Incorporation of 1-ethyl-3-methyl-imidazolium acetate into UiO-66 as an efficient sorbent for carbon dioxide capture

Adjusting the internal porous environment of MOFs to enhance their adsorption properties is considered an effective strategy to improve their gas separation performance. Herein, 1-ethyl-3-methyl-imidazolium acetate ([Emim][Ac]) was encapsulated in UiO-66 by an impregnation method for the improvement of carbon dioxide (CO2) capture performance. The synthesis and detailed characterizations of the developed [Emim][Ac]@UiO-66 are reported, and the effect of the loading amount of [Emim][Ac] on the CO2 separation performance was also studied. The obtained [Emim][Ac]@UiO-66 could efficiently show the synergistic effect of the adsorption of CO2 between [Emim][Ac] and UiO-66. The optimized [Emim][Ac]@UiO-66 exhibited a much higher CO2 adsorption capacity at 298 K and 1.0 bar, affording 2 times the CO2 uptake than its original UiO-66. In addition, the CO2/N2 selectivity and CO2/CH4 selectivity of [Emim][Ac]@UiO-66-3.5% are significantly higher than those of UiO-66. This study for designing various MOF-encapsulated ionic liquids potentially paves the way for the development of highly efficient absorbents for gas separations.