Download or read book Bimetallic Catalysts written by John H. Sinfelt and published by Wiley-Interscience. This book was released on 1983-09-29 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents an account of the research on bimetallic catalysts. Focuses attention on the possibility of influencing the selectivity of chemical transformations on metal surfaces and preparing metal alloys in a highly dispersed state. Covers the validation and elucidation of the bimetallic cluster concept. Includes figures and tables.
Download or read book An Investigation of Supported Platinum and Bimetalic Oxidation Catalysts written by Michael Tiernan and published by . This book was released on 1996 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preparation of Catalysts VII written by R. Maggi and published by Elsevier. This book was released on 1998-08-17 with total page 1007 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proceedings of the VIIth International Symposium on the Scientific Bases for the Preparation of Heterogeneous Catalysts, are in line with the general scope of this series of events. Emphasis in all Symposia has been on the scientific aspects of the preparation of new and industrial catalysts, or on new methods of preparation, rather than on the catalytic reactions in which such solids are ultimately used. In the present context, the catalytic event itself has only been considered as another, though often decisive, method of catalyst characterization.
Download or read book Construction and Reactivity of Pt Based Bi component Catalytic Systems written by Rentao Mu and published by Springer. This book was released on 2017-06-20 with total page 99 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, the author outlines the construction of active structure and modulation of catalytic reactivity of Pt-based bi-component catalysts, from the model systems to real supported catalysts. The thesis investigates the promotion effect of the second components on catalytic performance of Pt catalysts, and presents the reversible generation of the “sandwich-like” structure of Pt-Ni catalysts, containing both surface NiO1-X and subsurface Ni by alternating redox treatments at medium temperature. With the aid of single layer graphene, the dynamic process of chemical reactions occurring on the Pt(111) surface can be visualized using in-situ LEEM and DUV-PEEM techniques, the results of which are included here. The author reveals that the graphene layer exhibits a strong confinement effect on the chemistry of molecules underneath and the intercalated CO can desorb from the Pt surface around room temperature and in UHV, which may promote the CO oxidation confined under graphene.
Download or read book Supported Mono and Bimetallic Complexes and Clusters written by Joseph David Kistler and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Site-isolated solid supported metal catalysts are important in industry and technology due to the cost efficiency to make and to recover and reuse them. These types of materials have catalytic properties similar to molecular complexes in solution while being easy to separate in heterogeneous catalytic reactions. The goal of this work was to synthesize supported metal complex catalysts while maintaining uniform catalytic sites. The syntheses were performed using precise glovebox and Schlenk techniques to achieve these highly uniform structures. These materials were then used to understand the relationship between structure of a catalytic site and the activity of the catalyst. This fundamental understanding of catalysts is important in advancing the field of catalysis. The structure of the catalysts were characterized using infrared (IR), extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopies along with high angle annular dark field- scanning transmission electron microscopy (HAADF-STEM), with the HAADF-STEM work carried out by colleagues in other research groups. The catalytic activity of the catalysts was examined with gas chromatography (GC) and mass spectrometry (MS). The samples characterized in this work include complexes and clusters of second and third row transition metals supported on highly crystalline metal oxides. Specifically, there is a large focus in this work on supported rhodium complexes prepared from the organometallic precursor, Rh(C2H4)2(C5H7O2) and a pre-calcined magnesium oxide (MgO). This specific catalyst is important as not only is it active for olefin hydrogenation at mild temperatures but also there are reports of a unique surface mediated synthesis of uniform rhodium dimers, which are ideal for catalytic comparison of structures with different nuclearities. Reactivities of the MgO-supported rhodium complexes and dimers for carbon monoxide oxidation were investigated with the results showing the dimers were significantly more active for the reaction at 353 K. The stability of the dimers was tested in different reactive conditions with the results showing that under conditions with excess oxygen, the dimers are less stable and less active than under conditions with excess carbon monoxide.A bimetallic catalyst was synthesized on MgO incorporating rhodium and osmium using Rh(C2H4)2 (acac) and Os3(CO)12 as precursors. A unique synthesis method was developed to create a site-isolated segregated bimetallic catalyst with the osmium and rhodium sites acting independently of each other for ethylene hydrogenation at 298 K. The metals remained structurally segregated and catalytically independent even following reduction in H2 at 393 K. Zeolites, another class of highly crystalline supports, were studied to gain information on the support effects in catalysts. The analogous rhodium complexes as were synthesized on the MgO were synthesized on zeolite HY. These catalysts were tested to determine structural and catalytic stability under hydrogen, a reducing gas, and CO, a catalyst poison, with the results showing that, as compared to the complexes on zeolite HY, MgO-supported rhodium complexes form more uniform stable clusters under H2 and develop unique catalytic properties, selectivity for partial hydrogenation of dienes, when exposed to CO. Another zeolite, KLTL, was studied with supported platinum complexes synthesized from the salt precursor, Pt(NH3)4(NO3)2. This catalyst was oxidized at 633K to form supported single-atom platinum complexes. Both the as-prepared Pt(NH3)4 and oxidized PtOx complexes were analyzed structurally and studied as catalysts for CO oxidation. The oxidized platinum complexes proved to have significantly higher activity for CO oxidation at 423 K. Furthermore, HAADF-STEM was used to directly identify the locations of the platinum atoms in the pores of the zeolite before and after oxidative treatment, providing a method of ex-situ tracking of supported metal atoms.
