National Library of Energy BETA

Sample records for homogeneous catalysis heterogeneous

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

    SciTech Connect (OSTI)

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

    2009-10-15

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

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

    SciTech Connect (OSTI)

    Somorjai , G.A.

    2007-06-11

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

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

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

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

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

    SciTech Connect (OSTI)

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

    2011-11-23

    Determining the true, kinetically dominant catalytically active species, in the classic benzene hydrogenation system pioneered by Maitlis and co-workers 34 years ago starting with [RhCp*Cl2]2 (Cp* = [{eta}5-C5(CH3)5]), has proven to be one of the most challenging case studies in the quest to distinguish single-metal-based 'homogeneous' from polymetallic, 'heterogeneous' catalysis. The reason, this study will show, is the previous failure to use the proper combination of (i) operando spectroscopy to determine the dominant form(s) of the precatalyst's mass under catalysis (i.e., operating) conditions, plus then and crucially also (ii) the previous lack of the necessary kinetic studies, catalysis being a 'wholly kinetic phenomenon' as J. Halpern long ago noted. An important contribution from this study will be to reveal the power of quantitiative kinetic poisoning experiments for distinguishing single-metal, or in this case subnanometer Rh4 cluster-based catalysis from larger, polymetallic Rh(0)n nanoparticle catalysis, at least under favorable conditions. The combined operando-XAFS (X-ray absorption fine structure) spectroscopy and kinetic evidences provide a compelling case for Rh4-based, with average stoichiometry 'Rh4Cp*2.4Cl4Hc', benzene hydrogenation catalysis in 2-propanol with added Et3N and at 100 C and 50 atm initial H2 pressure. The results also reveal, however, that if even ca. 1.4% of the total soluble Rh(0)n had formed nanoparticles, then those Rh(0)n nanoparticles would have been able to account for all the observed benzene hydrogenation catalytic rate (using commercial, ca. 2 nm, polyethyleneglycol-dodecylether hydrosol stabilized Rh(0)n nanoparticles as a model system). The results 'especially the poisoning methodology developed and employed' are of significant, broader interest since determining the nature of the true catalyst continues to be a central, often vexing issue in any and all catalytic reactions. The results are also of fundamental

  5. Reaction Selectivity in Heterogeneous Catalysis

    SciTech Connect (OSTI)

    Somorjai, Gabor A.; Kliewer, Christopher J.

    2009-02-02

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

  6. Heterogeneous Catalysis and Surface Science - JCAP

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

    Heterogeneous Catalysis and Surface Science / Part I: Surface Science in JCAP Laboratories Heterogeneous Catalysis and Surface Science research in JCAP focuses on the basic understanding of the relationships among the structure, composition, and reactivity of electrocatalysts. Knowledge gained from surface science experimentation can be implemented toward the discovery of better heterogeneous catalysts for solar-fuel production from carbon dioxide and water. REFERENCE Soriaga, M. P. et al.

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

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

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

  8. Heterogeneous Catalysis for Thermochemical Conversion | Bioenergy | NREL

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

    Heterogeneous Catalysis for Thermochemical Conversion Our mission is to transform thermal biomass deconstruction products (syngas and pyrolysis oil) into the fuels and chemicals that keep society moving forward. Illustration of a stacked series of red and grey spheres in a square shape, where red spheres represent oxygen and grey spheres represent titanium) with a stack of orange and small white spheres, where orange spheres represent platinum and white spheres represent hydrogen, in a square

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

    Office of Science (SC) Website

    Heterogeneous Catalysis - J. K. Norskov Homogeneous and Single-Site Heterogeneous Catalysis - Tobin Marks Thursday, May 16, 2002 - Breakout Summary Reports Catalysts Design Driven ...

  10. Advanced Electronic Structure Methods for Heterogeneous Catalysis and

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

    Separation of Heavy Metals | Argonne Leadership Computing Facility The research team is also using GAMESS in an INCITE project entitled State-of-the-Art Simulations of Liquid Phenomena. As part of the INCITE work, they predicted that the turning point between surface and interior solvation in a nitrate ion occurs at a cluster size of around 64 water molecules. Spencer Pruitt, Argonne National Laboratory Advanced Electronic Structure Methods for Heterogeneous Catalysis and Separation of Heavy

  11. Molecular-Level Design of Heterogeneous Chiral Catalysis

    SciTech Connect (OSTI)

    Francisco Zaera

    2012-03-21

    The following is a proposal to continue our multi-institutional research on heterogeneous chiral catalysis. Our team combines the use of surface-sensitive analytical techniques for the characterization of model systems with quantum and statistical mechanical calculations to interpret experimental data and guide the design of future research. Our investigation focuses on the interrelation among the three main mechanisms by which enantioselectivity can be bestowed to heterogeneous catalysts, namely: (1) by templating chirality via the adsorption of chiral supramolecular assemblies, (2) by using chiral modifiers capable of forming chiral complexes with the reactant and force enantioselective surface reactions, and (3) by forming naturally chiral surfaces using imprinting chiral agents. Individually, the members of our team are leaders in these various aspects of chiral catalysis, but the present program provides the vehicle to generate and exploit the synergies necessary to address the problem in a comprehensive manner. Our initial work has advanced the methodology needed for these studies, including an enantioselective titration procedure to identify surface chiral sites, infrared spectroscopy in situ at the interface between gases or liquids and solids to mimic realistic catalytic conditions, and DFT and Monte Carlo algorithms to simulate and understand chirality on surfaces. The next step, to be funded by the monies requested in this proposal, is to apply those methods to specific problems in chiral catalysis, including the identification of the requirements for the formation of supramolecular surface structures with enantioselective behavior, the search for better molecules to probe the chiral nature of the modified surfaces, the exploration of the transition from supramolecular to one-to-one chiral modification, the correlation of the adsorption characteristics of one-to-one chiral modifiers with their physical properties, in particular with their configuration

  12. Theoretical approach to heterogeneous catalysis using large finite crystals

    SciTech Connect (OSTI)

    Salem, L.

    1985-12-19

    A theoretical-approach is described for heterogeneous catalysis using large finite crystals and an exactly soluble model. First, reviews of some themes which are well-known to physicists but need a translation into chemical language: wave vectors, the tight-binding model, and energy bands. Next a description of the finite simple cubic crystal and its analytical wave functions and energies in the Hueckel scheme is given. Also the analytical Hueckel wave functions for a finite face-centered cubic (FCC) crystal cut along square, (100)-type faces is described. Then the calculation of the perturbation interaction energy between H/sub 2/ and large finite (simple cubic or FCC) crystals of Ni atoms, having up to 13,824 atoms is described. The interaction energy is shown to be independent of crystal size, whatever the position of attack of the H/sub 2/ molecule. 28 references, 9 figures, 8 tables.

  13. Application of solid ash based catalysts in heterogeneous catalysis

    SciTech Connect (OSTI)

    Shaobin Wang

    2008-10-01

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

  14. Cryogenic homogenization and sampling of heterogeneous multi-phase feedstock

    DOE Patents [OSTI]

    Doyle, Glenn Michael (Lakewood, CO); Ideker, Virgene Linda (Arvada, CO); Siegwarth, James David (Boulder, CO)

    2002-01-01

    An apparatus and process for producing a homogeneous analytical sample from a heterogenous feedstock by: providing the mixed feedstock, reducing the temperature of the feedstock to a temperature below a critical temperature, reducing the size of the feedstock components, blending the reduced size feedstock to form a homogeneous mixture; and obtaining a representative sample of the homogeneous mixture. The size reduction and blending steps are performed at temperatures below the critical temperature in order to retain organic compounds in the form of solvents, oils, or liquids that may be adsorbed onto or absorbed into the solid components of the mixture, while also improving the efficiency of the size reduction. Preferably, the critical temperature is less than 77 K (-196.degree. C.). Further, with the process of this invention the representative sample may be maintained below the critical temperature until being analyzed.

  15. Highly Dispersed Pseudo-Homogeneous and Heterogeneous Catalysts Synthesized via Inverse Micelle Solutions for the Liquefaction of Coal

    SciTech Connect (OSTI)

    Hampden-Smith, M.; Kawola, J.S.; Martino, A.; Sault, A.G.; Yamanaka, S.A.

    1999-01-05

    The mission of this project was to use inverse micelle solutions to synthesize nanometer sized metal particles and test the particles as catalysts in the liquefaction of coal and other related reactions. The initial focus of the project was the synthesis of iron based materials in pseudo-homogeneous form. The frost three chapters discuss the synthesis, characterization, and catalyst testing in coal liquefaction and model coal liquefaction reactions of iron based pseudo-homogeneous materials. Later, we became interested in highly dispersed catalysts for coprocessing of coal and plastic waste. Bifunctional catalysts . to hydrogenate the coal and depolymerize the plastic waste are ideal. We began studying, based on our previously devised synthesis strategies, the synthesis of heterogeneous catalysts with a bifunctional nature. In chapter 4, we discuss the fundamental principles in heterogeneous catalysis synthesis with inverse micelle solutions. In chapter 5, we extend the synthesis of chapter 4 to practical systems and use the materials in catalyst testing. Finally in chapter 6, we return to iron and coal liquefaction now studied with the heterogeneous catalysts.

  16. DOE Laboratory Catalysis Research Symposium - Abstracts

    SciTech Connect (OSTI)

    Dunham, T.

    1999-02-01

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

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

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

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

    2016-01-28

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

  18. Plasma-assisted heterogeneous catalysis for NOx reduction in lean-burn engine exhaust

    SciTech Connect (OSTI)

    Penetrante, B.M.; Hsaio, M.C.; Merritt, B.T.; Vogtlin, G.E.; Wan, C.Z.; Rice, G.W.; Voss, K.E.

    1997-12-31

    This paper discusses the combination of a plasma with a catalyst to improve the reduction of NO{sub x} under lean-burn conditions. The authors have been investigating the effects of a plasma on the NO{sub x} reduction activity and temperature operating window of various catalytic materials. One of the goals is to develop a fundamental understanding of the interaction between the gas-phase plasma chemistry and the heterogeneous chemistry on the catalyst surface. The authors have observed that plasma assisted heterogeneous catalysis can facilitate NO{sub x} reduction under conditions that normally make it difficult for either the plasma or the catalyst to function by itself. By systematically varying the plasma electrode and catalyst configuration, they have been able to elucidate the process by which the plasma chemistry affects the chemical reduction of NO{sub x} on the catalyst surface. They have discovered that the main effect of the plasma is to induce the gas-phase oxidation of NO to NO{sub 21}. The reduction of NO{sub x} to N{sub 2} is then accomplished by heterogeneous reaction of O with activated hydrocarbons on the catalyst surface. The use of a plasma opens the opportunity for a new class of catalysts that are potentially more durable, more active, more selective and more sulfur-tolerant compared to conventional lean-NO{sub x} catalysts.

  19. A numerical homogenization method for heterogeneous, anisotropic elastic media based on multiscale theory

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

    Gao, Kai; Chung, Eric T.; Gibson, Richard L.; Fu, Shubin; Efendiev, Yalchin

    2015-06-05

    The development of reliable methods for upscaling fine scale models of elastic media has long been an important topic for rock physics and applied seismology. Several effective medium theories have been developed to provide elastic parameters for materials such as finely layered media or randomly oriented or aligned fractures. In such cases, the analytic solutions for upscaled properties can be used for accurate prediction of wave propagation. However, such theories cannot be applied directly to homogenize elastic media with more complex, arbitrary spatial heterogeneity. We therefore propose a numerical homogenization algorithm based on multiscale finite element methods for simulating elasticmore » wave propagation in heterogeneous, anisotropic elastic media. Specifically, our method used multiscale basis functions obtained from a local linear elasticity problem with appropriately defined boundary conditions. Homogenized, effective medium parameters were then computed using these basis functions, and the approach applied a numerical discretization that is similar to the rotated staggered-grid finite difference scheme. Comparisons of the results from our method and from conventional, analytical approaches for finely layered media showed that the homogenization reliably estimated elastic parameters for this simple geometry. Additional tests examined anisotropic models with arbitrary spatial heterogeneity where the average size of the heterogeneities ranged from several centimeters to several meters, and the ratio between the dominant wavelength and the average size of the arbitrary heterogeneities ranged from 10 to 100. Comparisons to finite-difference simulations proved that the numerical homogenization was equally accurate for these complex cases.« less

  20. A numerical homogenization method for heterogeneous, anisotropic elastic media based on multiscale theory

    SciTech Connect (OSTI)

    Gao, Kai; Chung, Eric T.; Gibson, Richard L.; Fu, Shubin; Efendiev, Yalchin

    2015-06-05

    The development of reliable methods for upscaling fine scale models of elastic media has long been an important topic for rock physics and applied seismology. Several effective medium theories have been developed to provide elastic parameters for materials such as finely layered media or randomly oriented or aligned fractures. In such cases, the analytic solutions for upscaled properties can be used for accurate prediction of wave propagation. However, such theories cannot be applied directly to homogenize elastic media with more complex, arbitrary spatial heterogeneity. We therefore propose a numerical homogenization algorithm based on multiscale finite element methods for simulating elastic wave propagation in heterogeneous, anisotropic elastic media. Specifically, our method used multiscale basis functions obtained from a local linear elasticity problem with appropriately defined boundary conditions. Homogenized, effective medium parameters were then computed using these basis functions, and the approach applied a numerical discretization that is similar to the rotated staggered-grid finite difference scheme. Comparisons of the results from our method and from conventional, analytical approaches for finely layered media showed that the homogenization reliably estimated elastic parameters for this simple geometry. Additional tests examined anisotropic models with arbitrary spatial heterogeneity where the average size of the heterogeneities ranged from several centimeters to several meters, and the ratio between the dominant wavelength and the average size of the arbitrary heterogeneities ranged from 10 to 100. Comparisons to finite-difference simulations proved that the numerical homogenization was equally accurate for these complex cases.

  1. Surface functionalization of metal?organic polyhedron for homogeneous cyclopropanation catalysis

    SciTech Connect (OSTI)

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

    2012-03-13

    A super-paddlewheel (comprised of two paddlewheels) metal-organic polyhedron (MOP) containing surface hydroxyl groups was synthesized and characterized. Condensation reactions with linear alkyl anhydrides lead to new MOPs with enhanced solubility. As a result, the surface-modified MOP 4 was demonstrated as a homogeneous Lewis-acid catalyst.

  2. Workshop: Synchrotron Applications in Chemical Catalysis | Stanford

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

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

  3. Impact of heterogeneous ice nuclei on homogeneous freezing events in cirrus clouds

    SciTech Connect (OSTI)

    Spichtinger, Peter; Cziczo, Daniel J.

    2010-07-29

    The influence of initial heterogeneous nucleation on subsequent homogeneous nucleation events in cirrus clouds is investigated using a box model which includes the explicit impact of aerosols on the nucleation of ice crystals and sedimentation. Different effects are discussed, namely the impact of external mixtures of heterogeneous ice nuclei and the influence of size-dependent freezing thresholds. Several idealized experiments are carried out, which show that the treatment of external mixtures of ice nuclei can strongly change later homogeneous nucleation events (i.e., the ice crystal number densities) in different matters. The use of size-dependent freezing thresholds can also change the cloud prop erties when compared to more simple parameterizations. This size effect is most important for large IN concentrations. Based upon these findings, recommendations for future modeling and measurement efforts are presented.

  4. The performance of 3500 MWth homogeneous and heterogeneous metal fueled core designs

    SciTech Connect (OSTI)

    Turski, R.; Yang, Shi-tien

    1987-11-01

    Performance parameters are calculated for a representative 3500 MWth homogeneous and a heterogeneous metal fueled reactor design. The equilibrium cycle neutronic characteristics, safety coefficients, control system requirements, and control rod worths are evaluated. The thermal-hydraulic characteristics for both configurations are also compared. The heavy metal fuel loading requirements and neutronic performance characteristics are also evaluated for the uranium startup option. 14 refs., 14 figs., 20 tabs.

  5. An Experimental Investigation of Foam Flow in Homogeneous and Heterogeneous Porous Media, SUPRI TR-112

    SciTech Connect (OSTI)

    Apaydin, Osman G.; Bertin, Henri; Castanier, Louis M.; Kovscek, Anthony R.

    1999-08-09

    Foam is used to reduce the high mobility of gas-drive fluids and improve the contact between oil and these injected fluids. We require a better understanding of the effect of surfactant concentration on foam flow in porous media. Besides this, the literature on foam flow and transport in heterogeneous systems is sparse although the field situation is primarily heterogeneous and multidimensional. In this study, foam flow experiments were conducted first in homogeneous sand packs to investigate the effect of surfactant concentration on foam flow and then a heterogeneous experimental setup was prepared to observe heterogeneity and multidimensional flow effects on foam propagation. The homogeneous core experiments were conducted in a cylindrical aluminum core holder that was packed with a uniform Ottawa sand. Sand permeability is about 7.0 Darcy. The experiments were interpreted in terms of evolution of in-situ water saturation as a function of time by the usage of CT scanner, cumulative water, and pressure drop across the core. At very low surfactant concentration, no significant benefit was observed. But when stable foam generation started sweep efficiency (water recovery), breakthrough time, and pressure drop increased as surfactant concentration increased.

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

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

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

    2016-04-21

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

  7. Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

    SciTech Connect (OSTI)

    J. Helble; Clara Smith; David Miller

    2009-08-31

    The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.

  8. Lattice Boltzmann simulation of immiscible fluid displacement in porous media: Homogeneous versus heterogeneous pore network

    SciTech Connect (OSTI)

    Liu, Haihu; Zhang, Yonghao; Valocchi, Albert J.

