Catalytic behavior and electrical conductivity of LaNiO 3 in ethanol oxidation

Abstract

The oxidation of ethyl alcohol vapor on perovskite type LaNiO 3 oxide was conducted in flowing air. Characterization of catalysts was carried out by TPD techniques and the conductivity change of the oxide during oxidation was measured to correlate catalytic properties and electrical conductivity of the material. It was demonstrated that the oxidation reaction is accompanied by transfer of charge or a loss of oxygen from the surface as well as a change in the conductivity of the oxide. The oxidation rate was found to follow the power law kinetic, r = k[O 2] 0[ethanol] 1, and the resistance R followed as R = R 0(1 + α [ethanol] β ), where α and β are the constants depending on temperature. The degree of the conductance change depended on the concentration of ethanol vapor, the oxidation circumstances, and the reaction temperature. Increase in temperature led to a change in the states of surface oxygen, O − or O 2−, and, hence, the interactions between them. The ethanol vapor showed higher conductance change in the temperature range between 250 and 350°C. Together with the study of redox mechanism, the ralations of oxidation rate and conductance as a function of reactant concentration are also discussed.