Low‐cost robust covalent organic framework with pyridine sites for deep flue gas desulfurization

The practical deployment of covalent organic frameworks (COFs) for industrial gas separations is hindered by synthetic complexity, high monomer costs, and insufficient stability. We report a pyridine‐functionalized, vinylene‐linked COF (2,4,6‐trimethylpyridine‐terephthalaldehyde‐COF [TMP‐TPA‐COF]) that overcomes these barriers. Synthesized from inexpensive monomers (TMP and TPA) via one‐pot Knoevenagel condensation, TMP‐TPA‐COF has robust C=C linkages enabling hectogram‐scale synthesis. It exhibits a surface area of 1467 m 2 g −1 and static sulfur dioxide (SO 2 ) adsorption of 14.8 mmol g −1 at 25°C. Under simulated flue gas (6000 ppm SO 2 , 15% CO 2 , balance N 2 ), dynamic breakthrough shows a working capacity of 1.51 mmol g −1 and high selectivities, driven by Lewis acid–base interactions with pyridine sites. It is fully regenerated at 120°C under N 2 , retaining 95% capacity over 15 cycles. Its monomer cost is orders of magnitude lower than benchmark COFs, challenging the view that COFs are impractical for large‐scale applications and establishing a cost‐effective sorbent for deep SO 2 removal.