Ethylene dehydrogenation to ethylidyne on Pt(111) studied by Cs+ reactive ion scattering. Evidence for an ethylidene intermediate

We studied dehydrogenation reaction of ethylene (C 2 H 4 ) on a Pt(1 1 1) surface using the technique of Cs + reactive ion scattering (RIS). Adsorption of ethyl iodide (C 2 H 5 I) on Pt(1 1 1) was also studied to provide the calibration data. The possible intermediate species in ethylene dehydrogenation to ethylidyne (C–CH 3 ), namely, ethylidene (CH–CH 3 ), vinyl (–CHCH 2 and CCH 2 ), and ethyl species (–CH 2 –CH 3 ), 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.