Catalytic Conversion Of Carbon Monoxide And Methane Over Metal And Metal Oxide Catalysts
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Catalytic Conversion Of Carbon Monoxide And Methane Over Metal And Metal Oxide Catalysts
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Author : Wenchi Liu
language : en
Publisher:
Release Date : 2018
Catalytic Conversion Of Carbon Monoxide And Methane Over Metal And Metal Oxide Catalysts written by Wenchi Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
Catalysis is of vital importance in a wide range of areas including energy processing and chemical production. Catalytic conversion of C1 sources such as carbon monoxide and methane to make hydrocarbon fuels and oxygenated products has far reaching implications especially in the context of the gradual depletion of crude oil resource and the potential surge in the natural gas production in the coming decades. The control over reaction activity and selectivity for the conversion CO and CH4 in the Fischer–Tropsch synthesis and oxidative coupling of methane (OCM) have received tremendous attention and have been proved challenging. This dissertation focuses on the catalytic conversion of CO (Fischer–Tropsch synthesis) using supported cobalt based bimetallic nanoparticle model catalysts and the oxidative coupling of methane with noble metal promoted metal oxide catalysts. Using colloidal synthesis, a series of cobalt based bimetallic nanoparticles Co–M (M = Mn, Ru, Rh, and Re) with well-defined sizes, shapes, and compositions were obtained. Detailed synthesis procedures were presented and key synthetic parameters were discussed. The as-synthesized nanoparticles were subjected to extensive in-situ X-ray spectroscopy studies using ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and X-ray absorption spectroscopy (XAS) under catalytic relevant conditions. Composition wise, the results indicate the surface concentration of Co on the as-synthesized Co–M bimetallic particles is slightly less than the bulk atomic Co %. While oxidation treatment led to a slight increase of the surface Co, major effect was seen after the reduction treatment where surface segregation of the second metal resulted in a drastic decrease of the surface Co content. The effect is more pronounced at elevated reduction temperatures. Under reaction conditions, the surface compositions remained similar to those after the reduction treatment at high temperatures. Among the bimetallics tested, the Co–Mn system is relatively less susceptible to surface reconstructions induced by oxidation and reduction treatments. In addition, the reducibility of Co was also shown to be modified depending on the second metal present and Re was proved to be most efficient in leading to a facile reduction of Co. Catalytic performance of the bimetallic catalysts supported on mesoporous silica MCF–17 indicates a positive effect in the catalytic activity for Co–Rh and Co–Mn systems, while Co–Re and Co–Cu showed decreased activity. Less pronounced promotion effect of the second metal on the product distribution was observed with only a slight increase in the selectivity towards C5+ products. The selectivities for CH4 and C5+ of the various Co–M bimetallic catalysts generally resemble those of pure Co catalysts. Although in extremely low selectivity, alcohols were also formed with Co–Rh and Co–Cu bimetallic catalysts. The appearance of longer chain alcohol such as propanol, which was not present for pure Co catalysts, is an evidence for potential synergistic promotion. For oxidative coupling of methane (OCM), the promotion effect of noble metals (Pt, Ir, and Rh) on the performance of MnxOy-Na2WO4/MCF–17 catalysts was investigated. The introduction of noble metals had little effect on the surface area and phase composition of the original catalyst but led to a more reduced nature of the surface oxide species. Catalytic study revealed an enhanced selectivity towards both C2 and C3 hydrocarbons as compared to the undoped MnxOy-Na2WO4/MCF–17 catalyst in the order of Rh-doped > Ir-doped > Pt-doped samples together with a lower olefin to paraffin ratio. A more optimized strength of interaction between the carbon intermediates and the catalyst surface was suggested, which in combination with the improved reducibility of Mn and W species are believed to be responsible for the improved performance. In addition, monodispersed leaf-like manganese–tungsten–oxide (Mn–W–Ox) nanoparticles and hydroxylated hexagonal boron nitride (h-BN) were synthesized and used as novel catalysts in OCM reaction. Preliminary results indicate that the MCF–17 supported Mn–W–Ox nanoparticle catalyst showed a CH4 conversion of 5.4% and C2 selectivity of 42% with good stability over time. On the other hand, hydroxylated h-BN exhibited good activity (~20% CH4 conversion) with moderate selectivity towards C2 hydrocarbons (20%–30%). However, the hydroxylated h-BN catalysts faced serious deactivation, which was not eliminated by lowering the reaction temperature or the oxygen concentration in the reaction gas feed.
