The cycloaddition reaction of carbon dioxide (CO₂) and bisepoxides is an interesting route for CO₂ utilization and green non-isocyanate polyurethane (NIPU) synthesis. In this work, a series of γ-Al₂O₃ supported ZnBr₂ and carbon nitride complex catalysts (Zn–CN/γ-Al₂O₃) were prepared by a simple thermal polymerization method and applied to the cycloaddition reaction. The results showed that 0.05Zn–CN/γ-Al₂O₃ exhibited high catalytic activity, over which 91.4% 1,4-butanediol diglycidyl ether (BDODGE) conversion and 98.9% cyclic carbonate selectivity were acquired under solvent and co-catalyst free conditions. The relationship between the structural properties and catalytic performance of Zn–CN/γ-Al₂O₃ catalysts was studied in detail. It is found that the high surface area and the synergistic effect of Lewis acid–base duality are key factors for the high activity of catalysts. Introducing ZnBr₂ could provide acid sites and induce structure change of carbon nitride, which could determine the basic intensity of catalysts. Moreover, based on the elaborate discussions, a plausible catalytic reaction mechanism was proposed.

中文翻译：

---

负载的 ZnBr ₂和氮化碳双功能复合催化剂，可有效地使CO ₂与二缩水甘油醚进行环加成反应†

二氧化碳（CO ₂）和双环氧化物的环加成反应是利用CO ₂和合成绿色非异氰酸酯聚氨酯（NIPU）的有趣途径。在这项工作中，一系列的γ-Al的₂ ö ₃支持的ZnBr ₂和氮化碳络合物催化剂（ZN-CN /γ-Al系₂ ö ₃）通过简单的热聚合方法制备并施加到环加成反应。结果表明，0.05Zn-CN /γ-Al系₂ ö ₃具有较高的催化活性，在无溶剂和助催化剂的条件下，获得了91.4％的1,4-丁二醇二缩水甘油醚（BDODGE）转化率和98.9％的环状碳酸酯选择性。的结构特性和Zn-CN /γ-Al系的催化性能之间的关系_2种ö ₃催化剂进行了详细研究。发现高表面积和路易斯酸-碱二元性的协同作用是催化剂高活性的关键因素。引入ZnBr ₂可以提供酸性位点，并引起氮化碳的结构变化，从而可以确定催化剂的基本强度。此外，在详尽的讨论基础上，提出了合理的催化反应机理。