Download or read book Spillover and Mobility of Species on Solid Surfaces written by A. Guerrero-Ruiz and published by Elsevier. This book was released on 2001-08-02 with total page 501 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Spillover and Mobility of Species and Solid Surfaces" collects the papers which were presented at the Fifth International Conference Spillover, either as oral or poster contributions, as well as the summaries of the invited lectures. This congress and its publication in the Studies on Surface Science and Catalysis series follow the tradition of previous conferences on spillover, initiated in Lyon, 1983, and continued in Leipzig, 1989, Kyoto 1993 and Dalian, 1997. For the fifth conference, held in S.L. el Escorial (Madrid), the organising committee has attempted to compile representative contributions which illustrate the advances in understanding the spillover phenomenon since 1997. Spillover is a process taking place during the interface of gas reactant molecules (mainly hydrogen and oxygen) on solid surfaces. However, different contributions to the more general area of the chemistry at surfaces, related with the mobility and migration of species, diffusion through membranes, fuel cell catalysts, etc., have also been included. In fact the title of the present volume summarizes this attempt to extend the conference topics towards dynamics at surfaces.Among the 70 contributions received, the 56 accepted papers were selected on the basis of the reports of at least two international reviewers, according to standards comparable to those applied for other specialised journals. These papers are from 21 different countries.
Download or read book Catalyst Preparation written by John Regalbuto and published by CRC Press. This book was released on 2016-04-19 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text explores the optimization of catalytic materials through traditional and novel methods of catalyst preparation, characterization, and monitoring for oxides, supported metals, zeolites, and heteropolyacids. It focuses on the synthesis of bulk materials and of heterogeneous materials, particularly at the nanoscale. The final chapters examine pretreatment, drying, finishing effects, and future applications involving catalyst preparation and the technological advances necessary for continued progress. Topics also include heat and mass transfer limitations, computation methods for predicting properties, and catalyst monitoring on laboratory and industrial scales.
Download or read book Supported Metals in Catalysis written by James Arthur Anderson and published by World Scientific. This book was released on 2012 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions from experts in supported metal catalysis from both the industry and academia, this book presents the latest developments in characterization and application of supported metals in heterogeneous catalysis. In addition to thorough and updated coverage of the traditional aspects of heterogeneous catalysis such as preparation, characterization and use in well-established technologies such as vehicle emission control, the book also includes emerging areas where supported metal catalysis will make significant contributions to future developments, such as fuel cells and fine chemicals synthesis. The second edition of Supported Metals in Catalysis comes complete with new and updated chapters containing important summaries of research in a rapidly evolving field. Very few other books deal with this highly pertinent subject matter and, as such, it is a must-have for anyone working in the field of heterogeneous catalysis.
Download or read book Supported Bimetallic Catalysts Derived from Platinum gold Phosphine Stabilized Cluster Compounds Their Preparation Characterization and Catalytic Activity written by Irina Vladimirovna Gubkina Graf and published by . This book was released on 1996 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific Bases for the Preparation of Heterogeneous Catalysts written by E. Gaigneaux and published by Elsevier. This book was released on 2002-08-29 with total page 1150 pages. Available in PDF, EPUB and Kindle. Book excerpt: It has become a tradition that every four years, the Université Catholique de Louvain and the Katholieke Universiteit Leuven jointly organize a symposium devoted to the scientific bases for the preparation of heterogeneous catalysts. These meetings bring together researchers from academia and industry and offer a forum for discussions on the chemistry involved in the preparation of industrial heterogeneous catalysts. This volume containing the Proceedings of the 8th International Symposium on Scientific Bases for the Preparation of Heterogeneous Catalysts consists of papers summarizing most of the 139 oral communications and posters selected by the international scientific committee, composed of 27 experts in the field of catalyst preparation, holding an industrial or academia appointment. The contributions focus on the aspects of catalyst preparation. The main topics are: new approaches in catalyst preparation; advanced preparations of nanoporous and mesoporous catalysts; catalysts preparation for special performances and purposes; catalysts for environmental purposes; and molecular catalysis. Emphasis is put on the role that catalysis can play as an essential element of sustainable development.
