Download or read book VANADIUM AND MOLYBDENUM INCORPORATED MCM 41 CATALYSTS FOR SELECTIVE OXIDATION OF ETHANOL written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT VANADIUM AND MOLYBDENUM INCORPORATED MCM-41 CATALYSTS FOR SELECTIVE OXIDATION OF ETHANOL Güçbilmez, Yeþim Ph. D., Department of Chemical Engineering Supervisor : Prof. Dr. Timur Doðu Co-Supervisor: Prof. Dr. Suna Balcý June 2005, 144 pages In this study, V-MCM-41, MCM-41 and Mo-MCM-41 catalysts were synthesized by the one-pot alkaline and acidic synthesis methods. The as-synthesized catalysts were found to have high BET surface areas (430-1450 m2/g), homogeneous pore size distributions (2-4 nm), good crystalline patterns and high metal loading levels (Metal/Si atomic ratio in the solid = 0.01-0.16) as determined by the characterization studies. MCM-41 and Mo-MCM-41 catalysts were highly active in the selective oxidation of ethanol with conversion levels of 56% and 71%, respectively, at 400oC for an O2/EtOH feed ratio of 0.5. Both catalysts had very high selectivities to acetaldehyde at temperatures below 300oC. Conversions exceeded 95% with the V-MCM-41 catalyst having a V/Si molar ratio (in the solid) of 0.04 in the temperature range of 300oC-375oC for the O2/EtOH feed ratios of 0.5-2.0. Acetaldehyde selectivities changed between 0.82-1.00 at the temperature range of 150oC-250oC. Ethylene, which is listed as a minor side product of the selective oxidation of ethanol in literature, was produced with a maximum yield of 0.66 at 400oC at the O2/EtOH feed ratio of 0.5. This yield is higher than the yields obtained in the industrial ethylene production methods such as thermal cracking and oxidative dehydrogenation of ethane. Besides, the feedstock used in this work is a non-petroleum chemical, namely ethanol, which can be produced from sugar and crop wastes by fermentation. Thus, the findings of this study are also proposed as an alternative ethylene production method from a non-petroleum reactant at lower temperatures with higher yields. ÖZ ETANOLÜN SEÇÝCÝ OKSÝDASYONUNDA KULLANILMAK ÜZERE VANADYUM VE MOLÝBDEN ÝÇEREN MCM-41 KATALÝZÖRLERÝNÝN ÜRETÝMÝ Güçbilmez, Yeþ

Download or read book Pathway and Surface Mechanism Studies of 1 3 butadiene Selective Oxidation Over Vanadium Molybdenum Oxygen Catalysts written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The partial oxidation of 1,3-butadiene has been investigated over VMoO catalysts synthesized by sol-gel techniques. Surface areas were 9-14 m2/g, and compositions were within the solid solution regime, i.e. below 15.0 mol % MoO3/(MoO3 + V2O5). Laser Raman Spectroscopy and XRD data indicated that solid solutions were formed, and pre- and post-reaction XPS data indicated that catalyst surfaces contained some V{sup +4} and were further reduced in 1,3-butadiene oxidation. A reaction pathway for 1,3-butadiene partial oxidation to maleic anhydride was shown to involve intermediates such as 3,4-epoxy-1-butene, crotonaldehyde, furan, and 2-butene-1,4-dial. The addition of water to the reaction stream substantially increased catalyst activity and improved selectivity to crotonaldehyde and furan at specific reaction temperatures. At higher water addition concentrations, furan selectivity increased from 12% to over 25%. The catalytic effects of water addition were related to competitive adsorption with various V2O5-based surface sites, including the vanadyl V=O, corner sharing V-O-V and edge sharing V-O oxygen. Higher levels of water addition were proposed to impose acidic character by dissociative adsorption. In addition, a novel combinatorial synthesis technique for VMoO was used to investigate the phase transitions of V2O5, solid solutions of Mo in V2O5, V9Mo6O40, and other reduced VMoO compounds, characterized by laser Raman spectroscopy. The natural composition gradient imposed by the sputter deposition apparatus was used to create VMoO arrays containing 225 samples ranging from 7.0-42 mol% MoO3/(V2O5 + MoO3), determined by EDS analysis.

