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

Cui, Guokai, Zhang, Fengtao, Zhou, Xiuyuan, Huang, Yanjie, Xuan, Xiaopeng, Wang, Jianji
ACS sustainable chemistry 2015 v.3 no.9 pp. 2264-2270
Fourier transform infrared spectroscopy, absorption, gases, ionic liquids, nitrogen, nuclear magnetic resonance spectroscopy, sulfur dioxide
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 ILs 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 ILs strongly interacted with SO₂, 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···S and CO···S interactions between the anion and SO₂. Furthermore, the captured SO₂ was easy to release by heating or bubbling N₂ through the SO₂-saturated ILs. This novel strategy provides an excellent alternative to current SO₂ capture technologies.