Direct synthesis of dimethyl carbonate from CO 2 and methanol by supported bimetallic Cu–Ni/ZIF-8 MOF catalysts

Supported bimetallic Cu–Ni/ZIF-8 metal oxide framework (MOF) catalysts were synthesized for the production of dimethyl carbonate (DMC) from CO2 and methanol. The catalytic support material, zeolitic imidazolate framework-8 (ZIF-8), was prepared by solvothermal method using methanol (MeOH) as a solvent and then loaded with bimetallic Cu–Ni catalyst (1:1 by weight) via an incipient wetness impregnation. The support material and synthesized catalysts were first characterized using powder XRD, TGA, FT-IR, FE-SEM, TEM, BET and ICP–OES analysis. Then, the ZIF-8 supported bimetallic catalysts were tested for catalytic activity in the direct synthesis of DMC from CO2 and MeOH. Various parameters—metal loading content, reaction temperature, weight of catalyst loading and reaction time—and their effects were investigated. The highest DMC yield (6.39%) and the highest MeOH conversion (12.79%) were achieved at 20 bar of CO2, 110 °C and 12 h using 0.7 g of 5%Cu–Ni/ZIF-8 catalyst. Under the optimized conditions, the catalyst was able to retain its catalytic performance up to 4 regeneration cycles. These results indicate that supported bimetallic Cu–Ni/ZIF-8 catalysts have a high potential for synthesis of DMC.