Multifunctional ionic covalent triazine framework as heterogeneous catalysts for efficient CO2 cycloaddition

The abundant triazine rings with the good affinity for CO 2 molecules in covalent triazine frameworks (CTFs) can capture and activate CO 2 molecules, making CTFs a potential candidate for CO 2 cycloaddition reaction. However, due to the single active site, the realization of high catalytic performance commonly requires the assistance of cocatalysts or harsh reaction conditions. In this study, several novel ionic covalent triazine frameworks (MCTFs, BCTFs and YCTFs) multifunctional heterogeneous catalysts were synthesized for CO 2 cycloaddition reactions. The prepared CTFs catalysts have outstanding pore structure and uniformly distributed active sites (N Lewis basic sites in triazine ring and Cl – nucleophilic sites). The optimal catalyst MCTF-10 has good CO 2 enrichment capacity and high adsorption selectivity. In addition, the catalyst shows an outstanding catalytic performance for the coupling reaction of CO 2 and propylene oxide, with 96 % of yield and 99 % of selectivity for the product under metal-, solvent- and cocatalyst-free parameters (110 °C, initial CO 2 pressure 1 MPa, 4 h). Even under diluted CO 2 concentration (15 % CO 2 , 85 % N 2 ) and mild conditions (80 °C, 0.1 MPa, 24 h), the synthetized CTFs exhibits an outstanding catalytic activity. The excellent catalytic performance, along with the good cycling stability and broad applicability of epoxides, make it a competitive catalyst for catalyzing the CO 2 cycloaddition reaction.