CeO2/Pt/Al2O3 catalysts for the WGS reaction: Improving understanding of the Pt-O-Ce-Ox interface as an active site

• Published in: Applied catalysis. B, Environmental Vol. 325; p. 122361
• Main Authors: Borges, Laís Reis, Braga, Adriano H., Zanchet, Daniela, Gallo, Jean Marcel R., Bueno, José Maria C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2023
• Subjects: Cl poisoning; Heterogeneous catalysis; Pt-Ce interface; Pt-ceria catalysts; Water-gas shift reaction; Pt-Ce interface; Heterogeneous catalysis; Cl poisoning; Water-gas shift reaction; Pt-ceria catalysts
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2023.122361

In this work, we demonstrate that knowledge of the structural parameters of Pt nanoparticles (PtNp) supported on ceria/alumina is essential for understanding the surface structure, the electronic properties of PtNp, and the effect of ceria on the catalytic activity in the water-gas shift reaction. The similar Pt-Pt and Pt-O bond distances for different PtNp sizes suggested similar electronic density of the Pt sites, indicating that changes of the electronic properties of the Pt sites, due to the size effect, were compensated by the presence of Pt-O species. The turnover frequency based on Pt0 sites varied between 2 and 10 times higher, compared to unpromoted catalysts, and was dependent on the PtNp size and morphology, which determined the density of oxygen on the surface and the density of Pt-O-Ce sites. The effect of ceria in increasing the activity could be explained by the creation of active Pt-O-Ce sites at the surface. [Display omitted] •The PtO on the surface resulted in a compensation effect between Pt core size and oxygen coverage.•Contraction of the Pt−Pt bond lengths, by presence of PtO, was not observed with decrease of Pt size.•With the addition of ceria, part of the local Ptx-O structure was modified to Ptx-O-Ce species.•The reaction rate (µmolCO s−1 gPt−1) was correlated with the density of Pt-O-Ce sites.