Low-Temperature Hydrogenation of CO2 to Methanol over Heterogeneous TiO2-Supported Re Catalysts

Hydrogenation of carbon dioxide (CO2) to methanol (MeOH) is an effective strategy for CO2 utilization. Because of a low equilibrium conversion of CO2 to MeOH at high temperature, development of efficient catalytic CO2 hydrogenation processes that operate under low reaction temperature is of extreme importance. Herein, we report that TiO2 -supported Re (Re(1)/TiO2 ; Re = 1 wt %) promotes the selective hydrogenation of CO2 to MeOH (total TON based on Re = 44, MeOH selectivity = 82%) under mild conditions (p(CO2)= 1 MPa; P-H2 = 5 MPa; T = 150 degrees C). Both in terms of TON and methanol selectivity, the performance of Re(1)/TiO2 is superior to that of TiO2 catalysts loaded with other metals and to Re catalysts on other support materials. In addition, our investigations include the reaction mechanism and structure-activity relationship for the catalytic system used in this study, suggesting that relatively reduced Re species (oxidation state: 0-4) of subnanometer size serve as the catalytically active site for the formation of MeOH.