Submitted to: Journal of the Chemical Society Chemical Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/4/2007
Publication Date: 6/27/2007
Citation: Zafiropoulos, N.A., Ngo, H., Foglia, T.A., Samulski, E.T., Lin, W. 2007. Catalytic synthesis of biodiesel from high free fatty acid-containing feedstocks. Journal of the Chemical Society Chemical Communications. 3670-3672. Interpretive Summary: Biodiesel (BD) is a renewable and biodegradable diesel fuel made from vegetable oils and animal fats that runs in any conventional, unmodified diesel engine. BD typically is made by base-catalyzed transesterification of an oil or fat to simple fatty acids esters. The cost of the feedstock is the major factor in producing the fuel. Accordingly, yellow and brown greases, which are readily available low-cost materials, are attractive candidates for producing BD. The high free fatty acid (FFA) content of these feedstocks, however, makes it difficult to produce BD from them using conventional base-catalyzed methods. Typically, when using grease for BD production, an acid pretreatment step is used first to convert the FFA in the grease to BD prior to base-catalyzed conversion. This two-step process requires the use of excess base to neutralize the acid catalyst remaining in the pretreated grease, which increases production and waste treatment costs. Thus, there is a need to develop catalysts that can effectively convert the FFA in greases but be easily removed from the treated grease. This paper addresses this need in that it describes the synthesis of immobilized acid catalysts that are highly efficient in converting the FFA in grease to esters, and are then readily recovered for reuse.
Technical Abstract: Recyclable and reusable heterogeneous diarylammonium catalysts are highly effective in catalyzing the esterification of the free fatty acid (FFA) present in greases to methyl esters to reduce the FFA content from 12-40 wt% to 0.5 – 1 wt%. The resulting ester-glyceride mixture (pretreated grease) could then be readily converted to methyl esters by base-catalyzed transesterification.