METHOD FOR PRODUCING FATTY ACID LOWER ALKYL ESTER FOR GAS OIL SUBSTITUTE FUEL

摘要

PROBLEM TO BE SOLVED: To provide a method by which a high-purity fatty acid lower alkyl ester suitably usable as a gas oil substitute fuel is stably produced from a raw material containing an animal or vegetable oil and fat in high yield. SOLUTION: The method for producing the fatty acid lower alkyl ester comprises the following steps: (A) an esterification step of esterifying a fatty acid in the raw material with a lower alkyl alcohol using a cation exchange resin and affording a reaction mixture containing an ester mixed oil having≤2 acid value; (B) a transesterification step having a first step of carrying out transesterification of an oil and fat in the ester mixed oil with the lower alkyl alcohol while regulating the amount of an alkali catalyst according to the acid value; (R) a recycling step of carrying out acid decomposition of a soap formed as a by-product in the step (B) under conditions of pH2-5, affording a fatty acid and returning the fatty acid; and (C) a distillation step having a vacuum distillation step of distilling the fatty acid lower alkyl ester from the oily phase obtained in the transesterification step (B). COPYRIGHT: (C)2007,JPO&INPIT