Preparation of polyoxometalate-stabilized colloidal solutions of palladiummetal and catalysts supported on them

Sols containing Pd(0) clusters with polyoxo anions are prepared by the redu ction of colloidal solutions of polyhydroxo complexes of Pd(II) in the pres ence of Mo(VI), W(VI), V(V), and Nb(V) polyoxo anions. The cluster sizes va ried within the limits of 1-10 nm depending on the nature of the polyoxo an ion. The stability of sols toward coagulation depends on the ratio between the palladium and polyoxo anion amounts in solution and on the composition of the solvent. Supported Pd catalysts are obtained by the adsorption of pa rticles from sols; Pd can exist in these catalysts as individual particles or associates or form filamentary structures.