异丁醇-水-1-丁基-3-甲基四氟硼酸咪唑盐物系等压汽液平衡数据的测定

在101.32 kPa下,用改进的Othmer釜测定了含离子液体1-丁基-3-甲基四氟硼酸咪唑盐(BMIM]BF4)的异丁醇-水物系的等压汽液平衡数据。实验结果表明,当BMIM]BF4的摩尔分数为10%时异丁醇-水二组分物系的汽液平衡线就开始偏离,BMIM]BF4摩尔分数为20%,30%时,偏离程度越大;BMIM]BF4表现出盐效应,使异丁醇对水的相对挥发度发生改变,消除了异丁醇-水物系的共沸点;BMIM]BF4含量越大,盐效应越明显,随着BMIM]BF4含量的增加,异丁醇对水的相对挥发度也随着增加。BMIM]BF4可以做为异丁醇-水物系萃取精馏分离的有机盐,适宜的BMIM]BF4摩尔分数为20%。

Isobaric vapor-liquid equilibria for the isobutanol-water-1-butyl-3-methylimidazolium tetrafluoroborate ternary system

Isobaric vapor-liquid equilibrium data for the isobutanol-water system containing the ionic liquid(IL) 1-butyl-3-methylimidazolium tetrafluoroborate(BMIM]BF_4)were measured in a modified Othmer still at 101.32 KPa.The vapor-liquid equilibrium curve for the isobutanol-water with added IL deviates from that of the binary system when the mole fraction of BMIM] BF_4 reaches 10%.When the mole fraction ofBMIM]BF_4 is 20% or 30%,the deviation is greater.The IL shows a salt effect,which increases the volatility of isobutanol relative to that of water,and even leads to the disappearance of the azeotropic point.Increasing addition ofBMIM]BF_4 results in the salt effect becoming more distinct,and the volatility of isobutanol relative to water increases.As a result,it is concluded that BMIM] BF_4 can be employed as a salt in the extractive distillation of the isobutanol-water system.The optimum mole fraction of BMIM]BF_4 is about 20%,and the VLE data obtained allow the design of the process to be optimized.