    2015-05-15

    Injection of anthropogenic carbon dioxide (CO{sub 2}) into geological formations is a promising approach to reduce greenhouse gas emissions into the atmosphere. Predicting the amount of CO{sub 2} that can be captured and its long-term storage stability in subsurface requires a fundamental understanding of multiphase displacement phenomena at the pore scale. In this paper, the lattice Boltzmann method is employed to simulate the immiscible displacement of a wetting fluid by a non-wetting one in two microfluidic flow cells, one with a homogeneous pore network and the other with a randomly heterogeneous pore network. We have identified three different displacement patterns, namely, stable displacement, capillary fingering, and viscous fingering, all of which are strongly dependent upon the capillary number (Ca), viscosity ratio (M), and the media heterogeneity. The non-wetting fluid saturation (S{sub nw}) is found to increase nearly linearly with logCa for each constant M. Increasing M (viscosity ratio of non-wetting fluid to wetting fluid) or decreasing the media heterogeneity can enhance the stability of the displacement process, resulting in an increase in S{sub nw}. In either pore networks, the specific interfacial length is linearly proportional to S{sub nw} during drainage with equal proportionality constant for all cases excluding those revealing considerable viscous fingering. Our numerical results confirm the previous experimental finding that the steady state specific interfacial length exhibits a linear dependence on S{sub nw} for either favorable (M ? 1) or unfavorable (M < 1) displacement, and the slope is slightly higher for the unfavorable displacement.

  9. Comparison of Homogeneous and Heterogeneous CFD Fuel Models for Phase I of the IAEA CRP on HTR Uncertainties Benchmark

    SciTech Connect (OSTI)

    Gerhard Strydom; Su-Jong Yoon

    2014-04-01

    Computational Fluid Dynamics (CFD) evaluation of homogeneous and heterogeneous fuel models was performed as part of the Phase I calculations of the International Atomic Energy Agency (IAEA) Coordinate Research Program (CRP) on High Temperature Reactor (HTR) Uncertainties in Modeling (UAM). This study was focused on the nominal localized stand-alone fuel thermal response, as defined in Ex. I-3 and I-4 of the HTR UAM. The aim of the stand-alone thermal unit-cell simulation is to isolate the effect of material and boundary input uncertainties on a very simplified problem, before propagation of these uncertainties are performed in subsequent coupled neutronics/thermal fluids phases on the benchmark. In many of the previous studies for high temperature gas cooled reactors, the volume-averaged homogeneous mixture model of a single fuel compact has been applied. In the homogeneous model, the Tristructural Isotropic (TRISO) fuel particles in the fuel compact were not modeled directly and an effective thermal conductivity was employed for the thermo-physical properties of the fuel compact. On the contrary, in the heterogeneous model, the uranium carbide (UCO), inner and outer pyrolytic carbon (IPyC/OPyC) and silicon carbide (SiC) layers of the TRISO fuel particles are explicitly modeled. The fuel compact is modeled as a heterogeneous mixture of TRISO fuel kernels embedded in H-451 matrix graphite. In this study, a steady-state and transient CFD simulations were performed with both homogeneous and heterogeneous models to compare the thermal characteristics. The nominal values of the input parameters are used for this CFD analysis. In a future study, the effects of input uncertainties in the material properties and boundary parameters will be investigated and reported.

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

    SciTech Connect (OSTI)

    Rodriguez,J.A.; Liu, P.

    2008-10-01

    Traditionally, knowledge in heterogeneous catalysis has come through empirical research. Nowadays, there is a clear interest to change this since millions of dollars in products are generated every year in the chemical and petrochemical industries through catalytic processes. To obtain a fundamental knowledge of the factors that determine the activity of heterogeneous catalysts is a challenge for modern science since many of these systems are very complex in nature. In principle, when a molecule adsorbs on the surface of a heterogeneous catalyst, it can interact with a large number of bonding sites. It is known that the chemical properties of these bonding sites depend strongly on the chemical environment around them. Thus, there can be big variations in chemical reactivity when going from one region to another in the surface of a heterogeneous catalyst. A main objective is to understand how the structural and electronic properties of a surface affect the energetics for adsorption processes and the paths for dissociation and chemical reactions. In recent years, advances in instrumentation and experimental procedures have allowed a large series of detailed works on the surface chemistry of heterogeneous catalysts. In many cases, these experimental studies have shown interesting and unique phenomena. Theory is needed to unravel the basic interactions behind these phenomena and to provide a general framework for the interpretation of experimental results. Ideally, theoretical calculations based on density-functional theory have evolved to the point that one should be able to predict patterns in the activity of catalytic surfaces. As in the case of experimental techniques, no single theoretical approach is able to address the large diversity of phenomena occurring on a catalyst. Catalytic surfaces are usually modeled using either a finite cluster or a two-dimensionally periodic slab. Many articles have been published comparing the results of these two approaches. An

  11. Fabrication of Carbon-Platinum Interdigitated Array Electrodes and Their Application for Investigating Homogeneous Hydrogen Evolution Catalysis

    SciTech Connect (OSTI)

    Liu, Fei; Divan, Ralu; Parkinson, Bruce A.

    2015-06-29

    Carbon interdigitated array (IDA) electrodes have been applied to study the homogeneous hydrogen evolution electrocatalyst [Ni(PPh2NBn2)2]2+ (where PPh2NBn2 is 1,5-dibenzyl-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane). The existence of reaction intermediates in the catalytic cycle is inferred from the electrochemical behavior of a glassy carbon disk electrodes and carbon IDA electrodes. The currents on IDA electrodes for an EC’ (electron transfer reaction followed by a catalytic reaction) mechanism are derived from the number of redox cycles and the contribution of non-catalytic currents. The catalytic reaction rate constant was then extracted from the IDA current equations. Applying the IDA current and kinetic equations to the electrochemical response of the [Ni(PPh2NBn2)2]2+ catalyst yielded a rate constant of 0.10 s-1 for the hydrogen evolution reaction that agrees with the literature value. The quantitative analysis of IDA cyclic voltammetry can be used as a simple and straightforward method for determining rate constants in other catalytic systems. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for DOE. Use of the Center for Nanoscale Materials was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

  12. 2012 Catalysis Lectures

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

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

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

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

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

  14. Catalysis Workshop

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

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

  15. Experimental and numerical analysis of parallel reactant flow and transverse mixing with mineral precipitation in homogeneous and heterogeneous porous media

    SciTech Connect (OSTI)

    Fox, Don T.; Guo, Luanjing; Fujita, Yoshiko; Huang, Hai; Redden, George

    2015-12-17

    Formation of mineral precipitates in the mixing interface between two reactant solutions flowing in parallel in porous media is governed by reactant mixing by diffusion and dispersion and is coupled to changes in porosity/permeability due to precipitation. The spatial and temporal distribution of mixing-dependent precipitation of barium sulfate in porous media was investigated with side-by-side injection of barium chloride and sodium sulfate solutions in thin rectangular flow cells packed with quartz sand. The results for homogeneous sand beds were compared to beds with higher or lower permeability inclusions positioned in the path of the mixing zone. In the homogeneous and high permeability inclusion experiments, BaSO4 precipitate (barite) formed in a narrow deposit along the length and in the center of the solution–solution mixing zone even though dispersion was enhanced within, and downstream of, the high permeability inclusion. In the low permeability inclusion experiment, the deflected BaSO4 precipitation zone broadened around one side and downstream of the inclusion and was observed to migrate laterally toward the sulfate solution. A continuum-scale fully coupled reactive transport model that simultaneously solves the nonlinear governing equations for fluid flow, transport of reactants and geochemical reactions was used to simulate the experiments and provide insight into mechanisms underlying the experimental observations. Lastly, migration of the precipitation zone in the low permeability inclusion experiment could be explained by the coupling effects among fluid flow, reactant transport and localized mineral precipitation reaction.

  16. Experimental and numerical analysis of parallel reactant flow and transverse mixing with mineral precipitation in homogeneous and heterogeneous porous media

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

    Fox, Don T.; Guo, Luanjing; Fujita, Yoshiko; Huang, Hai; Redden, George

    2015-12-17

    Formation of mineral precipitates in the mixing interface between two reactant solutions flowing in parallel in porous media is governed by reactant mixing by diffusion and dispersion and is coupled to changes in porosity/permeability due to precipitation. The spatial and temporal distribution of mixing-dependent precipitation of barium sulfate in porous media was investigated with side-by-side injection of barium chloride and sodium sulfate solutions in thin rectangular flow cells packed with quartz sand. The results for homogeneous sand beds were compared to beds with higher or lower permeability inclusions positioned in the path of the mixing zone. In the homogeneous andmore » high permeability inclusion experiments, BaSO4 precipitate (barite) formed in a narrow deposit along the length and in the center of the solution–solution mixing zone even though dispersion was enhanced within, and downstream of, the high permeability inclusion. In the low permeability inclusion experiment, the deflected BaSO4 precipitation zone broadened around one side and downstream of the inclusion and was observed to migrate laterally toward the sulfate solution. A continuum-scale fully coupled reactive transport model that simultaneously solves the nonlinear governing equations for fluid flow, transport of reactants and geochemical reactions was used to simulate the experiments and provide insight into mechanisms underlying the experimental observations. Lastly, migration of the precipitation zone in the low permeability inclusion experiment could be explained by the coupling effects among fluid flow, reactant transport and localized mineral precipitation reaction.« less

  17. In situ measurements of a homogeneous to heterogeneous transition in the plastic response of ion-irradiated Ni microspecimens

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

    Zhao, Xinyu; Strickland, Daniel J.; Derlet, Peter M.; He, Mo-rigen; Cheng, You -Jung; Pu, Jue; Stanford Univ., Stanford, CA; Hattar, Khalid; Gianola, Daniel S.

    2015-02-11

    We report on the use of quantitative in situ microcompression experiments in a scanning electron microscope to systematically investigate the effect of self-ion irradiation damage on the full plastic response of Ni. In addition to the well-known irradiationinduced increases in the yield and flow strengths with increasing dose, we measure substantial changes in plastic flow intermittency behavior, manifested as stress drops accompanying energy releases as the driven material transits critical states. At low irradiation doses, the magnitude of stress drops reduces relative to the unirradiated material and plastic slip proceeds on multiple slip systems, leading to quasi-homogeneous plastic flow.more »In contrast, highly irradiated specimens exhibit pronounced shear localization on parallel slip planes, which we ascribe to the onset of defect free channels normally seen in bulk irradiated materials. Our in situ testing system and approach allows for a quantitative study of the energy release and dynamics associated with defect free channel formation and subsequent localization. As a result, this study provides fundamental insight to the nature of interactions between mobile dislocations and irradiation-mediated and damage-dependent defect structures.« less

  18. In situ measurements of a homogeneous to heterogeneous transition in the plastic response of ion-irradiated <111> Ni microspecimens

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

    Zhao, Xinyu; Strickland, Daniel J.; Derlet, Peter M.; He, Mo-rigen; Cheng, You -Jung; Pu, Jue; Stanford Univ., Stanford, CA; Hattar, Khalid; Gianola, Daniel S.

    2015-02-11

    We report on the use of quantitative in situ microcompression experiments in a scanning electron microscope to systematically investigate the effect of self-ion irradiation damage on the full plastic response of <111> Ni. In addition to the well-known irradiationinduced increases in the yield and flow strengths with increasing dose, we measure substantial changes in plastic flow intermittency behavior, manifested as stress drops accompanying energy releases as the driven material transits critical states. At low irradiation doses, the magnitude of stress drops reduces relative to the unirradiated material and plastic slip proceeds on multiple slip systems, leading to quasi-homogeneous plastic flow.more » In contrast, highly irradiated specimens exhibit pronounced shear localization on parallel slip planes, which we ascribe to the onset of defect free channels normally seen in bulk irradiated materials. Our in situ testing system and approach allows for a quantitative study of the energy release and dynamics associated with defect free channel formation and subsequent localization. As a result, this study provides fundamental insight to the nature of interactions between mobile dislocations and irradiation-mediated and damage-dependent defect structures.« less

  19. Applying Metal-Organic Frameworks in heterogeneous Catalyisis...

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

    Metal-Organic Frameworks in heterogeneous Catalyisis To control heterogeneous catalysis at atomic and electronic-level represents one of the most challenge research areas....

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

    SciTech Connect (OSTI)

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

    2011-08-05

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

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

    SciTech Connect (OSTI)

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

    2011-12-31

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

  2. Shining Light on Catalysis | Stanford Synchrotron Radiation Lightsource

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

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

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

    SciTech Connect (OSTI)

    Not Available

    1990-03-01

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

  4. A Hydrogen-Evolving Ni(P2N2)2 Electrocatalyst Covalently Attached to a Glassy Carbon Electrode: Preparation, Characterization, and Catalysis. Comparisons With the Homogeneous Analog

    SciTech Connect (OSTI)

    Das, Atanu K.; Engelhard, Mark H.; Bullock, R. Morris; Roberts, John A.

    2014-07-07

    A hydrogen-evolving homogeneous Ni(P2N2)2 electrocatalyst with peripheral ester groups has been covalently attached to a 1,2,3-triazolyllithium-terminated glassy carbon electrode. The surface-confined complex is an electroctalyst for hydrogen evolution, showing onset of catalytic current at the same potential as the soluble parent complex. X-ray photoemission spectra show excellent agreement between the coupled and homogeneous species. Coverage approaches a dense monolayer. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy. The XPS measurements were performed at EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  5. 2012 Catalysis Lectures

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

    Weckhuysen is since 2000 full professor Inorganic Chemistry and Catalysis at Utrecht University (The Netherlands). He is also scientific director of the Netherlands Institute of ...

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

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

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

  7. The impact of nanoscience on heterogeneous catalysis

    SciTech Connect (OSTI)

    Bell, Alexis T.

    2003-03-03

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

  8. In situ measurements of a homogeneous to heterogeneous transition in the plastic response of ion-irradiated <111> Ni microspecimens

    SciTech Connect (OSTI)

    Zhao, Xinyu; Strickland, Daniel J.; Derlet, Peter M.; He, Mo-rigen; Cheng, You -Jung; Pu, Jue; Hattar, Khalid; Gianola, Daniel S.

    2015-02-11

    We report on the use of quantitative in situ microcompression experiments in a scanning electron microscope to systematically investigate the effect of self-ion irradiation damage on the full plastic response of <111> Ni. In addition to the well-known irradiationinduced increases in the yield and flow strengths with increasing dose, we measure substantial changes in plastic flow intermittency behavior, manifested as stress drops accompanying energy releases as the driven material transits critical states. At low irradiation doses, the magnitude of stress drops reduces relative to the unirradiated material and plastic slip proceeds on multiple slip systems, leading to quasi-homogeneous plastic flow. In contrast, highly irradiated specimens exhibit pronounced shear localization on parallel slip planes, which we ascribe to the onset of defect free channels normally seen in bulk irradiated materials. Our in situ testing system and approach allows for a quantitative study of the energy release and dynamics associated with defect free channel formation and subsequent localization. As a result, this study provides fundamental insight to the nature of interactions between mobile dislocations and irradiation-mediated and damage-dependent defect structures.

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

    SciTech Connect (OSTI)

    Behrens, Malte

    2012-03-28

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

  10. Catalysis by heteropoly compounds. XXII. Reactions of esters and esterification catalyzed by heteropolyacids in a homogeneous liquid phase - effects of the central atom of heteropolyanions having tungsten as the addenda atom

    SciTech Connect (OSTI)

    Hu, Changwen; Hashimoto, Masato; Okuhara, Toshio; Misono, Makoto )

    1993-10-01

    Decomposition of isobutyl propionate (IBP) (Reaction (1)), ester exchange of IBP with acetic acid (Reaction (2)), ester exchange of IBP with n-propyl alcohol (Reaction (3)), and esterification of propionic acid with isobutyl alcohol (Reaction (4)) have been studied in a homogeneous liquid phase using heteropolyacids H[sub m]XW[sub 12]O[sub 40] (X = P, Si, Ge, B, and Co) having the Keggin structure and H[sub 6]P[sub 2]W[sub 18]O[sub 62] having the Dawson structure. The results clearly indicated that the catalytic behavior of heteropolyacids remarkably depended on the kind of reaction system, namely, the basicity of reactants. For Reaction (1), the catalytic activities of the heteropolyacids were 60-100 times higher than those of H[sub 2]SO[sub 4] and p-toluenesulfonic acid. Among the heteropolyacids, the activity was in the order H[sub 3]PW[sub 12]O[sub 40] > H[sub 4]SiW[sub 12]O[sub 40] [approximately] H[sub 4]GeW[sub 12]O[sub 40] > H[sub 5]BW[sub 12]O[sub 40] > H[sub 6]CoW[sub 12]O[sub 40]. This order suggests that the activity follows the order of the acid strength of the solutions of heteropolyacids, which increases with the decrease in the negative charge of the polyanion. H[sub 6]P[sub 2]W[sub 18]O[sub 62] showed an activity between those of H[sub 5]BW[sub 12]O[sub 40] and H[sub 6]CoW[sub 12]O[sub 40]. Water molecules in the system retarded Reaction 1. For Reaction 2, the activity order was similar to that for Reaction 1 in the absence of water. However, contrary to Reaction 1, the addition of water greatly accelerated Reaction 2. It was presumed that, in the presence of water, Reaction 2 proceeds via the hydrolysis of IBP to propionic acid and isobutyl alcohol, followed by the esterification of isobutyl alcohol with acetic acid. 28 refs., 8 figs., 4 tabs.

  11. Center for Catalysis at Iowa State University

    SciTech Connect (OSTI)

    Kraus, George A.

    2006-10-17

    The overall objective of this proposal is to enable Iowa State University to establish a Center that enjoys world-class stature and eventually enhances the economy through the transfer of innovation from the laboratory to the marketplace. The funds have been used to support experimental proposals from interdisciplinary research teams in areas related to catalysis and green chemistry. Specific focus areas included: Catalytic conversion of renewable natural resources to industrial materials Development of new catalysts for the oxidation or reduction of commodity chemicals Use of enzymes and microorganisms in biocatalysis Development of new, environmentally friendly reactions of industrial importance These focus areas intersect with barriers from the MYTP draft document. Specifically, section 2.4.3.1 Processing and Conversion has a list of bulleted items under Improved Chemical Conversions that includes new hydrogenation catalysts, milder oxidation catalysts, new catalysts for dehydration and selective bond cleavage catalysts. Specifically, the four sections are: 1. Catalyst development (7.4.12.A) 2. Conversion of glycerol (7.4.12.B) 3. Conversion of biodiesel (7.4.12.C) 4. Glucose from starch (7.4.12.D) All funded projects are part of a soybean or corn biorefinery. Two funded projects that have made significant progress toward goals of the MYTP draft document are: Catalysts to convert feedstocks with high fatty acid content to biodiesel (Kraus, Lin, Verkade) and Conversion of Glycerol into 1,3-Propanediol (Lin, Kraus). Currently, biodiesel is prepared using homogeneous base catalysis. However, as producers look for feedstocks other than soybean oil, such as waste restaurant oils and rendered animal fats, they have observed a large amount of free fatty acids contained in the feedstocks. Free fatty acids cannot be converted into biodiesel using homogeneous base-mediated processes. The CCAT catalyst system offers an integrated and cooperative catalytic system

  12. Multiferroicity of Carbon-Based Charge-Transfer Magnets (Journal...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Energy Frontier Research Centers (EFRC); Argonne-Northwestern Solar Energy ... Subject: catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar ...

