Synthesis, Characterization and Catalytic Activity of Highly Dispersed Metal and Metal Oxide-supported Metal Particals Derived from Organometallic Precursors PDF Download
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Author: Zhibang Duan
Publisher:
ISBN:
Category : Metallic oxides
Languages : en
Pages : 514
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Author: Zhibang Duan
Publisher:
ISBN:
Category : Metallic oxides
Languages : en
Pages : 514
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Author: Bert Donald Chandler
Publisher:
ISBN:
Category :
Languages : en
Pages : 576
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Author: Marcela Martinez Tejada
Publisher: MDPI
ISBN: 3039287222
Category : Technology & Engineering
Languages : en
Pages : 204
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Book Description
The future of the precious metals is shiny and resistant. Although expensive and potentially replaceable by transition metal catalysts, precious metal implementation in research and industry shows potential. These metals catalyze oxidation and hydrogenation due to their dissociative behavior toward hydrogen and oxygen, dehydrogenation, isomerization, and aromatization, etc. The precious metal catalysts, especially platinum-based catalysts, are involved in a variety of industrial processes. Examples include Pt–Rh gauze for nitric acid production, the Pt/Al2O3 catalyst for cyclohexane and propylene production, and Pd/Al2O3 catalysts for petrochemical hydropurification reactions, etc. A quick search of the number of published articles in the last five years containing a combination of corresponding “metals” (Pt, Pd, Ru, Rh and Au) and “catalysts” as keywords indicates the importance of the Pt catalysts, but also the continuous increase in the contribution of Pd and Au. This Special Issue reveals the importance of precious metals in catalysis and focuses on mono- and bi-metallic formulations of any supported precious metals and their promotional catalytic effect of other transition metals. The application of precious metals in diverse reactions, either homogeneous or heterogeneous, and studies of the preparation, characterization, and applications of the supported precious metal catalysts, are presented.
Author: Felix ShangChung Lai
Publisher:
ISBN:
Category :
Languages : en
Pages : 1092
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Author: Robert Rioux
Publisher: Springer Science & Business Media
ISBN: 0387980490
Category : Science
Languages : en
Pages : 531
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Book Description
This book is an excellent compilation of cutting-edge research in heterogeneous catalysis and related disciplines – surface science, organometallic catalysis, and enzymatic catalysis. In 23 chapters by noted experts, the volume demonstrates varied approaches using model systems and their successes in understanding aspects of heterogeneous catalysis, both metal- and metal oxide-based catalysis in extended single crystal and nanostructured catalytic materials. To truly appreciate the astounding advances of modern heterogeneous catalysis, let us first consider the subject from a historical perspective. Heterogeneous catalysis had its beginnings in England and France with the work of scientists such as Humphrey Davy (1778–1829), Michael Faraday (1791–1867), and Paul Sabatier (1854–1941). Sabatier postulated that surface compounds, si- lar to those familiar in bulk to chemists, were the intermediate species leading to catalytic products. Sabatier proposed, for example, that NiH moieties on a Ni sur- 2 face were able to hydrogenate ethylene, whereas NiH was not. In the USA, Irving Langmuir concluded just the opposite, namely, that chemisorbed surface species are chemically bound to surfaces and are unlike known molecules. These chemisorbed species were the active participants in catalysis. The equilibrium between gas-phase molecules and adsorbed chemisorbed species (yielding an adsorption isotherm) produced a monolayer by simple site-filling kinetics.
Author: Daniel L. Fedlheim
Publisher: CRC Press
ISBN: 9780585404394
Category : Science
Languages : en
Pages : 348
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Book Description
A state-of-the-art reference, Metal Nanoparticles offers the latest research on the synthesis, characterization, and applications of nanoparticles. Following an introduction of structural, optical, electronic, and electrochemical properties of nanoparticles, the book elaborates on nanoclusters, hyper-Raleigh scattering, nanoarrays, and several applications including single electron devices, chemical sensors, biomolecule sensors, and DNA detection. The text emphasizes how size, shape, and surface chemistry affect particle performance throughout. Topics include synthesis and formation of nanoclusters, nanosphere lithography, modeling of nanoparticle optical properties, and biomolecule sensors.
