ナノメータコンポジット材料 白金／セリア‐ジルコニア固溶体微粒子の酸素貯蔵能に及ぼす白金担持量の影響

Abstract

Ceria-zirconia (Ce-Zr) solid solution is widely used as an oxygen storage material, which is a key component in the automotive three-way catalysts. The Ce-Zr solid solution is usually used with noble metals supported on their surface. Thus the evaluation of oxygen storage capacity (OSC) should be conducted on 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; one is the stored oxygen within the solid solution itself, and the other is the adsorbed oxygen on the surface of the supported noble metal particles. Therefore, it is necessary to clarify the influence of the noble metal on the measured OSC, and this will also help to ascertain the exact OSC of the solid solution itself. In this research, the authors tried to clarify the above issues by characterizing the OSC performance on Ce-Zr solid solutions with Pt loading from 0.0001 to 10 wt%. We found that, increasing the Pt loading makes the oxygen storage and release rate higher. Temperature increase also makes the oxygen storage rate higher, however, the oxygen release rate is not affected by the temperature. The apparent OSC saturated above a certain level of Pt loading and temperature. The saturated OSC increased with increasing temperature.