Electron Microscopy Investigations of Nanostructured Ce/Mn Oxides for Catalytic Wet Oxidation

A series of Ce/Mn oxides has been characterized using a variety of complementary transmission electron microscopy techniques to obtain nanometer scale information on the structure, chemical composition, and oxidation states of the different phases present in this extremely complex system. The phases have been identified to be α-Mn2O3, β-MnO2, mixed-valence manganese oxides (Mn3O4 and Mn5O8), and Ce−Mn mixed oxides in different proportions depending on the Ce/Mn atomic ratio. A correlation between the nanostructure of this composite system and its catalytic activity for the wet oxidation of phenol, as a model contaminant, is proposed.