Isotopic studies of Sn-Cr binary oxide catalysts for methane total oxidation

A series of Sn-Cr binary oxide catalysts were prepared by a co-current co-precipitation method and tested for methane total oxidation. The binary oxide catalysts have much higher surface areas and catalytic activities for methane oxidation than pure SnO2. CrOx/SnO2 with a Cr/Sn atomic ratio of 3:7 d...

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Bibliographic Details
Published in:Catalysis letters 2003-02, Vol.85 (3-4), p.205-211
Main Authors: ZHU, Yue-Xiang, MURWANI, Irmina K, ZHOU, Chang-Jun, KEMNITZ, Erhard, XIE, You-Chang
Format: Article
Language:English
Subjects:
Catalysis
Catalysts
Catalysts: preparations and properties
Catalytic oxidation
Chemistry
Chromium
Exact sciences and technology
Exchanging
General and physical chemistry
Methane
Oxidation
Oxygen
Reaction mechanisms
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Tin dioxide
Valence
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Summary:A series of Sn-Cr binary oxide catalysts were prepared by a co-current co-precipitation method and tested for methane total oxidation. The binary oxide catalysts have much higher surface areas and catalytic activities for methane oxidation than pure SnO2. CrOx/SnO2 with a Cr/Sn atomic ratio of 3:7 displays the highest activity. Selected samples were subjected to temperature-programmed 18O isotope-exchange measurements. Both complete and partial heteromolecular 18O isotope exchange, as well as oxygen release, was observed for all catalysts. Reaction between CH4 and 18O2 under static conditions was performed to investigate the reaction mechanism and it was found that the total oxidation of methane over Sn-Cr binary oxide catalysts occurs via a redox cycle with the chromium ion in a high oxidation state as the active center. Oxygen mobility of the catalyst plays an important role in the total oxidation of methane, but too high a mobility leads to very high oxygen release and a reduction of the surface reoxidability. This causes a decrease in the catalytic oxidation activity.
ISSN:1011-372X
1572-879X
DOI:10.1023/A:1022197830984