Catalysis For C1 Chemistry Oxidative Coupling Of Methane Using Nanofiber Catalysts And Discovery Of Catalysts For Atmospheric Reduction Of Co2 To Methanol
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Author : Bahman Zohour
language : en
Publisher:
Release Date : 2017
Catalysis For C1 Chemistry Oxidative Coupling Of Methane Using Nanofiber Catalysts And Discovery Of Catalysts For Atmospheric Reduction Of Co2 To Methanol written by Bahman Zohour and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
The goal of this research is to explore novel catalytic material and systems for effective conversion of C1 feed. Catalysis of C1 chemistry is of critical importance for the clean production of fuels and chemicals and future energy sustainability. Herein, two processes were studied: In the first section, a comprehensive study of oxidative coupling of methane (OCM) using novel nanofiber catalysts of mixed metal oxides was undertaken and in the second section, direct catalytic conversion of carbon dioxide (CO2) to methanol was studied, which resulted in discovery of a superior catalytic system for CO2 hydrogenation to methanol. Section 1: Utilization of natural gas as an alternate chemical feedstock to petroleum has been a highly desirable but difficult goal in industrial catalysis. Accordingly, there has been a substantial interest in the oxidative coupling of methane (OCM), which allows for the direct catalytic conversion of methane into economically valuable C2+ hydrocarbons. OCM is a complex reaction process involving heterogeneous catalysis intricately coupled with gas phase reactions; hence, despite decades' worth of research, it has yet to be commercialized. The lack of progress in OCM is primarily due to the following reasons: 1. The absence of a highly active and robust catalyst that can operate at lower temperatures; and 2. Our inadequate understanding of the underlying detailed chemical kinetics mechanism (DCKM) of the OCM process, which impedes the undertaking of quantitative simulations of novel reactor configurations and/or operating strategies. To address these issues, we undertook the following program of studies: 1. Further improved the synthesis of novel nanofiber catalysts by electrospinning, building on the early discovery that La2O3-CeO2 nanofibers were highly active and robust OCM catalysts; 2. Applied our novel microprobe sampling system to OCM reactors for the acquisition of spatially resolved species concentration and temperatures profiles within the catalytic zone. Our novel sampling approach led to the important discovery that H2 is produced very early in the OCM catalytic zone, an observation that was completely missed in all prior studies. The application of our novel microprobe system to a dual-bed OCM reactor also demonstrated the feasibility to significantly improve C2+ product yields to 21% (from 16% for single bed) which we plan to further improve by considering more sequential beds; 3. Outlined development and validation of new generation of DCKM for the OCM process using the high-information content of spatial concentration profiles obtained in part 2. Most importantly, to improve the current DCKM literature by considering surface reactions that result in early H2 formation. Validated DCKM represent highly valuable numerical tools that allow for the prediction of the OCM performance of different reactor configurations operating under a broad range of conditions, e.g. high pressures, porous wall reactors etc. Consequently, this new generation of comprehensive DCKM based on the sampling profiles, detailed in this report, will be of considerable use in improving the yields of useful products in the OCM process; 4. Explore novel conditions that include oxygen-feed distributed packed bed OCM reactors and coupled catalytic and non-thermal plasma OCM reactors, again to further push the yields for useful C2+ products. The details of the proposed approach for implementing such reactor configurations and development of a new generation of DCKM for the OCM process is outlined in the future work, Chapter 4, of section 1 of the report. Section 2: Direct catalytic conversion of carbon dioxide to liquid fuels and basic chemicals, such as methanol, using solar-derived hydrogen at or near ambient pressure is a highly desirable goal in heterogeneous catalysis. When realized, this technology will pave the way for a sustainable society together with decentralized power generation. Here we report a novel class of holmium (Ho) containing multi-metal oxide Cu catalysts discovered through the application of high-throughput methods. In particular, ternary systems of Cu-GaOx-HoOy > Cu-CeOx-HoOy ~ Cu-LaOx-HoOy supported on -Al2O3 exhibited superior methanol production (10x) with less CO formation than previously reported catalysts at atmospheric pressure. Holmium was shown to be highly dispersed as few-atom clusters, suggesting that the formation of tri-metallic sites could be the key for the promotion of methanol synthesis by Ho.
Catalyst For The Methanation Of Carbon Monoxide In Sour Gas
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Author :
language : en
Publisher:
Release Date : 1985
Catalyst For The Methanation Of Carbon Monoxide In Sour Gas written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with categories.
The invention involves the synergistic effect of the specific catalytic constituents on a specific series of carriers for the methanation of carbon monoxide in the presence of sulfur at relatively high temperatures and at low steam to gas ratios in the range of 0.2:1 or less. This effect was obtained with catalysts comprising the mixed sulfides and oxides of nickel and chromium supported on carriers comprising magnesium aluminate and magnesium silicate. Conversion of carbon monoxide to methane was in the range of from 40 to 80%. Tests of this combination of metal oxides and sulfides on other carriers and tests of other metal oxides and sulfides on the same carrier produced a much lower level of conversion.
