LAUSR

Abstract Post-combustion CO 2 capture requires the focus on improvement of absorbent formulations and process efficiency to capture CO 2 from flue gas streams in the plants. The present work was aimed to a comparative study of CO 2 absorption capacity into 1-Ethyl-3-methylimidazolium acetate ([Emim][Ac]) ionic liquid (IL) and both the aqueous solutions of activated N -methyldiethanolamine (MDEA) with 3.8 wt.% piperazine (PZ) and promoted potassium carbonate with 2.5 wt.% diethanolamine (DEA) in a bench scale packed bed column. The CO 2 absorption tests were conducted at pressure of 4 bar and temperatures of 343.15–353.15 K. The inlet gas mixture has a typical composition of post-combustion processes consisting of 7.0% (v/v) CO 2 diluted with N 2 . The influence of temperature and gas and liquid flow directions on the CO 2 absorption at constant pressure and inlet CO 2 concentration were examined. The results showed that the aqueous activated 38.7 wt.% MDEA solution has the highest overall mass transfer coefficient followed by the aqueous 28 wt.% promoted K 2 CO 3 solution, while the [Emim][Ac] solvent showed the least overall mass transfer coefficient. The [Emim][Ac] indicated enhancement by chemical absorption, giving a value higher than 44 for enhancement factor. Additionally, as temperature raised from 343.15 to 353.15 K, only small decrease in overall mass transfer coefficients of both aqueous solutions was observed, while in the case of [Emim][Ac] IL, the overall mass transfer coefficient increased significantly. It was also found that the cocurrent flow of gas and liquid for all the absorbents takes more absorption time than the countercurrent flow case. The liquid side mass transfer coefficient of the IL was lower than both the traditional activated absorbents. This can be attributed to significant impact of the IL viscosity as an important factor on mass transfer flux. At 353.15 K and 4 bar, the studied IL showed 29% more CO 2 absorption capacity than activated MDEA solution and 16% more than promoted K 2 CO 3 solution. Based on this study, the investigated solvents showed promising capability for removal of CO 2 from post combustion flue gases emitted in industrial plants.