Thermal stability of Pd or Pt loaded Ce0.68Zr0.32O2 and Ce0.50Zr0.50O2 catalyst materials under oxidising conditions

The sintering behaviour of Pd or Pt loaded ceria-zirconia solid solutions o f nominal composition Ce0.50Zr0.50O2 and Ce0.68Zr0.32O2 was studied under o xidising conditions. Calcination treatments were carried out under controll ed oxidising atmosphere for periods of up to 96 h. Powder X-ray diffraction and BET nitrogen adsorption-desorption derived surface area data are repor ted for the bare materials and for those loaded with low (<1% w/w) amounts of the noble metals, palladium and platinum. Phase demixing was observed as sintering progressed for both of the compositions studied with some differ ences in behaviour observed between the noble metal free and noble metal lo aded catalysts. The results are discussed from a thermodynamic viewpoint, w hich allows to distinguish the behaviour of the two compositions during the demixing process. (C) 2001 Elsevier Science B.V. All rights reserved.