Sulfonic acid functionalized mesoporous SBA-15 catalysts for biodiesel production

Authors: Donghua Zuo, James Lane, Dan Culy, Michael Schultz, Allison Pullar, Michael Waxman

Abstract:
Sulfonic acid functionalized mesoporous SBA-15 catalysts have been studied in the microwave-assisted transesterification of soybean oil with 1-butanol in order to produce low freezing point biodiesel. Smallangle powder XRD and nitrogen adsorption analysis revealed the formation of mesoporous materials with high surface area and uniform porosity. Catalytic activity was found to be largely dependent on the acid strength rather than the number of acid sites. Propyl-SO₃H and arene-SO₃H functionalized SBA-15 catalysts showed high activity and stability in transesterification reactions whereas perfluoro-SO₃H functionalized SBA-15 catalyst exhibited a complete loss of activity after recycling due to complete leaching of perfluoro-SO₃H groups in the reaction medium. The results over arene-SO₃H functionalized catalysts showed thatthe optimal loading of arene-SO₃H groups is approximately 15% (molar percent of functional group to total silicon) and the optimal oil to alcohol molar ratio is 1:6. Increases in catalyst to oil weight ratio and reaction temperature significantly enhance the reaction rates. Simultaneous transesterification and esterification of soybean oil with up to 20 wt% oleic acid over arene-SO₃H functionalized catalyst indicated that this catalyst could be a promising candidate for processing low quality feedstocks containing high fraction of free fatty acids. Further modification of Ar-SO₃H SBA-15 catalyst with hydrophobic groups did not significantly improve its catalytic performance.

Keywords:
Mesoporous SBA-15 catalysts
Organosulfonic acid functionalization
Biodiesel
Transesterification
Esterification

Published in: Applied catalysis B: Environmental  (Volume 129, Pages 1-614, 17 January 2013)

Publisher: Elsevier  

ISSN Information: 0926-3373

Sulfonic acid functionalized mesoporous SBA-15 catalysts for biodiesel production

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