Mechanistic Study of the Hydrogenation of Carbon Dioxide to Methanol over Supported Rhenium and Copper-Zinc Catalysts

Article abstract of DOI:10.1246/bcsj.64.3432

The reaction of a mixture containing (13)CO, CO2, and H2 was carried out in order to elucidate the reaction mechanisms of carbon dioxide hydrogenation to methanol over supported Re catalysts as well as Cu-Zn oxide catalysts.The reactions of formic acid and formaldehyde with hydrogen were also examined.From the incorporation of (13)C in the product methanol, it could be distinguished whether the carbon dioxide hydrogenation to methanol proceeds through formation and successive hydrogenation of CO or by direct hydrogenation of CO2.Methanol is formed almost exclusively by direct hydrogenation of CO2 over CuO-ZnO based catalysts.However, the two reaction routes operate over Re/ZrO2 and Re/CeO2, the contribution of route via CO being higher over Re/ZrO2 than over Re/CeO2.The reactions of formic acid and formaldehyde with hydrogen suggest that the surface formate and the absorbed formaldehyde are involved in the methanol formation, and that the conversion of the formate to the adsorbed formaldehyde is a key step.