Filters  

SciTech Connect

The present study is a first part of an investigation addressing the simultaneous occurrence of oxidation and reduction reactions in catalytic filters. It has the objectives (a) to assess the state of knowledge regarding suitable (types of) catalysts for reduction and oxidation, (b) to collect and analyze published information about reaction rates of both NOx reduction and VOC oxidation, and (c) to adjust a lab-scale screening method to the requirements of an activity test with various oxidation/reduction catalysts.

Udron, L.; Turek, T.

2002-09-19T23:59:59.000Z

367

The Synthesis of Novel Metal and Metal Oxide Nanoparticles with Applications Towards Catalysis  

E-Print Network (OSTI)

crisis because (unlike petroleum based sources), they arewith depletion of petroleum- based energy sources has led

McMurdo, Meredith Joanne

2010-01-01T23:59:59.000Z

368

Catalysis Today 59 (2000) 4760 A critical evaluation of NavierStokes, boundary-layer,  

E-Print Network (OSTI)

for conditions that are typical of the catalytic combustion of natural gas. In developing simulation capabilities ultra-low emission of NOx in applications like gas turbines for electric-power gen- eration [1-value problem for the axial variation of the mean species composition. An intermediate alternative is to base

Raja, Laxminarayan L.

369

Nanocomposite materials designed for chemical catalysis. Final progress report, 1 May 1995--31 December 1998  

Science Conference Proceedings (OSTI)

The specific aim of this research project is the development of novel methods for preparing improved catalysts for direct methanol fuel cells (DMFCs). These catalysts consist of metal alloy nanoclusters dispersed onto a conductive carbon support. Synthetic control of the alloy nanocluster composition is achieved by preparing molecular precursors in which the precursor contains two or more metals of a desired stoichiometry. Adsorption of single-source molecular precursors onto Vulcan carbon powder followed by appropriate thermal treatment affords metal alloy or intermetallic/carbon nanocomposites having thirteen different binary compositions and one ternary composition. Tests performed in an operating DMFC indicate that the catalytic activity of two PtRu/Vulcan carbon nanocomposites as anode catalysts is superior to that of a similar commercial PtRu/Vulcan carbon catalyst. A rapid synthesis of such binary alloy/Vulcan carbon nanocomposites using microwave heating has been discovered. Preliminary attempts to prepare passivated metal nanoclusters suitable for size selection are also discussed. The preparation of an unrelated cobalt/fullerene nanocomposite is included for completeness.

Lukehart, C.M.

1999-03-29T23:59:59.000Z

370

Plasma Catalysis for NOx Reduction from Light-Duty Diesel Vehicles  

SciTech Connect

The control of NOx (NO and NO2) emissions from so-called ‘lean-burn’ vehicle engines remains a challenge. In this program, we have been developing a novel plasma/catalyst technology for the remediation of NOx under lean (excess oxygen) conditions, specifically for compression ignition direct injection (CIDI) diesel engines that have significant fuel economy benefits over conventional stoichiometric gasoline engines. Program efforts included: (1) improving the catalyst and plasma reactor efficiencies for NOx reduction; (2) studies to reveal important details of the reaction mechanism(s) that can then guide our catalyst and reactor development efforts; (3) evaluating the performance of prototype systems on real engine exhaust; and (4) studies of the effects of the plasma on particulate matter (PM) in real diesel engine exhaust. Figure 1 is a conceptual schematic of a plasma/catalyst device, which also shows our current best understanding of the role of the various components of the overall device for reducing NOx from the exhaust of a CIDI engine. When this program was initiated, it was not at all clear what the plasma was doing and, as such, what class of catalyst materials might be expected to produce good results. With the understanding of the role of the plasma (as depicted in Figure 1) obtained in this program, faujasite zeolite-based catalysts were developed and shown to produce high activity for NOx reduction of plasma-treated exhaust in a temperature range expected for light-duty diesel engines. These materials are the subject of a pending patent application, and were recognized with a prestigious R&D100 Award in 2002. In addition, PNNL staff were awarded a Federal Laboratory Consortium (FLC) Award in 2003 “For Excellence in Technology Transfer”. The program also received the DOE’s 2001 CIDI Combustion and Emission Control Program Special Recognition Award and 2004 Advanced Combustion Engine R&D Special Recognition Award.

Barlow, Stephan E.; Kwak, Ja Hun; Peden, Charles HF; Szanyi, Janos; Tonkyn, Russell G.; Howden, Ken; Hoard, John W.; Cho, Byong; Schmieg, Steven J.; Brooks, David J.; Nunn, Steven; Davis, Patrick

2004-12-31T23:59:59.000Z

371

Synergies of PCCI-Type Combustion and Lean NOx Trap Catalysis for Diesel Engines  

Science Conference Proceedings (OSTI)

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.

Parks, II, James E [ORNL; Prikhodko, Vitaly Y [ORNL; Kass, Michael D [ORNL; Huff, Shean P [ORNL

2008-01-01T23:59:59.000Z

372

Superacid catalysis of light hydrocarbon conversion. Ninth quarterly report, October 1, 1995--December 31, 1995  

DOE Green Energy (OSTI)

Transition metal promoters of sulfated zirconia increase its catalytic activity for the conversion of n-butane. The promoter effects vary from one transition metal to another in the family zinc, iron, nickel, cobalt, and manganese. The most active catalyst so far tested is promoted by both iron and manganese. This catalyst is two or more orders of magnitude more active than unpromoted sulfated zirconia. The manganese promoter alone markedly increases the catalytic activity, but the activity declines very rapidly with time on stream in the flow reactor. Under the same experimental conditions, iron has a smaller but longer-lasting effect as a promoter than manganese, and to a first approximation, the iron- and manganese-promoted catalyst shows a behavior that is a superposition of those of the two individual promoters.

Gates, B.C. [California Univ., Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

1995-12-31T23:59:59.000Z

373

Neutron scattering characterization of pure and rare-earth modified zirconia catalysis.  

SciTech Connect

The combined application of neutron powder diffraction, small angle neutron scattering and neutron inelastic scattering has led to improved understanding of the crystal phases, defect structure, microstructure and hydroxyl/water dynamics in pure and lanthanide-modified zirconia catalysts. Powder diffraction experiments quantified the degree of stabilization and provided evidence for static, oxygen vacancy-induced atomic displacements in stabilized zirconia. Quantitative assessment of Bragg peak breadths led to measurements of ''grain size'', representing coherency length of long-range ordered atomic arrangements (crystals). Small angle neutron scattering provided a separate measurement of ''grain size'', representing the average size of the primary particles in the aggregates, and the evolution of porosity (micro- versus meso-) and surface roughness caused by RE modification and heat treatment. Finally, the dynamics of hydrogen atoms associated with surface hydroxyls and adsorbed water was investigated by neutron-inelastic scattering, revealing changes in frequency and band breadth of O-H stretch, H-O-H bend, and librational motion of water molecules.

Loong, C.-K.; Ozawa, M.; Richardson, J. W., Jr.; Suzuki, S.; Thiyagarajan, P.

1997-11-18T23:59:59.000Z

374

A Hierarchy of Timescales in Protein Dynamics is Linked to Enzyme Catalysis  

SciTech Connect

The synergy between structure and dynamics is essential to the function of biological macromolecules. Thermally driven dynamics on different timescales have been experimentally observed or simulated, and a direct link between micro- to milli-second domain motions and enzymatic function has been established. However, very little is understood about the connection of these functionally relevant, collective movements with local atomic fluctuations, which are much faster. Here we show that pico- to nano-second timescale atomic fluctuations in hinge regions of adenylate kinase facilitate the large-scale, slower lid motions that produce a catalytically competent state. The fast, local mobilities differ between a mesophilic and hyperthermophilic adenylate kinase, but are strikingly similar at temperatures at which enzymatic activity and free energy of folding are matched. The connection between different timescales and the corresponding amplitudes of motions in adenylate kinase and their linkage to catalytic function is likely to be a general characteristic of protein energy landscapes.

