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通过萃取精馏法,以N-甲基吡咯烷酮(NMP)为萃取剂分离乙酸乙酯-正庚烷的共沸物系。利用溶剂选择原理和UNIFAC基团贡献法筛选N-甲基吡咯烷酮作为萃取精馏的萃取剂,同时通过常压下乙酸乙酯-正庚烷体系和加入萃取剂N-甲基吡咯烷酮后的气液平衡实验,证明N-甲基吡咯烷酮能够打破共沸。并进行间歇萃取精馏实验,填料塔理论塔板数为35,回流比1.0,可以得到质量分数为98.3%的正庚烷,回收率为73.4%。最后在Aspen Plus软件帮助下研究N-甲基吡咯烷酮连续萃取精馏分离乙酸乙酯-正庚烷物系的工艺流程,萃取精馏塔塔顶正庚烷的质量分数可达99.5%,溶剂回收塔塔底回收纯N-甲基吡咯烷酮套用,为进一步的工业应用提供依据。
The azeotropic system of ethyl acetate-n-heptane was separated by extractive distillation with N-methylpyrrolidone (NMP) as extractant. N-methylpyrrolidone was selected as extractant of extractive distillation by solvent selection principle and UNIFAC group contribution method. At the same time, the extractant was extracted by ethyl acetate-n-heptane system under atmospheric pressure and gas-liquid Equilibrium experiments show that N-methylpyrrolidone can break the azeotrope. The experiment of batch extractive distillation was carried out. The theoretical plate number of the packed tower was 35 and the reflux ratio was 1.0. The mass fraction of n-heptane was 98.3%. The recovery rate was 73.4%. Finally, with the help of Aspen Plus software, the process of N-methylpyrrolidone continuous extractive distillation to separate the ethyl acetate-n-heptane system was studied. The mass fraction of n-heptane in the top of the extractive distillation column was up to 99.5% The recovery of pure N-methylpyrrolidone from the bottom of the column provides the basis for further industrial application.