Experimental and modelling study of CO2 absorption in ionic liquids containing Zn (II) ions

This paper studies an ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl) imide ([EMIM][TFSI]) containing Zn2+ ions as a novel functional group for CO2 absorption. Their physical properties including the density, decomposition temperature, phase transition temperature, heat capacity and viscosity have been characterised. The CO2 solubility measurements have been carried out under constant pressures of 0.1, 0.3, 0.5, 0.7 and 1.0 bar at 40 °C. The result shows an appealing solubility of 8.2 wt% CO2 at 1.0 bar. The real-time absorption kinetics was studied using a comprehensive diffusion model for a reacting system. Based on this model, the corresponding diffusion coefficients and the reaction rate constant have been obtained. The diffusion and reaction behavior of CO2 in the physical/chemical absorption has also been discussed.