A magnetically recyclable heterogeneous catalyst: Cobalt nano-oxide supported on hydroxyapatite-encapsulated γ-Fe2O3 nanocrystallites for highly efficient olefin oxidation with H2O2

High catalytic activity of cobalt nano-oxide supported on hydroxyapatite-encapsulated magnetic γ-Fe2O3 nanocrystallites had been prepared. HR-TEM characterization demonstrated the formation of γ-Fe2O3 nanocrystallites within the HAP matrix with a mean diameter of 1–3 nm. The mixed Co3O4 and CoFe2O4 oxides were existed on the surface of CoHAP-γ-Fe2O3. The CoHAP-γ-Fe2O3 exhibited good catalytic activity for the oxidation of various alkenes based on a cooperation effect between these two oxides. The magnetic properties of the CoHAP-γ-Fe2O3 provided a convenient route for separation of the catalyst from the reaction mixture by application of an external permanent magnet. The spent catalyst could be recycled without appreciable loss of catalytic activity.