Absorption Behavior of Acid Gases in Protic Ionic Liquid/Alkanolamine Binary Mixtures

Herein, we studied the absorption of H2S and CO2 by alkanolamine–protic ionic liquids binary mixtures based on 2-hydroxyethylammonium (MEA) or triethanolammonium cations and residues of 2-hydroxy-5-sulfobenzoic acid or pyridine-3-carboxylic acid at various temperatures and partial gases pressures. It was found that absorbents based on the 2-hydroxyethylammonium cation, performed high absorption properties toward the H2S. The solubility of hydrogen sulfide, characterized by the Henry's Law constant, in MEA-based binary mixtures had the values comparable to the commercially available ionic liquids. The results of thermal desorption analysis demonstrated that the capture of acid gases in MEA-based absorbents occurred at two stages: through the dissolution in MEA component and in protic ionic liquid.