Abstract: n-Butyl acetate (NBA), a key organic chemical intermediate, is widely applied in coatings, paints, inks, printing, electronics, and leather processing. The primary method for NBA production is the esterification of n-butanol. During this process, a mixture of n-butanol and NBA is produced, and it is necessary to separate them. However, the azeotrope formed between NBA and n-butanol at atmospheric pressure makes conventional distillation ineffective. In this work, three ionic liquids (ILs), 1-ethyl-3-methylimidazolium acetate ([EMIM][AC]), 1-ethyl-3-methylimidazolium dimethyl phosphate ([EMIM][DMP]), and 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]) were screened as extractants using the COSMOthermX software based on COSMO-RS theory, with selectivity as the main indicator, combined with the viscosity of ILs. Liquid-liquid equilibrium (LLE) data for the ternary systems (n-butanol+NBA+ILs) were measured at 303.15 K and atmospheric pressure. The reliability of the LLE data was verified via Othmer-Tobias, Bachman, and Hand equations. The extraction performance of the three ILs was evaluated by selectivity and distribution coefficient, and the non-random two-fluid (NRTL) model was used to correlate the LLE data. Finally, the separation mechanism of the three ILs was explored by means of σ-profile and σ-potential analysis. The results indicated that the linear correlation coefficients (R2) of the Othmer-Tobias, Bachman, and Hand equations for the ternary LLE data all exceed 0.95, demonstrating high reliability of the data obtained in this work. The distribution coefficients (D) and selectivity (S) of the three ILs were all greater than 1, confirming their suitability for separating the n-butanol and NBA mixture. The separation performance followed the order of [EMIM][AC]>[EMIM][DMP]>[EMIM][DEP]. All three ILs were deemed suitable for separating the n-butanol and NBA mixture. The root mean square deviation (RMSD) between the results calculated by the NRTL model and the experimental data was less than 3%, indicating that the NRTL model was highly applicable for describing the LLE behavior of the n-butanol-NBA-IL ternary system studied in this work. There was a stronger hydrogen bond interaction between ILs and n-butanol, so ILs could separate n-butanol from its mixtures with NBA. The order of the interaction strength between the three ILs and n-butanol was [EMIM][AC]>[EMIM][DMP]>[EMIM][DEP].

Key words: n-butyl acetate, n-butanol, ionic liquids, liquid-liquid extraction, non-random two-fluid (NRTL), model, σ-profile, σ-potential

摘要： 乙酸正丁酯是重要的有机化工原料，广泛应用于涂料、油漆、油墨、印刷、电子工业、皮革加工等领域。正丁醇酯化法是制备乙酸正丁酯的主要方法，此过程会产生正丁醇和乙酸正丁酯的混合物，需对二者进行分离。然而，常压下二者会形成共沸物，传统精馏无法实现高纯分离。本研究基于COSMO-RS理论的COSMOthermX软件，以选择性为主要指标，结合离子液体黏度等因素，筛选出1-乙基-3-甲基咪唑醋酸盐([EMIM][AC])、1-乙基-3-甲基咪唑磷酸二甲酯([EMIM][DMP])和1-乙基-3-甲基咪唑磷酸二乙酯([EMIM][DEP])三种离子液体作为萃取剂。在常压、303.15 K下，测定了正丁醇-乙酸正丁酯-离子液体三元体系的液液相平衡(LLE)数据，采用Othmer-Tobias, Bachman和Hand方程对LLE数据进行可靠性检验，通过选择性和分配系数比较三种离子液体的萃取性能，并使用非随机双液体(NRTL)模型对LLE数据进行关联。最后，通过σ-profile和σ-potential分析，对三种离子液体萃取分离正丁醇-乙酸正丁酯共沸体系机理进行了探讨。结果表明，Othmer-Tobias, Bachman和Hand方程对三元LLE数据的线性相关系数R2均大于0.95，实验所得相平衡数据具有较高的可靠性；三种离子液体的分配系数和选择性均大于1，均可用于分离正丁醇和乙酸正丁酯混合物，分离性能大小顺序为[EMIM][AC]>[EMIM][DMP]>[EMIM][DEP]；NRTL模型计算值与实验结果的RMSD均小于3%，NRTL模型描述本研究三元体系的LLE行为具有良好的适用性；离子液体与正丁醇间具有更强的氢键相互作用，因此，离子液体可将正丁醇从其与乙酸正丁酯的混合物中萃取分离，三种离子液体与正丁醇的相互作用大小顺序为[EMIM][AC]>[EMIM][DMP]>[EMIM][DEP]。

关键词: 乙酸正丁酯, 正丁醇, 离子液体, 液液萃取, 非随机双液体(NRTL), 模型, σ-profile, σ-potential