Sintering and redispersion behavior of Pt on Pt/MgO

Sintering–redispersion of Pt and deterioration–regeneration of catalytic activity on Pt/MgO as automotive exhaust catalyst were studied. No Pt sintering was observed after air aging up to 1173 K. Pt L3-edge extended X-ray absorption fine structure results revealed the formation of an Mg2PtO4-like compound at the MgO surface and stabilization of oxidized Pt after air aging. Interaction between Pt and MgO involved in the formation of this Mg2PtO4-like compound likely provides an anchoring effect that prevents Pt sintering. After redox aging at 1073 K, Pt particles of ca. 20 nm were observed by X-ray diffraction and transmission electron microscopy (TEM). TEM images revealed that sintered Pt redispersed into smaller Pt particles of 2–5 nm on sequential oxidation–reduction treatment at 1073 K. Interactions involved in the formation of the Mg2PtO4-like compound should be the driving force for this redispersion. The redispersion behavior led to regeneration of the catalytic activity of Pt/MgO in a simulated automotive exhaust reaction.