Improved CO oxidation activity in the presence and absence of hydrogen over cluster-derived PtFe/SiO 2 catalysts

Attilio Siani, Burjor Captain, Oleg S. Alexeev, Eirini Stafyla, Ana B. Hungria, Paul A. Midgley, John Meurig Thomas, Richard D. Adams, Michael D. Amiridis

Research output: Contribution to journalArticle

66 Scopus citations

Abstract

The catalytic performance of cluster-derived PtFe/SiO 2 bimetallic catalysts for the oxidation of CO has been examined in the absence and presence of H2 (PROX) and compared to that of Pt/SiO 2- PtFe 2/SiO 2 and Pt;Fe 2/SiO 2 samples were prepared from PtFe 2(COD)(CO) 8 and Pt 5Fe 2(COD) 2(CO) 12 organometallic cluster precursors, respectively. FTIR data indicate that both clusters can be deposited intact on the SiO 2 support. The clusters remained weakly bonded to the SiO 2 surface and could be extracted with CH 2Cl 2 without any significant changes in their structure. Subsequent heating in H 2 led to complete decarbonylation of the supported clusters at approximately 350°C and the formation of Pt-Fe nanoparticles with sizes in the 1-2 nm range, as indicated by HRTEM imaging. A few larger nanoparticles enriched in Pt were also observed, indicating that a small fraction of the deposited clusters were segregated to the individual components following the hydrogen treatment. A higher degree of metal dispersion and more homogeneous mixing of the two metals were observed during HRTEM/XEDS analysis with the cluster-derived samples, as compared to a PtFe/SiO 2 catalyst prepared through a conventional impregnation route. Furthermore, the cluster-derived PtFe 2/SiO 2 and Pt 5Fe 2/SiO 2 samples were more active than Pt/SiO 2 and the conventionally prepared PtFe/SiO 2 sample for the oxidation of CO in air. However, substantial deactivation was also observed, indicating that the properties of the Pt-Fe bimetallic sites in the cluster-derived samples were altered by exposure to the reactants. The Pt 5Fe 2/SiO 2 sample was also more active than Pt/SiO 2 for PROX with a selectivity of approximately 92% at 50°C. In this case, the deactivation with time on stream was substantially slower, indicating that the highly reducing environment under the PROX conditions helps maintain the properties of the active Pt-Fe bimetallic sites.

Original languageEnglish (US)
Pages (from-to)5160-5167
Number of pages8
JournalLangmuir
Volume22
Issue number11
DOIs
StatePublished - May 23 2006
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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    Siani, A., Captain, B., Alexeev, O. S., Stafyla, E., Hungria, A. B., Midgley, P. A., Thomas, J. M., Adams, R. D., & Amiridis, M. D. (2006). Improved CO oxidation activity in the presence and absence of hydrogen over cluster-derived PtFe/SiO 2 catalysts. Langmuir, 22(11), 5160-5167. https://doi.org/10.1021/la053476a