Biodiesel production from soybean oils by a novel nano-magnetic solid base catalyst (K/ZrO2/γ-Fe2O3)

Biodiesel is emerging as a green alternative source to fossil fuels due to its clean and renewable advantages. In this study, a nano-solid base catalyst (K/ZrO2/g-Fe2O3) with weak magnetism was successfully synthesized and investigated for transesterification of soybean oil to produce biodiesel. The obtained catalyst was fully characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), thermogravimetry/differential scanning calorimetry device (TG/DSC), and scanning electron microscopy-energy dispersive X-ray (SEMEDX) analysis. Results showed that the nano-magnetic catalyst had granular nano-structures with particle sizes of 15-25 nm. The optimum conditions for transesterification were shown to be as follows: catalyst added amount of 5 wt%; methanol/oil molar ratio of 10 : 1; reaction time of 3.0 h, and reaction temperature of 65 degrees C, and the yield of biodiesel could reach above 93.6 wt%. The reusability of the magnetic catalyst demonstrated that the magnetic catalyst was ferromagnetic and still maintained high catalytic activity after six times' reuse. The formed core-shell was hard to separate even after stirring in liquid phase reactions, which was favorable for use in biodiesel production. The developed nanomagnetic catalyst shows a potential application for biodiesel production in a green manner.