The role of copper in catalytic performance of a Fe–Cu–Al–O catalyst for water gas shift reaction

A Fe–Cu–Al–O water gas shift catalyst with a Fe : Cu atomic ratio of 4 : 1 upon pretreatment at 350 °C in H₂ exhibits a conversion higher than a physical mixture of Fe–Al–O and Cu–Al–O by ∼40% over a temperature range of 300 °C–450 °C. In situ ambient pressure X-ray photoelectron spectroscopy studies suggest that the surface region of Fe–Cu–Al–O was restructured into a double-layer structure consisting of a surface layer of Fe₃O₄ and a metallic Cu layer below it upon pretreatment at 350 °C. The strong metal (Cu)–oxide (Fe₃O₄) interface effect of this double layer structure enhances the catalytic activity of Fe₃O₄ in WGS.