Nature of Reactive Oxygen Intermediates on Copper-Promoted Iron–Chromium Oxide Catalysts during CO<sub>2</sub> Activation
Minghui Zhu, Pengfei Tian, Michael E. Ford, Jiacheng Chen, Jing Xu, Yi‐Fan Han, Israel E. Wachs
Abstract
A series of copper-promoted iron–chromium oxide catalysts with various copper loadings are investigated for CO2 activation (reverse water–gas shift reaction) to determine the nature of surface oxygen intermediates involved in this redox reaction. Using a series of in situ characterizations (XPS, HS-LEIS, DRIFTS, and EXAFS), H2-TPR, and transient kinetic analysis, two reactive surface oxygen species with different reduction characteristics are identified for catalysts during the reaction. The more abundant and more active surface oxygen species are closely related to the surface hydroxyls located at the Cu-Fe3O4 interfacial regions. A direct correlation of the CO2 hydrogenation reaction rate with both the number and reduction kinetics of the more active surface oxygen intermediates is established.