Development of Oxygen Storage Material Using Sr–Ti-based Perovskite Unit

We have been developing new oxygen storage materials for application to automotive catalysts by designing perovskite oxides that utilize topochemical reactions, in which certain ions are inserted or substituted while maintaining the original crystal framework. Ti-doped SrFeO3–δ with the perovskite structure exhibits excellent oxygen storage properties and high chemical stability in the presence of CO2. The Pd/SrFe1–xTixO3–δ catalyst was effective for purifying automotive exhaust gases. Furthermore, transition metal-doped (Mn, Fe, and Co) SrTiO3 also exhibited oxygen storage properties based on topochemical reactions. The Pd catalyst supported on Co-doped SrTiO3, which had the best oxygen storage properties, achieved NO reduction through a Mars–van Krevelen mechanism involving oxygen vacancy sites in the perovskite unit. These results suggest that Sr–Ti perovskite unit is effective as a framework for oxygen storage materials with the high chemical stability which is important in practical applications, and that these materials can be applied as a catalyst support for automotive catalysts.