Local structure of Pt species dictates remarkable performance on Pt/Al2O3 for preferential oxidation of CO in H2

Abstract

State-of-the-art production of industrial hydrogen predominantly derives from the reforming of hydrocarbons. However, the unavoidable ∼1 % CO in this hydrogen resource usually poisons proton-exchange-membrane fuel cells (PEMFCs) and other applications. An effective solution to eliminate CO involves the preferential oxidation of CO in H2-rich stream (PROX). Here, we report that ∼1.4 nm Pt nanoparticles supported on inert substrate (Al2O3) can catalyze total CO conversion and CO2 selectivity in a temperature range from −30 to 120 °C. Detailed characterizations indicate that this remarkable performance is determined by the local structure of Pt active centers. The ensemble of Pt(OH) and metallic Pt plays a more critical role compared with PtOx or the only Pt°. On this ensemble, O2 activation is favored while CO adsorption is weakened and H2 adsorption is inhibited, which facilitate the preferential oxidation of CO rather than H2, thus enabling a broad temperature window for 100 % selective CO removal.