Download or read book Ab Initio DFT Modeling of the Oxidation of Methane on Transition Metal Catalysts written by George Psofogiannakis and published by . This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AB Initio Study of Organometallic Phthalocyanine Catalysts for the Conversion of Methane to Methanol written by Chase Ferrone and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methane’s low energy density and contribution to the greenhouse gas effect has emphasized the importance of converting methane to methanol. In this work, organometallic, single transition metal active site heterogeneous phthalocyanine catalysts have been designed to activate methane in a single step process. Copper and cobalt phthalocyanines, supported by TiN and BN substrates, have been studied using ab initio density functional theory (DFT) implemented in the Vienna ab initio software package (VASP). Titanium nitride (TiN) has potential as a substrate due to its metallic-like behavior and favorable optical properties.

Download or read book Ab Initio Study of Co Oxidation Reaction on Transition Metal Catalysts written by Ihsan Atiyeh Ata Erikat and published by . This book was released on 2008 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transition State Modeling for Catalysis written by Donald G. Truhlar and published by . This book was released on 1999 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains the latest research on the applications of computational chemistry, computational biochemistry, and computational physics to the new field of direct modeling of transition states for catalytic reactions. It includes all types of catalysts: organometals, metals and metalloids, metal oxides and zeolites, and enzymes.

Download or read book Developing Methods to Inform Catalyst Design for the Electrochemical Oxidation of Methane and Alcohols written by Michael James Boyd and published by . This book was released on 2021 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the production of natural gas and agricultural biomass/energy crops increases, new efficient and sustainable technologies will be required to convert these feedstock molecules into the same fuels and chemical we get from conventional petroleum today. Electrochemistry is a possible tool for the conversion of these species that can be coupled to renewable electricity. The discovery and development of selective and active electrocatalysts is one of the primary challenges in utilizing natural gas and biomass resources. But first there is a lack of fundamental understanding in (1) the reaction mechanism and (2) how operating conditions such as potential, electrolyte pH, mass transport, and time affect the the activity and selectivity of catalysts. To this end platinum was used as a model system to study electrochemical methane oxidation at room temperature and pressure. The experimental results on platinum combined with density functional theory calculations show that methane is first thermally activated at Pt (211) like step sites, then the resulting methyl intermediate is electrochemically oxidized to CO* which is in equilibrium with the final product CO2. The equilibrium can be shifted to favor complete oxidation by adjusting the applied electrochemical potential, specifically at potentials below 0.5 V vs. RHE CO* is the most thermodynamically stable species along the reaction pathway whereas above 0.5 V vs. RHE CO2 is now the most stable species. Important to note however is that since the kinetics for methane activation are very slow (barrier of ~0.95 eV) the platinum surface must be free of other adsorbed species, namely protons or hydroxides. Based on reaction mechanism for electrochemical methane oxidation on platinum it is unlikely that partial oxidation of methane on metallic electrodes well occur. For this reason we probed the activity of several transition metal oxide materials with the hope that they may be active for methane oxidation. Unfortunately our initial results suggest no significant methane oxidation occurs on these materials. In the case of biomass oxidation 1st row transition metal oxides have recently been shown to be quite selective in the conversion of alcohols to their corresponding carboxylic acids. Benzyl alcohol was used as a model molecule to study the reaction mechanism for alcohol oxidation on Ni(OH)2 electrodes as a function of potential and electrolyte pH. It was found that the active phase for alcohol oxidation is the metal oxy-hydroxide. The activity and selectivity were found to be heavily dependent on the electrolyte pH. Under strong alkaline conditions (> pH 13) high current densities and complete oxidation of benzyl alcohol to benzoate was favored whereas at more moderately alkaline conditions low current densities and partial oxidation to benzaldehyde was favored. Based on these results we hypothesize that a significant concentration of OH- in solution is required to activated the intermediate product benzaldehyde. The activity of several novel Ni materials was also probed for benzyl alcohol oxidation. Ni-doped nitrided carbons which have single atom nickel active sites were found to be selective for partial oxidation, however further optimization of the catalyst synthesis is required to increase the activity to compete with the bulk Ni(OH)2 electrodes. In conclusion, this dissertation presents a variety of experimental work focused on identifying the reaction mechanism for several oxidation reactions and provides key understanding that can be used towards the development of new electrocatalysts for the oxidation of hydrocarbons and alcohols.

