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

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.