在101.32 kPa下,用改进的Othmer釜测定了甲醇-苯与三种离子液体的三元物系的等压汽液平衡数据,即甲醇-苯-1-乙基-3-甲基咪唑四氟硼酸盐([EMIM]BF4),甲醇-苯-1-丁基-3-甲基咪唑四氟硼酸盐([BMIM]BF4),甲醇-苯-1-辛基-3-甲基咪唑四氟硼酸盐([OMIM]BF4)。实验结果表明,加入离子液体可以使汽液平衡线偏离甲醇-苯二组分物系的汽液平衡线,离子液体摩尔分数越大,偏离程度越大。[OMIM]BF4表现出明显的盐析效应,使甲醇对苯的相对挥发度发生改变,消除了甲醇—苯物系的共沸点。离子液体对甲醇的盐析效应顺序为:[OMIM]BF4 >[BMIM]BF4 >[EMIM]BF4。因此[OMIM]BF4 可以作为甲醇-苯物系萃取精馏的溶剂。
Abstract
Isobaric vapor-liquid equilibrium data for methanol-benzene-ionic liquid ternary systems have been measured at 101.32 kPa using a modified Othmer still. The ionic liquids employed were 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM]BF4), 1-butyl-3-methylimidazolium tetrafluoroborate([BMIM]BF4) and 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIM]BF4). The vapor-liquid equilibrium curves of the methanol-benzene-ionic liquid systems deviate from that of the IL-free system and the deviation increases with increasing amounts of IL. The [OMIM]BF4 shows a salt-out effect, which increase the volatility of methanol relative to that of benzene, and even leads to an elimination of the azeotropic point. The salting-out effect on methanol decreases in the order: [OMIM]BF4 > [BMIM]BF4 > [EMIM]BF4. As a result, it is concluded that [OMIM]BF4 can be used as an entrainer for the separation of methanol and benzene, and the VLE data obtained here can be used to optimize the process.
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脚注
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