Carter, James, Althahban, Sultan, Nowicka, Ewa  ORCID: https://orcid.org/0000-0001-7449-2720, Freakley, Simon, Morgan, David John ORCID: https://orcid.org/0000-0002-6571-5731, Shah, Parag, Golunski, Stanislaw ORCID: https://orcid.org/0000-0001-7980-8624, Kiely, Christopher ORCID: https://orcid.org/0000-0001-5412-0970 and Hutchings, Graham John ORCID: https://orcid.org/0000-0001-8885-1560
2016.
Synergy and anti-synergy between palladium and gold in nanoparticles dispersed on a reducible support.
ACS Catalysis
6
(10)
, pp. 6623-6633.
10.1021/acscatal.6b01275
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Abstract
Highly active and stable bimetallic Au–Pd catalysts have been extensively studied for several liquid-phase oxidation reactions in recent years, but there are far fewer reports on the use of these catalysts for low-temperature gas-phase reactions. Here we initially established the presence of a synergistic effect in a range of bimetallic Au–Pd/CeZrO4 catalysts, by measuring their activity for selective oxidation of benzyl alcohol. The catalysts were then evaluated for low-temperature WGS, CO oxidation, and formic acid decomposition, all of which are believed to be mechanistically related. A strong anti-synergy between Au and Pd was observed for these reactions, whereby the introduction of Pd to a monometallic Au catalyst resulted in a significant decrease in catalytic activity. Furthermore, monometallic Pd was more active than Pd-rich bimetallic catalysts. The nature of the anti-synergy was probed by several ex situ techniques, which all indicated a growth in metal nanoparticle size with Pd addition. However, the most definitive information was provided by in situ CO-DRIFTS, in which CO adsorption associated with interfacial sites was found to vary with the molar ratio of the metals and could be correlated with the catalytic activity of each reaction. As a similar correlation was observed between activity and the presence of Au0* (as detected by XPS), it is proposed that peripheral Au0* species form part of the active centers in the most active catalysts for the three gas-phase reactions. In contrast, the active sites for the selective oxidation of benzyl alcohol are generally thought to be electronically modified gold atoms at the surface of the nanoparticles.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Research Institutes & Centres > Cardiff Catalysis Institute (CCI) Schools > Chemistry |
| Subjects: | Q Science > QD Chemistry |
| Uncontrolled Keywords: | ceria−zirconia; CO oxidation; formic acid; gold; gold−palladium alloy; palladium; water-gas shift |
| Publisher: | American Chemical Society |
| ISSN: | 2155-5435 |
| Funders: | European Research Council |
| Date of First Compliant Deposit: | 11 October 2016 |
| Date of Acceptance: | 29 August 2016 |
| Last Modified: | 05 Feb 2025 22:27 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/95295 |
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