Preparation and application of a novel carbon-based solid acid with Brønsted-Lewis double acid sites for synthesis of biodiesel

A novel carbon-based solid acid catalyst was prepared with chelates of sodium carboxymethyl cellulose and iron sulfate as a carbon precursor, and with concentrated sulfuric acid as sulfonation agent. The physical and chemical properties of prepared catalyst were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), pyridine-FTIR, scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and energy dispersive spectroscopy (EDS). It was used to catalyze the esterification of oleic acid with methanol to prepare biodiesel, and the influence of different reaction conditions on the conversion of oleic acid was investigated. The results show that the catalyst is a solid acid one with both Lewis and Brønsted acid sites. The conversion of oleic acid reaches 96.8% at the reaction temperature of 70℃, the reaction time of 6 h, the molar ratio of oleic acid to methanol of 1:10, and the catalyst dosages of 7.5% based on oleic acid. In addition, the stability performance of the catalyst tested indicates that the catalyst has a good reusability and hydrophobicity.