Download or read book Nanoalloys written by Florent Calvo and published by Newnes. This book was released on 2013-03-12 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoalloys: From Fundamentals to Emergent Applications presents and discusses the major topics related to nanoalloys at a time when the literature on the subject remains scarce. Particular attention is paid to experimental and theoretical aspects under the form of broad reviews covering the most recent developments. The book is organized into 11 chapters covering the most fundamental aspects of nanoalloys related to their synthesis and characterization, as well as their theoretical study. Aspects related to their thermodynamics and kinetics are covered as well. The coverage then moves to more specific topics, including optics, magnetism and catalysis, and finally to biomedical applications and the technologically relevant issue of self-assembly. With no current single reference source on the subject, the work is invaluable for researchers as the nanoscience field moves swiftly to full monetization. Encapsulates physical science of structure, properties, size, composition and ordering at nanoscale, aiding synthesis of experimentation and modelling Multi-expert and interdisciplinary perspectives on growth, synthesis and characterization of bimetallic clusters and particulates supports expansion of your current research activity into applications Synthesizes concepts and draws links between fundamental metallurgy and cutting edge nanoscience, aiding interdisciplinary research activity
Download or read book Structure property Relationship of Supported Platinum 3d Bimetallic Catalysts written by William W. Lonergan and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation of Gauze Supported Platinum Alumina and Cobalt Supported Oxide Oxidation Catalysts written by Michael James Ronane and published by . This book was released on 2005 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Studies of the Reforming of Oxygenated Compounds Over Supported Metal Catalysts written by and published by . This book was released on 2016 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: The main objective of our research has been to elucidate fundamental concepts associated with controlling the activity, selectivity, and stability of bifunctional, metal-based heterogeneous catalysts for tandem reactions, such as liquid-phase conversion of oxygenated hydrocarbons derived from biomass. We have shown that bimetallic catalysts that combine a highly-reducible metal (e.g., platinum) with an oxygen-containing metal promoter (e.g., molybdenum) are promising materials for conversion of oxygenated hydrocarbons because of their high activity for selective cleavage for carbon-oxygen bonds. We have developed methods to stabilize metal nanoparticles against leaching and sintering under liquid-phase reaction conditions by using atomic layer deposition (ALD) to apply oxide overcoat layers. We have used controlled surface reactions to produce bimetallic catalysts with controlled particle size and controlled composition, with an important application being the selective conversion of biomass-derived molecules. The synthesis of catalysts by traditional methods may produce a wide distribution of metal particle sizes and compositions; and thus, results from spectroscopic and reactions kinetics measurements have contributions from a distribution of active sites, making it difficult to assess how the size and composition of the metal particles affect the nature of the surface, the active sites, and the catalytic behavior. Thus, we have developed methods to synthesize bimetallic nanoparticles with controlled particle size and controlled composition to achieve an effective link between characterization and reactivity, and between theory and experiment. We have also used ALD to modify supported metal catalysts by addition of promoters with atomic-level precision, to produce new bifunctional sites for selective catalytic transformations. We have used a variety of techniques to characterize the metal nanoparticles in our catalysts, including scanning transmission electron microcopy (STEM) to measure size and structure, energy dispersive X-ray spectroscopy (EDS) to measure atomic composition, X-ray absorption spectroscopy (XAS) to measure oxidation state and metal coordination, Fourier transform infrared spectroscopy (FTIR) to study adsorbed species, laser Raman spectroscopy to probe metal oxide promoters, and temperature programmed reaction/desorption to study the energetics of adsorption and desorption processes. We have studied our bimetallic catalysts for the selective cleavage of carbon-oxygen bonds, and we have studied the effects of adding metal oxide promoters to supported platinum and gold catalysts for water-gas shift (i.e., the production of hydrogen by reaction of carbon monoxide with water). We anticipate that the knowledge obtained from our studies will allow us to identify promising directions for new catalysts that show high activity, selectivity, and stability for important reactions, such as the conversion of biomass-derived oxygenated hydrocarbons to fuels and chemicals.
