Sodium tungstate immobilised on plasma treated membranes: preparation, characterization and use in flat membrane reactors

The current trend towards a sustainable chemistry has given life to an increasing number of new strategies for catalyst immobilization, enabling an easy recovery, re-use and disposal at low cost of the catalyst. New heterogeneous oxidation catalysts have been obtained by immobilizing sodium tungstate on plasma treated PVDF membranes. The new catalytic membranes were successfully used for the oxidation of secondary amines to nitrones in flat membrane reactors (MRs). Nitrones are versatile and valuable synthetic intermediates for the synthesis of heterocycles and natural products and they are also effective spin trap reagents [1]. Polymeric membranes based on polyvinilidene fluoride (PVDF) polymer with different thicknesses, morphologies and pore dimensions were prepared by nonsolvent induced phase inversion technique. The membranes have been surface modified with NH3 RF glow discharges in order to graft amino groups active sites for immobilizing in a stable way sodium tungstate.