Combustion activity of Ag/CeO2 composite catalyst

Oxidation of methane and carbon monoxide was carried out on silver/ceria co mposite oxide prepared by co-precipitation, and the behavior of the lattice oxygen of silver was investigated. In the high temperature oxidation of me thane, silver(I) oxide decomposed and aggregated to large particles of meta llic silver and rapidly deactivated. On the other hand, silver retained hig h activity during the low temperature oxidation of carbon monoxide. It was found, however, that ceria accelerated the desorption of the lattice oxygen of silver, which was assumed to be related to the well known oxygen storag e function of ceria. Although silver tends to be converted more easily to m etallic state in the presence of ceria, the function of ceria of sustaining the dispersed state of silver will help to maintain the high activity of t he latter in the oxidation of carbon monoxide. (C) 2000 Elsevier Science B. V. All rights reserved.