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Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide: 1. Selectivity enhancement by aliphatic alcohols

Paper ID Volume ID Publish Year Pages File Format Full-Text
42821 45942 2008 7 PDF Available
Title
Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide: 1. Selectivity enhancement by aliphatic alcohols
Abstract

Oxygenated aqueous suspensions of home-prepared (HP) and commercial TiO2 catalysts were used in a batch photoreactor for carrying out the oxidation of benzyl alcohol (BA) and 4-methoxybenzyl alcohol (MBA) under different operative conditions. HP catalysts were synthesized from TiCl4 and underwent a hydrolysis treatment of different times under mild conditions. The textural characterization of catalysts was carried out with XRD, SEM observations, BET surface area and porosity measurements. For both alcohols the main oxidation products were the corresponding aromatic aldehydes and CO2. The HP catalysts exhibited selectivity values towards the aldehyde production up to 28% (BA conversion: 50%) and 41% (MBA conversion: 65%), about four times higher than those of commercial TiO2. The addition of an aliphatic alcohol (methanol, ethanol, 2-propanol or tert-butanol) in small amounts with respect to water decreased the overall oxidation rate of aromatic alcohols but enhanced the selectivity for aldehyde formation up to 1.5 times. The reactivity results suggest that: (i) the aromatic alcohol molecules interact with the TiO2 surface in different ways that eventually determine two parallel reaction pathways (partial oxidation or mineralization); (ii) the aliphatic alcohols preferentially compete with aromatic alcohols for the mineralizing pathway.

Graphical abstractHome-prepared (ex TiCl4) and commercial TiO2 catalysts were used for carrying out the oxidation of benzyl alcohol and 4-methoxybenzyl alcohol. The HP catalysts exhibited selectivity towards the aldehyde up to four times higher than those of commercial TiO2. The addition of an aliphatic alcohol in small amounts enhanced the selectivity for aldehyde formation up to 1.5 times. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Photocatalysis; TiO2; Aromatic alcohols; Aliphatic alcohol; Selective oxidation
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Photocatalytic oxidation of aromatic alcohols to aldehydes in aqueous suspension of home-prepared titanium dioxide: 1. Selectivity enhancement by aliphatic alcohols
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 349, Issues 1–2, 31 October 2008, Pages 182–188
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