Promoted ceria: A structural, catalytic, and computational study

Ramzi Farra, Max García-Melchor, Maik Eichelbaum, Maike Hashagen, Wiebke Frandsen, Jasmin Allan, Frank Girgsdies, L. Szentmiklósi, Núria López, Detre Teschner

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

The role of trivalent (La, Sm, Gd, and Y) and tetravalent (Hf, Zr, and Ti) dopants in the catalytic, structural, and electronic properties of ceria was investigated. Promoted ceria catalysts were synthesized by coprecipitation with ammonia and tested in HCl and CO oxidation. Ceria catalysts exhibit a medium high reactivity and excellent stability in HCl oxidation. The intrinsic reactivity of ceria in HCl oxidation can be improved by a factor of 2 when doping with Hf and Zr in appropriate quantities, whereas trivalent dopants are detrimental. Although both oxidation reactions rely on the existence of oxygen vacancies, the order of reactivity in HCl and CO oxidation is not completely parallel. The effects of promoters on the electronic conductivity and the vacancy formation energy were studied by contactless conductivity experiments using the microwave cavity perturbation technique and by density functional theory calculations. Furthermore, transport properties were also assessed on the basis of theoretical calculations. The order of oxygen vacancy formation energy follows well the order of conductivity (polaron mobility) (trivalent > tetravalent > undoped) observed under inert and oxidizing conditions. This implies that none of these properties correlates with the reactivity. On the other hand, reducing conditions strongly enhanced the conductivity of Hf- and Zr-doped ceria. In HCl oxidation, only the balanced reduction of both Cl and O vacancy formation energies allows for an enhanced reactivity. Promoters give rise to lattice contraction-expansion modifying vacancy formation energies, adsorption properties, and surface coverages.

Original languageEnglish
Pages (from-to)2256-2268
Number of pages13
JournalACS Catalysis
Volume3
Issue number10
DOIs
Publication statusPublished - Oct 4 2013

Fingerprint

Cerium compounds
Oxidation
Vacancies
Doping (additives)
Oxygen vacancies
Carbon Monoxide
Gene Conversion
Catalysts
Perturbation techniques
Coprecipitation
Ammonia
Crystal lattices
Electronic properties
Transport properties
Density functional theory
Structural properties
Microwaves
Adsorption
Experiments

Keywords

  • CeO
  • CO oxidation
  • conductivity
  • Deacon Reaction
  • DFT
  • dopants
  • HCl oxidation
  • PGAA
  • XRD

ASJC Scopus subject areas

  • Catalysis

Cite this

Farra, R., García-Melchor, M., Eichelbaum, M., Hashagen, M., Frandsen, W., Allan, J., ... Teschner, D. (2013). Promoted ceria: A structural, catalytic, and computational study. ACS Catalysis, 3(10), 2256-2268. https://doi.org/10.1021/cs4005002

Promoted ceria : A structural, catalytic, and computational study. / Farra, Ramzi; García-Melchor, Max; Eichelbaum, Maik; Hashagen, Maike; Frandsen, Wiebke; Allan, Jasmin; Girgsdies, Frank; Szentmiklósi, L.; López, Núria; Teschner, Detre.

In: ACS Catalysis, Vol. 3, No. 10, 04.10.2013, p. 2256-2268.

Research output: Contribution to journalArticle

Farra, R, García-Melchor, M, Eichelbaum, M, Hashagen, M, Frandsen, W, Allan, J, Girgsdies, F, Szentmiklósi, L, López, N & Teschner, D 2013, 'Promoted ceria: A structural, catalytic, and computational study', ACS Catalysis, vol. 3, no. 10, pp. 2256-2268. https://doi.org/10.1021/cs4005002
Farra R, García-Melchor M, Eichelbaum M, Hashagen M, Frandsen W, Allan J et al. Promoted ceria: A structural, catalytic, and computational study. ACS Catalysis. 2013 Oct 4;3(10):2256-2268. https://doi.org/10.1021/cs4005002
Farra, Ramzi ; García-Melchor, Max ; Eichelbaum, Maik ; Hashagen, Maike ; Frandsen, Wiebke ; Allan, Jasmin ; Girgsdies, Frank ; Szentmiklósi, L. ; López, Núria ; Teschner, Detre. / Promoted ceria : A structural, catalytic, and computational study. In: ACS Catalysis. 2013 ; Vol. 3, No. 10. pp. 2256-2268.
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