One-pot efficient fixation of low-concentration CO2 into cyclic carbonate by mesoporous pyridine-functionalized binuclear poly(ionic liquid)s

Abstract

The direct conversion of low-concentration CO2 from flue gas avoids the energy-intensive purification and concentration of CO2 to implement the next utilization, making it undoubtedly a green process. However, achieving low-concentration CO2 cycloaddition with epoxide over functional poly(ionic liquid) catalysts and understanding the relevant mechanism at the molecular level is still challenging. Here, novel mesoporous pyridine-functionalized binuclear poly(ionic liquid)s (PB-PIL)s were successfully synthesized by the polymerization of DVB, basic monomers, and binuclear ionic liquid monomers, regulating the density of pyridine sites and binuclear halogen counterions to achieve the optimum balance between the active sites and pore structure of copolymerized materials. Remarkably, PB-PILs were active in the cycloaddition reaction of the low-concentration CO2 (15% CO2 + 85% N2) without any co-catalyst and gave a 95% yield of cyclic carbonate. Relied on DFT theoretical calculation, the activation degree of pyridine to CO2 and the promotion of CO2 insertion were deeply explored, providing more broad ideas for the conversion of low-concentration CO2.