Download or read book A Comparative Study of Supported Platinum and Platinum rhenium Reforming Catalysts Using the Kinetics of Methylcyclohexane Dehydrogenation written by Laura Jean Sanborn and published by . This book was released on 1988 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book BIMETALLIC PLATINUM GOLD AND PLATINUM TIN CATALYSTS REACTIVITY ADSORPTION BEHAVIOR AND SURFACE COMPOSITION BIMETALLIC CATALYSTS written by KRISHNAN BALAKRISHNAN and published by . This book was released on 1991 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: partially reduced to a Sn (0) state. The interactions between platinum and an alumina-stabilized tin species (Sn (II), Sn (IV)) could explain the behavior of Pt-Sn/Al$\sb2$O$\sb3$ catalysts.
Download or read book The Catalysis of Uniform Metal Nanoparticles Deposited Onto Oxide Supports written by Nathan Musselwhite and published by . This book was released on 2015 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: Model materials consisting of metal nanoparticles loaded onto oxide supports were synthesized, characterized, and investigated in a number of catalytic chemical reactions. By varying the size, shape, and composition of nanoparticle, as well as the material used to support the nanoparticles, it was found that small changes to the catalyst can have enormous changes to the reaction activity and selectivity. Investigation of these carefully synthesized catalysts via in situ characterization, and reaction studies, leads to a deeper understanding of the molecular level parameters that govern catalysis. Through study of the properties of the nanoparticles it was discovered that nanoparticle size and shape have a dominant role in the chemoselective catalysis of furfural over platinum nanoparticles. When vapor phase furfural and hydrogen gas were passed over Pt nanoparticles ranging in size from 1.5 to 7.1 nm, the catalytic selectivity was found to be dominated by the size of the nanoparticle. Large nanoparticles promoted hydrogenation of furfural to furfuryl alcohol, while smaller nanoparticles favored decarbonylation to furan. The same size specific selectivity was found in the hydrogenative reforming (the transformation of hydrocarbons to branched isomers) of C6 hydrocarbons, in which Pt nanoparticle size controls isomerization selectivity. Methylcyclopentane was found to be extremely size dependent at lower temperatures (553 K). It was found that smaller sized nanoparticles favored isomer formation, while larger sizes catalyzed the aromatization reaction more efficiently. n-hexane was found to be much less dependent on particle size, but still showed an increase in isomerization with small particles over larger sized Pt nanoparticles. The composition of PtxRh1-x bimetallic nanoparticles was also studied. These catalysts were characterized under hexane reforming conditions with Ambient Pressure X-ray Photoelectron Spectroscopy (AP-XPS), in order to find the actual surface atomic composition under real catalytic working conditions. By using AP-XPS and catalytic data in tandem, it was found that an optimum Rh loading occurred when the surface ensemble statistically favored one Rh atom surrounded by Pt atoms. By utilizing different oxide materials for catalytic supports the flow of charge can play a role in the reaction at the surface or interface in a phenomenon known as the strong metal-support interaction (SMSI). When Pt nanoparticles were loaded onto mesoporous supports made of Co3O4, NiO, MnO2, Fe2O3, and CeO2 it was found that their activity for carbon monoxide oxidation was greatly enhanced relative to the support alone or Pt loaded onto inert mesoporous silica. This finding demonstrates that the interface of the metallic Pt nanoparticle and the oxide support is able to produce turnovers that are orders of magnitude higher than the two materials separately. When the same type of experiments were investigated with n-hexane as the reactant and macroporous Al2O3, TiO2, Nb2O5, Ta2O5, and ZrO2 were utilized as supports, it was found that the reaction selectivity was greatly altered depending on the catalytic support material. TiO2, Nb2O5, and Ta2O5 (all of which are strong Lewis acids) were found to be much more selective for isomer production than the standard SiO2 mesoporous silica supported Pt nanoparticle catalyst. Finally, an acidified mesoporous silica material was utilized as the support. This material was synthesized by using AlCl3 to modify the surface of mesoporous silica. This support was found to have no activity for hexane isomerization alone. However, when Pt nanoparticles were supported on the material, the activity and isomer selectivity in hexane reforming was increased several orders of magnitude as compared to the same nanoparticles supported on unmodified mesoporous silica. This dissertation builds on the existing knowledge of known concepts in catalysis science such as structure sensitive reactions, the metal-support interaction, and acid-base chemistry. The results show how small changes in the active sites of a catalyst can create large changes in the catalytic chemistry. This research demonstrates how careful material control, characterization and reaction study can help to elucidate the molecular level components necessary to design efficient catalysts.
