Hydrogenation of CO2 to Methanol at Atmospheric Pressure over Cu/ZnO Catalysts: Influence of the Calcination, Reduction, and Metal Loading

Cu/ZnO catalysts have been widely studied for the hydrogenation of carbon dioxide to methanol at atmospheric pressure. In the work described here, several interesting issues are highlighted that have rarely been considered previously. An extensive study of the influence of the calcination and reduction temperatures and the metal loading was carried out. The best conditions found for catalyst preparation were calcination at 350 degrees C and reduction at 200 degrees C. The role of the different oxidation states of copper (Cu2+, Cu1+, and Cu-0) was proven in the methane and methanol formation. CuZn alloy formation was observed when a reduction temperature of 400 degrees C was used. The use of this alloy led to higher methanol selectivity at higher temperatures (>200 degrees C). Finally, the metal loading study confirm the dual-site nature of the methanol synthesis mechanism.