The effect of low Ag substitution in LaFeO3 perovskite on the thermal stability and catalytic oxidation of toluene was studied. Perovskites of the type La1-xAgxFeO3 (xAg=0.0, 0.05, 0.10) were prepared by the amorphous citrate method; characterized by nitrogen adsorption, XRD, FTIR, SEM-EDAX, TPR and O2-TPD techniques; and tested for the catalytic combustion of toluene in a flow reactor under excess oxygen. In comparison with the pure perovskite LaFeO3, the partially substituted La1-xAgxFeO3 present a perovskite structure with well-defined crystalline phases and greater reduction ability (attributable to the redox pair Fe+3/Fe+4). Noticeable changes in the α and β-oxygen contents upon silver substitution were detected. Larger content of α-oxygen in the pure LaFeO3 perovskite is associated with greater catalytic activity. Two important effects upon Ag substitution in a pure LaFeO3 perovskites were observed: i) a greater reduction ability, ii) higher occurrence of oxygen vacancies due to β-oxygen desorption, which were not active in the studied reaction.
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