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Gas-phase selective oxidation of chloro- and methoxy-substituted toluenes on TiO2–Sepiolite supported vanadium oxides

Paper ID Volume ID Publish Year Pages File Format Full-Text
43176 45957 2009 8 PDF Available
Title
Gas-phase selective oxidation of chloro- and methoxy-substituted toluenes on TiO2–Sepiolite supported vanadium oxides
Abstract

Catalytic behaviour of vanadium oxide systems (5–20 wt.% V2O5) supported on TiO2–Sepiolite (with titania loading around the theoretical monolayer, 12 wt.%, 12Ti–Sep) and, as reference, on Sepiolite calcined (Sepc) in the p-substituted toluene derivatives selective oxidation was studied. In all the catalysts studied p-chloro (p-ClBA) and p-methoxybenzaldehyde (p-MeOBA) were the main products. The yields to benzaldehydes obtained with %V/12Ti–Sep are comparable with some of those reported in the literature under similar kinetically controlled experimental conditions (Sp-ClBA = 70% and X = 19% were obtained at 653 K on 20 V/12Ti–Sep). The activity for benzaldehyde derivatives formation of the %V/12Ti–Sep systems was superior to that exhibited by the %V/Sepc systems and in both series it notably increased when vanadium loading did. Furthermore, both p-substituents favourably influenced the partial oxidation of the methyl group to the corresponding aldehyde, whose formation at isoconversion is as follows: p-ClBA > p-MeOBA > BA. A concerted reaction mechanism in the oxidation of the toluenes to benzaldehydes on polymeric vanadia species has been proposed which is able to explain the toluene substituent effects as well as the activity of the catalysts.

Graphical abstractIn all the catalysts studied p-chloro (p-ClBA) and p-methoxybenzaldehyde (p-MeOBA) were the main products. (Sp-ClBA = 70% and X = 19% were obtained at 653 K on 20 V/12Ti–Sep). Both p-subtituents favourably influenced the partial oxidation of the methyl group (p-ClBA > p-MeOBA > BA). A concerted reaction mechanism in the oxidation of the toluenes to benzaldehydes on polymeric vanadia species has been proposed.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Supported vanadium oxide; Titania-coated Sepiolite; Gas-phase selective oxidation; 4-Chlorotoluene; 4-Methoxytoluene; 4-Chlorobenzaldehyde; 4-Methoxybenzaldehyde; XPS
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Gas-phase selective oxidation of chloro- and methoxy-substituted toluenes on TiO2–Sepiolite supported vanadium oxides
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 352, Issues 1–2, 15 January 2009, Pages 251–258
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Price was $35.95
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Price after discount Only $4.95
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