环氧氯丙烷、甲醇和二氧化碳一步直接催化合成碳酸二甲酯的研究

One-Pot Synthesis of Dimethyl Carbonate from Epichlorohydrin, Methanol and Carbon Dioxide

以生物柴油副产物甘油为原料合成碳酸二甲酯新工艺既能减少对石油的依赖,又能充分利用生物质资源。本研究首先对环氧氯丙烷和环氧丙烷分别为原料合成碳酸二甲酯反应体系进行了热力学分析和对比,计算了不同反应温度和压力下的碳酸二甲酯平衡收率。环氧氯丙烷作为原料较环氧丙烷在热力学上具有明显优势,在3.0 MPa、460 K时,其平衡收率分别为90.4%和18.2%。在此基础上,考察了碱金属化合物、负载型碱金属催化剂、季铵盐及其复合催化剂等对环氧氯丙烷与甲醇和二氧化碳直接合成碳酸二甲酯的催化反应性能。实验结果表明,钠金属化合物为催化剂时的碳酸二甲酯收率高于钾金属化合物。负载型催化剂Na2CO3(Na HCO3)/γ-Al2O3的催化活性较均相催化剂明显提高,碳酸二甲酯的收率达到21.0%左右。发现四丁基溴化铵与碳酸氢钠混合物作为催化剂可显著提高碳酸二甲酯收率,达到25.2%。

Dimethyl carbonate was synthesized from glycerol, a by-product in the production of biodiesel, as a raw material in this paper. The novel synthetic process may not only reduce dependence on fossil oil, but also fully utilize biomass resources. Using epichlorohydrin and propylene epoxide as the raw material, the thermodynamic analysis for reactions of dimethyl carbonate synthesis was conducted respectively. It was found that the reaction of using epichlorohydrin as raw material is much more thermodynamically favorable than that of using propylene epoxide, and under 3 MPa and 460 K, the equilibrium yields of dimethyl carbonate are 90.4% and 18.2%, respectively. Based on above results, the influences of various catalysts, including alkali-metal compounds, supported alkali-metal compounds and the mixtures of n-Bu4NBr and alkali-metal compounds catalyst on the synthesis of dimethy carbonate from epichlorohydrin, methanol and carbon dioxide were studied. The results show that the yield of dimethyl carbonate by sodium compounds is higher than that by potassium compounds. A mixture of n-Bu4NBr and NaHCO3 was used as a catalyst, critical to improve the yield of dimethyl carbonate （25.2%）.