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Transesterification of rapeseed oil with ethanol: I. Catalysis with homogeneous Keggin heteropolyacids

Paper ID Volume ID Publish Year Pages File Format Full-Text
43449 45970 2007 8 PDF Available
Title
Transesterification of rapeseed oil with ethanol: I. Catalysis with homogeneous Keggin heteropolyacids
Abstract

Heteropolyacids (HPA) with Keggin structure were evaluated as homogeneous Br∅nsted acid catalysts in the reaction of rapeseed oil transesterification with methanol and ethanol at 358 K and atmospheric pressure. Rapeseed oil transesterification with ethanol over anhydrous Keggin HPAs leads to higher conversion level than H2SO4 compared at equivalent H+ concentration and H2O/H+ molar ratio. By contrast, Phosphoric acid, a quite weaker mineral acid, structurally close to H3PW12O40, is not operative under similar conditions. This demonstrates the advantages of strong Br∅nsted acids in vegetable oil transesterification with ethanol in mild conditions. It is worth noticing that differences in acid strength between anhydrous Keggin heteropolyacids, H3PW12O40, H4SiW12O40, H3PMo12O40, H4SiMo12O40, measured by calorimetry, did not correlate simply the catalytic activity. Indeed, the proton solvation with water molecule was shown to be a crucial parameter. Then, Mo samples exhibited higher activities due to their ability to lose crystallization water at lower temperatures compared to W samples. Finally, it was shown that higher transesterification rates were obtained with ethanol than methanol in presence of HPA.

Graphical abstractKeggin heteropolyacids were evaluated as homogeneous Br∅nsted acid catalysts in the reaction of rapeseed oil transesterification with ethanol at 358 K and atmospheric pressure. Anhydrous Keggin HPAs exhibited higher catalytic performance than H2SO4 and H3PO4 compared at equivalent H+ concentration and H2O/H+ molar ratio in relation with their higher Br∅nsted acid strength. Figure optionsDownload full-size imageDownload as PowerPoint slide

Keywords
Biodiesel; Transesterification; Rapeseed oil; Vegetable oil; Heteropolyacids
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Transesterification of rapeseed oil with ethanol: I. Catalysis with homogeneous Keggin heteropolyacids
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 330, 10 October 2007, Pages 69–76
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