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

Hydrogenation of carbon dioxide (CO 2 ) to methanol (MeOH) is an effective strategy for CO 2 utilization. Because of a low equilibrium conversion of CO 2 to MeOH at high temperature, development of efficient catalytic CO 2 hydrogenation processes that operate under low reaction temperature is of extreme importance. Herein, we report that TiO 2 -supported Re (Re(1)/TiO 2; Re = 1 wt %) promotes the selective hydrogenation of CO 2 to MeOH (total TON based on Re = 44, MeOH selectivity = 82%) under mild conditions ( p CO2 = 1 MPa; p H2 = 5 MPa; T = 150 °C). Both in terms of TON and methanol selectivity, the performance of Re(1)/TiO 2 is superior to that of TiO 2 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.