酯交换法合成碳酸甲乙酯研究进展

Recent advances of studies in ethyl methyl carbonate synthesis via transesterification process

碳酸甲乙酯(EMC)具有诸多优异的物理和化学性能,作为锂电池电解液溶剂已经被行业广泛认可,酯交换法是中国目前工业生产EMC的主要方法。本研究系统综述了碳酸酯交换反应热力学、动力学、均相及非均相催化剂、反应机理及反应工艺等方面的研究,重点评述了近五年酯交换法制备EMC的最新进展。均相催化剂中以pK_b值(碱度系数)为标准讨论了可溶碱类催化剂碱强度和催化效率之间的关系,探究了咪唑类离子液体阴、阳离子结构对反应效果的影响规律。针对工业上普遍采用的甲醇钠催化剂,描述了其失活现象并阐述了失活机理。详细比较和讨论了非均相催化剂的制备方法、表面酸碱性与催化效率之间的关系,综合评价了不同类别的催化剂催化酯交换反应的优缺点。着眼绿色、高纯、低成本EMC合成技术,高效固体碱催化剂和涉及气、液、固三相的催化精馏技术是今后开发的重点和发展方向。

Ethyl methyl carbonate(EMC) has been widely used as a solvent in electrolyte of lithium-ion batteries due to its outstanding physico-chemical properties. The transesterification method has been industrially applied to produce EMC owing to its excellent efficiency, simple synthesis processing and high product purity. This article systematically reviewed the advances in EMC synthesis via the transesterification approach, including the thermodynamics, kinetics, homogeneous and heterogeneous catalysts, reaction mechanism and reaction engineering, particularly focusing on new progress in the last five years. For homogeneous catalysts, the relationship between alkali strength and catalytic efficiency was discussed based on pK_b(alkalinity coefficient). The effects of different anion and cation structures on the catalytic performances of imidazole ionic liquids were also investigated. A possible deactivation mechanism of the sodium methoxide catalyst, which was widely applied in manufacture, was proposed. The effects of different preparation methods, surface acidity and basicity of heterogeneous catalysts on catalytic efficiency were critically reviewed and discussed. The advantages and disadvantages of as-reported catalysts with various types were carefully compared. The future studies should focus on the solid base catalyst with higher efficiency and three-phase catalytic distillation technology.