# Ionic Liquids Hybridization for Carbon Dioxide Capture: A Review
## 4 Application of ILs Hybrid Material in Carbon Dioxide
### ILs/Mesoporous Silica
In the meantime, to overcome the high cost and tedious procedure of task-specific ILs synthesis, [PERSON] et al. decided to impregnate the mesoporous SBA-15 with PILs, [TEPA][NO\({}_{3}\)] [98]. In their work, the hybrid porous material was prepared by adding 1.0 g of SBA-15 into an ethanol solution containing a designated amount of [TEPA][NO\({}_{3}\)]. The mixture was stirred for 6 h at room temperature. Residue was collected after removing ethanol and further dried under in a vacuum at 100 \({}^{\circ}\)C for 12 h. The reduction in the pores' surface area and diameter of hybrid S15/[TEPA][NO\({}_{3}\)] indicates pore filling by [TEPA][NO\({}_{3}\)]. Crystal phase analysis showed the presence of fraction peaks which correspond to crystallographic planes of SBA-15. As the [TEPA][NO\({}_{3}\)] loading exceeded 50%, the intensity of fraction peak substantially reduced due to a decrease in the 2D hexagonal structure. A large deviation in peak at 0.83\({}^{\circ}\) for SBA-15 with 33 and 50% PIL loading is a result of pore swelling due to [TEPA][NO\({}_{3}\)] impregnation. In the study that was conducted at 40 \({}^{\circ}\)C and 0.15 bar, the CO\({}_{2}\) adsorption capacity by [TEPA][NO\({}_{3}\)]/SBA-15 was higher than pristine adsorbent owing to the presence of ILs that provides an additional active site for sorbent interaction. Nevertheless, the breakthrough time and CO\({}_{2}\) adsorption capacity decreased as IL loading exceeded 66% due to pore blockage and the loss of internal surface area. Regarding the effect of temperature, the CO\({}_{2}\) adsorption capacity started to decline as the temperature increased above 60 \({}^{\circ}\)C due to thermodynamics effect causing CO\({}_{2}\) desorption rate higher than adsorption capacity. On the other hand, [PERSON] et al. immobilized two types of IL, [i-C\({}_{5}\)mim] and [BMIM], coupled with several anions, namely, [Cl]\({}^{-}\), [Tf\({}_{2}\)N]\({}^{-}\), [PF\({}_{6}\)]\({}^{-}\) and [DCN]\({}^{-}\) in commercial mesoporous silica [99]. In this work, the hybrid materials were prepared by dissolving Cl-based ILs in a mixture of toluene and mesoporous silica for 48 h at 95 \({}^{\circ}\)C. The unreacted reactant was then removed using Soxhlet extraction, and anion exchange was carried out in the mesoporous silica by using similar procedure as of [PERSON] et al. and [PERSON] et al. Analysis on solid state \({}^{13}\)C NMR of modified silica showed the presence of imidazolium ring which indicated the inclusion of ILs. Additional analysis of an NMRrelaxation study revealed a more mobile proton population caused by the IL moiety. Besides that, EDS analysis confirmed the successful anion exchange of ILs on grafted mesoporous silica. Furthermore, the surface area and pore volume of modified mesoporous silica was significantly reduced compared to the original material. Immobilizing ILs into mesoporous silica significantly diminishes the CO\({}_{2}\) uptake capacity due to reduction in surface area and pore volume. However, it has been found that 5 wt% [i-C\({}_{\text{sim}}\)][Tf\({}_{\text{g}}\)N] modified silica recorded up to 79.50 \(\pm\) 70 percent of CO\({}_{2}\) sorption capacity, virtually equivalent to pristine material (81.70 \(\pm\) 2.20). The study on the anion effect also demonstrated that ILs with [Tf\({}_{\text{g}}\)N]\({}^{-}\) and [PF\({}_{\text{6}}\)]\({}^{-}\) improve the selectivity CO\({}_{2}\)/N\({}_{2}\) due to CO\({}_{2}\) strong affinity towards fluorinated anion.