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Redox properties of H3PMoxW12−xO40 and H6P2MoxW18−xO62 heteropolyacid catalysts and their catalytic activity for benzyl alcohol oxidation

Paper ID Volume ID Publish Year Pages File Format Full-Text
42826 45942 2008 7 PDF Available
Title
Redox properties of H3PMoxW12−xO40 and H6P2MoxW18−xO62 heteropolyacid catalysts and their catalytic activity for benzyl alcohol oxidation
Abstract

Reduction potentials of H3PMoxW12−xO40 (x = 0, 3, 6, 9, and 12) Keggin heteropolyacid (HPA) and H6P2MoxW18−xO62 (x = 0, 3, 9, 15, and 18) Wells-Dawson HPA catalysts were measured by an electrochemical method in solution. UV–visible spectra of H3PMoxW12−xO40 and H6P2MoxW18−xO62 catalysts in solution were then obtained in order to explore the reduction potentials of the HPA catalysts. Reduction potentials increased and UV–visible absorption edge energies shifted to lower values with increasing molybdenum substitution in both families of H3PMoxW12−xO40 and H6P2MoxW18−xO62 catalysts. It was revealed that the lower absorption edge energy corresponded to the higher reduction potential of the HPA catalyst. In order to correlate the redox property (reduction potential and absorption edge energy) with the catalytic oxidation activity of H3PMoxW12−xO40 and H6P2MoxW18−xO62 catalysts, vapor-phase oxidation of benzyl alcohol was carried out as a model reaction. Yield for benzaldehyde increased with increasing reduction potential and with decreasing absorption edge energy of the HPA catalyst, regardless of the identity of HPA catalyst (without HPA structural sensitivity). The absorption edge energies measured by UV–visible spectroscopy could be utilized as a correlating parameter for the reduction potentials (oxidizing powers) of H3PMoxW12−xO40 and H6P2MoxW18−xO62 catalysts, and furthermore, as a probe of oxidation catalysis of the HPA catalysts.

Graphical abstractReduction potentials and UV–visible absorption edge energies of H3PMoxW12−xO40 Keggin heteropolyacid (HPA) and H6P2MoxW18−xO62 Wells-Dawson HPA catalysts were measured to probe their oxidation catalysis for benzyl alcohol oxidation. Yield for benzaldehyde increased with increasing reduction potential and with decreasing absorption edge energy of the HPA catalyst, regardless of the identity of the catalyst.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Heteropolyacid catalyst; Reduction potential; UV–visible absorption edge energy; Benzyl alcohol oxidation
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Redox properties of H3PMoxW12−xO40 and H6P2MoxW18−xO62 heteropolyacid catalysts and their catalytic activity for benzyl alcohol oxidation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 349, Issues 1–2, 31 October 2008, Pages 222–228
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
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