A new approach to the upgrading of the traditional propylene carbonate washing process with significantly higher CO2 absorption capacity and selectivity

•The traditional PC washing approach was improved by adding mIm to PC with the presence of EG as cosolvent.•CO2 solubility increases rapidly while those of CH4, N2 and H2 decrease drastically in the presence of mIm.•Viscosity and absorption heat could remain on low level for EG-mIm-PC complex solvents.•The selectivity of CO2 over CH4, N2 and H2 could be increased significantly using EG-mIm-PC complex solvents.