Synthesis of Mo–Fe3O4@SiO2@P4VP core–shell–shell structured magnetic microspheres for alkene epoxidation reactions

Molybdenum complexes immobilized on core–shell–shell structured Fe3O4@SiO2@poly(4-vinylpyridine) microspheres have been successfully fabricated by grafting [3-(methacryloyloxy)propyl]trimethoxysilane on Fe3O4@SiO2 followed by seeded emulsion polymerization of 4-vinylpyridine monomers. The synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field-emission scanning electron microscopy (FESEM), x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectra (FT-IR) and magnetometer. Their catalytic property was investigated by epoxidation of alkenes, using environmentally friendly H2O2 and ethanol as oxidant and solvent, respectively. The results show that Mo–Fe3O4@SiO2@P4VP catalyst possesses high conversion (99.0%) and selectivity (99.0%) in the epoxidation of cis-cyclooctene at 60 °C for 24 h, and the catalyst can be recovered using a magnet and still shows high conversion (95.0%) and selectivity (99.0%) after being recycled three times. -- Highlights: ► Core–shell–shell structured Mo–Fe3O4@SiO2@P4VP microspheres were fabricated. ► The catalyst shows high activity in the epoxidation of alkenes. ► Environmentally friendly H2O2 and ethanol are used as oxidant and solvent. ► The catalyst can be quickly magnetically recovered and maintains high activity.