Henzler-Wildman,K.; Lei, M.; Thai, V.; Jordan Kerns, S.; Karplus, M.; Kern, D.

2007-01-01T23:59:59.000Z

375

Journal of Molecular Catalysis A: Chemical 228 (2005) 299307 Complementary methods for cluster size distribution measurements  

E-Print Network (OSTI)

size distribution measurements: supported platinum nanoclusters in methane reforming catalysts J.V. All rights reserved. Keywords: Cluster size; SAXS; XAFS; HRTEM; Methane reforming 1. Introduction cluster size strongly influences the reactivity of surfaces for C H bond activation during CH4 steam

Iglesia, Enrique

376

Applied Catalysis A: General 469 (2014) 275283 Contents lists available at ScienceDirect  

E-Print Network (OSTI)

from the standpoint of energy efficiency, compared to endothermic steam reforming (Eq. (2)) and dry2O3 or Ce0.5Zr0.5O2 supports for the partial oxidation of methane Alejandro J. Santis Catalytic partial oxidation Flame spray synthesis a b s t r a c t Catalytic partial oxidation of methane

Daraio, Chiara

377

Catalysis Letters Vol. 77, No. 13, 2001 1 Ammonia decomposition on Ir(100)  

E-Print Network (OSTI)

hydrogen pro- duction technologies such as steam reforming, partial oxida- tion and autothermal reforming reforming of methane/hydrocarbons as a method for production of CO-free hydrogen [3,4]. An alternative for hydrogen production for applications in fuel cells [3­6]. Recently we have pro- posed stepwise steam

Goodman, Wayne

378

Gold(I)-Mediated Nucleophilic Additions to Allenes: from Enantioselective Catalysis to Supramolecular Chemistry  

E-Print Network (OSTI)

Pd/C for the synthesis of catechols from monosubstitutedled to formation of both catechols and tetrahydrodiols. Thisquantitites of fluoro-catechol from fluorobenzene. Figure

Wang, Zhan

2012-01-01T23:59:59.000Z

379

Selective molecular recognition, C-H bond activation, and catalysis in nanoscale reaction vessels  

E-Print Network (OSTI)

6 ] 11- . Six bis-bidentate catechol amide ligands span thenaphthalene based bis-bidentate catechol ligands (Figure 1).

Fiedler, Dorothea; Leung, Dennis H.; Raymond, Kenneth N.; Bergman, Robert G.

2004-01-01T23:59:59.000Z

380

Acid Catalysis in Basic Solution: A Supramolecular Host Promotes Orthoformate Hydrolysis  

E-Print Network (OSTI)

guests shows that the catechol oxygens are not accessible tonot between the guest and catechol protons (Fig. S1). 32. J.

Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Three-Dimensional Polypeptide Architectures Through Tandem Catalysis and Click Chemistry  

E-Print Network (OSTI)

product was a clear, colorless oil. No further purificationwas an opaque colorless oil (13.4 g crude isolated, 69%isolated as a clear, colorless oil. 1 H NMR (500 MHz, CDCl

Rhodes, Allison Jane

2013-01-01T23:59:59.000Z

382

Pacific Northwest National Laboratory: INstItute for INterfacIaL cataLysIs  

E-Print Network (OSTI)

shell (biomass) cellulosa type of reaction flash pyrolysis pyrolysis flash pyrolysis slow pyrolysis. Scott, J. Piskorz, D. Radlein; Liquid Products from the Continuous Flash Pyrolysis of Biomass, Ind. Eng; The Continous Flash Pyrolysis of Biomass, The Canadian Journal of Chemical Engineering, 1984, 62, 404-412 #12

383

Heterogeneous catalysis in fluoride melts: reduction of uranium(V) and niobium(IV) by hydrogen  

DOE Green Energy (OSTI)

The reduction of uranium(V) or niobium(IV) dissolved in fluoride melts at 550/sup 0/C by hydrogen gas in the absence of catalysts exhibits zero-order kinetics, i.e., the quantity reduced per unit time is independent of the concentration of dissolved species or the hydrogen gas partial pressure. Platinum catalysts accelerate the reaction rate 10- to 100-fold and, with uranium(V), the catalyzed reaction exhibits first-order kinetics, suggesting that the catalyzed reaction may be diffusion limited. Platinum was catalytically active when present as platinum black powder, sponge, sheet or powder that has sintered to or alloyed with the gold reaction crucible.

Kelmers, A.D.; Bennett, M.R.

1976-01-01T23:59:59.000Z

384

Monitoring the kinetics and thermodynamics of interfacial enzymatic catalysis by differential scanning calorimetryq  

E-Print Network (OSTI)

DPPC by molecular dynamics simulation [35]. We propose that the newly formed aggregate at the end of biochemical processes: activa- tion of phospholipase A2, Thermochim. Acta 172 (1990) 1­10. [9] L. Yu, E by the hydrolysis of phospholipase A2 enzyme: a molecular dynamics simulation study, Biophys. J. 80 (2001) 565

Luhua, Lai

385

Consequences of Structure and Composition for Catalysis by Solid and Bronsted Acids  

E-Print Network (OSTI)

thermochemical cycles of DPE and HAE were calculated using periodic gradient-corrected density functional theory (DFT) via the Vienna ab initio Simulation

Carr, Robert Ted

2012-01-01T23:59:59.000Z

386

Computational heterogeneous catalysis applied to steam methane reforming over nickel and nickel/silver catalysts  

E-Print Network (OSTI)

The steam methane reforming (SMR) reaction is the primary industrial means for producing hydrogen gas. As such, it is a critical support process for applications including petrochemical processing and ammonia synthesis. ...

Blaylock, Donnie Wayne

2011-01-01T23:59:59.000Z

387

Three-Dimensional Polypeptide Architectures Through Tandem Catalysis and Click Chemistry  

E-Print Network (OSTI)

Co(PMe 3 ) 4 and depeNi(COD) Initiators” TEACHING EXPERIENCE21 o C, 1 h. (b) dmpeNi(COD), DMF, 80 o C, 16 h. (c) 4.0 Mof Co(PMe 3 ) 4 and depeNi(COD) polymerization initiators,

Rhodes, Allison Jane

2013-01-01T23:59:59.000Z

388

Ylides: Stabilization of Novel, Low Valent Carbon-Based Ligands with Applications in Catalysis  

E-Print Network (OSTI)

2 Dipp NBS N PBr 3 Dipp N Ni(COD) 2 Dipp N X PPh 3 Br PPh 39 P Ph 2 Li(thf) x P 8 Ph 2 [RhCl(COD)] 2 Dipp N Rh -LiCl10 P Ph 2 CO -COD Dipp CO N Rh CO 11 P Ph 2 Scheme 2.4.

