The Synthesis of Cyclic Carbonate Catalyzed by Immobilized Ionic Liquid

The alcohol amine ionic liquid (TEA) was grafted onto chloromethyl polystyrene (PS-Cl) microspheres through alkylation reaction and the simple one-pot method and the resulting ionic liquid-supported catalyst (PS-TEAI) was used to catalyze the formation of cyclic carbonates from carbon dioxide and epoxides. The structure and morphology of the catalyst were characterized with the Fourier transform infrared spectroscopy (FT-IR) and the scanning electron microscope (SEM). The grafting amount and the thermal stability of alcohol amine ionic liquids were studied with the X-ray photoelectron spectroscopy (XPS), the elemental analysis (EA) and the thermogravimetric analysis (TGA). In the cycloaddition reaction, the catalyst did not require solvents and co-catalysts. Under the experimental conditions of catalyst dosage of 0.10 g, 120 ℃ temperature, 2 MPa CO₂ pressure and 4 h reaction time, the yield of propylene carbonate (PC) reached 93.30%. It was easy to separate after the reaction and could be reused. The reaction mechanism of hydrogen bond formed with hydroxyl activating epoxide and I^- nucleophilic attack to promote ring opening was finally proposed.