Investigation of Jatropha Oil Transesterification into Methyl Esters under Supercritical Methanol Environment using Advanced Heterogeneous Catalysts

The rationale for this study lies in the investigation of the transesterification of crude Jatropha curcas oil into biodiesel using advanced heterogeneous catalysts under supercritical methanol conditions. The oxides of strontium, lanthanum, and zinc (SrO, La₂O₃, and ZnO) were synthesized with varying loadings (2 wt %, 6 wt %, and 10 wt %) on γ-Al₂O₃ using the wet impregnation method followed by calcination at 900 °C. To gain a comprehensive understanding of the prepared catalysts, multiple analytical techniques were employed, including scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The performance of the catalysts was assessed through the measurement of biodiesel yield, where the SrO/γ-Al₂O₃, ZnO/γ-Al₂O₃, and La₂O₃/γ-Al₂O₃ systems produced yields of 97.54 %, 97.49 %, and 97.36 %, respectively, under identical reaction conditions of a 1 : 40 oil to methanol molar ratio, 10 wt % catalyst loading amount, 300 °C reaction temperature, 90 bar reaction pressure, and a reaction time of 3 min. Despite a minimal decrease of 0.05 %, zinc oxide catalysts remain highly attractive due to their favorable price position compared to strontium. Additionally, the catalyst can be reused up to 12 times with minimal loss in biodiesel yield (~2 %).