离子液体分离含低碳醇共沸物的液液相平衡与模拟
发布时间：2018-10-16 16:32
【摘要】：离子液体作为新型绿色溶剂具有可设计性、宽液程和不挥发性等独特理化性质,可作为传统有机溶剂的优良替代品。离子液体的理论研究是实践应用的前提,而离子液体的基础物性数据对理论研究至关重要。本文应用量子化学方法对离子液体的分子结构体积参数r和表面积参数q进行了计算。利用限制性哈特里-福克方法以及密度泛函理论优化了离子液体的分子结构,然后采用极化连续介质模型计算最优分子结构参数r和q值,进而得到12种离子液体分子结构参数。使用UNIQUAC模型结合分子结构参数关联了文献中含离子液体体系液液相平衡实验数据,得到了相应的体系UNIQUAC模型参数,计算得到均方根偏差平均值为0.0117,表明计算的离子液体r和q值用于UNIQUAC模型能较好的关联三元体系液液相平衡数据。针对目前工业生产中含低碳醇共沸物难分离的问题,本文采用咪唑类离子液体作为萃取剂进行了液液相平衡实验来探究离子液体对含低碳醇共沸物萃取的可行性。针对低碳醇-水共沸体系,采用1-烷基-3-甲基咪唑双三氟甲磺酰亚胺盐([Cnmim][NTf2])为萃取剂,研究了三种水-低碳醇-[Cnmim][NTf2]体系的液液相平衡。针对低碳醇-正庚烷共沸体系,采用[Hmim][OTf]作为萃取剂,研究了三种正庚烷-低碳醇-[Hmim][OTf]体系的液液相平衡。测定了相应的液液相平衡实验数据并计算出分配比和分离因子,评估了离子液体的萃取能力并与文献中的离子液体萃取能力进行了对比。本文进一步探究了咪唑类离子液体的烷基链取代基长度和醇的结构在体系液液相平衡中的规律。结合计算的离子液体的结构参数r和q值,利用NRTL和UNIQUAC模型关联了本文中六组含离子液体的液液相平衡实验数据,得到NRTL和UNIQUAC模型参数。利用UNIFAC模型预测了正庚烷-低碳醇-[Hmim][OTf]的相行为,与实验结果进行了比较,评估了UNIFAC模型对含离子液体体系的预测能力。实验结果表明了本文所用的离子液体分离含低碳醇共沸物的可行性。计算得到的离子液体结构参数、含离子液体体系实验数据和热力学模型参数,可用于该类体系的液液相平衡计算及相关过程的设计。
[Abstract]:As a new green solvent, ionic liquids have unique physicochemical properties, such as designability, wide liquid range and no volatility, so they can be used as excellent substitutes for traditional organic solvents. The theoretical study of ionic liquids is the premise of practical application, and the basic physical properties of ionic liquids are very important to the theoretical research. In this paper, quantum chemical method is used to calculate the molecular structure volume parameter r and surface area parameter Q of ionic liquids. The molecular structure of ionic liquids was optimized by using restricted Hartley-Focker method and density functional theory, and the optimum molecular structure parameters r and Q were calculated by polarization continuum model. The molecular structure parameters of 12 kinds of ionic liquids were obtained. The experimental data of liquid-liquid equilibrium of ionic liquids in literature were correlated with the UNIQUAC model and the molecular structure parameters, and the corresponding UNIQUAC model parameters were obtained. The average RMS deviation is 0.0117, which indicates that the calculated values of r and Q of ionic liquids can well correlate the liquid-liquid equilibrium data of ternary system with UNIQUAC model. Aiming at the difficult separation of azeotropic compounds containing low carbon alcohols in industrial production, the liquid-liquid equilibrium experiments were carried out with imidazole ionic liquids as extractants to explore the feasibility of extraction of azeotropic compounds containing low carbon alcohols by ionic liquids. In this paper, the liquid-liquid equilibrium of three kinds of water-low alcohol [Cnmim] [NTf2] system was studied by using [Cnmim] [NTf2] as extractant for low carbon alcohol-water azeotropic system. The liquid-liquid equilibrium of n-heptane-n-heptane azeotropic system was studied by using [Hmim] [OTf] as extractant. The liquid-liquid equilibrium of three kinds of n-heptane-low alcohol [Hmim] [OTf] system was studied. The experimental data of liquid-liquid equilibrium were measured and the partition ratio and separation factor were calculated. The extraction ability of ionic liquid was evaluated and compared with that in literature. The length of alkyl chain substituents and the structure of alcohols in the liquid-liquid equilibrium of imidazole ionic liquids were further investigated. Combined with the calculated structural parameters r and Q of ionic liquids, the NRTL and UNIQUAC models were used to correlate the experimental data of liquid and liquid equilibrium of six groups of ionic liquids, and the parameters of NRTL and UNIQUAC models were obtained. The phase behavior of n-heptane-low-carbon alcohol- [Hmim] [OTf] was predicted by UNIFAC model, and compared with the experimental results. The prediction ability of UNIFAC model for ionic liquid system was evaluated. The experimental results show that the ionic liquid used in this paper is feasible for the separation of azeotrope containing low carbon alcohols. The calculated structure parameters, experimental data and thermodynamic model parameters of ionic liquids can be used to calculate liquid-liquid equilibrium and design related processes.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O645.1;O642.42