  13. Charge-Transfer Induced Magnetic Field Effects of Nano-Carbon...

    Office of Scientific and Technical Information (OSTI)

    Research Org: Energy Frontier Research Centers (EFRC); Argonne-Northwestern Solar Energy ... Subject: catalysis (homogeneous), catalysis (heterogeneous), solar (photovoltaic), solar ...

  14. In Situ Electron Energy-Loss Spectroscopy in Liquids (Journal...

    Office of Scientific and Technical Information (OSTI)

    Subject: catalysis (homogeneous), catalysis (heterogeneous), energy storage (including batteries and capacitors), hydrogen and fuel cells, defects, charge transport, membrane, ...

  15. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... (5) hydrogenation (5) catalysis (homogeneous), catalysis (heterogeneous), biofuels (including algae and biomass), bio-inspired, materials and chemistry by design, ...

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

    SciTech Connect (OSTI)

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

    2011-10-01

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

  17. Zeolite catalysis: technology

    SciTech Connect (OSTI)

    Heinemann, H.

    1980-07-01

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

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

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

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

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

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

    Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make Fuels and Chemicals Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make ...

  20. Catalysis Capabilities | Argonne National Laboratory

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

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

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

    Office of Science (SC) Website

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

  2. Enhanced Micellar Catalysis LDRD.

    SciTech Connect (OSTI)

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

    2012-12-01

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

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

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

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

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

    SciTech Connect (OSTI)

    Zhu, Huiyuan; Zhang, Pengfei; Dai, Sheng

    2015-09-21

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

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

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

    Zhu, Huiyuan; Zhang, Pengfei; Dai, Sheng

    2015-09-21

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

  6. EMSL and Institute for Integrated Catalysis (IIC) Catalysis Workshop

    SciTech Connect (OSTI)

    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

    2011-05-24

    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.

  7. Charge Transfer and Catalysis at the Metal Support Interface

    SciTech Connect (OSTI)

    Baker, Lawrence Robert

    2012-07-31

    Kinetic, electronic, and spectroscopic characterization of model Pt–support systems are used to demonstrate the relationship between charge transfer and catalytic activity and selectivity. The results show that charge flow controls the activity and selectivity of supported metal catalysts. This dissertation builds on extensive existing knowledge of metal–support interactions in heterogeneous catalysis. The results show the prominent role of charge transfer at catalytic interfaces to determine catalytic activity and selectivity. Further, this research demonstrates the possibility of selectively driving catalytic chemistry by controlling charge flow and presents solid-state devices and doped supports as novel methods for obtaining electronic control over catalytic reaction kinetics.

  8. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Everything19 Electronic Full Text6 Citations13 Multimedia0 Datasets0 Software0 Filter Results Filter by Subject solar energy (4) catalysis (homogeneous), catalysis (heterogeneous), ...

  9. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Filter Results Filter by Subject catalysis (homogeneous), catalysis (heterogeneous), energy storage (including batteries and capacitors), hydrogen and fuel cells, defects, charge ...

  10. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... sciences zeolites (1) biofuels (1) biomass vapor-phase upgrading (1) carbocations (1) catalysis (homogeneous), catalysis (heterogeneous), biofuels (including algae and ...

  11. Search for: All records | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Filter Results Filter by Subject basic biological sciences (4) catalysis (homogeneous), catalysis (heterogeneous), biofuels (including algae and biomass), bio-inspired, materials ...

  12. 2013 DOE Catalysis Working Group Meeting Agenda | Department of Energy

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

    13 DOE Catalysis Working Group Meeting Agenda 2013 DOE Catalysis Working Group Meeting Agenda Agenda for the 2013 DOE Catalysis Working Group Meeting on May 15, 2013. cwg_may2013_agenda.pdf (89.11 KB) More Documents & Publications Catalysis Working Group Kick-Off Meeting Agenda DOE Durability Working Group June 2014 Meeting Agenda Catalysis Working Group Meeting: June 2015

  13. Catalysis Working Group | Department of Energy

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

    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

  14. Basic Research Needs: Catalysis for Energy

    SciTech Connect (OSTI)

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

    2008-03-11

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

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

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

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

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

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

    ... D2. Chemical Conversion: Alternatively, the sugars can be converted to fuels or an entire suite of other useful products using chemical catalysis. E. Product Recovery: Products are ...

  17. DOE Catalysis Working Group Meeting

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

    16, 2014 Marriott Wardman Park Hotel 2660 Woodley Road NM, Washington, D.C. 8:30 - 9:00 Continental breakfast: breads, coffee, tea Joint Durability and Catalysis Working Groups Meeting Delaware A 9:00 - 9:05 Welcome & introductory comments DWG co-chairs - Debbie Myers (ANL), Rod Borup (LANL), Donna Ho (DOE); CWG co-chairs - Piotr Zelenay (LANL), Nancy Garland (DOE) 9:05 - 9:25 Are We There Yet? Pt-Alloy Catalyst - Anu Kongkanand (GM) 9:25 - 9:45 Pt-Co/C Catalysts: PEMFC Performance and

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

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

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

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

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

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

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

    Office of Scientific and Technical Information (OSTI)

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

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

    Office of Scientific and Technical Information (OSTI)

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

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

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

    Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts The Bioenergy ...

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

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

    Catalysis by Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx ... Lean NOx Traps - Microstructural Studies of Real World and Model Catalysts Catalysis by ...

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

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

    Fundamental Studies in Catalysis Enabled the use of Efficient "Lean-Burn" Engines for Vehicle Transportation EERE Success Story-Fundamental Studies in Catalysis Enabled the use of ...

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

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

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

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

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

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

  7. "Nanocrystal bilayer for tandem catalysis"

    SciTech Connect (OSTI)

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

    2011-01-24

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

  8. [Zeolite catalysis in conversion of cellulosics

    SciTech Connect (OSTI)

    Tsao, G.T.

    1992-12-31

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

  9. [Zeolite catalysis in conversion of cellulosics

    SciTech Connect (OSTI)

    Tsao, G.T.

    1992-01-01

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

  10. Nanocrystal assembly for tandem catalysis

    DOE Patents [OSTI]

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

    2014-10-14

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

  11. Catalysis and Synthesis | Argonne National Laboratory

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

    Catalysis and Synthesis Catalysis and Synthesis Many different types of chemical reactions depend on catalysts in order to work, and the hunt for better catalysts has deep connections to our nation's economy. From biofuels to plastics, the majority of the products we depend on in our everyday lives rely on catalysts. An estimate from the American Chemical Society found that catalysts and catalytic processes are responsible for more than 20 percent of America's gross domestic product. The

  12. HOMOGENEOUS NUCLEAR POWER REACTOR

    DOE Patents [OSTI]

    King, L.D.P.

    1959-09-01

    A homogeneous nuclear power reactor utilizing forced circulation of the liquid fuel is described. The reactor does not require fuel handling outside of the reactor vessel during any normal operation including complete shutdown to room temperature, the reactor being selfregulating under extreme operating conditions and controlled by the thermal expansion of the liquid fuel. The liquid fuel utilized is a uranium, phosphoric acid, and water solution which requires no gus exhaust system or independent gas recombining system, thereby eliminating the handling of radioiytic gas.

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

    SciTech Connect (OSTI)

    Peden, Charles HF.; Ray, Douglas

    2005-10-05

    Catalysis is one of the most valuable contributors to our economy and historically an area where the United States has enjoyed, but is now losing, international leadership. While other countries are stepping up their work in this area, support for advanced catalysis research and development in the U.S. has diminished. Yet, more than ever, innovative and improved catalyst technologies are imperative for new energy production processes to ease our dependence on imported resources, for new energy-efficient and environmentally benign chemical production processes, and for new emission reduction technologies to minimize the environmental impact of an active and growing economy. Addressing growing concerns about the future direction of U.S. catalysis science, experts from the catalysis community met at a workshop to determine and recommend advanced resources needed to address the grand challenges for catalysis research and development. The workshop's primary conclusion: To recapture our position as the leader in catalysis innovation and practice, and promote crucial breakthroughs, the U.S. must establish one or more well-funded and well-equipped National Catalysis Research Institutes competitively selected, centered in the national laboratories and, by charter, networked to other national laboratories, universities, and industry. The Institute(s) will be the center of a national collaboratory that gives catalysis researchers access to the most advanced techniques available in the scientific enterprise. The importance of catalysis to our energy, economic, and environmental security cannot be overemphasized. Catalysis is a vital part of our core industrial infrastructure, as it is integral to chemical processing and petroleum refining, and is critical to proposed advances needed to secure a sustainable energy future. Advances in catalysis could reduce our need for foreign oil by making better use of domestic carbon resources, for example, allowing cost-effective and zero

  14. HOMOGENEOUS NUCLEAR REACTOR

    DOE Patents [OSTI]

    Hammond, R.P.; Busey, H.M.

    1959-02-17

    Nuclear reactors of the homogeneous liquid fuel type are discussed. The reactor is comprised of an elongated closed vessel, vertically oriented, having a critical region at the bottom, a lower chimney structure extending from the critical region vertically upwardly and surrounded by heat exchanger coils, to a baffle region above which is located an upper chimney structure containing a catalyst functioning to recombine radiolyticallydissociated moderator gages. In operation the liquid fuel circulates solely by convection from the critical region upwardly through the lower chimney and then downwardly through the heat exchanger to return to the critical region. The gases formed by radiolytic- dissociation of the moderator are carried upwardly with the circulating liquid fuel and past the baffle into the region of the upper chimney where they are recombined by the catalyst and condensed, thence returning through the heat exchanger to the critical region.

  15. Synergistic Catalysis between Pd and Fe in Gas Phase Hydrodeoxygenatio...

    Office of Scientific and Technical Information (OSTI)

    Synergistic Catalysis between Pd and Fe in Gas Phase Hydrodeoxygenation of m-Cresol Citation Details In-Document Search Title: Synergistic Catalysis between Pd and Fe in Gas Phase ...

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

    Office of Scientific and Technical Information (OSTI)

    Study of catalysis of coal gasification at elevated pressures. Evaluation of 20 compounds at 850sup 0C Citation Details In-Document Search Title: Study of catalysis of coal ...

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

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

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

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

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

    Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Lean ...

  19. Opportunities in Catalysis Research Using Synchrotron Radiation

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

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

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

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

    Plasma Assisted Catalysis System for NOx Reduction Plasma Assisted Catalysis System for NOx Reduction 2002 DEER Conference Presentation: Noxtech, Inc. 2002_deer_slone.pdf (595.6 KB) More Documents & Publications Noxtechs PAC System Development and Demonstration Lean NOx Catalysis Research and Development

  1. Nanoscale Advances in Catalysis and Energy Applications

    SciTech Connect (OSTI)

    Li, Yimin; Somorjai, Gabor A.

    2010-05-12

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

  2. USD Catalysis Group for Alternative Energy

    SciTech Connect (OSTI)

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

    2012-03-13

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

  3. CNEEC - TRG3: Nanoscale Control in Catalysis

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

    TRG3: Nanoscale control in catalysis TRG3 Leader: Thomas F. Jaramillo Participating CNEEC PI’s: Stacey Bent, Bruce Clemens, Arthur Grossman, Thomas F. Jaramillo, Jens Nørskov, Friedrich Prinz, Jennifer Wilcox The grand challenge in TRG3 is the manipulation of catalyst materials at the nanoscale to significantly improve activity and selectivity for energy conversion reactions. A number of promising renewable energy technologies such as fuel cells and solar fuel reactors depend upon the

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

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

    Bioproducts | Department of Energy Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts Thermochemical Conversion: Using Heat and Catalysis to Make Biofuels and Bioproducts The Bioenergy Technologies Office works with industry to develop pathways that use heat, pressure, and catalysis to convert domestic, non-food biomass into gasoline, jet fuel, and other products. thermochemical_four_pager.pdf (4.64 MB) More Documents & Publications 2013 Peer Review

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

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

    January 2015 Catalysis Working Group Meeting: January 2015 The Catalysis Working Group held a meeting on January 21, 2015, in Los Alamos, New Mexico. Meeting Agenda and Presentations Catalysis Working Group January 2015 Meeting Agenda (22.89 KB) Electrocatalysts with Ultra-Low PGM Loadings-Vojislav Stamenkovic, Argonne National Laboratory (15.95 MB) Improving Stability and Activity of Pt Monolayer in Non-Pt Core-Shell Electrocatalysts-Radoslav Adzic, Brookhaven National Laboratory (3.33 MB)

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

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

    5 Catalysis Working Group Meeting: June 2015 The Catalysis Working Group held a meeting on June 8, 2015, in Arlington, Virginia, in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting. Meeting Agenda and Presentations Catalysis Working Group June 2015 Meeting Agenda (97.68 KB) Non-PGM Catalyst Targets: Summary-Piotr Zelenay, Los Alamos National Laboratory (657.07 KB) Alternative Metal Oxide Supports for Cathode Catalyst Powder in Automotive

  7. Catalysis Working Group Meeting: May 2013 | Department of Energy

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

    Meeting: May 2013 Catalysis Working Group Meeting: May 2013 The Catalysis Working Group held a meeting on May 15, 2013, in Arlington, Virginia, in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting. Agenda Catalysis Working Group Meeting Agenda Presentations Electrocatalysts for Automotive Fuel Cells: Status and Challenges, Nilesh Dale, Nissan Technical Center North America Challenges for PEMFC Catalysts in Automotive Applications, Stephen

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

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

    Catalysis Science Chemical Sciences, Geosciences, & Biosciences (CSGB) Division CSGB Home About Research Areas Energy Frontier Research Centers (EFRCs) DOE Energy Innovation Hubs Reports and Activities Science Highlights Principal Investigators' Meetings BES Home Research Areas Catalysis Science Print Text Size: A A A FeedbackShare Page Notice: NOVEMBER 16, 2015 is the Catalysis Science target date for submission of proposals to be considered for funding within fiscal year 2016. Proposals

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

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

    Low-Temperature HydrocarbonCO Oxidation Catalysis in Support of HCCI Emission Control Vehicle Technologies Office Merit Review 2016: Metal Oxide Nano-Array Catalysts for Low ...

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

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

    Catalysis by Design: Bridging the Gap between Theory and Experiments Catalyst by Design - Theoretical, Nanostructural, and Experimental Studies of Oxidation Catalyst for Diesel ...

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

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Visualizing Group II Intron Catalysis through the Stages of Splicing Citation Details In-Document Search Title: Visualizing Group II ...

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

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

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

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

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

    between Theory and Experiments Catalysis by Design: Bridging the Gap between Theory and Experiments Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research ...

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

    Office of Scientific and Technical Information (OSTI)

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

  15. Computational catalyst screening: Scaling, bond-order and catalysis...

    Office of Scientific and Technical Information (OSTI)

    Computational catalyst screening: Scaling, bond-order and catalysis This content will become publicly available on December 29, 2017 Prev Next Title: Computational catalyst ...

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

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

    Modeling Activity map produced from the new high-throughput computational engine. Example for ethylene glycol catalysis. Reforming, hydrodeoxygenation, dehydrogenation, and ...

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

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

    Lean NOx Catalysis Research and Development Lean NOx Catalysis Research and Development 2003 DEER Conference Presentation: Caterpillar, Inc. 2003_deer_park.pdf (588.44 KB) More Documents & Publications Lean-NOx Catalyst Development for Diesel Engine Applications Fuel Effects on Emissions Control Technologies

  18. Microgrids and Heterogeneous Power Quality and Reliability

    SciTech Connect (OSTI)

    LaCommare, Kristina; Marnay, Chris

    2007-10-01

    This paper describes two stylized alternative visions of how the power system might evolve to meet future requirements for the high quality electricity service that modern digital economies demand, a supergrids paradigm and a dispersed paradigm. Some of the economics of the dispersed vision are explored, and perspectives are presented on both the choice of homogeneous universal power quality upstream in the electricity supply chain and on the extremely heterogeneous requirements of end-use loads. It is argued that meeting the demanding requirements of sensitive loads by local provision of high quality power may be more cost effective than increasing the quality of universal homogeneous supply upstream in the legacy grid. Finally, the potential role of microgrids in delivering heterogeneous power quality is demonstrated by reference to two ongoing microgrid tests in the U.S. and Japan.

  19. Wetting of a Chemically Heterogeneous Surface

    SciTech Connect (OSTI)

    Frink, L.J.D.; Salinger, A.G.

    1998-11-20

    Theories for inhomogeneous fluids have focused in recent years on wetting, capillary conden- sation, and solvation forces for model systems where the surface(s) is(are) smooth homogeneous parallel plates, cylinders, or spherical drops. Unfortunately natural systems are more likely to be hetaogeneous both in surt%ce shape and surface chemistry. In this paper we discuss the conse- quences of chemical heterogeneity on wetting. Specifically, a 2-dimensional implementation of a nonlocal density functional theory is solved for a striped surface model. Both the strength and range of the heterogeneity are varied. Contact angles are calculated, and phase transitions (both the wetting transition and a local layering transition) are located. The wetting properties of the surface ase shown to be strongly dependent on the nature of the surface heterogeneity. In addition highly ordered nanoscopic phases are found, and the operational limits for formation of ordered or crystalline phases of nanoscopic extent are discussed.

