A high-performance FeVO₄-m-kaolin catalyst for biodiesel production: reaction efficiency and intelligent modeling approaches

A modified kaolin-supported iron vanadate (FeVO 4 -m-kaolin) catalyst was developed through alkaline activation of kaolin followed by microwave-assisted deposition of iron vanadate (FeVO 4 ) nanoparticles. Structural analyses by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) confirmed uniform dispersion of FeVO 4 across partially exfoliated kaolin layers without bulk crystalline phases. Textural properties by nitrogen physisorption using Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods revealed a mesoporous architecture with surface area of 9.30 m 2 /g and average pore diameter of 29.4 nm, while surface acidity by temperature-programmed desorption of ammonia (NH 3 -TPD) showed weak, medium and super-strong acid sites. Catalytic activity in oleic acid esterification reached 93.42% conversion at 3 wt% percent loading, methanol-to-oil ratio of 20 to 1, 120 degrees C and 1 h. Conversion to fatty acid methyl esters (FAMEs) was determined by acid-value titration according to European Standard (EN) 14,104. The catalyst retained 93.42, 93.39, 93.35, 93.33 and 93.32% conversion from Run 1 to Run 5, indicating good stability. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) models optimized by genetic algorithm (GA) predicted yield with coefficient of determination (R2) of 0.998 to 0.999 and root mean square error (RMSE) below 4.