Strong Metal-Support Interactions between Copper and Iron Oxide during the High-Temperature Water-Gas Shift Reaction.

The commercial high-temperature water-gas shift (HT-WGS) catalyst consists of CuO-Cr2 O3 -Fe2 O3 , where Cu functions as a chemical promoter to increase the catalytic activity, but its promotion mechanism is poorly understood. In this work, a series of iron-based model catalysts were investigated with in situ or pseudo in situ characterization, steady-state WGS reaction, and density function theory (DFT) calculations. For the first time, a strong metal-support interaction (SMSI) between Cu and FeOx was directly observed. During the WGS reaction, a thin FeOx overlayer migrates onto the metallic Cu particles, creating a hybrid surface structure with Cu-FeOx interfaces. The synergistic interaction between Cu and FeOx not only stabilizes the Cu clusters, but also provides new catalytic active sites that facilitate CO adsorption, H2 O dissociation, and WGS reaction. These new fundamental insights can potentially guide the rational design of improved iron-based HT-WGS catalysts.