Solubilities of gases in ionic liquids and its applications to separation processes

Abstract

In the present paper, gas solubilities in ionic liquids (ILs) have extensively been reviewed in terms of physical and chemical absorption capabilities. The phase behaviors and volume expansivities were compared between IL-CO2 and molecular liquid-CO2 systems. The effects of anion and cation structures on the physical solubilities of CO2 were described, and the dissolution mechanism was discussed on the basis of the thermodynamic parameters with the related spectroscopic and simulation results. The chemical absorption properties of ILs were also summarized in several types, i.e., the cation- and anion-functionalized ILs, hybrid ILs, and the others. Using the above-mentioned ILs, three different types of gas separation processes, the high-pressure physical absorption, temperatureswing chemical absorption, and vacuum-swing absorption techniques, have been surveyed with their strong advantages over conventional processes.