Characterization of Ag and Ba-modified manganese oxide catalysts: unraveling the factors leading to their enhanced CH4 oxidation activity

Autor:	You-chang Xie, Xiang Wang
Rok vydání:	2001
Předmět:	chemistry.chemical_classification Reactive oxygen species X-ray photoelectron spectroscopy Chemistry education Inorganic chemistry Materials Chemistry Lattice oxygen General Chemistry Oxidation Activity Manganese oxide Catalysis
Zdroj:	New Journal of Chemistry. 25:964-969
ISSN:	1369-9261 1144-0546
DOI:	10.1039/b101116m
Popis:	Catalysts based on manganese oxide and modified with Ag (AgMn0.10) or Ba (BaMn0.10) were prepared and applied to CH4 deep oxidation. The catalysts were characterized by means of N2-BET, XRD, XPS, CH4-TPR and O2-TPD techniques. Catalytic evaluation results show that both AgMn0.10 and BaMn0.10 exhibit higher CH4 oxidation activity than the unmodified MnOx. However, comparative studies on CO oxidation reveal that only AgMn0.10 displays markedly improved activity for this reaction; the activity of BaMn0.10 remains unchanged compared to unmodified MnOx. In AgMn0.10, a large amount of more mobile and reactive oxygen species is formed, which is thought to be the main reason for its enhanced CH4 and CO oxidation activity. Whereas, in BaMn0.10, it is found that the mobility of the lattice oxygen is not increased, but somewhat decreased, thus resulting in no enhanced CO oxidation activity on this catalyst. However, the basicity of the lattice O2− is thought to be increased ia Ba addition, which is favorable for the activation and rupture of the first C–H bond in CH4, the rate-determining step for this reaction. Indeed, this modification effect of Ba is believed to be the predominant factor responsible for the enhanced CH4 oxidation activity of BaMn0.10.
Databáze:	OpenAIRE
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