The influence of the support on the activity and selectivity of Pd in CO hydrogenation

Catalytic hydrogenation of carbon monoxide was studied over Pd supported on Al2O3, SiO2, TiO2, and ZrO2. Both the activity and the selectivity of the catalysts were strongly affected by the nature of the support. As a major product, Pd/Al2O3 produces dimethyl ether, Pd/SiO2 favors methanol formation, Pd/TiO2 produces CH4, and Pd/ZrO2 yields methanol. Higher CO conversions over Pd/ZrO2 and Pd/TiO2 were ascribed to the presence of cationic palladium species formed through the metal-support interaction. Significant dimethyl ether formation over Pd/Al2O3 was attributed to the acidity of the support metal oxide. The catalytic natures of Pd catalysts were discussed based on the results of catalyst characterization by XPS, TEM, and temperature-programmed reduction and desorption. (C) 2001 Elsevier Science B.V. All rights reserved.