Preparation of a magnetic solid acid Fe3O4@PS-SO3H and its use in hydrolysis of cellulose

BACKGROUND: In order to improve the catalytic performance and stability of magnetic solid acid for cellulose hydrolysis in the aqueous phase, this study first modified the surface of magnetite (Fe3O4) nanoparticles (NPs) with oleic acid. Then, in an oil-in-water (O/W) emulsion system, polystyrene (PS) was coated on the Fe3O4 NPs through emulsion polymerization. Finally, magnetic solid acid Fe3O4@PS-SO3H was prepared by sulfonation. RESULTS: The obtained Fe3O4@PS-SO3H was characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, infrared, X-ray diffraction, X-ray photoelectron spectroscopy and thermogravimetric analysis, and its acid densityand magnetic properties determined. Applied to cellulose hydrolysis, it exhibited 35.28 emu<middle dot>g(-1) saturation magnetization and 3.56 mmol<middle dot>g(-1) maximum acid density. At 140 degrees C and 1:1 acid to substrate ratio, cellulose hydrolysis with Fe3O4@PS-SO3H gave a glucose yield of <= 64.14% in 10 h. The solid acid was conveniently recycled with a magnet and reused for further cellulose hydrolysis. It maintained good catalytic activities after five cycles. CONCLUSION: The magnetic solid acid with a polystyrene backbone prepared by emulsion polymerization exhibits efficient and stable catalytic performance, in line with the trend of green development in 'bio-refining', and lays the foundation for the development of composite solid acids. (c) 2024 Society of Chemical Industry (SCI).