Experimental and theoretical investigation of phenylpyridine-based hypercrosslinked polymers for atmospheric CO2 adsorption and fixation under solvent-/metal-free conditions

Several phenylpyridine- and phenyl-based hypercrosslinked polymers (HCPs) were prepared via a one-step Friedel-Crafts polymerization and used as catalysts for the cycloaddition reaction between atmospheric CO2 and epoxides to produce cyclic carbonates. The structural characteristics and catalytic activity of different HCP catalysts were compared, while the recycling performance and universality to various substituted epoxides were investigated. The as-prepared catalysts exhibited regular pore structure and high specific surface area (1133 m2/g). Under the synergistic effect of tetrabutylammonium iodide (TBAI), the optimized TPA-HCP-Py efficiently converted atmospheric CO2 into cyclic carbonates with good to excellent product yields. Furthermore, the TPA-HCP-Py catalyst was easy to recover, and no significant changes were observed after reusing for five times, which demonstrated its excellent recycling performance. The interactions between different active sites and reactants in the TPA-HCP-Py/TBAI catalytic system were investigated by DFT calculation, revealing the catalytic reaction mechanism and providing valuable guidance for developing new multifunctional catalysts.