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The effects of transition metal (Cu, Co, Ni) oxides and platinum group metals (Pt, Pd, Rh) in composites based on Y(Sc) stabilized zirconia on their catalytic properties (activity, selectivity, sulfur resis tance) and service life characteristics (thermal stability, performance stability) in methane oxidation reactions have been investigated. The high activity of the composites (75-99% methane conversion at 600-800°C) correlates with the amount and mobility of surface oxygen in these materials. The promoting effect of the platinum group metals depends on the composition of the reaction medium (on whether it corresponds to the partial or total methane oxidation and on whether it contains sulfur dioxide).

The effect of the composition of composites based on Y-and Sc-stabilized zirconium dioxide doped with CeO 2 and transition metal (Cu, Co, Ni) oxides on catalytic properties in the oxidative conversion of methane was studied. The activity of the composites correlated with the quantity and mobility of oxygen in them.Key words: oxidation of methane, prototypes of anodes, zirconium dioxide, yttrium and scandium oxides, transition metal oxides, mobility of oxygen.Anodes for the direct oxidation of hydrocarbon fuels is a new direction for the use of the concepts of oxidative heterogeneous catalysis in solid-oxide fuel cells (SOFC). The necessity of three-phase boundaries at the anode -gas phase (fuel), electron-and ion-conducting phases -is the basic difference which causes an additional level of complexity in the investigation of the process in comparison with heterogeneous-catalytic oxidation and the basic requirements for the material of the anode [1]. Composites based on solid oxygen-driven electrolytes -yttrium-stabilized zirconium dioxide (YSZ), modified with transition metals, are active electrode-catalysts in the process of the direct electrochemical conversion of hydrocarbon fuels [2][3][4][5]. The catalytic properties of anode materials in the oxidative conversion of methane are one of the basic factors influencing the effectiveness of SOFC [6].The components of anode materials currently should provide a mixed ion-electron conductivity and high catalytic activity. The most commonly used electrolyte materials have compositions of (8-12)% Y 2 O 3 + ZrO 2 and (8-12)% Sc 2 O 3 + ZrO 2 , the respective average conductivities of which are 1.04·10 -2 and 5.96·10 -2 W -1 ·cm -1 in the temperature range 600-800°C [7-10]. Currently the best from the point of view of ionic conductivity is an electrolyte based on zirconium dioxide, stabilized with scandium oxide and doped with cerium oxide [11]. In addition, doping with CeO 2 secures a high storage capacity for oxygen [12]. Oxides of the transition metals Ni, Co, and Cu are active catalysts for the oxidation of hydrocarbons, possessing adequate electron conductivity.In the current paper results are presented on the study of a number of composites based on zirconium dioxide stabilized with yttrium (YSZ) and scandium (ScSZ)*, doped with CeO 2 and transition metal (Cu, Co, Ni) oxides in heterogeneous catalytic oxidation of methane in the temperature range 550-800°C which is characteristic for medium-temperature SOFC.The catalytic activity of the samples was characterized by conversion of CH 4 into CO and CO 2 which was determined in a quartz flow reactor at atmospheric pressure and a volume rate of the gas mixture of 6000 h -1 . Reaction mixture with 0040-5760/06/4203-0197