Download or read book Effect of the Structure of Bi Mo Catalysts on Their Activity in the Propylene Oxidation Reaction written by M. M. Agaguseynova and published by . This book was released on 1977 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Toward a Molecular Level Understanding of Mixed Metal Oxide Oxidation Catalysts written by Andrew Getsoian and published by . This book was released on 2013 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: The selective oxidation and ammoxidation of light olefins comprises a 5 million ton per year industry, and is responsible for making possible products from nitrile rubber to Plexiglas to acrylic paint. The industrial catalyst of choice for such reactions is based on bismuth molybdate, and was first patented in the 1950s. In the intervening decades, a significant body of research has been done on bismuth molybdate-based catalysts, and yet a surprising amount is still not known about how these catalysts work. This Thesis has focused primarily on developing new methods for studying bismuth molybdates and related catalysts in order to gain new insight into the means by which the physical and electronic structures of the active sites in these catalysts give rise to their catalytic activity. The mechanism by which propene is oxidized on the (010) surface of Bi2Mo3O12 has been investigated using the RPBE+U variety of density functional theory (DFT). The location of the active site was determined, and the calculated barrier for the rate-determining step at this site found to be in good agreement with experimental results. Calculations revealed the essential roles of bismuth and molybdenum in providing the geometric and electronic structure responsible for catalytic activity at the active site, and suggested that catalytic activity could be further enhanced by substitution with a more reducible element. In order to accurately model substitution of an additional reducible element in to Bi2Mo3O12 using DFT, more sophisticated approaches than RPBE+U were required. Two more advanced density functionals, M06-L and HSE, were examined. The HSE functional was found to be too expensive for practical use on extended systems like bismuth molybdate catalysts. The accuracy of the M06-L functional for lattice constants and geometries, reaction energies and barriers, electronic structures, and non-covalent interactions was investigated, and compared results from the RPBE+U method. The M06-L functional was found to be superior to RPBE+U for lattice constants, reaction energies, and non-covalent interactions, and as good as or better than RPBE+U for electronic structures. Use of the M06-L functional was therefore determined to be preferable to use of RPBE+U for use in the study of substituted bismuth molybdate catalysts. Calculations employing the M06-L functional were combined with physical characterization using diffuse reflectance UV-VIS, x-ray photoelectron, and x-ray near edge absorption spectroscopies in order to understand the effect of substitution of vanadium for molybdenum on the activation energy for propene oxidation in catalysts of formula Bi1-x/3V1-xMoxO4. In these catalysts, substitution of vanadium for molybdenum has been observed to lower the apparent activation barrier for propene oxidation. It was found that the lower activation barrier for propene oxidation over mixed vanadate-molybdate catalysts is a consequence of the smaller difference between the catalyst conduction band edge energy and the energy level of the highest occupied molecular orbital in propene. The lower conduction band edge energy in mixed vanadate-molybdate catalysts is related to the energies of and degrees of mixing between the V 3d and Mo 4d orbitals comprising the conduction band. Both of these observations suggest general principles that may be of relevance to a variety of mixed metal oxide catalyst systems. An improved procedure for synthesizing bismuth molybdate and bismuth vanadate catalysts was also developed. This procedure involved a two step templating process: a structured mesoporous carbon was templated from KIT-6 or MCM-48 mesoporous silica, and the structured mesoporous carbon in turn used as a template during synthesis of the metal oxide catalyst. Catalysts produced by the double templating process had surface areas of 14-17 m2/g, a large improvement on the

Download or read book Catalytic Partial Oxidation of Propylene to Acrolein written by Hamzah Fansuri and published by . This book was released on 2005 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reduction-reoxidation of bismuth molybdate is controlled by the diffusion of oxygen ions in the lattice, because the reduction sites do not have to be adjacent to the oxidation sites. The oxygen diffusion rate is in turn controlled by how mobile the lattice oxygen ions are. Hence, the mobile oxygen ions discussed earlier control the catalyst activity in catalysing the reaction of propylene partial oxidation. The examination of several reaction mechanism models has given further evidence that the propylene partial oxidation to acrolein occurs via the redox mechanism. In this mechanism, the rate of acrolein formation depends on the degree of fully oxidised sites in the bismuth molybdate. The oxidised sites affect the apparent reaction orders in propylene and oxygen and thus control the kinetics of partial oxidation of propylene to acrolein. The more easily the reduced catalysts are reoxidised, the more active the catalysts in converting propylene to acrolein. A set of reaction steps has been proposed, which adequately reassembles the reaction mechanism. Side product reactions are also identified and included in the mechanisms. The present thesis has revealed a much detailed insight into the role of lattice oxygen in the catalytic partial oxidation of propylene to acrolein over bismuth molybdates and established the relationship between structure and activity and selectivity of the catalyst. This work has laid a foundation for future catalyst design to be based on structural knowledge of the catalysts.

