Download or read book Support Effects in Catalysis Studied by In situ Sum Frequency Generation Vibrational Spectroscopy and In situ X Ray Spectroscopies written by Griffin John Kennedy and published by . This book was released on 2016 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Kinetic measurements are paired with in-situ spectroscopic characterization tools to investigate colloidally based, supported Pt catalytic model systems in order to elucidate the mechanisms by which metal and support work in tandem to dictate activity and selectivity. The results demonstrate oxide support materials, while inactive in absence of Pt nanoparticles, possess unique active sites for the selective conversion of gas phase molecules when paired with an active metal catalyst. In order to establish a paradigm for metal-support interactions using colloidally synthesized Pt nanoparticles the ability of the organic capping agent to inhibit reactivity and interaction with the support must first be assessed. Pt nanoparticles capped by poly(vinylpyrrolidone) (PVP), and those from which the PVP is removed by UV light exposure, are investigated for two reactions, the hydrogenation of ethylene and the oxidation of methanol. It is shown that prior to PVP removal the particles are moderately active for both reactions. Following removal, the activity for the two reactions diverges, the ethylene hydrogenation rate increases 10-fold, while the methanol oxidation rate decreases 3-fold. To better understand this effect the capping agent prior to, and the residual carbon remaining after UV treatment are probed by sum frequency generation vibrational spectroscopy. Prior to removal no major differences are observed when the particles are exposed to alternating H2 and O2 environments. When the PVP is removed, carbonaceous fragments remain on the surface that dynamically restructure in H2 and O2. These fragments create a tightly bound shell in an oxygen environment and a porous coating of hydrogenated carbon in the hydrogen environment. This observation explains the divergent catalytic results. Reaction rate measurements of thermally cleaned PVP and oleic acid capped particles show this effect to be independent of cleaning method or capping agent. In all this demonstrates the ability of the capping agent to mediate nanoparticle catalysis. With this established the hydrogenation of furfural by Pt supported on SiO2 and TiO2 was investigated by an approach combining reaction studies with SFG in order to gain molecular level insight into the nature of the metal-support interaction. This is the first instance of SFG being used to probe the factors governing selectivity in a supported catalyst system. This work revealed that TiO2 possessed sites that, while inactive without Pt, became highly active for the selective conversion of furfural to furfuryl alcohol. By SFG a TiO2 bound intermediate species was identified that could explain the highly selective nature of the reaction by Pt/TiO2. In combination with density functional theory calculations it was determined that furfural bound favorably to oxygen vacancy sites on the TiO2 surface through the aldehyde oxygen, which in turn activated the aldehyde group for hydrogenation by a charge transfer mechanism. This intermediate could then react with spillover hydrogen from the Pt surface to form furfuryl alcohol. In an effort to generalize this mechanism to additional molecules and reducible oxides the work was expanded to the hydrogenation of crotonaldehyde with cobalt oxide as an additional support. Reaction studies and SFG study of the Pt/TiO2, Pt/Co3O4, and Pt/SiO2 catalysts, revealed a reaction pathway for Pt/TiO2 and Pt/Co3O4 which selectively produced alcohol products, crotyl alcohol and butanol, while no alcohol production was observed for the Pt/SiO2 catalyst. A thorough study of the possible secondary reaction pathways revealed that butanol was formed in a concerted manner, rather than through sequential hydrogenation of the C=C and C=O groups. Sum frequency generation studies revealed that Pt supported on SiO2 yielded identical reaction intermediates as Pt single crystals, further cementing the passive role of SiO2. Spectra obtained from the cobalt and titanium oxide supported catalysts revealed adsorption sites exist on the oxide surfaces through which the molecule binds via the aldehyde group. These sites are believed to be the active sites for alcohol production. In the case of Co3O4 ambient pressure x-ray photoelectron spectroscopy and x-ray absorption spectroscopy reveal a reduction of the oxide surface under reaction conditions indicating the adsorption sites on the oxide exist on a reduced surface, additional evidence for the site being an O-vacancy. To better understand the interplay between the formation of the two alcohols a Pt nanoparticle density dependence study was undertaken for the Co3O4 case. It was observed that increasing the Pt density, thus increasing the ratio of interface to oxide surface sites, led to an increase in butanol and decrease in crotyl alcohol production. From this it is proposed that butanol forms at the Pt-oxide interface while the crotyl alcohol forms via the spillover mechanism at an oxide site. Lastly a before undiscovered example of encapsulation of a metal particle by an oxide support is observed for the Pt/Co3O4 system by ambient pressure x-ray photoelectron spectroscopy. Under mild conditions an encapsulated state is reached in which the oxide covers the Pt surface, yet does not inhibit reactivity. In fact the total activity of the catalyst increases dramatically and a change in product selectivity was observed. By SFG it is seen that the features of a Pt bound butyraldehyde intermediate increase in intensity, which is directly correlated to a 3-fold increase in butyraldehyde activity. This work builds on a vast knowledge of catalyst-support interactions in heterogeneous catalysis by applying in-situ techniques to yield a molecular level understanding of the surface processes.
