Synthesis of imidazolium-functionalized COFs and their catalytic performance in cycloaddition of CO2 with propylene oxide to propylene carbonate

Abstract

Herein, we constructed a novel heterogeneous catalyst, ionic liquid-functionalized triazine–pyridine–hydroxyl covalent organic frameworks (ILs-TPN-COFs), through synthesis of new covalent organic frameworks (COFs) followed by modification with imidazole-based ionic liquids. A series of characterization techniques, such as NMR, FT-IR, and XPS, verified the successful preparation of the catalyst. The catalytic performance of ILs-TPN-COFs was evaluated in the cycloaddition reaction of CO₂ and propylene oxide (PO) to produce propylene carbonate (PC). Under optimized reaction conditions (160 °C, 2.0 MPa, 2.5 wt% catalyst amount, 8 h), the PC yield was up to 99.23%. Furthermore, the response surface experiment (RSM) was conducted on the reaction; the predicted results exhibited excellent agreement with the experimental results, indicating that the model is accurate. This work offers valuable insights into the synergistic effects of multi-component catalysts for the design and development of CO₂ cycloaddition reactions.