Download or read book Physical and Chemical Characterization of Supported Platinum Catalysts and Gas Phase Silver Clusters written by Nagib George Alameddin and published by . This book was released on 1992 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical and Chemical Characterization of Iron titania Model Supported Catalysts written by Bruce John Tatarchuk and published by . This book was released on 1981 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ACS Directory of Graduate Research 1993 written by American Chemical Society. Committee on Professional Training and published by . This book was released on 1993 with total page 1700 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization and Reaction Studies of Silica Supported Platinum and Rhodium Model Catalysts written by Matthew James Lundwall and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The physical and catalytic properties of silica supported platinum or rhodium model catalysts are studied under both ultra high vacuum (UHV) and elevated pressure reaction conditions (>1torr). Platinum or rhodium nanoparticles are vapor deposited onto a SiO2/Mo(112) surface and characterized using various surface analytical methods. CO chemisorption is utilized as a surface probe to estimate the concentration of various sites on the nanoparticles through thermal desorption spectroscopy (TDS) and infrared reflection absorption spectroscopy (IRAS) along with microscopy techniques to estimate particle size. The results are compared with hard sphere models of face centered cubic metals described as truncated cubo-octahedron. Results demonstrate the excellent agreement between chemisorption and hard sphere models in estimating the concentration of undercoordinated atoms on the nanoparticle surface. Surfaces are then subjected to high pressure reaction conditions to test the efficacy of utilizing the rate of a chemical reaction to obtain structural information about the surface. The surfaces are translated in-situ to a high pressure reaction cell where both structure insensitive and sensitive reactions are performed. Structure insensitive reactions (e.g. CO oxidation) allow a method to calculate the total active area on a per atom basis for silica supported platinum and rhodium model catalysts under reaction conditions. While structure sensitive reactions allow an estimate of the types of reaction sites, such as step sites ([less than or equal to]C7) under reaction conditions (e.g. n-heptane dehydrocyclization). High pressure structure sensitive reactions (e.g. ethylene hydroformylation) are also shown to drastically alter the morphology of the surface by dispersing nanoparticles leading to inhibition of catalytic pathways. Moreover, the relationships between high index single crystals, oxide supported nanoparticles, and high surface area technical catalysts are established. Overall, the results demonstrate the utility of model catalysts in understanding the structure-activity relationships in heterogeneous catalytic reactions and the usefulness of high pressure reactions as an analytical probe of surface morphology.

Download or read book Morphological and Chemical Characterization of Catalysts Produced Via the Thermal Decomposition of Iron Pentacarbonyl written by Jonathan Phillips and published by . This book was released on 1981 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 2000 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Gaseous Platinum Clusters written by Konrad Koszinowski and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cationic platinum clusters are proposed as models for heterogeneous catalysts. In the gas phase, the intrinsic reactivities of the cluster ions can be thoroughly investigated by means of Fourier-transform ion-cyclotron-resonance mass spectrometry. The reactions probed in these experiments indeed closely resemble various industrially important processes and contribute to a better understanding of the metal's catalytic activity.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical and Chemical Characterization of Catalyst Model Systems written by Mallanagouda Dyamanagouda Patil and published by . This book was released on 1981 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Properties of Platinum Catalysts Supported on Carbon Blacks written by and published by . This book was released on 1996 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical and gas-plasma treatments were used to modify chemical/physical properties of carbon black powder commonly used to support platinum catalysts. Altered catalyst-carbon interactions affect catalyst-particle size, which can, in turn, affect catalyst activity and subsequent catalyst life. We have demonstrated that particle size of deposited platinum on carbon can be changed by carbon black pretreatments These modifications can be easily applied to carbon blacks used in fuel cells, high powered batteries, and a variety of chemical reactions where noble metal catalysts are supported on high surface area carbon blacks.

