The influence of water content in imidazolium based ILs on carbon dioxide removal efficiency

The study of CO2 absorption in ionic liquids: [Emim] [Ac], [Bmim] [Ac] and 15 wt.% MEA solution in bubble reactor and packed bed column is presented. Bubble glass reactor with a capacity of 2 dm3 and absorption column of inner diameter 0.05 m and 0.3 m length filled with Raschig rings ϕ5 × 5 × 1 mm were used. The influence of absorption temperature and water content in ILs on CO2 removal efficiency was investigated at atmospheric pressure what is important in the case of post combustion flue gases. In calculations the resistance in series model of the absorption process was applied. The estimated values of enhancement factor of the reaction between CO2 and investigated liquids were used to predict mass fluxes of absorbed carbon dioxide for ILs with water content 2-10 wt.%. The comparison of experimental and calculation results show that in the same experimental conditions investigated ILs and MEA solution have comparable CO2 absorption capacities while mass transfer coefficients in the case of ILs are significantly lower than for MEA solution. The small content of water in IL (2-5 wt.%), inevitable in continuous cyclic use of IL in industrial conditions, may be profitable in reducing high viscosity of ILs and increasing mass transfer rate.