Methane Oxidation Over Dual Redox Catalysts

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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 Oxidation Over Dual Redox Catalysts

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Author :
language : en
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Release Date : 1989

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 1989 with categories.

The objective of this research is to develop the scientific background for direct catalytic oxidation of methane over oxides that are doubly doped with transition metal ions. The desired process aims at employing of a double redox mechanism, where one redox couple is utilized for activation of oxygen and another for the conversion of CH3 radicals to carbocations via electron transfer reaction. The latter species can react with surface OH− groups to form methanol or formaldehyde. To establish the foundations for such a process, two groups of the catalysts, one containing dispersed redox centers (Cu{sup I}/Fe{sup III}/ZnO and Cu{sup I}/Sn{sup IV}/ZnO) and a second of delafossite-type oxides containing concentrated redox centers (CuFeO2, CuCoO2) were synthesized and chemically analyzed for composition. For the sake of comparison, undoped ZnO treated in the same way as doped zinc oxide catalysts was also prepared. The samples were characterized by X-ray diffraction, BET surface area measurements and preliminarily by scanning electron microscopy. A catalytic testing unit and reactor to study the title reaction were designed and constructed.

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report April June 1989

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language : en
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Release Date : 1989

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report April June 1989 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with categories.

The objective of this research is to develop the scientific background for direct catalytic oxidation of methane over oxides that are doubly doped with transition metal ions. The desired process aims at employing of a double redox mechanism, where one redox couple is utilized for activation of oxygen and another for the conversion of CH3 radicals to carbocations via electron transfer reaction. The latter species can react with surface OH− groups to form methanol or formaldehyde. To establish the foundations for such a process, two groups of the catalysts, one containing dispersed redox centers (Cu{sup I}/Fe{sup III}/ZnO and Cu{sup I}/Sn{sup IV}/ZnO) and a second of delafossite-type oxides containing concentrated redox centers (CuFeO2, CuCoO2) were synthesized and chemically analyzed for composition. For the sake of comparison, undoped ZnO treated in the same way as doped zinc oxide catalysts was also prepared. The samples were characterized by X-ray diffraction, BET surface area measurements and preliminarily by scanning electron microscopy. A catalytic testing unit and reactor to study the title reaction were designed and constructed.

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report July September 1989

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language : en
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Release Date : 1989

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report July September 1989 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with categories.

The objective of this research is to develop approaches to direct catalytic oxidation of methane over oxides that are doubly doped with transition metal ions. The desired process aims at employing a double redox mechanism, where one redox couple is utilized for activation of oxygen and another for the trapping of CH3 radicals. The methyl radicals can either recombine, giving C2 hydrocarbons, or be converted, via electron transfer reaction, to carbocations. The latter species can react with surface OH− groups to form methanol or formaldehyde. To choose from several possible catalytic systems, this research initially involved the characterization of the micromorphology and crystalline dimensions of zinc oxide catalysts doped with Cu, Fe, and Sn by scanning electron microscopy. In addition, the determination of surface composition and oxidation states by X-ray photoelectron spectroscopy was carried out. A newly constructed high temperature catalytic testing system has been calibrated (flow meters and temperature controllers), tested for possible gas leaks and integrated with a gas chromatographic analytical unit. A preliminary catalytic test study over a Cu/Fe/ZnO sample was performed. The following products of the methane coupling reaction was found: C2H6, C2H4 and H2O together with CO2. The maximum space time yield of 14 mmol C2 hydrocarbons/g cat/h was obtained at 848°C.

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report January 1 March 31 1989

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language : en
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Release Date : 1989

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report January 1 March 31 1989 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with categories.

Review and analysis of the literature data on electron transfer itself and electron transfer oxidation of alkyl radicals was done in order to understand the mechanism by which methyl radical can be oxidized to CH3 and further substituted by OH− to form methanol. This allowed to compare and classify the various possible reaction patterns, understand the mechanism and circumstances of operation of each of them and select those which can be involved in oxidation of methyl radical. As a result an approach that is complementary to catalytic test studies was proposed. It consists of investigation of a set of partial reactions which reproduce a whole catalytic cycle in order to prove the reaction mechanism. Synthesis of new oxide catalysts of the delafossite type, containing concentrated double redox sites, were designed. Synthesis of hydrozincite as a starting material for the preparation of doubly doped zinc oxide was performed.

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report October December 1991

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language : en
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Release Date : 1992

Methane Oxidation Over Dual Redox Catalysts Quarterly Technical Progress Report October December 1991 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.

The effect of doping lanthana-based catalysts with antimony and bismuth on the catalytic behavior toward the selective oxidation of methane has been studied. New catalytic results have been obtained upon doping the Sr/La2O3 catalyst, obtained from AMOCO Oil Co., with the acidic Sb and Fe dopants. Both activity and selectivity of the original Sr/La2O3 catalyst can be modified by introducing small amounts of either dopant. Iron doping lowered selectivity to C2 products whereas antimony increased the selectivity while decreasing the reaction temperature by 100°C.

Twee Publicaties Uitgevaardigd Door Het Bestuur Der Landschap Drenthe 29 Augustus 1806

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language : en
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Release Date : 1806

Twee Publicaties Uitgevaardigd Door Het Bestuur Der Landschap Drenthe 29 Augustus 1806 written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1806 with categories.

Scientific And Technical Aerospace Reports

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language : en
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Release Date : 1995

Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.

Energy Research Abstracts

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language : en
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Release Date : 1993

Energy Research Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with Power resources categories.

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language : en
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Release Date : 1978

written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1978 with categories.