Thesis Advisor华超
Degree Grantor中国科学院研究生院
Degree Name硕士
Degree Discipline化学工程

苯和环己烷是芳烃和非芳烃体系中最难分离的二元组分,探寻苯和环己烷的高效分离技术一直是当前石油化工分离领域探究的热点之一。萃取精馏是芳烃和非芳烃分离的常用工艺,一般使用二甲基亚砜、环丁枫等作为萃取剂,但是存在萃取剂相对用量大、易挥发、能耗高、投资高等缺点。因此开发绿色高效萃取剂一直是芳烃分离领域的研究热点。本文根据低共熔溶剂结构、性质与氢键供体和受体的组合可改变的特点,制备了三种低共熔溶剂DES1、DES2和DES3,系统研究了低共熔溶剂的物性特征和结构,在常压常温下进行苯-环己烷-低共熔溶剂的气液相平衡实验,分析筛选出最佳萃取剂为DES1,最佳氢键受体和供体摩尔配比为1:2,萃取剂的最佳使用摩尔浓度为0.1(溶剂比为0.263),评价了萃取剂的萃取效果:加入DES1(1:2)(摩尔浓度0.1)体系的相对挥发度全浓度范围内大于1(ɑ>1),打破了共沸物,萃取剂用量最少,具有最好的萃取效果;加入其他DES的体系相对挥发度不是在全浓度范围内大于1,未打破共沸,无萃取效果。针对低共熔溶剂的设计和优化过程进行气液平衡模型化研究,利用UNIQUAC、NRTL和Wilson三种热力学模型对苯-环己烷-低共熔溶剂气液相平衡数据进行拟合,通过比较相关指数R2选择最佳适用热力学模型为NRTL,得出了模型参数。其中苯-环己烷-DES1(1:2)(摩尔浓度0.1)体系R2为0.8771,NRTL模型二元交互作用参数为:Aij,-17.895;Aji,26.168;Bij,10000;Bji,-10000;Cij,0.1717(i=环己烷,j=苯)。红外光谱和核磁共振波谱结果表明有萃取效果的低共熔溶剂即DES1(1:2)与苯之间存在较强的氢键和π–π键作用,这种作用可以打破了苯和环己烷共沸物;无萃取效果的低共熔溶剂与苯之间的氢键和π–π键作用较弱,验证了低共熔溶剂的筛选结果。 ;It is the most difficult to separate benzene-cyclohexane binary components in aromatics and non-aromatics separation field and also has been one of the hot topics in the field of petrochemical separation. Extractive distillation is the common method in aromatics and aromatics separation process, the general extraction agent is dimethyl sulfoxide, sulfolane , et al., but there are many disadvantages of extractant, such as relative large usage, volatility, high energy consumption, high investment. Therefore, the study of green and efficient extractant is a research hotspot in this field.Three deep eutectic solvents (DES1, DES2 and DES3) are prepared in this work according to that the structure and properties of deep eutectic solvents can be changed according to the combination of hydrogen bond donor and hydrogen bond acceptor. The physical properties and structure of the deep eutectic solvents are systematically studied. And they were used in benzene-cyclohexane-extractant vapor-liquid phase equilibrium experiments under the atmospheric pressure at room temperature. The results showed that the best extractant was DES1, the best molar ratio for hydrogen bond acceptor and hydrogen bond donor was 1:2 and the optimum molar concentration is 0.1 (solvent ratio, 0.263). The extractive distillation effect of prepared deep eutectic solvents was evaluated: the relative volatility of ternary system with DES1 (1:2) (0.1) is greater than 1 in all the range of concentration (ɑ>1), and DES1 (1:2) (0.1) broke the azeotrope has least extracting agent dosage; the relative volatility of ternary system with other DESs is not greater than 1 in all the range of concentration, they did not break the azeotrope and have no extraction effect.Three thermodynamic models (NRTL, Wilson, and UNIQUAC) were used to fit vapor-liquid phase equilibrium data. According to the result of correlation index R2, the best applicable thermodynamic model is NRTL and its model parameters were obtained: in the system of benzene-cyclohexane-DES1 (1:2) (0.1), R2 is 0.8771; binary interaction parameters of NRTL model is: Aij, 17.895; Aji, 26.168; Bij, 10000; Bji, -10000; Cij, 0.1717 (i=cyclohexane, j=benzene).Infrared spectrum and nuclear magnetic resonance spectrum show that the deep eutectic solvent which has extraction effect has hydrogen bonding and π–π interaction with benzene, this interaction can break benzene and cyclohexane azeotrope. The deep eutectic solvent which has no extraction effect has weak hydrogen bonding and π–π interaction interaction with benzene and the interaction can not break the azeotrope. Therefor, deep eutectic solvent screening result was verified. 

Document Type学位论文
Recommended Citation
GB/T 7714
李静. 低共熔溶剂在苯和环己烷萃取精馏中的应用[D]. 中国科学院研究生院,2018.
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