The Heptazine-Based Materials through Intrinsically Modification for the Cycloaddition of CO2 and Bisepoxides

Graphical The efficient utilization of CO 2 into cyclic carbonate as electrolytes and medical intermediates with 100 % atom efficiency is interesting. Employed as catalyst, carbon nitride family with different polymerization degree and pore structure exhibits excellent potential in the cycloaddition reaction. The active amino and hydroxyl groups in the catalyst form interaction with CO 2 molecules and epoxy groups, respectively, generating the synergistic effect to promote the reaction. For the efficient utilization of CO 2 into valuable product, the attractive carbon nitride catalysts have been widely studied. In this work, heptazine-related materials with varying degree of polymerization were designed by an intrinsically modification strategy and employed in the cycloaddition of CO 2 with the bisepoxide 1, 4-butanediol diglycidyl ether (BDODGE). We initially figured out that the sample prepared at 450 °C contained more melem hydrate, exhibiting the best performance. The epoxides conversion and corresponding cyclic carbonates selectivity could achieve 93.1 % and 99.3 % at 140 °C for 20 h without any cocatalyst and solvent, respectively. Results of the catalytic tests suggested that the high catalytic activity was dependent on big size porous structure and the synergetic effect of active amino groups and −OH groups. The role of water in maintaining the specific structure and providing active site has been proved. Moreover, the CN-450-W catalyst exhibited outstanding recycling stability. And finally, a plausible reaction mechanism was proposed.