Activation and deactivation of the commercial‐type CuO–Cr2O3–Fe2O3 high temperature shift catalyst.

This work elucidates the structural evolution of a commercial‐type iron oxide‐based high temperature water–gas shift (HT‐WGS) catalyst during activation and deactivation stages. The findings highlight the importance of Cu–FeOx interfaces. Based on the new insights, future improvement of commercial iron‐based catalysts should focus on stabilization of the active Cu–FeOx interface. Much effort has been devoted to understanding the structure, mechanism, and promotion of the commercial‐type CuO–Cr2O3–Fe2O3 catalyst for the high temperature water–gas shift (HT‐WGS) reaction. However, structural evolution of the catalyst during the activation and deactivation stages was rarely reported. Herein, catalyst characterization, temperature‐programmed studies, and kinetic analysis were conducted on iron oxide‐based HT‐WGS catalysts. Addition of Cu was found to accelerate both the bulk (Fe2O3 → Fe3O4) and surface (active FeOx–Cu interface) transformations during the catalyst activation stage. During catalyst deactivation, Cu accelerated both sintering of the Fe3O4 bulk phase and unfavorable encapsulation of the metallic Cu particles with a substantial FeOx overlayer. The loss of the initial active Cu–FeOx interfacial sites reversed the promotional effect of Cu. [ABSTRACT FROM AUTHOR]