Novel Ether-Functionalized Pyridinium Chloride Ionic Liquids for Efficient SO₂ Capture

Sulfur dioxide (SO 2 ) emitted from the combustion of fossil flues is a major atmospheric pollutant that seriously threatens the environment and human health. The traditional methods for the removal and recovery of SO 2 are irreversible and can result in secondary pollution or suffer from solvent loss. Therefore, it is urgent to explore new absorbents for the reversible, efficient, and environment-friendly capture of SO 2 . Ionic liquids (ILs) exhibit excellent performance for SO 2 capture because of their unique physicochemical properties. To improve the absorption capacities of ILs for SO 2, a series of novel ether-functionalized pyridinium chloride ILs ([E n Py]Cl, n = 2–4) were designed and synthesized. The physiochemical properties of these ILs and their SO 2 absorption performance under different conditions were investigated. In addition, the SO 2 /CO 2 selectivities and reusabilities of the ILs and the absorption mechanism between SO 2 and [E n Py]Cl ( n = 2–4) were studied. It was found that 1-[2-(2-methoxyethoxy)ethyl] pyridinium chloride showed a relatively high absorption capacity of up to 1.155 (g of SO 2 )·(g of IL) −1 at 20 °C and 0.1 MPa. The SO 2 absorption capacities of the studied ILs remained steady in absorption–desorption cycles, implying that [E n Py]Cl ( n = 2–4) could be promising candidates for SO 2 capture.