Asay, Matt

2009-01-01T23:59:59.000Z

389

The Synthesis of Novel Metal and Metal Oxide Nanoparticles with Applications Towards Catalysis  

E-Print Network (OSTI)

with the rhodium source [(COD)Rh(NCCH 3 ) 2 ]BF 4 , and theof the reactants [(COD)Rh(NCCH 3 ) 2 ] BF 4 , (Bu 4 N) 2 HPOThe rhodium precursor chosen was [(COD)RhCl] 2 (COD = 1,5-

McMurdo, Meredith Joanne

2010-01-01T23:59:59.000Z

390

The Synthesis of Novel Metal and Metal Oxide Nanoparticles with Applications Towards Catalysis  

E-Print Network (OSTI)

GADDS Diffractometer with a CoK ? X-ray source (? = 1.79026GADDS Diffractometer with a CoK ? X-ray source (? = 1.79026

McMurdo, Meredith Joanne

2010-01-01T23:59:59.000Z

391

Three-Dimensional Polypeptide Architectures Through Tandem Catalysis and Click Chemistry  

E-Print Network (OSTI)

M. ; Hecht, S. Polymer Chemistry 2010, 1, 69-71. North, M. ;Schmidt, M. Macromolecular Chemistry and Physics 2005, 206,J. Journal of Organometallic Chemistry 1999, 589, 111-114.

Rhodes, Allison Jane

2013-01-01T23:59:59.000Z

392

High pressure heterogeneous catalysis in a low pressure ultrahigh vacuum environment  

DOE Green Energy (OSTI)

An apparatus was been developed which couples high resolution electron energy loss spectroscopy with molecular beam and scattering techniques. Exposure of Ni(111) to atomic H results in H embedded within the Ni lattice and a monolayer of H adsorbed on the surface. This surface-bound H was removed by an Xe atom beam. Subsequent exposure to CH[sub 4] results in dissociative adsorption, producing adsorbed CH[sub 3] and adsorbed H. Results documents a new mechanism for a surface reaction, a reaction between an adsorbed and a bulk species, and demonstrates the importance of bulk H as a reactant in a heterogeneous catalytic reaction.

Ceyer, S.T.

1992-01-01T23:59:59.000Z

393

Transition metal catalysis in the generation of petroleum and natural gas. Progress report, [1992--1993  

DOE Green Energy (OSTI)

A new hypothesis is introduced for the generation of petroleum and natural gas. The transition metals, activated under the reducing conditions of diagenesis, are proposed as catalysts in the generation of light hydrocarbons. The objective of this proposal is to test that hypothesis. Transition metals (Ni, V, Ti, Co, Fe), in kerogen, porphyrins, and as pure compounds, will be tested under catagenic conditions for catalytic activity in the conversion of normal paraffins and hydrogen into light hydrocarbons. If the hypothesis is correct, kerogenous transition metals should become catalytically active under the reducing conditions of diagenesis and catalyze the conversion of paraffins into the light hydrocarbons seen in petroleum. Moreover, the C{sub 1}-C{sub 4} hydrocarbons generated catalytically should be similar in molecular and isotopic compositions to natural gas.

Mango, F.

1993-08-01T23:59:59.000Z

394

Pacific Northwest National Laboratory: INstItute for INterfacIaL cataLysIs  

E-Print Network (OSTI)

of Chemistry University of Calgary,Alberta, Canada T2N 1N4 New Orleans National Meeting Modeling the Fischer-Tropsch study Fischer-Tropsch synthesis: An Introduction First discovered by Sabatier and Sanderens in 1902: CO + H2 CH4 Ni,Fe,Co Fischer and Tropsch reported in 1923 the synthesis of liquid hydrocarbons with high

395

Journal of Catalysis 211, 422433 (2002) doi:10.1006/jcat.2002.3749  

E-Print Network (OSTI)

Conv. & Reform. Gasoline Conv. & Reform. Gasoline Conv. & Reform. Gasoline Fischer-Tropsch Diesel. & Reform. Gasoline Fischer-Tropsch Diesel and Naphtha Conv. & Reform. Gasoline Conv. & Reform. Gasoline, dimethyl ether, Fischer-Tropsch diesel, and biodiesel Spark-Ignition Direct-Injection Vehicles

Iglesia, Enrique

396

ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis  

E-Print Network (OSTI)

size e?ect in the Fischer-Tropsch synthesis. ” Stud. Surf.E. Rytter, A. Holmen ”Fischer-Tropsch synthesis over ?-Al 2Rytter, A. Holmen ”Fischer-Tropsch synthesis on Co supported

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

397

Journal of Catalysis 248 (2007) 165174 www.elsevier.com/locate/jcat  

E-Print Network (OSTI)

and unconventional sources (oil and sands and oil shale), Fisher-Tropsch jet fuel from natural gas, coal and biomass....................................................................................27 6 Fischer-Tropsch Jet Fuel.....................................................................................................29 6.1 Carbon Capture and Sequestration with Fischer-Tropsch Facilities

Regalbuto, John R.

398

Functionalized Nanoparticles and Surfaces for Controlled Chemical Catalysis and Effective Light Harvesting  

SciTech Connect

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.

Marye Anne Fox, James K. Whitesell

2012-11-02T23:59:59.000Z

399

Plasma Catalysis for NOx Reduction from Light-Duty Diesel Vehicles  

DOE Green Energy (OSTI)

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.

None

2005-12-15T23:59:59.000Z

400

ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis  

E-Print Network (OSTI)

04, France Institut f¨ r Chemie, Freie Universit¨ t Berlin,Angewandte und Physikalische Chemie, Universit¨ t Bremen, uKuebel, R. Richards Angew. Chemie Int. Ed. , 45 (2006) 7277;

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Evolution of the Surface Science of Catalysis from Single Crystals to Metal Nanoparticles under Pressure  

E-Print Network (OSTI)

P. D. Yang, Angewandte Chemie-International Edition 2006,G. M. Schwab, Angewandte Chemie-International Edition 1967,

Somorjai, Gabor A.

2008-01-01T23:59:59.000Z

402

The 13th International Symposium on Relations between Homogeneous and Heterogeneous Catalysis -- An Introduction  

E-Print Network (OSTI)

P. D. Yang, Angewandte Chemie-International Edition 2006,G. M. Schwab, Angewandte Chemie-International Edition 1967,

Somorjai, Gabor A.

2008-01-01T23:59:59.000Z

403

Three-Dimensional Polypeptide Architectures Through Tandem Catalysis and Click Chemistry  

E-Print Network (OSTI)

Zeitschrift Fur Physiologische Chemie 1969, 350,1183-1189.Kricheld.Hr Makromolekulare Chemie-Macromolecular ChemistryT. Journal Fur Praktische Chemie-Leipzig 1930, 125, 211-218.

Rhodes, Allison Jane

2013-01-01T23:59:59.000Z

404

Surface functionalization of metal?organic polyhedron for homogeneous cyclopropanation catalysis  

Science Conference Proceedings (OSTI)

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.

Lu, Weigang; Yuan, Daqiang; Yakovenko, Andrey; Zhou, Hong-Cai (TAM)

2012-03-13T23:59:59.000Z

405

Final Report for: "Bis-pi-allylpalladium Complexes in Catalysis of Multicomponent Reactions"  

Science Conference Proceedings (OSTI)

The research project involved the development of new and functionally improved Pd(II) catalyst for a three-component reaction of boronic acids, allenes and imines to afford homoallylic amines that are useful in synthesis of biologically active heterocycles. Furthermore, insights into the reaction mechanism and the structure and reactivity of the catalytically active intermediates involved in this process were sought. As a result of this work, a new type of Pd-catalysts possessing an auxiliary ligand attached to the Pd center via a C-Pd and N-Pd bonds were identified, and found to be more active than the traditional catalysts derived from Pd(OAc)2. The new catalysts provided an access to a broader range of homoallylic amine products. Although the final unequivocal evidence regarding the structure of the Pd(II) complex involved in the nucleophilic transfer of the allyl fragment from the palladium center to the imine could not be obtained, mechanistic insights into the events that are detrimental to the activity of the originally reported Pd(OAc)2-based catalytic systems were uncovered.

