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Author : David William James
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (111 download)
Download or read book Selective Propane Oxidation on Mixed Metal Oxide Catalysts written by David William James and published by . This book was released on 2002 with total page 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.
Author : Xin Li
Publisher :
ISBN 13 : 9781124883106
Total Pages : pages
Book Rating : 4.8/5 (831 download)
Download or read book Investigation of M1 Phase Molybdenum Based Mixed Metal Oxide Catalysts for Selective Oxidation of Propane written by Xin Li and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Acrylic acid and acrylonitrile are important intermediates for producing a number of common chemicals and materials used in paints, adhesives, plastics, fibers, etc. Traditionally, their production has relied on propylene feedstocks, and replacing propylene with the cheaper and more abundant propane as the raw material has attracted a lot of research interest during the past two decades. Several promising catalysts have been discovered, and to date, Mo-V-Nb-Te-O mixed metal oxides are the most efficient for both propane oxidation to acrylic acid and ammoxidation to acrylonitrile. Two orthorhombic phases named M1 and M2 have been identified as the major components, and M1 is generally considered the key factor for propane activation. In particular, the [001] face of the M1 structure has been proposed to provide active centers and the valence distribution on [001] face is believed to play an important role in determining the reaction mechanism. However, the detailed mechanism is not fully understood. This has limited opportunities to further improve catalysts performance or design better catalysts by rational means. This absence can be related to the past failure of generating M1 phase alone in synthesis, and many catalysts studied previously were actually mixtures. Thus, in this work, we carried out investigations of the highly pure M1 catalyst focusing on the synthesis, catalytic behavior, and structural model development. The hydrothermal method has been shown to yield M1 phase with high purity at the expense of a more complicated procedure. The simple slurry method was used by us to synthesize catalyst samples. It is found that, besides M1 and M2, tellurium molybdate TeMo 5 O 16, V-substituted Mo 5 O 14 or (V, Mo) 5 O 14, and Mosubstituted V 2 O 5 or (Mo, V) 2 O 5 are also often formed together. The final phase composition can be significantly affected by nominal metal composition, slurry pH, calcination heating rate, etc. And the relative amount of each phase under different conditions can be directly correlated with respective V/Mo and Te/Mo ratios. Further, an additional purification step where the sample mixture is washed by H 2 O 2 solution was studied, and it is observed that concentrated hydrogen peroxide offers the most effective removal of undesired phases. A complete procedure for obtaining M1 phase in high purity has been developed. Synthesized M1 catalysts were characterized by EDS and XPS, and results suggest that the M1 structure shows high chemical flexibility and can contain vanadium to quite different levels depending on the nominal metal stoichiometry in the slurry. In particular, it is seen that the more vanadium in the slurry, the more vanadium in the final M1 structure. Additionally, no significant difference between the surface and the bulk was observed with respect to metal composition.
Download or read book Role of Constituent Elements in Propane Oxidation Over Mixed Metal Oxides written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently discovered multi-component Mo-V-Te-Nb-O catalysts contain so-called "M1" and "M2" phases with orthorhombic and hexagonal structures, respectively, proposed to be active and selective in propane (am)oxidation to acrylic acid and acrylonitrile. The elemental compositions, metal oxidation states and catalytic functions of V, Mo and Te in the surface region of the model orthorhombic (M1) Mo-V-Te-O system were examined employing low energy ion scattering and X-ray photoelectron spectroscopy. These findings suggested that the bulk Mo-V-Te-O structure functions as a special support for the unique active and selective surface monolayer in propane oxidation to acrylic acid. Propane oxidation to acrylic acid over pure phases indicated that M1 phase is the selective phase while M2 is the more active phase. The bulk Mo-V-O catalysts (orthorhombic phase) promoted with sub-monolayer quantities of surface Te, Nb and Sb oxides were further investigated to elucidate the roles of the constituent oxides in selective propane oxidation.
