碳捕获转化视域下多孔共价有机聚合物的催化活性调控与环状碳酸酯合成性能研究

Study on Catalytic Activity Regulation of Porous Covalent Organic Polymers and Synthesis Performance of Cyclic Carbonates from the Perspective of Carbon Capture and Conversion

摘要: 二氧化碳是一种廉价、丰富而且可再生的C1资源，利用它与环氧化物进行环加成反应来合成环状碳酸酯，已经成为实现CO₂资源化利用的一条重要途径。共价三嗪框架(CTF)因为骨架中含有大量三嗪环结构，与CO₂之间存在着较强的相互作用，在CO₂捕获和转化领域得到了不少关注，但室温搅拌法直接合成出来的母体CTF，其催化活性相当有限。本论文尝试把温和条件下得到的CTF与一些常规助催化剂搭配起来，构建出一套高效的环加成催化体系。本研究选用三聚氯氰和1,4-苯二胺为原料，室温搅拌合成了母体CTF材料，并创新性地采用溶剂置换–冷冻干燥法进行后处理，以提高其孔隙率。通过FT-IR、BET和TGA对材料进行了系统表征。在此基础上，设计并实施了氨基封端控制实验和原位红外光谱实验，揭示了CTF表面氨基的氢键活化作用及协同催化循环中各组分的功能。催化性能评价结果表明，CTF与TBAB表现出最佳的协同催化效应。在110℃、1.5 MPa、反应时间3 h、TBAB用量为底物3 mol%的最优条件下，碳酸丙烯酯的产率可达73%。循环稳定性测试显示，该催化体系经5次循环后仍能保持较高的活性，证实了其良好的可重复使用性。本工作为温和条件下合成CTF并应用于CO₂环加成反应提供了详实的实验和理论依据，并为后续高性能催化剂的开发指明了方向。

Abstract: Carbon dioxide is an inexpensive, abundant and renewable C1 resource. The synthesis of cyclic carbonates via cycloaddition reaction between CO₂ and epoxides has become an important route for the resource utilization of CO₂. Covalent triazine frameworks (CTFs) possess abundant triazine rings in their skeletons, which generate strong interactions with CO₂. Therefore, CTFs have attracted substantial attention in the field of CO₂ capture and conversion. Nevertheless, the parent CTF directly synthesized by room-temperature stirring exhibits rather limited catalytic activity. In this paper, parent CTF obtained under mild conditions was combined with common cocatalysts to construct an efficient catalytic system for cycloaddition. Cyanuric chloride and 1,4-phenylenediamine were selected as raw materials to synthesize parent CTF via stirring at room temperature. A solvent exchange-freeze-drying method was innovatively adopted for post-treatment to improve its porosity. The materials were systematically characterized by FT-IR, BET and TGA. On this basis, amino-termination control experiments and in-situ infrared spectroscopy tests were designed and performed to reveal the hydrogen-bond activation effect of surface amino groups on CTF and the functions of each component in the synergistic catalytic cycle. Catalytic performance evaluation demonstrates that CTF combined with TBAB delivers the optimal synergistic catalytic effect. Under the optimal conditions (110˚C, 1.5 MPa, reaction time of 3 h, TBAB dosage of 3 mol% relative to substrate), the yield of propylene carbonate reaches 73%. Cycling stability tests show that the catalytic system retains high activity after 5 cycles, verifying its favorable reusability. This work provides detailed experimental and theoretical foundations for synthesizing CTFs under mild conditions and applying them in CO₂ cycloaddition reactions, and sheds light on the development of high-performance catalysts in follow-up research.