Malinakova, H. C.; Shiota, Atsushi

2012-06-29T23:59:59.000Z

406

First-principles transition-metal catalysis : efficient and accurate approaches for studying enzymatic systems  

E-Print Network (OSTI)

(cont.) We apply our approach to several paradigmatic systems: spin state splittings and structural properties of Fe2 and other small molecules as well as the addition-elimination reactions of hydrogen and methane on FeO+ ...

Kulik, Heather J

2009-01-01T23:59:59.000Z

407

CATALYSIS SCIENCE INITIATIVE: From First Principles Design to Realization of Bimetallic Catalysts for Enhanced Selectivity  

DOE Green Energy (OSTI)

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.

MAVRIKAKIS, MANOS

2007-05-03T23:59:59.000Z

408

Transition metal oxides deposited on rhodium and platinum: Surface chemistry and catalysis  

DOE Green Energy (OSTI)

The surface chemistry and catalytic reactivity of transition metal oxides deposited on Rh and Pt substrates has been examined in order to establish the role of oxide-metal interactions in influencing catalytic activity. The oxides investigated included titanium oxide (TiOx), vanadium oxide (VOx), iron oxide (FeOx), zirconium oxide (ZrOx), niobium oxide (NbOx), tantalum oxide (TaOx), and tungsten oxide (WOx). The techniques used to characterize the sample included AES, XPS, LEED, TPD, ISS, and STM. After characterization of the surface in UHV, the sample was enclosed in an atmospheric reaction cell to measure the influence of the oxide deposits on the catalytic activity of the pure metal for CO and CO{sub 2} hydrogenation. The oxide deposits were found to strongly enhance the reactivity of the Rh foil. The rates of methane formation were promoted by up to 15 fold with the maximum in rate enhancement occurring at oxide coverages of approximately 0.5 ML. TiOx TaOx, and NbOx were the most effective promoters and were stable in the highest oxidation states during both reactions (compared to VOx, WOx, and FeOx). The trend in promoter effectiveness was attributed to the direct relationship between oxidation state and Lewis acidity. Bonding at the metal oxide/metal interface between the oxygen end of adsorbed CO and the Lewis acidic oxide was postulated to facilitate C-O bond dissociation and subsequent hydrogenation. 192 refs.

Boffa, A.B. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Materials Sciences Div.

1994-07-01T23:59:59.000Z

409

Progress in nucleophilic catalysis and development of nickel-catalyzed cross-couplings of propargylic halides  

E-Print Network (OSTI)

Chapter 1 describes the development of two organocatalytic processes. The first is a 13-alkylation reaction of Michael acceptors, and represents a novel umpolung process catalyzed by N-heterocyclic carbenes. The second ...

Smith, Sean W. (Sean Wesley)

2009-01-01T23:59:59.000Z

410

ZINC CHLORIDE CATALYSIS IN COAL AND BIOMASS LIQUEFACTION AT PREPYROLYSIS TEMPERATURES  

E-Print Network (OSTI)

Howlett & A .. Gamache, Silviculture Biomass Farms; Vol. IV,a Potential Source of Biomass, Georgia Pacific Corp. MitreR.E. Inman, Silviculture Biomass Farms; Vol. 1 Summary,

Onu, Christopher O.

2013-01-01T23:59:59.000Z

411

Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis. Progress report, March 15, 1988--July 14, 1989  

Science Conference Proceedings (OSTI)

The goal of our program is to define those modes of interaction that take place between organometallic molecules and inorganic surfaces and, ultimately, to correlate various molecule-surface structures with catalytic properties.

Marks, T.J.

1990-02-01T23:59:59.000Z

412

ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis  

E-Print Network (OSTI)

or sulfated zirconia (MOx) a?ords propene and supportedium(III) catalysts, (allyl) 2 Ir-O-MOx. These catalysts were

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

413

Heterogeneous Catalysis on Atomically Dispersed Supported Metals: CO2 Reduction on Multifunctional Pd Catalysts  

Science Conference Proceedings (OSTI)

Temperature programmed reaction and scanning transmission electron microscopy experiments were applied to prove the requirement of two different catalyst functionalities for the reduction of CO2 with hydrogen on Pd/Al2O3 and Pd/MWCNT catalysts. The research described in this paper was supported by the Laboratory Directed Research and Development (LDRD) program of the Pacific Northwest National Laboratory (PNNL) and was performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL. PNNL is operated for the US DOE by Battelle Memorial Institute.

Kwak, Ja Hun; Kovarik, Libor; Szanyi, Janos

2013-11-01T23:59:59.000Z

414

Hydrogen Oxidation Catalysis by a Nickel Diphosphine Complex with Pendant tert-Butyl Amines  

DOE Green Energy (OSTI)

A bis-diphosphine nickel complex with t-butyl functionalized pendant amines [Ni(PCy2Nt-Bu2)2]2+ has been synthesized. It is a highly active electrocatalyst for the oxidation of hydrogen in the presence of base. The turn-over rate of 50 s 1 under 1.0 atm H2 at a potential of –0.77 V vs the ferrocene couple is 5 times faster than the rate reported heretofore for any other molecular H2 oxidation catalyst. 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. Computational resources were provided by the Environmental Molecular Science Laboratory (EMSL) and the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkeley National Laboratory.

Yang, Jenny Y.; Chen, Shentan; Dougherty, William G.; Kassel, W. S.; Bullock, R. Morris; DuBois, Daniel L.; Raugei, Simone; Rousseau, Roger J.; Dupuis, Michel; Rakowski DuBois, Mary

2010-11-09T23:59:59.000Z

415

Applied Catalysis A: General 226 (2002) 183192 NO reduction by urea under lean conditions  

E-Print Network (OSTI)

was tested for NOx reduction with aqueous urea solutions under oxidizing conditions. Our results show reduction of NOx in the exhaust of a lean Corresponding author. Tel.:+1-734-763-5941; fax:+1. These investigations have shown that the reduction of NOx in the exhaust of a diesel vehicle is still challenging due

Gulari, Erdogan

416

ZINC CHLORIDE CATALYSIS IN COAL AND BIOMASS LIQUEFACTION AT PREPYROLYSIS TEMPERATURES  

E-Print Network (OSTI)

of biomass utilization and conversion facilities. ChemicalChemical Structures of Biomass Components Chemical Liquefaction of Wood and l'lood Components Biomass Conversion

Onu, Christopher O.

2013-01-01T23:59:59.000Z

417

Superacid catalysis of light hydrocarbon conversion. Tenth quarterly report, January 1, 1996--March 31, 1996  

DOE Green Energy (OSTI)

Transition metal promoters markedly increase the activity of sulfated zirconia for isomerization of butane. Data presented here demonstrate the effects of the promoters zinc, iron, and manganese; none of these is as effective as the iron/manganese combination. The effects of feed impurities (olefins and/or isobutane in n-butane) are consistent with those described in the preceding quarterly report: they lead to an improvement in catalytic activity. These observations are inferred to be of practical importance; they indicate the benefit of the impurities in increasing butane conversion. The product distribution data show that reactions accompanying isomerization and disproportionation are more important with some promoters (e.g., iron) than others (e.g., zinc). The data demonstrate that the iron- and manganese-promoted catalyst can be regenerated at least sever times with negligible loss of activity (within the experimental error). To apply this catalyst or a related catalyst industrially, it seems very likely to be necessary to reduce the rate of deactivation substantially and/or to regenerate the catalyst through many cycles.

