Catalytic Conversion Of CO₂ To Cyclic Oxides Over Layer-confined Ionic Liquids

The massive emission of carbon dioxides（CO₂）creates seriously burden on environments,especially greenhouse effects.However,as an abundant C₁ feedstock,CO₂ can be converted into valuable products.Among the various routes for the chemical fixation of CO₂,CO₂-derived cyclic carbonate is highly studied due to the atomic economy and environmental friendliness.Various catalysts have been developed for the synthesis of CO₂-derived cyclic carbonate.However,several issues including the separation of homogeneous catalyst,the loss of active components in heterogeneous catalyst,always results in the low catalytic activity.Herein,a high active heterogeneous catalytic was developed via loading functional ionic liquid in the interlayer gap,where the intrinsic properties of ionic liquid was highly reserved.This strategy proposes a novel method of designing ionic liquid-based heterogeneous catalytic.The main research works are summarized as the follows:1.To improve the ring opening of epoxides and activation of CO₂,a series of functional ionic liquids with different cation were designed benefiting from the synergistic effects between the pairs of cation and anion.The structures of ionic liquids were confirmed with ~1H NMR.The piperidine-based ionic liquid showed the highest catalytic performance with a high selectivity（91%）and productivity（91.9%）in a mild condition（120℃,0.3 MPa CO₂,12 h）due to the optimal alkalinity and best CO₂ adsorption capacity.2.To further improve the recycling performance and the catalytic activity of ionic liquid-based heterogeneous catalyst,ionic liquid catalysts confined in the layered structure with different ionic liquid contents were prepared by intercalating ILs3 into zirconium hydrogen phosphate（Zr P）via a simple co-assembly method.All of the SEM,FTIR,XRD,XPS,and TEM confirmed that ionic liquid was entirely confined within the interlayer gaps of Zr P.Moreover,the catalytic activity towards cycloaddition reaction of the interlayer confined structure was explored thoroughly.The thermal stability of ionic liquid was highly enhanced with the confined structure.Meanwhile,the catalytic with the lowest ionic liquid（the molar ratio of Zr P to ionic liquid is 1.5:1）content exhibits the higher catalytic activity than the parent IL3.Benefiting from the uniformly distributed ionic liquid within the confined structure and the layered structure of Zr P,the transmission of CO₂ and active intermediates was highly improved.The addition reaction of CO₂ and ECH reached a high productivity of cyclic carbonate（95.2%at 120℃,0.3 MPa CO₂,12 h）with the catalyst that the molar ratio of Zr P to ionic liquid is 1.5:1.