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

Acid gases such as SO2 can be absorbed by ionic liquids (ILs) because of their unique properties. In this work, we developed a new approach for improving SO2 absorption by novel acylamido-based anion-functionalized ILs. Several kinds of such Its with different structures of acylamido group (anionic acylamide) were designed, prepared, and used for efficient capture of SO2. It was shown that these acylamido-based Its strongly interacted with SOD resulting in a very high SO2 capacity up to 4.5 mol SO2 per mole of IL. The interactions between acylamido-based ILs and SO2 were investigated by FT-IR, NMR, and quantum chemical calculations. It was found that the dramatic enhancement of SO2 absorption capacity was originated from the multiple-site interactions such as N center dot center dot center dot S and C=O center dot center dot center dot S interactions between the anion and SO2. Furthermore, the captured SO2 was easy to release by heating or bubbling N-2 through the SO2-saturated ILs. This novel strategy provides an excellent alternative to current SO2 capture technologies.