TOTAL ETHANE OXIDATION OVER PD ALPHA-AL2O3 - THE PALLADIUM OXIDATION-STATE UNDER REACTION CONDITIONS/

The total oxidation of ethane was studied over Pd/alpha-Al2O3 catalyst s in an oxygen rich atmosphere. After palladium reduction by hydrogen treatment at 573 K it was found that catalysts became more active with time on stream. The increase in activity is a consequence of bulk pal ladium oxide formation. The extent of palladium oxidation at the stead y state was determined by oxygen uptake measurements before and after the reaction at 573 K and by hydrogen titration at 323 K after the rea ction. A previous oxidation or a high temperature treatment of the rea ction mixture did not affect the level of activity and a time dependen t activation process was not observed. The catalytic activity of palla dium does not depend on the initial metal dispersion. Moreover, the ra te of reaction was found to depend on the total amount of palladium. T his result suggests that under reaction conditions all palladium atoms become active for C2H6 oxidation.