Gates, B.C. [California Univ., Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

1996-09-01T23:59:59.000Z

418

ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis  

E-Print Network (OSTI)

for Partial Oxidation of n-butane to Maleic Anhydride Y.H.catalytic activity of n-butane oxidation to maleic anhydrideconversion of methane with n-butane to give other alkanes.

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

419

Journal of Molecular Catalysis A: Chemical 166 (2001) 5972 Electronic structure of vanadyl pyrophosphate  

E-Print Network (OSTI)

in oxidation of n-butane to maleic anhydride (MA) [12­26]. The other phase of a great importance is vanadyl of butane oxidation [14]. One has to stress that the oxidation on n-butane to MA is one of the most collapse. One has also to add that oxidation of butane to MA is the only process of the selective oxidation

420

Supported organometallic complexes: Surface chemistry, spectroscopy, and catalysis. Progress report, February 1, 1991--January 31, 1992  

SciTech Connect

The long-range goal of this project is to elucidate and understand the surface chemistry and catalytic properties of well-defined, highly-reactive organometallic molecules (principally based upon abundant actinide, lanthanide, and early transition elements) adsorbed on metal oxides and halides. The nature of the adsorbed species is probed by a battery of chemical and physicochemical techniques, to understand the nature of the molecular-surface coordination chemistry and how this can give rise to extremely high catalytic activity. A complementary objective is to delineate the scope and mechanisms of the heterogeneous catalytic reactions, as well as to relate them both conceptually and functionally to model systems generated in solution.

Marks, T.J.

1992-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Strong Bond Activation with Late Transition-Metal Pincer Complexes as a Foundation for Potential Catalysis  

E-Print Network (OSTI)

Strong bond activation mediated by pincer ligated transiton-metal complexes has been the subject of intense study in recent years, due to its potential involvement in catalytic transformations. This dissertation has focused on the net heterolytic cleavage of B-H and B-B bonds across the N-Pd bond in a cationic (PNP)Pd fragment, the C-H oxidative addition to a (PNP)Ir center and the recent results on the C-H and C-O oxidative addition in reactions of aryl carboxylates with the (PNP)Rh fragment. Transition metal carbene and carbyne complexes are of great interest because of their role in a wide variety of catalytic reactions. Our work has resulted in the isolation of a rhodium(I) difluorocarbene. Reaction of the rhodium difluorocarbene complex with a silylium salt led to the C-F bond cleavage and the formation of a terminal fluorocarbyne complex. Reductive elimination is a critical step of cross coupling reactions. In order to examine the effect of the pincer ligand on the reductive elimination reactions from Rh(III), the first pi-accepting PNP ligand bearing pyrrolyl substituents was prepared and installed onto the rhodium center. Arylhalide (halide = Br, I) oxidative addition was achieved in the presence of donor ligands such as acetonitrile to form stable six-coordinate Rh(III) compounds. The C-O reductive elimination reactions in this system were also explored.

Zhu, Yanjun

2012-05-01T23:59:59.000Z

422

Heavy-Duty Emissions Control: Plasma-Facilitated vs Reformer-Assisted Lean NOx Catalysis  

DOE Green Energy (OSTI)

Progress has been made in the control of combustion processes to limit the formation of environmentally harmful species, but lean burn vehicles, such as those powered by diesel engines used for the majority of commercial trucking and off-road applications, remain a major source of nitrogen oxides (NOx) and particulate matter (PM) emissions. Tighter control of the combustion process coupled with exhaust gas recirculation has brought emissions in line with 2004 targets worldwide. Additional modifications to the engine control system, somewhat limited NOx control, and PM filters will likely allow the 2007 limits to be met for the on-highway regulations for heavy-duty engines in the United States. Concern arises when the NOx emission limit of 0.2 g/bhphr set for the year 2010 is considered.

(1)Aardahl, C; (1)Rozmiarek, R; (1)Rappe, K; (1)Mendoza, D (2)Park, P

2003-08-24T23:59:59.000Z

423

ZINC CHLORIDE CATALYSIS IN COAL AND BIOMASS LIQUEFACTION AT PREPYROLYSIS TEMPERATURES  

E-Print Network (OSTI)

pores of coal. c~n pene- Molten salts, particularly SnC1 2 ,the selection of ZnC1 2 as the molten salt catalyst for coalis very necessary. Molten salts have demonstrated catalytic

Onu, Christopher O.

2013-01-01T23:59:59.000Z

424

The Atomic AXAFS and XANES Techniques as Applied to Heterogeneous Catalysis and Electrocatalysis  

Science Conference Proceedings (OSTI)

X-Ray absorption spectroscopy (XAFS) is an attractive in situ and in operando technique. In recent years, the more conventional extended X-ray absorption fine structure (EXAFS) data analysis technique has been complemented by two newer analysis methods: the 'atomic' XAFS (AXAFS) technique, which analyzes the scattering from the absorber atom itself, and the {Delta}{mu} XANES technique, which uses a difference method to isolate the changes in the X-ray absorption near edge structure (XANES) due to adsorbates on a metal surface. With AXAFS it is possible to follow the electronic effect a support has on a metal particle; with {Delta}{mu} XANES it is possible to determine the adsorbate, the specific adsorption sites and adsorbate coverage on a metal catalyst. This unprecedented new information helps a great deal to unravel the complex kinetic mechanisms operating in working reactors or fuelcell systems. The fundamental principles and methodology for applying the AXAFS and {Delta}{mu} XANES techniques are given here, and then specific applications are summarized, including H adsorption on supported Pt in the gas phase, wateractivation at a Pt cathode and methanol oxidation at a Pt anode in an electrochemical cell, sulfur oxidation on Pt, and oxygenreduction on a Au/SnO{sub x} cathode. Finally, the future outlook for time and/or space resolved applications of these techniques is contemplated.

Ramaker, D.; Koningsberger, D

2010-01-01T23:59:59.000Z

425

ZINC CHLORIDE CATALYSIS IN COAL AND BIOMASS LIQUEFACTION AT PREPYROLYSIS TEMPERATURES  

E-Print Network (OSTI)

Bodily, Stanford Res Inst. , Coal Chemistry Workshop, 1,News, (Aug. 27, 1979). C2 Coal Processing-Gasification,L.W. Vernon, and E.L. Wilson, Coal Liquefaction by the Exxon

Onu, Christopher O.

2013-01-01T23:59:59.000Z

426

Journal of Catalysis 253 (2008) 239243 www.elsevier.com/locate/jcat  

E-Print Network (OSTI)

- drogen from paraffins, the major components of Jet A, catalytic reforming of paraffins to aromatics of the active Pt sites. However, it has been reported in catalytic reforming work that the addition of Sn

Goodman, Wayne

427

Catalysis Research of Relevance to Carbon Management: Progress, Challenges, and Opportunities  

E-Print Network (OSTI)

computers, and on-site re- chargers for battery packs used by the military. "The catalytic reforming

Goddard III, William A.

428

Superacid catalysis of light hydrocarbon conversion. Final report, August 26, 1993--August 26, 1996  

DOE Green Energy (OSTI)

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.

Gates, B.C.

