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

Abstract

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.