Design and performance of molybdenum-modified KIT-6 heterogeneous acid catalyst for biodiesel production via Taguchi-based optimization

This study focuses on the development of a highly stable and effective heterogeneous acid catalyst, comprising molybdenum oxide supported on mesoporous silica KIT-6, for biodiesel production. A series of catalysts were synthesized via sol–gel and wet impregnation methods and evaluated in the transesterification reaction of waste cooking oil (WCO). The developed catalyst was characterized using surface acidity measurement, X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), N 2 Physisorption, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Transmission Electron Microscopy (TEM), and Thermogravimetric Analysis (TGA). To optimize the biodiesel ester content, an experimental design using the Taguchi Method evaluated the effect of reaction temperature, MeOH:oil molar ratio, catalyst concentration, and reaction time. The regression model showed R 2 = 0.93 and achieved a maximum experimental ester content of 92.7 % (relative error < 5 %) under optimal conditions: 160 °C, 13:1 MeOH:oil ratio, 10 wt% catalyst, and 2.4 h. The 6-Mo/KIT-6 catalyst exhibited stable performance over four transesterification cycles, maintaining ester content above 80 %. This indicates its strong potential as a heterogeneous acid catalyst for sustainable biofuel production.