In order to probe the thermal stability and reactivity of ethyl intermediates on Pt-Sn alloy catalysts, we have synthesized these species by reaction of H atoms with adsorbed ethylene on a (√3 × √3)R30°-Sn/Pt(111) surface alloy. Adsorbed ethyl groups are stable until 376 K where they react to evolve ethane, ethylene, and H2. The activation energy for ethyl dehydrogenation is Edehyd** = 97 kJ/mol, which is twice that reported on Pt(111). In addition, we place a lower limit of Ehydr* > 70 kJ/mol on the barrier to ethyl hydrogenation on this alloy.
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