Study on preparation of Ca/Al/Fe3O4 magnetic composite solid catalyst and its application in biodiesel transesterification

A magnetic composite solid catalyst was prepared by loading calcium aluminate onto Fe3O4 nanoparticles via a chemical synthesis method. The optimum conditions for the catalyst preparation were investigated. The influences of the molar ratio of Ca to Fe, calcining temperature, calcining time on the catalytic performance were studied. The catalyst with the highest activity was obtained when the molar ratio of Ca to Fe was 5:1; calcining temperature was 600 °C and calcining time was 6 h. The catalyst was characterized by thermogravimetric analyses (TGA), X-ray diffraction (XRD), scanning electronic microscope (SEM), Brunauer–Emmett–Teller method (BET) and vibrating sample magnetometer (VSM). Furthermore, the magnetic composite solid catalyst showed high catalytic activity for transesterification reaction for preparing biodiesel and the biodiesel yield reached 98.71% under the optimum conditions. The activity and recovery rate of this magnetic composite catalyst can be well maintained after 5 cycles of catalysis. This catalyst showed magnetism and can be easily separated magnetically. Both the catalytic activity and the recovery rate of the magnetic composite solid catalyst were much higher than those of pure calcium aluminate catalyst.