Pd-Ce-Ox species on MWCNTs surface: Probing the structure-activity correlation in low-temperature CO oxidation

• Published in: Applied surface science 2023-02, Vol.611, p.155750, Article 155750
• Main Authors: Kibis, Lidiya S., Zadesenets, Andrey V., Garkul, Ilia A., Korobova, Arina N., Kardash, Tatyana Yu, Fedorova, Elizaveta A., Slavinskaya, Elena M., Stonkus, Olga A., Korenev, Sergey V., Podyacheva, Olga Yu, Boronin, Andrei I.
• Format: Article
• Language: English
• Subjects: Ceria; Metal-support interaction; MWCNTs; Palladium; Wet CO oxidation
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.155750

Herein, the highly dispersed palladium and ceria species were deposited on the surface of multi-walled carbon nanotubes (MWCNTs) by co-deposition from acetone solutions. The use of MWCNTs allowed varying Pd/Ce atomic ratio in a wide range, while maintaining a high dispersion of the active components. Application of physicochemical methods revealed the formation of various palladium species. Single Pd2+ ions dispersed in CeO2 lattice were the main Pd-Ce-Ox species at low Pdat/Ceat ratio. With an increase of the Pd content in the samples the preferential formation of PdO particles in a tight contact with CeO2 nanoparticles was observed. The size of PdO and CeO2 primary particles was in a range of 1–5 nm. The Pd-Ce-Ox/MWCNTs samples showed high activity in the CO oxidation reaction already at room temperature with a temperature of 50% CO conversion below 100 °C. The Pd2+-CeO2 and PdO-CeO2 species demonstrated the comparable activity in “dry” CO oxidation. However, the presence of water vapor in the reaction mixture resulted in the immediate deactivation of Pd2+-CeO2 species, while PdO-CeO2 species retained a high activity at 20°С. The results of the work highlight the benefits of MWCNTs, Pd, and CeO2 combination for obtaining catalysts highly active in CO oxidation. [Display omitted] •MWCNTs provide stabilization of highly-dispersed palladium and cerium species.•Pd2+ ions stabilized in CeO2 lattice are formed at low Pd/Ce atomic ratio.•Increase of Pdat/Ceat ratio leads to predominant formation of PdO-CeO2 aggregates.•PdO-CeO2/MWCNTs are highly active in “wet” CO oxidation at room temperature.