含CO_2/离子液体系统相行为及其在反应与分离中的应用进展

CO_2/Ionic Liquids Phase Behaviors and Its Applications for Reaction and Separation

目前已知的绿色溶剂主要包括超临界流体(supercritical fluids,SCFs)、离子液体(ionic liquids,ILs)、二氧化碳膨胀液体(CO2expanded liquids,CXLs)、水以及上述溶剂的混合物等。其中,由超临界CO2(supercritical CO2,SCCO2)与IL混合而构成的新型溶剂,因为化学热力学方面的特性,成为近年来研究的热点,未来很有发展前景。本文回顾了目前为止在该领域所开展的工作,总结了影响SCCO2与ILs相行为的主要因素,包括温度、压力I、Ls的含水量I、Ls的阴离子I、Ls的阳离子I、Ls的摩尔体积以及助溶剂等。同时分析了ILs/SCCO2与溶质形成的多元混合物相行为的成因。介绍了ILs/CO2在萃取、反萃取、膜分离、反胶束、萃取与反应耦合等方面的应用。由于传统的单元操作很难满足无污染和对过程集成的要求,因而含有ILs/SCCO2的分离反应耦合过程将是未来实现清洁生产的发展方向。

It is known that supercritical fluids （SCFs）, room-temperature ionic liquids （ILs）, CO2 liquids （CXLs）, water, as well as their mixtures are currently expanded regarded as green solvents. Among them, the mixtures of SCFs and ILs have received considerable research attention due to their favorable thermodynamic properties. This review summarizes the recent progress in this filed, focusing on the factors that influence the phase behavior of SCFs and ILs, such as pressure, temperature, water contents, molar volume of ILs, co-solvents, anions, and cations. In addition, the phase behavior of the muhicomponent systems containing the coupling solvent ILs/SCCO2 and the solute is also analyzed. Finally, the potential applications of ILs/SCCO2 coupling solvent are proposed, including extraction, anti-extraction, membrane separation, reverse micelle, and separation coupling with reaction. In particular, coupling separation with reaction using SCCO2/ILs as the green solvent will be one of the ways of clean production.