Evidence for oxidation of ceria by CO2

The oxidation and reduction of Pd/ceria and Pd/zirconia catalysts were inve stigated using pulse-reactor studies in which products were monitored follo wing step changes in the reactant composition. The results demonstrate that both ceria and zirconia can be partially reduced by CO and partially reoxi dized by CO2. Steady-state rates for methane reforming by CO2 were also mea sured on Pd/ceria, Pd/zirconia, and Pd/silica. The Pd/ceria catalyst was sl ightly more active than Pd/zirconia and similar to 10(4) times as active as Pd/silica. The high activities of Pd/ceria and Pd/zirconia are explained a s resulting from oxidation and reduction of the supports. (C) 2000 Academic Press.