Time evolution of palladium structure change with redox fluctuations in a LaFePdO3 perovskite automotive catalyst by high-speed analysis with in situ DXAFS

In the LaFePdO3 perovskite catalyst, redox fluctuations of the exhaust gas suppress the growth of particles of precious metal by causing Pd to move in and out of the perovskite crystal. To observe the real movements of Pd directly, the time evolution of local structure around Pd by redox fluctuations was investigated by in situ energy-dispersive X-ray absorption fine-structure (DXAFS) analysis with a 10 ms resolution. We proved that the change in structure of Pd is sufficiently fast to respond to the control frequency (1–4 Hz) of an actual gasoline engine and that the Pd particles that segregate out are extremely fine.