  20. Modeling aspects of the dynamic response of heterogeneous materials

    SciTech Connect (OSTI)

    Ionita, Axinte; Clements, Brad; Mas, Eric

    2009-01-01

    In numerical simulations of engineering applications involving heterogeneous materials capturing the local response coming from a distribution of heterogeneities can lead to a very large model thus making simulations difficult. The use of homogenization techniques can reduce the size of the problem but will miss the local effects. Homogenization can also be difficult if the constituents obey different types of constitutive laws. Additional complications arise if inelastic deformation. In such cases a two-scale approach is prefened and tills work addresses these issues in the context of a two-scale Finite Element Method (FEM). Examples of using two-scale FEM approaches are presented.

  1. Catalysis Working Group Meeting: June 2014 | Department of Energy

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

    4 Catalysis Working Group Meeting: June 2014 The Catalysis Working Group held a meeting on June 16, 2014, in Washington, D.C., in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting. Meeting Agenda and Presentations Catalysis Working Group June 2014 Meeting Agenda (100.38 KB) Are We There Yet? Pt-Alloy Catalysts-Anu Kongkanand, GM (1.05 MB) Pt-Co/C Catalysts: PEMFC Performance and Durability-Jim Waldecker, Ford (2.3 MB) Successes and

  2. Coherence delay augmented laser beam homogenizer

    DOE Patents [OSTI]

    Rasmussen, Paul; Bernhardt, Anthony

    1993-01-01

    The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

  3. Coherence delay augmented laser beam homogenizer

    DOE Patents [OSTI]

    Rasmussen, P.; Bernhardt, A.

    1993-06-29

    The geometrical restrictions on a laser beam homogenizer are relaxed by ug a coherence delay line to separate a coherent input beam into several components each having a path length difference equal to a multiple of the coherence length with respect to the other components. The components recombine incoherently at the output of the homogenizer, and the resultant beam has a more uniform spatial intensity suitable for microlithography and laser pantogography. Also disclosed is a variable aperture homogenizer, and a liquid filled homogenizer.

  4. Invariant distributions on compact homogeneous spaces

    SciTech Connect (OSTI)

    Gorbatsevich, V V

    2013-12-31

    In this paper, we study distributions on compact homogeneous spaces, including invariant distributions and also distributions admitting asub-Riemannian structure. We first consider distributions of dimension 1 and 2 on compact homogeneous spaces. After this, we study the cases of compact homogeneous spaces of dimension 2, 3, and 4 in detail. Invariant distributions on simply connected compact homogeneous spaces are also treated. Bibliography: 18 titles.

  5. Catalysis Working Group Kick-Off Meeting Agenda

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

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

  6. Catalysis Center for Energy Innovation: University of Delaware

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

    MAT'LS TRANSFER FORM In The Spotlight Tweets by @CCEIUD Fueling the Quest for Green Energy August 24, 2016 -- Watch an introduction to the University of Delaware's Catalysis ...

  7. Theoretical Study on Catalysis by Protein Enzymes and Ribozyme

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

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

  8. Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC) | U.S.

    Office of Science (SC) Website

    DOE Office of Science (SC) Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC) Energy Frontier Research Centers (EFRCs) EFRCs Home Centers EFRC External Websites Research Science Highlights News & Events Publications History Contact BES Home Centers Integrated Mesoscale Architectures for Sustainable Catalysis (IMASC) Print Text Size: A A A FeedbackShare Page IMASC Header Director Cynthia Friend Lead Institution Harvard University Year Established 2014 Mission To drive

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

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

    Make Fuels and Chemicals | Department of Energy Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make Fuels and Chemicals Biochemical Conversion: Using Hydrolysis, Fermentation, and Catalysis to Make Fuels and Chemicals BETO works with the emerging U.S. bioindustry to sustainably convert non-food biomass resources into cost-competitive biofuels, biopower, and bioproducts. biochemical_four_pager.pdf (2.61 MB) More Documents & Publications Replacing the Whole

  10. Temperature Transient Effects in Plasma-Catalysis | Department of Energy

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

    Temperature Transient Effects in Plasma-Catalysis Temperature Transient Effects in Plasma-Catalysis 2002 DEER Conference Presentation: Ford Motor Company 2002_deer_hoard.pdf (481.22 KB) More Documents & Publications Dynamometer Evaluation of Plasma-Catalyst for Diesel NOx Reduction A Parametric Study of the Effect of Temperature and Hydrocarbon Species on the Product Distribution from a Non-Thermal Plasma Reactor Development of NOx Adsorber System for Dodge Ram 2007 Heavy duty Pickup Truck

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

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

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

  12. Dynamic nuclear polarization solid-state NMR in heterogeneous catalysis research

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

    Kobayashi, Takeshi; Perras, Frédéric A.; Slowing, Igor I.; Sadow, Aaron D.; Pruski, Marek

    2015-10-20

    In this study, a revolution in solid-state nuclear magnetic resonance (SSNMR) spectroscopy is taking place, attributable to the rapid development of high-field dynamic nuclear polarization (DNP), a technique yielding sensitivity improvements of 2–3 orders of magnitude. This higher sensitivity in SSNMR has already impacted materials research, and the implications of new methods on catalytic sciences are expected to be profound.

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

    SciTech Connect (OSTI)

    Ramaker, D.; Koningsberger, D

    2010-01-01

    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.

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

    SciTech Connect (OSTI)

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

    2015-03-04

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

  15. Some General Themes in Catalysis at LANL

    SciTech Connect (OSTI)

    Gordon, John C.

    2012-07-19

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

  16. Studies of Heterogeneously Catalyzed Liquid-Phase Alcohol Oxidation on Platinum bySum-frequency Generation Vibrational Spectroscopy and Reaction Rate Measurements

    SciTech Connect (OSTI)

    Thompson, Christopher

    2014-05-15

    Compared to many branches of chemistry, the molecular level study of catalytically active surfaces is young. Only with the invention of ultrahigh vacuum technology in the past half century has it been possible to carry out experiments that yield useful molecular information about the reactive occurrences at a surface. The reason is two-fold: low pressure is necessary to keep a surface clean for an amount of time long enough to perform an experiment, and most atomic scale techniques that are surface speci c (x-ray photoelectron spectroscopy, electron energy loss spectroscopy, Auger electron spectroscopy, etc.) cannot be used at ambient pressures, because electrons, which act as chemical probes in these techniques, are easily scattered by molecules. Sum-frequency generation (SFG) vibrational spectroscopy is one technique that can provide molecular level information from the surface without the necessity for high vacuum. Since the advent of SFG as a surface spectroscopic tool it has proved its worth in the studies of surface catalyzed reactions in the gas phase, with numerous reactions in the gas phase having been investigated on a multitude of surfaces. However, in situ SFG characterization of catalysis at the solid-liquid interface has yet to be thoroughly pursued despite the broad interest in the use of heterogeneous catalysts in the liquid phase as replacements for homogeneous counterparts. This work describes an attempt to move in that direction, applying SFG to study the solid-liquid interface under conditions of catalytic alcohol oxidation on platinum.

  17. One- and two-dimensional infrared spectroscopic studies of solution-phase homogeneous catalysis and spin-forbidden reactions

    SciTech Connect (OSTI)

    Sawyer, Karma Rae

    2008-12-12

    Understanding chemical reactions requires the knowledge of the elementary steps of breaking and making bonds, and often a variety of experimental techniques are needed to achieve this goal. The initial steps occur on the femto- through picosecond time-scales, requiring the use of ultrafast spectroscopic methods, while the rate-limiting steps often occur more slowly, requiring alternative techniques. Ultrafast one and two-dimensional infrared and step-scan FTIR spectroscopies are used to investigate the photochemical reactions of four organometallic complexes. The analysis leads to a detailed understanding of mechanisms that are general in nature and may be applicable to a variety of reactions.

  18. AQUEOUS HOMOGENEOUS REACTORTECHNICAL PANEL REPORT

    SciTech Connect (OSTI)

    Diamond, D.J.; Bajorek, S.; Bakel, A.; Flanagan, G.; Mubayi, V.; Skarda, R.; Staudenmeier, J.; Taiwo, T.; Tonoike, K.; Tripp, C.; Wei, T.; Yarsky, P.

    2010-12-03

    Considerable interest has been expressed for developing a stable U.S. production capacity for medical isotopes and particularly for molybdenum- 99 (99Mo). This is motivated by recent re-ductions in production and supply worldwide. Consistent with U.S. nonproliferation objectives, any new production capability should not use highly enriched uranium fuel or targets. Conse-quently, Aqueous Homogeneous Reactors (AHRs) are under consideration for potential 99Mo production using low-enriched uranium. Although the Nuclear Regulatory Commission (NRC) has guidance to facilitate the licensing process for non-power reactors, that guidance is focused on reactors with fixed, solid fuel and hence, not applicable to an AHR. A panel was convened to study the technical issues associated with normal operation and potential transients and accidents of an AHR that might be designed for isotope production. The panel has produced the requisite AHR licensing guidance for three chapters that exist now for non-power reactor licensing: Reac-tor Description, Reactor Coolant Systems, and Accident Analysis. The guidance is in two parts for each chapter: 1) standard format and content a licensee would use and 2) the standard review plan the NRC staff would use. This guidance takes into account the unique features of an AHR such as the fuel being in solution; the fission product barriers being the vessel and attached systems; the production and release of radiolytic and fission product gases and their impact on operations and their control by a gas management system; and the movement of fuel into and out of the reactor vessel.

  19. Homogeneous catalysts in hypersonic combustion

    SciTech Connect (OSTI)

    Harradine, D.M.; Lyman, J.L.; Oldenborg, R.C.; Pack, R.T.; Schott, G.L.

    1989-01-01

    Density and residence time both become unfavorably small for efficient combustion of hydrogen fuel in ramjet propulsion in air at high altitude and hypersonic speed. Raising the density and increasing the transit time of the air through the engine necessitates stronger contraction of the air flow area. This enhances the kinetic and thermodynamic tendency of H/sub 2/O to form completely, accompanied only by N/sub 2/ and any excess H/sub 2/(or O/sub 2/). The by-products to be avoided are the energetically expensive fragment species H and/or O atoms and OH radicals, and residual (2H/sub 2/ plus O/sub 2/). However, excessive area contraction raises air temperature and consequent combustion-product temperature by adiabatic compression. This counteracts and ultimately overwhelms the thermodynamic benefit by which higher density favors the triatomic product, H/sub 2/O, over its monatomic and diatomic alternatives. For static pressures in the neighborhood of 1 atm, static temperature must be kept or brought below ca. 2400 K for acceptable stability of H/sub 2/O. Another measure, whose requisite chemistry we address here, is to extract propulsive work from the combustion products early in the expansion. The objective is to lower the static temperature of the combustion stream enough for H/sub 2/O to become adequately stable before the exhaust flow is massively expanded and its composition ''frozen.'' We proceed to address this mechanism and its kinetics, and then examine prospects for enhancing its rate by homogeneous catalysts. 9 refs.

  20. Homogeneously dispersed, multimetal oxygen-evolving catalysts...

    Office of Scientific and Technical Information (OSTI)

    SciTech Connect Search Results Journal Article: Homogeneously dispersed, multimetal oxygen-evolving catalysts Citation ... Publication Date: 2016-03-24 OSTI Identifier: 1245398 Report ...

  1. Dedicated heterogeneous node scheduling including backfill scheduling

    DOE Patents [OSTI]

    Wood, Robert R.; Eckert, Philip D.; Hommes, Gregg

    2006-07-25

    A method and system for job backfill scheduling dedicated heterogeneous nodes in a multi-node computing environment. Heterogeneous nodes are grouped into homogeneous node sub-pools. For each sub-pool, a free node schedule (FNS) is created so that the number of to chart the free nodes over time. For each prioritized job, using the FNS of sub-pools having nodes useable by a particular job, to determine the earliest time range (ETR) capable of running the job. Once determined for a particular job, scheduling the job to run in that ETR. If the ETR determined for a lower priority job (LPJ) has a start time earlier than a higher priority job (HPJ), then the LPJ is scheduled in that ETR if it would not disturb the anticipated start times of any HPJ previously scheduled for a future time. Thus, efficient utilization and throughput of such computing environments may be increased by utilizing resources otherwise remaining idle.

  2. Surfkin: A program to solve transient and steady state heterogeneous reaction kinetics

    SciTech Connect (OSTI)

    COLTRIN,MICHAEL E.; WIXOM,RYAN R.; DANDY,DAVID S.

    2000-05-01

    Heterogeneous chemical reactions occurring at a gas/surface interface are fundamental in a variety of important applications, such as combustion, catalysis, chemical vapor deposition and plasma processing. Detailed simulation of these processes may involve complex, coupled fluid flow, heat transfer, gas-phase chemistry, in addition to heterogeneous reaction chemistry. This report documents the Surfkin program, which simulates the kinetics of heterogeneous chemical reactions. The program is designed for use with the Chemkin and Surface Chemkin (heterogeneous chemistry) programs. It calculates time-dependent or steady state surface site fractions and bulk-species production/destruction rates. The surface temperature may be specified as a function of time to simulate a temperature-programmed desorption experiment, for example. This report serves as a user's manual for the program, explaining the required input and format of the output. Two detailed example problems are included to further illustrate the use of this program.

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

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

    Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control 2002deeraardahl.pdf (7.98 ...

  4. Catalysis Working Group Kick-Off Meeting Agenda | Department of Energy

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

    Catalysis Working Group Kick-Off Meeting Agenda Catalysis Working Group Kick-Off Meeting Agenda Agenda for the kick-off meeting of the U.S. Department of Energy Fuel Cell Technologies Program's Catalysis Working Group, held May 14, 2012, in Arlington, Virginia. 1_cwg_may2012_agenda.pdf (34.13 KB) More Documents & Publications Operando Raman and Theoretical Vibration Spectroscopy of Non-PGM Catalysts 2013 DOE Catalysis Working Group Meeting Agenda Advanced Cathode Catalysts

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

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

    | Department of Energy Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control Plasma-Activated Lean NOx Catalysis for Heavy-Duty Diesel Emissions Control 2002_deer_aardahl.pdf (7.98 MB) More Documents & Publications Heavy-Duty NOx Emissions Control: Reformer-Assisted vs. Plasma-Facilitated Lean NOx Catalysis Selective reduction of NOx in oxygen rich environments with plasma-assisted catalysis: Catalyst development and mechanistic studies

  6. Homogeneous fluorescence linewidths for amorphous hosts

    SciTech Connect (OSTI)

    Lyo, S.K.; Orbach, R.

    1980-11-01

    A contribution to the homogeneous linewidth of optical transitions in amorphous hosts is calculated. The microscopic process is diagonal in the phonon interaction with two level systems (TLS) common to amorphous materials, and diagonal in the coupling between TLS and the optical center. The model predicts an optical homogeneous linewidth proportional to the square of the temperature at low temperature.

  7. Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers

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

    and SCR | Department of Energy Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Transmural Catalysis - High Efficiency Catalyst Systems for NOx Adsorbers and SCR Presentation given at DEER 2006, August 20-24, 2006, Detroit, Michigan. Sponsored by the U.S. DOE's EERE FreedomCar and Fuel Partnership and 21st Century Truck Programs. 2006_deer_atkinson.pdf (327.1 KB) More Documents & Publications Reductant Utilization in a LNT + SCR System Lean NOx Trap

  8. Determining whether metals nucleate homogeneously on graphite: A case study with copper

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

    Appy, David; Lei, Huaping; Han, Yong; Wang, Cai -Zhuang; Tringides, Michael C.; Shao, Dahai; Kwolek, Emma J.; Evans, J. W.; Thiel, P. A.

    2014-11-05

    In this study, we observe that Cu clusters grow on surface terraces of graphite as a result of physical vapor deposition in ultrahigh vacuum. We show that the observation is incompatible with a variety of models incorporating homogeneous nucleation and calculations of atomic-scale energetics. An alternative explanation, ion-mediated heterogeneous nucleation, is proposed and validated, both with theory and experiment. This serves as a case study in identifying when and whether the simple, common observation of metal clusters on carbon-rich surfaces can be interpreted in terms of homogeneous nucleation. We describe a general approach for making system-specific and laboratory-specific predictions.

  9. MRI of Heterogeneous Hydrogenation Reactions Using Parahydrogen Polarization

    SciTech Connect (OSTI)

    Burt, Scott R; Burt, Scott R.

    2008-06-25

    The power of magnetic resonance imaging (MRI) is its ability to image the internal structure of optically opaque samples and provide detailed maps of a variety of important parameters, such as density, diffusion, velocity and temperature. However, one of the fundamental limitations of this technique is its inherent low sensitivity. For example, the low signal to noise ratio (SNR) is particularly problematic for imaging gases in porous materials due to the low density of the gas and the large volume occluded by the porous material. This is unfortunate, as many industrially relevant chemical reactions take place at gas-surface interfaces in porous media, such as packed catalyst beds. Because of this severe SNR problem, many techniques have been developed to directly increase the signal strength. These techniques work by manipulating the nuclear spin populations to produce polarized} (i.e., non-equilibrium) states with resulting signal strengths that are orders of magnitude larger than those available at thermal equilibrium. This dissertation is concerned with an extension of a polarization technique based on the properties of parahydrogen. Specifically, I report on the novel use of heterogeneous catalysis to produce parahydrogen induced polarization and applications of this new technique to gas phase MRI and the characterization of micro-reactors. First, I provide an overview of nuclear magnetic resonance (NMR) and how parahydrogen is used to improve the SNR of the NMR signal. I then present experimental results demonstrating that it is possible to use heterogeneous catalysis to produce parahydrogen-induced polarization. These results are extended to imaging void spaces using a parahydrogen polarized gas. In the second half of this dissertation, I demonstrate the use of parahydrogen-polarized gas-phase MRI for characterizing catalytic microreactors. Specifically, I show how the improved SNR allows one to map parameters important for characterizing the heat and mass

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

    SciTech Connect (OSTI)

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

    2007-09-01

    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

  11. Low temperature, sulfur tolerant homogeneous catalysts for the water-gas shift reaction

    SciTech Connect (OSTI)

    Laine, R.M.

