(157e) How Pt Interacts with CeO2 Under the Reducing and Oxidizing Environments at Elevated Temperature?

Platinum group metals (PGMs) are widely used as catalytically active phase in catalyst. Their unique electronic d-band structure allows them to be applied in many kinds of different reactions including CO oxidation, methane oxidation, hydrogenation, and water-gas shift reaction. PGMs should be highly dispersed on supports to increase the cost-effectiveness (catalytic activity/amounts) due to their expensiveness. When PGMs are dispersed on support, they interact electronically with each other, which brings about the physiochemical effects on their catalytic properties. In this regard, metal-support interaction (MSI) between PGM and support has been an interesting topic of many research groups for the past several decades.

It is known that the interaction between PGM and support affects the degree of sintering at high temperature, which remains a great challenge to make more durable catalysts. Especially, compared with Al₂O₃ support, PGM and ceria interact with each other more strongly, resulting in the higher PGM dispersion even after the high temperature treatment. Such strong interaction between impregnated PGM and ceria not only guarantees high metal dispersion but also can be beneficial for the catalytic reactions.

Hence, understanding the metal-ceria interaction is of practical importance to provide the rational design of ceria supported PGM catalysts. In the present research, the interaction between Pt and CeO₂ has been extensively investigated by combining various characterization methods including X-ray diffraction (XRD), N₂ adsorption/desorption (BET/BJH), H₂ temperature programmed reduction (TPR), pulsed and static CO-chemisorption, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and in-situ Raman spectroscopy. Especially, the effect of Pt-ceria interaction under the oxidizing/reducing environment on the thermal stability of Pt/CeO₂ catalyst has been focused in detail.