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Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home prepared titanium dioxide: 2. Intrinsic and surface features of catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
42822 45942 2008 9 PDF Available
Title
Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home prepared titanium dioxide: 2. Intrinsic and surface features of catalysts
Abstract

In this paper some intrinsic electronic properties of home prepared (HP) TiO2 catalysts were investigated by diffuse reflectance spectroscopy and quasi-Fermi level measurements. These powders were used for carrying out the photocatalytic oxidation of benzyl alcohol to benzaldehyde and CO2 in water; the selectivity for aldehyde formation was enhanced by the addition of small amounts of ethanol, a typical hole trap. The values of band gap, valence band and conduction band edges are almost identical for all the HP samples in which anatase phase is predominant, whereas appreciable differences can be noticed for an HP sample containing high amount of rutile phase. A comparative ATR-FTIR study of the HP catalyst showing the highest selectivity and the commercial titania showing the highest activity towards benzyl alcohol oxidation (Degussa P25 TiO2) was carried out. The ATR-FTIR results indicate that HP and Degussa P25 surfaces show a very dissimilar hydrophilicity and different ability for adsorbing the organic compounds deriving from benzyl alcohol photocatalytic oxidation. Results show moreover that the improved selectivity to aldehyde by adding ethanol is due to competition between the substrate and the hole trap for adsorption on reactive sites.

Graphical abstractHome prepared TiO2 powders were used for carrying out the photocatalytic oxidation of benzyl alcohol in water, in the presence of ethanol. Catalysts characterization was carried out through XRD, SEM, TG, BET and porosity measurements. Diffuse reflectance spectroscopy and quasi-Fermi level measurements were also performed. An ATR-FTIR study of catalysts showed that HP and Degussa P25 surfaces hold very different hydrophilicity and ability for adsorbing the intermediates deriving from benzyl alcohol oxidation. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Photocatalysis; TiO2; In situ ATR-FTIR analysis; Aromatic alcohols; Selective oxidation; Aliphatic alcohol
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Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home prepared titanium dioxide: 2. Intrinsic and surface features of catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 349, Issues 1–2, 31 October 2008, Pages 189–197
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
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Any Questions? feel free to contact us