Solid Supported [hmim][Tf<sub>2</sub>N] for CO<sub>2</sub> Adsorption

Abstract

Ionic liquids are new alternative solvents that can be used to separate carbon dioxide in the gas separation process. However, the high viscosity of ionic liquids limits the mass transfer of solutes into ionic liquids. In this work, 1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([hmi [Tf2) was impregnated onto porous Al2O3 and SiO2 and tested for CO2 adsorption at pressure up to 40 bar at 25 °C. The screening process showed that [hmi [Tf2-Si gave higher CO2 adsorption capacity compared to [hmi [Tf2-Al and pure [hmi [Tf2. The experimental work was further investigated by varying the composition of [hmi [Tf2 inside SiO2 pores. The composition of [hmi [Tf2 was varied from 10 wt% to 40 wt%. The result showed the 10 wt% composition gave the highest CO2 adsorption compared to 20 wt%, 30 wt% and 40 wt%. The lower CO2 adsorption by 20 wt%, 30 wt% and 40 wt% might be due to the blockage of SiO2 pores by excess [hmi [Tf2. From this research, it proved that porous solid support can provide high surface area that is necessary to accommodate intimate contact between CO2 and solid supported ionic liquid and increases the CO2 adsorption capacity.