Abstract: The efficient separation of alcohol-nitrile azeotropes produced in chemical production is a difficult problem in the chemical industry, and the widely used extractive distillation techniques in this field have put forward further requirements for the selection of extractants and mechanism analysis. The COSMO-RS model can be used to predict the thermodynamic properties of the fluid through quantitative calculation, and select the ionic liquids (ILs) extractant agent suitable for a certain system from a large number of possible solvents, which can significantly reduce the experimental amount and enhance the research efficiency. By comparing the model prediction value with the experimental value, the accuracy of the COSMO-thermX software in predicting the separation of alcohol and nitrile azeotropes by ionic liquid has been verified. Based on the COSMO-RS model, with the separation selectivity of ILs, the influence of ILs on the relative volatility of isopropyl alcohol (IPA)-acetonitrile (MeCN) near boiling point and the solubility of ILs to IPA as indexes, the effects of 456 ILs composed of 24 cations and 19 anions on the separation of IPA-MeCN azeotrope were calculated and analyzed. The results showed that ammonium tetraethylacetate ([N2,2,2,2][Ac]) was the best extractant. The interaction between IPA-MeCN molecules in the mixture and [N2,2,2,2][Ac] was studied by means of excess enthalpy analysis, interaction energy analysis and weak interaction analysis, and the separation mechanism of [N2,2,2,2][Ac] as an extractant for separating IPA-MeCN at molecular level was discussed, and the results showed that the interaction between [N2,2,2,2][Ac] and IPA was stronger than that with MeCN, thereby accelerating the disruption of the original azeotropic structure. The assistance of the COSMO-RS model in screening ILs extractants and analyzing separation mechanisms provided important information for further understanding the function of ionic liquid in azeotropic system separation, and had important reference value for the development of novel extractive distillation technologies.

Key words: isopropyl alcohol, acetonitrile, ionic liquid, COSMO-RS model, separation mechanism

摘要： 高效分离化工生产中产生的醇腈类共沸物是化学工业领域的一项难题，该领域中应用较广泛的萃取精馏技术对萃取剂的选择及机理分析提出了更进一步的要求。利用COSMO-RS模型辅助，通过量化计算预测流体热力学性质，从大量可能溶剂中筛选出适用于某一混合体系的离子液体(ILs)萃取剂，可显著减少实验量，提高研究效率。通过模型预测值与实验值的对比，验证了COSMO-thermX软件预测离子液体分离醇腈共沸物效果的准确性。以ILs的分离选择性、ILs对异丙醇(IPA)-乙腈(MeCN)混合物近沸点处相对挥发度的影响以及ILs对于IPA的溶解度为指标，分析了由24种阳离子和19种阴离子组成的456种ILs对IPA-MeCN的分离效果的影响规律。筛选得到四乙基醋酸铵([N2,2,2,2][Ac])为最佳萃取剂。进一步利用超额焓分析、相互作用能分析和弱相互作用分析等方法研究混合物中IPA、MeCN分子与[N2,2,2,2][Ac]的相互作用，探讨了[N2,2,2,2][Ac]为萃取剂分离IPA-MeCN的分子间分离作用机理。结果表明，[N2,2,2,2][Ac]与IPA之间的相互作用强于MeCN，从而加速了原有共沸结构的破坏。COSMO-RS模型辅助筛选ILs萃取剂及分离机理分析为进一步了解离子液体在共沸体系分离中的作用提供了重要的信息，对新型萃取精馏技术中萃取剂的开发具有一定的参考价值。

关键词: 异丙醇, 乙腈, 离子液体, COSMO-RS模型, 分离机理