Solvent absorption is currently the main decarbonization method, in which propylene carbonate (PC) washing is widely applied in virtue of its low material loss and simple process. In regard of the low solubility and selectivity to CO2 of PC, traditional PC washing process is improved by adding 2- methylimidazole (2-mIm) and water as additives to PC. In this paper, firstly the miscible point of 2-mIm-waterPC three phase system as well as saturation point of 2- mIm were measured, so was the viscosity of mixture solvent. Next, the solubility of CO2 in mixture solvents with different proportion was measured to make a comparison with that in pure PC, where temperature was in 298.15 and 308.15 K, pressure was in the range of 0.01-1.40 MPa. The heats of CO2 absorption in these solvent mixtures were calculated using the ClausiusClapeyron equation. Then the kinetic curves of pure PC and mixture solvents were measured, and solvent 2 (2- mIm 16.7 wt% + water 8.3 wt% + PC 75 wt%) showed an comparable absorption rate to that of pure PC and absorption balance can be achieved in a short time. Experimental results show that the mixture solvent possesses outstanding carbon capture capacity and is feasible to be applied in current PC washing process without any demand of equipment modification.
Keywords CO2 capture, PC washing process, absorption isotherm, absorption heat.