• Open Access

Screening ionic liquids as candidates for separation of acid gases: Solubility of hydrogen sulfide, methane, and ethane


Correspondence concerning this article should be addressed to R. A. Marriott at rob.marriott@ucalgary.ca.


The solubility of the major constituents of natural gas in ionic liquids (ILs) can be used to identify their potential for acid gas removal from a producing gas stream. We have developed models for the solubility of H2S, CH4, and C2H6 in ILs at typical conditions encountered in natural gas treatment. In this work, a conductor-like screening model for realistic solvation was used to predict the activity coefficients for solutes in ILs and a cubic EOS was used for vapor-phase corrections from ideality. Empirical correlations were developed to extrapolate solubilities where experimental data are not available at desired conditions; targeted in this study at 298.15 K and 2000 kPa. Over 400 possible ILs were ranked based on the higher selectivity of absorption of CO2 and H2S over CH4 and C2H6. The best 15% (58) of promising ILs for sour gas treatment predominantly contain the anions BF4, NO3, and CH3SO4 and the cations N4111, pmg, and tmg. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2993–3005, 2013