Download or read book Selective oxidation over vanadium containing catalysts written by Philip J. Pomonis and published by . This book was released on 1977 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pathway and Surface Mechanism Studies of 1 3 butadiene Selective Oxidation Over Vanadium molybdenum oxygen Catalysts written by William David Schroeder and published by . This book was released on 2001 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: The catalytic effects of water addition were related to competitive adsorption with various V2O5-based surface sites, including the vanadyl V=O, corner sharing V-0-V and edge sharing V-0 oxygen. Higher levels of water addition were proposed to impose acidic character by dissociative adsorption. In addition, a novel combinatorial synthesis technique for VMoO was used to investigate the phase transitions Of V205, solid solutions of Mo in V205, V9Mo6040, and other reduced VMoO compounds, characterized by laser Raman spectroscopy. The natural composition gradient imposed by the sputter deposition apparatus was used to create VMoO arrays containing 225 samples ranging from 7.0 - 42 mol % Mo03/(V205 + Mo03), determined by EDS analysis.

Download or read book Metal Loaded MCM 41 Catalysts for Selective Reduction of NOx NO Tief X with Hydrocarbons written by Walter Schießer and published by . This book was released on 2000 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Partial Oxidation of Ethanol Over Vanadium Iron Antimonate Catalysts written by Boni kaKhuzwayo Mehlomakulu and published by . This book was released on 2003 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 Oxidation of Methanol Over Molybdenum vanadium Oxide Catalysts written by Mahendra Kumar Dosi and published by . This book was released on 1971 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Partial Oxidation of Methanol on Molybdenum and Vanadium Oxide Catalysts written by Raúl Miranda and published by . This book was released on 1983 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 2 written by and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vanadium Catalysis written by Manas Sutradhar and published by Royal Society of Chemistry. This book was released on 2020-11-05 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vanadium is one of the more abundant elements in the Earth’s crust and exhibits a wide range of oxidation states in its compounds making it potentially a more sustainable and more economical choice as a catalyst than the noble metals. A wide variety of reactions have been found to be catalysed by homogeneous, supported and heterogeneous vanadium complexes and the number of applications is growing fast. Bringing together the research on the catalytic uses of this element into one essential resource, including theoretical perspectives on proposed mechanisms for vanadium catalysis and an overview of its relevance in biological processes, this book is a useful reference for industrial and academic chemists alike.

Download or read book Direct Natural Gas Conversion to Value Added Chemicals written by Jianli Hu and published by CRC Press. This book was released on 2020-09-25 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct Natural Gas Conversion to Value-Added Chemicals comprehensively discusses all major aspects of natural gas conversion and introduces a broad spectrum of recent technological developments. Specifically, the book describes heterogeneous and homogeneous catalysis, microwave-assisted conversion, non-thermal plasma conversion, electrochemical conversion, and novel chemical looping conversion approaches. Provides an excellent benchmark resource for the industry and academics Appeals to experienced researchers as well as newcomers to the field, despite the variety of contributing authors and the complexity of the material covered Includes all aspects of direct natural gas conversion: fundamental chemistry, different routes of conversion, catalysts, catalyst deactivation, reaction engineering, novel conversion concepts, thermodynamics, heat and mass transfer issues, system design, and recent research and development Discusses new developments in natural gas conversion and future challenges and opportunities This book is as an excellent resource for advanced students, technology developers, and researchers in chemical engineering, industrial chemistry, and others interested in the conversion of natural gas.

Download or read book Sn MCM 41 Catalysts written by Jesse Quentin Bond and published by . This book was released on 2009 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Oxidation of Methanol Over Molybdenum vanadium Oxide Catalysts written by Mahendra Kumar Dosi and published by . This book was released on 1971 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metal Catalyzed Oxidations of Organic Compounds written by Roger Sheldon and published by Elsevier. This book was released on 2012-12-02 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal-Catalyzed Oxidations of Organic Compounds: Mechanistic Principles and Synthetic focuses on the oxidative transformations of functional groups. This book explores oxidation as being extensively used in the laboratory synthesis of fine organic chemicals and in the manufacture of large-volume petrochemicals. Organized into two parts encompassing 13 chapters, this book starts with an overview of the mechanistic principles of oxidation–reduction in biochemical, organic, and inorganic systems. This text then proceeds with a discussion of the use of molecular oxygen, hydrogen peroxide, and alkyl hydroperoxides as primary oxidants. Other chapters explore stoichiometric oxidations with metal oxidants, which include permanganate and chromic acid. This book discusses as well the synthetic applications of catalytic oxidations as well as the technology of petrochemical oxidation. The final chapter deals with the autoxidations of sulfur, phosphorus, and nitrogen compounds. This book is intended for chemists involved in organic synthesis, catalysis, and organometallic chemistry, both in academic institutions and in industrial laboratories.