fulltext.study @t Gmail

Catalytic fluorination of 2-chloropyridine over metal oxide catalysts in gas phase in the presence of HF

Paper ID Volume ID Publish Year Pages File Format Full-Text
41103 45877 2012 8 PDF Available
Title
Catalytic fluorination of 2-chloropyridine over metal oxide catalysts in gas phase in the presence of HF
Abstract

The fluorination of 2-chloropyridine to produce selectively 2-fluoropyrydine by Cl/F exchange at 300 or 380 °C with HF as the fluorinating agent and a metal oxide as precursor of catalyst was investigated. The influence of the activation step under HF gas on the structural, microstructural and physico-chemical properties of various oxides such as MgO, CeO2, Ce0.5Zr0.5O2, LaFeO3, Cr2O3, were studied. This activation step by HF led to the formation of the corresponding fluorides and/or oxyfluorides materials which were the active catalysts for the Cl/F exchanges. Moreover, this activation step modified strongly the initial properties of the starting materials. This corresponded to a strong decrease of the initial specific surface area and of the basic properties. In the same time, an increase of Lewis acid properties measured by FTIR with pyridine as probe molecule was noticed. MgO, which was initially the most basic oxide studied was also the most active for the fluorination of the 2-chloropyridine after its transformation into fluoride solid which was the active catalyst. This could be due to a lower strength Lewis acidity of the active sites formed by the activation step by HF directly correlated to the basic properties of the initial oxides. A mechanism of the 2-chloropyridine fluorination involving Lewis acid unsaturated metal site was proposed.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (58 K)Download as PowerPoint slideHighlights► Heterogeneous catalytic process with HF gas used to prepare 2-fluoropyridine. ► Initial basic oxides used as precursors of catalysts for a Cl/F exchange reaction to form 2-chloropyridine. ► Activation by HF gas of basic oxide leading to the formation of fluorides or oxyfluorides with a moderate Lewis acidity. ► Fluorination of 2-chloropyridine involving unsatured metals as active sites with a moderate Lewis acidity.

Keywords
Basic metal oxides; Fluoride metal catalyst; Fluorination; 2-Chloropyridine; 2-Fluoropyridine
First Page Preview
Catalytic fluorination of 2-chloropyridine over metal oxide catalysts in gas phase in the presence of HF
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
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volumes 413–414, 31 January 2012, Pages 149–156
Authors
, , , ,
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