Pt nanoparticles encapsulated in CeO₂ over-layers synthesized by controlled reductive treatment to suppress CH₄ formation in high-temperature water-gas shift reaction

Pt supported on CeO₂ (Pt/CeO₂) is known to be a good catalyst for the water-gas shift (WGS) reaction. However, Pt catalyzes the methanation reaction as a side reaction, which limits the usefulness of Pt/CeO₂ as a catalyst in the high-temperature (HT) WGS reaction. In this study, Pt nanoparticles (Pt NPs) were encapsulated in CeO₂ over-layers (‘Pt in CeO₂’) by using controlled reductive treatments to suppress the methanation reaction on Pt NPs. ‘Pt in CeO₂’ catalyst demonstrated the much lower CH₄ selectivity while showing the same high activity in the HT-WGS reaction compared to the conventional ‘Pt on CeO₂’ catalyst. Detailed characterizations revealed that the underlying Pt NPs promoted the WGS reaction on thin (<1 nm) CeO₂ over-layers by facilitating the formation of active oxygen vacancies. The present contribution to catalyst modification via simple thermal treatments will provide additional way to control metal-support interactions to improve catalytic performance.