Author: Ahana Mukhopadhyay
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Widespread industrial applications and large impact of supported late transitionprecious metal catalysts on the global economy serves as the prime motivation for thededication of academic researchers towards focusing on the scalable and affordable design ofefficient catalysts. Catalyst design requires a fundamental understanding of how the differentsynthetic steps (adsorption, drying, pretreatment, etc) influence the properties of the finalcatalyst. Moreover, in current times, single-atom catalysts represent an exciting new class ofmaterials that have demonstrated high activity for chemical reactions relevant to energyproduction. Among the various stages involved in catalyst synthesis, the initial adsorptionstep between the support and the precursor is believed to be of most importance as thisinteraction influences the unit operations that follow and affects the final size distribution ofthe catalyst nanoparticles. The ability of metal oxide supports to enhance the dispersion ofthe active metal on their surface and control their morphology and sintering kinetics isfundamentally related to the nature and strength of the metalsupport interaction which isdetermined at the time of adsorption at the solid-liquid interface. Documented studies on theimportance of the adsorption step on the overall characteristics of the catalyst nanoparticleare limited in recent literature due to challenges associated with probing a buried solid-liquidinterface. In this work, we have examined the molecular level details of catalyst synthesiswith substantial emphasis on the adsorption thermodynamics occurring at the solid-liquidinterface during the initial adsorption of transition metal complexes (TMCs) on metal oxidesupports and its influence on nanoparticle size, growth and stability.Using a number of surface analytical tools, we have probed at the interface during theadsorption process to quantify metal uptake and measure the kinetics and enthalpy of binding in order to identify the effect of different precursors and their ligand chemistry on the electrostatic driving force. Isothermal Titration Calorimetry (ITC) is used to contact reducible and refractory supports like SiO2, -Al2O3 and CeO2 with pH adjusted TMC solutions of Pt, Pd, Rh, Ir and Ag at adjusted pH values, providing a strong electrostatic driving force for adsorption and measure equilibrium binding constants, stoichiometry and enthalpies of adsorption. This study is unique in context that it truly probes the interface during adsorption (in situ) of metal precursors on supports rather than as-synthesized nanoparticles. The trends in the estimated thermodynamic parameters as a function of pH for both the cationic and anionic Pt complexes on silica and alumina respectively captures the effect of ligand speciation and complex solvation at acidic and basic solution conditions. Equilibrium adsorption isotherms from bench top bulk uptake studies aid in quantifying the amount of metal adsorbed on the support surface and by varying choice and weight loading of the precursors, we are able to identify that chloride ligand speciation chemistry around main metal center and solvation strongly influenced metal uptake. Next, we compared bulk and interfacial adsorption mechanisms through ex-situ synthesis to determine how the particle size distribution and metal dispersion of the catalysts were influenced by the mode of adsorption. Thereafter, we looked at cerium oxide which is an important support for transition metal catalysts due to its high oxygen storage capacity; thus allowing it to successfully stabilize noble metals, inhibit sintering and maintain small sized nanoparticles on its surface compared to other oxide supports. The thermodynamic adsorption parameters of a comprehensive list of late transition metal complexes in Group 9-11 on shape controlled faceted cerium oxide nano-crystals demonstrated by ITC and DFT calculations showed a trend in the enthalpies of binding between support and metal precursors that correlates with the oxide formation tendency of the transition metal and the reducibility of the support. The ability of metals to form atomically dispersed metal nanoparticles on cerium oxide through formation of an M-O-Ce bond under strong oxidative conditions was examined using XPS and TEM. Several combinations of catalysts were synthesized using precursors having various ligand chemistries deposited on different facets of cerium oxide nano-crystals and surface analytical tools were used to evaluate the optimal conditions for stable, highly dispersed catalysts. From these design rules, a series of ceria supported low weight loading single atom Pd catalysts were synthesized and examined for low temperature methane combustion that is highly in demand to reduce methane slip from lean-burn natural gas vehicles. Here, we probed into the effect of the transition from nano-clusters to single atoms on the activity of the reaction. A possible mechanistic change in the Pd catalytic redox cycle is believed to enhance the catalytic turnover at low temperatures while maintaining reduced precious metal usage.