Download or read book Preparation of Catalysts on Model Supports Using Wet Chemical Methods and the Construction of a Device for the In situ Measurement of Sum Frequency Generation Spectroscopy at the Solid liquid Interface written by and published by . This book was released on 2013 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nanotechnology in Catalysis written by Bert Sels and published by John Wiley & Sons. This book was released on 2017-06-21 with total page 1500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflecting the R&D efforts in the field that have resulted in a plethora of novel applications over the past decade, this handbook gives a comprehensive overview of the tangible benefits of nanotechnology in catalysis. By bridging fundamental research and industrial development, it provides a unique perspective on this scientifically and economically important field. While the first three parts are devoted to preparation and characterization of nanocatalysts, the final three provide in-depth insights into their applications in the fine chemicals industry, the energy industry, and for environmental protection, with expert authors reporting on real-life applications that are on the brink of commercialization. Timely reading for catalytic chemists, materials scientists, chemists in industry, and process engineers.
Download or read book Morphological Compositional and Shape Control of Materials for Catalysis written by Paolo Fornasiero and published by Elsevier. This book was released on 2017-05-23 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt: Morphological, Compositional, and Shape Control of Materials for Catalysis, Volume 177, the latest in the Studies in Surface Science and Catalysis series, documents the fast-growing developments in the synthesis, characterization, and utilization of nanostructures for catalysis. The book provides essential background on using well-defined materials for catalysis and presents exciting new paradigms in the preparation and application of catalytic materials, with an emphasis on how structure determines catalytic properties. In addition, the book uniquely features discussions on the future of the field, with ample space for future directions detailed in each chapter. - Presents the latest paradigms in the preparation and application of catalytic materials - Provides essential background on using well-defined materials for catalysis - Features discussion of future directions at the end of each chapter
Download or read book Strong Metal support Interactions written by R. T. K. Baker and published by . This book was released on 1986 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Catalytic Reaction Intermediates by Sum Frequency Generation Vibrational Spectroscopy on Single Crystal Surfaces of Metals written by Xingcai Su and published by . This book was released on 1998 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Report written by Bjerne S. Clausen and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In situ Characterization of Heterogeneous Catalysts written by José A. Rodriguez and published by John Wiley & Sons. This book was released on 2013-04-17 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: Helps researchers develop new catalysts for sustainable fueland chemical production Reviewing the latest developments in the field, this bookexplores the in-situ characterization of heterogeneous catalysts,enabling readers to take full advantage of the sophisticatedtechniques used to study heterogeneous catalysts and reactionmechanisms. In using these techniques, readers can learn to improvethe selectivity and the performance of catalysts and how to preparecatalysts as efficiently as possible, with minimum waste. In-situ Characterization of Heterogeneous Catalysts featurescontributions from leading experts in the field of catalysis. Itbegins with an introduction to the fundamentals and thencovers: Characterization of electronic and structural properties ofcatalysts using X-ray absorption fine structure spectroscopy Techniques for structural characterization based on X-raydiffraction, neutron scattering, and pair distribution functionanalysis Microscopy and morphological studies Techniques for studying the interaction of adsorbates withcatalyst surfaces, including infrared spectroscopy, Ramanspectroscopy, EPR, and moderate pressure XPS Integration of techniques that provide information on thestructural properties of catalysts with techniques that facilitatethe study of surface reactions Throughout the book, detailed examples illustrate how techniquesfor studying catalysts and reaction mechanisms can be applied tosolve a broad range of problems in heterogeneous catalysis.Detailed figures help readers better understand how and why thetechniques discussed in the book work. At the end of each chapter,an extensive set of references leads to the primary literature inthe field. By explaining step by step modern techniques for the in-situcharacterization of heterogeneous catalysts, this book enableschemical scientists and engineers to better understand catalystbehavior and design new catalysts for green, sustainable fuel andchemical production.
