Ordered mesoporous carbon supported ferric sulfate: A novel catalyst for the esterification of free fatty acids in waste cooking oil

Ordered mesoporous carbon (OMC) supported ferric sulfate (FS) catalysts were prepared by impregnation, and their catalytic activity for the esterification of the free fatty acids (FFAs) in waste cooking oil (WCO) with methanol was evaluated. The FS/OMC catalysts were characterized by N2 adsorption–desorption, powder X-ray diffraction and transmission electron microscopy. The results indicated that catalysts retained the ordered mesoporous structure, and the FS was well dispersed on the surface of the OMC. The FT-IR spectrum of pyridine adsorbed on the FS/OMC catalysts showed the presence of strong Lewis acid sites on the surface of the catalysts. The FS/OMC catalysts exhibited excellent catalytic performances for FFA esterification. In addition, the process variables that influence the esterification of FFAs, such as the FS loading, the amount of catalyst, the molar ratio of methanol to FFAs, the reaction temperature and the reaction time, were investigated and optimized. The FS/OMC catalysts are reusable and maintained their original catalytic activities after six uses.