Porous sulfonyl binuclear carbonate poly(ionic liquid)s for one-pot fixation of diluted CO₂ into dimethyl carbonate

The direct utilization of diluted CO₂ skips the additional enrichment and purification operations required for high-purity CO₂, making it shine in the green catalytic process. However, achieving diluted CO₂ cycloaddition coupling transesterification with epoxide and methanol over poly(ionic liquids) catalyst and understanding the relevant mechanism at the molecular level are still challenging. Here, a novel porous sulfonyl binuclear carbonate poly(ionic liquid)s (SC-PILs) were successfully prepared by the integration of acidic monomers pre-polymerization with basic anions post-etching, regulating the chemical property of free anions and increasing the specific surface area of copolymerized materials. Relying on the synergy of the built abundant pores and the exposed basic anions, SC-PILs could one-pot efficiently catalyze the cycloaddition coupling transesterification reaction of the simulated flue gas (15% CO₂ + 85% N₂) without any co-catalyst, and dimethyl carbonate (DMC) with the yield of 80% was obtained. Theoretical studies deeply understood the activation difference of binuclear CO₃²⁻ anion on CO₂ compared with mononuclear CH₃COO⁻ anion and the ring-opening mechanism of [CO₃²⁻+CO₂] adduct on epoxides, providing a better choice for high-value utilization of diluted CO₂ from flue gas.