METHOD FOR PRODUCING BIOFUEL USING CIRCULATION TYPE REACTION APPARATUS

To provide a method for producing a biofuel comprising reacting a raw oil containing free fatty acids with a lower alcohol in presence of a solid acid catalyst, that can increase a conversion rate of free fatty acids by using a circulation type reaction apparatus, suppress the conversion rate of triglyceride low, and enable mass production of the biofuel suitable for a diesel engine.SOLUTION: The method for producing the biofuel comprises using a catalyst selected from SiO2/Al2O3 based solid acid catalyst, SiO2/Al2O3 based solid acid catalyst with some aluminum introduced into mesoporous silica and Al2O3/B2O3 based solid acid catalyst, as a solid acid catalyst, wherein a mass ratio of the lower alcohol to the raw oil is 0.12 to 0.8, a reaction temperature is 170°C to 300°C, and liquid space velocity (LHSV) is 0.5(h-1) to 6(h-1).SELECTED DRAWING: Figure 1 【課題】固体酸触媒の存在下で遊離脂肪酸を含む原料油と低級アルコールを反応させるバイオ燃料の製造方法において、流動式反応装置を用いて遊離脂肪酸の転化率が高く、トリグリセライドの転化率が低く抑えられて、ディーゼルエンジンに適したバイオ燃料の量産を可能にする。【解決手段】固体酸触媒としてSiO2/Al2O3系固体酸触媒、メソポーラスシリカにアルミニウムを一部導入したSiO2/Al2O3系固体酸触媒、Al2O3/B2O3系固体酸触媒から選択された触媒を使用し、低級アルコールと原料油の質量比０．１2〜０．８、反応温度として１７０℃〜３００℃、液空間速度（LHSV）0．5(h-1)〜6(h-1)で行わせるバイオ燃料の製造方法。【選択図】図１