A Review of CO2 capture by Poly(Ionic liquid)s

Over the last two decades, poly(ionic liquid)s (PILs) have undergone extensive research and development. PILs have opened a whole new passage to versatile ionic polymers. It has compelled the chemical industry to rethink its modern ways of carbon capture. PILs have demonstrated excellent CO2 sorption capacities in comparison to their corresponding ionic liquids (ILs). The effects of the chemical structures of PILs on CO2 sorption, including the types of anion, cation, and backbone, have been discussed. This review aims to cover details of a large range of PILs along with their physical and structural properties, synthesis procedures, and the absorption power towards CO2. Imidazolium-based PILs are some of the strongest absorbents of CO2. On the other hand, PILs with amino acid (AA) anion seem to have a much-improved sorption capacity when compared PILs with the non-AA anionic part. PILs with hexafluorophosphate ion (PF6-) relatively absorb more CO2 compared to tetra-fluoroborate (BF4-) based PILs. The solubility of CO¬2 was increased with increasing pressure and decreased as temperature increased. The inclusion of hydroxyl groups in the polycation increased the interaction with CO2 molecules.¬ The COSMO-RS model was used to understand the molecular-level behavior of PILs in terms of their activity coefficients.