Catalytic efficiency and reusability of K2O/M-aluminate (M = Mg, Zn, Cu) nanocatalyst in the esterification of sunflower oil with methanol for biodiesel production

Abstract

The study aimed to investigate the esterification reaction of sunflower oil with methanol using K₂O/M-aluminate nanocatalysts (M = Mg, Zn, Cu) and compare its performance with pure K₂O nanoparticles. A heterogeneous K₂O/M-aluminate nanocatalyst was synthesized through the mechanochemical-impregnation method. The properties of the catalysts were identified using XRD, FESEM, EDX, and the BET methods. The accuracy of each catalyst’s synthesis was verified, followed by analyzing biodiesel success production and conversion measurement using ¹H NMR spectroscopy. Benefiting from the higher surface area (17.82 $\frac{m^2}{g}$), pore volume (0.062 $\frac{\mathrm{mL}}{g}$), and good dispersion of K₂O nanoparticles over the aluminate-based support, the highest conversion (93 %) and yield (94 %) in biodiesel production were achieved using the K₂O/Zn-aluminate catalyst under specific operational conditions. These conditions included a reaction temperature of 70 °C, a reaction time of 3 h, a methanol-to-oil ratio of 1:16, and a catalyst amount of 1 wt%. Furthermore, the catalyst’s potential for reusability was investigated, and the results showed that it could be used at least four times with a little reduction in the yield.