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Supported niobium catalysts for methanol dehydration to dimethyl ether: FTIR studies of acid properties

Paper ID Volume ID Publish Year Pages File Format Full-Text
55166 47042 2012 8 PDF Available
Title
Supported niobium catalysts for methanol dehydration to dimethyl ether: FTIR studies of acid properties
Abstract

A series of NbOx/TiO2 catalysts (0.9–9.0 at Nb nm−2) was prepared by incipient wetness impregnation of niobium (V) oxalate aqueous solutions on TiO2. Spectroscopic data reveal that NbOx phase is highly dispersed and relatively large Nb2O5 crystallites are not detected; highly distorted NbO6 octahedral structures are exclusively identified by Raman spectroscopy. Surface acidity measurements by NH3-temperature-programmed desorption experiments indicate that the overall number of Lewis acid sites in the solids decreases with Nb-loading, although their strength follows the opposite trend. A minor fraction of Brønsted acid sites is also detected for the sample with the highest Nb surface coverage used here (9.0 at Nb nm−2). The catalytic activity of NbOx/TiO2 in methanol dehydration to dimethyl ether is found to be determined mainly by the strength of the acid sites and the presence of Brønsted acid sites, being more active those catalysts with stronger acid sites and with a higher number of Brønsted acid sites.

Graphical abstractThe catalytic activity in CH3OH dehydration reaction increases with Nb content because of the higher strength of Lewis acid sites and the formation of additional Brønsted acid sites.Figure optionsDownload full-size imageDownload high-quality image (85 K)Download as PowerPoint slideHighlights► NbOx/TiO2 are active and selective catalysts for methanol dehydration to DME. ► Stronger Lewis and Brønsted acid sites are formed upon increasing surface Nb density. ► Methanol dehydration rates increase with the strength of acid sites.

Keywords
Niobium oxides; Brønsted; Lewis; Acid sites; Methanol; Dimethyl ether
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Supported niobium catalysts for methanol dehydration to dimethyl ether: FTIR studies of acid properties
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 192, Issue 1, 30 September 2012, Pages 136–143
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