Screening and scale-up of cerium oxide-based binary/ternary systems as oxidation catalysts

Abstract

In the present work, seven samples of cerium oxide-based binary and ternary nanoparticles were prepared by a micro emulsion technique to be used as catalysts for carbon and soot oxidations. Pure CeO₂, binary CeO₂–Fe₂O₃ (with different oxide contents) and Pt–CeO₂–FeO₃ were targeted. Preliminary characterizations by EDX, XRD and N₂ sorption confirmed the formation of nanosized crystallites. The oxidation experiments performed by TGA allowed screening the catalysts. Three of them were then selected: CeO₂ as a reference, Pt₁₂Ce₈₈ and Pt₆Ce₉₀Fe₄. TEM confirmed the nanometric size of the particles and showed aggregation. XPS suggested Ce³⁺, Ce⁴⁺ and active oxygen (O²⁻ and O⁻) as surface species, which are important in the oxidation of carbonaceous compounds. Finally, the Pt-doped samples were scaled up by coating onto the surface of unplugged mini silicon carbide monoliths and tested for oxidation of hydrocarbons and carbon monoxide. Coating was performed by dip-coating. Attractive performance was found. Our main results are reported and discussed herein.