THERMOCATALYTIC SENSORS WITH PD-PT-AL2O3 CATALYST

The pecularities of the temperature dependence of the output signals o f thermocatalytic sensors (TCS), having metal-oxide catalysts of vario us composition (Pd-Al2O3, Pt-Al2O3, Pd-Pt-Al2O3), annealed in air and in methane-air mixture, in the process of methane detection are invest igated. The obtained results were analysed with regard to the data of catalyst phase composition change in situ and of the Pd and Pt valency state. The conclusion was made that one of the possible reasons for t he higher output signal stability in thermocatalytic sensors with the Pd-Pt-Al2O3 catalyst is the stability increase of Pt in the presence o f Pd+ and Pd2+ palladium ion forms, which are most active in the react ion of deep methane oxidation.