High-performance magnetite nanoparticles catalyst for biodiesel production: Immobilization of 12-tungstophosphoric acid on SBA-15 works effectively

Abstract

Magnetic mesoporous solid acid catalysts, designed as Fe3O4@SBA-15@HPW and Fe3O4@SBA-15-NH2-HPW, were prepared for the production of biodiesel by the transesterification of palm oil with methanol. The magnetic mesoporous carrier was modified by two different methods: post-gifting method and impregnation method. The structure of the catalysts was characterized by SEM, TEM, XRD, FT-IR, VSM, Pyridine-FT-IR, N2 adsorption-desorption and TGA. The results indicated that they all had ordered mesoporous and excellent paramagnetic. Both Fe3O4@SBA-15@HPW and Fe3O4@SBA-15-NH2-HPW had high content of Brønsted acid sites due to the loading of 12-tungstophosphoric acid, which made the two catalysts very active. Particularly, Fe3O4@SBA-15-NH2-HPW was very efficient in the transesterification of palm oil with methanol and gave a more than 91% biodiesel yield when the reaction was carried out at 150 °C with a 4 wt% catalyst amount at 20:1 methanol/oil molar ratio for 5 h Fe3O4@SBA-15-NH2-HPW prepared by the grafting method exhibited higher reusability, and the yield of biodiesel was more than 80% after 6 times cycles, which made the catalyst have an excellent industrial application prospect.