Kantserova M. The influence of nano-dimensional factor on catalytic properties of complex oxide systems in reaction of deep oxidation of methane.

The method of preparation of supported nano-sized catalysts under non-equilibrium conditions providing high dispersity of manganese oxides (L ~ 3 nm), conservation of nanosized particles, stabilization of Al2O3 low-temperature modifications thus resulting in high activity and thermal stability of alumomanganese catalysts was proposed. Phase nanosized effect in the process of high-temperature treatment of catalysts (900oC, 5 h.) appears evident in reducing temperature of phase conversions Al2O3 while decreasing in their particles size. Low-temperature nano-sized (7-15 нм) catalysts of spinel structure MeFe2O4 (Ме = Mn, Co, Ni), synthesized by thermolysis of multimetallic tree-nucleus carboxylate complexes of transition metals [Fe2IIIMeIIO(CH3COO)6(H2O)3]·2H2O (MeII-Mn, Co, Ni) were developed. The use of a carrier (Al2O3) and surface-active agents improves thermal stability of catalysts. The influence of factor of nano-dimensions on the rate of methane deep oxidation at relatively low temperatures (below 450oC) consists in increasing of specific catalytic activity of cobalt- and nickel- ferrites with decreasing of the size of particles. It was found that the most active cobalt-zirconium catalysts were characterized by the higher dispersity of both a support ZrO2 (12-13 nm) and an active component Co3O4 (~ 3 nm). The most active low-temperature catalyst is characterized by highest amount and mobility (reactivity) of oxygen, as well as by presence of strong acidic sites on its surface.