Efficient Two-Step Synthesis of Biodiesel from Greases

• DOI: 10.1021/ef700343b
• Publication Date: 2007-11-19T06:00:32Z
• Authors: Helen L. Ngo; Nicholas A. Zafir...; Thomas A. Foglia; Edward T. Samulski; Wenbin Lin
• Keywords: 0202 electrical engineering, electronic engineering, information engineering; 02 engineering and technology; 7. Clean energy

Biodiesel (BD) is an alternative diesel fuel derived from both vegetable oils and animal fats. Currently, most BD is made by alkali-catalyzed transesterification of a refined oil or fat, the cost of which is the major expenditure in producing BD. Yellow and brown greases are readily available renewable fats that are less expensive and hence represent attractive feedstocks for the production of BD. The high free fatty acid (FFA) content of these feedstocks, however, makes it difficult to produce BD using base-catalyzed transesterification. In this paper, we report the use of a series of diarylammonium catalysts that are highly effective in catalyzing the esterification of the FFA present in greases (12–40 wt % FFA). At a catalyst loading of 2–3 mol %, high conversions of FFA to esters (95−99%) were achieved by treating the greases with 5–20 equiv of methanol at 95 °C for 2 h. The treated greases had a final FFA content of 0.5–1 wt %. We also incorporated these diarylammonium catalysts into insoluble porous...