    1986-01-20

    The purpose of this report is to update and reorganize our recent review on homogeneous catalysis of the water-gas shift reaction (WGSR) based on recent literature publications and patents. This updated version will serve as a means of selecting 10 candidate catalyst systems for use in developing effective, sulfur-tolerant, low temperature WGSR catalysts. This report discusses the variations possible in the basic chemistry associated with WGSR catalytic cycles, including basic, acidic, and neutral conditions. Then individual mechanism for specific WGSR catalyst systems are discussed. Finally, on the basis of the literature reports, a list is presented of candidate catalysts and basic systems we have chosen for study in Task 3.

  12. Ionization of large homogeneous and heterogeneous clusters generated in acetylene-Ar expansions: Cluster ion polymerization

    SciTech Connect (OSTI)

    Kocisek, J.; Lengyel, J.; Farnik, M.

    2013-03-28

    Pure acetylene and mixed Ar-acetylene clusters are formed in supersonic expansions of acetylene/argon mixtures and analysed using reflectron time-of-flight mass spectrometer with variable electron energy ionization source. Acetylene clusters composed of more than a hundred acetylene molecules are generated at the acetylene concentration of Almost-Equal-To 8%, while mixed species are produced at low concentrations ( Almost-Equal-To 0.7%). The electron energy dependence of the mass spectra revealed the ionization process mechanisms in clusters. The ionization above the threshold for acetylene molecule of 11.5 eV results in the main ionic fragment progression (C{sub 2}H{sub 2}){sub n}{sup +}. At the electron energies Greater-Than-Or-Slanted-Equal-To 21.5 eV above the CH+CH{sup +} dissociative ionization limit of acetylene the fragment ions nominally labelled as (C{sub 2}H{sub 2}){sub n}CH{sup +}, n Greater-Than-Or-Slanted-Equal-To 2, are observed. For n Less-Than-Or-Slanted-Equal-To 7 these fragments correspond to covalently bound ionic structures as suggested by the observed strong dehydrogenation [(C{sub 2}H{sub 2}){sub n}-k Multiplication-Sign H]{sup +} and [(C{sub 2}H{sub 2}){sub n}CH -k Multiplication-Sign H]{sup +}. The dehydrogenation is significantly reduced in the mixed clusters where evaporation of Ar instead of hydrogen can stabilize the nascent molecular ion. The C{sub 3}H{sub 3}{sup +} ion was previously assigned to originate from the benzene molecular ion; however, the low appearance energy of Almost-Equal-To 13.7 eV indicates that a less rigid covalently bound structure of C{sub 6}H{sub 6}{sup +} ion must also be formed upon the acetylene cluster electron ionization. The appearance energy of Ar{sub n}(C{sub 2}H{sub 2}){sup +} fragments above Almost-Equal-To 15.1 eV indicates that the argon ionization is the first step in the fragment ion production, and the appearance energy of Ar{sub n{>=}2}(C{sub 2}H{sub 2}){sub m{>=}2}{sup +} at Almost-Equal-To 13.7 eV is discussed in terms of an exciton transfer mechanism.

  13. Untangling the Chemical Evolution of Titan's Atmosphere and Surface -- From Homogeneous to Heterogeneous Chemistry

    SciTech Connect (OSTI)

    Kaiser, Ralf I.; Maksyutenko, Pavlo; Ennis, Courtney; Zhang, Fangtong; Gu, Xibin; Krishtal, Sergey P.; Mebel, Alexander M.; Kostko, Oleg; Ahmed, Musahid

    2010-03-16

    The arrival of the Cassini-Huygens probe at Saturn's moon Titan - the only Solar System body besides Earth and Venus with a solid surface and a thick atmosphere with a pressure of 1.4 atm at surface level - in 2004 opened up a new chapter in the history of Solar System exploration. The mission revealed Titan as a world with striking Earth-like landscapes involving hydrocarbon lakes and seas as well as sand dunes and lava-like features interspersed with craters and icy mountains of hitherto unknown chemical composition. The discovery of a dynamic atmosphere and active weather system illustrates further the similarities between Titan and Earth. The aerosol-based haze layers, which give Titan its orange-brownish color, are not only Titan's most prominent optically visible features, but also play a crucial role in determining Titan's thermal structure and chemistry. These smog-like haze layers are thought to be very similar to those that were present in Earth's atmosphere before life developed more than 3.8 billion years ago, absorbing the destructive ultraviolet radiation from the Sun, thus acting as 'prebiotic ozone' to preserve astrobiologically important molecules on Titan. Compared to Earth, Titan's low surface temperature of 94 K and the absence of liquid water preclude the evolution of biological chemistry as we know it. Exactly because of these low temperatures, Titan provides us with a unique prebiotic 'atmospheric laboratory' yielding vital clues - at the frozen stage - on the likely chemical composition of the atmosphere of the primitive Earth. However, the underlying chemical processes, which initiate the haze formation from simple molecules, have been not understood well to date.

  14. Error Assessment of Homogenized Cross Sections Generation for Whole Core Neutronic Calculation

    SciTech Connect (OSTI)

    Hursin, Mathieu; Kochunas, Brendan; Downar, Thomas J.

    2007-10-26

    The objective of the work here was to assess the errors introduced by using 2D, few group homogenized cross sections to perform neutronic analysis of BWR problems with significant axial heterogeneities. The 3D method of characteristics code DeCART is used to generate 2-group assembly homogenized cross sections first using a conventional 2D lattice model and then using a full 3D solution of the assembly. A single BWR fuel assembly model based on an advanced BWR lattice design is used with a typical void distribution applied to the fuel channel coolant. This model is validated against an MCNP model. A comparison of the cross sections is performed for the assembly homogenized planar cross sections from the DeCART 3D and DeCART 2D solutions.

  15. Heterogeneous waste processing

    DOE Patents [OSTI]

    Vanderberg, Laura A.; Sauer, Nancy N.; Brainard, James R.; Foreman, Trudi M.; Hanners, John L.

    2000-01-01

    A combination of treatment methods are provided for treatment of heterogeneous waste including: (1) treatment for any organic compounds present; (2) removal of metals from the waste; and, (3) bulk volume reduction, with at least two of the three treatment methods employed and all three treatment methods emplyed where suitable.

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

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

    Department of Energy between Theory and Experiments Catalysis by Design: Bridging the Gap between Theory and Experiments Poster presentation at the 2007 Diesel Engine-Efficiency & Emissions Research Conference (DEER 2007). 13-16 August, 2007, Detroit, Michigan. Sponsored by the U.S. Department of Energy's (DOE) Office of FreedomCAR and Vehicle Technologies (OFCVT). deer07_narula.pdf (372.33 KB) More Documents & Publications Catalysts via First Principles Catalysts via First

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  4. Assessment of Homogeneous Thorium/Uranium Fuel for Pressurized...

    Office of Scientific and Technical Information (OSTI)

    Fuel for Pressurized Water Reactors Citation Details In-Document Search Title: Assessment of Homogeneous ThoriumUranium Fuel for Pressurized Water Reactors The homogeneous ...

  5. Distribution of Radiation Density in a Homogeneous Cloudy Laye

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

    of Radiation Density in a Homogeneous Cloudy Layer S. V. Dvoryashin, K. A. Shukorov, A. H. ... method) allowing calculating radiation density in homogeneous and non-uniform ...

  6. Anomalous Behavior of the Homogeneous Ice Nucleation Rate in...

    Office of Scientific and Technical Information (OSTI)

    Published Article: Anomalous Behavior of the Homogeneous Ice Nucleation Rate in "No-Man's Land" Prev Next Title: Anomalous Behavior of the Homogeneous Ice Nucleation Rate in ...

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

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

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

  8. Application of cryogenic grinding to achieve homogenization of transuranic wastes

    SciTech Connect (OSTI)

    Atkins, W.H.; Hill, D.D.; Lucero, M.E.; Jaramillo, L.; Martinez, H.E.

    1996-08-01

    This paper describes work done at Los Alamos National Laboratory (LANL) in collaboration with the Department of Energy Rocky Flats Field Office (DOE/RFFO) and with the National Institute of Standards and Technology (NIST), Boulder, Colorado. Researchers on this project have developed a method for cryogenic grinding of mixed wastes to homogenize and, thereby, to acquire a representative sample of the materials. There are approximately 220,000 waste drums owned by the Rocky Flats Environmental Technology Site (RFETS)-50,000 at RFETS and 170,000 at the Idaho National Engineering Laboratory. The cost of sampling the heterogeneous distribution of waste in each drum is prohibitive. In an attempt to produce a homogeneous mixture of waste that would reduce greatly the cost of sampling, researchers at NIST and RFETS are developing a cryogenic grinder. The Los Alamos work herein described addresses the implementation issues of the task. The first issue was to ascertain whether samples of the {open_quotes}small particle{close_quotes} mixtures of materials present in the waste drums at RFETS were representative of actual drum contents. Second, it was necessary to determine at what temperature the grinding operation must be performed in order to minimize or to eliminate the release of volatile organic compounds present in the waste. Last, it was essential to evaluate any effect the liquid cryogen might have on the structural integrity and ventilation capacity of the glovebox system. Results of this study showed that representative samples could be and had been obtained, that some release of organics occurred below freezing because of sublimation, and that operation of the cryogenic grinding equipment inside the glovebox was feasible.

  9. Enhanced Bifunctional Oxygen Catalysis in Strained LaNiO3 Perovskites...

    Office of Scientific and Technical Information (OSTI)

    low temperature oxygen electro catalysis on noble metal films, leading to significant enhancements in bifunctional activity essential for fuel cells and Metal-air batteries. ...

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

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

    Catalysts for Lean NOx Treatment | Department of Energy Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx Treatment Catalysis by Design - Theoretical and Experimental Studies of Model Catalysts for Lean NOx Treatment Presentation given at DEER 2006, August 20-24, 2006, Detroit, Michigan. Sponsored by the U.S. DOE's EERE FreedomCar and Fuel Partnership and 21st Century Truck Programs. 2006_deer_narula.pdf (277.05 KB) More Documents & Publications Lean NOx Traps

  11. USD Catalysis Group for Alternative Energy - Final report

    SciTech Connect (OSTI)

    Hoefelmeyer, James

    2014-10-03

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

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

    SciTech Connect (OSTI)

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

    2007-02-01

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

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

    SciTech Connect (OSTI)

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

    2004-07-01

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

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

    SciTech Connect (OSTI)

    Metiu, Horia

    2014-08-22

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

  15. Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts

    SciTech Connect (OSTI)

    Coble, Inger M

    2008-08-15

    Model heterogeneous catalysts have been synthesized and studied to better understand how the surface structure of noble metal nanoparticles affects catalytic performance. In this project, monodisperse rhodium and platinum nanoparticles of controlled size and shape have been synthesized by solution phase polyol reduction, stabilized by polyvinylpyrrolidone (PVP). Model catalysts have been developed using these nanoparticles by two methods: synthesis of mesoporous silica (SBA-15) in the presence of nanoparticles (nanoparticle encapsulation, NE) to form a composite of metal nanoparticles supported on SBA-15 and by deposition of the particles onto a silicon wafer using Langmuir-Blodgett (LB) monolayer deposition. The particle shapes were analyzed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM) and the sizes were determined by TEM, X-ray diffraction (XRD), and in the case of NE samples, room temperature H2 and CO adsorption isotherms. Catalytic studies were carried out in homebuilt gas-phase reactors. For the nanoparticles supported on SBA-15, the catalysts are in powder form and were studied using the homebuilt systems as plug-flow reactors. In the case of nanoparticles deposited on silicon wafers, the same systems were operated as batch reactors. This dissertation has focused on the synthesis, characterization, and reaction studies of model noble metal heterogeneous catalysts. Careful control of particle size and shape has been accomplished though solution phase synthesis of Pt and Rh nanoparticles in order to elucidate further structure-reactivity relationships in noble metal catalysis.

  16. Characterization of the homogeneous tissue mixture approximation in breast imaging dosimetry

    SciTech Connect (OSTI)

    Sechopoulos, Ioannis; Bliznakova, Kristina; Qin Xulei; Fei Baowei; Feng, Steve Si Jia

    2012-08-15

    Purpose: To compare the estimate of normalized glandular dose in mammography and breast CT imaging obtained using the actual glandular tissue distribution in the breast to that obtained using the homogeneous tissue mixture approximation. Methods: Twenty volumetric images of patient breasts were acquired with a dedicated breast CT prototype system and the voxels in the breast CT images were automatically classified into skin, adipose, and glandular tissue. The breasts in the classified images underwent simulated mechanical compression to mimic the conditions present during mammographic acquisition. The compressed thickness for each breast was set to that achieved during each patient's last screening cranio-caudal (CC) acquisition. The volumetric glandular density of each breast was computed using both the compressed and uncompressed classified images, and additional images were created in which all voxels representing adipose and glandular tissue were replaced by a homogeneous mixture of these two tissues in a proportion corresponding to each breast's volumetric glandular density. All four breast images (compressed and uncompressed; heterogeneous and homogeneous tissue) were input into Monte Carlo simulations to estimate the normalized glandular dose during mammography (compressed breasts) and dedicated breast CT (uncompressed breasts). For the mammography simulations the x-ray spectra used was that used during each patient's last screening CC acquisition. For the breast CT simulations, two x-ray spectra were used, corresponding to the x-ray spectra with the lowest and highest energies currently being used in dedicated breast CT prototype systems under clinical investigation. The resulting normalized glandular dose for the heterogeneous and homogeneous versions of each breast for each modality was compared. Results: For mammography, the normalized glandular dose based on the homogeneous tissue approximation was, on average, 27% higher than that estimated using the

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

    SciTech Connect (OSTI)

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

    2010-04-08

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

  18. Conceptual design of a new homogeneous reactor for medical radioisotope Mo-99/Tc-99m production

    SciTech Connect (OSTI)

    Liem, Peng Hong; Tran, Hoai Nam; Sembiring, Tagor Malem; Arbie, Bakri

    2014-09-30

    To partly solve the global and regional shortages of Mo-99 supply, a conceptual design of a nitrate-fuel-solution based homogeneous reactor dedicated for Mo-99/Tc-99m medical radioisotope production is proposed. The modified LEU Cintichem process for Mo-99 extraction which has been licensed and demonstrated commercially for decades by BATAN is taken into account as a key design consideration. The design characteristics and main parameters are identified and the advantageous aspects are shown by comparing with the BATAN's existing Mo-99 supply chain which uses a heterogeneous reactor (RSG GAS multipurpose reactor)

  19. Fundamental Understanding of the Interaction of Acid Gases with CeO2 : From Surface Science to Practical Catalysis

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

    Tumuluri, Uma; Rother, Gernot; Wu, Zili

    2016-03-21

    Acid gases including CO2, SO2, and NOx are ubiquitous in large-scale energy applications including heterogeneous catalysis. The adverse environmental and health effects of these acid gases have resulted in high interest in the research and development of technologies to remove or convert these acid gases. The main challenge for the development of these technologies is to develop catalysts that are highly efficient, stable, and cost-effective, and many catalysts have been reported in this regard. CeO2 and CeO2-based catalysts have gained prominence in the removal and conversion of CO2, SO2, and NOx because of their structural robustness and redox and acid–basemore » properties. In this article, we provide a brief overview of the application of CeO2 and CeO2-based catalysts for the removal of CO2, SO2, and NOx gases with an emphasis on the fundamental understanding of the interactions of these acid gases with CeO2. The studies summarized in this review range from surface science using single crystals and thin films with precise crystallographic planes to practical catalysis applications of nanocrystalline and polycrystalline CeO2 materials with defects and dopants. After an introduction to the properties of CeO2 surfaces, their catalytic properties for conversions of different acid gases are reviewed and discussed. Lastly, we find that the surface atomic structure, oxygen vacancies, and surface acid–base properties of CeO2 play vital roles in the surface chemistry and structure evolution during the interactions of acid gases with CeO2 and CeO2-based catalysts.« less

  20. Low temperature, sulfur tolerant homogeneous catalysts for the water-gas shift reaction. Task 1, Topical report No. 1

    SciTech Connect (OSTI)

    Laine, R.M.

    1986-01-20

    The purpose of this report is to update and reorganize our recent review on homogeneous catalysis of the water-gas shift reaction (WGSR) based on recent literature publications and patents. This updated version will serve as a means of selecting 10 candidate catalyst systems for use in developing effective, sulfur-tolerant, low temperature WGSR catalysts. This report discusses the variations possible in the basic chemistry associated with WGSR catalytic cycles, including basic, acidic, and neutral conditions. Then individual mechanism for specific WGSR catalyst systems are discussed. Finally, on the basis of the literature reports, a list is presented of candidate catalysts and basic systems we have chosen for study in Task 3.

  1. Microgrids and Heterogeneous Security, Quality, Reliability, andAvailability

    SciTech Connect (OSTI)

    Marnay, Chris

    2007-01-31

    This paper describes two stylized alternative visions inpopular currencyof how the power system might evolve to meet futurerequirements for the high quality electricity service that modern digitaleconomies demand, a supergrids paradigm and a dispersed paradigm. Some ofthe economics of the dispersed vision are explored. Economic perspectivesare presented on both the choice of homogeneous universal power qualityupstream in the electricity supply, and also on the extremelyheterogeneous require-ments of end-use loads. Finally, the potential roleof microgrids in delivering heterogeneous power quality is demonstratedby reference to two ongoing microgrid tests in the U.S. andJapan.

  2. Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports

    SciTech Connect (OSTI)

    Keith James Stanger

    2003-05-31

    The tethered, chiral, chelating diphosphine rhodium complex, which catalyzes the enantioselective hydrogenation of methyl-{alpha}-acetamidocinnamate (MAC), has the illustrated structure as established by {sup 31}P NMR and IR studies. Spectral and catalytic investigations also suggest that the mechanism of action of the tethered complex is the same as that of the untethered complex in solution. The rhodium complexes, [Rh(COD)H]{sub 4}, [Rh(COD){sub 2}]{sup +}BF{sub 4}{sup -}, [Rh(COD)Cl]{sub 2}, and RhCl{sub 3} {center_dot} 3H{sub 2}O, adsorbed on SiO{sub 2} are optimally activated for toluene hydrogenation by pretreatment with H{sub 2} at 200 C. The same complexes on Pd-SiO{sub 2} are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominantly fluorocyclohexane in heptane and 1,2-dichloroethane solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst [-S(CH{sub 2}){sub 3}s-]Re(O)(Me)(PPh{sub 3}) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recyclability, extended stability, and increased resistance to deactivation.

