TPD study of the adsorption and reaction of nitromethane and methyl nitrite on ordered Pt-Sn surface alloys

J. W. Peck, D. I. Mahon, D. E. Beck, Bruce E. Koel

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21 Scopus citations


The adsorption and reaction of the isomers nitromethane (CH3NO2) and methyl nitrite (CH3ONO) on two ordered Sn/Pt(111) surface alloys were studied using TPD, AES, and LEED. Even though the Sn-O bond is stronger than the Pt-O bond and Sn is more easily oxidized than Pt, alloying with Sn reduces the reactivity of the Pt(111) surface for both of these oxygen-containing molecules. This is because of kinetic limitations due to a weaker chemisorption bond and an increased activation energy for dissociation for these molecules on the alloys compared to Pt(111). Nitromethane only weakly adsorbs on the Sn/Pt(111) surface alloys, shows no thermal reaction during TPD, and undergoes completely reversible adsorption under UHV conditions. Methyl nitrite is a much more reactive molecule due to the weak CH3O-NO bond, and most of the chemisorbed methyl nitrite decomposes below 240K on the alloy surfaces to produce NO and a methoxy species. Surface methoxy is a stable intermediate until ∼300K on the alloys, and then it dehydrogenates to evolve gas phase formaldehyde with high selectivity against complete dehydrogenation to form CO on both alloy surfaces.

Original languageEnglish (US)
Pages (from-to)170-188
Number of pages19
JournalSurface Science
Issue number2-3
StatePublished - Aug 1 1998

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


  • Alloys
  • Auger electron spectroscopy (AES)
  • Chemisorption
  • Low energy electron diffraction (LEED)
  • Low index single crystal surfaces
  • Methylnitrite
  • Nitromethane
  • Platinum
  • Thermal desorption spectroscopy
  • Tin


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