Inverse Gas Chromatography as a Screening Technique for Henry's Law Constants of Gases in Ionic Liquids

Henry's law constants of various gases in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim]-[Tf2N]), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]), 1-allyl-3- methylimidazolium bis(trifluoromethylsulfonyl)imide ([allylmim][Tf2N]), and 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]) were measured using an inverse gas chromatography (GC) method. The gases explored were carbon dioxide, ethane, ethylene, propane, and propylene at temperatures ranging from 298.15 to 373.15 K. The temperature dependence of the Henry's law constants was used to determine the standard enthalpies of absorption of the gases in the ionic liquids (ILs). Comparison of our measured values of Henry's law constants and enthalpies with the literature leads to the conclusion that the GC method is a fast technique for screening ILs for various gas separation applications.