Download or read book Metal Oxides in Heterogeneous Catalysis written by Jacques C. Vedrine and published by Elsevier. This book was released on 2018-01-11 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal Oxides in Heterogeneous Catalysis is an overview of the past, present and future of heterogeneous catalysis using metal oxides catalysts. The book presents the historical, theoretical, and practical aspects of metal oxide-based heterogeneous catalysis. Metal Oxides in Heterogeneous Catalysis deals with fundamental information on heterogeneous catalysis, including reaction mechanisms and kinetics approaches.There is also a focus on the classification of metal oxides used as catalysts, preparation methods and touches on zeolites, mesoporous materials and Metal-organic frameworks (MOFs) in catalysis. It will touch on acid or base-type reactions, selective (partial) and total oxidation reactions, and enzymatic type reactions The book also touches heavily on the biomass applications of metal oxide catalysts and environmentally related/depollution reactions such as COVs elimination, DeNOx, and DeSOx. Finally, the book also deals with future trends and prospects in metal oxide-based heterogeneous catalysis. - Presents case studies in each chapter that provide a focus on the industrial applications - Includes fundamentals, key theories and practical applications of metal oxide-based heterogeneous catalysis in one comprehensive resource - Edited, and contributed, by leading experts who provide perspectives on synthesis, characterization and applications

Download or read book Advances In Catalyst Design Vol 2 Proceedings Of The 2nd Workshop On Catalyst Design written by Mauro Graziani and published by World Scientific. This book was released on 1993-09-30 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: The workshop organized by the international centre for science and technology provided an occasion for researchers active both in homogeneous and heterogeneous catalysis to meet and look for common interpretations and a common language.

Download or read book Bulletin written by Sekiyu Gakkai (Japan) and published by . This book was released on 1972 with total page 890 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Structure reactivity Relationships for Propane Oxidation Over Model Mixed Oxide Catalysts written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixed Mo-V-Sb-Nb and Mo-V-Te-Nb oxides were recently discovered as highly active and selective catalysts for the propane oxidation to propylene and oxygenates, i.e. acrolein and acrylic acid. Fundamental information is needed for understanding the bulk and surface molecular structure-activity/selectivity relationships and providing rules of rational design of improved mixed metal oxide catalysts for the selective oxidation of propane. The phase composition and catalytic activity of the model Mo-V-Sb-Nb-O system strongly depended on the synthesis route and composition. A number of distinct solid-state phases were observed in this system: Mo6V9O40, MoO3, rutile SbVO4 and the defect "Mo-V-Nb-O" phases. The kinetic studies indicated that the high selectivity to acrylic acid (2̃0 mol.%) was associated with the Mo6V9O40 and the defect "Mo-V-Nb-O" phases. The synthesis of these mixed Mo-V-Sb-Nb-O system was performed using combinatorial chemistry techniques to explore the utility of liquid phase automated synthesis for the reproducible preparation of these catalysts. This study indicated good reproducibility of phase compositions and catalytic properties and provided new insights into the transformation processes that occur in these oxides with time on stream. It was discovered in this research that the model mixed Mo-V-Te-O catalyst represents a simple model system for elucidating the molecular structure-activity/selectivity relationships in propane selective oxidation. This catalyst contains the two major crystalline phases proposed as active and selective for propane oxidation. This research elucidated the effect of the chemical composition, solution pH and thermal treatment on phase composition and catalytic performance. High resolution TEM study established the crystal structures of the hexagonal and orthorhombic phases in terms of their space groups, unit cell parameters, atomic coordinates and elemental compositions. In order to understand the role of the structure, morphology and composition of mixed Mo-V-Te-Nb-O system, novel synthesis approaches employing ordered arrays of colloidal polystyrene spheres (0.4 ưm) were successfully developed. These novel nanocrystalline catalysts with surface areas in the 80-110 m2/g range consisted of 20-50 nm particles of desirable catalytic phases and contained 6-20 nm pores. Kinetic studies demonstrated the acrylic acid yields exceeding 40 mol.% and approaching the commercial targets for the selective oxidation of propane to acrylic acid.

