Abstract:

The cycloaddition of CO₂ with epoxide is an effective and sustainable strategy for the chemical conversion of CO₂, and its product, cyclic carbonate, is applied widely in the fields of lithium-ion batteries and polymer materials. For the cycloaddition of CO₂ with epoxide, it is crucial to construct catalysts with efficient epoxide adsorption activation sites since the ring-opening of the epoxide is deemed to be the key step. In this paper, TA-Zr-2, a non-homogeneous tannic acid-zirconium mesoporous material containing both Lewis acid site of zirconium metal center and hydrogen-bonding site of phenolic hydroxyl, was prepared via the coordination of tannic acid and zirconium ions. XPS and epichlorohydrin TPD-MS results showed that the zirconium metal center of TA-Zr-2 had stronger Lewis acidity and adsorption activation to epoxypropane compared to UiO-66 which was also a zirconium-based porous material. The TA-Zr-2-FD catalyst was obtained by freeze-drying treatment on basis of TA-Zr-2, and the catalytic performance was improved 1 times to TA-Zr-2 with 97.6% yield of butylene carbonate due to the larger specific surface area and suitable pore volume. In summary, a tannic acid-zirconium mesoporous material with large specific surface area was constructed by using a simple and green preparation method. The synergy of zirconium Lewis acid site and phenol hydroxyl hydrogen-bonding was beneficial to the adsorption and activation of epoxide, thus facilitating the epoxide ring-opening and enabling the catalyst to exhibit good catalytic performance for cycloaddition of CO₂ with epoxide at 25℃.

Key words: CO₂ conversion, cycloaddition reaction, cyclic carbonate, mesoporous material

摘要：

CO₂和环氧化物的环加成反应是一种有效且可持续的CO₂化工转化策略，其产品环碳酸酯在锂离子电池、高分子材料等领域具有广泛应用。其中环氧化物的开环被认为是该反应的关键步骤，因此构筑具有高效环氧化物吸附活化位点的催化剂至关重要。本文通过单宁酸与锆离子的配位作用，“一锅法”制备同时含有锆金属中心作为Lewis酸位点和酚羟基作为氢键作用位点的非均相单宁酸-锆介孔材料TA-Zr-2。XPS和环氧丙烷TPD-MS结果表明，与同为锆基多孔材料的UiO-66相比，TA-Zr-2的锆金属中心具有更强的Lewis酸性，对环氧丙烷具有更强的吸附活化作用。在TA-Zr-2的基础上通过冷冻干燥优化处理得到了具有更大比表面积和合适孔体积的TA-Zr-2-FD材料，25℃下催化性能提升1倍，24h的碳酸丁烯酯收率达97.6%。本文使用简单绿色的制备方法，构建了具有较大比表面积的单宁酸-锆介孔材料，锆Lewis酸位点和酚羟基氢键位点的耦合使其具有良好的环氧化物吸附活化作用，利于环氧化物的开环，使得该催化剂在25℃下表现出良好的CO₂环加成反应催化性能。

关键词: CO₂转化, 环加成反应, 环状碳酸酯, 介孔材料