Synthesis of a Fe3O4–CuO@meso-SiO2 nanostructure as a magnetically recyclable and efficient catalyst for styrene epoxidation

Abstract

A novel hybrid Fe₃O₄–CuO@meso-SiO₂ catalyst was successfully fabricated by a multi-step assembly method. CuO nanoparticles were first deposited on the surface of Fe₃O₄ microspheres to form the Fe₃O₄–CuO hybrid microspheres through a solvothermal reaction. A mesoporous silica (meso-SiO₂) shell, with perpendicularly aligned pore channels, was then coated on the hybrid microspheres using sol–gel technology. The Fe₃O₄ microspheres not only offered fast and effective recycling properties for the catalyst but also acted as electron donors to CuO, leading to a higher electron density on the CuO surface and a subsequently enhanced catalytic performance. The mesoporous silica shell provided strong protection against the aggregation and leaking of the active CuO nanoparticles and also offered appropriate channels for an efficient mass transfer of the catalytic reaction. The Fe₃O₄–CuO@meso-SiO₂ catalyst exhibited excellent activity, convenient magnetic separability and good stability in the catalytic epoxidation of styrene.