Download or read book Multiscale Modeling of Oxidation and Reduction Chemistry on Transition Metal Oxides written by Minkyu Kim (Ph. D. in chemical engineering) and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal catalysts, including platinum, palladium, and etc., are widely used in oxygen rich applications such as catalytic combustion of natural gas in lean gas turbine, exhaust gas remediation in automobiles and power generation. Under such processes, several different oxygen phases can potentially grow on the surface. The reactivity of such oxygen phases can be dramatically different and therefore there is a need to understand both the oxygen phase that exists under reaction conditions and the reactivity of such oxygen phases. To understand reactivity and stability of important transition metal oxide surfaces including PdO(101), RuO2(110), and IrO2(110), we investigated surface chemistry including thermal reduction, CO and alkane oxidation over those surfaces by using multiscale modeling approach compared with surface science experiments. This approach is based on developing kinetic Monte Carlo (kMC) models based on DFT calculations of the elementary steps occurring on the surface. The DFT based kMC simulations allow us to elucidate the role of various mechanisms on the overall reactivity of the surfaces under low and ambient pressures, and reaction conditions.

Download or read book Transition Metal Doped Rare earth Metal Oxide Catalysts for Dry Reforming of Methane written by Bo Li and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dry reforming of methane (DRM) is an environment-friendly and sustainable chemical technique, since it converts methane and CO2, two most abundant greenhouse gases, into syngas and other high value chemical products. The most common catalyst for DRM reaction is Ni due to its low cost and high catalytic activity but Ni-based catalysts undergo severe deactivation due to coking. transition metal (TM) doped rare earth oxide catalysts have shown promise in the high catalytic activity and coking resistance ability. This thesis applies the first principles calculation method to design Ni and Zr doped CeO2 catalyst model. Density functional theory (DFT+U) method is used to generate the structure-composition-stability relationships. The distribution of Zr with multiple concentrations have been studied in the CeO2 fluorite lattice. The oxygen vacancy effect has also been examined in the bulk and surface Ni-doped CeO2 bulk and surface structure to determine the most stable configuration. The surface chemistry study of Ni-doped CeO2 surface shows that hydrocarbon over the surface is always oxidized and prefers bonding to the oxygen site rather than the Ni site. This result can thermodynamically explain the reason of catalyst coking resistance.

Download or read book Chemical Modelling written by Royal Society of Chemistry (Great Britain) and published by Royal Society of Chemistry. This book was released on 2000 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical Modelling: Applications and Theory comprises critical literature reviews of molecular modelling, both theoretical and applied. Molecular modelling in this context refers to modelling the structure, properties and reactions of atoms, molecules & materials. Each chapter is compiled by experts in their fields and provides a selective review of recent literature. With chemical modelling covering such a wide range of subjects, this Specialist Periodical Report serves as the first port of call to any chemist, biochemist, materials scientist or molecular physicist needing to acquaint themselves of major developments in the area. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading authorities in the relevant subject areas, the series creates a unique service for the active research chemist, with regular, in-depth accounts of progress in particular fields of chemistry. Subject coverage within different volumes of a given title is similar and publication is on an annual or biennial basis. Current subject areas covered are Amino Acids, Peptides and Proteins, Carbohydrate Chemistry, Catalysis, Chemical Modelling. Applications and Theory, Electron Paramagnetic Resonance, Nuclear Magnetic Resonance, Organometallic Chemistry. Organophosphorus Chemistry, Photochemistry and Spectroscopic Properties of Inorganic and Organometallic Compounds. From time to time, the series has altered according to the fluctuating degrees of activity in the various fields, but these volumes remain a superb reference point for researchers.

Download or read book Transition Metals in Coordination Environments written by Ewa Broclawik and published by Springer. This book was released on 2019-03-16 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the electronic properties of transition metals in coordination environments. These properties are responsible for the unique and intricate activity of transition metal sites in bio- and inorganic catalysis, but also pose challenges for both theoretical and experimental studies. Written by an international group of recognized experts, the book reviews recent advances in computational modeling and discusses their interplay using experiments. It covers a broad range of topics, including advanced computational methods for transition metal systems; spectroscopic, electrochemical and catalytic properties of transition metals in coordination environments; metalloenzymes and biomimetic compounds; and spin-related phenomena. As such, the book offers an invaluable resource for all researchers and postgraduate students interested in both fundamental and application-oriented research in the field of transition metal systems.

Download or read book Methane Activation on Supported Transition Metal Catalysts written by Jason Ned Carstens and published by . This book was released on 1997 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computational Catalysis written by Aravind Asthagiri and published by Royal Society of Chemistry. This book was released on 2014 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a comprehensive review of the methods and approaches being adopted to push forward the boundaries of computational catalysis.

