Gut I. The oxidation of small molecules on surface of tungsten and molybdenum oxides with supported platinum group metal and cesium

The catalytic systems on the base of oxides WO3 and MoO3 with supported Pt (Pd) are examined in the reactons of Н2, CO and СН4 oxidation. It is shown, that obtained catalytic systems posseses higher catalytic activity in reactions of Н2 and CO oxidation than supported catalysts Pt/Al2O3 (Pd/Al2O3) with the same content of supported metals and close values of specific surface; and essentially exceeds the catalytic activities of the oxides WO3 (MoO3). It is determined, that the increase of specific surface and catalytic activity of samples based on oxides WO3 and MoO3 with supported Pt (Pd) and also Cs+ is caused in changes of the chemical composition of the oxides during their reduction. In particular, the changes occur due to hydrogen spillover, namely, formation of hydrogen or cesium bronzes and in a part with formation of reduced oxides WO2,9 or Mo4O11, which have oxygen vacancies in a surface layer. Kinetic regularities of hydrogen oxidation are examined, the reaction rate equation is proved and itis shown, that experimental data are in a well agreement with the Eley-Rideal mechanism. Kinetic regularities of carbon monoxide oxidation are studied, and the mechanism of CO oxidation is proposed, in accordence with idem the reaction proceeds on a surface of the catalyst in a low-active state, and both the Eley-Rideal and heterogeneous-homogeneous mechanisms can coexist in a high-activity state. It is shown, that WO3 (MoO3) supported with Pt (Pd) demonstrates higher catalytic activity in the methane oxidation at temperatures < 700 K, than Pt/Al2O3 and Pd/Al2O3.