Effect of A-site deficiency in LaMn0.9Co0.1O3 perovskites on their catalytic performance for soot combustion

Abstract The influence of lanthanum stoichiometry in Ag-doped (La 1-x Ag x Mn 0.9 Co 0.1 O 3 ) and A-site deficient (La 1-x Mn 0.9 Co 0.1 O 3-δ ) perovskites with x equal to 10, 20 and 30 at.% has been investigated in catalysts for soot combustion. The catalysts were prepared by the amorphous citrate method and characterized by XRD, nitrogen adsorption, XPS, O 2 -TPD and TPR. The formation of a rhombohedral excess-oxygen perovskite for Ag-doped and a cubic perovskite structure for an A-site deficient series is confirmed. The efficient catalytic performance of the larger Ag-doped perovskite structure is attributed to the rhombohedral crystalline structure, Ag 2 O segregated phases and the redox pair Mn 4+ /Mn 3+ . A poor catalytic activity for soot combustion was observed with A-site deficient perovskites, despite the increase in the redox pair Mn 4+ /Mn 3+ , which is attributed to the cubic crystalline structure.