Download or read book DFT Modelling of Methane Oxidation with H2O2 Over Heterogeneous Catalysts written by Adam Thetford and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Improved Modeling of Transition Metals Applications to Catalysis and Technetium Chemistry written by T. R. Cundari and published by . This book was released on 2004 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is considerable impetus for identification of aqueous OM catalysts as water is the ultimate ''green'' solvent. In collaboration with researchers at Ames Lab, we investigated effective fragment and Monte Carlo techniques for aqueous-phase hydroformylation (HyF). The Rh of the HyF catalyst is weakly aquated, in contrast to the hydride of the Rh-H bond. As the insertion of the olefin C=C into Rh-H determines the linear-to-branched aldehyde ratio, it is reasonable to infer that solvent plays an important role in regiochemistry. Studies on aqueous-phase organometallic catalysis were complemented in studies of the gas-phase reaction. A Rh-carbonyl-phosphine catalyst was investigated. Two of the most important implications of this research include (a) pseudorotation among five-coordinate intermediates is significant in HyF, and (b) CO insertion is the rate-determining step. The latter is in contrast to experimental deductions, highlighting the need for more accurate modeling. To this end, we undertook studies of (a) experimentally relevant PR{sub 3} co-ligands (PMe{sub 3}, PPh{sub 3}, P(p-PhSO{sub 3{sup -}}){sub 3}, etc.), and (b) HyF of propene. For the propylene research, simulations indicated that the linear: branched aldehyde ratio (linear is more desirable) is determined by thermodynamic discrimination of two distinct pathways. Other projects include a theory-experiment study of C-H activation by early transition metal systems, which establishes that weakly-bound adducts play a key role in activity selectivity. By extension, more selective catalysts for functionalization of methane (major component of natural gas) will require better understanding of these adducts, which are greatly affected by steric interactions with the ligands. In the de novo design of Tc complexes, we constructed (and are now testing) a coupled quantum mechanics-molecular mechanics protocol. Initial research shows it to be capable of accurately predicting structure ''from scratch.'' Challenges include conformational, geometric, coordination, spin, and particularly linkage (e.g., Tc-SCN versus Tc-NCS) isomerism. In general, our protocol can rapidly (

Download or read book CO2 A Valuable Source of Carbon written by Marcello De De Falco and published by Springer Science & Business Media. This book was released on 2013-07-30 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the annual production of carbon Dioxide (CO2) reaches 30 billion tones, the growing issue of the greenhouse effect has triggered the development of technologies for CO2 sequestration, storage and use as a reactant. Collecting together the reports of the Congress at University of Rome (Campus Bio-medico) held 16th April 2012, CO2: A Valuable Source of Carbon presents and discusses promising technologies for the industrial exploitation of CO2. Divided into two parts, the current technology is evaluated and summarized before European and national projects are presented. The focus on CO2 recovery, particularly in value-added production, proposes applicable methods to develop sustainable practices and even to mitigate greenhouse gas emission from large-scale fossil fuels usage. Including current data and real-world examples, CO2: A valuable source of carbon provides students, engineers, researchers and industry professional with up-to-date material and potential areas for development and research.

Download or read book Computational Approaches for Studying Enzyme Mechanism Part A written by and published by Academic Press. This book was released on 2016-08-04 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Approaches for Studying Enzyme Mechanism Part A, is the first of two volumes in the Methods in Enzymology series, focusses on computational approaches for studying enzyme mechanism. The serial achieves the critically acclaimed gold standard of laboratory practices and remains one of the most highly respected publications in the molecular biosciences. Each volume is eagerly awaited, frequently consulted, and praised by researchers and reviewers alike. Now with over 550 volumes, the series remains a prominent and essential publication for researchers in all fields of life sciences and biotechnology, including biochemistry, chemical biology, microbiology, synthetic biology, cancer research, and genetics to name a few. - Focuses on computational approaches for studying enzyme mechanism - Continues the legacy of this premier serial with quality chapters authored by leaders in the field - Covers research methods in intermediate filament associated proteins, and contains sections on such topics as lamin-associated proteins, intermediate filament-associated proteins and plakin, and other cytoskeletal cross-linkers

Download or read book 30th European Symposium on Computer Aided Chemical Engineering written by Sauro Pierucci and published by Elsevier. This book was released on 2020-10-23 with total page 2119 pages. Available in PDF, EPUB and Kindle. Book excerpt: 30th European Symposium on Computer Aided Chemical Engineering, Volume 47 contains the papers presented at the 30th European Symposium of Computer Aided Process Engineering (ESCAPE) event held in Milan, Italy, May 24-27, 2020. It is a valuable resource for chemical engineers, chemical process engineers, researchers in industry and academia, students, and consultants for chemical industries. - Presents findings and discussions from the 30th European Symposium of Computer Aided Process Engineering (ESCAPE) event - Offers a valuable resource for chemical engineers, chemical process engineers, researchers in industry and academia, students, and consultants for chemical industries