Download or read book Bulletin of the Japan Petroleum Institute written by Sekiyu Gakkai (Japan) and published by . This book was released on 1976 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure Activity and Selectivity Relationships in Heterogeneous Catalysis written by R.K. Grasselli and published by Elsevier. This book was released on 1991-07-09 with total page 375 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structure plays an important role in heterogeneous catalysis. It provides a framework for the arrangement and stragetic placement of key catalytic elements, hosting them in a prescribed manner so that their respective electronic properties can exhibit their desired catalytic functions and mutual interactions. Under reaction conditions these framework structures and their catalytic guests undergo dynamic processes becoming active participants of the overall catalytic process. They are not mere static geometric forms. The dynamics of catalytic structures are particularly vivid in selective oxidation catalysis where the lattice of a given catalytic solid partakes as a whole, not only its surface, in the redox processes of the reaction. The catalyst becomes actually a participating reagent. By proper choice of key catalytic elements and their host structures, preferred catalytic pathways can be selected over less desired ones. However, not only in selective redox catalysis does structure play an important role, its importance is also well documented, among others, in shape selective zeolite catalysis, enantioselective hydrogenation and hydrodesulfurization. The contributions presented in this book address the dynamic character of the solid state under catalytic reaction conditions. By relating structure to activity and selectivity in heterogeneous catalysis our understanding of such correlations has been significantly enhanced through the use of sophisticated spectroscopic means, surface science and modeling.

Download or read book The Activation of Dioxygen and Homogeneous Catalytic Oxidation written by D.H.R. Barton and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 503 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph consists of the proceedings of the Fifth International Symposium on the Activation of Dioxygen and Homogeneous Catalytic Oxidation, held in College Station, Texas, March 14-19, 1993. It contains an introductory chapter authored by Professors D. H. R. Barton and D. T. Sawyer, and twenty-nine chapters describing presentations by the plenary lecturers and invited speakers. One of the invited speakers, who could not submit a manuscript for reasons beyond his control, is represented by an abstract of his lecture. Also included are abstracts of forty-seven posters contributed by participants in the symposium. Readers who may wish to know more about the subjects presented in abstract form are invited to communicate directly with the authors of the abstracts. This is the fifth international symposium that has been held on this subject. The first was hosted by the CNRS, May 21-29, 1979, in Bendor, France (on the Island of Bandol). The second meeting was organized as a NATO workshop in Padova, Italy, June 24-27, 1984. This was followed by a meeting in Tsukuba, Japan, July 12-16, 1987. The fourth symposium was held at Balatonfured, Hungary, September 10-14, 1990. The sixth meeting is scheduled to take place in Delft, The Netherlands (late Spring, 1996); the organizer and host will be Professor R. A. Sheldon.

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 Bismuth Molybdate Catalysts for the Partial Oxidation of Propylene written by Thomas Peter Snyder and published by . This book was released on 1988 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Understanding the Partial Oxidation of Propylene Over Silver Catalysts written by Jeffrey Taylor Ranney and published by . This book was released on 1998 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book World Translations Index written by and published by . This book was released on 1994 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advanced Materials in Catalysis written by Frank Bolz and published by Elsevier. This book was released on 2013-10-22 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Materials in Catalysis is a collection of materials that discusses various catalysts. The book presents the physical and chemical properties that indicate that a particular class of materials may be of catalytic interest. The text first covers bimetallic catalysts, and then proceeds to examining the catalytic properties of compounds such as graphite intercalation compounds; oxides with the scheelite structure; and synthetic layered silicates and aluminosilicate. The book also covers reduction catalysts, biological catalysts, and monolithic catalyst supports. The selection will be of great use to students and practitioners of chemistry, particularly those who are involved in research studies that investigate materials problems in catalysis.

Download or read book An Investigation Into the Structure and Activity of Monometallic and Bimetallic Copper and Gold Catalysts for Propene Oxidation written by Charlotte Louise Bracey and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: CuAu/SiO2 catalysts were prepared in a number of ways, the main route being incipient wetness impregnation, but other methods, like deposition precipitation and high dispersion, were also used. Bimetallic and monometallic catalysts were prepared for this investigation and most were characterised by various techniques such as XRD, SEM, TPR, BET, UV visible and TEM. Theoretical and characterisation studies of CuAu catalysts have generated considerable interest. However, little research has been carried out on their catalytic activity. Therefore, propene oxidation was chosen as the principal reaction, as it was previously examined by Chimentao and group.1 This study showed that the reduction of the catalysts in H2/Ar was fundamental to alloy formation. The most active catalyst was made by a sequential procedure that deposited the copper onto the silica support by high dispersion, followed by depositing gold onto the support by deposition precipitation. The catalyst was then treated by a Sinfelt thermal treatment which involved a reduction in H2/Ar at 315oC for 2h followed by a high temperature calcination at 676oC in air for 15h. Propene oxidation was performed in the presence of hydrogen and a propene conversion of 10% was observed at 320oC, with a selectivity towards acrolein (90%) and some carbon dioxide (10%). The purpose of this study was to obtain an understanding of the nature of these CuAu/SiO2 catalysts and to determine if there were any relationship towards their activity for propene oxidation.

Download or read book Advances in Catalysis written by and published by Academic Press. This book was released on 1979-02-12 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Catalysis