Theoretical and Experimental Study of CO2 Absorption by N-2-ethylhexylethylenediaminium-TFS Type Protic Ionic Liquid

Abstract The CO 2 absorption using the mixture of ethylenediaminium type protic ionic liquid [HEtHexen][TFS] and H 2 O with different molar ratio was investigated by the measurement of pH, density, viscosity and conductivity at 30°C. Meanwhile, we studied the hydrogen bonding between [HEtHexen][TFS] and CO 2 using DFT calculation, the result of the interaction energy, vibration frequency and second-order perturbation energy, etc. shows that a weak or medium strength N-H···O type hydrogen bonding occurred between [HEtHexen][TFS] and n CO 2 ( n =1−4). The result of experimental and theoretical study indicates that one [HEtHexen][TFS] molecule absorbed a maximum of three molecules of CO 2 .