Solid superacid catalyzed fatty acid methyl esters production from acid oil

A solid superacid catalyst was evaluated for the production of fatty acid methyl esters (FAMEs) from acid oil containing about 60 wt.% free fatty acids. It was demonstrated that SO₄^{2 -}/ZrO₂-TiO₂/La³⁺ was an effective catalyst for simultaneous transesterification and esterification. The optimization of reaction parameters was performed, showing that maximum yield of above 90% could be obtained under the conditions that molar ratio of alcohol/oil was 15:1, catalyst amount was 5 wt.%, temperature was 200 °C and duration was 2 h. The catalyst was finally recycled and utilized for five times repeatedly with little loss in activity. The final products purified by molecular distillation were detected by GC-MS. The content of FAMEs reached 96.24%.