Cycloaddition Reaction of Carbon Dioxide to Epoxides Catalyzed by Polymer-Supported Quaternary Phosphonium Salts

Polymer-supported quaternary phosphonium salt (PS-QPS) was explored as effective catalyst for the coupling reaction of carbon dioxide with epoxides. The results indicated that cyclic carbonates with high yields (98.6%) and excellent selectivity (100%) could be prepared at the conditions of 5 MPa CO2, 150°C, and 6 h without the addition of organic solvents or cocatalysts. The effects of various reaction conditions on the catalytic performance were investigated in detail. The catalyst is applicable to a variety of epoxides, producing the corresponding cyclic carbonates in good yields. Furthermore, the catalyst could be recovered easily and reused for five times without loss of catalytic activity obviously. A proposed mechanism for synthesis of cyclic carbonate in the presence of PS-QPS was discussed. The catalyst was characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectrum. It is believed that PS-QPS is of great potential for CO2 fixation applications due to its unusual advantages, such as easy preparation, high activity and selectivity, stability, low cost, and reusability.