Author: H.E. Curry-Hyde
Publisher: Elsevier
ISBN: 0080887600
Category : Technology & Engineering
Languages : en
Pages : 601
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Book Description
This Symposium provided the opportunity to review progress after more than 10 years of research and development in the field of natural gas conversion. Oxidative coupling of methane as a route to higher value fuels or feedstock was a major part of the program. The advances in understanding of reaction mechanisms and catalyst structure were discussed in a Plenary paper and in many of the contributed papers.The homogeneous gas phase chemistry involved in methane oxidation is relevant not only to oxidative coupling but also to synthesis gas and methanol production via partial oxidation. This field is reviewed in a Plenary paper and contributed papers describe developments in catalysts and technology for partial oxidation to synthesis gas and to methanol. An alternative route to synthesis gas from methane currently receiving attention is carbon dioxide reforming. This technology is reviewed in a Plenary paper and recent advances are described in contributed papers. The first detailed account of the Shell SMDS Fischer-Tropsch process for production of transport fuels from natural gas recently commercialised in Malaysia is given in this book. Papers discuss structural aspects of Fischer-Tropsch catalysts, modifications of Fischer-Tropsch catalysts to produce light olefins, and the possibilities of operating a Fischer-Tropsch process off-shore. Methanol as an intermediate in natural gas conversion continues to attract attention, and methanol synthesis and conversion are discussed in contributed papers. The possibilities of finding new uses for methane are treated in a Plenary paper and arguments for using methane as a fuel rather than a feedstock are also presented. Among the new uses of methane considered are the generation of electricity in fuel cells and the use of methane as a reductant for NOx emissions.The papers will be of interest to scientists and engineers working in the field of gas conversion, transportation fuels, primary petrochemicals and catalysis.
Author: Jean-Marie Basset
Publisher: Springer Science & Business Media
ISBN: 9400929714
Category : Science
Languages : en
Pages : 340
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Book Description
Surface organometallic chemistry is a new field bringing together researchers from organometallic, inorganic, and surface chemistry and catalysis. Topics ranging from reaction mechanisms to catalyst preparation are considered from a molecular basis, according to which the "active site" on a catalyst surface has a supra-molecular character. This. the first book on the subject, is the outcome of a NATO Workshop held in Le Rouret. France, in May. 1986. It is our hope that the following chapters and the concluding summary of recommendations for research may help to provide a definition of surface organometallic chemistry. Besides catalysis. the central theme of the Workshop, four main topics are considered: 1) Reactions of organometallics with surfaces of metal oxides, metals. and zeolites; 2) Molecular models of surfaces, metal oxides, and metals; 3) Molecular approaches to the mechanisms of surface reactions; 4) Synthesis and modification of zeolites and related microporous solids. Most surface organometallic chemistry has been carried out on amorphous high-surf ace-area metal oxides such as silica. alumina. magnesia, and titania. The first chapter. contributed by KNOZINGER. gives a short summary of the structure and reactivity of metal oxide surfaces. Most of our understanding of these surfaces is based on acid base and redox chemistry; this chemistry has developed from X-ray and spectroscopic data, and much has been inferred from the structures and reactivities of adsorbed organic probe molecules. There are major opportunities for extending this understanding by use of well-defined (single crystal) oxide surfaces and organometallic probe molecules.
Author: Brent Edward Handy
Publisher:
ISBN:
Category :
Languages : en
Pages : 638
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Book Description