Download or read book X Ray Absorption and X Ray Emission Spectroscopy 2 Volume Set written by Jeroen A. van Bokhoven and published by John Wiley & Sons. This book was released on 2016-03-21 with total page 940 pages. Available in PDF, EPUB and Kindle. Book excerpt: X-Ray Absorption and X-ray Emission Spectroscopy: Theory and Applications During the last two decades, remarkable and often spectacular progress has been made in the methodological and instrumental aspects of x-ray absorption and emission spectroscopy. This progress includes considerable technological improvements in the design and production of detectors especially with the development and expansion of large-scale synchrotron reactors All this has resulted in improved analytical performance and new applications, as well as in the perspective of a dramatic enhancement in the potential of x-ray based analysis techniques for the near future. This comprehensive two-volume treatise features articles that explain the phenomena and describe examples of X-ray absorption and emission applications in several fields, including chemistry, biochemistry, catalysis, amorphous and liquid systems, synchrotron radiation, and surface phenomena. Contributors explain the underlying theory, how to set up X-ray absorption experiments, and how to analyze the details of the resulting spectra. X-Ray Absorption and X-ray Emission Spectroscopy: Theory and Applications: Combines the theory, instrumentation and applications of x-ray absorption and emission spectroscopies which offer unique diagnostics to study almost any object in the Universe. Is the go-to reference book in the subject for all researchers across multi-disciplines since intense beams from modern sources have revolutionized x-ray science in recent years Is relevant to students, postdocurates and researchers working on x-rays and related synchrotron sources and applications in materials, physics, medicine, environment/geology, and biomedical materials
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 Introduction to Surface Chemistry and Catalysis written by Gabor A. Somorjai and published by Wiley-Interscience. This book was released on 1994-03-18 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt: Among the topics covered are adhesion and tribological properties, friction, crack formation, and lubrication.
Download or read book Monitored Natural Attenuation of Inorganic Contaminants in Ground Water written by and published by . This book was released on 2007 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: V.3 ... consists of individual chapters that describe 1) the conceptual background for radionuclides, including tritium, radon, strontium, technetium, uranium, iodine, radium, thorium, cesium, plutonium-americium and 2) data requirements to be met during site characterization.
