Structure and oxygen storage capacity of Pr/Nd doped CeO2-ZrO2 mixed oxides

Binary Ce-Zr (CZ), trinary Ce-Zr-Pr (CZP), Ce-Zr-Nd (CZN) mixed oxides were prepared by coprecipitation. The structural and textural properties were characterized by the X-ray diffraction (XRD) analysis, Brunauer-Emmett-Teller (BET) method, Raman and X-ray absorption near-edge spectra (XANES) techniques, while the oxygen storage capacity OSC was evaluated under both dynamic and static conditions at 500 degrees C. The doping of Pr or Nd cations causes the lattice deformation of the tetragonal Zr-rich mixed oxides to form a pseudocubic structure and prevents the phase demixing after calcination in flowing steam/air at 1050 degrees C for 5 h. After the hydrothermal ageing treatment, the doped samples show higher BET surface areas and better oxygen mobility. Pr exists mainly in the form of trivalent cations in the aged CZP and functions primarily as the doping element with large ionic radius instead of redox couple Pr(3+)/Pr(4+), which may introduce more Ce(3+) species and hereby more lattice defects. Among the aged samples, CZP shows the best oxygen storage capacity and the fastest oxygen release rate. (c) 2007 Elsevier Masson SAS. All rights reserved.