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 H2 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/Al2 O3 , Au/TiO2 , AuZnO, and Au/ZrO2 catalysts for methanol formation under moderate reaction conditions at a pressure of 5 bar and temperatures between 220 and 240 °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.