Chinese Journal of Catalysis ›› 2026, Vol. 82: 327-336.DOI: 10.1016/S1872-2067(25)64900-X

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Shielding active Fe oxide by surface oxide overlayers for harsh high-temperature water-gas shift reaction

Rongtan Li, Xiangze Du, Xiaohui Feng, Jianyang Wang, Na Ta, Qiang Fu*(), Xinhe Bao*()   

  1. State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
  • Received:2025-08-10 Accepted:2025-09-18 Online:2026-03-18 Published:2026-03-05
  • Contact: * E-mail: qfu@dicp.ac.cn (Q. Fu),xhbao@dicp.ac.cn (X. Bao).
  • Supported by:
    National Key R&D Program of China(2021YFA1502800);National Key R&D Program of China(2022YFA1504800);National Key R&D Program of China(2022YFA1504500);National Natural Science Foundation of China(22332006);National Natural Science Foundation of China(22288201);National Natural Science Foundation of China(22321002);National Natural Science Foundation of China(22402194);Dalian Innovation Support Plan for High Level Talents(2023RG002);Photon Science Center for Carbon Neutrality;Fundamental Research Funds for the Central Universities(20720250005);China Postdoctoral Science Foundation(2023M743425);China Postdoctoral Science Foundation(2025T180267)

Abstract:

Oxide supports are well known to significantly influence the structure and properties of active oxide overlayers through strong oxide-support interactions. However, the effect of oxide overlayers on the underlying active oxide substrates remains poorly understood. Here, we report the controllable formation of ceria (CeO2) overlayers on a hematite (Fe2O3) surface (CeO2/Fe2O3) via a melting-wetting method. Submonolayer CeO2 patches facilitate the partial reduction of surrounding Fe2O3 to active magnetite (Fe3O4) while effectively suppress further reduction of Fe3O4 to inactive metallic iron (Fe0) under harsh high-temperature water-gas shift (HT-WGS) conditions. We demonstrate this stabilization effect of surface oxide patches (MOx, M = Ce, Cr, Mn, Mg, Al and Zn) on surrounding active Fe oxide sites via creating a shielding zone around each oxide patch. As a result, Fe2O3 catalysts covered with a small amount of CeO2 surface overlayers (~1.8 wt%) exhibit remarkable stability at 450 °C for over 100 h, in contrast to rapid deactivation observed in pure Fe2O3 and industrial iron-chromium (6.5 wt% Cr) catalysts. Building on these findings, we have developed an advanced HT-WGS process that utilizes Cr-free catalysts and significantly reduces steam consumption. This study highlights the critical role of surface oxide overlayers in modulating the redox behavior and reactivity of underlying active oxide substrates, developing an interface confinement strategy for the design of robust and efficient oxide catalysts.

Key words: Surface oxide overlayers, Strong oxide-support interaction, Interface confinement effect, Fe2O3, High-temperature water-gas shift