Acylamido-Based Anion-Functionalized Ionic Liquids for Efficient SO₂ Capture through Multiple-Site Interactions

Acid gases such as SO 2 can be absorbed by ionic liquids (ILs) because of their unique properties. In this work, we developed a new approach for improving SO 2 absorption by novel acylamido-based anion-functionalized ILs. Several kinds of such ILs with different structures of acylamido group (anionic acylamide) were designed, prepared, and used for efficient capture of SO 2 . It was shown that these acylamido-based ILs strongly interacted with SO 2, resulting in a very high SO 2 capacity up to ∼4.5 mol SO 2 per mole of IL. The interactions between acylamido-based ILs and SO 2 were investigated by FT-IR, NMR, and quantum chemical calculations. It was found that the dramatic enhancement of SO 2 absorption capacity was originated from the multiple-site interactions such as N···S and C═O···S interactions between the anion and SO 2 . Furthermore, the captured SO 2 was easy to release by heating or bubbling N 2 through the SO 2 -saturated ILs. This novel strategy provides an excellent alternative to current SO 2 capture technologies.