Kinetics and mechanism of Co Oxidation on Ln2NiO4 oxides (Ln ≡ La, Pr or Nd)

Abstract

The oxidation of CO was studied in a static reactor at an initial total pressure of 50 Torr in the temperature range 300–460 °C on Ln2NiO4 oxides (Ln ≡ La, Pr or Nd). The rate of the reaction was found to be first order with respect to the partial pressure of CO and fractional order with respect to the partial pressure of oxygen. The product CO2 was found to inhibit the reaction. Equilibrium adsorption studies of the reactants and product indicated the adsorption properties of the oxide and the participation of lattice oxide ions. In situ electrical conductivity changes of the catalysts in various ambient atmospheres established the charge transfer processes occurring on the surface. A redox mechanism involving the formation of carbonate complex species as intermediates is proposed for the oxidation of CO over these oxides.