Author :
Publisher :
ISBN 13 :
Total Pages : 189 pages
Book Rating : 4.:/5 (227 download)
Download or read book Mesoporous and Macroporous Mixed Metal Oxide MoVTeNbOx Catalysts for Propane (amm) Oxidation written by and published by . This book was released on 2008 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Approximately 5 million metric tons of acrylonitrile are produced worldwide annually for the manufacture of acrylic fibers, copolymers and reinforced carbon fibers. There is currently intense commercial interest in developing a new catalytic process for acrylonitrile production via propane ammoxidation employing multicomponent mixed metal oxides, which would replace the existing propylene ammoxidation technology. This new technology is expected to lower the production cost by 30% as compared to the existing process because of the lower cost of propane and increased production of valuable co-products, such as acetonitrile. The key to the success of this important technology is the development of novel mixed metal oxide catalysts that can selectively ammoxidize propane to acrylonitrile. Recent developments in macroscale and mesoscale structure-directed self-assembly offer many attractive possibilities for the molecular design of novel catalytic mixed metal oxides. The present work describes the development of novel synthesis approaches for macroporous and mesoporous mixed metal MoVTe(Sb)NbOx catalysts displaying ordered porous structures, high surface areas, flexible compositions and improved thermal stability for propane ammoxidation. This research began with systematic exploration of synthesis of mesoporous Nb2O5 oxides as a departure point in the subsequent synthesis of mixed M-Nb-O (M=Mo, V, Te, Sb) oxides employing Nb2O5 as the major component or the catalytic support. Nb2O5 was chosen for this study as the most stable metal oxide possessing the highest Tammann temperature among all constituent metal oxides (MoOx, VOx, TeOx and SbOx). Thermally stable (up to 500 °C) and well-defined two-dimensional hexagonal mesostructured niobium oxides were obtained possessing the surface areas of up to 210 m2/g. The pore size of mesoporous niobium oxides was for the first time tuned in a wide range from 4.6 to 21 nm by varying synthesis conditions. As compared with previous studies, mesoporous niobium oxides with tunable pore sizes obtained in this work possessed more attractive pores structures which make them promising as catalytic supports or a major component in the synthesis of improved MoVTeNbOx catalysts for selective (amm)oxidation of propane. Thermally stable mesoporous binary (Nb-M-O, M=Mo, V, or Sb), multicomponent (MNbOx, M=Mo+V+Te) and supported (M/Nb, M=Mo+V+Te+Nb) mixed metal oxide catalysts were for the first time synthesized by evaporation-induced self-assembly and incipient-wetness impregnation techniques. These mixed metal oxide phases displayed good thermal stability of amorphous inorganic wall (up to 400°C), large pore sizes (5-23 nm), high surface areas (up to 232 m2/g) and flexible inorganic wall compositions. Improved dispersion of active components in the Nb2O5 matrix and over the Nb2O5 support was observed. However, the desirable M1 phase was not observed in the products of thermal transformation of these mesoporous mixed metal oxides probably due to insufficient thickness of inorganic walls in these phases. In order to investigate nucleation of the catalytic M1 phase and further improve the thermal stability of the ordered porous structure, MoVTeNbOx phases displaying both macroporous and mesoporous structures were prepared by a dual templating approach employing colloidal arrays of polystyrene spheres and non-ionic surfactants. The MoVTeNbOx phases possessing such dual porosity were obtained after polystyrene spheres and non-ionic surfactants were removed in a low temperature calcination step. These hierarchical MoVTeNbOx phases displaying bimodal pore structure transformed into macroporous rutile phase possessing nanocrystalline inorganic walls at high temperature. These MoVTeNbOx rutile phases possessed high surface areas (70 m2/g), desirable pore architectures, robust nanocrystalline inorganic walls and enhanced thermal stability (up to 600 °C). Although these macroporous MoVTeNbOx rutile catalysts displayed lower activity in propane ammoxidation and lower acrylonitrile selectivity in propane ammoxidation as compared to the active and selective M1 phase, the novel synthesis method reported in these studies represents a promising general approach to design novel complex mixed metal oxides for a wide range of applications in selective oxidation catalysis.
