Influence of the interaction between hydrogen sulfide and ionic liquids on solubility: Experimental and theoretical investigation

The solubility of H S in a series of 1-butyl-3-methylimidazolium ([bmim](+)) based ionic liquids (ILs) with different anions, chloride, tetrafluoroborate ([BF4](-)), hexafluorophosphate ([PF6](-)), triflate ([TfO](-)), and bis(trifluoromethyl)sulfonylimide ([Tf2N](-)), and in a series of [Tf2N] ILs with different cations, i.e., N-alky-N '-methylimidazolium, 2-methyl-N-methyl-N'-alkyimidazolium, N-alkylpyridinium, N-butyl-N-methylpyrrolidinium, and N-alkyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium has been determined using medium-pressure NMR spectroscopy. The observed solubilities are significantly higher than those reported for many other gases in ILs, suggesting the occurrence of specific interactions between H2S and the examined ILs. Quantum chemical calculations have been used to investigate at a molecular level the interaction between H2S and the [bmim](+)-based ILs.