Production of biodiesel from soybean oil on CaO/Al2O3 solid base catalysts

Authors:  Nagaraju Pasupulety, Kamalakar Gunda, Yuanqing Liu, Garry L. Rempel, Flora T.T. Ng

Abstract:
Transesterification of soybean oil was carried out over calcium oxide supported on Al₂O₃ as solid base catalysts. Solid base catalysts were synthesized by wet impregnation of CaO on acidic, basic and neutral Al₂O₃. Solid basic catalysts investigated in this study were characterized by BET surface area, XRD, FTIR, CO₂-TPD and TG/DTA techniques. Formation of fatty acid methyl esters (FAME) in this study was influenced by the nature of the catalyst prepared on different Al₂O₃ supports. CaO supported on neutral-Al₂O₃ exhibited higher FAME yield and the activation energy was determined to be 30.7 kJ/mol. The formation of the calcium diglyceroxide (CDG), on the surface of CaO supported on neutral Al₂O₃ was established by 13C NMR spectroscopy. The catalytic system (with CaO + CDG) on neutral Al2O3 showed higher activity in the transesterification of soybean oil. Among the catalysts studied the conversion of soybean oil to FAME formation was as follows: CaO/neutral-Al₂O₃ > CaO/basic-Al₂O₃ > CaO/acidic-Al₂O₃. The presence of CDG on neutral Al₂O₃ probably contributes to the higher activity. To our knowledge, this is the first report on identifying the formation of CDG on neutral Al₂O₃ during the production of biodiesel.

Key words:
Biodiesel
Calcium oxide
Calcium diglyceroxide
Impregnation
Transesterification

Published in: Applied catalysis A: General  (Volume 452, Pages 1-222, 15 February 2013)

Publisher: Elsevier

ISSN Information: 0926-860X

Production of biodiesel from soybean oil on CaO/Al2O3 solid base catalysts

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