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

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.