Surface speciation and alkane oxidation with highly dispersed Fe(III) sites on silica

Dario Prieto-Centurion, Justin M. Notestein

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


When highly dispersed, supported Fe oxides are selective alkane oxidation catalysts, but new syntheses are required to reliably produce such materials. Here, highly dispersed, supported Fe3+ catalysts are prepared via incipient wetness impregnation of SiO2 with aqueous Fe complexes of ethylenediaminetetraacetic acid (FeEDTA), followed by calcination. With Na + countercations, UV-visible diffuse reflectance spectra are entirely below 300 nm and H2 temperature-programmed reduction only shows reduction at ∼630 °C for all loadings up to 2.15 wt%, the maximum loading for a single impregnation cycle. These characteristics indicate isolated sites not seen for Fe(NO3)3 precursors even at 0.3 wt%. NH4+ countercations lead to amorphous oxide oligomers and a minority species with unusual reducibility at 310 °C. Na+ countercations produce 'single-site' behavior in adamantane oxidation using H2O2 with a specific turnover frequency of 9.2 ± 0.8 ks-1, constant for all Fe loadings and approximately 10 times higher than that of other well-dispersed Fe/SiO2 materials. Similar turnover frequencies are obtained when counting only the highly reducible species on the NH4+-derived catalyst, allowing these sites to be tentatively assigned as small, undercoordinated clusters that are both easily reduced and participate in alkane oxidation, reminiscent of Fe-exchanged MFI zeolites.

Original languageEnglish (US)
Pages (from-to)103-110
Number of pages8
JournalJournal of Catalysis
Issue number1
StatePublished - Apr 1 2011


  • C-H bond activation
  • EDTA ligand
  • Isolated site
  • Single-site catalyst
  • Supported oxide

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry


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