Catalytic purification of fatty acid alkyl esters used in fuels

摘要

The process of this invention removes impurities from transesterification products comprising primarily fatty acid alkyl esters (FAAE) that are being processed for final fuel products, such as biodiesel. The inventive process is catalytic, and the resulting ester is suitable for use as biodiesel. Metal oxide and mixed metal oxide catalysts are particularly suitable. The invention is particularly suitable for treating fatty acid alkyl ester compositions comprising impurities such as glycerin, sterol glycosides, and/or triglyceride, diglyceride and/or monoglyceride. The invention is particularly useful in treating FAAE transesterification products made using homogeneous alkali catalysts. The treated ester exhibits improved performance under cold weather conditions, which can be measured by methods such as ASTM 7501 Cold Soak Filtration Test (CSFT).

主权项

1. A process for treating a fatty acid alkyl ester-containing stream comprising impurities, and at least ninety percent by weight fatty acid alkyl ester, and optionally alcohol, the process for treating the feed stream comprising:
(a) contacting the stream with a catalyst comprising metal oxide, wherein the metal is selected from the group of metals consisting of those in Groups 3, 4, 5, 13 and 14, and optionally, alcohol under catalytic conditions to convert the impurities in the stream to a product or by product, and (b) recovering a fatty acid alkyl ester stream having reduced amounts of impurities and having improved cold flow properties.