Abstract: The present invention provides a method for producing a biofuel that allows an animal/vegetable fat/oil raw material containing a free fatty acid to react with a lower alcohol in the presence of a solid acid catalyst, in which the consumption of the lower alcohol is reduced and the free fatty acid and the lower alcohol are selectively esterified to reform the animal/vegetable fat/oil. In this method, as a solid acid catalyst is used a catalyst selected from an SiO2/Al2O3 solid acid catalyst, an SiO2/Al2O3 solid acid catalyst with aluminum being partially introduced into mesoporous silica, an Al2O3/B2O3 solid acid catalyst, and a sulfated zirconia solid acid catalyst, with a molar ratio of the free fatty acid and the lower alcohol of 1 to 6.

Abstract: The present invention provides a method for producing a biofuel that allows an animal/vegetable fat/oil raw material containing a free fatty acid to react with a lower alcohol in the presence of a solid acid catalyst, in which the consumption of the lower alcohol is reduced and the free fatty acid and the lower alcohol are selectively esterified to reform the animal/vegetable fat/oil. In this method, as a solid acid catalyst is used a catalyst selected from an SiO2/Al2O3 solid acid catalyst, an SiO2/Al2O3 solid acid catalyst with aluminum being partially introduced into mesoporous silica, an Al2O3/B2O3 solid acid catalyst, and a sulfated zirconia solid acid catalyst, with a molar ratio of the free fatty acid and the lower alcohol of 1 to 6.