Novel Fluid Ionic Liquid Composites with Self-Assembled Porosity and Chemical Sites for Facilitating CO2 Separation

Porous ionic liquid (IL) composites, such as impregnated, encapsulated, and porous ILs, are widely used for CO2 capture. However, IL-based adsorbents generally have relatively low IL loading, which cannot fully exploit the unique advantages of ILs. Porous ILs with high IL loading over 90 wt % had high viscosity affecting mass transfer. Therefore, how to simultaneously avoid high viscosity and improve the CO2 absorption rate and IL loadings is of great significant. Herein, a novel fluid IL composite with self-assembled porosity and chemical sites was originally proposed for the CO2 separation. It was prepared by introducing amino-acid IL (AAIL) [N2222][Gly] as the dispersing phase, the mixture of [Emim][Tf2N] (IL1) and [HDBU][Im] (IL2) as the continuous phase, and silica H-20 as the emulsifier, which was named AAIL-H20-IL1/IL2. The results demonstrated that an excellent CO2 capacity of 2.30 mmolCO2/g-sorbent was obtained (313 K/1 bar) with the highest IL loading of 98 wt % among the state-of-the-art value. Meanwhile, micro droplets and porous structures can effectively increase the CO2 absorption rate. The superior CO2 capacity was deduced by the chemisorption of [N2222][Gly] and [HDBU][Im] revealed by in situ FTIR and DFT calculation. In general, this work proposes a pioneer strategy to prepare fluid porous IL composites with ultrahigh IL loading for facilitating CO2 separation.