1H NMR化学位移预测离子液体溶液体系的汽液平衡性质

Vapor-liquid equilibria (VLE) property of mixtures containing ionic liquid (IL) is of vital importance in the process of extraction distillation and solution thermodynamics. The prediction of VLE property of mixtures containing IL is highly desirable, especially when VLE data are difficult to measure, or the measurement is not economical. The research work of the prediction of VLE can also provide theoretical guidance for extraction distillation. Because the energy parameters of mixtures containing IL are difficult to obtain through the traditional thermodynamics methods, the relevant research work of the prediction of VLE property is still lacking. Therefore, in this work, a new method is developed to predict VLE property of mixtures containing IL by using the energy parameters obtained from 1H NMR chemical shifts. The process of researching is as follows: Firstly, the energy parameters of binary mixtures containing IL are obtained by correlation of the concentration-dependent 1H NMR chemical shifts of IL and solvent using local composition model. Secondly, the VLE property of binary and ternary mixtures containing IL are predicted through the energy parameters and coupled with the activity coefficient models, respectively. Thus, the quantitative relationship between 1H NMR chemical shifts and VLE property of mixtures containing IL is established. On the basis of the above research achievement, a systematic analysis of the influence of concentration and structure of IL on the relative volatility of azeotropic mixtures and the azeotrope breaking capacity is carried out, which is used to establishment of theoretical guidelines for selecting the most suitable IL for the separation of specific azeotropic mixtures. This study will also promote the development of spectroscopic technologies on the thermodynamic property and microstructure of mixtures containing IL.

离子液体溶液体系的汽液平衡性质与萃取精馏过程紧密相关，也是溶液热力学的重要研究内容。理论预测离子液体溶液体系的汽液平衡具有十分重要的研究意义，这不仅可以估算离子液体溶液体系某些不易测定或紧缺的汽液平衡数据，而且可为离子液体在萃取精馏领域的应用提供理论指导。本项目针对传统热力学方法难以获得预测离子液体溶液体系汽液平衡所需能量参数的问题，拟采用1H NMR化学位移结合局部组成模型获得离子液体+溶剂二元体系的相互作用能量参数，并结合活度系数模型预测离子液体+溶剂二元体系、离子液体+溶剂1+溶剂2三元体系的汽液平衡性质，建立离子液体溶液体系1H NMR化学位移和汽液平衡性质的定量关系。在此基础上, 采用1H NMR手段研究离子液体浓度、阳离子链长和阴离子种类对二元共沸体系相对挥发度的影响，揭示离子液体改变共沸体系汽液平衡性质的内在原因，并拓展谱学手段在研究离子液体溶液热力学性质和微观结构中的应用。

离子液体作为一种新兴的萃取精馏剂，在分离共沸体系方面表现出了优良的性能和广阔的应用前景。但目前有关理论预测离子液体溶液体系汽液平衡性质的基础研究却相对较少。为此，本项目首先采用1H NMR和IR等谱学手段、物性实验和局部组成模型，定性地研究了离子液体与水、醇、乙腈、DMSO等溶剂的相互作用及其对乙酸乙酯-乙醇、乙腈-水、乙醇-水等共沸体系微观结构以及相对挥发度的影响；在定性研究的基础上，采用1H NMR化学位移和局部组成模型获得了烷基咪唑离子液体-溶剂(水、乙醇、乙腈等)二元体系的相互作用能量参数，定量预测了烷基咪唑离子液体-水、烷基咪唑离子液体-乙醇等二元体系的汽液平衡性质，并预测了离子液体-乙醇-水和离子液体-乙腈-水等三元体系的汽液平衡性质，成功建立了离子液体溶液体系1H NMR化学位移与汽液平衡的定量关系；最后，采用1H NMR、COSMO-RS模型和汽液平衡实验，讨论了烷基咪唑离子液体浓度、阳离子链长和阴离子种类对共沸体系微观结构和汽液平衡性质的影响，揭示离子液体改变二元共沸体系汽液平衡的内在原因，发现烷基咪唑离子液体阳离子C2-H在改变共沸体系汽液平衡方面发挥着重要的作用。在本项目的资助下，共发表相关SCI论文14篇，申请发明专利4项(授权3项)，会议论文6篇(邀请报告2篇)，培养硕士研究生2人(在读)。