Catalytic Conversion Of Methane To Partially Oxidized Products Over Copper Exchanged Zeolites
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Catalytic Conversion Of Methane To Partially Oxidized Products Over Copper Exchanged Zeolites
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Author : Kimberly Tam Dinh
language : en
Publisher:
Release Date : 2020
Catalytic Conversion Of Methane To Partially Oxidized Products Over Copper Exchanged Zeolites written by Kimberly Tam Dinh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
The selective conversion of methane to liquid oxygenated compounds is a grand challenge in catalysis. Although natural gas can be processed industrially in large-scale facilities, new catalytic processes are required that economically directly convert methane to liquid products in small-scale units to exploit highly abundant but difficult-to-access gas reserves. Our group recently reported the first instance of a continuous, gas phase catalytic process for the direct conversion of methane to methanol using copper-exchanged zeolites by feeding only methane, water, and oxygen at 473 K. While this continuous system is an attractive route for the mild conversion of methane to value-added products, fundamental understanding of the reaction pathway and active site is necessary to engineer improved catalysts and an improved process. Thus, my thesis has investigated the fundamental kinetics and active site requirements for continuous partial methane oxidation and using this knowledge to design an improved process. First, a reaction pathway and a [Cu-O-Cu]2+ motif as the active site were identified for the selective catalytic conversion of methane to methanol. Kinetic analysis on copper-exchanged SSZ-13 zeolites across a range of Cu loadings and Al spatial distributions revealed the reaction pathway is initiated by rate-limiting C-H bond scission of methane. Water is kinetically inconsequential, but required for methanol desorption. Carbon dioxide is generated from the sequential over oxidation of partially oxidized intermediates and downstream methanol oxidation. Selective partial oxidation was achieved with catalyst samples of high Al content and moderate Cu content (Cu/cage
Methane Oxidation Over Dual Redox Catalysts
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Author :
language : en
Publisher:
Release Date : 1992
Methane Oxidation Over Dual Redox Catalysts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with categories.
Catalytic oxidation of methane to partial oxidation products, primarily formaldehyde and C[sub 2] hydrocarbons, was found to be directed by the catalyst used. In this project, it was discovered that a moderate oxidative coupling catalyst for C[sub 2] hydrocarbons, zinc oxide, is modified by addition of small amounts of Cu and Fe dopants to yield fair yields of formaldehyde. A similar effect was observed with Cu/Sn/ZnO catalysts, and the presence of a redox Lewis acid, Fe[sup III] or Sn[sup IV], was found to be essential for the selectivity switch from C[sub 2] coupling products to formaldehyde. The principle of double doping with an oxygen activator (Cu) and the redox Lewis acid (Fe, Sn) was pursued further by synthesizing and testing the CuFe-ZSM-5 zeolite catalyst. The Cu[sup II](ion exchanged) Fe[sup III](framework)-ZSM-5 also displayed activity for formaldehyde synthesis, with space time yields exceeding 100 g/h-kg catalyst. However, the selectivity was low and earlier claims in the literature of selective oxidation of methane to methanol over CuFe-ZSM-5 were not reproduced. A new active and selective catalytic system (M=Sb, Bi, Sn)/SrO/La[sub 2]O[sub 3] has been discovered for potentially commercially attractive process for the conversion of methane to C[sub 2] hydrocarbons, (ii) a new principle has been demonstrated for selectivity switching from C[sub 2] hydrocarbon products to formaldehyde in methane oxidations over Cu, Fe-doped zinc oxide and ZSM-5, and (iii) a new approach has been initiated for using ultrafine metal dispersions for low temperature activation of methane for selective conversions. Item (iii) continues being supported by AMOCO while further developments related to items (i) and (ii) are the objective of our continued effort under the METC-AMOCO proposed joint program.
Methane Oxidation Over Dual Redox Catalysts Final Report
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Author :
language : en
Publisher:
Release Date : 1992
Methane Oxidation Over Dual Redox Catalysts Final Report written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with categories.
Catalytic oxidation of methane to partial oxidation products, primarily formaldehyde and C2 hydrocarbons, was found to be directed by the catalyst used. In this project, it was discovered that a moderate oxidative coupling catalyst for C2 hydrocarbons, zinc oxide, is modified by addition of small amounts of Cu and Fe dopants to yield fair yields of formaldehyde. A similar effect was observed with Cu/Sn/ZnO catalysts, and the presence of a redox Lewis acid, Fe{sup III} or Sn{sup IV}, was found to be essential for the selectivity switch from C2 coupling products to formaldehyde. The principle of double doping with an oxygen activator (Cu) and the redox Lewis acid (Fe, Sn) was pursued further by synthesizing and testing the CuFe-ZSM-5 zeolite catalyst. The Cu{sup II}(ion exchanged) Fe{sup III}(framework)-ZSM-5 also displayed activity for formaldehyde synthesis, with space time yields exceeding 100 g/h-kg catalyst. However, the selectivity was low and earlier claims in the literature of selective oxidation of methane to methanol over CuFe-ZSM-5 were not reproduced. A new active and selective catalytic system (M=Sb, Bi, Sn)/SrO/La2O3 has been discovered for potentially commercially attractive process for the conversion of methane to C2 hydrocarbons, (ii) a new principle has been demonstrated for selectivity switching from C2 hydrocarbon products to formaldehyde in methane oxidations over Cu, Fe-doped zinc oxide and ZSM-5, and (iii) a new approach has been initiated for using ultrafine metal dispersions for low temperature activation of methane for selective conversions. Item (iii) continues being supported by AMOCO while further developments related to items (i) and (ii) are the objective of our continued effort under the METC-AMOCO proposed joint program.
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.
