Download or read book In Situ IR Spectroscopic Studies of the CO Oxidation Reaction Over a Ruthenium Model Catalyst written by Attila Farkas and published by . This book was released on 2008 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In Situ Infared i e Infrared Studies of Catalytic Partial Oxidation written by Chundi Cao and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytic partial oxidation (CPO) has received considerable interest recently both as a way to utilize remote natural gas resources and to provide H[subscript]2 for a fuel cell. Studies on the reactions at lower temperatures and transient conditions were performed, which can provide insights on the mechanism of CPO at high reactions, particularly on the role of the chemical and physical state of the noble metal catalyst. In this work, ignition of methane CPO on Pt/Al[subscript]2O[subscript]3 and Rh/Al[subscript]2O[subscript]3 catalysts and methanol CPO on Pt/Al[subscript]2O[subscript]3 catalysts were studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ignition mechanism study of CH4 on Pt/Al[subscript]2O[subscript]3 showed that oxygen mainly covers the surface until ignition. Competition between the two reactants is assumed. The heat of adsorption of oxygen is a key factor for ignition of the methane partial oxidation reaction on Pt/Al[subscript]2O[subscript]3. The ignition mechanism on Rh/Al[subscript]2O[subscript]3 was found to be different from Pt/Al[subscript]2O[subscript]3. The oxidation state of the catalyst changed significantly as the temperature was raised towards the ignition. An oxidized rhodium state, Rh[superscript]n+, progressively formed as the temperature was increased while Rh[superscript]0 decreased. In addition, a greater amount of Rh[supercript]n+ was found when the oxygen concentration in the feed was higher. From these results, it is hypothesized that ignition of methane CPO on Rh/Al[subscript]2O[subscript]3 is related to the accumulation of the Rh[superscript]n+ state. Dissociation adsorption of methanol occurs on both Al2O3 and Pt/Al[subscript]2O[subscript]3. It is suggested that formate was one of the important intermediates in the reaction pathway. Oxygen species play a key role in the formation of formate on the catalysts, and it also affects the product composition. Formate mainly decomposed into CO, which is the dominant source for CO[subscript]2 production in the reactions at higher temperatures.
Download or read book Plasma Catalysis written by Annemie Bogaerts and published by MDPI. This book was released on 2019-04-02 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.
Download or read book A Ruthenium Water Oxidation Catalyst and Intermediates written by Erin Melissa Duffy and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work focuses on a well-known molecular water oxidation catalyst, [Ru(tpy)(bpy)(OH2)]2, the simplest of a large family of ruthenium-based catalysts. Although there have been numerous chemical investigations of this catalyst's activity in the past decade, direct structural information and corresponding molecular level insight had not been achieved. Presented here are some of the first spectroscopic studies of this catalyst and isolated intermediates of the reaction pathway, where previously proposed molecular structures are confirmed and key intermolecular interactions that influence reactivity are probed First, the [Ru(tpy)(bpy)(OH2)]2 catalyst is investigated in the form of controlled, size-selected water clusters in the gas phase, which simulate the interaction of the catalyst in aqueous solution, its typical operating phase. Using infrared spectroscopy, we probe the OH stretches of the aqua ligand and surrounding water molecules, which elucidates the strength of these interactions. With support from theoretical calculations, we gain insight into structural changes that occur upon solvation. These structural details provide valuable molecular level information about how the catalyst activates water molecules to initiate the catalytic cycle. Next, the first electrochemical intermediate of the catalytic cycle, [Ru(tpy)(bpy)(OH)]2+, is discussed. Similarly to the aforementioned work, we probe key solvent interactions of this species that forms after a one electron, one proton oxidation step. By comparing the results of these experiments to those of the previous study, we learn how the complex's reactivity changes after the first reaction step in the cycle and the implications for its progression through further oxidation steps. Finally, the proposed final intermediate of the water oxidation cycle, [Ru(tpy)(bpy)(O2)]2+, is investigated. This species consists of an O2 molecule bound to the Ru center, and its release as the final reaction product also triggers the regeneration of the initial catalyst. The binding orientation of the O2 moiety had previously been debated due to a lack of experiments that probed this complex directly, and disagreement between the indirect information acquired experimentally and theoretical calculations. Here, we exploit our mass-selective technique and isotopic substitution of O2 to definitively identify the O-O stretch in the far infrared region and confirm the bidentate interaction of O2 with Ru.