  3. Catalysis Working Group Kick-Off Meeting: May 2012 | Department of Energy

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

    Kick-Off Meeting: May 2012 Catalysis Working Group Kick-Off Meeting: May 2012 The Catalysis Working Group held a kick-off meeting May 14, 2012, in Arlington, Virginia, in conjunction with the DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting. Agenda Catalysis Working Group Kick-off Meeting Agenda Presentations DOE's Fuel Cell Catalyst R&D Activities, Nancy Garland, U.S. Department of Energy Fuel Cells: Just a Dream - or Future Reality, Nenad Markovic,

  4. Homogeneous catalyst formulations for methanol production

    DOE Patents [OSTI]

    Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

    1990-01-01

    There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.13 ), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

  5. Homogeneous catalyst formulations for methanol production

    DOE Patents [OSTI]

    Mahajan, Devinder; Sapienza, Richard S.; Slegeir, William A.; O'Hare, Thomas E.

    1991-02-12

    There is disclosed synthesis of CH.sub.3 OH from carbon monoxide and hydrogen using an extremely active homogeneous catalyst for methanol synthesis directly from synthesis gas. The catalyst operates preferably between 100.degree.-150.degree. C. and preferably at 100-150 psia synthesis gas to produce methanol. Use can be made of syngas mixtures which contain considerable quantities of other gases, such as nitrogen, methane or excess hydrogen. The catalyst is composed of two components: (a) a transition metal carbonyl complex and (b) an alkoxide component. In the simplest formulation, component (a) is a complex of nickel tetracarbonyl and component (b) is methoxide (CH.sub.3 O.sup.-), both being dissolved in a methanol solvent system. The presence of a co-solvent such as p-dioxane, THF, polyalcohols, ethers, hydrocarbons, and crown ethers accelerates the methanol synthesis reaction.

  6. Soliton production with nonlinear homogeneous lines

    SciTech Connect (OSTI)

    Elizondo-Decanini, Juan M.; Coleman, Phillip D.; Moorman, Matthew W.; Petney, Sharon Joy Victor; Dudley, Evan C.; Youngman, Kevin; Penner, Tim Dwight; Fang, Lu; Myers, Katherine M.

    2015-11-24

    Low- and high-voltage Soliton waves were produced and used to demonstrate collision and compression using diode-based nonlinear transmission lines. Experiments demonstrate soliton addition and compression using homogeneous nonlinear lines. We built the nonlinear lines using commercially available diodes. These diodes are chosen after their capacitance versus voltage dependence is used in a model and the line design characteristics are calculated and simulated. Nonlinear ceramic capacitors are then used to demonstrate high-voltage pulse amplification and compression. The line is designed such that a simple capacitor discharge, input signal, develops soliton trains in as few as 12 stages. We also demonstrated output voltages in excess of 40 kV using Y5V-based commercial capacitors. The results show some key features that determine efficient production of trains of solitons in the kilovolt range.

  7. Soliton production with nonlinear homogeneous lines

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

    Elizondo-Decanini, Juan M.; Coleman, Phillip D.; Moorman, Matthew W.; Petney, Sharon Joy Victor; Dudley, Evan C.; Youngman, Kevin; Penner, Tim Dwight; Fang, Lu; Myers, Katherine M.

    2015-11-24

    Low- and high-voltage Soliton waves were produced and used to demonstrate collision and compression using diode-based nonlinear transmission lines. Experiments demonstrate soliton addition and compression using homogeneous nonlinear lines. We built the nonlinear lines using commercially available diodes. These diodes are chosen after their capacitance versus voltage dependence is used in a model and the line design characteristics are calculated and simulated. Nonlinear ceramic capacitors are then used to demonstrate high-voltage pulse amplification and compression. The line is designed such that a simple capacitor discharge, input signal, develops soliton trains in as few as 12 stages. We also demonstrated outputmore » voltages in excess of 40 kV using Y5V-based commercial capacitors. The results show some key features that determine efficient production of trains of solitons in the kilovolt range.« less

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

    Broader source: Energy.gov [DOE]

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

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

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

    Nanoscale Level | Department of Energy Between Theory and Experiments at Nanoscale Level Catalysis by Design: Bridging the Gap Between Theory and Experiments at Nanoscale Level Studies on a simple platinum-alumina system constitute a first step toward a "catalyst by design" approach. deer08_narula.pdf (273.18 KB) More Documents & Publications Catalysis by Design: Bridging the Gap between Theory and Experiments Catalyst by Design - Theoretical, Nanostructural, and Experimental

  10. Center for Biological Electron Transfer and Catalysis (BETCy) | U.S. DOE

    Office of Science (SC) Website

    Office of Science (SC) Center for Biological Electron Transfer and Catalysis (BETCy) Energy Frontier Research Centers (EFRCs) EFRCs Home Centers EFRC External Websites Research Science Highlights News & Events Publications History Contact BES Home Centers Center for Biological Electron Transfer and Catalysis (BETCy) Print Text Size: A A A FeedbackShare Page BETCy Header Director John Peters Lead Institution Montana State University Year Established 2014 Mission To investigate the

  11. The Catalysis Center for Energy Innovation is an Energy Frontier Research Center

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

    Friday, September 2, 2016 11:00 AM  322 ISE Yong Wang The Gene & Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University Institute for Integrated Catalysis, Pacific Northwest National Laboratory College of Chemistry and Chemical Engineering, Xiamen University Biography: Dr. Wang joined PNNL in 1994 and was promoted to Laboratory Fellow (highest scientific rank in national labs) in 2005. He led the Catalysis and Reaction Engineering Team from 2000 to

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

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

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

  13. Density Functional Theory in Surface Chemistry and Catalysis

    SciTech Connect (OSTI)

    Norskov, Jens

    2011-05-19

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

  14. Foam Generation in Homogeneous Porous Media

    SciTech Connect (OSTI)

    Gauglitz, Phillip A.; Friedman, F.; Kam, S. I.; Rossen, W. R.

    2002-10-01

    In steady gas-liquid flow in homogeneous porous media with surfactant present, there is often observed a critical injection velocity or pressure gradient ?grad p min? at which ?weak? or ?coarse? foam is abruptly converted into ?strong foam,? with reduction of one to two orders of magnitude in total mobility: i.e., ?foam generation.? Earlier research on foam generation is extended here with extensive data for a variety of porous media, permeabilities, gases (N2 and C02), surfactants, and temperatures. For bead and sandpacks, ?grad p min? scales like (1/k), where k is permeability, over 2 1/2 orders of magnitude in k; for consolidated media the relation is more complex. For dense C02 foam, ?grad p min? exists but can be less than 1 psi/ft. If pressure drop, rather than flow rates, is fixed, one observes and unstable regime between stable ?strong? and ?coarse? foam regimes; in the unstable regime ?grad p? is nonuniform in space or variable in time.

  15. Homogeneously dispersed, multimetal oxygen-evolving catalysts

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

    Zhang, Bo; Zheng, Xueli; Voznyy, Oleksandr; Comin, Riccardo; Bajdich, Michal; Garcia-Melchor, Max; Han, Lili; Xu, Jixian; Liu, Min; Zheng, Lirong; et al

    2016-03-24

    Earth-abundant first-row (3d) transition-metal-based catalysts have been developed for the oxygen-evolution reaction (OER); however, they operate at overpotentials significantly above thermodynamic requirements. Density functional theory suggested that non-3d high-valency metals such as tungsten can modulate 3d metal oxides, providing near-optimal adsorption energies for OER intermediates. We developed a room-temperature synthesis to produce gelled oxy-hydroxide materials with an atomically homogeneous metal distribution. These gelled FeCoW oxy-hydroxide exhibits the lowest overpotential (191 mV) reported at 10 mA per square centimeter in alkaline electrolyte. Here, the catalyst shows no evidence of degradation following more than 500 hours of operation. X-ray absorption and computationalmore » studies reveal a synergistic interplay between W, Fe and Co in producing a favorable local coordination environment and electronic structure that enhance the energetics for OER.« less

  16. NOX REDUCTION FOR LEAN EXHAUST USING PLASMA ASSISTED CATALYSIS

    SciTech Connect (OSTI)

    Bhatt, B.

    2000-08-20

    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

  17. A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - I. Theory

    SciTech Connect (OSTI)

    Williams, Mark L.; Lee, Deokjung; Choi, Sooyoung

    2015-03-04

    A new methodology has been developed to treat resonance self-shielding in doubly heterogeneous very high temperature gas-cooled reactor systems in which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. This new method first homogenizes the fuel grain and matrix materials using an analytically derived disadvantage factor from a two-region problem with equivalence theory and intermediate resonance method. This disadvantage factor accounts for spatial self-shielding effects inside each grain within the framework of an infinite array of grains. Then the homogenized fuel compact is self-shielded using a Bondarenko method to account for interactions between the fuel compact regions in the fuel lattice. In the final form of the equations for actual implementations, the double-heterogeneity effects are accounted for by simply using a modified definition of a background cross section, which includes geometry parameters and cross sections for both the grain and fuel compact regions. With the new method, the doubly heterogeneous resonance self-shielding effect can be treated easily even with legacy codes programmed only for a singly heterogeneous system by simple modifications in the background cross section for resonance integral interpolations. This paper presents a detailed derivation of the new method and a sensitivity study of double-heterogeneity parameters introduced during the derivation. The implementation of the method and verification results for various test cases are presented in the companion paper.

  18. A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - I. Theory

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

    Williams, Mark L.; Lee, Deokjung; Choi, Sooyoung

    2015-03-04

    A new methodology has been developed to treat resonance self-shielding in doubly heterogeneous very high temperature gas-cooled reactor systems in which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. This new method first homogenizes the fuel grain and matrix materials using an analytically derived disadvantage factor from a two-region problem with equivalence theory and intermediate resonance method. This disadvantage factor accounts for spatial self-shielding effects inside each grain within the framework of an infinite array of grains. Then the homogenized fuel compact is self-shielded using a Bondarenko method to accountmore » for interactions between the fuel compact regions in the fuel lattice. In the final form of the equations for actual implementations, the double-heterogeneity effects are accounted for by simply using a modified definition of a background cross section, which includes geometry parameters and cross sections for both the grain and fuel compact regions. With the new method, the doubly heterogeneous resonance self-shielding effect can be treated easily even with legacy codes programmed only for a singly heterogeneous system by simple modifications in the background cross section for resonance integral interpolations. This paper presents a detailed derivation of the new method and a sensitivity study of double-heterogeneity parameters introduced during the derivation. The implementation of the method and verification results for various test cases are presented in the companion paper.« less

  19. Computationally Optimized Homogenization Heat Treatment of Metal Alloys -

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

    Energy Innovation Portal Industrial Technologies Industrial Technologies Advanced Materials Advanced Materials Find More Like This Return to Search Computationally Optimized Homogenization Heat Treatment of Metal Alloys National Energy Technology Laboratory Contact NETL About This Technology Publications: PDF Document Publication Computationally Optimized Homogenization Heat Treatment of Metal Alloys (291 KB) Technology Marketing Summary ? A computational approach has been developed to

  20. State of Supported Nickel Nanoparticles during Catalysis in Aqueous Media

    SciTech Connect (OSTI)

    Chase, Zizwe; Kasakov, Stanislav; Shi, Hui; Vjunov, Aleksei; Fulton, John L.; Camaioni, Donald M.; Balasubramanian, Mahalingam; Zhao, Chen; Wang, Yong; Lercher, Johannes A.

    2015-11-09

    The state of Ni supported on HZSM-5 zeolite, silica, and sulfonated carbon was determined during aqueous phase catalysis of phenol hydrodeoxygenation using in situ extended X-ray absorption fine structure spectroscopy (EXAFS). On sulfonated carbon and HZSM-5 supports, the NiO and Ni(OH)2 were readily reduced to Ni(0) under reaction conditions (~35 bar H2 in aqueous phenol solutions containing up to 0.5 wt. % phosphoric acid at 473 K). On the silica support, less than 70% of the Ni was converted to Ni(0) under reaction conditions, which is attributed to the formation of Ni phyllosilicates. Over a broad range of reaction conditions there was no leaching of Ni from the supports. In contrast, rapid leaching of the Ni(II) from HZSM-5 was observed, when 15 wt. % aqueous acetic acid was substituted for the aqueous phenol solution. Once the metallic state of Ni was established there was no leaching in 15 wt. % acetic acid at 473 K and 35 bar H2. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences (BES), Division of Chemical Sciences, Geosciences & Biosciences. The STEM was supported under the Laboratory Directed Research and Development Program: Chemical Imaging Initiative at Pacific Northwest National Laboratory (PNNL), a multi-program national laboratory operated for DOE by Battelle under Contract DE-AC05-76RL01830. STEM was performed at EMSL, a DOE Office of Science user facility sponsored by the Office of Biological and Environmental Research and located at PNNL.

  1. Shape-selective catalysis in dimethyl ether conversion

    SciTech Connect (OSTI)

    Sardesai, A.; Lee, S.

    1999-07-01

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

  2. Structural Insights into the Mechanism of PEPCK Catalysis

    SciTech Connect (OSTI)

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

    2006-01-01

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

  3. Molecular-level Design of Heterogeneous Chiral Catalysts

    SciTech Connect (OSTI)

    Gellman, Andrew John; Sholl, David S.; Tysoe, Wilfred T.; Zaera, Francisco

    2013-04-28

    Understanding and controlling selectivity is one of the key challenges in heterogeneous catalysis. Among problems in catalytic selectivity enantioselectivity is perhaps the most the most challenging. The primary goal of the project on Molecular-level Design of Heterogeneous Chiral Catalysts is to understand the origins of enantioselectivity on chiral heterogeneous surfaces and catalysts. The efforts of the project team include preparation of chiral surfaces, characterization of chiral surfaces, experimental detection of enantioselectivity on such surfaces and computational modeling of the interactions of chiral probe molecules with chiral surfaces. Over the course of the project period the team of PIs has made some of the most detailed and insightful studies of enantioselective chemistry on chiral surfaces. This includes the measurement of fundamental interactions and reaction mechanisms of chiral molecules on chiral surfaces and leads all the way to rationale design and synthesis of chiral surfaces and materials for enantioselective surface chemistry. The PIs have designed and prepared new materials for enantioselective adsorption and catalysis. Naturally Chiral Surfaces Completion of a systematic study of the enantiospecific desorption kinetics of R-3-methylcyclohexanone (R-3-MCHO) on 9 achiral and 7 enantiomeric pairs of chiral Cu surfaces with orientations that span the stereographic triangle. Discovery of super-enantioselective tartaric acid (TA) and aspartic acid (Asp) decomposition as a result of a surface explosion mechanism on Cu(643)R&S. Systematic study of super-enantiospecific TA and Asp decomposition on five enantiomeric pairs of chiral Cu surfaces. Initial observation of the enantiospecific desorption of R- and S-propylene oxide (PO) from Cu(100) imprinted with {3,1,17} facets by L-lysine adsorption. Templated Chiral Surfaces Initial observation of the enantiospecific desorption of R- and S-PO from Pt(111) and Pd(111) modified by a variety

  4. Organusulfur Catalysis With Reduced Molybdenum Sulfides Containing the Mo6S8 Cluster

    SciTech Connect (OSTI)

    Thomas Jay Paskach

    2002-08-27

    Industrial synthesis of sulfur-containing organic chemicals basically focuses on the broad categories of mercaptans (thiols), alkylsulfides (thioethers), polysulfides, and thiophenes. Of the organo-sulfur compounds produced, by far the most important in terms of quantities produced is methyl mercaptan (methanethiol or MeSH), which is produced mainly for the downstream production of methionine and methanesulfonyl chloride. Higher thiols are also used in the manufacture of rubber and plastics as polymerization regulators, chain transfer agents, or initiators. Other important organosulfur chemicals are dimethyl sulfide (DMS) and dimethyl disulfide (DMDS), both of which are used extensively for presulfiding of industrial hydroprocessing catalysts, and substituted thiophenes which are used as intermediates for production of agrochemicals, dyes, and pharmaceuticals. Thiols are produced commercially at the rate of about 10{sup 4} ton/yr from hydrogen sulfide (H{sub 2}S) and alcohols or olefins, using homogeneous free-radical synthesis, or heterogeneous catalysts based on solid acids or supported metal oxides and/or sulfides. Despite this large production rate, and the industrial importance of the organosulfur compounds, only limited research has been devoted to the development of new catalytic materials for their synthesis. Additionally, for most organosulfur catalytic reactions, only limited information exists about reaction mechanisms, active sites, adsorbed surface species, and especially the nature of the catalysts under reaction conditions.

  5. At tank Low Activity Feed Homogeneity Analysis Verification

    SciTech Connect (OSTI)

    DOUGLAS, J.G.

    2000-09-28

    This report evaluates the merit of selecting sodium, aluminum, and cesium-137 as analytes to indicate homogeneity of soluble species in low-activity waste (LAW) feed and recommends possible analytes and physical properties that could serve as rapid screening indicators for LAW feed homogeneity. The three analytes are adequate as screening indicators of soluble species homogeneity for tank waste when a mixing pump is used to thoroughly mix the waste in the waste feed staging tank and when all dissolved species are present at concentrations well below their solubility limits. If either of these conditions is violated, then the three indicators may not be sufficiently chemically representative of other waste constituents to reliably indicate homogeneity in the feed supernatant. Additional homogeneity indicators that should be considered are anions such as fluoride, sulfate, and phosphate, total organic carbon/total inorganic carbon, and total alpha to estimate the transuranic species. Physical property measurements such as gamma profiling, conductivity, specific gravity, and total suspended solids are recommended as possible at-tank methods for indicating homogeneity. Indicators of LAW feed homogeneity are needed to reduce the U.S. Department of Energy, Office of River Protection (ORP) Program's contractual risk by assuring that the waste feed is within the contractual composition and can be supplied to the waste treatment plant within the schedule requirements.

