Catalytic oxidative desulfurization systems based on Keggin phosphotungstate and metal-organic framework MIL-101

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• 作者：Susana Ribeiro ; Andr¨¦ D.S. Barbosa ; Ana C. Gomes ; Martyn Pillinger ; Isabel S. Gon?alves ; Lu¨ªs Cunha-Silva ; Salete S. Balula
• 关键词：Oxidative desulfurization ; Keggin-type polyoxometalate ; Metal-organic framework ; MIL-101 ; Benzothiophene derivatives
• 刊名：Fuel Processing Technology
• 出版年：2013
• 出版时间：December, 2013
• 年：2013
• 卷：116
• 期：Complete
• 页码：350-357
• 全文大小：871 K

文摘

The tetrabutylammonium salt of phosphotungstic acid, TBA₃PW₁₂O₄₀ (PW₁₂), has been encapsulated in the chromium terephthalate metal-organic framework MIL-101. Characterization of the composite PW₁₂@MIL-101 by powder X-ray diffraction, FT-IR, FT-Raman and ³¹P magic-angle spinning (MAS) NMR spectroscopies confirmed that the structures of MIL-101 and the polyoxometalate anion were retained after immobilization. Both PW₁₂ and the composite material were examined as catalysts in systems for the oxidative desulfurization (ODS) of model oils containing dibenzothiophene (DBT), 1-benzothiophene (1-BT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate was employed as both extractant and reaction medium. In a one-pot operation carried out at 50 ¡ãC, the BT derivatives in the model oils were extracted into the IL and then oxidized (using 30 % H₂O₂ as oxidant) to form the corresponding sulfones, resulting in a continuous decrease in the sulfur content in the oil phase. The sulfur removal from the model oil with a sulfur content (for each BT derivative) of 500 ppm reached 100 % within 1 h for DBT, 100 % within 3 h for 1-BT, and 99 % within 4 h for 4,6-DMDBT (sulfur content, 3-7 ppm). The ODS system containing the composite PW₁₂@MIL-101 could be recycled three times with only a slight decrease in the catalytic performance.