EFFECTS OF CATALYSTS ON DIMETHYL CARBONATE SYNTHESIS FROM METHANOL AND SUPERCRITICAL CARBON DIOXIDE

摘要

The synthesis of dimethyl carbonate(DMC) from methanol and supercritical carbon dioxide over various basic catalysts was studied in the batch reactor. Compounds of group I elements(Li, Na and K) were used as basic catalysts. The promoter and the dehydrating agent were also used to enhance the yield of DMC. By-products such as dimethyl ether(DME) and C_1-C_2 hydrocarbons as well as DMC were formed in this reaction system. The yield of DMC with different alkali metal catalysts ranked in the following order: K > Na > Li. CO_3~(2-) containing catalysts were more effective than OH~- containing catalysts on the DMC synthesis. The reaction mechanism of DMC synthesis from methanol and supercritical carbon dioxide was proposed. The maximum DMC yield reached up to 12 mole% in the presence of K_2CO_3(catalyst), CH_3I (promoter) and 2,2-dimethoxypropane (dehydrating agent) at 130 - 140℃, 200bar.