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Styrene epoxidation over V-SBA-15 with alkaline-earth metal ion promotion under photo-assisted conditions

Paper ID Volume ID Publish Year Pages File Format Full-Text
41093 45877 2012 10 PDF Available
Title
Styrene epoxidation over V-SBA-15 with alkaline-earth metal ion promotion under photo-assisted conditions
Abstract

The photo-assisted epoxidation of styrene over V/SBA-15 modified by alkaline-earth metal ions was investigated with hydrogen peroxide at room temperature. The results indicated that the isolated VO4 tetrahedron dispersed on the SiO2 was the photo-assisted catalytic active site for the formation of styrene oxide, while V5+ polymer species in V/SBA-15 with highly loaded V species caused deep oxidation of styrene oxide. Among the catalysts modified by alkaline-earth metal ions, Mg–V/SBA-15 displayed the best catalytic performance. It was probably due to the fact that the metallic character of Mg was weaker in alkaline-earth metals, so it was easier to disperse V5+ polymer species and the dispersion effect was especially obvious in the comparatively high loading weight of vanadium oxide. Moreover, addition of alkaline-earth metals decreased the acidic sites of V/SBA-15, inhibiting the ring-opening reaction on which the deep oxidation occurred. The structures of all catalysts were thoroughly investigated using different characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), NH3-temperature programmed desorption (TPD), H2 temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS), etc. A possible catalytic mechanism was proposed.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (81 K)Download as PowerPoint slideHighlights► V-SBA-15 with alkaline-earth metal ion was synthesized. ► Catalysts with low acidic sites avoided the ring opening reaction. ► Addition of alkaline-earth metals favor of dispersion of V5+ species. ► Possible mechanism for styrene epoxidation was discussed.

Keywords
V/SBA-15; Alkaline-earth metal promotion; Styrene; Photo-assisted epoxidation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 413–414, 31 January 2012, Pages 52–61
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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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