  6. Th/U-233 multi-recycle in pressurized water reactors : feasibility study of multiple homogeneous and heterogeneous assembly designs.

    SciTech Connect (OSTI)

    Yun, D.; Taiwo, T. A.; Kim, T. K.; Mohamed, A.; Nuclear Engineering Division

    2010-10-01

    The use of thorium in current or advanced light water reactors (LWRs) has been of interest in recent years. These interests have been associated with the need to increase nuclear fuel resources and the perceived non-proliferation advantages of the utilization of thorium in the fuel cycle. Various options have been considered for the use of thorium in the LWR fuel cycle. The possibility for thorium utilization in a multi-recycle system has also been considered in past literature, primarily because of the potential for near breeders with Th/U-233 in the thermal energy range. The objective of this study is to evaluate the potential of Th/U-233 fuel multi-recycle in current LWRs, focusing on pressurized water reactors (PWRs). Approaches for sustainable multi-recycle without the need for external fissile material makeup have been investigated. The intent is to obtain a design that allows existing PWRs to be used with minimal modifications.

  7. Computational Spectroscopy of Heterogeneous Interfaces | Argonne...

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

    N. Brawand, University of Chicago Computational Spectroscopy of Heterogeneous Interfaces ... Year: 2016 Research Domain: Materials Science The interfaces between solids, ...

  8. 2010 CATALYSIS GORDON RESEARCH CONFERENCE, JUNE 27 - JULY 2, 2010, NEW LONDON, NEW HAMPSHIRE

    SciTech Connect (OSTI)

    Abhaya Datye

    2010-07-02

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

  9. Hydrogen storage materials and method of making by dry homogenation

    DOE Patents [OSTI]

    Jensen, Craig M.; Zidan, Ragaiy A.

    2002-01-01

    Dry homogenized metal hydrides, in particular aluminum hydride compounds, as a material for reversible hydrogen storage is provided. The reversible hydrogen storage material comprises a dry homogenized material having transition metal catalytic sites on a metal aluminum hydride compound, or mixtures of metal aluminum hydride compounds. A method of making such reversible hydrogen storage materials by dry doping is also provided and comprises the steps of dry homogenizing metal hydrides by mechanical mixing, such as be crushing or ball milling a powder, of a metal aluminum hydride with a transition metal catalyst. In another aspect of the invention, a method of powering a vehicle apparatus with the reversible hydrogen storage material is provided.

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

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

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

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

    SciTech Connect (OSTI)

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

    2014-04-14

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

  12. Progress on Acidic Zirconia Mixed Oxides for Efficient NH3-SCR Catalysis |

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

    Department of Energy Acidic Zirconia Mixed Oxides for Efficient NH3-SCR Catalysis Progress on Acidic Zirconia Mixed Oxides for Efficient NH3-SCR Catalysis Details progress on non-zeolitic zirconia-based mixed oxides as promising new SCR catalyst materials and results of engine bench testing of full-size SCR prototype confirms Details progress on non-zeolitic zirconia-based mixed oxides as promising new SCR catalyst materials and results of engine bench testing of full-size SCR prototype

  13. Tritium Technology Program TTP-1-3089 TPBAR Homogenized Composition

    SciTech Connect (OSTI)

    Love, Edward F.

    2014-10-12

    Homogenized TPBAR number densities contained herein have been derived for unclassified core physics calculations. The use of this information may not provide accurate, conservative or representative results and must be evaluated for applicability to the specific problem.

  14. Surface functionalization of metal-organic polyhedron for homogeneous...

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

    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...

  15. Enzyme-Like Catalysis of the Nazarov Cyclization by Supramolecular Encapsulation

    SciTech Connect (OSTI)

    Hastings, Courtney; Pluth, Michael; Bergman, Robert; Raymond, Kenneth

    2010-03-29

    A primary goal in the design and synthesis of molecular hosts has been the selective recognition and binding of a variety of guests using non-covalent interactions. Supramolecular catalysis, which is the application of such hosts towards catalysis, has much in common with many enzymatic reactions, chiefly the use of both spatially appropriate binding pockets and precisely oriented functional groups to recognize and activate specific substrate molecules. Although there are now many examples which demonstrate how selective encapsulation in a host cavity can enhance the reactivity of a bound guest, all have failed to reach the degree of increased reactivity typical of enzymes. We now report the catalysis of the Nazarov cyclization by a self-assembled coordination cage, a carbon-carbon bond-forming reaction which proceeds under mild, aqueous conditions. The acceleration in this system is over a million-fold, and represents the first example of supramolecular catalysis that achieves the level of rate enhancement comparable to that observed in several enzymes. We explain the unprecedented degree of rate increase as due to the combination of (a) preorganization of the encapsulated substrate molecule, (b) stabilization of the transition state of the cyclization by constrictive binding, and (c) increase in the basicity of the complexed alcohol functionality.

  16. Chemistry - Oxygen Vacancies and Catalysis on Ceria Surfaces

    SciTech Connect (OSTI)

    Campbell, Charles T.; Peden, Charles HF.

    2005-07-29

    Chemistry occurring at the surface of metal oxides is critical in a variety of industrial applications including catalysis and photocatalysis, optical display technology, solar energy devices and corrosion prevention. Defects have long been recognized to be the most reactive sites on the surfaces of many oxide materials. The most common types of defects present on the surfaces of metal oxides are oxygen vacancies and step edges. The nature of surface oxygen vacancies, and their number, distribution and diffusion across the surface of oxides, are thus issues of major scientific importance. One of the most interesting oxides in this respect is CeO2, since oxygen vacancies play the key role in giving this material it's industrially important ''oxygen-storage capacity''. This capacity makes modern automotive exhaust treatment catalysts containing CeO2 much more effective than their predecessors without CeO2. Ceria is also well known as a support which enhances the performance of transition metal catalysts, relative to other oxide supports, in a variety of other reactions including water-gas shift, steam reforming of oxygenates and PROX 1-7, all of which hold promise for enabling a hydrogen economy 1. Related to ceria's facile redox capacity (ability to rapidly form and eliminate oxygen vacancy defects) is the poorly understood observation that some less reducible oxides, such as zirconia (ZrO2), are used as additives that actually enhance this ''oxygen storage'' property of CeO2. In this issue, Esch and coworkers in Trieste, Italy report an exciting study that for the first time clearly elucidates the structure, distribution and formation of oxygen vacancies on a cerium oxide surface 8. They have elegantly combined beautiful, atomic-resolution imaging using scanning-tunneling microscopy (STM) on a ceria surface with state-of-the-art quantum mechanical calculations using Density Functional Theory (DFT) to raise our understanding of CeO2 surfaces to a much higher level

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

    SciTech Connect (OSTI)

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

    2012-02-01

    Kinetic, spectroscopic, and chemical titration data indicate that differences in monomolecular isobutane cracking and dehydrogenation and methanol dehydration turnover rates (per H+) among FAU zeolites treated thermally with steam (H-USY) and then chemically with ammonium hexafluorosilicate (CDHUSY) predominantly reflect differences in the size and solvating properties of their supercage voids rather than differences in acid strength. The number of protons on a given sample was measured consistently by titrations with Na+, with CH3 groups via reactions of dimethyl ether, and with 2,6-di-tert-butylpyridine during methanol dehydration catalysis; these titration values were also supported by commensurate changes in acidic OH infrared band areas upon exposure to titrant molecules. The number of protons, taken as the average of the three titration methods, was significantly smaller than the number of framework Al atoms (Alf) obtained from X-ray diffraction and 27Al magic angle spinning nuclear magnetic resonance spectroscopy on H-USY (0.35 H+/Alf) and CD-HUSY (0.69 H+/Alf). These data demonstrate that the ubiquitous use of Alf sites as structural proxies for active H+ sites in zeolites can be imprecise, apparently because distorted Al structures that are not associated with acidic protons are sometimes detected as Alf sites. Monomolecular isobutane cracking and dehydrogenation rate constants, normalized non-rigorously by the number of Alf species, decreased with increasing Na+ content on both H-USY and CD-HUSY samples and became undetectable at sub-stoichiometric exchange levels (0.32 and 0.72 Na+/Alf ratios, respectively), an unexpected finding attributed incorrectly in previous studies to the presence of minority ‘‘super-acidic’’ sites. These rate constants, when normalized rigorously by the number of residual H+ sites were independent of Na+ content on both H-USY and CD-HUSY samples, reflecting the stoichiometric replacement of protons that are uniform in

  18. Modelling long-distance seed dispersal in heterogeneous landscapes.

    SciTech Connect (OSTI)

    Levey, Douglas, J.; Tewlsbury, Joshua, J.; Bolker, Benjamin, M.

    2008-01-01

    1. Long-distance seed dispersal is difficult to measure, yet key to understanding plant population dynamics and community composition. 2. We used a spatially explicit model to predict the distribution of seeds dispersed long distances by birds into habitat patches of different shapes. All patches were the same type of habitat and size, but varied in shape. They occurred in eight experimental landscapes, each with five patches of four different shapes, 150 m apart in a matrix of mature forest. The model was parameterized with smallscale movement data collected from field observations of birds. In a previous study we validated the model by testing its predictions against observed patterns of seed dispersal in real landscapes with the same types and spatial configuration of patches as in the model. 3. Here we apply the model more broadly, examining how patch shape influences the probability of seed deposition by birds into patches, how dispersal kernels (distributions of dispersal distances) vary with patch shape and starting location, and how movement of seeds between patches is affected by patch shape. 4. The model predicts that patches with corridors or other narrow extensions receive higher numbers of seeds than patches without corridors or extensions. This pattern is explained by edgefollowing behaviour of birds. Dispersal distances are generally shorter in heterogeneous landscapes (containing patchy habitat) than in homogeneous landscapes, suggesting that patches divert the movement of seed dispersers, holding them long enough to increase the probability of seed defecation in the patches. Dispersal kernels for seeds in homogeneous landscapes were smooth, whereas those in heterogenous landscapes were irregular. In both cases, long-distance (> 150 m) dispersal was surprisingly common, usually comprising approximately 50% of all dispersal events. 5. Synthesis . Landscape heterogeneity has a large influence on patterns of long-distance seed dispersal. Our results

  19. A Computationally Based Approach to Homogenizing Advanced Alloys

    SciTech Connect (OSTI)

    Jablonski, P D; Cowen, C J

    2011-02-27

    We have developed a computationally based approach to optimizing the homogenization heat treatment of complex alloys. The Scheil module within the Thermo-Calc software is used to predict the as-cast segregation present within alloys, and DICTRA (Diffusion Controlled TRAnsformations) is used to model the homogenization kinetics as a function of time, temperature and microstructural scale. We will discuss this approach as it is applied to both Ni based superalloys as well as the more complex (computationally) case of alloys that solidify with more than one matrix phase as a result of segregation. Such is the case typically observed in martensitic steels. With these alloys it is doubly important to homogenize them correctly, especially at the laboratory scale, since they are austenitic at high temperature and thus constituent elements will diffuse slowly. The computationally designed heat treatment and the subsequent verification real castings are presented.

  20. Variable valve timing in a homogenous charge compression ignition engine

    DOE Patents [OSTI]

    Lawrence, Keith E.; Faletti, James J.; Funke, Steven J.; Maloney, Ronald P.

    2004-08-03

    The present invention relates generally to the field of homogenous charge compression ignition engines, in which fuel is injected when the cylinder piston is relatively close to the bottom dead center position for its compression stroke. The fuel mixes with air in the cylinder during the compression stroke to create a relatively lean homogeneous mixture that preferably ignites when the piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. The present invention utilizes internal exhaust gas recirculation and/or compression ratio control to control the timing of ignition events and combustion duration in homogeneous charge compression ignition engines. Thus, at least one electro-hydraulic assist actuator is provided that is capable of mechanically engaging at least one cam actuated intake and/or exhaust valve.

  1. Heterogeneous Reburning By Mixed Fuels

    SciTech Connect (OSTI)

    Anderson Hall

    2009-03-31

    Recent studies of heterogeneous reburning, i.e., reburning involving a coal-derived char, have elucidated its variables, kinetics and mechanisms that are valuable to the development of a highly efficient reburning process. Young lignite chars contain catalysts that not only reduce NO, but they also reduce HCN that is an important intermediate that recycles to NO in the burnout zone. Gaseous CO scavenges the surface oxides that are formed during NO reduction, regenerating the active sites on the char surface. Based on this mechanistic information, cost-effective mixed fuels containing these multiple features has been designed and tested in a simulated reburning apparatus. Remarkably high reduction of NO and HCN has been observed and it is anticipated that mixed fuel will remove 85% of NO in a three-stage reburning process.

  2. Comprehensive Monitoring for Heterogeneous Geographically Distributed...

    Office of Scientific and Technical Information (OSTI)

    Comprehensive Monitoring for Heterogeneous Geographically Distributed Storage Citation ... Sponsoring Org: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25) Country of ...

  3. The effect of reservoir heterogeneity on gas production from hydrate accumulations in the permafrost

    SciTech Connect (OSTI)

    Reagan, M. T.; Kowalsky, M B.; Moridis, G. J.; Silpngarmlert, S.

    2010-05-01

    The quantity of hydrocarbon gases trapped in natural hydrate accumulations is enormous, leading to significant interest in the evaluation of their potential as an energy source. Large volumes of gas can be readily produced at high rates for long times from methane hydrate accumulations in the permafrost by means of depressurization-induced dissociation combined with conventional technologies and horizontal or vertical well configurations. Initial studies on the possibility of natural gas production from permafrost hydrates assumed homogeneity in intrinsic reservoir properties and in the initial condition of the hydrate-bearing layers (either due to the coarseness of the model or due to simplifications in the definition of the system). These results showed great promise for gas recovery from Class 1, 2, and 3 systems in the permafrost. This work examines the consequences of inevitable heterogeneity in intrinsic properties, such as in the porosity of the hydrate-bearing formation, or heterogeneity in the initial state of hydrate saturation. Heterogeneous configurations are generated through multiple methods: (1) through defining heterogeneous layers via existing well-log data, (2) through randomized initialization of reservoir properties and initial conditions, and (3) through the use of geostatistical methods to create heterogeneous fields that extrapolate from the limited data available from cores and well-log data. These extrapolations use available information and established geophysical methods to capture a range of deposit properties and hydrate configurations. The results show that some forms of heterogeneity, such as horizontal stratification, can assist in production of hydrate-derived gas. However, more heterogeneous structures can lead to complex physical behavior within the deposit and near the wellbore that may obstruct the flow of fluids to the well, necessitating revised production strategies. The need for fine discretization is crucial in all cases to

  4. DEFLECTION OF A HETEROGENEOUS WIDE-BEAM UNDER UNIFORM PRESSURE LOAD

    SciTech Connect (OSTI)

    T. V. Holschuh; T. K. Howard; W. R. Marcum

    2014-07-01

    Oregon State University (OSU) and the Idaho National Laboratory (INL) are currently collaborating on a test program which entails hydro-mechanical testing of a generic plate type fuel element, or generic test plate assembly (GTPA), for the purpose of qualitatively demonstrating mechanical integrity of uranium-molybdenum monolithic plates as compared to that of uranium aluminum dispersion, and aluminum fuel plates onset by hydraulic forces. This test program supports ongoing work conducted for/by the Global Threat Reduction Initiative (GTRI) Fuels Development Program. This study’s focus supports the ongoing collaborative effort by detailing the derivation of an analytic solution for deflection of a heterogeneous plate under a uniform, distributed load in order to predict the deflection of test plates in the GTPA. The resulting analytical solutions for three specific boundary condition sets are then presented against several test cases of a homogeneous plate. In all test cases considered, the results for both homogeneous and heterogeneous plates are numerically identical to one another, demonstrating correct derivation of the heterogeneous solution. Two additional problems are presents herein that provide a representative deflection profile for the plates under consideration within the GTPA. Furthermore, qualitative observations are made about the influence of a more-rigid internal fuel-meat region and its influence on the overall deflection profile of a plate. Present work is being directed to experimentally confirm the analytical solution’s results using select materials.

  5. Adaptive multi-grid method for a periodic heterogeneous medium in 1-D

    SciTech Connect (OSTI)

    Fish, J.; Belsky, V.

    1995-12-31

    A multi-grid method for a periodic heterogeneous medium in 1-D is presented. Based on the homogenization theory special intergrid connection operators have been developed to imitate a low frequency response of the differential equations with oscillatory coefficients. The proposed multi-grid method has been proved to have a fast rate of convergence governed by the ratio q/(4-q), where oheterogeneity. An adaptive multiscale computational scheme is developed. By this technique a computational model entirely constructed on the scale of material heterogeneity is only used where it is necessary to do so, or as indicated by so called Microscale Reduction Error (MRE) indicators, while in the remaining portion of the problem domain, the medium is treated as homogeneous with effective properties. Such a posteriori MRE indicators and estimators are developed on the basis of assessing the validity of two-scale asymptotic expansion.

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

    SciTech Connect (OSTI)

    Fabio H. Ribeiro

    2011-06-05

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

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

    SciTech Connect (OSTI)

    Jacobs, Gary

    2014-01-31

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

  8. Bedload sheets in heterogeneous sediment

    SciTech Connect (OSTI)

    Whiting, P.J.; Dietrich, W.E.; Leopold, L.B.; Drake, T.G.; Shreve, R.L.

    1988-02-01

    Field observations in streams with beds of coarse sand and fine gravel have revealed that bedload moves primarily as thin, migrating accumulations of sediment, and coarse grains cluster at their leading edge. These accumulations are one or two coarse grains high and are much longer (0.2-0.6 m long in sand; 0.5-2.0 m in fine gravel) than their height. The authors propose the term bedload sheet for these features, and the authors argue that they result from an instability inherent to bedload movement of moderately and poorly sorted sediment. In essence, coarse particles in the bedload slow or stop each other, trap finer particles in their interstices, and thus cause the coarse particles to become mobile again. Bedload sheets develop on the stoss side of dunes, causing the dune to advance incrementally with the arrival of each sheet. Successive deposition of coarse sediment from the leading edge followed by fine sediment may generate the grain-size sorting that distinguishes cross-bedding. Available flume experiments and field observations indicate that bedload sheets are a common, but generally unrecognized, feature of heterogeneous sediment transport.

