以离子液体和分子液体混合溶剂为萃取剂萃取精馏分离乙腈—水共沸物

发布时间：2018-08-21 07:30

【摘要】：为解决离子液体萃取精馏中部分离子液体熔点高和粘度大的问题,本文采用离子液体和分子液体的混合物作为萃取剂,进行乙腈-水共沸体系的萃取精馏研究。实验测定了乙腈-水-乙二醇-氯化1-乙基-3-甲基咪唑([EMIM][Cl])四元体系在102.5 KPa下的汽-液平衡数据。将所测汽液平衡数据采用NRTL方程进行拟合,获得了[EMIM][Cl]-乙腈、[EMIM][Cl]-水、[EMIM][Cl]-乙二醇二元体系的交互作用参数,计算结果与实验测量结果吻合良好。实验结果表明以乙二醇+[EMIM][Cl]为混合萃取剂能完全打破乙腈-水共沸物的共沸点。此外,还测定了[EMIM][Cl]、乙二醇以及二者混合液的粘度,混合液粘度与离子液体相比大幅降低。通过比较[EMIM][Cl]和乙二醇在萃取剂中的作用得出:[EMIM][Cl]的选择性高于乙二醇的选择性,[EMIM][Cl]与乙二醇之间没有协同作用,混合萃取剂的选择性主要由[EMIM][Cl]贡献,乙二醇对混合萃取剂选择性贡献较小,乙二醇主要起助溶和降低离子液体粘度的作用。利用化工软件Aspen Plus进行了以[EMIM][Cl]和乙二醇为混合萃取剂分离乙腈-水共沸物的萃取精馏过程进行了模拟,确定了操作参数以及动态控制过程必需的设备参数。利用模拟计算研究了原料进料位置、萃取剂进料位置、萃取剂进料温度、回流比、溶剂比、混合萃取剂中离子液体含量对萃取精馏塔塔顶乙腈浓度以及再沸器热负荷的影响。利用化工软件Aspen Dynamic进行了萃取精馏动态控制过程研究,设计了3种不同的控制方案,并进行了动态控制模拟,向系统中加入±10%流量扰动、±10%浓度扰动,动态响应结果显示所设计的3种控制方案中,第2种控制方案能很好地克服操作中的扰动,为最优方案。
[Abstract]:In order to solve the problem of high melting point and high viscosity of some ionic liquids in extractive distillation of ionic liquids, the extraction distillation of acetonitrile-water azeotropic system was studied by using the mixture of ionic liquids and molecular liquids as extractant. The vapor-liquid equilibrium data of a quaternary system of acetonitrile-water-ethylene glycol 1-ethyl-3-methylimidazole chloride ([EMIM] [Cl]) at 102.5 KPa were measured. The vapor-liquid equilibrium data were fitted by NRTL equation, and the interaction parameters of [EMIM] [Cl] -acetonitrile, [EMIM] [Cl] -water, [EMIM] [Cl] -ethylene glycol were obtained. The calculated results are in good agreement with the experimental results. The experimental results show that the mixture of ethylene glycol [EMIM] [Cl] can completely break the azeotropic point of acetonitrile-water azeotrope. In addition, the viscosity of [EMIM] [Cl], ethylene glycol and their mixtures were also determined. The viscosity of the mixture was significantly lower than that of ionic liquids. By comparing the effects of [EMIM] [Cl] and ethylene glycol in extractant, it is concluded that the selectivity of [EMIM] [Cl] is higher than that of ethylene glycol, and there is no synergistic effect between [EMIM] [Cl] and ethylene glycol, and the selectivity of mixed extractant is mainly contributed by [EMIM] [Cl]. Ethylene glycol contributes little to the selectivity of the mixed extractant. Ethylene glycol plays a major role in solubilizing and reducing the viscosity of ionic liquids. The extraction distillation process of acetonitrile-water azeotrope separation with [EMIM] [Cl] and ethylene glycol as mixed extractant was simulated by using chemical software Aspen Plus. The operating parameters and the equipment parameters necessary for dynamic control process were determined. The effects of feed position, feed temperature, reflux ratio, solvent ratio and ionic liquid content on the concentration of acetonitrile at the top of the column and the heat load of the reboiler were studied by simulation. The dynamic control process of extractive distillation was studied by using chemical software Aspen Dynamic. Three different control schemes were designed, and the dynamic control simulation was carried out. 卤10% flux disturbance and 卤10% concentration disturbance were added to the system. The results of dynamic response show that the second control scheme can overcome the disturbance well and is the optimal scheme.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ028.3

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