离子液体作为正己烷/1-己烯精馏萃取剂的实验研究

Experimental Study on Ionic Liquid as Extractant in n-Hexane/1-Hexene Distillation

正己烷和1-己烯在石油化工行业中应用广泛。但是由于两者沸点较近,很难通过常规蒸馏实现分离。目前工业规模分离正己烷和1-己烯的技术包括膜法、萃取蒸馏法和有机溶剂液-液萃取法。其中一种具有良好应用前景的方法是以离子液体为萃取剂的萃取蒸馏法。对10种离子液体进行了筛选,评价萃取蒸馏正己烷和1-己烯混合物的效果。首先,测定了离子液体的萃取性能,以确定适用于正己烷/1-己烯萃取精馏的离子液体种类。优选出五种离子液体,即[4bmpy][TCM]、[4bmpy][Tf_(2)N]、[bmim]_(2)[Co(SCN)_(4)]、[P_(66614)][TCM]和[P_( 66614)][DCA]。其次,在65,85,105℃下进行了二元系统{n-己烷或1-己烯+离子液体}的汽液平衡实验,以优选保证均匀三元系统{n-己烷+1-己烯+离子液体}的最小溶剂进料比。在三种温度下,溶剂-进料质量比为9时,测定了{n-己烷+1-己烯+离子液体}三元体系的汽液平衡。此外,也测定了溶剂进料比为7和5的含有[P_(66614)]基离子液体。测得正己烷/1-己烯相对挥发度为2.4,超过其他离子液体和有机溶剂的相对挥发度。

N-hexane and 1-hexene are widely used in the petrochemical industry.However,due to the close boiling points,it is difficult to separate them by the conventional distillation.At present,the industrial scale separation technologies of n-hexane and 1-hexene include the membrane method,extractive distillation method and organic solvent liquid-liquid extraction method.One of the promising methods is the extractive distillation with ionic liquids as extractants.Ten kinds of ionic liquids were screened to evaluate the effect of extractive distillation of n-hexane and 1-hexene mixtures.To determine the kind of ionic liquids suitable for n-hexane/1-hexene extractive distillation,it measured the extraction performance of ionic liquids.Five kinds of ionic liquids are preferred,[4bmpy][TCM],[4bmpy][Tf_(2)N],[bmim]_(2)[Co(SCN)_(4)],[P_(66614)][TCM],and[P_(66614)][DCA].To optimize the minimum solvent feed ratio of homogeneous ternary system{n-hexane+1-hexene+ionic liquid},the vapor-liquid equilibrium experiments of binary system{n-hexane or 1-hexene+ionic liquid}were carried out at 65,85,105℃.The vapor-liquid equilibria of the ternary system{n-hexane+1-hexene+ionic liquid}were measured at three temperatures with a solvent feed mass ratio of 9.In addition,ionic liquids containing[P_(66614)]groups with solvent feed ratios of 7 and 5 were also measured.The relative volatility of n-hexane/1-hexene was 2.4,and it was higher than that of other ionic liquids and organic solvents.