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<p>Cu/ZnO/Al<sub>2</sub>O<sub>3</sub> catalysts are the industrial standard for methanol synthesis. Their high activity stems from the synergy between Cu and Zn, but their precise structure under CO<sub>2</sub> hydrogenation conditions remains unknown. Here we show, using operando transmission electron microscopy, that the formation of ZnO<sub><i>x</i></sub> overlayers and CuZn surface alloys on Cu surfaces can be reversible and is mediated by the operating temperature and the chemical potential of the gas phase. Lower temperatures and more oxidative conditions lead to thicker ZnO<sub><i>x</i></sub> overlayers. At elevated temperatures, the overlayer coverage opens, exposing Cu nanoparticle surfaces to the feed and enabling CO<sub>2</sub> activation. Furthermore, we show that CuZn alloys are transient species and are re-oxidized by H<sub>2</sub>O formed during the reaction. This implies that, in CO<sub>2</sub> hydrogenation conditions, CuZn and Cu–ZnO surface states may coexist and continuously convert into one another as the local chemical potential oscillates throughout steady-state operation. Maintaining this fluctuation might be critical to the lifetime and performance of the catalyst.</p><p></p>

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Dynamics of a Cu/ZnO/Al2O3 catalyst revealed by operando transmission electron microscopy during CO2 hydrogenation

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年4月1日

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  • Maxime Boniface,
  • Thomas Götsch,
  • Jinhu Dong,
  • Jutta Kröhnert,
  • Elias Frei,
  • Annette Trunschke,
  • Robert Schlögl,
  • Beatriz Roldan Cuenya,
  • Thomas Lunkenbein

摘要

Cu/ZnO/Al2O3 catalysts are the industrial standard for methanol synthesis. Their high activity stems from the synergy between Cu and Zn, but their precise structure under CO2 hydrogenation conditions remains unknown. Here we show, using operando transmission electron microscopy, that the formation of ZnOx overlayers and CuZn surface alloys on Cu surfaces can be reversible and is mediated by the operating temperature and the chemical potential of the gas phase. Lower temperatures and more oxidative conditions lead to thicker ZnOx overlayers. At elevated temperatures, the overlayer coverage opens, exposing Cu nanoparticle surfaces to the feed and enabling CO2 activation. Furthermore, we show that CuZn alloys are transient species and are re-oxidized by H2O formed during the reaction. This implies that, in CO2 hydrogenation conditions, CuZn and Cu–ZnO surface states may coexist and continuously convert into one another as the local chemical potential oscillates throughout steady-state operation. Maintaining this fluctuation might be critical to the lifetime and performance of the catalyst.