Molecular beam study of C2H4 oxidation on platinum: IR chemiluminescence of the CO and CO2 products

Abstract

Vibrationally excited CO and CO₂ molecules produced by the C₂H₄+ O₂ reaction on a Pt surface have been studied by IR emission spectroscopy. The selective production of syngas (CO + H₂) was observed from the partial oxidation reaction of ethene at high surface temperatures (> 1000K) even at an O₂ : C₂H₄ ratio of 3. The IR emission spectra of the product CO desorbed from the Pt surface showed that the CO molecules were vibrationally excited, but rotationally very cool. These results suggest that the dynamics of CO formation are similar to those for the partial oxidation of other hydrocarbons: CO formed by the surface reaction between C(ad) and O(ad) is desorbed without being thermally accommodated on the surface. CO₂ was formed at the higher O₂ : C₂H₄ ratio, and the analyses of the IR emission spectra showed that the dynamics of CO₂ formation may be different from those of catalytic oxidation of CO on the Pt surface.