Departmental Papers (CBE)

Document Type

Journal Article

Date of this Version

December 2004

Comments

Postprint version. Published in Applied Catalysis A: General, Volume 277, Issues 1-2, 8 December 2004, pages 129-136.
Publisher URL: http://dx.doi.org/10.1016/j.apcata.2004.09.003

Abstract

The oxidation of methane, ethane, propane, and n-butane has been studied over CeO2 and Ce0.8Sm0.2Ox (SDC) catalysts. The rates for methane and ethane were found to be indistinguishable over the two catalysts, while the rates for propane and n-butane were much higher on ceria compared to SDC. The difference between n-butane oxidation over ceria and SDC is shown to result from a low-temperature rate process on ceria that is not present on SDC. Measurements using CD4 and C4D10 show that both low- and high-temperature rates exhibit a similar kinetic-isotope effect; however, the low-temperature process is half-order in O2, while the high-temperature process is zeroth-order. Pulse studies demonstrate that oxygen from the bulk becomes accessible for reaction at approximately the same temperature as that at which the high-temperature rate process becomes important. The implications of these results for understanding the effect of doping on reactions over ceria, and for characterization of oxides using standard test reactions, are discussed.

Keywords

ceria, samaria, samaria-doped ceria (SDC), methane oxidation, ethane oxidation, propane oxidation, n-butane oxidation, kinetic-isotope effect

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Date Posted: 09 February 2006

This document has been peer reviewed.