Incorporation of phenolic skeleton into imidazolium ionic polymers as recyclable catalysts for efficient fixation of CO2 into cyclic carbonates

Developing a greener and efficient catalysts towards the direct fixation of atmospheric CO 2 and then being used to synthesize high-value chemicals is of great interest, but challenging. To achieve this aim, rational design of the catalyst is very important. Herein, three imidazolium-based ionic polymers (IPs), named as IP 1–IP 3 , are straightforwardly synthesized through a simple one-pot quaternization method by employing benzyl chloride linkers and tri-imidazole monomers ( L 1 and L 2 ). These IPs are fully characterized using FTIR spectroscopy, 13 C MAS NMR, XRD, elemental analysis, SEM with elemental mapping, HRTEM, TGA, XPS spectroscopy, nitrogen adsorption–desorption, and CO 2 /NH 3 -TPD methods. The newly synthesized IP 1 catalyst with phenolic hydroxyl shows an excellent catalytic activity toward CO 2 cycloaddition with 97.1 % yield of cyclic carbonate under mild conditions (80 °C, 0.1 MPa CO 2 , solvent-free, 4.5 h). Moreover, the IP 1 catalyst is highly robust and can be reused at least for 7 consecutive runs. Mechanistic studies indicate that the synergic effect of hydrogen bonding and halogen anion in the IP 1 catalyst afford the ability to activate the substrate and ease the reaction kinetics, which results in an enhanced catalytic efficiency toward CO 2 fixation. This work provides an efficient new method for the design and synthesis of multifunctional heterogeneous catalysts for the CO 2 cycloaddition reaction.