Influence of partial Mn-substitution on surface oxygen species of LaCoO3 catalysts

A series of LaCo1−xMnxO3 (x = 0.05, 0.1, 0.3, 0.5, 0.7) perovskite-type catalysts were prepared by citric acid sol–gel method to study the influence of partial Mn-substitution on the catalytic performance and surface oxygen species of LaCoO3 perovskite-type catalysts. Their catalytic performances for particulate matters (PM) oxidation were investigated by a technique of temperature-programmed oxidation reaction (TPO), indicating that the catalytic performance of LaCo0.95Mn0.05O3 is better. The catalysts were characterized by XRD, BET, IR, H2-TPR, O2-TPD and XPS. The results show that LaCo1−xMnxO3 catalysts have perovskite-type structures after partially substituted by Mn. There are three kinds of oxygen species, lattice oxygen ion O2−, peroxide ion O− and superoxide ion O2−, are present on the surfaces of catalysts. The content of surface oxygen species varies with Mn-substitution amount. Superoxide ion O2− and surface oxygen vacancy play an important role in the reaction of PM oxidation.

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► A small amount of Mn-substitution promotes PM oxidation.
► There are three kinds of surface oxygen species on the surface of the catalysts.
► Mn-substitution amounts affect the contents of lattice oxygen ion and superoxide ion.
► Superoxide ion and oxygen vacancy play role in the reaction of PM oxidation.