Abstract: A series of oxygen-storage materials CeO₂-ZrO₂-Al₂O₃(CZA) with Mn dopant from 0 to 5%(molar fraction) were prepared by the co-precipitation method and characterized by specific surface area measurements(BET), oxygen storage capacity(OSC), X-ray diffraction(XRD), H₂-temperature-programmed reduction(H₂-TPR), and X-ray photoelectron spectroscopy(XPS). The results show that these successfully-prepared CZA solid solutions have an optimum textural performance with a dopant ratio of 0.5% before and after calcining at 1000 ℃ for 5 h. According to the OSC and the H₂-TPR, the oxygen bulk diffusion was the rate-controlled step of oxygen storage and redox when molar fraction of Mn was less than 2%, however, the material with 0.2% Mn displayed optimum performances such as the lagerest OSC and the lowest reduction temperature. The OSC and the redox properties were mainly depended by Mn species when molar fraction of Mn was more than 2%. XPS results show that Mn is transferred from the bulk to the surface of materials by calcination. Moreover, the H₂-TPR show that the MnO_x species on the surface of the fresh samples are mainly consisted of Mn₂O₃ whereas these on the surface of the aged samples mostly are made up of Mn₃O₄.

Key words: CeO₂-ZrO₂-Al₂O₃, MnO_x, Oxygen storage capacity, Redox property