Selectivity changes due to restructuring of the Pt(533) surface in the NH3 + O2 reaction

A. Scheibe, S. Günther, R. Imbihl

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19 Scopus citations


Ammonia oxidation with oxygen over Pt(533) in the pressure range 10 -7-10-3mbar has been studied using LEED and scanning tunneling microscopy (STM) to detect reaction-induced structural changes. Below 620 K, strong hysteresis effects in the rate occur upon cyclic variation of one of the p, T parameters. The rate changes are associated with structural modifications of the substrate. The Pt(533) surface exhibiting single atomic steps after preparation undergoes a doubling in step height and terrace width connected with a shift in selectivity from preferential N2 production to strong NO formation. Restoring the single atomic steps in vacuum requires heating above 1100 K, but under reaction conditions the substrate changes are reversible at least down to 600 K.

Original languageEnglish
Pages (from-to)33-37
Number of pages5
JournalCatalysis Letters
Issue number1-3
StatePublished - Mar 2003
Externally publishedYes


  • Ammonia oxidation
  • Catalyst restructuring
  • Hysteresis effects
  • Scanning tunneling microscopy
  • Stepped Pt surface


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