Theoretical Insights Into The Selective Oxidation Of Methane To Methanol In Copper Exchanged Mordenite
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Author :
language : en
Publisher:
Release Date : 2016
Theoretical Insights Into The Selective Oxidation Of Methane To Methanol In Copper Exchanged Mordenite written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Selective oxidation of methane to methanol is one of the most difficult chemical processes to perform. A potential group of catalysts to achieve CH4 partial oxidation are Cu-exchanged zeolites mimicking the active structure of the enzyme methane monooxygenase. However, the details of this conversion, including the structure of the active site, are still under debate. In this contribution, periodic density functional theory (DFT) methods were employed to explore the molecular features of the selective oxidation of methane to methanol catalyzed by Cu-exchanged mordenite (Cu-MOR). We focused on two types of previously suggested active species, CuOCu and CuOOCu. Our calculations indicate that the formation of CuOCu is more feasible than that of CuOOCu. In addition, a much lower C-H dissociation barrier is located on the former active site, indicating that C-H bond activation is easily achieved with CuOCu. We calculated the energy barriers of all elementary steps for the entire process, including catalyst activation, CH4 activation, and CH3OH desorption. Finally, our calculations are in agreement with experimental observations and present the first theoretical study examining the entire process of selective oxidation of methane to methanol.
Natural Gas Conversion Viii
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Author : Fabio Bellot Noronha
language : en
Publisher: Elsevier
Release Date : 2011-09-22
Natural Gas Conversion Viii written by Fabio Bellot Noronha and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-09-22 with Technology & Engineering categories.
This volume contains peer-reviewed manuscripts describing the scientific and technological advances presented at the 8th Natural gas Conversion Symposium held in Natal-Brazil, May 27-31, 2007. This symposium continues the tradition of excellence and the status as the premier technical meeting in this area established by previous meetings. The manuscripts have been divided into eight different topics, Industrial Processes, Economics, Technology Demonstration and Commercial Activities;, Production of Hydrogen from Methane, Methanol, and Other Sources; Production of Synthesis; Fischer-Tropsch Synthesis of Hydrocarbons; From Synthesis Gas to; Catalytic Combustion; From Natural Gas to Chemicals; Light Hydrocarbons; and Production and Conversion. These are the most interesting subjects in the utilization of natural gas with recent scientific innovation and technological advances. The book is of interest to all students and researchers active in utilization of natural gas. * Research comes from the most important industries and research centres in the field * Features new studies from all around the world * Important for consulting and updating research and development data
Methane Conversion By Oxidative Processes
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Author : Eduardo E. Wolf
language : en
Publisher: Springer
Release Date : 1992
Methane Conversion By Oxidative Processes written by Eduardo E. Wolf and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Science 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.
Catalysis And The Mechanism Of Methane Conversion To Chemicals
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Author : Toshihide Baba
language : en
Publisher: Springer Nature
Release Date : 2020-04-18
Catalysis And The Mechanism Of Methane Conversion To Chemicals written by Toshihide Baba and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-04-18 with Science categories.
This book introduces various types of reactions to produce chemicals by the direct conversion of methane from the point of view of mechanistic and functional aspects. The chemicals produced from methane are aliphatic and aromatic hydrocarbons such as propylene and benzene, and methanol. These chemicals are created by using homogeneous catalysts, heterogeneous catalysts such as zeolites, and biocatalysts such as enzymes. Various examples of methane conversion reactions that are discussed have been chosen to illustrate how heterogeneous and homogenous catalysts and biocatalysts and/or their reaction environments control the formation of highly energetic species from methane contributing to C-C and C-O bond formation.
The Catalytic Conversion Of Methane By Partial Oxidation
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Author : Woodhouse Jeremy Robert
language : en
Publisher:
Release Date : 1989
The Catalytic Conversion Of Methane By Partial Oxidation written by Woodhouse Jeremy Robert and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Catalysis categories.
Methane Partial Oxidation Over Phthalocyanine Catalyst
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Author : Yuan Zhu
language : en
Publisher:
Release Date : 2013
Methane Partial Oxidation Over Phthalocyanine Catalyst written by Yuan Zhu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
The partial oxidation reaction of methane over a zeolite-supported ruthenium phthalocyanine catalyst is studied in a packed bed reactor. The investigation of such reaction is desirable because partial oxidation of methane yields a synthesis gas that can be upgraded to liquid chemicals and fuels. Reactants of this study are He-diluted CH4 and O2. The effluent includes unreacted CH4 and O2, He, CO, CO2, H2, and H2O vapor. Thermal conductivity gas chromatography is applied to identify the mole fractions of reactants and products. System pressure is maintained at 50 psig. Experiments are run at 250, 275, 300, 325, 350, and 375°C. For each temperature, the feed molar ratio of CH4/O2 is varied from 0.5 to 5.0. Although reaction temperature is more than 200°C lower than that of common catalytic methane partial oxidation, conversion of methane is obvious. Product analysis indicates that the highest conversion is 80.4% at 375°C, CH4/O2=0.5. Conversion of methane increases with increasing temperature, but it decreases with increasing molar ratio CH4/O2. Selectivities of both H2 and CO increase with the increasing temperature or molar ratio CH4/O2. But selectivity of CO2 decreases with the increasing temperature or molar ratio CH4/O2. Based on a differential packed bed reactor model, the global rate of CH4 reaction shows first order dependencies on each of O2 and CH4. The overall reaction rate is a second-order reaction. The reaction rate constant k for each temperature was also determined. An Arrhenius plot of the global rate constants suggest that the reaction is limited by reaction kinetics between 250-300°C, and limited by mass transfer between 300-375°C. Equilibrium calculations are also made for all cases in this study. The result shows that products selectivities of equilibrium calculation are significantly different from that of catalytic reactions, which emphasizes the effective catalytic actions of the zeolite-supported ruthenium phthalocyanine.