Download or read book In situ Spectroscopic Studies of Adsorption at the Electrode and Electrocatalysis written by Shi-Gang Sun and published by Elsevier. This book was released on 2011-08-11 with total page 559 pages. Available in PDF, EPUB and Kindle. Book excerpt: In-Situ Spectroscopic Studies of Adsorption at the Electrode and Electrocatalysis is a new reference on in-situ spectroscopic techniques/applications, fundamentals of electrocatalysis at molecule level, and progresses within electrochemical surface science. Presenting both essential background knowledge at graduate level and original research within the fields of spectroscopy, electrochemistry, and surface science. Featuring 15 chapters by prominent worldwide scholars, based on their recent progress in different aspects of in-situ spectroscopy studies, this book will appeal to a wide audience of scientists. In summary this book is highly suitable for graduates learning basic concepts and advanced applications of in-situ spectroscopy, electrocatalysis and electrode adsorptions.* Written by the most active scientists in the fields of spectroscopy, electrochemistry and surface science* Essential background knowledge for graduate students* A modern reference of cutting-edge scientific research
Download or read book Simultaneous Kinetic and Infrared Studies of Carbon Monoxide Oxidation on Supported Platinum Catalyst written by Kwang-Ho Park and published by . This book was released on 1987 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electrochemical and Transmission Infrared Spectroscopic Studies of Methanol Oxidation Reactions at Platinum and Platinum ruthenium Fuel Cell Catalysts written by Lin Gao and published by . This book was released on 2003 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Spectroscopic Signatures of Pressurized Carbon Dioxide in Diffuse Reflectance Infrared Spectroscopy of Heterogeneous Catalysts written by Samuel M. Fehr and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy to study surface species of reaction intermediates on heterogeneous catalysts requires particular precautions, when assigning IR bands to intermediates apparently resulting from the reaction of H2, CO, and CO2. In accordance with earlier work, it is shown that in the investigation of the heterogeneous methanol synthesis, several gas phase bands of CO2 were misassigned in previous studies as adsorbates on the catalyst surface. Thus, several combination bands and overtones of CO2 in the 2200–750 cm−1 range – notably those at 2130, 2112, 2107, 2094, 2077, ∼2056, 1933, ∼1920, ∼1079, ∼1050, ∼973, and ∼948 cm−1 – were already misinterpreted as adsorbates/intermediates. Some of these bands exhibit similar (low) intensities as surface species and are in the range of typical adsorbed CO or methoxy/methanol vibrations. Higher pressures and temperatures, which are necessary to study industrial catalysts by in situ IR spectroscopy, even amplify this effect. In addition, due to a Fermi resonance at a CO2 partial pressure above ∼10 bar, two further bands appear at 1388 and 1285 cm−1. This is also within the range typically associated with surface adsorbates. In order to avoid misassignments of IR bands for in situ or operando DRIFT spectroscopy, those occurring at CO2 pressures up to 30 bar in the widely used Praying Mantis TM High Temperature Reaction Chamber are presented here and assigned to their origin as combination bands and overtones of gaseous CO2
Download or read book Experimental Study of the Oscillatory Behavior of CO Oxidation on Pt Al2O3 by in Situ Infrared Transmission Spectroscopy written by Abdulhafied E. Elhaderi and published by . This book was released on 1982 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fossil Energy Update written by and published by . This book was released on 1981 with total page 826 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CO Oxidation Catalysis with Substituted Ceria Nanoparticles written by Joseph Spanjaard Elias and published by . This book was released on 2016 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: The low-temperature and cost-effective oxidation of carbon monoxide to carbon dioxide remains a fundamental challenge in heterogeneous catalysis that would enable a diverse range of technologies for electrochemical storage and respiratory health. The development of new catalysts is often driven by high-throughput screening and many of the resulting compounds are mixed-phase, which obscures a rigorous identification of active sites and mechanisms at play for catalysis. In this thesis, the preparation of substituted ceria nanoparticles is described to bring about a fundamental understanding of the structure of the active sites, mechanism and design descriptors for CO oxidation on ceria-based catalysts. Monodisperse, single-phase nanoparticles of late first-row transition-metal-substituted ceria (MyCe1.yO2-x, M = Mn, Fe, Co, Ni and Cu) are prepared from the controlled pyrolysis of heterobimetallic precursors in amine surfactant solutions. By means of kinetic analyses, X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM), the active site for CO oxidation catalysis is identified as atomically-dispersed, square-planar M3+ and M2+ moieties substituted into the surface of the ceria lattice. The introduction of CuO does not contribute to the catalytic activity of CuyCe1.yO2-x, lending support to the hypothesis that the substituted ceria itself is responsible for the catalytic rate enhancement in mixed-phased catalysts like CuO/CeO2 Under oxygen-rich conditions, the kinetic parameters for CO oxidation are consistent with lattice oxygen from the dispersed copper sites contributing directly to the oxidation of CO in the rate-determining step. In-situ X-ray photoelectron spectroscopy (XPS) and FTIR studies indicate that adsorbed CO can be directly oxidized to CO2 in the absence of gaseous O2, while in-situ XAS confirms that electron transfer is localized to the copper sites. XAS studies demonstrate that the reversible reducibility of dispersed copper ions is a contributing factor for the special catalytic activity of CuO/CeO2 catalysts. The oxygen-ion vacancy formation energy is introduced as an activity descriptor to rationalize trends in the catalytic activities measured for MyCe1-yO2-x nanoparticles that span over three orders of magnitude. As such, the DFT-calculated vacancy formation energy serves to guide in the rational design of catalysts through computational, rather than experimental, screening of candidate compounds for CO oxidation catalysis.
