Cobalt and manganese oxide catalytic systems on valve metals in ecotechnologies

Abstract

The paper discusses the preparation of cobalt and manganese oxide catalytic systems on valve metals (aluminum and titanium alloys) for eco-technologies. Oxide catalysts with d-metals based on aluminum are widely used for reduce the toxic gases emission from internal combustion engines. Catalysts based on Titania doped with transition metal oxides are also widely used in the heterogeneous and especially photo-catalysis. The higher catalytic properties in this case are demonstrated by the nano-structured oxide systems with developed surface both on aluminum and titanium alloys. From the point of view of the application convenience, better technological forms of a catalyst are the thin-film oxide coatings, formed directly on the metal substrate by the method of plasma-electrolytic oxidizing. It is considered the features of the conversion coatings formation on aluminum and titanium alloys by plasma electrolytic oxidation in alkaline electrolytes. The effect both the concentration and ratio of the electrolyte components and processing conditions on the composition and the morphology of the surface layers is studied. The difference in the plasma oxidation parameters of aluminum and titanium alloys is attributed with the various specific electric resistance of matrix metal as well as the alloying elements oxides. The oxides’ composition influence on the surface relief and their properties is investigated. The factors influenced on the catalytic properties of single and mixed oxide systems are established and the prospects for their use in technology of neutralization of toxic substances are discussed.