CO₂ capture using silica-immobilized dicationic ionic liquids with magnetic and non-magnetic properties

The need to find alternative materials to replace aqueous amine solutions for the capture of CO₂ in post-combustion technologies is pressing. This study assesses the CO₂ sorption capacity and CO₂/N₂ selectivity of three dicationic ionic liquids with distinct anions immobilized in commercial mesoporous silica support (SBA- 15). The samples were characterized by UART-FTIR, NMR, Raman, FESEM, TEM, TGA, Magnetometry (VSM), BET and BJH. The highest CO₂ sorption capacity and CO₂/N₂ selectivity were obtained for sample SBA@DIL_2FeCl₄ [at 1 bar and 25 °C; 57.31 (±0.02) mg CO₂/g; 12.27 (±0.72) mg CO₂/g]. The results were compared to pristine SBA-15 and revealed a similar sorption capacity, indicating that the IL has no impact on the CO₂ sorption capacity of silica. On the other hand, selectivity was improved by approximately 3.8 times, demonstrating the affinity of the ionic liquid for the CO₂ molecule. The material underwent multiple sorption/desorption cycles and proved to be stable and a promising option for use in industrial CO₂ capture processes.