Magnetic solid acid Fe3O4@SiO2-SO3H for cellulose hydrolysis

The micro/nano-Fe3O4 prepared by solvothermal method was embedded in silica to afford a core-shell structure of Fe3O4@SiO2. The magnetic solid acid, Fe3O4@SiO2-SO3H, was obtained by the sulfonation of the core-shell composite, and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDS). Its acid content and application performance for cellulose hydrolysis were further investigated. The saturation magnetization and maximum acid content of the solid acid are found to be 9.81 emu center dot g(-1) and 3.36 mmol center dot g(-1), respectively. The solid acid catalyzed cellulose hydrolysis at 150 celcius with the solid acid dose of 2.5 g per gram cellulose produces glucose in the yield of 59.91% in 7 h. The solid acid is successfully recycled from the hydrolysate with a magnet, and the magnetization and catalysis performance for cellulose hydrolysis show no significant changes in 5 cycles.