Download or read book Reactivity and Characterization of Supported Noble Metal Catalysts written by Keishla R. Rivera-Dones and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytically driven processes account for over ninety percent of industrial chemical manufacturing today. Developments in manufacturing processes are largely driven by continued improvements in catalytic materials, which aim to increase production volumes while minimizing costs along with safety and environmental hazards. In order to achieve these goals, however, a rational approach in catalyst design must be pursued that aims to understand and build upon the fundamental structural, electronic, and chemical properties governing catalytic performance. To that purpose, the work presented in this dissertation makes use of kinetic experiments, theoretical models, and advanced characterization techniques to generate a fundamental understanding of noble metal surfaces employed in a variety of catalytic reaction systems. In Chapter 2, we discuss the use of N2 physisorption, CO chemisorption, and NH3 temperature programed desorption to evaluate the effect of support acidity on the reactivity profiles of various zeolite-supported Pt and Pt-Sn catalysts for the non-oxidative coupling of methane to ethylene and aromatics. Reactivity studies for Pt-Sn/H-ZSM-5 catalysts at 973 K showed that, while all catalysts produced ethylene as the primary product, increasing support acidity led to an increase in naphthalene selectivity at the expense of benzene selectivity. Volcano-shaped profiles observed for the generation of aromatic products suggest that the formation of a reactive hydrocarbon pool on acidic support surfaces could be responsible for the oligomerization of ethylene. Notably, the Pt-Sn/H-ZSM-5 (SiO2:Al2O3 = 50) catalyst was found to be comparable to the state-of-the-art Mo/H-ZSM-5 catalysts in terms of carbon product generation and resistance to coke formation. In Chapter 3, x-ray absorption spectroscopy (XAS) was used to highlight the effect of local electronic and structural environments in specially synthesized metallic catalysts. The local coordination and nearest-neighbor distance of Pd species were evaluated to understand metal dispersion and the effect of catalyst support on the extent of bimetallic particle formation in Pd, AgPd, CuPd, and AuPd catalysts synthesized by controlled surface reactions (CSR) for a variety of amination, hydrodechlorination, and hydrogenation reactions. Near-edge structure analyses were also used on these Pd catalysts, as well as on a set of Mo-containing multi-metallic catalysts prepared by atomic layer deposition (ALD) for synthesis gas conversion, to understand catalyst reducibility along with potential support and hydrogen spillover effects on the extent of metal reduction. Chapter 4 evaluates the effects of catalyst support and pretreatment conditions on the hydrogenation of acetone over SiO2-, Al2O3-, and ZSM-5-supported platinum catalysts. Pt/ZSM-5 catalysts were found to have specific conversion rates and turnover frequencies that were 2 - 3 orders of magnitude higher than those observed over Pt/SiO2 and Pt/Al2O3 catalysts, regardless of zeolite acidity or pretreatment conditions. For Pt/ZSM-5 catalysts, the higher activity was achieved by increasing calcination and decreasing reduction temperatures, likely due to the effects of these treatments on the morphology of the platinum particles. CO-FTIR measurements showed a shift to higher frequencies of the Pt-CO band in Pt/ZSM-5 catalysts compared to Pt/SiO2, which alluded to the interactions between Pt and the porous zeolite structure as a source of the activity enhancements observed. Chapter 5 introduces the use of transient kinetics studies and theoretical modeling to explore the importance of surface coverage effects in the hydrogenation of acetone over platinum. Transient models based on steady-state microkinetics using static and dynamic inclusion of surface coverage via the Langmuir and Bragg-Williams approximations, respectively, predicted notable differences in the decay profiles of the most abundant reactive intermediate (MARI) from the catalytic surface. Experimental studies using steady-state isotopic transient kinetic analysis (SSITKA) methods served to validate the theoretical predictions for transients induced by complete acetone removal from or its substitution in the reactant feed and provided tangible evidence for the importance of surface coverage effects in understanding the reactivity of platinum catalysts for acetone hydrogenation. Lastly, Chapter 6 addresses possible future research directions in the field of transient kinetics studies.

Download or read book Surface Analysis of Zinc Oxide Silica supported Silver and Platinum Model Catalysts Under Various Conditions written by Sana Rani and published by . This book was released on 2020 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: There have been tremendous efforts in last one decade to investigate molecular level interfacial chemistry of heterogenous processes under realistic conditions. Several model catalysts have been studied with the help of state-of-the-art in-situ spectroscopic and imaging capabilities offered by modern surface science. In this dissertation the synthesis and quantitative analysis of heterogeneous systems will be explored by a variety of surface science techniques to elucidate complex electronic and chemical properties of these surfaces under ambient condition.

Download or read book Metal Nanocrystals written by Kallum M. Koczkur and published by American Chemical Society. This book was released on 2020-07-31 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our society depends heavily on metals. They are ubiquitous construction materials, critical interconnects in integrated circuits, common coinage materials, and more. Excitingly, new uses for metals are emerging with the advent of nanoscience, as metal crystals with nanoscale dimensions can display new and tunable properties. The optical and photothermal properties of metal nanocrystals have led to cancer diagnosis and treatment platforms now in clinical trials, while, at the same time, the ability to tune the surface features of metal nanocrystals is giving rise to designer catalysts that enable more sustainable use of precious resources. These are just two examples of how metal nanocrystals are addressing important social needs.

Download or read book Hydrogenation with Low Cost Transition Metals written by Jacinto Sa and published by CRC Press. This book was released on 2018-10-08 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogenation with Low-Cost Transition Metals describes recent developments in the preparation of catalysts and their catalytic abilities in chemoselective hydrogenation for the production of fine chemicals and pharmaceutical compounds. Emphasizing the use of low-cost metals (Cu, Ni, Fe, and Ag) that are often present in the form of nanoparticles, the book provides valuable reaction mechanism schemes, engineering solutions, and perspective for the field.

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.

Download or read book Porous Carbons written by Feiyu Kang and published by Elsevier. This book was released on 2021-11-04 with total page 874 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carbon materials form pores ranging in size and morphology, from micropores of less than 1nm, to macropores of more than 50nm, and from channel-like spaces with homogenous diameters in carbon nanotubes, to round spaces in various fullerene cages, including irregularly-shaped pores in polycrystalline carbon materials. The large quantity and rapid rate of absorption of various molecules made possible by these attributes of carbon materials are now used in the storage of foreign atoms and ions for energy storage, conversion and adsorption, and for environmental remediation. Porous Carbons: Syntheses and Applications focuses on the fabrication and application of porous carbons. It considers fabrication at three scales: micropores, mesopores, and macropores. Carbon foams, sponges, and 3D-structured carbons are detailed. The title presents applications in four key areas: energy storage, energy conversion, energy adsorption, including batteries, supercapacitors, and fuel cells and environmental remediation, emphasizing the importance of pore structures at the three scales, and the diffusion and storage of various ions and molecules. The book presents a short history of each technique and material, and assesses advantages and disadvantages. This focused book provides researchers with a comprehensive understanding of both pioneering and current synthesis techniques for porous carbons, and their modern applications. Presents modern porous carbon synthesis techniques and modern applications of porous carbons Presents current research on porous carbons in energy storage, conversion and adsorption, and in environmental remediation Provides a history and assessment of both pioneering and current cutting-edge synthesis techniques and materials Covers a significant range of precursor materials, preparation techniques, and characteristics Considers the future development of porous carbons and their various potential applications