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.