Methane Conversion By Oxidative Processes
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Author : Wolf
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-11-11
Methane Conversion By Oxidative Processes written by Wolf and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-11-11 with Technology & Engineering categories.
A reasonable case could be made that the scientific interest in catalytic oxidation was the basis for the recognition of the phenomenon of catalysis. Davy, in his attempt in 1817 to understand the science associated with the safety lamp he had invented a few years earlier, undertook a series of studies that led him to make the observation that a jet of gas, primarily methane, would cause a platinum wire to continue to glow even though the flame was extinguished and there was no visible flame. Dobereiner reported in 1823 the results of a similar investigation and observed that spongy platina would cause the ignition of a stream of hydrogen in air. Based on this observation Dobereiner invented the first lighter. His lighter employed hydrogen (generated from zinc and sulfuric acid) which passed over finely divided platinum and which ignited the gas. Thousands of these lighters were used over a number of years. Dobereiner refused to file a patent for his lighter, commenting that "I love science more than money." Davy thought the action of platinum was the result of heat while Dobereiner believed the ~ffect ~as a manifestation of electricity. Faraday became interested in the subject and published a paper on it in 1834; he concluded that the cause for this reaction was similar to other reactions.
Conversion Of Methane And Carbon Dioxide On Porous Catalytic Membranes
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Author : Alexey Fedotov
language : en
Publisher:
Release Date : 2009
Conversion Of Methane And Carbon Dioxide On Porous Catalytic Membranes written by Alexey Fedotov and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
This study reports the development of a new process to convert methane and carbon dioxide (dry methane reforming - DMR) into valuable products such as syngas from non-oil resources. The practical interest is to produce syngas from carbon containing exhaust industrial gases. This process uses membrane catalytic systems (MCS) that support heterogeneous catalytic reactions in gaseous phase in ceramic micro-channels. The active surface of the catalysts formed inside the micro-channels is low in term of area, but it is characterized by a high value of the catalyst surface/volume ratio, which induces a high efficiency of heterogeneous catalysis. The SMC are formed from alkoxy derivatives and precursor metal complex containing between 0.008 and 0.055% by weight of nano-components mono-and bimetallic active distributed evenly in the channels. For systems [La-Ce] -MgO-Ti02/Ni-Al and Pd-Mn-Ti02/Ni-Al, productivities of 10500 and 7500 l/h · dm3 membr. were respectively obtained by RSM at 450°C with a composition of syngas H2/?? ranging from 0.63 to 1.25 and a conversion rate of 50% with a CH4/CO2 (1/1) feed. Thus the CMS is an order of magnitude more efficient than a fixed bed reactor of the same catalyst. The MDR is initiated by the oxidation of CH4 by structural oxygen of metal oxides available on the surface, and the CO2 reacts with the finely divided carbon arising from the dissociation of CH4. A catalytic synergy has been demonstrated for the system Pd-Mn. This CMS, having 108 pores per cm2 of surface, can be considered as a set of nano reactors. Thus this new approach is very promising for industry (synthesis of olefins, uses of biomass).
Conversion Of Carbon Dioxide Into Hydrocarbons Vol 1 Catalysis
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Author : Inamuddin
language : en
Publisher: Springer Nature
Release Date : 2020-01-01
Conversion Of Carbon Dioxide Into Hydrocarbons Vol 1 Catalysis written by Inamuddin and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-01-01 with Science categories.
This book presents the catalytic conversion of carbon dioxide into various hydrocarbons and other products using photochemical, electrochemical and thermo-chemical processes. Products include formate, formic acid, alcohols, lower and higher hydrocarbons, gases such as hydrogen, carbon monoxide and syngas.
Photocatalytic Conversion Of Methane And Reduction Of Co2 With H2o
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Author : Xiang Yu
language : en
Publisher:
Release Date : 2019
Photocatalytic Conversion Of Methane And Reduction Of Co2 With H2o written by Xiang Yu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with categories.