Download or read book Mechanisms and Microkinetic Modeling of CO2 Conversions on Multi functional Catalysts written by Narges Manavi and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our heavy dependence on fossil fuels allows a large amount of CO2 to be directly emitted into the atmosphere. There is strong evidence that the rise of atmospheric CO2 level causes a cascade of severe environmental issues such as ocean acidification, sea level rises, long drought, and intense heat waves. This thesis explores relevant catalysis technologies that will transform CO2 into a building block species for chemicals production. Catalytic CO2 utilization faces major limitations because of the chemical stability of this molecule. Multiple technologies such as dry reforming of methane (DRM) and CO2 hydrogenation have demonstrated their technological and economical potentials to overcome CO2 conversion's limitations. Yet, the catalysis science and technology for CO2 utilization is far from mature. Effective and affordable catalysts suitable for industrial-scale applications are not readily available. Fundamentally, the catalytic reactivities of simple mono-functional catalysts are limited by the so-called Sabatier principle. Moreover, the best performing catalysts often rely on expensive noble metals. Catalyst discovery and design have shifted focus toward composite, bifunctional materials manufactured from earth-abundant elements. Breakthroughs have already been made in ammonia synthesis, CO oxidation, water-gas-shift reaction, and hydrogen production reactions. DRM converts CO2 and CH4 (both are potent greenhouse gases) into syngas, a versatile industrial mixture. Currently, DRM catalysts are challenged by inadequate reactivity and short lifetime. In this thesis, systematic investigations were carried out to understand the mechanistic origin of DRM on the dual-site models representative of real-life bifunctional catalysts. An unconventional material, Co3Mo3N (a ternary nitride), was the focus in this study. Earlier experimental studies indicated that Co3Mo3N is active and durable, but the source of its reactivity and stability remain unclear. The adsorptions, desorption, and surface reactions of DRM intermediates on the Co3Mo3N (111) facet were investigated using the quantum mechanical density functional theory (DFT) method. The site preferences and DRM pathways on Co3Mo3N are revealed for the first time regarding this catalytic material. My work yielded clear evidence that Co3Mo3N promotes CH4 activation and the oxidations of surface carbonaceous species at its Co site and Co-Mo2N boundary site, respectively. DFT calculations further showed that, due to the presence of two distinct sites, the OH and CHO intermediates that appear during DRM do not obey the linear scaling relationships, resulting in the oxidation reactions occurring at higher than usual rates. The analyses based on DFT calculations are then corroborated by the mean-field microkinetic modeling (MKM) designed especially for dual-site catalytic systems. My work concluded that bifunctional catalysts containing sites with O affinities are desirable for DRM. The MKM results further clarify that cross-site diffusions of DRM intermediates, i.e., C, O, OH, CO, and CH, play the most prominent role in mitigating coke formation. In addition, solid and liquid Ga containing well-dispersed Ni, Pd, and Ru atoms were modeled for DRM. It was found that Ru trimer embedded in Ga solid solutions yields one of the best H2 production rates. Then, the topological cluster classification (TCC) analyses on ab initio molecular dynamics (AIMD) simulations suggested that the transition metal solutes (e.g., Ni, Pd) dissolved in liquid Ga prefer the liquid-gas interface at low or moderate temperatures. This thesis also considered indium oxide (In2O3) catalysts supported on Zr, Ce, and Pr oxides for methanol production via CO2 hydrogenation. Experimentally, the highest CO2 conversion and CH3OH selectivity were observed on ZrO2-supported In2O3 (Zr-In2O3). DFT calculations revealed that a unique bent configuration of CO2 adsorption at the oxygen vacancy site (O[subscript v]) in Zr-In2O3 stabilizes the formate (HCOO) intermediate. Subsequent hydrogenations of HCOO to CH2O, and then CH3O are also thermodynamically more favorable over Zr-In2O3 than on other oxide catalysts. DFT modeling also showed that the product selectivity depends on the relative activation energies between hydrogenation (for CH3OH formation) and the C-O bond cleavage (for CO formation) of HCOO. This thesis demonstrated the predictive power of DFT in elucidating the complex surface chemistries on bifunctional catalytic materials. Based on the case studies, DFT, coupled with the microkinetic modeling and molecular dynamics simulation techniques, produced highly valuable knowledge that can be elusive for other research tools. More importantly, the theoretical knowledge will allow researchers to continue the pursuit of more efficient and stable catalysts for CO2 utilizations so that we will be better equipped to solve some of the most urgent societal issues.