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Reversible and Irreversible Structural Changes in Cu/ZnO/ZrO2 Catalysts during Methanol Synthesis
Lucas Warmuth1, Matthias Steurer1, Dieter Schild2
1Institute of Catalysis Research and Technology (IKFT), Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen, Germany.
ACS Applied Materials & Interfaces
|February 9, 2024
Summary
Catalyst deactivation in methanol synthesis is primarily caused by copper sintering and zinc oxide restructuring. Reactivation efforts partially restore catalyst structure, highlighting the promoter role of zirconia.
Area of Science:
- Materials Science
- Catalysis Science
- Chemical Engineering
Background:
- Operational stability of heterogeneous catalysts is intrinsically linked to their structure and chemical state.
- Precise understanding of these relationships is crucial for advancing catalyst development in industrial processes.
Purpose of the Study:
- To investigate the deactivation mechanisms of a Cu/ZnO/ZrO2 catalyst used in methanol synthesis.
- To analyze the time-dependent structural and chemical changes occurring during catalyst aging.
- To evaluate the effectiveness of reductive reactivation on aged catalysts.
Main Methods:
- Time-resolved experiments using a parallel setup.
- Characterization techniques including X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), N2 physisorption, and transmission electron microscopy (TEM).
- Analysis of catalyst samples aged for different durations (0, 50, 935 hours on stream).
Main Results:
- Catalyst deactivation is primarily attributed to the sintering of copper (Cu0) domains and restructuring within zinc oxide (ZnO) domains.
- Reductive reactivation using H2/N2 partially restores the catalyst's structural integrity.
- Zirconia (ZrO2) acts as a promoter, and redispersion of zirconia is observed following initial reduction.
Conclusions:
- Sintering and restructuring are key deactivation pathways for Cu/ZnO/ZrO2 methanol synthesis catalysts.
- Limited structural recovery is achieved through reductive reactivation.
- The promoter role of ZrO2 and its redispersion are significant aspects of catalyst behavior.
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