Synthesis and performance evaluation of dextrose-derived sulfonated carbon solid acid catalyst for efficient biodiesel production

A dextrose-derived activated sulfonated carbon solid acid catalyst (DAC-SO₃H) was successfully synthesized through ZnCl₂-assisted activation followed by sulfuric acid sulfonation and evaluated for biodiesel production via esterification of oleic acid. The influence of the dextrose-to-ZnCl₂ ratio on catalytic performance was investigated, with DAC-1:1-SO₃H exhibiting the highest biodiesel yield of 98.3%. Structural and surface characterization confirmed the formation of a highly porous carbonaceous material possessing abundant acidic functionalities and a high surface area of 1806.76 m² g⁻¹. Optimization studies identified 8 wt% catalyst loading, 100 °C reaction temperature, 60 min reaction time, and a methanol-to-oleic acid molar ratio of 20:1 as the optimum conditions. NMR analysis confirmed 99.5% conversion of oleic acid to methyl oleate. The catalyst maintained excellent structural integrity after five reuse cycles, yielding 89.5% biodiesel. The produced biodiesel satisfied ASTM fuel specifications, demonstrating the potential of DAC-SO₃H as an efficient catalyst for biodiesel production. This study presents the synthesis of a dextrose-derived ZnCl₂-activated sulfonated carbon solid acid catalyst with a high surface area (1806.76 m² g⁻¹) for biodiesel production via oleic acid esterification, demonstrating high catalytic activity, high methyl oleate conversion, and excellent reusability.