Catalytic Esterification of Carbon Dioxide and Methanol for the Preparation of Dimethyl Carbonate

摘要

Dimethyl carbonate (DMC) is an important methylating agent and potential additive for clean fuel production. Several processes have been developed for the manufacture of DMC. The direct synthesis of DMC from CO_2 and methanol is especially attractive and important. In this work, the continuous synthesis of DMC from methanol and CO_2 in the region near the critical point of CO_2, with methyl iodide and potassium carbonate as the promoters, was investigated. The reactions were performed in a stainless steel autoclave with an inner volume of 500 mL equipped with a magnetic stirrer and an electric heater. The effects of the reaction temperature and pressure were determined first. It was shown that the yield of DMC increases with the increase of the reaction pressure. When the pressure approaches the critical pressure of CO_2, the optimal yield of DMC is obtained. Then the reaction characteristic was discussed from the unique characteristics of supercritical CO_2. Finally, a new process for the production of DMC has been proposed, for which water is used as an extractant for the separation of DMC from the reaction mixture.