离子液体-低碳醇-水体系的液液相行为及热力学模拟

The types and the combinations form the anion and cation constituting ionic liquids (ILs), and the substituent group types of cationic branched chain, molecular structure and the carbon chain length and so on are planed to be considered to solve the difficulties of the separation of lower alcohols and water in biomass fermentation. The phase behaviors for the system of typical ILs + lower alcohols + water at different temperatures are investigated systematically to determine the influence factors of ILs on the liquid-liquid equilibrium (LLE) of the system consisting of lower alcohols and water, and get the influence mechanisms. The research about the separation of aqueous biomass fermentation including lower alcohols based on ILs used as extraction agent can lay the foundation for the efficient utilization of biomass energy containing lower alcohols such as ethanol, butanol, amyl alcohol and so on. The molecular connectivity index is introduced into the thermodynamic modeling for the ternary system containing ILs based on the ternary LLE experimental binodal curve. Moreover, the change rule of binary interaction parameters for ILs and alcohol, ILs and water in ternary system at different temperature is explored. The extended NRTL, UNIQUAC and UNIFAC model are developed on the basis of the stable interaction parameters, which can be used to calculate the LLE for system composed of ILs, alcohol and water.

针对生物质发酵液中低碳醇与水分离困难的问题，拟从构成离子液体（ILs）的阴阳离子种类、阴阳离子组合方式、阳离子支链取代基类型、分子结构、碳链长度等角度出发，系统考察典型ILs-低碳醇-水体系在不同温度下的相行为，确定ILs对低碳醇-水体系液液平衡（LLE）的影响因素并得到影响机理，研究基于ILs作为萃取剂的低碳醇水生物质发酵液体系的分离，为含乙醇、丁醇、戊醇等低碳醇类生物质能源的高效利用奠定基础。基于三元LLE实验双结点曲线，将分子连接性指数引入到含ILs三元体系的热力学模拟中，探究不同温度下，三元体系中ILs与醇及水的二元交互作用参数的变化规律，在稳健型的交互作用参数的基础上，发展可用于含ILs的醇水体系液液平衡计算的扩展NRTL、UNIQUAC、UNIFAC模型。

液液萃取在沸点相近混合物、高沸点混合物、热敏性混合物以及共沸混合物等混合物的分离中具有重要的地位，广泛应用于化工、制药等行业。项目针对含低碳醇的共沸体系考察了离子液体作为萃取剂时的三元液液相行为，并采用NRTL、UNIQUAC、UNIFAC、热力学模型进行了热力学模拟，设计并优化了相关物系的分离，主要内容包括：（1）测定了16个体系100多个数据点的离子液体-低碳醇-水体系的液液平衡数据，根据分配系数和选择性判定离子液体作为萃取剂的适用性;（2）采用密度泛函理论优化离子液体的分子结构，得到离子液体的最优结构和最优能，然后采用极化连续介质模型计算最优分子结构的体积和表面积，进而得到离子液体的分子结构参数r和q;（3）基于NRTL、UNIQUAC模型对实验数据进行关联，得到了40多组二元交互作用参数，用UNIFAC模型预测液液平衡数据，得到阳离子烷基链长度及阴离子对相行为影响的规律;（4）扩展研究了低碳醇-ILs-酯和低碳醇-ILs-烷烃的液液平衡，并对分离工艺进行过程模拟;（5）扩展研究了共沸体系的特殊分离方法。项目的研究结果丰富完善了离子液体-含低碳醇共沸体系基础热力学数据，对模型化方面的理论及工业分离过程的设计与优化具有促进作用。