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Selective oxidation of styrene to benzaldehyde catalyzed by Schiff base-modified ordered mesoporous silica materials impregnated with the transition metal-monosubstituted Keggin-type polyoxometalates

Paper ID Volume ID Publish Year Pages File Format Full-Text
42882 45944 2009 10 PDF Available
Title
Selective oxidation of styrene to benzaldehyde catalyzed by Schiff base-modified ordered mesoporous silica materials impregnated with the transition metal-monosubstituted Keggin-type polyoxometalates
Abstract

A series of Schiff base-modified ordered mesoporous silica materials impregnated with the transition metal-monosubstituted Keggin-type polyoxometalates (mono-TMSPs), K10−nXn+MW11O39-Schiff-SBA-15, (X = P/Si, M = Co/Ni/Cu/Mn), was prepared using successive grafting procedures of SBA-15 silica with 3-aminopropyl-trimethoxysilane, benzaldehyde, and mono-TMSP. The composite materials were well-characterized by spectroscopy methods, X-ray diffraction analysis, transmission electron microscopy, and nitrogen sorption analysis to confirm the structure integrities of the Keggin unit and Schiff base ligand after the incorporation, to evidence formation of the coordination binding between the starting Keggin units and the Schiff base-modified silica matrix, and to investigate the morphology and surface textural properties of the composite catalysts. These materials were subsequently utilized as efficient and selective catalysts in the reaction of oxidation of styrene to benzaldehyde using H2O2 as an oxidant. For comparison, an amine-modified SBA-15 silica material impregnated with mono-TMSP (K10−nXn+MW11O39-NH2-SBA-15) and the neat Keggin unit (K10−n[Xn+M(H2O)W11O39]) was also tested. The influences of key reaction parameters, including the molar ratios of H2O2 to styrene, compositions and loadings of the neat mono-TMSPs, solvents, the catalyst amount, and reaction temperatures on the reactivity and selectivity, were also studied. Finally, the reusability of the catalysts was evaluated.

Graphical abstractSchiff base-modified ordered mesoporous silica materials impregnated with the transition metal monosubstituted Keggin-type polyoxometalates, K10−nXn+MW11O39-Schiff-SBA-15, were prepared via the coordination of transition metal centers in the Keggin units with nitrogen atoms of Schiff base modified silica supports. The composites exhibited high catalytic reactivity, selectivity, and stability toward the reaction of oxidation of styrene to produce benzaldehyde by H2O2.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Selective oxidation; Benzaldehyde; Supported polyoxometalate; Ordered mesoporous material; Schiff base
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Selective oxidation of styrene to benzaldehyde catalyzed by Schiff base-modified ordered mesoporous silica materials impregnated with the transition metal-monosubstituted Keggin-type polyoxometalates
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 364, Issues 1–2, 31 July 2009, Pages 211–220
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
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Any Questions? feel free to contact us