Download or read book Spectroscopic studies on heterogeneous oxidation catalysts written by Bo Jonson and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mesoporous Zeolites written by Javier García-Martínez and published by John Wiley & Sons. This book was released on 2015-05-26 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: Authored by a top-level team of both academic and industrial researchers in the field, this is an up-to-date review of mesoporous zeolites. The leading experts cover novel preparation methods that allow for a purpose-oriented fine-tuning of zeolite properties, as well as the related materials, discussing the specific characterization methods and the applications in close relation to each individual preparation approach. The result is a self-contained treatment of the different classes of mesoporous zeolites. With its academic insights and practical relevance this is a comprehensive handbook for researchers in the field and related areas, as well as for developers from the chemical industry.
Download or read book Rhodium Catalyzed Hydroformylation written by Piet W.N.M. van Leeuwen and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade there have been numerous advances in the area of rhodium-catalyzed hydroformylation, such as highly selective catalysts of industrial importance, new insights into mechanisms of the reaction, very selective asymmetric catalysts, in situ characterization and application to organic synthesis. The views on hydroformylation which still prevail in the current textbooks have become obsolete in several respects. Therefore, it was felt timely to collect these advances in a book. The book contains a series of chapters discussing several rhodium systems arranged according to ligand type, including asymmetric ligands, a chapter on applications in organic chemistry, a chapter on modern processes and separations, and a chapter on catalyst preparation and laboratory techniques. This book concentrates on highlights, rather than a concise review mentioning all articles in just one line. The book aims at an audience of advanced students, experts in the field, and scientists from related fields. The didactic approach also makes it useful as a guide for an advanced course.
Download or read book Atomically Precise Metal Nanoclusters written by Zhikun Wu and published by Morgan & Claypool Publishers. This book was released on 2020-11-06 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atomically precise metal nanocluster research has emerged as a new frontier. This book serves as an introduction to metal nanoclusters protected by ligands. The authors have summarized the synthesis principles and methods, the characterization methods and new physicochemical properties, and some potential applications. By pursuing atomic precision, such nanocluster materials provide unprecedented opportunities for establishing precise relationships between the atomic-level structures and the properties. The book should be accessible to senior undergraduate and graduate students, researchers in various fields (e.g., chemistry, physics, materials, biomedicine, and engineering), R&D scientists, and science policy makers.
Download or read book Fuel Cell Catalysis written by Andrzej Wieckowski and published by John Wiley & Sons. This book was released on 2009-04-01 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wiley Series on Electrocatalysis and Electrochemistry Fuel Cell Catalysis A Surface Science Approach A Core reference on fuel cell catalysis Fuel cells represent an important alternative energy source and a very active area of research. Fuel Cell Catalysis brings together world leaders in this field, providing a unique combination of state-of-the-art theory and computational and experimental methods. With an emphasis on understanding fuel cell catalysis at the molecular level, this text covers fundamental principles, future challenges, and important current research themes. Fuel Cell Catalysis: Provides a molecular-level description of catalysis for low-temperature polymer-electrolyte membrane fuel cells, including both hydrogen-oxygen cells and direct alcohol cells Examines catalysis issues of both anode and cathode such as oxygen reduction, alcohol oxidation, and CO tolerance Features a timely and forward-looking approach through emphasis on novel aspects such as computation and bio-inspiration Reviews the use and potential of surface-sensitive techniques like vibrational spectroscopy (IR, Raman, nonlinear spectroscopy, laser), scanning tunneling microscopy, X-ray scattering, NMR, electrochemical techniques, and more Reviews the use and potential of such modern computational techniques as DFT, ab initio MD, kinetic Monte Carlo simulations, and more Surveys important trends in reactivity and structure sensitivity, nanoparticles, "dynamic" catalysis, electrocatalysis vs. gas-phase catalysis, new experimental techniques, and nontraditional catalysts This cutting-edge collection offers a core reference for electrochemists, electrocatalysis researchers, surface and physical chemists, chemical and automotive engineers, and researchers in academia, research institutes, and industry.
Download or read book Third World Congress on Oxidation Catalysis written by S.T. Oyama and published by Elsevier. This book was released on 1997-09-12 with total page 1277 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall theme of the 3rd World Congress is "Atom Efficient Catalytic Oxidations for Global Technologies". This theme was chosen to stimulate the participants to report their findings with an emphasis on conserving valuable material in their catalytic transformations, as well as conserving energy, in an environmentally responsible manner. Progress towards this stated goal is substantial as evidenced by the tremendous response of the community in their participation of quality publications complied in these Proceedings of the Congress.The subjects presented span a wide range of oxidation reactions and catalysts. These include the currently important area of lower alkane oxidation to the corresponding olefins, unsaturated aldehydes, acids and nitriles.The four featured lectures and seven plenary lectures constitute the general background and overview of the subject matter at hand. The 104 contributed papers and 13 poster manuscripts, summarized in this compendium, probe new avenues to achieve catalytically efficient oxidation reactions for the future needs of mankind in a global environment.
