Methane Combustion and CO Oxidation on Ag-Doped LaMn0.8Cu0.2O3 Mixed Oxides Prepared by Pechini and Sol–Gel Methods

Lanthanum in the A-site of LaMn0.8Cu0.2O3?? perovskite was partially substituted by silver. La1–xAgxMn0.8Cu0.2O3 samples (x=0, 0.1, 0.2, 0.3) were prepared by the two Pechini and sol–gel methods and their catalytic activity was evaluated for CH4 combustion and CO oxidation reactions. FT-IR analysis of different samples before calcination confirmed the formation of different complexes between the elements. Calcined samples were characterized using XRD, TPR, BET, SEM and XRF techniques. XRD results revealed that the Pechini method led to perovskite structures with higher purity and that segregation of Ag in samples prepared by the sol–gel method was higher. SEM images and EDS results for samples before and after catalytic tests showed that the Pechini samples had a lower particle size and better distribution of the elements. The catalytic results indicate that the oxidation activity increased with the amount of Ag in the oxide, but the stability of the structure decreased.