Mononuclear Re sites on In2O3 catalyst for highly efficient CO2 hydrogenation to methanol

Abstract

Catalytic hydrogenation of CO2 to methanol utilizing H2 derived from renewable energy represents one of the most prospective strategies for the sustainable recycle of carbon. Accordingly, the design and preparation of high-performance catalysts for methanol production has received broad attention. Herein, In2O3 supported mononuclear Re is reported to be an efficient catalyst for methanol production which exhibits methanol selectivity of up to 80% at CO2 conversion of 11.5%, providing a methanol STY of 758 mg·h−1·gcat−1 under 5 MPa and 300 °C, more than twice as that for pristine In2O3 (376 mg·h−1·gcat−1). The apparent reaction orders of CO2 and H2 were determined to be around 0 and 0.6 respectively, suggesting the activation of H2 is more crucial compared with CO2. In-depth characterizations reveal that the remarkably improved performance originates from the mononuclear Ren+ sites strongly interacting with In2O3, which significantly enhance the ability of H2 dissociation. Combined experimental and theoretical studies proved the feasibility of formate pathway over In2O3 supported mononuclear Re catalyst. The results of DFT calculations suggest that mononuclear Re site on In2O3(111) model plays a vital role on heterolytic H2 dissociation and intermediates transformation, boosting the formation of HCOO* and lowering the energy barriers of rate-determining step for methanol formation.