Direct Synthesis of Dimethylcarbonate from CO_2 and methanol with thermal driven loop reactor

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Dimethyl carbonate (DMC) is a high-value added material because its application is quite wide such as an intermediate of polymer, fuel additive, and so on. A green synthesis of DMC is direct production from CO_2 and methanol. For the reaction, a catalyst is required to proceed effectively and ZrO_2 catalysts have been found to be suitable. The byproduct of the reaction is water and the water makes the DMC yield lower because of chemical equilibrium. In order to enhance the DMC yield, removal of water from the reaction, system is strongly demanded.In this study, we planed to develop a new synthesis process of DMC from CO_2 and methanol by a thermal driven loop reactor. The thermal driven loop reactor has a heating part for the reaction and a cooling pert for the elimination of water. The employed catalyst and the dehydration agent were ZrO_2 and molecular sieve 3 A, respectively. The optimization of the reaction condition was explored through the investigation of phase equilibria and th … More e reaction behavior. Especially, the effect of the amount of the dehydration agent was evaluated. Based on the experimental studies, the model development was performed and resulted in clarification of a controlling factor of the process.First of all, we evaluated the capability of dehydration agent in high pressure reaction media for methanol-water system. As a result, the dehydration agent worked well in the thermal driven loop reactor (temperature of the heating pert : 150-160 ℃, temperature of the cooling pert : 60 ℃). Next, the phase equilibria of CO_2-methanol-water-DMC system was calculated to explore the single phase region, by a model that was created from the basis of the literature. At the decided reaction condition from the calculation (the reactor : 170℃, the dehydration pert : 25℃, pressure : 15MPa), we performed the DMC synthesis by the thermal driven loop reactor. The DMC yield was finally attained 15 mol% (on the basis of the loaded amount of methanol), whereas the DMC yield in a batch reactor at the same reaction condition was merely 1 mol%. We developed a kinetic model for the DMC synthesis by the thermal driven loop reactor to know the controlling factor of the process. Then the model tells us that the flow rate of the reaction fluid in the loop reactor was controlling factor and that the modification of the dehydration pert must be needed to improve the performance of the loop reactor. Less