Photocatalysis is one of the key technologies for clean energy and environmental applications. The number of applications based on photocatalysis has increased dramatically for the past two decades. Photocatalytic activation of C-H bonds is an emerging field. Methane is a promising source of energy with a huge reserve and is considered to be one of the alternatives to non-renewable petroleum resources because it can be converted to valuable hydrocarbon feedstocks and hydrogen through appropriate reactions. However, due to its high stability, high energy is usually consumed for its conversion, which remains a problem to be solved. Methane conversion and reaction mechanism occurring on metal-heteropolyacid-titania nanocomposites were investigated in Chapters 3 and 4. Oxidation of methane has been carried out for more than a century. Since oxygen is a very reactive molecule, methane can react very rapidly with molecular oxygen and is prone to total oxidation till CO2. Therefore, it is difficult to obtain a desired product with high yield and high selectivity. We report here direct and selective photocatalytic highly-selective oxidation of methane to carbon monoxide under ambient conditions. The composite catalysts on the basis of zinc, tungstophosphoric acid and titania exhibit exceptional performance in this reaction, high carbon monoxide selectivity and quantum efficiency of 7.1% at 362 nm. The reaction is consistent with the Mars-Van Krevelen type sequence and involves formation of the surface methoxy-carbonates as intermediates and zinc oxidation-reduction cycling. In the past few decades, extensive research has focused on the direct conversion of methane to alcohols or higher hydrocarbons. The current processes of converting methane to alcohols or olefins are complex and expensive, because they require an intermediate step of reforming methane to syngas. Although the direct conversion of methane to more valuable products has significant environmental and potential commercial value, there is no commercial scale process available. We uncovered highly selective (>90%) quantitative photochemical direct conversion of methane to ethane at ambient temperature over silver-heteropolyacid-titania nanocomposites. The ethane yield from methane reaches 9 % on the optimized materials. High quantum efficiency, high selectivity and significant yield of ethane combined with excellent stability are major advantages of methane quantitative synthesis from methane using the photochemical looping approach. The rise in atmospheric carbon dioxide and the depletion of fossil fuel reserves have raised serious concerns about the subsequent impact of CO2 on the global climate and future energy supply. The use of abundant solar energy to convert carbon dioxide into fuel, such as carbon monoxide, methane or methanol, solves both problems simultaneously and provides a convenient method of energy storage. Chapter 5 addresses a new efficient catalyst for selective CO2 to CO conversion. The zinc containing phosphotungstic acid-titania nanocomposites exhibited exceptional high activity reaching 50 μmol CO/g·h and selectivity (73%) in the CO2 photocatalytic reduction to CO in the presence of water. The in-situ IR experiments suggest that reaction involves zinc bicarbonates containing hydroxyl groups. The decomposition of these zinc bicarbonate species under irradiation leads to the selective production of carbon monoxide and oxygen. In photocatalytic reactions, the difference in catalyst morphology usually has a significant effect on the photocatalytic performance. Chapter 6 studied the effect of monoclinic bismuth vanadate (BiVO4) crystals with controlled ratio of {010} and {110} facets for photocatalytic reduction of CO2 by H2O. The reaction under irradiation is significantly enhanced by selective photo-deposition of Cu and Co co-catalysts over different facets providing Z-scheme charge flow.
Annual Reports In Computational Chemistry
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Author :
language : en
Publisher: Elsevier
Release Date : 2015-11-29
Annual Reports In Computational Chemistry written by and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-11-29 with Science categories.
Annual Reports in Computational Chemistry provides timely and critical reviews of important topics in computational chemistry as applied to all chemical disciplines. Topics covered include quantum chemistry, molecular mechanics, force fields, chemical education, and applications in academic and industrial settings. Focusing on the most recent literature and advances in the field, each article covers a specific topic of importance to computational chemists. Quantum chemistry Molecular mechanics Force fields Chemical education and applications in academic and industrial settings
Catalytic Reaction Synthesis For The Partial Oxidation Of Methane To Formaldehyde
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Author : Maria-Guadalupe Cardenas-Galindo
language : en
Publisher:
Release Date : 1993
Catalytic Reaction Synthesis For The Partial Oxidation Of Methane To Formaldehyde written by Maria-Guadalupe Cardenas-Galindo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.
Catalysis By Materials With Well Defined Structures
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Author : Zili Wu
language : en
Publisher: Academic Press
Release Date : 2015-03-26
Catalysis By Materials With Well Defined Structures written by Zili Wu and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-03-26 with Technology & Engineering categories.
Catalysis by Materials with Well-Defined Structures examines the latest developments in the use of model systems in fundamental catalytic science. A team of prominent experts provides authoritative, first-hand information, helping readers better understand heterogeneous catalysis by utilizing model catalysts based on uniformly nanostructured materials. The text addresses topics and issues related to material synthesis, characterization, catalytic reactions, surface chemistry, mechanism, and theoretical modeling, and features a comprehensive review of recent advances in catalytic studies on nanomaterials with well-defined structures, including nanoshaped metals and metal oxides, nanoclusters, and single sites in the areas of heterogeneous thermal catalysis, photocatalysis, and electrocatalysis. Users will find this book to be an invaluable, authoritative source of information for both the surface scientist and the catalysis practitioner Outlines the importance of nanomaterials and their potential as catalysts Provides detailed information on synthesis and characterization of nanomaterials with well-defined structures, relating surface activity to catalytic activity Details how to establish the structure-catalysis relationship and how to reveal the surface chemistry and surface structure of catalysts Offers examples on various in situ characterization instrumental techniques Includes in-depth theoretical modeling utilizing advanced Density Functional Theory (DFT) methods