| Summary: | Much effort has been devoted to the development of efficient heterogeneous catalysts for the conversion of carbon dioxide (CO<sub>2</sub>) into high-value chemicals. Generally, the cycloaddition of CO<sub>2</sub> to epoxides is considered a green and atom-economic reaction for the production of cyclic carbonates. Based on this, three kinds of silicon-based catalysts modified using zinc(Ⅱ) 2-bromoacetic (Si-ZnBA-n, n = 1, 2, 3) were facilely synthesized and employed for the chemical fixation of CO<sub>2</sub> to epoxides with the use of potassium iodide (KI). A series of characterization techniques were used to characterize the textual structures and physicochemical properties of Si-ZnBA-n. The synergistic effects of Zn, –NH<sub>2,</sub> –OH and the nucleophilic group guaranteed the catalytic activity of Si-ZnBA-n. Si-ZnBA-1 exhibited the best catalytic activity among Si-ZnBA-n because Si-ZnBA-1 possessed the highest Zn content. Additionally, the effects of the reaction conditions (temperature, pressure, time and catalyst loadings) were also discussed. The propylene carbonate (PC) yield could reach 97% under 130 °C, 2 MPa, for 5 h without the employment of organic solvent, and its selectivity was 99%. In addition, the recycling property of Si-ZnBA-1/KI was also investigated, and the catalytic system exhibited good cycle performance. Meanwhile, the catalyst showed outstanding versatility for CO<sub>2</sub> application to various epoxides, and a possibly synergistic reaction mechanism was proposed. Finally, a dynamic model was developed to discuss the activation energy of the CO<sub>2</sub> cycloaddition reaction over the Si-ZnBA-1 catalyst.
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