Abstract: As one of the energy-intensive processes, production of ethylene glycol with high selectivity from ethylene oxide under low hydration ratios is a challenge in the industry. In this study, a series of porous poly(ionic liquid)s with high specific surface area and macroporous structure were synthesized through free radical copolymerization of rigid ionic liquids and organic base monomers. The structure, microscopic morphology, and thermal stability of the poly(ionic liquid)s were characterized by magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), N2 physical adsorption-desorption, and thermogravimetric analysis (TGA). These poly(ionic liquid)s had a specific surface area ranging from 100.9 to 374.7 m2g?1, a pore volume ranging from 0.41 to 0.86 cm3g?1, with active sites uniformly distribute within the porous structure. Porous poly(ionic liquid)s possessing both the active centers of ionic liquids and organic bases could synergistically catalyze the CO2-promoted hydration of ethylene oxide. Under a low hydration ratio of 1.5:1, high yield (96.5 %) and selectivity (96.5 %) of ethylene glycol were achieved, which were comparable to the corresponding homogeneous catalysts. The CO2-promoted catalysis alters the pathway of hydration reaction, significantly reducing the hydration ratio and improving the selectivity of ethylene glycol. In addition, the catalyst had good substrate applicability and recyclability, and it also showed good catalytic performance under flue gas atmosphere.

Key words: Ethylene glycol, Ethylene oxide, Porous poly(ionic liquids), CO₂-promoted hydration reaction