β-Ketoenamine Porous Organic Polymers for High-Efficiency Carbon Dioxide Adsorption and Separation

To mitigate the greenhouse effect, a number of porous organic polymers (POPs) has been developed for carbon capture. Considering the permanent quadrupole of symmetrical CO₂ molecules, the integration of electron-rich groups into POPs is a feasible way to enhance the dipole-quadrupole interactions between host and guest. To comprehensively explore the effect of pore environment, including specific surface area, pore size, and number of heteroatoms, on carbon dioxide adsorption capacity, we synthesized a series of microporous POPs with different content of β-ketoenamine structures via Schiff-base condensation reactions. These materials exhibit high BET specific surface areas, high stability, and excellent CO₂ adsorption capacity. It is worth mentioning that the CO₂ adsorption capacity and CO₂/N₂ selectivity of TAPPy-TFP reaches 3.87 mmol g^-1 and 27. This work demonstrates that the introduction of β-ketoenamine sites directly through condensation reaction is an effective strategy to improve the carbon dioxide adsorption performance of carbon dioxide.