Živković, A., Solsona-Delgado, V., van der Linden, B. et al. (2 more authors) (2023) Molecular-level understanding of interfacial carbonates in stabilizing CuO-ZnO(Al2O3) catalysts. Journal of Catalysis, 425. pp. 406-421. ISSN 0021-9517
Abstract
A descriptor of active CuO-ZnO(Al2O3) methanol-synthesis and water–gas-shift catalysts is the presence of high-temperature carbonates (HT-CO3) in the oxidic catalyst precursor. Previous reports have shown that such HT-CO3 lead to an appropriate interaction between the oxides; as a result, a high Cu surface area (or Cu-Zn or Cu/ZnO interphase areas) can be achieved. Yet, their nature is not well understood. In this study, the nature of these carbonates was investigated by experimental and theoretical methods in the oxidic precatalyst. A calcined Cu-Zn-Al hydrotalcite model compound revealed to have well-dispersed ZnO and CuO phases, together with highly stable HT-CO3. It was hypothesized that these HT-CO3 groups may be placed at critical locations at nano-scale as a glue, thus avoiding the growth of the oxide crystallites during calcination. This is an excellent pre-condition to achieve a high Cu surface area (or Cu-Zn or Cu/ZnO interphase areas) upon reduction, and therefore a high activity. To prove that, first-principles calculations were carried out based on the density functional theory (DFT); alumina was not considered in the model as the experimental data showed it to be amorphous but it may still have an effect. Comprehensive calculations provided evidence that such carbonate groups favourably bind the CuO and ZnO together at the interface, rather than being isolated on the individual oxide surfaces. The results strongly suggest that the HT-CO3 groups are part of the structure, in the calcined precatalyst, where they would prevent thermal sintering through a bonding mechanism between CuO and ZnO particles, which is a novel interpretation of this important catalyst descriptor.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | Methanol synthesis catalysts, CuO-ZnO catalysts, High-temperature-carbonate descriptor, Thermal sintering, Structural stability, First-principles calculations |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 04 Aug 2023 08:31 |
Last Modified: | 04 Aug 2023 08:31 |
Published Version: | https://www.sciencedirect.com/science/article/pii/... |
Status: | Published |
Publisher: | Elsevier BV |
Identification Number: | 10.1016/j.jcat.2023.06.032 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:202116 |
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