Effect of the amount of Pt loading on the oxygen storage capacity of ceria-zirconia solid solution

Abstract

As an important oxygen storage material, ceria-zirconia solid solution is widely used in automotive three-way catalysts. For the Ce-Zr solid solution being usually used with a noble metal, the evaluation of oxygen storage capacity (OSC) should be conducted with the Ce-Zr solid solution loaded with a noble metal. The measured OSC of noble-metal-loaded Ce-Zr solid solution consists of two parts: the stored oxygen within the solid solution itself and the adsorbed oxygen on the loaded noble metal particles. Therefore, it is very necessary to clarify the influence of metal loading on the measured OSC in order to ascertain the exact OSC of the solid solution itself. In this research, the authors attempted to clarify the above issues by characterizing the OSC performance of Ce-Zr solid solutions with platinum (Pt) loading from 0.0001-10 mass%. We found that increasing the amount of Pt loading increases the oxygen storage and release rates and that increasing the temperature also increases the oxygen storage rate, although the oxygen release rate is not affected by increasing the temperature. The apparent OSC reached saturation over a certain amount of Pt loading and temperature. The saturated OSC increased with increasing temperature.