1996-12-31T23:59:59.000Z

429

Superacid catalysis of light hydrocarbon conversion. Eleventh quarterly report, April 1, 1996--June 30, 1996  

DOE Green Energy (OSTI)

The new catalyst Fe- and Mn-promoted sulfated zirconia is remarkably active for the low-temperature (even room temperature) isomerization of n-butane to give isobutane in the near absence of side products. Thus this catalyst offers excellent potential for practical application in this process. The catalyst is so active that it even converts smaller alkanes, including propane and ethane. The ethane conversion is orders of magnitude slower than the butane conversion, and the prospects for practical application with ethane are apparently negligible. However, the results for ethane conversion provide strong evidence that the alkane conversions proceed (at least under some conditions) by protonation of the alkane with the catalyst; thus the catalyst is comparable to superacids, and the chemistry is analogous to that occurring in superacid solutions. This insight will be useful in further improvement of the catalyst and the potential process for butane isomerization. The catalyst is active for alkane cracking at temperatures of typically 200-300{degrees}C, and evidence, summarized here, indicates that numerous reactions of alkanes begin as the catalyst protonates the alkane reactant. The kinetics data for this family of reactions fall on a linear compensation effect plot; such data for reactions that do not proceed via such a mechanism do not fall near the line representing the compensation effect. Thus the analysis of the kinetics data provides a good diagnostic tool for understanding the fundamental chemistry of the acid-catalyzed hydrocarbon conversions.

Gates, B.C. [California Univ., Davis, CA (United States). Dept. of Chemical Engineering and Materials Science

1996-12-31T23:59:59.000Z

430

Efficient control of group I intron ribozyme catalysis by DNA constraintsw  

E-Print Network (OSTI)

., Rabin, L. B., Feinberg, M. B., Lieberman, M., Kosek, J. C., Reyes, G. R. & Weissman, I. L. (1988) Cell

Silverman, Scott K.

431

Catalysis Today 165 (2011) 29 Contents lists available at ScienceDirect  

E-Print Network (OSTI)

for competitive (Hybrid) Electric Vehicles (H)EVs, where existing nickel metal hydride (used in the Toyota Prius n f o Article history: Received 30 September 2010 Received in revised form 3 December 2010 Accepted needed. The main challenges facing the Li­air battery is the limited electrical efficiency resulting from

Thygesen, Kristian

432

Technology development for iron Fischer-Tropsch catalysis. Quarterly technical progress report, 1996  

DOE Green Energy (OSTI)

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, select 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 described.

Davis, B.H.

1996-11-01T23:59:59.000Z

433

Technology development for iron Fischer-Tropsch catalysis. [Pretreatment of catalyst in carbon monoxide  

DOE Green Energy (OSTI)

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.

Not Available

1991-01-01T23:59:59.000Z

434

ISHHC XIII International Symposium on the Relations between Homogeneous and Heterogeneous Catalysis  

E-Print Network (OSTI)

due to low solubility of syngas remain a problem for e?cientof methane to form syngas. 2 However, the structure andin the production of syngas and hydrogen from fossil and

Somorjai Ed., G.A.

2007-01-01T23:59:59.000Z

435

Catalysis of methanol-air mixture using platinum nanoparticles for microscale combustion  

Science Conference Proceedings (OSTI)

High surface area, active catalysts containing dispersed catalytic platinum nanoparticles (dp ?11.6 nm) on a cordierite substrate were fabricated and characterized using TEM, XRD, and SEM. The catalyst activity was evaluated for ...

James R. Applegate; Howard Pearlman; Smitesh D. Bakrania

2012-01-01T23:59:59.000Z

436

Final Report: Nuclear Magnetic Resonance (NMR) of Catalysis, September 1, 1993 - December 31, 1998  

DOE Green Energy (OSTI)

On going work concerns the mechanisms of methanol conversion to hydrocarbons on zeolite solid acids.

Haw, James F.

1998-12-31T23:59:59.000Z

437

Pysico-chemical properties of hydrophobic ionic liquids containing 1-octylpyridinium, 1-octyl-2-methylpyridinium or 1-octyl-4-methylpyridinium cations  

E-Print Network (OSTI)

organometallic catalysis. Chemical Reviews 2002, 102, 3667-catalysis. J. Mol. Cat. A: Chemical 2004, (12) Dai, S. ; Ju,synthesis and catalysis. Chemical Reviews 1999, 99, 2071-

Papaiconomou, Nicolas; Salminen, Justin; Lee, Jong-Min; Prausnitz, John M.

2006-01-01T23:59:59.000Z

438

SYNTHESIS OF OXYGENATED PRODUCTS FROM CARBON MONOXIDE AND HYDROGEN OVER SILICA- AND ALUMINA-SUPPORTED RUTHENIUM CATALYSTS  

E-Print Network (OSTI)

Formation Over a 1.01; Ru/A1 o Catalyst at 498K H/CO P (atm)a silica-supported Ru catalyst Fig. 2 Effect of feed flowan alumina-supported Ru catalyst Fig. 3 Effect of reaction

Kellner, C.Stephen

2013-01-01T23:59:59.000Z

439

Transition Metal Catalyzed Hydroarylation of Multiple Bonds: Exploration of Second Generation Ruthenium Catalysts and Extension to Copper Systems  

DOE Green Energy (OSTI)

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.

T. Brent Gunnoe

2011-02-17T23:59:59.000Z

440

PHYSICAL REVIEW B 84, 214110 (2011) Ordered phases in ruthenium binary alloys from high-throughput first-principles calculations  

E-Print Network (OSTI)

JAHN ´ATEK et al. PHYSICAL REVIEW B 84, 214110 (2011) and Monte Carlo simulation. Using these methods. Benarchid, N. David, J. M. Fiorani, M. Vilasi, and T. Benlaharche, Thermochim. Acta 482, 39 (2009). 50 A. A¨uller, Modell. Simul. Mater. Sci. Eng. 17, 055003 (2009). 113 A. van de Walle and G. Ceder, Rev. Mod. Phys. 74

Curtarolo, Stefano

Note: This page contains sample records for the topic "ruthenium dimer catalysis" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Temperature-programmed desorption and reaction of CO and H/sub 2/ on alumina-supported ruthenium catalyst  

DOE Green Energy (OSTI)

The temperature-programmed desorption of CO and temperature-programmed reaction of CO in flowing H/sub 2/ has been studied on a 5 wt% Ru/Al/sub 2/O/sub 3/ catalyst. CO adsorbs molecularly on Ru/Al/sub 2/O/sub 3/ at room temperature. Two distinct CO desorption peaks were observed. The activation energies of desorption were calculated to be 27 and 37 kcal/mole. Upon heating CO dissociates on Ru/Al/sub 2/O/sub 3/ at approximately 415/sup 0/K to form CO/sub 2/ and carbon. The carbon remaining on the catalyst surface enhanced the strength of adsorption of CO, probably by donating electrons to increase the degree of back bonding of the adsorbed CO. The surface carbon reacted reaidly with H/sub 2/ at 303/sup 0/C, forming CH/sub 4/ and small amounts of C/sub 2/H/sub 6/, whereas absorbed CO was inert to H/sub 2/ at this temperature. The surface carbon could easily be deactivated by heat treatment, and a very high temperature was required to remove the deactivated carbon from the catalyst surface with H/sub 2/. These results strongly suggest that carbon is a reactive intermediate and that the dissociation of CO is a necessary step in methanation and Fischer--Tropsch synthesis.

Low, G.G.

