CO2 Hydrogenation to Methanol on Supported Au Catalysts under Moderate Reaction Conditions: Support and Particle Size Effects

The potential of metal oxide supported Au catalysts for the formation of methanol from CO2 and H-2 under conditions favorable for decentralized and local conversion, which could be concepts for chemical energy storage, was investigated. Significant differences in the catalytic activity and selectivity of Au/Al2O3, Au/TiO2, AuZnO, and Au/ZrO2 catalysts for methanol formation under moderate reaction conditions at a pressure of 5bar and temperatures between 220 and 240 degrees C demonstrate pronounced support effects. A high selectivity (>50%) for methanol formation was obtained only for Au/ZnO. Furthermore, measurements on Au/ZnO samples with different Au particle sizes reveal distinct Au particle size effects: although the activity increases strongly with the decreasing particle size, the selectivity decreases. The consequences of these findings for the reaction mechanism and for the potential of Au/ZnO catalysts for chemical energy storage and a green methanol technology are discussed.