The coordinatively saturated vanadium MIL-47 as a low leaching heterogeneous catalyst in the oxidation of cyclohexene

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• 作者：Karen Leus^a ; ¹ ; Matthias Vandichel^b ; ¹ ; Ying-Ya Liu^a ; Ilke Muylaert^a ; Jan Musschoot^c ; Steven Pyl^d ; Henk Vrielinck^c ; Freddy Callens^c ; Guy B. Marin^d ; Christophe Detavernier^c ; Paul V. Wiper^e ; Yaroslav Z. Khimyak^e ; Michel Waroquier^b ; Veronique Van Speybroeck^b ; ^{Veronique.VanSpeybroeck@UGent.be} ; Pascal Van Der Voort^a ; ^{Pascal.Vandervoort@ugent.be}
• 关键词：Metal Organic Frameworks ; Vanadium ; Oxidation catalysis ; DFT-D ; Epoxidation
• 刊名：Journal of Catalysis
• 出版年：2012
• 出版时间：January 2012
• 年：2012
• 卷：285
• 期：1
• 页码：196-207
• 全文大小：1545 K

文摘

A Metal Organic Framework, containing coordinatively saturated V^+IV sites linked together by terephthalic linkers (V-MIL-47), is evaluated as a catalyst in the epoxidation of cyclohexene. Different solvents and conditions are tested and compared. If the oxidant TBHP is dissolved in water, a significant leaching of V-species into the solution is observed, and also radical pathways are prominently operative leading to the formation of an adduct between the peroxide and cyclohexene. If, however, the oxidant is dissolved in decane, leaching is negligible and the structural integrity of the V-MIL-47 is maintained during successive runs. The selectivity toward the epoxide is very high in these circumstances. Extensive computational modeling is performed to show that several reaction cycles are possible. EPR and NMR measurements confirm that at least two parallel catalytic cycles are co-existing: one with V^+IV sites and one with pre-oxidized V^+V sites, and this is in complete agreement with the theoretical predictions.