1978-08-01T23:59:59.000Z

442

TEMPERATURE-PROGRAMMED DESORPTION AND REACTION OF CO AND H2 ON ALUMINA-SUPPORTED RUTHENIUM CATALYST  

E-Print Network (OSTI)

and R. Anderson, "The Fischer-Tropsch Related Synthesis",carbide theory of Fischer and Tropsch postulated that thereactions are still (Fischer-Tropsch synthesis) from CO and

Low, Gordon Gongngai

2011-01-01T23:59:59.000Z

443

SYNTHESIS OF OXYGENATED PRODUCTS FROM CARBON MONOXIDE AND HYDROGEN OVER SILICA- AND ALUMINA-SUPPORTED RUTHENIUM CATALYSTS  

E-Print Network (OSTI)

R. B. , "The Fischer-Tropsch and Related Syntheses", Wiley,with hydrocarbons during Fischer-Tropsch synthesis over iron

Kellner, C.Stephen

2013-01-01T23:59:59.000Z

444

Directing Protons to the Dioxygen Ligand of a Ruthenium(II) Complex with Pendent Amines in the Second Coordination Sphere  

SciTech Connect

The activation and reduction of dioxygen (O2) by transition metal centers are key to a variety of biochemical and industrial processes. Efficient reduction of dioxygen to water is also important in the operation of fuel cells. These processes are typically proton-coupled electron transfer (PCET) reactions, requiring the coordinated movement of multiple protons and electrons. In biological systems, it is known that initial dioxygen bonding is facilitated by hydrogen bonding and proton delivery.

Tronic, Tristan A.; Rakowski DuBois, Mary; Kaminsky, Werner; Coggins, Michael K.; Liu, Tianbiao L.; Mayer, James M.

2011-11-11T23:59:59.000Z

445

SYNTHESIS OF OXYGENATED PRODUCTS FROM CARBON MONOXIDE AND HYDROGEN OVER SILICA- AND ALUMINA-SUPPORTED RUTHENIUM CATALYSTS  

E-Print Network (OSTI)

is consistent with the projection discussed above. Theis consistent with the projection given recently by Wilson (

Kellner, C.Stephen

2013-01-01T23:59:59.000Z

446

Isotopic separation of D.sub.2 O from H.sub.2 O using ruthenium adsorbent  

DOE Patents (OSTI)

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.

Thiel, Patricia A. (Ames, IA)

1990-04-10T23:59:59.000Z

447

--No Title--  

NLE Websites -- All DOE Office Websites (Extended Search)

CATALYSIS Home About CATALYSIS Staff Alphabetical Area of Research Research Automotive Emissions Characterization ComputationTheory Enzymatic Heterogeneous Surface Science...

448

Communication between the active sites and dimer interface of a herpesvirus protease revealed by a  

E-Print Network (OSTI)

activity assay. Although the optimal sequence from the library was Tyr (P4), Val (P3), Nle (P2), Ala (P1 6873 BIOCHEMISTRY #12;to assess protease specificity, providing an exhaustive search of potential

Craik, Charles S.

449

Infrared Spectra of C3H3 +-N2 Dimers: Identification of  

E-Print Network (OSTI)

T. Hanna & Mendi Stauffer Hanna Teresa L. Hanna & Christopher D. Hanna Carol Carpenter Hannon & W. Scott

Maier, John Paul

450

Dimeric fluorescent energy transfer dyes comprising asymmetric cyanine azole-indolenine chromophores  

DOE Patents (OSTI)

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.

Glazer, Alexander N. (Orinda, CA); Benson, Scott C. (Oakland, CA)

1998-01-01T23:59:59.000Z

451

Using Surface Plasmon Resonance to Study the Binding of Vancomycin and Its Dimer to  

E-Print Network (OSTI)

, U.; Beauregard, D. A.; Maplestone, R. A.; Williams, D. H. J. Am. Chem. Soc. 1994, 116, 4573. (5) Mackay, J. P.; Gerhard, U.; Beauregard, D. A.; Westwell, M. S.; Searle, M. S.; Williams, D. H. J. Am

Prentiss, Mara

452

The Structure of Dimeric Apolipoprotein A-IV and Its Mechanism of Self-Association  

Science Conference Proceedings (OSTI)

Apolipoproteins are key structural elements of lipoproteins and critical mediators of lipid metabolism. Their detergent-like properties allow them to emulsify lipid or exist in a soluble lipid-free form in various states of self-association. Unfortunately, these traits have hampered high-resolution structural studies needed to understand the biogenesis of cardioprotective high-density lipoproteins (HDLs). We derived a crystal structure of the core domain of human apolipoprotein (apo)A-IV, an HDL component and important mediator of lipid absorption. The structure at 2.4 {angstrom} depicts two linearly connected 4-helix bundles participating in a helix swapping arrangement that offers a clear explanation for how the protein self-associates as well as clues to the structure of its monomeric form. This also provides a logical basis for antiparallel arrangements recently described for lipid-containing particles. Furthermore, we propose a 'swinging door' model for apoA-IV lipid association.

Deng, Xiaodi; Morris, Jamie; Dressmen, James; Tubb, Matthew R.; Tso, Patrick; Jerome, W. Gray; Davidson, W. Sean; Thompson, Thomas B. (UCIN); (Vanderbilt)

2012-08-10T23:59:59.000Z

453

Structure and Functionality of a Designed p53 Dimer Timothy S. Davison1  

E-Print Network (OSTI)

tumor suppressor protein involved in transcrip- tional control of genes that regulate cell proliferation, both solubility and the resistance to thermal denaturation are substantially reduced relative-tetramer''. Analysis of the in vivo activities of full-length p53 oligomeric mutants reveals that while cell

Simons, Jack

454

Model Studies of DNA Photorepair: Reduction Potentials of Thymine and Cytosine Cyclobutane Dimers Measured by  

E-Print Network (OSTI)

, J.; Vigny, P. In Bioorganic Photochemistry; Morrison, H., Ed.; Wiley: New York, 1990; pp 1-272. (5) Smith, K. C. In The Science of Photobiology, 2nd ed.; Smith, K. C., Ed.; Plenum Press: New York, 1989,3-dimethylthymine, DMT, 1,3-bis(N4,N4-dimethylcytosin-1- yl)propane, DMC) and their corresponding cis

Yeh, Syun-Ru

455

Final technical report. Bimetallic complexes as methanol oxidation catalysts  

DOE Green Energy (OSTI)

Our work on the electrocatalyzed oxidation of methanol was initially motivated by the interest in methanol as an anodic reactant in fuel cells. The literature on electrochemical oxidation of alcohols can be roughly grouped into two sets: fuel cell studies and inorganic chemistry studies. Work on fuel cells primarily focuses on surface-catalyzed oxidation at bulk metal anodes, usually Pt or Pt/Ru alloys. In the surface science/electrochemistry approach to these studies, single molecule catalysts are generally not considered. In contrast, the inorganic community investigates the electrooxidation of alcohols in homogeneous systems. Ruthenium complexes have been the most common catalysts in these studies. The alcohol substrates are typically either secondary alcohols (e.g., isopropanol) such that the reaction stops after 2 e{sup -} oxidation to the aldehyde and 4 e{sup -} oxidation to the carboxylic acid can be observed. Methanol, which can also undergo 6 e{sup -} oxidation to CO{sub 2}, rarely appears in the homogeneous catalysis studies. Surface studies have shown that two types of metal centers with different functions result in more effective catalysts than a single metal; however, application of this concept to homogeneous systems has not been demonstrated. The major thrust of the work is to apply this insight from the surface studies to homogeneous catalysis. Even though homogeneous systems would not be appropriate models for active sites on Pt/Ru anodes, it is possible that heterobimetallic catalysts could also utilize two metal centers for different roles. Starting from that perspective, this work involves the preparation and investigation of heterobinuclear catalysts for the electrochemical oxidation of methanol.

