Preparation and kinetic study of magnetic Ca/Fe3O4@SiO2 nanocatalysts for biodiesel production

Abstract

The novel magnetic Ca/Fe3O4@SiO2 nanocatalysts were prepared via combination of sol-gel and incipient wetness impregnation methods for biodiesel production. This research investigates the effect of different Ca/(Fe3O4@SiO2) weight percentage on the catalytic performance. The best operational conditions were the CH3OH/oil = 15/1 at 65 °C with mechanical stirring for 5 h. Furthermore, the optimal nano catalyst showed high catalytic activity for biodiesel production and the biodiesel yield reached 97% under the optimal conditions. From the TPD results, the high basicity of catalysts enabled high yield of biodiesel was obtained. The catalyst could be recovered simply by using an external magnetic field and reused several times without appreciable loss of its catalytic activity. From the kinetic and thermodynamic studes, Ea = 47.03 kJ, A = 1.9 × 10 5 min−1, ΔH = 112.56 kJ mol−1 and ΔS = 298.63 J mol−1 K−1 were obtained. Characterization of catalysts was carried out by using scanning electron microscopy (SEM), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), temperature programmed desorption (TPD), Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential thermogravimetric analysis (DTA), Fourier transform-infrared spectroscopy (FT-IR) and N2 adsorption–desorption measurement methods.