Adsorption and reaction of ethylene and hydrogen on Rh(100) surface

Adsorption and reaction of ethylene on clean and H-presaturated Rh( 100) ha ve been investigated using HREELS. Adsorption of ethylene on H-presaturated Rh(100) surface at 110 K leads to a pi-bonded state, as indicated by a pi sigma parameter of 0.39 equivalent to that of Zeise's salt. The formation o f an ethyl intermediate from the pi-bonded ethylene by insertion of preadso rbed H atom already takes place even at 110 K, leading to the evolution of ethane below 200 K. Upon heating, CC bond breakage is promoted on the H-pre adsorbed surface, where the strength of metal to H in the adsorbed ethylene is considered to be reduced by preadsorbed hydrogen. (C) 2000 Elsevier Sci ence B.V. All rights reserved.