Prediction of Ionic Liquids Performance for Hydrogen Sulfide Absorption from Natural Gas using COSMO-RS

Abstract

The capability of ionic liquids (ILs) in various applications makes them attracted by many researchers. They have potential to be developed as “green” solvents for gas separation, especially hydrogen sulfide (H 2S) gas. In this work, it is attempted to predict the solubility of H 2S in ILs by COSMO-RS method. Since H 2S is a toxic pollutant, it is difficult to handle in the laboratory, therefore an appropriate model will be necessary in prior work. The COSMO-RS method is implemented to predict the Henry’s law constants and activity coefficient of H 2S in 140 ILs with various combinations of cations and anions. It is found by the screening that more H 2S can be absorbed in ILs with chloride ([Cl]-) and acetate ([Ac]-) anion. The solubility of H 2S in ILs with different alkyl chain at the cations not much affected and with different type of cations are slightly influence H 2S capture capacities. Even though the cations do not affect much in solubility of H 2S, the effectiveness of cation still need to be considered in different way. The prediction results only show their physical absorption ability, but the absorption of H 2S need to be consider chemically to get high capacity of absorption of H 2S.