Continuous heterogeneous hydrogenation of CO2-derived dimethyl carbonate to methanol over a Cu-based catalyst

Abstract

Catalytic mild hydrogenation of carbonates synthesized from the CO₂ captured by alcohols is of significant interest both conceptually and practically, which provides alternative approaches to the indirect hydrogenation of CO₂ to methanol. However, the catalytic efficiency of the process of dimethyl carbonate (DMC) hydrogenation still remains unsatisfactory. Unprecedented gas–solid phase fix-bed catalyzed hydrogenation of DMC to methanol has been made. Herein, we address this issue with facile Cu/SiO₂ catalysts, reaching complete conversion and highly selective formation of methanol (up to 80% yield) under mild conditions (503 K, 2.5 MPa), which is the highest yield that has been reported. Characterization results indicate that the copper dispersion and the synergetic effect between balanced Cu⁰ and Cu⁺ sites are considered to play critical role in attaining high yield of methanol. The optimized Cu/SiO₂ catalyst displayed excellent catalytic performance in the hydrogenation of diethyl carbonate (DEC) and di-n-propyl carbonate (DPC) as well, presenting a broad substrate scope. Moreover, the comparative catalytic activity (∼76% methanol yield) in the hydrogenation of DMC under solvent-free conditions shows promise for its scalable application in industry.