UNIFAC Model for Ionic Liquid-CO (H2) Systems: An Experimental and Modeling Study on Gas Solubility

The universal quasichemical functional-group activity coefficients (UNIFAC) model for ionic liquids (ILs) has become notably popular because of its simplicity and availability via modern process simulation softwares. In this work, new group binary interaction parameters ((mn) and (nm)) between CO (H-2) and IL groups were obtained by correlating the solubility data in pure ILs at high temperatures (above 273.2 K) collected from the literature. the solubility of CO in [BMIM](+)[BF4](-), [OMIM](+)[BF4](-), [OMIM](+)[Tf2N](-), and their mixtures, as well as that of H-2 in [EMIM](+)[BF4](-), [BMIM](+)[BF4](-), [OMIM](+)[Tf2N](-), and their mixtures, at temperatures from 243.2 to 333.2 K and pressures up to 6.0 MPa were measured. The UNIFAC model was observed to well predict the solubility in pure and mixed ILs at both high (above 273.2 K) and low (below 273.2 K) temperatures. Moreover, the selectivity of CO (or H-2) to CO2 in ILs increases with decreasing temperature, indicating that low temperatures favor for gas separation. (c) 2014 American Institute of Chemical Engineers AIChE J 60: 4222-4231, 2014