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

DINAMARCA, R., GARCIA, X., JIMENEZ, R., FIERRO, J.L.G., PECCHI, G.:
Materials Research Bulletin, 81, 134-141 (2016).

DOI: 10.1016/j.materresbull.2016.05.007

Abstract

The influence of lanthanum stoichiometry in Ag-doped (La_1-xAg_xMn_0.9Co_0.1O₃) and A-site deficient (La_1-xMn_0.9Co_0.1O_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, O₂-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, Ag₂O segregated phases and the redox pair Mn⁴⁺/Mn³⁺. A poor catalytic activity for soot combustion was observed with A-site deficient perovskites, despite the increase in the redox pair Mn⁴⁺/Mn³⁺, which is attributed to the cubic crystalline structure.