BayFAME®

The Chemical Reaction

Free fatty acids in biodiesel feedstocks can be converted into fatty acid methyl ester (FAME) by esterification with methanol. This reaction is typically catalyzed by an acid catalyst, such as sulfuric acid. However, the application of strong acidic homogeneous catalysts like H₂SO₄ requires a significant extra effort in terms of materials of construction and safety compared to a conventional biodiesel plant. These restrictions are resolved by the Bayer Technology Services continuous free fatty acid esterification process, which includes an optimized process design for the application of the heterogeneous esterification with AMBERLYST™ BD20 catalyst from Rohm and Haas. As the esterification of free fatty acids is equilibrium limited at relatively low FFA conversions, the driving force to achieve complete FFA removal needs to be increased by using methanol in excess to the stoichiometric requirement. This is combined with a multi-stage reactor configuration with an inter-stage removal of the by-product water, which offers a further shift of the thermodynamic equilibrium towards complete conversion of even high FFA concentrations in the feedstock.