Optimization of biodiesel production via oleic acid esterification over a novel NiMoO4 catalyst supported on functionalized lightweight expanded clay aggregate (LECA)

Abstract

This study evaluates a nickel molybdate catalyst supported on functionalized lightweight expanded clay aggregate NiMoO 4 -f-LECA synthesized via a microwave-assisted route for biodiesel production. Characterization confirmed the successful dispersion of NiMoO4 nanoparticles, yielding a hierarchically porous solid acid catalyst with a surface area of 28.20 m 2 /g, pore volume of 0.121 cm 3 /g, and strong acid sites (NH 3 -TPD peak at 596.5 °C). Response Surface Methodology (RSM) based on a Box-Behnken design optimized the esterification of oleic acid across four variables: temperature (90–110 °C), time (1−3 h ), methanol-to-oil ratio (12:1–20:1), and catalyst dosage (1–5 wt%). The developed quadratic model showed high precision (R2 = 0.9797). Under optimal conditions (100 °C, 3 h, 20:1 M ratio, and 1.05 wt% catalyst), a maximum biodiesel conversion of 90.17% was achieved, closely matching experimental validation. The NiMoO 4 -f-LECA catalyst represents a cost-effective, highly efficient, and sustainable route for scalable biodiesel synthesis.