Optimization and kinetics modeling of CO2 fixation into cyclic carbonates using urea-functionalized ionic organic polymers under mild conditions

Ionic organic polymeric materials are one of the most promising catalysts for the conversion of carbon dioxide (CO2) to five-membered cyclic carbonates (5CCs). Herein, a series of urea functionalized ionic organic polymer materials UIPs (UIP-1, UIP-2 and UIP-3) have been prepared by condensation and Menshutkin reaction of three components in one-pot by solvothermal method. After characterization by FT-IR, SEM, 13C CP MAS NMR, TGA, N2 adsorption and oS spectroscopy, the UIPs were alternated as competitive catalysts for the CO2 cycloaddition reaction with epoxides without metal and co-catalyst under solvent-free conditions. In particular, UIP-2, derived from 1,3,5-tribromomethyl benzene, 4-amino pyridine and 4,4 '-diphenylmethane diisocyanate, demonstrated excellent catalytic activity in the CO2 cycloaddition reaction with a high cyclic carbonate yield of 92.6 % under mild conditions: epichlorohydrin (ECH) (10 mmol), UIP-2 (0.10 mmol), reaction at 70 degrees C for 16 h with 1 bar of CO2, and the activated energy was calculated to be 48.5 kJ/mol. Furthermore, a possible catalytic mechanism was proposed by experiments and density functional theory (DFT) calculations.