Novel Brønsted‐Lewis Acid Heterogeneous Catalyst: Functionalized Imidazolium Ferric Salts@SBA‐15 for Efficient Production of Biodiesel

Abstract Brønsted‐Lewis acid heterogeneous catalyst functionalized imidazolium ferric salts@SBA‐15 ([DSIM][FeCl 4 ]/SBA‐15) with large specific surface and mesoporous structure was designed and prepared to catalyze the esterification of oleic acid with methanol for yielding biodiesel (fatty acid methyl ester). The as‐prepared catalyst showed good catalytic performance with 98.2% conversion of oleic acid under the optimal reaction conditions: the molar ratio of methanol and oleic acid was 10:1 and the amount of catalyst was 5% of oleic acid mass, 4 h and 70 °C. The samples were characterized by X‐ray diffraction, FT‐IR, N 2 adsorption‐desorption, Pyridine‐adsorbed FT‐IR, Thermogravimetric analysis, Energy dispersive X‐ray spectroscopy, scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). The results demonstrated that imidazolium ferric salt was successfully loaded onto the surface of SBA‐15 and the catalyst retained the mesoporous structure of the support. The catalyst [DSIM][FeCl 4 ]/SBA‐15 still performed over 85.5% of conversion after 5 reaction cycles, which indicated its good stability and reusability.