| 摘要 |
<p>Fatty acid alkyl esters are produced by catalytic transesterification of natural fats and oils containing free fatty acids. In a preliminary esterifying step, the free fatty acids present are reacted with a C1-C4 alkanol (e.g., methanol) in the presence of an acidic esterification catalyst, at a temperature of about 50 DEG to 120 DEG C. and at substantially atmospheric pressure. The resulting reaction mixture is allowed to separate into two phases: (1) an alcohol phase containing the acidic esterification catalyst and part of the water of reaction and (2) an oil phase. These phases separately recovered. The oil phase is then extracted with an immiscible extractant, preferably comprising a mixture of glycerol and methanol, to remove residual water of reaction. In the final step the extracted oil phase is transesterified with a C1-C4 alkanol, e.g. methanol, in the presence of an aklali catalyst and at substantially atmospheric pressure.</p> |
