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Catalytic reactions of methylcyclohexane (MCH), on partially reduced tungsten oxide(s)

Paper ID Volume ID Publish Year Pages File Format Full-Text
44087 46002 2007 7 PDF Available
Title
Catalytic reactions of methylcyclohexane (MCH), on partially reduced tungsten oxide(s)
Abstract

In situ XPS–UPS characterization of the reduction processes of bulk WO3 following the exposure of the sample to hydrogen at different temperatures up to 773 K enabled us to define the reduction conditions at which each of the different W2O5 and WO2 phases could be obtained. The reduction process takes place in the upper 10–15 atomic layers, most probably in a sandwich like atomic layer superposition structure of different tungsten oxide(s) at each set of reduction conditions. In order to define the nature of the chemical composition of the outermost surface layer; responsible for the chemical activity, the combination of XPS–UPS techniques proved to be valuable. The depth detection limit and relatively high collision cross section in the low binding energy valence electrons of UPS enabled us to clearly define the presence of WO2, with the bifunctional WO2(Hx)ac structure on its surface at reduction temperatures above 673 K. The presence of both, Brönsted and metal functions on the same surface of WO2(Hx)ac explains the catalytic behaviour of the sample towards the isomerization–dehydrogenation of methylcyclohexane.

Graphical abstractIn situ XPS–UPS characterization of bulk WO3 defines the reduction conditions to obtain different W2O5 and WO2 phases. UPS enabled us to clearly define the presence of WO2. The presence of both, Brönsted and metal functions in WO2(Hx)ac explains the catalytic behaviour of the sample towards the isomerization–dehydrogenation of methylcyclohexane. Figure: UPS of WO3 following reduction by H2: (a) as received and (b) 773 K for 2 h.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Methylcyclohexane; Isomerization; Dehydrogenation; Tungsten trioxide; Tungsten dioxide; XPS; UPS
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Catalytic reactions of methylcyclohexane (MCH), on partially reduced tungsten oxide(s)
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 318, 20 February 2007, Pages 227–233
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
Full-text PDF Download
Online Support
Any Questions? feel free to contact us