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乙酸乙酯-乙醇-离子液体等压汽液平衡数据的测定
Isobaric vapor-liquid equilibria for ethyl acetate-ethanol-ionic liquid ternary systems
在101.32kPa下，用改进的Othmer釜测定了两种乙酸乙酯-乙醇-离子液体三元物系的等压汽液平衡数据，即乙酸乙酯-乙醇-1-丁基-3-甲基咪唑四氟硼酸盐(［BMIM］BF4)与乙酸乙酯-乙醇-1-辛基-3-甲基咪唑四氟硼酸盐(［OMIM］BF4)。实验结果表明：加入［BMIM］BF4和［OMIM］BF4，汽液平衡线偏离乙酸乙酯-乙醇物系的汽液平衡线；离子液体摩尔分数越大，偏离程度越大；［BMIM］BF4与［OMIM］BF4表现出明显盐效应，使乙酸乙酯对乙醇的相对挥发度发生改变，均消除了乙酸乙酯-乙醇物系的共沸点。离子液体对乙酸乙酯的盐析效应顺序为：［OMIM］BF4>［BMIM］BF4。因此，［BMIM］BF4和［OMIM］BF4可以作为乙酸乙酯-乙醇物系萃取精馏的溶剂，汽液平衡数据的测定可为分离过程优化设计提供依据。
Isobaric vapor-liquid equilibrium data for ethyl acetate-ethanol-ionic liquid ternary systems were measured in a modified Othmer still at 101.32kPa. The ionic liquids employed were 1-butyl-3-methylimidazolium tetrafluoroborate (［BMIM］BF4) and ethyl 1-octyl-3-methylimidazolium tetrafluoroborate (［OMIM］BF4). The vapor-liquid equilibrium curves of the ethyl acetate-ethanol-ionic liquid systems deviate from that of the IL-free system and the deviation increases with increasing amounts of IL. The ILs show a salting-out effect, which increases the volatility of ethyl acetate relative to that of ethanol, and even leads to an elimination of the azeotropic point. The salting-out effect on ethyl acetate decreases in the order: ［OMIM］BF4>［BMIM］BF4. As a result, it is concluded that ［BMIM］BF4 and ［OMIM］BF4 can be used as entrainers for the separation of ethyl acetate and ethanol, and the VLE data obtained here can be used to optimize the process.
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