Ethylene dehydrogenation to ethylidyne on Pt(1 1 1) studied by Cs+ reactive ion scattering. Evidence for an ethylidene intermediate

We studied dehydrogenation reaction of ethylene (C2H4) on a Pt(1 1 1) surface using the technique of Cs+ reactive ion scattering (RIS). Adsorption of ethyl iodide (C2H5I) on Pt(1 1 1) was also studied to provide the calibration data. The possible intermediate species in ethylene dehydrogenation to ethylidyne (C–CH3), namely, ethylidene (CH–CH3), vinyl (–CHCH2 and CCH2), and ethyl species (–CH2–CH3), were closely investigated by RIS identification of surface molecules and temperature-programmed kinetic study. The result indicates that the dehydrogenation step occurs through an ethylidene intermediate and that vinyl and ethyl intermediates are not formed.