Magnetically Recoverable Heterogeneous Catalyst: Tungstate Intercalated Mg–Al-Layered Double Hydroxides-Encapsulated Fe3O4 Nanoparticles for Highly Efficient Selective Oxidation of Sulfides with H2O2

High catalytic activity of tungstate intercalated in hydrotalcite-encapsulated magnetic Fe 3 O 4 nanoparticles have been prepared. High resolution transmission electron microscopy characterization demonstrated the formation of Fe 3 O 4 nanoparticles within LDH matrix with a mean diameter of 1–3 nm. The catalyst of WO 4 2− /LDH@Fe 3 O 4 exhibited excellent catalytic activity for the oxidation of various sulfides. The magnetic properties of the WO 4 2− /LDH@Fe 3 O 4 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. Graphical Abstract .