Synthesis of dimethyl carbonate from methanol and carbon dioxide: Circumventing thermodynamic limitations

The synthesis of dimethyl carbonate from methanol and CO₂ catalyzed by ZrO₂ doped with KCl was investigated using chemical traps for water to circumvent thermodynamic limitations. The reaction, promoted by magnesium, occurred via the formation of carbonated magnesium methoxide (CMM) which adsorbed on the surface of ZrO₂. The surface migration of the oxygen atom of ZrO₂ to the surface methoxy groups of CMM resulted in the formation of dimethyl carbonate. The resulting MgO then reacted with methanol forming water and regenerating magnesium methoxide. The water formed reacted with the dehydrating agent, thus shifting the equilibrium toward a higher yield of DMC. The yield of 7.2 mol % DMC and 13.6 mol % conversion of methanol was obtained when methanol reacted with CO₂ at 150 °C and 9.5 MPa for 8 h. The plausible reaction pathway is described.