Experimental and computational studies on the solubility of carbon dioxide in protic ammonium-based ionic liquids

The solubility data of carbon dioxide (CO2) in the new synthesized protic ionic liquids (PILs), diisopropylethy-lammonium propanoate [DIPEA][C2COO] and diisopropylethylammonium butanoate [DIPEA][C3COO] have been measured at temperatures range from 303.2 K to 348.2 K and pressures up to 7.04 MPa with a synthetic method. The solubility of CO2 in [DIPEA][C2COO] are found to be much higher than that of [DIPEA][C3COO], about three folds, under the same temperature and pressure. The solubility data of CO2 + [DIPEA][C2COO] were correlated by using the Peng-Robinson equation of state with the temperature-dependent two-parameter van der Waals one-fluid mixing rules. Moreover, the interactions among CO2 and the PIL ions were explored by molecular dynamics (MD) simulation at ambient conditions. The effect of the dissolved CO2 in the PILs on the intermolecular hydrogen bonds between the ammonium hydrogen of the PIL cation and carboxylate oxygen of the anion was also investigated. (C) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.