Dependence of n-Butane Activation on Active Site of Vanadium Phosphate Catalysts

The nature and the role of oxygen species and vanadium oxidation states on the activation of n-butane for selective oxidation to maleic anhydride were investigated. Bi-Fe doped and undoped vanadium phosphate catalysts were used a model catalyst. XRD revealed that Bi-Fe mixture dopants led to formati...

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Vydané v:Catalysis letters Ročník 130; číslo 3-4; s. 327 - 334
Hlavní autori: Taufiq-Yap, Y. H, Goh, C. K, Hutchings, G. J, Dummer, N, Bartley, J
Médium: Journal Article
Jazyk:English
Vydavateľské údaje: Boston Boston : Springer US 01.07.2009
Springer US
Springer
Springer Nature B.V
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ISSN:1011-372X, 1572-879X
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Shrnutí:The nature and the role of oxygen species and vanadium oxidation states on the activation of n-butane for selective oxidation to maleic anhydride were investigated. Bi-Fe doped and undoped vanadium phosphate catalysts were used a model catalyst. XRD revealed that Bi-Fe mixture dopants led to formation of αII-VOPO₄ phase together with (VO)₂P₂O₇ as a dominant phase when the materials were heated in n-butane/air to form the final catalysts. TPR analysis showed that the reduction behaviour of Bi-Fe doped catalysts was dominated by the reduction peak assigned to the reduction of V⁵⁺ species as compared to the undoped catalyst, which gave the reduction of V⁴⁺ as the major feature. An excess of the oxygen species (O²⁻) associated with V⁵⁺ in Bi-Fe doped catalysts improved the maleic anhydride selectivity but significantly lowering the rate of n-butane conversion. The reactive pairing of V⁴⁺-O⁻ was shown to be the centre for n-butane activation. It is proposed that the availability and appearance of active oxygen species (O⁻) on the surface of vanadium phosphate catalyst is the rate determining step of the overall reaction.
Bibliografia:http://dx.doi.org/10.1007/s10562-009-0003-2
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ISSN:1011-372X
1572-879X
DOI:10.1007/s10562-009-0003-2