Stable Porous Organic Polymers Used for Reversible Adsorption and Efficient Separation of Trace SO2

The development of porous solid adsorbents for selective adsorption and separation of SO2 has attracted much attention recently. Herein, we design porous organic polymers (POPs) decorated with pyridine ligands as building units (POP-Py) through a radical polymerization of the 2,5-divinylpyridine (v-Py) monomer. Due to its high BET surface area, nanoporosity, and excellent stability, the prepared POP-Py can be used for reversible adsorption and efficient separation of SO2. The POP-Py possesses a SO2 capacity of 10.8 mmol g–1 at 298 K and 1.0 bar, which can be well retained after 6 recycles, showing an excellent reversible adsorption capacity. The POP-Py also shows superior separation performance for SO2 from a ternary SO2/CO2/N2 mixture (0.17/15/84.83v%), giving a breakthrough time and a saturated SO2 capacity at 178 min g–1 and 0.4 mmol g–1. The retention time was well maintained even under high moisture conditions, confirming its superior water resistance. Furthermore, when other vinyl-functionalized organic ligand monomers (bipyridine, pyrimidine, and pyrazine) were employed for radical polymerization, all of the resultant porous organic ligand polymers (POP-BPy, POP-PyI, and POP-PyA) exhibited superior performance for reversible adsorption and efficient separation of SO2. The combined features of reversible adsorption, efficient separation, and water resistance are important for the industrial applications of these materials as SO2 adsorbents.