Magnetic Solid Base Catalysts for the Production of Biodiesel

Magnetic solid base catalysts were prepared by loading Na₂SiO₃ on Fe₃O₄ nano-particles with Na₂O·3SiO₂ and NaOH as precipitator. The catalysts were used to catalyze the transesterification reactions for the production of fatty acid methyl esters (FAME, namely biodiesel) from cottonseed oil. The optimum conditions of the catalysts' preparation and transesterification reactions were investigated by orthogonal experiments. The catalyst with the highest catalytic activity was obtained when Si/Fe molar ratio of 2.5, aging time of 2 h, calcination temperature of 350 °C, calcination time of 2.5 h. Magnetic of the catalyst was characterized with Vibrating Sample Magnetometer (VSM) and transmission electron microscopy photograph (TEM), and the results showed the catalyst Na₂SiO₃/Fe₃O₄ had good specific saturation magnetization and paramagnetism, and its water resistance was better than the traditional homogeneous base catalysts; under the transesterification conditions of methanol/oil molar ratio of 7:1, catalyst dosage of 5%, reaction temperature of 60 °C, reaction time of 100 min and stirring speed of 400 rpm, yield of biodiesel was 99.6%. The lifetime and recovery rate of the magnetic solid base catalyst were much better than those of Na₂SiO₃.