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

Abstract

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.