咪唑类离子液体催化四氢噻吩氧化脱硫机理*

Mechanism of Oxidative Desulfurization of Tetrahydrothiophene Catalyzed by Imidazole Ionic Liquid

陈 凯 张建亮 杨德伟 王新伟 林日亿

CHEN Kai ZHANG Jianliang YANG Dewei WANG Xinwei LIN Riyi

离子液体作为催化剂在石油脱硫过程中有独特优势，特别是对噻吩类硫化物。本文以四氢噻吩为模型化 合物，过氧化氢为氧化物，根据密度泛函理论，研究了咪唑氯铝酸盐离子液体催化四氢噻吩（THT）氧化为砜类的 反应机理，探讨了不同阳离子的离子液体催化性能的差异。通过离子液体在催化过程中与反应物、产物的作用 结构，发现离子液体与产物砜具有更强的相互作用，阳离子侧链越长作用结构越稳定；根据作用后稳定结构的电 荷布局、前线轨道性质，发现作用后THT上S原子有电荷富集现象，电子整体上从THT转移到离子液体，并在分 子层面解释了离子液体对反应物键能、键长、电荷布局的作用机理；最后计算氧化反应能垒，证明了加入离子液 体可使得反应能垒降低55%以上，且阳离子侧链越长，效果越显著。

Ionic liquids have unique advantages as catalysts in petroleum desulfurization，especially for thiophene sulfides. In this paper，tetrahydrothiophene （THT） was selected as a model compound and hydrogen peroxide as the oxide. Using density functional theory，ionic liquid was selected as catalyst，and the catalytic mechanism in the oxidation of tetrahydrothiophene to sulfone was studied. Cationic chain length was changed，and the influence of different side chains on catalytic effect was explored. The selective complexation mode of ionic liquids with reactants and products showed that ionic liquids had stronger interaction with the oxidation product sulfone. The longer the cationic side chain，the more stable the complex structure. The charge population and the properties of Frontier Molecular Orbital of the complex showed S atom on THT had charge enrichment，while the electrons transferred from THT to the ionic liquid during the complexation process. The influence of ionic liquid on the bond energy，and charge population of the reactants was explored at molecular level. The energy barrier of the reaction process proved ionic liquid reduced the reaction energy barrier by more than 55%，and the longer cationic side chain，the more significant the effect.

10.19346/j.cnki.1000-4092.2021.04.024