Highly efficient and reversible H2S capture by mercapto carboxylic anion functionalized ionic liquids

Four mercapto carboxylic anion functionalized ionic liquids (MCA-ILs) were designed and applied in H2S uptake. The solubility of H2S in MCA-ILs aqueous solution was measured from 303.2 to 333.2 K and pressure up to 1.0 bar. The reaction equilibrium thermodynamic model (RETM) was applied to fit the experimental data. Impressively, it was found that mercapto carboxylic anion captured H2S through 1:1 and 2:1 M ratio manner, which was supported by the results of RETM and quantum chemistry calculations. Furthermore, the solubility of H2S in 95% [P-4444][MSA] could reach up to 0.9 mol/mol ILs and the enthalpy of the reaction was low (-22.21 kJ/mol). Considering the high H2S absorption capacity and low energy consumption of desorption, we believe that MCA-ILs solutions could provide an attractive alternative to be used as absorbent in H2S uptake. (C) 2021 Elsevier B.V. All rights reserved.