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Title: ESTERIFICATION OF OLEIC ACID IN SUPERCRITICAL CARBON DIOXIDE CATALYZED BY FUNCTIONALIZED MESOPOROUS SILICA AND AN IMMOBILIZED LIPASE

Author
item Jackson, Michael - Mike
item MBARAKA, ISA - IOWA ST UNIV, AMES, IA
item SHANKS, BRENT - IOWA ST UNIV, AMES, IA

Submitted to: Applied Catalysis A: General
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2006
Publication Date: 6/23/2006
Citation: Jackson, M.A., Mbaraka, I.K., Shanks, B.H. 2006. Esterification of oleic acid in supercritical carbon dioxide catalyzed by functionalized mesoporous silica and an immobilized lipase. Applied Catalysis A: Genera 310:48-53.

Interpretive Summary: Free fatty acids, such as oleic acid, can interfere with the easy conversion of vegetable oils and greases to biodiesel. A "one-step" method which would convert fatty acids to methyl esters would simplify the process and eliminate a costly clean-up step. Likewise, solid catalysts such as silicas, make collection of the biodiesel easier and cheaper. In this research effort, we demonstrated the utility of converting free fatty acids to methyl esters using carbon dioxide as a solvent. This environmentally benign solvent overcame some of the limitations associated with working in methanol as a solvent and allowed for the use of an enzyme to be used in the conversion.

Technical Abstract: Organosulfonic acid-functionalized mesoporous silicas were tested for catalytic performance in the esterification of oleic acid with methanol in flowing supercritical carbon dioxide. The energy of activation of the sulfonic acid catalysts was found to be about 42 kJ/mol and was shown to be independent of pore size. The catalytic activity of the functionalized silicas was compared to a standard acidic resin, Amberlyst 15, and to an immobilized lipase, Novozym 435. The most active catalyst was Novozym 435.