Abstract: Provided is a process for producing a fatty acid alkylester through a transesterification of triglyceride contained in a fat and oil by causing the fat and oil and an alcohol to react with each other. In this process, the reaction is performed in an atmosphere in which the alcohol is in super-critical state in the absence of a metal alkali catalyst and an acid catalyst. This makes it possible to eliminate a pre-treatment process for esterifying free fatty acids contained in the fat and oil and, in addition, to eliminate or simplify recovering and refining processes of the reaction product by suppressing the by-production of a fatty acid soap.

Abstract: In a method of producing a fatty acid lower alkylester according to the invention, a fat & oil and a lower alcohol are caused to react with each other in the presence of a catalyst, in which triglyceride contained in the fat & oil undergoes a transesterification. The catalyst to be used in the reaction is a solid basic catalyst consisting essentially of a potassium compound and iron oxide, of a calcium compound and iron oxide, or of a potassium compound and zirconium oxide. It is possible to produce the fatty acid lower alkylester at a high reaction efficiency by this method as well as to simplify or eliminate the need of catalyst separation and recovery processes.

Abstract: A production method of diesel fuel oil from waste oil, in which a vegetable diesel fuel oil can be obtained by utilizing as a raw material a waste edible oil dumped from restaurant, food industry, home, etc. and scarcely utilized.