本文编号：2274979
[Abstract]:As a new green solvent, ionic liquids have unique physicochemical properties, such as designability, wide liquid range and no volatility, so they can be used as excellent substitutes for traditional organic solvents. The theoretical study of ionic liquids is the premise of practical application, and the basic physical properties of ionic liquids are very important to the theoretical research. In this paper, quantum chemical method is used to calculate the molecular structure volume parameter r and surface area parameter Q of ionic liquids. The molecular structure of ionic liquids was optimized by using restricted Hartley-Focker method and density functional theory, and the optimum molecular structure parameters r and Q were calculated by polarization continuum model. The molecular structure parameters of 12 kinds of ionic liquids were obtained. The experimental data of liquid-liquid equilibrium of ionic liquids in literature were correlated with the UNIQUAC model and the molecular structure parameters, and the corresponding UNIQUAC model parameters were obtained. The average RMS deviation is 0.0117, which indicates that the calculated values of r and Q of ionic liquids can well correlate the liquid-liquid equilibrium data of ternary system with UNIQUAC model. Aiming at the difficult separation of azeotropic compounds containing low carbon alcohols in industrial production, the liquid-liquid equilibrium experiments were carried out with imidazole ionic liquids as extractants to explore the feasibility of extraction of azeotropic compounds containing low carbon alcohols by ionic liquids. In this paper, the liquid-liquid equilibrium of three kinds of water-low alcohol [Cnmim] [NTf2] system was studied by using [Cnmim] [NTf2] as extractant for low carbon alcohol-water azeotropic system. The liquid-liquid equilibrium of n-heptane-n-heptane azeotropic system was studied by using [Hmim] [OTf] as extractant. The liquid-liquid equilibrium of three kinds of n-heptane-low alcohol [Hmim] [OTf] system was studied. The experimental data of liquid-liquid equilibrium were measured and the partition ratio and separation factor were calculated. The extraction ability of ionic liquid was evaluated and compared with that in literature. The length of alkyl chain substituents and the structure of alcohols in the liquid-liquid equilibrium of imidazole ionic liquids were further investigated. Combined with the calculated structural parameters r and Q of ionic liquids, the NRTL and UNIQUAC models were used to correlate the experimental data of liquid and liquid equilibrium of six groups of ionic liquids, and the parameters of NRTL and UNIQUAC models were obtained. The phase behavior of n-heptane-low-carbon alcohol- [Hmim] [OTf] was predicted by UNIFAC model, and compared with the experimental results. The prediction ability of UNIFAC model for ionic liquid system was evaluated. The experimental results show that the ionic liquid used in this paper is feasible for the separation of azeotrope containing low carbon alcohols. The calculated structure parameters, experimental data and thermodynamic model parameters of ionic liquids can be used to calculate liquid-liquid equilibrium and design related processes.
【学位授予单位】：青岛科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O645.1;O642.42
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