Insight into the role of ionic liquid for improving silica aerogel performance in CO2 adsorption

To improve the CO2 adsorption properties of silica aerogels, [BMIM][PF6]/silica aerogels were prepared by a one-step sol-gel process. The improvement of the ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM][PF6]) on the aerogel structure and CO2 adsorption properties were analyzed by experiments combined with saturated adsorption simulation. The infrared spectroscopy, scanning electron microscopy, and Brunner-Emmet-Teller (BET) analysis results show that [BMIM][PF6] is evenly dispersed in an aerogel structure, which leads to a more evenly distributed pore size distribution for the aerogels. The adsorption thermodynamics of the Clausius-Clapeyron equation shows that the adsorption of CO2 on the composite aerogel is mainly physical adsorption, and the CO2/N2 selectivity of the adsorbent at 298 K and 1 bar was calculated to be 24.7 using the ideal solution model. Composite aerogels are an ideal material for separating CO2 from the air.