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Evaluation of sulfated tin oxides in the esterification reaction of free fatty acids

Paper ID Volume ID Publish Year Pages File Format Full-Text
55681 47062 2011 7 PDF Available
Title
Evaluation of sulfated tin oxides in the esterification reaction of free fatty acids
Abstract

Sulfated tin oxides (SO42−/SnO2) with different SO42− contents (0.15, 0.3 and 0.45 wt%) were synthesized from hydroxylated tin oxide obtained by the precipitation method, followed by ion exchange of the OH groups with SO42− species using a sulfuric acid solution. In samples annealed at 673, 773 and 873 K the characterization of the solids was made by XRD, FT-IR and nitrogen adsorption. The strength and number of acid sites were determined by titration with n-butylamine using Hammett indicators an acid strength of Ho < −8.2 was found. Sulfated tin oxides were tested in the esterification reaction of free fatty acids with ethanol (molar ratio 1:10), at 353 K. XRD profiles showed that the sulfating inhibits the SnO2 crystal growth. The SO4 species remained strongly bonded at the SnO2 surface stabilizing its crystallite size against sintering and it acts as a structure porogen director mediating nanoparticle growth and assembly yielding a mesostructured form of SnO2 with wormhole morphology and high thermal stability. The conversion of oleic acid increases with the increase of surface acidity showing a maximum when the sulfate content and calcination temperature were 0.3 wt% and 773 K, respectively. Regeneration through heating the SO42−/SnO2 with the highest activity for 4 h allows it for reuse without losing of its catalytic activity.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (202 K)Download as PowerPoint slideHighlights► SO42−/SnO2 catalysts were evaluated in the esterification of free fatty acids. ► XRD showed that sulfating avoids the SnO2 crystallite size growth. ► Higher acidity was obtained on the SO42−/SnO2 catalysts. ► The conversion of oleic acid increases with the increase of surface acidity. ► The used SO42−/SnO2 catalysts recuperate in a high amount the initial activity.

Keywords
XRD sulfated tin oxides; Solid superacid; Acidity of Hammett; Esterification of free fatty acids; Sulfated tin oxides acidity
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Evaluation of sulfated tin oxides in the esterification reaction of free fatty acids
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Today - Volume 172, Issue 1, 25 August 2011, Pages 34–40
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