▎ 摘　　要

The epoxidation of alkenes to the corresponding epoxides plays a vital role in fine chemical engineering. Magnetic nanocomposite catalyst RGO/Fe3O4@C-N-Co3O4 (RGO: reduced graphene oxide) involving Co3O4 nanoparticles immobilized on magnetic N-doped graphene was prepared by a hydrothermal method. N-dopants in the RGO/Fe3O4@C-N-Co3O4 can strengthen the interaction between Co3O4 nanoparticles and the support. RGO/Fe3O4@C-N-Co3O4 revealed higher catalytic reactivity (i.e. 93.2% conversion of styrene and 88.4% selectivity to styrene oxide) as compared to bulk Co3O4, and Co3O4 supported on N-free RGO/Fe3O4@C due to site-isolation, good dispersion of Co3O4 nanoparticles and efficiently synergistic effect between Co3O4 and the magnetic support. In addition, the catalyst displayed good recoverability by simple magnetic separation with negligible loss in activity and selectivity within several successive runs due to superparamagnetism. (C) 2017 Elsevier B.V. All rights reserved.