Ethylene hydrogenation on a Rh(100) surface

Ultraviolet photoemission spectra from ethylene adsorbed at 80 K clearly show the presence of di-σ-bonded and π-bonded ethylene on clean and H-precovered Rh(100) surfaces, respectively. In temperature programmed reaction spectroscopy, one-third of this weakly adsorbed π-bonded ethylene is effectively hydrogenated to ethane below 200 K in contrast to the di-σ-bonded ethylene coadsorbed with hydrogen atoms. This is strong support for π-bonded ethylene as a primary intermediate in the reaction of ethylene hydrogenation.