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Selective nitration of phenol over nanosized tungsten oxide supported on sulfated SnO2 as a solid acid catalyst

Paper ID Volume ID Publish Year Pages File Format Full-Text
42849 45943 2009 8 PDF Available
Title
Selective nitration of phenol over nanosized tungsten oxide supported on sulfated SnO2 as a solid acid catalyst
Abstract

WO3 loaded on nano-crystalline sulfated tin oxide solid acid catalyst has been synthesized and studied for selective nitration of phenol. The catalysts were characterized by various analytical and spectroscopic techniques including thermal analysis, powder X-ray diffraction (XRD), N2 adsorption and FTIR spectra. The surface acidity was measured by no aqueous potentiometric titration and FTIR spectra of chemically adsorbed pyridine.The acidity measurements showed that the samples contain both Lewis and Brønsted acid sites; moreover, the total acidity increases with the rise of WO3 content up to 30 wt.% (monolayer coverage) and decreases thereafter. The results also showed the possibilities of interaction of WO3 with sulfate and/or SnO2 surface that led to some changes in the surface structure of the catalyst. The catalytic activity well correlates with Brønsted acid sites of these catalysts. The effect of the reaction parameters, i.e. reactants molar ratio, reaction temperature and time was also investigated. The catalyst was reused for five times with excellent percentage conversion and high selectivity towards ortho isomer. The possible reaction mechanism for the formation of ortho and para isomers was also discussed.

Graphical abstractWO3 loaded on nano-crystalline sulfated tin oxide solid acid catalyst has been synthesized and studied for selective nitration of phenol. The catalysts were characterized by various analytical and spectroscopic techniques including thermal analysis, powder X-ray diffraction (XRD), N2 adsorption and FTIR spectra. The surface acidity was measured by no aqueous potentiometric titration and FTIR spectra of chemically adsorbed pyridine.The acidity measurements showed that the samples contain both Lewis and Brønsted acid sites; moreover, the total acidity increases with the rise of WO3 content up to 30 wt.% (monolayer coverage) and decreases thereafter. The results also showed the possibilities of interaction of WO3 with sulfate and/or SnO2 surface that led to some changes in the surface structure of the catalyst. The catalytic activity well correlates with Brønsted acid sites of these catalysts. The effect of the reaction parameters, i.e. reactants molar ratio, reaction temperature and time was also investigated. The catalyst was reused for five times with excellent percentage conversion and high selectivity towards ortho isomer. The possible reaction mechanism for the formation of ortho and para isomers was also discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Sulfated tin oxide; WO3; Surface acidity; Nitration reaction; ortho and para Nitrophenol; Reaction mechanism
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Selective nitration of phenol over nanosized tungsten oxide supported on sulfated SnO2 as a solid acid catalyst
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 354, Issues 1–2, 15 February 2009, Pages 153–160
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
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Full-text PDF Download
Online Support
Any Questions? feel free to contact us