Modelling carbon dioxide solubility in ionic liquids

Abstract

Abstract Solubility information for CO 2 in different ionic liquids, ILs, in part can potentially be used to select a specific IL for the separation of CO 2 from hydrocarbon fluids. Unfortunately, not all CO 2 –IL systems have been experimentally described at similar temperatures and pressures; therefore, a direct comparison of performance by process simulation is not always possible. In the extreme cases, the design of a CO 2 separation process may require predicting the CO 2 –IL equilibria for which there are no available solubility data. To address the need for this information, a semi‐empirical correlation was developed to estimate the dissolution of CO 2 in CO 2 –IL solvent systems. The theoretical COSMO–RS calculation method was used to calculate the chemical potential of CO 2 in a wide variety of ILs and the Soave–Redlich–Kwong equation was used to calculate the fugacity coefficient of the CO 2 vapour phase. The model was correlated with available literature data, yielding an average error of AAR = 23% and small bias. © 2012 Canadian Society for Chemical Engineering