Comparative study between gas phase and liquid phase for the production of DMC from methanol and CO2

Direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide over Co_1.5PW₁₂O₄₀ in liquid and in gas phase is investigated. The synthesized catalyst has been characterized by means of FTIR and XRD. Liquid phase experiment results showed that high pressures are favorable for the synthesis of DMC. However, DMC formation is limited by the reaction with co-produced water. DMC selectivity is more strongly dependent on the temperature than on the pressure of CO₂. As for the reactions in gas phase, it has been found that both CH3OH conversion and DMC selectivity decreased with increasing temperature, owing to the decomposition of DMC at high temperatures. High temperatures and more amount of Co_1.5PW₁₂O₄₀ catalyst favor the formation of dimethoxymethane (DMM) and methyl formate (MF).