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

碳酸二甲酯（DMC）作为聚合物中间体、燃料添加剂等用途广泛，是一种高附加值材料。以CO_2和甲醇为原料直接生产DMC是一种绿色合成方法。该反应需要催化剂才能有效进行，ZrO_2催化剂是比较合适的。反应的副产物是水，由于化学平衡，水使DMC产率降低。为了提高DMC产率，强烈要求从反应体系中去除水。在本研究中，我们计划在热驱动循环反应器中开发一种由CO_2和甲醇合成DMC的新工艺。热驱动循环反应器具有用于反应的加热部分和用于排除水的冷却装置。催化剂为ZrO_2，脱水剂为3a分子筛。通过对相平衡和反应行为的研究，探索了反应条件的优化。特别评价了脱水剂用量对其性能的影响。在实验研究的基础上，进行了模型开发，并澄清了该过程的控制因素。首先，对脱水剂在甲醇-水体系高压反应介质中的性能进行了评价。结果表明，该脱水剂在热驱动环反应器（加热温度150 ~ 160℃，冷却温度60℃）中表现良好。其次，通过在文献基础上建立的模型，计算co_2 -甲醇-水- dmc体系的相平衡以探索单相区。在计算确定的反应条件下（反应器温度170℃，脱水温度25℃，压力15MPa），采用热驱动环反应器进行DMC合成。DMC产率最终达到15 mol%（基于甲醇的负载量），而在相同的反应条件下，间歇式反应器的DMC产率仅为1 mol%。建立了热驱动环反应器合成DMC的动力学模型，了解了反应过程的控制因素。通过模型分析可知，反应器内反应流体的流速是控制因素，必须对脱水装置进行改造以提高反应器的性能。少

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