几种离子液体对甲醇—甲乙酮体系的汽液相平衡及其萃取精馏计算机模拟的研究

发布时间：2018-06-09 04:36

本文选题：汽液相平衡 + 离子液体　；参考：《北京化工大学》2017年硕士论文

【摘要】：甲醇和甲乙酮是工业生产中常见的溶剂和化工合成的原料,二者形成共沸物,非特殊手段不能分离。近年来,离子液体作为萃取剂进行共沸物的萃取精馏成为一个研究热点。离子液体结合了传统有机溶剂和固体盐的优点,作为萃取剂具有选择性高、溶剂比小、易操作、安全环保等特点。本文针对甲醇-甲乙酮共沸物系,首先筛选出了合适的离子液体,继而测得了含离子液体体系的汽液相平衡数据,分析了离子液体对共沸体系的影响,并研究常用活度系数模型对含离子液体多元体系的适用性,最后对离子液体萃取精馏过程进行了计算机模拟。主要工作如下:1、利用UNIFAC模型计算了 19种离子液体对甲醇-甲乙酮体系的在无限稀释条件下的选择性和溶剂能力,定义并计算了共沸组成下的相对挥发度增强因子EF。通过比较发现不同阴离子的选择性和溶剂能力差异较大,其大小排序:[NTf2] [PF6] [OTf] [BF4] [SCN] [DMP]。通过分析研究增强因子 EF,进一步发现[EMIM][NTf2]、[BMIM][NTf2]和[HMIM][NTf2]三种离子液体对甲醇-甲乙酮体系的萃取分离能力较强,并预测了含离子液体的三元体系的汽液相平衡。2、在101.3 kPa下利用改进的Othmer汽液相平衡釜测定了甲醇-甲乙酮-[EMIM][NTf2]、甲醇-甲乙酮-[BMIM][NTf2]和甲醇-甲乙酮-[HMIM][NTf2]三个体系的汽液相平衡数据。实验数据表明,三种离子液体对体系均存在较强的盐效应,降低了甲乙酮在体系中的活度系数,从而使得甲醇在汽相中的含量增加,增大了体系的相对挥发度。在离子液体液相摩尔分数大于0.05时,就可以完全打破甲醇-甲乙酮共沸。三种离子液体萃取分离效果排序:[HMIM][NTf2] [BMIM][NTf2] [EMIM][NTf2]。3、采用四种活度系数模型Wilson、NRTL、UNIQUAC和e-NRTL对甲醇-甲乙酮体系和甲醇-甲乙酮-离子液体三元体系的汽液相平衡数据进行了回归并得到模型参数。Wilson、NRTL和UNIQUAC均能够较好地再现实验数据,平均相对偏差较小,不超过2%,对含离子液体体系具有较强的适用性。e-NRTL回归的平均相对偏差较大,不适合用来回归含离子液体的多元体系。此外,研究发现UNIFAC模型的预测结果在离子液体浓度较低时较准确。4、利用Aspen Plus软件,采用NRTL模型,对离子液体做萃取剂萃取精馏分离甲醇和甲乙酮的工艺过程进行计算模拟,得到了质量合格的产品,并优化了设备和操作参数,三种离子液体的萃取效果排序:[HMIM][NTf2] [BMIM][NTf2] [EMIM][NTf2]。模拟结果与二乙基酮作萃取剂进行了比较,发现了离子液体做萃取剂的诸多优势。最后研究了萃取精馏塔内汽液分布和塔内温度分布,确定了灵敏板的位置。
[Abstract]:Methanol and methyl ethyl ketone are common solvents and raw materials for chemical synthesis in industrial production. They form azeotrope and can not be separated by special means. In recent years, the extraction distillation of azeotrope with ionic liquid as extractant has become a research hotspot. Ionic liquids combine the advantages of traditional organic solvents and solid salts. As extractants, they are characterized by high selectivity, low solvent ratio, easy operation, safety and environmental protection. In this paper, a suitable ionic liquid was screened out for the methanol-methyl ethyl ketone azeotrope system, then the vapor liquid equilibrium data of the ionic liquid system were measured, and the effect of ionic liquid on the azeotropic system was analyzed. The applicability of the commonly used activity coefficient model to the ionic liquid multicomponent system was studied. Finally, the extraction distillation process of the ionic liquid was simulated by computer. The main work is as follows: 1. The selectivity and solvent ability of 19 ionic liquids to methanol-methyl ethyl ketone system under infinite dilution are calculated by UNIFAC model. The relative volatilization enhancement factor (EF) under azeotropic composition is defined and calculated. It was found that the selectivity and solvent ability of different anions varied greatly, and the order of their size was as follows: [NTf2] [PF6] [OTF] [BF4] [SCN] [DMP]. By analyzing the enhancement factor EF2, it was further found that three ionic liquids [EMIM] [NTf2], [BMIM] [NTf2] and [HMIM] [NTf2] had strong extraction and separation ability for methanol-methyl ethyl ketone system. The vapor-liquid equilibrium of ternary system containing ionic liquids was predicted. The vapor-liquid equilibrium data of three systems, methanol-methyl ethanone [EMIM] [NTf2], methanol-methyl ethanone [BMIM] [NTf2] and methanol-methyl ethanone [HMIM] [NTf2], were determined by using the modified Othmer vapor-liquid equilibrium kettle at 101.3 KPA. The experimental data show that the three ionic liquids have strong salt effect and decrease the activity coefficient of methyl ethyl ketone in the system, thus increasing the content of methanol in the vapor phase and increasing the relative volatilization of the system. When the liquid phase molar fraction of ionic liquid is greater than 0.05, the azeotropic effect of methanol and methyl ethyl ketone can be completely broken. The extraction and separation effects of three kinds of ionic liquids were ranked as follows: [HMIM] [NTf2] [BMIM] [NTf2] [EMIM] [NTf2] [NTf2] .3.The vapor-liquid equilibrium data of methanol-methyl ethanone system and methanol-methyl ethane-ionic liquid ternary system were regressed using four activity coefficient models, Wilsonian NRTL UNIQUAC and e-NRTL. The model parameters. Wilsonian NRTL and UNIQUAC can reproduce the experimental data well. The average relative deviation is smaller and less than 2. It is applicable to the ionic liquid system. The average relative deviation of e-NRTL regression is large, so it is not suitable to be used to regress the multicomponent system containing ionic liquid. In addition, it is found that the predicted results of UNIFAC model are more accurate when the concentration of ionic liquids is low. By using Aspen Plus software and NRTL model, the process of separation of methanol and methyl ethyl ketone by extractive distillation with ionic liquids as extractant is calculated and simulated. The high quality products were obtained, and the equipment and operation parameters were optimized. The extraction effects of three kinds of ionic liquids were ranked as follows: [HMIM] [NTf2] [BMIM] [NTf2] [EMIM] [NTf2] [NTf2]. The simulation results were compared with that of diethylketone as extractant, and many advantages of ionic liquid as extractant were found. Finally, the vapor-liquid distribution and temperature distribution in the extraction distillation column were studied, and the position of the sensitive plate was determined.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O642.42

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