Download or read book Stimulated Raman Scattering Microscopy written by Ji-Xin Cheng and published by Elsevier. This book was released on 2021-12-04 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stimulated Raman Scattering Microscopy: Techniques and Applications describes innovations in instrumentation, data science, chemical probe development, and various applications enabled by a state-of-the-art stimulated Raman scattering (SRS) microscope. Beginning by introducing the history of SRS, this book is composed of seven parts in depth including instrumentation strategies that have pushed the physical limits of SRS microscopy, vibrational probes (which increased the SRS imaging functionality), data science methods, and recent efforts in miniaturization. This rapidly growing field needs a comprehensive resource that brings together the current knowledge on the topic, and this book does just that. Researchers who need to know the requirements for all aspects of the instrumentation as well as the requirements of different imaging applications (such as different types of biological tissue) will benefit enormously from the examples of successful demonstrations of SRS imaging in the book. Led by Editor-in-Chief Ji-Xin Cheng, a pioneer in coherent Raman scattering microscopy, the editorial team has brought together various experts on each aspect of SRS imaging from around the world to provide an authoritative guide to this increasingly important imaging technique. This book is a comprehensive reference for researchers, faculty, postdoctoral researchers, and engineers. - Includes every aspect from theoretic reviews of SRS spectroscopy to innovations in instrumentation and current applications of SRS microscopy - Provides copious visual elements that illustrate key information, such as SRS images of various biological samples and instrument diagrams and schematics - Edited by leading experts of SRS microscopy, with each chapter written by experts in their given topics
Download or read book Nanotechnology in Catalysis 3 written by Bing Zhou and published by Springer Science & Business Media. This book was released on 2007-09-05 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume continues the tradition formed in Nanotechnology in Catalysis 1 and 2. As with those books, this one is based upon an ACS symposium. Some of the most illustrious names in heterogeneous catalysis are among the contributors. The book covers: Design, synthesis, and control of catalysts at nanoscale; understanding of catalytic reaction at nanometer scale; characterization of nanomaterials as catalysts; nanoparticle metal or metal oxides catalysts; nanomaterials as catalyst supports; new catalytic applications of nanomaterials.
Download or read book Fundamental Concepts in Heterogeneous Catalysis written by Jens K. Nørskov and published by John Wiley & Sons. This book was released on 2014-10-27 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is based on a graduate course and suitable as a primer for any newcomer to the field, this book is a detailed introduction to the experimental and computational methods that are used to study how solid surfaces act as catalysts. Features include: First comprehensive description of modern theory of heterogeneous catalysis Basis for understanding and designing experiments in the field Allows reader to understand catalyst design principles Introduction to important elements of energy transformation technology Test driven at Stanford University over several semesters
Download or read book Transmission Electron Microscopy written by C. Barry Carter and published by Springer. This book was released on 2016-08-24 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text is a companion volume to Transmission Electron Microscopy: A Textbook for Materials Science by Williams and Carter. The aim is to extend the discussion of certain topics that are either rapidly changing at this time or that would benefit from more detailed discussion than space allowed in the primary text. World-renowned researchers have contributed chapters in their area of expertise, and the editors have carefully prepared these chapters to provide a uniform tone and treatment for this exciting material. The book features an unparalleled collection of color figures showcasing the quality and variety of chemical data that can be obtained from today’s instruments, as well as key pitfalls to avoid. As with the previous TEM text, each chapter contains two sets of questions, one for self assessment and a second more suitable for homework assignments. Throughout the book, the style follows that of Williams & Carter even when the subject matter becomes challenging—the aim is always to make the topic understandable by first-year graduate students and others who are working in the field of Materials Science Topics covered include sources, in-situ experiments, electron diffraction, Digital Micrograph, waves and holography, focal-series reconstruction and direct methods, STEM and tomography, energy-filtered TEM (EFTEM) imaging, and spectrum imaging. The range and depth of material makes this companion volume essential reading for the budding microscopist and a key reference for practicing researchers using these and related techniques.
Download or read book Chemisorption and Reactivity on Supported Clusters and Thin Films written by R.M. Lambert and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt: Heterogeneous catalysis provides the backbone of the world's chemical and oil industries. The innate complexity of practical catalytic systems suggests that useful progress should be achievable by investigating key aspects of catalysis by experimental studies on idealised model systems. Thin films and supported clusters are two promising types of model system that can be used for this purpose, since they mimic important aspects of the properties of practical dispersed catalysts. Similarly, appropriate theoretical studies of chemisorption and surface reaction clusters or extended slab systems can provide valuable information on the factors that underlie bonding and catalytic activity. This volume describes such experimental and theoretical approaches to the surface chemistry and catalytic behaviour of metals, metal oxides and metal/metal oxide systems. An introduction to the principles and main themes of heterogeneous catalysis is followed by detailed accounts of the application of modern experimental and theoretical techniques to fundamental problems. The application of advanced experimental methods is complemented by a full description of theoretical procedures, including Hartree-Fock, density functional and similar techniques. The relative merits of the various approaches are considered and directions for future progress are indicated.
