Effect of reduction temperature on structural properties and CO/CO2 hydrogenation characteristics of a Pd-CeO2 catalyst

The effect of the temperature of reduction on the activity and selectivity of a Pd-CeO2 catalyst was studied for the hydrogenation of CO and CO2. A dr astic decrease in the overall conversions of carbon oxides and a significan t modification in the product selectivity were observed when the catalyst w as reduced at 773 K. The main reason for the decrease in the overall cataly tic activity was the occurrence of severe sintering of palladium particles during high temperature reduction, evidenced by extended X-ray absorption f ine structure (EXAFS) and X-ray diffraction (XRD) measurements. The remarka ble changes in the selectivities of the products were explained by the deco ration phenomenon of palladium surface by reduced ceria species due to the phase change between CeO2 and Ce2O3 upon reduction at 773 K. (C) 2001 Elsev ier Science B.V. All rights reserved.