(377u) Mechanism of SO2 absorption in Ionic Liquids

Sulfur dioxide (SO₂) has been resulting in a serious harm to environment and human health. On the other hand, SO₂ also is an important source for synthesizing chemicals. Recently, ionic liquids (ILs) have been regarded as one of the most promising alternative solvents for capturing SO₂ due to their special physicochemical properties, such as negligible vapor pressure and designable character. For example, it was found that N-butylpyridinium thiocyanate ([C₄Py][SCN]) can absorb 0.841 gSO₂/g IL at 293 K and 0.10 MPa¹.

In this work, the mechanism of SO₂ absorption in different kinds of ILs were systemically studied by molecular simulations. The microscopic structure, interaction energy and dynamic properties of the mixtures of ILs and SO₂ were investigated. The results of the radial distribution functions and spatial distribution functions show that SO₂ are mainly distributed above and below the center carbon plane of the cations, while the anions mainly exhibit strong affinity toward the most acidic hydrogen atoms of the cations. Anion has the closest affinity with SO₂ than cation, which in charge of offering interaction sites to attract SO₂. However, the cations also are crucial for SO₂ absorption, which mainly provide space for accommodating SO₂.

Acknowledgment

This work was supported by the National Natural Scientific Fund of China (51674234).

Reference

1. J. Zeng, H. S. Gao, X. C. Zhang, H. F. Dong, X. P. Zhang, S. J. Zhang, Chem. Eng. J, 2014, 251, 248-256.