McElwee-White, Lisa

2002-01-21T23:59:59.000Z

456

A Facile Synthesis of MPd (M=Co, Cu) Nanoparticles and Their Catalysis for Formic Acid Oxidation  

SciTech Connect

Monodisperse CoPd nanoparticles (NPs) were synthesized and studied for catalytic formic acid (HCOOH) oxidation (FAO). The NPs were prepared by coreduction of Co(acac)2 (acac = acetylacetonate) and PdBr2 at 260 C in oleylamine and trioctylphosphine, and their sizes (5-12 nm) and compositions (Co10Pd90 to Co60Pd40) were controlled by heating ramp rate, metal salt concentration, or metal molar ratios. The 8 nm CoPd NPs were activated for HCOOH oxidation by a simple ethanol wash. In 0.1 M HClO4 and 2 M HCOOH solution, their catalytic activities followed the trend of Co50Pd50 > Co60Pd40 > Co10Pd90 > Pd. The Co50Pd50 NPs had an oxidation peak at 0.4 V with a peak current density of 774 A/gPd. As a comparison, commercial Pd catalysts showed an oxidation peak at 0.75 V with peak current density of only 254 A/gPd. The synthesis procedure could also be extended to prepare CuPd NPs when Co(acac)2 was replaced by Cu(ac)2 (ac = acetate) in an otherwise identical condition. The CuPd NPs were less active catalysts than CoPd or even Pd for FAO in HClO4 solution. The synthesis provides a general approach to Pd-based bimetallic NPs and will enable further investigation of Pd-based alloy NPs for electro-oxidation and other catalytic reactions.

Mazumder, Vismadeb [Brown University; Chi, Miaofang [ORNL; Mankin, Max [Brown University; Liu, Yi [Brown University; Metin, Onder [Ataturk University; Sun, Daohua [Xiamen University, China; More, Karren Leslie [ORNL; Sun, Shouheng [Brown University

2012-01-01T23:59:59.000Z

457

Journal of Molecular Catalysis A: Chemical 163 (2000) 918 Methane activation on Ni and Ru model catalysts  

E-Print Network (OSTI)

these intermediates play in important methane reactions such as steam reforming, partial oxidation and homologation, methane activation represents a great challenge to researchers all over the world. Currently steam reforming of methane represents the primary route for methane conversion [8,9]. This highly endothermic

Goodman, Wayne

458

A Phenomenological Study of the Metal-Oxide Interface: The Role of Catalysis in Hydrogen Production from Renewable Resources  

SciTech Connect

The truth about Cats: The metal-oxide interface of a Pd-Rh/CeO{sub 2} catalyst was studied in the context of developing active, selective and durable solid catalytic materials for the production of hydrogen from renewables. The presence of a stable contact between finely dispersed transition-metal clusters (Pd and Rh) on the nanoparticles of the CeO{sub 2} support leads to a highly active and stable catalyst for the steam reforming of ethanol.

Idriss, H.; Llorca, J; Chan, S; Blackford, M; Pas, S; Hill, A; Alamgir, F; Rettew, R; Petersburg, C; Barteau, M

2008-01-01T23:59:59.000Z

459

Parametric Gasification of Oak and Pine Feedstocks Using the TCPDU and Slipstream Water-Gas Shift Catalysis  

DOE Green Energy (OSTI)

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.

Hrdlicka, J.; Feik, C.; Carpenter, D.; Pomeroy, M.

2008-12-01T23:59:59.000Z

460

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

Science Conference Proceedings (OSTI)

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.

Akio; Ishikawa; Manuel Ojeda; Nan Yao; Enrique Iglesia

2006-09-30T23:59:59.000Z

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461

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

SciTech Connect

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.

Enrique Iglesia

2004-09-30T23:59:59.000Z

462

Catalysis Letters Vol. 77, No. 4, 2001 197 Effects of Zn, Cu, and K promoters on the structure  

E-Print Network (OSTI)

and industry, ExxonMobil announced a $600 million program [10-12]. However, the use of Fischer Tropsch the economics, we can help bridge the gap between current fuels and biofuels by using Fischer Tropsch technology is purified, the syngas consisting of H2 and CO follows the Fischer-Tropsch synthesis to produce liquid

Iglesia, Enrique

463

Applied Catalysis A: General 219 (2001) 215222 Structural analysis of unpromoted Fe-based FischerTropsch  

E-Print Network (OSTI)

of synthesis gas, Fischer-Tropsch synthesis, and dehydrogenation of C2- C4 alkanes. The work is carried out. Rytter, A. Holmen, Deactivation of cobalt based Fischer-Tropsch catalysts: A review, Catal. Today, 154-oil upgrading, syngas cleaning and composition adjustment, residual hydrocarbon reforming and Fischer-Tropsch

Iglesia, Enrique

464

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

DOE Green Energy (OSTI)

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.

Jian Xu; Enrique Iglesia

2004-03-31T23:59:59.000Z

465

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

SciTech Connect

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{

Enrique Iglesia; Akio Ishikawa; Manual Ojeda; Nan Yao

2007-09-30T23:59:59.000Z

466

Conversion of methane to higher hydrocarbons (Biomimetic catalysis of the conversion of methane to methanol). Final report  

DOE Green Energy (OSTI)

In addition to inorganic catalysts that react with methane, it is well-known that a select group of aerobic soil/water bacteria called methanotrophs can efficiently and selectively utilize methane as the sole source of their energy and carbon for cellular growth. The first reaction in this metabolic pathway is catalyzed by the enzyme methane monooxygenase (MMO) forming methanol. Methanol is a technology important product from this partial oxidation of methane since it can be easily converted to liquid hydrocarbon transportation fuels (gasoline), used directly as a liquid fuel or fuel additive itself, or serve as a feedstock for chemicals production. This naturally occurring biocatalyst (MMO) is accomplishing a technologically important transformation (methane directly to methanol) for which there is currently no analogous chemical (non-biological) process. The authors approach has been to use the biocatalyst, MMO, as the initial focus in the development of discrete chemical catalysts (biomimetic complexes) for methane conversion. The advantage of this approach is that it exploits a biocatalytic system already performing a desired transformation of methane. In addition, this approach generated needed new experimental information on catalyst structure and function in order to develop new catalysts rationally and systematically. The first task is a comparative mechanistic, biochemical, and spectroscopic investigation of MMO enzyme systems. This work was directed at developing a description of the structure and function of the catalytically active sites in sufficient detail to generate a biomimetic material. The second task involves the synthesis, characterization, and chemical reactions of discrete complexes that mimic the enzymatic active site. These complexes were synthesized based on their best current understanding of the MMO active site structure.

Watkins, B.E.; Taylor, R.T.; Satcher, J.H. [and others

1993-09-01T23:59:59.000Z

467

Studies of metal: semiconductor interfaces in catalysis and energy conversion. Annual report, June 15, 1980-June 14, 1981  

DOE Green Energy (OSTI)

It was shown that CO hydrogenation reactions can be performed reproducibly on a small area well characterized Ni (111) single crystal using an isolation cell technique. The activation energy for methane production (24.7 kcal/mole) and other hydrocarbon product distribution are in excellent agreement with the literature. It was demonstrated that Ni dispersed onto TiO/sub 2/ (100) acquires a negative charge and that the Ni/TiO/sub 2/ (100) exhibits a methanation activity at least 4 times that of Ni(111) with about the same activation energy. The Ni/TiO/sub 2/ also produces more higher hydrocarbons than Ni(111). The photochemical activity of Pt/SrTiO/sub 3/ in both aqueous solutions and in gas phase water was examined. The activity in aqueous solutions under different conditions of pH and Pt coverage can be explained by band bending effects. A low hydrogen yield was observed in the presence of water vapor; this was attributed to a slow photo-regeneration of active surface Ti/sup 3 +/. Preliminary high resolution electron energy loss studies on TiO/sub 2/ (100) showed strong surface phonon bands extending to 3000 cm/sup -1/.

Chung, Y W

1981-02-01T23:59:59.000Z

468

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

DOE Green Energy (OSTI)

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 wi