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 gamma-Fe2O3 nanocrystallites had been prepared. HR-TEM characterization demonstrated the formation of gamma-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-gamma-Fe2O3. The CoHAP-gamma-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-gamma-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. (C) 2008 Elsevier B.V. All rights reserved.