In Situ and Simultaneous Observation of Palladium Redox and Oxygen Storage/Release in Pd/Sr–Fe–O Perovskite Catalysts Using Dispersive XAFS

We have succeeded in in situ and simultaneously observing the redox reaction of palladium and the oxygen storage/release process in a newly developed palladium-promoted SrFeO (Pd/SrFeO) catalyst during redox-gas cycles using dispersive X-ray absorption fine structure (XAFS) analysis at 673 K with a time resolution of less than 20 ms.The Pd/SrFeO catalyst, which exhibits high performance for automotive emission control, has a unique "multi-phase-domain" structure, where a single grain is composed of nano-sized domains of three phases: SrFeO 3¹¤ , Sr 4 Fe 6 O 13¹¤ and SrFe 12 O 19¹¤ .In situ observation has shown a strong correlation between the redox of the palladium and the oxygen storage/release in the Pd/SrFeO catalyst, and the correlation factors differ between the reduction and oxidation reactions.The oxide phases exhibit a type of "oxygen buffer" effect in the oxidation cycle and delay the formation of PdO, resulting in the high performance of the catalyst.