基于COSMO-RS方法筛选离子液体分离乙酸乙酯-乙腈共沸物

采用COSMO-RS方法探究了不同离子液体在分离乙酸乙酯-乙腈共沸物系中的应用；通过预测值与实验值的对比，验证了COSMO-thermX预测离子液体分离效果的准确性。离子液体的选择性和不同离子液体对乙酸乙酯-乙腈近沸点处相对挥发度的影响为指标，计算和分析了17种阳离子和13种阴离子组成的221种离子液体对乙酸乙酯-乙腈共沸物系的分离效果的影响规律。结果表明，含有OAc]^－和Cl]^－的离子液体对于乙酸乙酯-乙腈混合物的分离具有更好的促进效果，而阳离子的变化对于乙酸乙酯-乙腈混合物分离的促进效果差异较小。应用表面电荷密度分布（σ-profile）进一步研究了阴离子OAc]^－和Cl]^－对共沸物的影响，研究发现，阴离子OAc]^－和Cl]^－对乙酸乙酯-乙腈的分离效果影响顺序为OAc]^－>Cl]^－；综合筛选结果，得出离子液体BMIM]OAc]有望在乙酸乙酯-乙腈共沸混合物分离过程中成为一种高效的萃取剂。

Screening of ionic liquids for separation of ethyl acetate-acetonitrile azeotrope based on COSMO-RS

The application of different ionic liquids in the separation of acetate-acetonitrile azeotrope was investigated by COSMO-RS method. The accuracy of COSMO-thermX prediction of ionic liquid separation was verified by comparison between predicted and experimental values. The selectivity (based on acetonitrile) of 221 ionic liquids composed of 17 cations and 13 anions and the effect of ionic liquids on the relative volatility of ethyl acetate to acetonitrile near azeotropic point were calculated and analyzed. It was found that the ionic liquids containing OAc]^- and Cl]^- had a better promoting effect on the separation of ethyl acetate - acetonitrile mixture, while the difference in the promoting effect of cations on the separation of ethyl acetate - acetonitrile mixture was small. The effect of anions OAc]^- and Cl]^- on azeotrope was further studied by applying the surface charge density distribution (σ-profile), revealing that the order of influence of the anions OAc]^- and Cl]^- on the separation of ethyl acetate-acetonitrile was OAc]^->Cl]^-. The comprehensive prediction results show that ionic liquid BMIM]OAc] is expected to be used as a highly efficient extractant in the separation of ethyl acetate-acetonitrile mixture.