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Synthesis of biodiesel over zirconia-supported isopoly and heteropoly tungstate catalysts

Paper ID Volume ID Publish Year Pages File Format Full-Text
52239 46867 2008 7 PDF Available
Title
Synthesis of biodiesel over zirconia-supported isopoly and heteropoly tungstate catalysts
Abstract

The liquid-phase synthesis of biodiesel by transesterification of sunflower oil with methanol is carried out by using zirconia-supported isopoly and heteropoly tungstates (HPAs) as catalysts. The isopoly and heteropoly tungstate catalysts were prepared by suspending zirconium oxyhydroxide in water/methanol solution of ammonium metatungstate/silicotungstic acid, phosphotungstic acid (WO3/HPA loading, 15%) followed by drying and calcination at 750 °C. The catalysts were characterized by XRD, Raman spectroscopy, IR spectroscopy, NH3-TPD and FTIR pyridine adsorption spectroscopy. XRD results indicate that the presence of isopoly and heteropoly tungstates stabilizes ZrO2 in tetragonal phase. Raman and IR spectra of the catalysts show that tungstate species exist as zirconia-anchored octahedral mono-oxotungstate. The acidity measurements by NH3-TPD and FTIR pyridine adsorption spectroscopy show that zirconia-supported phosphotungstate has the highest total acidity and zirconia-supported isopoly tungstate has the highest Brønsted acidity. The zirconia-supported isopoly tungstate shows superior catalytic performance compared to zirconia-supported heteropoly tungstate catalysts. Under the reaction conditions of 200 °C and methanol/oil molar ratio 15, 15% WO3/ZrO2 calcined at 750 °C gave 97% conversion of oil. This catalyst also efficiently catalyzes methanolysis of other vegetable oils like mustard oil and sesame oil. The deactivated catalyst could be regenerated by calcination without appreciable loss in activity.

Keywords
Zirconia; Tungsten oxide; Silicotungstic acid; Phosphotungstic acid; Transesterification; Biodiesel
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Synthesis of biodiesel over zirconia-supported isopoly and heteropoly tungstate catalysts
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Publisher
Database: Elsevier - ScienceDirect
Journal: Catalysis Communications - Volume 9, Issue 5, 20 March 2008, Pages 696–702
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