Alkali-Stabilized Pt-OH x Species Catalyze Low-Temperature Water-Gas Shift Reactions

Abstract

We report that alkali ions (sodium or potassium) added in small amounts activate platinum adsorbed on alumina or silica for the low-temperature water-gas shift (WGS) reaction (H₂O + CO → H₂ + CO₂) used for producing H₂. The alkali ion–associated surface OH groups are activated by CO at low temperatures (~100°C) in the presence of atomically dispersed platinum. Both experimental evidence and density functional theory calculations suggest that a partially oxidized Pt-alkali-O_x(OH)_y species is the active site for the low-temperature Pt-catalyzed WGS reaction. These findings are useful for the design of highly active and stable WGS catalysts that contain only trace amounts of a precious metal without the need for a reducible oxide support such as ceria.