Author : David William James
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (83 download)
Download or read book Selective Propene Oxidation on Mixed Metal Oxide Catalysts written by David William James and published by . This book was released on 2002 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jacques C. Vedrine
Publisher : Elsevier
ISBN 13 : 0128116323
Total Pages : 620 pages
Book Rating : 4.1/5 (281 download)
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
Author :
Publisher :
ISBN 13 : 9789162881412
Total Pages : 73 pages
Book Rating : 4.8/5 (814 download)
Download or read book Selective Oxidation Over Mixed Metal Oxide Catalysts written by and published by . This book was released on 2010 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Thomas Edward Davies
Publisher :
ISBN 13 :
Total Pages : 356 pages
Book Rating : 4.:/5 (87 download)
Download or read book Metal Oxide Catalysts for the Low Temperature Selective Oxidation of Propane to Iso-propanol written by Thomas Edward Davies and published by . This book was released on 2006 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Adam Bielanski
Publisher : CRC Press
ISBN 13 : 1482293285
Total Pages : 489 pages
Book Rating : 4.4/5 (822 download)
Download or read book Oxygen in Catalysis written by Adam Bielanski and published by CRC Press. This book was released on 1990-11-29 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: A description of catalytic systems commonly used as model systems in the laboratory and as industrial catalysts in large-scale operations, and a discussion of the mechanisms operating in these reactions. Attempts to describe the elementary steps by quantum chemical methods are also shown, as are rec
Author : Jim Sipho Motshweni
Publisher :
ISBN 13 :
Total Pages : 382 pages
Book Rating : 4.:/5 (225 download)
Download or read book Synthesis of Mixed Metal Oxides for Use as Selective Oxidation Catalysts written by Jim Sipho Motshweni and published by . This book was released on 2007 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (16 download)
Download or read book Surface Termination of M1 Phase and Rational Design of Propane Ammoxidation Catalysts written by and published by . This book was released on 2015 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final report describes major accomplishments in this research project which has demonstrated that the M1 phase is the only crystalline phase required for propane ammoxidation to acrylonitrile and that a surface monolayer terminating the ab planes of the M1 phase is responsible for their activity and selectivity in this reaction. Fundamental studies of the topmost surface chemistry and mechanism of propane ammoxidation over the Mo-V-(Te,Sb)-(Nb,Ta)-O M1 and M2 phases resulted in the development of quantitative understanding of the surface molecular structure – reactivity relationships for this unique catalytic system. These oxides possess unique catalytic properties among mixed metal oxides, because they selectively catalyze three alkane transformation reactions, namely propane ammoxidation to acrylonitrile, propane oxidation to acrylic acid and ethane oxidative dehydrogenation, all of considerable economic significance. Therefore, the larger goal of this research was to expand this catalysis to other alkanes of commercial interest, and more broadly, demonstrate successful approaches to rational design of improved catalysts that can be applied to other selective (amm)oxidation processes.
Download or read book Peau de fleur written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Daniel Duprez
Publisher : World Scientific
ISBN 13 : 1783263342
Total Pages : 1035 pages
Book Rating : 4.7/5 (832 download)
Download or read book Handbook Of Advanced Methods And Processes In Oxidation Catalysis: From Laboratory To Industry written by Daniel Duprez and published by World Scientific. This book was released on 2014-07-24 with total page 1035 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a comprehensive overview of the most recent developments in both total oxidation and combustion and also in selective oxidation. For each topic, fundamental aspects are paralleled with industrial applications. The book covers oxidation catalysis, one of the major areas of industrial chemistry, outlining recent achievements, current challenges and future opportunities. One distinguishing feature of the book is the selection of arguments which are emblematic of current trends in the chemical industry, such as miniaturization, use of alternative, greener oxidants, and innovative systems for pollutant abatement. Topics outlined are described in terms of both catalyst and reaction chemistry, and also reactor and process technology.
Author : Christian Hess
Publisher : Royal Society of Chemistry
ISBN 13 : 1847559875
Total Pages : 453 pages
Book Rating : 4.8/5 (475 download)
Download or read book Nanostructured Catalysts written by Christian Hess and published by Royal Society of Chemistry. This book was released on 2011-07-22 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a comprehensive up-to-date summary of the existing information on the structural/electronic properties, chemistry and catalytic properties of vanadium and molybdenum containing catalysts. It discusses the importance of nanoscience for the controlled synthesis of catalysts with functional properties and introduces the necessary background regarding surface properties and preparation techniques, leading from a textbook level to the current state of knowledge. Then follows an extensive survey and analysis of the existing open and patent literature - an essential knowledge source for the development of the new generation of partial oxidation catalysts. Important examples from current research on partial oxidation reactions are reviewed from experts in the field. The next chapter discusses the importance of 2- and 3-dimensional model systems for a fundamental understanding of the structure of transition metal oxide catalysts and its correlation to reactivity. Finally, an outlook on research opportunities within the area of partial oxidation reactions is presented.
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ISBN 13 :
Total Pages : 12 pages
Book Rating : 4.:/5 (719 download)
Download or read book Sextus liber Decretalium casus litterales et notabilia domini Helie Regnier complexus, cum additionibus ex novella Johannis Andree depromptis written by and published by . This book was released on 1511 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Barbara K. Warren
Publisher :
ISBN 13 :
Total Pages : 472 pages
Book Rating : 4.3/5 (91 download)
Download or read book Heterogeneous Hydrocarbon Oxidation written by Barbara K. Warren and published by . This book was released on 1996 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compares and contrasts complete combustion and partial oxidation. Critically reviews the latest theories on oxidation, and the factors that determine selectivity. Presents the latest advances in alkane oxidation, including methane activation. Describes novel methods of catalyst preparation and characterization. Provides examples of oxidation by nontraditional oxidants like ozone, hydrogen peroxide, sulfates/nitrates, and light.