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

    SciTech Connect (OSTI)

    James F. Haw

    2008-06-28

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

  10. Low-Temperature Hydrocarbon/CO Oxidation Catalysis in Support of HCCI Emission Control

    Broader source: Energy.gov [DOE]

    Development of catalyst materials to facilitate the low-temperature oxidation of hydrocarbons and CO in homogeneous charge compression ignition (HCCI) emissions.

  11. Heterogeneous Recycling in Fast Reactors

    SciTech Connect (OSTI)

    Forget, Benoit; Pope, Michael; Piet, Steven J.; Driscoll, Michael

    2012-07-30

    Current sodium fast reactor (SFR) designs have avoided the use of depleted uranium blankets over concerns of creating weapons grade plutonium. While reducing proliferation risks, this restrains the reactor design space considerably. This project will analyze various blanket and transmutation target configurations that could broaden the design space while still addressing the non-proliferation issues. The blanket designs will be assessed based on the transmutation efficiency of key minor actinide (MA) isotopes and also on mitigation of associated proliferation risks. This study will also evaluate SFR core performance under different scenarios in which depleted uranium blankets are modified to include minor actinides with or without moderators (e.g. BeO, MgO, B4C, and hydrides). This will be done in an effort to increase the sustainability of the reactor and increase its power density while still offering a proliferation resistant design with the capability of burning MA waste produced from light water reactors (LWRs). Researchers will also analyze the use of recycled (as opposed to depleted) uranium in the blankets. The various designs will compare MA transmutation efficiency, plutonium breeding characteristics, proliferation risk, shutdown margins and reactivity coefficients with a current reference sodium fast reactor design employing homogeneous recycling. The team will also evaluate the out-of-core accumulation and/or burn-down rates of MAs and plutonium isotopes on a cycle-by-cycle basis. This cycle-by-cycle information will be produced in a format readily usable by the fuel cycle systems analysis code, VISION, for assessment of the sustainability of the deployment scenarios.

  12. Homogeneous charge engines -- Basis of cyclic variations. Final report

    SciTech Connect (OSTI)

    Whitelaw, J.H.

    1997-06-30

    The objectives of the Grant required investigations of cyclic variations in a homogeneous-charge engine initially with gas combustion and the air from ranging from near quiescent to the incorporation of swirl and tumble by valve inserts. Later experiments were performed with unleaded gasoline. The measurements included local velocity and cylinder pressure through the four strokes of a single-cylinder engine, under motored and firing conditions and with examination of the flame kernel growth by combinations of photography and flame-ionization gauges. In all cases, the measurements of in-cylinder characteristics were linked to performance as measured in terms of speed and its variability, load and emissions. The experiments progressed to consider deviations from homogeneous charge and included consideration of stratified charge with local injection of a rich mixture in the vicinity of the spark gap so as to establish a flame kernel which would propagate securely into an overall weak mixture.

  13. Apparatus for unilateral generation of a homogeneous magnetic field

    DOE Patents [OSTI]

    Fukushima, Eiichi; Rath, Alan R.; Roeder, Stephen B. W.

    1988-01-01

    An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coil in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

  14. Apparatus for unilateral generation of a homogeneous magnetic field

    DOE Patents [OSTI]

    Fukushima, E.; Rath, A.R.; Roeder, S.B.W.

    1984-05-01

    An apparatus for unilaterally producing a substantially homogeneous magnetic field. The apparatus includes two circular electromagnet coils, a small coil and a large coil, which are coaxial with one another and which are separated by a distance equal to one-half the difference in the radius of the two coils. By appropriate selection of electrical currents, which are passed through the coils in opposite directions, a region of homogeneous magnetic field is formed. This region is centered on the common axis of the two coils, at a point on the axis which is at a distance from the small coil equal to one-half the radius of the small coil, and which is on the opposite side of the small coil from the large coil. The apparatus has particular application in the field of diagnostic medical NMR and other NMR applications.

  15. Simulator for SUPO, a Benchmark Aqueous Homogeneous Reactor (AHR)

    SciTech Connect (OSTI)

    Klein, Steven Karl; Determan, John C.

    2015-10-14

    A simulator has been developed for SUPO (Super Power) an aqueous homogeneous reactor (AHR) that operated at Los Alamos National Laboratory (LANL) from 1951 to 1974. During that period SUPO accumulated approximately 600,000 kWh of operation. It is considered the benchmark for steady-state operation of an AHR. The SUPO simulator was developed using the process that resulted in a simulator for an accelerator-driven subcritical system, which has been previously reported.

  16. High load operation in a homogeneous charge compression ignition engine

    SciTech Connect (OSTI)

    Duffy, Kevin P.; Kieser, Andrew J.; Liechty, Michael P.; Hardy, William L.; Rodman, Anthony; Hergart, Carl-Anders

    2008-12-23

    A homogeneous charge compression ignition engine is set up by first identifying combinations of compression ratio and exhaust gas percentages for each speed and load across the engines operating range. These identified ratios and exhaust gas percentages can then be converted into geometric compression ratio controller settings and exhaust gas recirculation rate controller settings that are mapped against speed and load, and made available to the electronic

  17. HYPERSONIC BUCKSHOT: ASTROPHYSICAL JETS AS HETEROGENEOUS COLLIMATED PLASMOIDS

    SciTech Connect (OSTI)

    Yirak, Kristopher; Frank, Adam; Cunningham, Andrew J.; Mitran, Sorin

    2009-04-20

    Herbig-Haro jets are commonly thought of as homogeneous beams of plasma traveling at hypersonic velocities. Structure within jet beams is often attributed to periodic or 'pulsed' variations of conditions at the jet source. Simulations based on this scenario result in knots extending across the jet diameter. Observations and recent high energy density laboratory experiments shed new light on structures below this scale and indicate they may be important for understanding the fundamentals of jet dynamics. In this paper, we offer an alternative to 'pulsed' models of protostellar jets. Using direct numerical simulations we explore the possibility that jets are chains of subradial clumps propagating through a moving interclump medium. Our models explore an idealization of this scenario by injecting small (r < r {sub jet}), dense ({rho}>{rho}{sub jet}) spheres embedded in an otherwise smooth interclump jet flow. The spheres are initialized with velocities differing from the jet velocity by {approx}15%. We find that the consequences of shifting from homogeneous to heterogeneous flows are significant as clumps interact with each other and with the interclump medium in a variety of ways. Structures which mimic what is expected from pulsed-jet models can form, as can be previously unseen, 'subradial' behaviors including backward facing bow shocks and off-axis working surfaces. While these small-scale structures have not been seen before in simulation studies, they are found in high-resolution jet observations. We discuss implications of our simulations for the interpretation of protostellar jets with regard to characterization of knots by a 'lifetime' or 'velocity history' approach as well as linking observed structures with central engines which produce the jets.

  18. Environment-based pin-power reconstruction method for homogeneous core calculations

    SciTech Connect (OSTI)

    Leroyer, H.; Brosselard, C.; Girardi, E.

    2012-07-01

    Core calculation schemes are usually based on a classical two-step approach associated with assembly and core calculations. During the first step, infinite lattice assemblies calculations relying on a fundamental mode approach are used to generate cross-sections libraries for PWRs core calculations. This fundamental mode hypothesis may be questioned when dealing with loading patterns involving several types of assemblies (UOX, MOX), burnable poisons, control rods and burn-up gradients. This paper proposes a calculation method able to take into account the heterogeneous environment of the assemblies when using homogeneous core calculations and an appropriate pin-power reconstruction. This methodology is applied to MOX assemblies, computed within an environment of UOX assemblies. The new environment-based pin-power reconstruction is then used on various clusters of 3x3 assemblies showing burn-up gradients and UOX/MOX interfaces, and compared to reference calculations performed with APOLLO-2. The results show that UOX/MOX interfaces are much better calculated with the environment-based calculation scheme when compared to the usual pin-power reconstruction method. The power peak is always better located and calculated with the environment-based pin-power reconstruction method on every cluster configuration studied. This study shows that taking into account the environment in transport calculations can significantly improve the pin-power reconstruction so far as it is consistent with the core loading pattern. (authors)

  19. Bis(monoacylglycero)phosphate and ganglioside GM1 spontaneously form small homogeneous vesicles at specific concentrations

    SciTech Connect (OSTI)

    Chebukati, Janetricks N.; Goff, Philip C.; Frederick, Thomas E.; Fanucci, Gail E.

    2010-04-09

    The morphology and size of hydrated lipid dispersions of bis(monoacylglycero)phosphate (BMP) mixed with varying mole percentages of the ganglioside GM1 were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Electron paramagnetic resonance (EPR) spectroscopy of these same mixtures, doped at 0.5 mol% with doxyl labeled lipids, was used to investigate acyl-chain packing. Results show that for 20-30% GM1, hydrated BMP:GM1 mixtures spontaneously form small spherical vesicles with diameters {approx}100 nm and a narrow size distribution profile. For other concentrations of GM1, hydrated dispersions with BMP have non-spherical shapes and heterogeneous size profiles, with average vesicle diameters >400 nm. All samples were prepared at pH 5.5 to mimic the lumen acidity of the late endosome where BMP is an essential component of intraendosomal vesicle budding, lipid sorting and trafficking. These findings indicate that GM1 and BMP under a limited concentration range spontaneously form small vesicles of homogeneous size in an energy independent manner without the need of protein templating. Because BMP is essential for intraendosomal vesicle formation, these results imply that lipid-lipid interactions may play a critical role in the endosomal process of lipid sorting and trafficking.

  20. Multicomponent homogeneous alloys and method for making same

    DOE Patents [OSTI]

    Dutta, Partha S.; Miller, Thomas R.

    2003-09-02

    The present application discloses a method for preparing a homogeneous ternary or quaternary alloy from a quaternary melt. The method includes providing a family of phase diagrams for the quaternary melt which shows (i) composition/temperature data, (ii) tie lines connecting equilibrium liquid and solid compositions, and (iii) isotherms representing boundaries of a miscibility gap. Based on the family of phase diagrams, a quaternary melt composition and an alloy growth temperature is selected. A quaternary melt having the selected quaternary melt composition is provided and a ternary or quaternary alloy is grown from the quaternary melt at the selected alloy growth temperature. A method for making homogeneous ternary or quaternary alloy from a ternary or quaternary melt is also disclosed, as are homogeneous quaternary single-crystal alloys which are substantially free from crystal defects and which have the formula A.sub.x B.sub.1-x C.sub.y D.sub.1-y, x and y being the same or different and in the range of 0.001 to 0.999.

  1. Linkage heterogeneity among 59 Dutch hereditary breast cancer families

    SciTech Connect (OSTI)

    Cornelis, R.S.; Vliet, M. van; Leeuwen, I. van

    1994-09-01

    We have investigated 59 Dutch kindreds with at least three first-degree relatives with breast and/or ovarian cancer for linkage to BRCA1 on 17q12-q21, using at least 4 microsatellite markers flanking BRCA1 on either side. Assuming no heterogeneity, the overall multipoint lod score in this group of families was -7.59. A marked clustering of lod scores >0.5 was observed among the 13 families with a mean age of onset lower than 45 (total lod score: +3.36). Among the 8 kindreds with a mean age of onset lower than 45 and {ge}3 cases diagnosed under 45, the lod score was +4.43. Interestingly, most of the evidence against linkage was found in 17 families with a mean age of onset between 45 and 54 (total lod score of -8.72). It was estimated that 28% of the breast-only families might be caused by BRCA1. Over the 16 breast-ovarian cancer families a lod score of -3.78 was obtained under homogeneity. The highest lod score was +0.57, assuming heterogeneity with 33% of the families being linked to BRCA1. One family gave a multipoint lod score of -2.01 and thereby satisfies the conventional criterion of an unlinked family. Our results support the conclusions from earlier work by others, namely that BRCA1 predisposes particularly to early-onset breast cancer. The proportion of breast-ovarian cancer families we found linked to BRCA1 is much lower than that found by the Breast Cancer Linkage Consortium. This might be caused by the single unlinked family against an insufficient number of families able to give conclusive positive lod scores.

  2. Ganglion dynamics of Supercritical CO2 in heterogeneous media...

    Office of Scientific and Technical Information (OSTI)

    Ganglion dynamics of Supercritical CO2 in heterogeneous media. Citation Details In-Document Search Title: Ganglion dynamics of Supercritical CO2 in heterogeneous media. Abstract ...

  3. Controlling And Operating Homogeneous Charge Compression Ignition (Hcci) Engines

    SciTech Connect (OSTI)

    Flowers, Daniel L.

    2005-08-02

    A Homogeneous Charge Compression Ignition (HCCI) engine system includes an engine that produces exhaust gas. A vaporization means vaporizes fuel for the engine an air induction means provides air for the engine. An exhaust gas recirculation means recirculates the exhaust gas. A blending means blends the vaporized fuel, the exhaust gas, and the air. An induction means inducts the blended vaporized fuel, exhaust gas, and air into the engine. A control means controls the blending of the vaporized fuel, the exhaust gas, and the air and for controls the inducting the blended vaporized fuel, exhaust gas, and air into the engine.

  4. Exhaust gas recirculation in a homogeneous charge compression ignition engine

    SciTech Connect (OSTI)

    Duffy, Kevin P.; Kieser, Andrew J.; Rodman, Anthony; Liechty, Michael P.; Hergart, Carl-Anders; Hardy, William L.

    2008-05-27

    A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

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

    DOE Patents [OSTI]

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

    2015-05-19

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

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

    SciTech Connect (OSTI)

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

    2015-10-07

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

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

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

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

    2015-10-07

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

  8. Heterogeneity and Scaling in Geologic Media

    SciTech Connect (OSTI)

    Gregory N. Boitnott; Gilles Y. Bussod; Paul N. Hagin; Stephen R. Brown

    2005-04-18

    The accurate characterization and remediation of contaminated subsurface environments requires the detailed knowledge of subsurface structures and flow paths. Enormous resources are invested in scoping and characterizing sites using core sampling, 3-D geophysical surveys, well tests, etc.... Unfortunately, much of the information acquired is lost to compromises and simplifications made in constructing numerical grids for the simulators used to predict flow and transport from the contaminated area to the accessible environment. In rocks and soils, the bulk geophysical and transport properties of the matrix and of fracture systems are determined by the juxtaposition of geometric features at many length scales. In the interest of computational efficiency, recognized heterogeneities are simplified, averaged out, or entirely ignored in spite of recent studies that recognize that: (1) Structural and lithologic heterogeneities exist on all scales in rocks. (2) Small heterogeneities influence, and can control the physical and chemical properties of rocks. In this work we propose a physically based approach for the description and treatment of heterogeneities, that highlights the use of laboratory equipment designed to measure the effect on physical properties of fine scale heterogeneities observed in rocks and soils. We then discuss the development of an integration methodology that uses these measurements to develop and upscale flow and transport models. Predictive simulations are 'calibrated' to the measured heterogeneity data, and subsequently upscaled in a way that is consistent with the transport physics and the efficient use of environmental geophysics. This methodology provides a more accurate interpretation and representation of the subsurface for both environmental engineering and remediation. We show through examples, (i) the important influence of even subtle heterogeneity in the interpreting of geophysical data, and (ii) how physically based upscaling can lead

  9. Proton Mediated Chemistry and Catalysis in a Self-Assembled Supramolecular Host

    SciTech Connect (OSTI)

    Pluth, Michael; Bergman, Robert; Raymond, Kenneth

    2009-04-10

    Synthetic supramolecular host assemblies can impart unique reactivity to encapsulated guest molecules. Synthetic host molecules have been developed to carry out complex reactions within their cavities, despite the fact that they lack the type of specifically tailored functional groups normally located in the analogous active sites of enzymes. Over the past decade, the Raymond group has developed a series of self-assembled supramolecules and the Bergman group has developed and studied a number of catalytic transformations. In this Account, we detail recent collaborative work between these two groups, focusing on chemical catalysis stemming from the encapsulation of protonated guests and expanding to acid catalysis in basic solution. We initially investigated the ability of a water-soluble, self-assembled supramolecular host molecule to encapsulate protonated guests in its hydrophobic core. Our study of encapsulated protonated amines revealed rich host-guest chemistry. We established that self-exchange (that is, in-out guest movement) rates of protonated amines were dependent on the steric bulk of the amine rather than its basicity. The host molecule has purely rotational tetrahedral (T) symmetry, so guests with geminal N-methyl groups (and their attendant mirror plane) were effectively desymmetrized; this allowed for the observation and quantification of the barriers for nitrogen inversion followed by bond rotation. Furthermore, small nitrogen heterocycles, such as N-alkylaziridines, N-alkylazetidines, and N-alkylpyrrolidines, were found to be encapsulated as proton-bound homodimers or homotrimers. We further investigated the thermodynamic stabilization of protonated amines, showing that encapsulation makes the amines more basic in the cavity. Encapsulation raises the effective basicity of protonated amines by up to 4.5 pK{sub a} units, a difference almost as large as that between the moderate and strong bases carbonate and hydroxide. The thermodynamic stabilization

  10. Crystallization in supercooled liquid Cu: Homogeneous nucleation and growth

    SciTech Connect (OSTI)

    E, J. C.; Wang, L.; Luo, S. N.; Cai, Y.; Wu, H. A.

    2015-02-14

    Homogeneous nucleation and growth during crystallization of supercooled liquid Cu are investigated with molecular dynamics simulations, and the microstructure is characterized with one- and two-dimensional x-ray diffraction. The resulting solids are single-crystal or nanocrystalline, containing various defects such as stacking faults, twins, fivefold twins, and grain boundaries; the microstructure is subject to thermal fluctuations and extent of supercooling. Fivefold twins form via sequential twinning from the solid-liquid interfaces. Critical nucleus size and nucleation rate at 31% supercooling are obtained from statistical runs with the mean first-passage time and survival probability methods, and are about 14 atoms and 10{sup 32} m{sup −3}s{sup −1}, respectively. The bulk growth dynamics are analyzed with the Johnson-Mehl-Avrami law and manifest three stages; the Avrami exponent varies in the range of 1–19, which also depends on thermal fluctuations and supercooling.