DFT study of the interaction between ethanethiol and Fe-containing ionic liquids for desulfuration of natural gasoline

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• 作者：José ; -Manuel Martí ; nez-Magadá ; n^b ; Raú ; l Oviedo-Roa^a ; Paloma Garcí ; a^a ; Rafael Martí ; nez-Palou^a ; ^{rpalou@imp.mx}
• 关键词：Density Functional Theory ; Desulfurization ; Fe-containing ionic liquids ; Ethanethiol
• 刊名：Fuel Processing Technology
• 出版年：2012
• 期刊代码：36_03783820
• 类别：ce
• 出版时间：May, 2012
• 卷：97
• 期：Complete
• 页码：24-29
• 文件大小：441 K

摘要

The interaction between ethanethiol molecule and either anhydrous Fe^III chloride anions or 1-butyl-3-methylimidazolium ([BMIM]⁺) cations of ionic liquids (ILs) was investigated using Density Functional Theory approach and results were correlated with our previous experimental results on extractive desulfurization (EDS), where ILs containing anionic Fe^III species show excellent performance to remove sulfur compounds from natural gasoline, especially when there exists an excess of FeCl₃ in the [BMIM]⁺[FeCl₄]^{鈭?/sup> IL since this mixture contains binuclear anions [Fe₂Cl₇]鈭?/sup>, whose Fe鈥旵l鈥旻e bonds are larger and less strong than Fe鈥旵l bonds of mononuclear anions [FeCl₄]鈭?/sup>, being then the former bonds activated for ethanethiol chemisorption. Molecular frontier orbitals and Mulliken atomic charges reveal that the high desulfurization performance could be due to a Dewar-Chatt-Duncanson-like mechanism of electron donation-backdonation among ethanethiol sulfur and transition metal centers of [Fe₂Cl₇]鈭?/sup> anions, and this mechanism is promoted because of the symmetry affinity among the ethanethiol HOMO and the atomic orbital t_2g on Fe sites in [Fe₂Cl₇]鈭?/sup> LUMO. On the other hand, when there is no excess of FeCl₃, EDS increases with the size of N-alkyl substitutes in [BMIM]+ due to ethanethiol physisorption by these cations.}