Mechanochemical preparation of ceria-zirconia catalysts for the total oxidation of propane and naphthalene Volatile Organic Compounds

A range of ceria-zirconia mixed metal oxide catalysts were synthesised by mechanochemical milling from nitrate precursors and tested for propane and naphthalene total oxidation. The mixed CeZrOx metal oxide catalysts were more active compared to pure CeO2 and ZrO2, with the Ce0.90Zr0.1Ox catalyst the most active for both propane and naphthalene total oxidation. Catalysts were characterised by XRD, TGA, Raman spectroscopy, BET surface area, XPS, TEM and SEM-EDX techniques. Formation of CeZrOx solid solutions were observed for Zr content ranging from 5 to 25%, and phase separated materials were observed for higher Zr content of 50%. The incorporation of Zr into the CeO2 lattice increased the surface area compared to pure CeO2 and ZrO2, with evidence of a surface enrichment of Zr when concentrations were compared to the bulk. Incorporation of Zr was found to increase the surface concentration of oxygen defects in the CeZrOx mixed metal oxides, the concentration of these defect on the catalysts follows a similar trend to the propane and naphthalene total oxidation activity: The increased presence of oxygen defects and reducibility are factors responsible for the enhanced total oxidation activity of the mixed metal oxide catalysts and the mechanochemical method is an effective preparation route for these active catalysts.