Nitrogen-rich covalent-organic-framework as a recyclable heterogenous catalyst for the efficient cycloaddition of carbon dioxide with epoxides

Carbon dioxide (CO2) can be chemically converted into high-value products, which is not only helps to ease the environmental problems instigated by global warming and has an optimistic effect on economies around the planet. The production of cyclic carbonates is regarded as a promising approach to convert CO2 through the cycloaddition of CO2 with epoxides. However, a major obstacle in this process is the synthesis of environmentally friendly and highly effective heterogeneous catalysts. Here, a novel nitrogen-rich covalent organic framework (CP-COF) was firstly synthesized through a polymerization method of piperazine and cyanuric chloride with 1, 4‐dioxane and used for the aforesaid reaction. A number of analytical methods were employed to verify the chemical composition and the structure of the catalyst. The CP-COF catalyst possessed a significant amount of active nitrogen sites and hydrogen bond donors in it, resulting in a high level of reactivity for the cycloaddition reaction of CO2 with epichlorohydrin in the absence of any solvent and metals, and the yield of chloropropene carbonate (CPC) reached 99 % at 110 ℃, 6 h and 1 MPa CO2 pressure. The CP-COF sample exhibited commendable activity towards a range of epoxides. Moreover, it showed high reusability for the reaction without any loss in the catalytic efficiency.