Dimethyl carbonate synthesis by electrolytic carbonylation of methanol in the gas phase

The synthesis of dimethyl carbonate by electrolytic carbonylation of CH3OH was performed using a PdCl2-added graphite anode in a gas mixture of CH3OH and CO at < 101 kPa and ambient temperature. The formation of dimethyl carbonate was initiated at an applied voltage across the cell greater than 0.3 V when O2 (85 kPa) was passed in the cathode compartment. Dimethoxy methane and methyl formate were formed at >0.5 V. Decrease in the reaction temperature accelerated the rate of dimethyl carbonate formation. The results of the electrolysis of CH3OH alone suggested that dimethoxy methane and methyl formate in the presence of CO were formed directly from CH3OH by electrolysis. The results of each experiment of CH3OH, dimethyl carbonate, methyl formate or CO alone showed that most of the CO2 formed was ascribed to the electrolysis of CO. The active site for the formations of dimethyl carbonate and dimethoxy methane (and methyl formate) was suggested to be Pd2+. On the basis of kinetic studies for the formation of each product in detail, tentative reaction schemes have been proposed.