Biodiesel production from soybean and Jatropha oils by magnetic CaFe2O4–Ca2Fe2O5-based catalyst

Heterogeneous CaFe2O4–Ca2Fe2O5-based catalyst with weak magnetism was prepared by co-precipitation and calcination. It was characterized by various techniques including X-ray diffraction, X-ray photoelectron spectroscopy and temperature programmed desorption method. Its active components were identified as mainly Ca–Fe composite oxides such as CaFe2O4 for transesterification. The magnetism was further strengthened by reducing its component of Fe2O3 to Fe3O4–Fe under H2 atmosphere for better magnetic separation. Both catalysts were used for the catalytic transesterification of soybean and Jatropha oils to biodiesel. The highest biodiesel yields for soybean oil of 85.4% and 83.5% were obtained over the weak and strong magnetic catalysts, respectively under the optimized conditions (373 K, 30 min, 15/1 methanol/oil molar ratio and 4 wt% catalyst). The catalysts could be recycled three times. Biodiesel production from pretreated Jatropha oil was tested with the magnetic CaFe2O4–Ca2Fe2O5–Fe3O4–Fe catalyst, and 78.2% biodiesel yield was obtained. The magnetic CaFe2O4–Ca2Fe2O5-based catalyst shows a potential application for the green production of biodiesel.