The activity of ceria-zirconia supported palladium catalysts for methane combustion has been found to be strongly dependent on the oxygen content of the PdO catalyst particles. Reaction mixture pulses of 1% methane, 4% oxygen and helium balance were injected over partially reduced catalysts obtained by chemical reduction with methane, and over completely reduced catalysts produced by thermal decomposition of the PdO phase. Catalyst activity was observed

The time constant for equilibration of water adsorption/desorption during methane combustion over zirconia supported palladium catalyst was qualitatively studied at different reaction temperatures under both pulsed and continuous flow experiments. Water inhibition of methane oxidation was found to depend strongly on the time constant for equilibration of the adsorption/desorption of water, which, in turn, is a strong function of temperature. In pulsed

Measurements of zirconia band gap under diffrent crystalline structures.

The effect of the support (gamma -alumina and zirconia) and of the presence of water on the catalytic activity of palladium particles was investigated both on oxidized and reduced states using temperature programmed reaction (TPR). The support was found to influence the onset and the rate of the reoxidation process. The particle size of the palladium phase, however, strongly influenced the reduction temperature and the activity decay and recovery

We have examined the adsorption of CO and NO on powder Pd/Al2O3, Pd-Ce/Al2O3 and CeO2/Al2O3 catalysts, using temperature-programmed desorption (TPD). For CO adsorption on oxidized and pre-reduced Pd-Ce/Al2O3 TPD profiles are identical to those observed for Pd/Al2O3, suggesting that interactions between ceria and Pd have a negligible effect on the adsorption properties of CO. It does, however, affect the oxidation state of the palladium particles.