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Selective oxidation of phenol and benzoic acid in water via home-prepared TiO2 photocatalysts: Distribution of hydroxylation products

Paper ID Volume ID Publish Year Pages File Format Full-Text
40776 45865 2012 11 PDF Available
Title
Selective oxidation of phenol and benzoic acid in water via home-prepared TiO2 photocatalysts: Distribution of hydroxylation products
Abstract

The hydroxylation of phenol (a substrate containing an electron donor group) and of benzoic acid (a substrate containing an electron withdrawing group) has been carried out by the photocatalytic method in aqueous suspensions containing commercial or home prepared TiO2 samples. The aim of the work was to study the distribution of hydroxylation products when different photocatalysts were used and to correlate the selectivity to some physico-chemical features of the powders. The samples were characterized by X-ray diffraction, thermogravimetry, determination of crystalline phase percentage, specific surface area and zero charge point. The photoreactivity results indicate that the products of the primary oxidation of phenol are the ortho- and para-mono-hydroxy derivatives while those of benzoic acid are all the mono-hydroxy derivatives independently of the catalyst. The selectivity toward mono-hydroxy derivatives shows a strong dependence on catalyst hydroxylation and crystallinity degrees: the highest selectivity values were obtained by using the commercial samples that resulted the least hydroxylated and the most crystalline ones. A kinetic model, taking into account the mineralization and the partial oxidation reaction routes, is proposed by using the Langmuir–Hinshelwood model.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (236 K)Download as PowerPoint slideHighlights► Photocatalytic hydroxylation of phenol and benzoic acid was carried out in the presence of TiO2 catalysts. ► Distribution of hydroxylation products was correlated with some catalysts features. ► Selectivity depended on photocatalyst hydroxylation degree. ► Satisfactory fitting of experimental data to the Langmuir–Hinshelwood kinetic model was found.

Keywords
Selective hydroxylation; Product distribution; Benzoic acid; Phenol; Heterogeneous photocatalysis; Reaction pathways; Kinetics; TiO2
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Selective oxidation of phenol and benzoic acid in water via home-prepared TiO2 photocatalysts: Distribution of hydroxylation products
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 441–442, 28 October 2012, Pages 79–89
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