An investigation of influence of copper on the redox properties and catalytic performance of LaMnO3+λ perovskite- type catalyst

Modified perovskite-type oxides were synthesized through gel combustion method. The synthesized perovskite materials had the nominal compositions of LaMnO3 and LaMnCu0.1O3. The catalytic activity of the perovskite samples (for low-temperature CO and C3H8 oxidation) was measured using a quartz reactor with an inlet gas mixture containing CO, propane, O2 as synthetic automotive exhaust gas and Ar as an inert gas. The prepared perovskite samples were characterized by nitrogen adsorption (BET), XRD and TPR analyses. TPR and XRD results may indicate that copper was in the form of solid solution in perovskite structure and the excess manganese oxide in LaMnCu0.1O3+δ is in the form of amorphous small particles. The perovskite catalysts showed high activity for the catalytic CO and propane oxidation reaction. LaMnCu0.1O3 achieved the same CO and propane conversion at lower temperatures than LaMnO3. The light off temperature for CO and propane on LaMnCu0.1O3 were lower by 70 and 20oC, as compared to that of LaMnO3 perovskite. Hence, for the environmental application of the automotive emission control, these catalysts can completely eliminate the poisonous CO and unburned hydrocarbons.