离子液体萃取精馏分离苯-环己烷物系

在0.101 MPa 下,测定了不同离子液体对苯-环己烷物系相对挥发度的影响,研究了萃取剂比(萃取剂与原料液的体积比)对物系相对挥发度的影响以及离子液体加入速率和回流比对萃取精馏的影响,按实验确定的最佳工艺条件进行了重复实验。实验结果表明,离子液体作为萃取剂可以消除苯-环己烷物系的共沸点,提高苯-环己烷物系的相对挥发度。采用1-丁基-3-甲基咪唑六氟磷酸盐作为萃取剂,在萃取剂比为0.6、离子液体加入速率为6 mL/min、回流比为2.5的条件下,可得到纯度大于98.0%的环己烷。采用闪蒸的方法分离塔釜液,可回收苯和离子液体。

Separation of Benzene-Cyclohexane by Extractive Distillation with Ionic Liquid

Effect of different ionic liquids on relative volatilities of benzene-cyclohexane system was determined at 0.101 MPa.Effect of extractant ratio(volume ratio of extractant and material)on relative volatility of benzene-cyclohexane system,and effect of flow rate of ionic liquid and reflux ratio on purity and output of overhead fraction of the extractive distillation column with ionic liquid were studied.Repeated experiments were carried out under the determined optimum experimental conditions.The azeotropic point of benzene-cyclohexane system is eliminated in extractive distillation with ionic liquid and relative volatility of cyclohexane to benzene increases.The purity of cyclohexane is over 98.0% when 1-butyl-3-methylimidazolium hexafluorophosphate is used as extractant,extractant ratio 0.6,flow rate of ionic liquid 6 mL/min and reflux ratio 2.5.Comparing with regular extractive distillation,extractive distillation with ionic liquid makes small extractant ratio possible and can obtain high purity of cyclohexane.By flash distillation of residue,benzene and ionic liquid can be separated.