Adsorption of cyclic hydrocarbons on Pt and the interaction of the adsorbed species with hydrogen

The adsorption of six-membered hydrocarbon cycles and cyclopentane and the interaction of hydrogen with the adsorbed layer on polycrystalline Pt-foil have been studied. The work function change (Dw) was followed by a Kelvin probe and the C/Pt peak ratio was determined by Auger electron spectroscopy. Combining these two techniques made it possible to distinguish between chemisorption via s-bonds and p-complex formation. Benzene and toluene adsorbed first as p-complex while cyclohexane showed initially a partial aromatization and a p-complex-like bonding to the surface. Excess hydrocarbon or addition of hydrogen transformed the p-complex into s-bonded species. Cyclopentane adsorbed via s-bonds and showed no significant hydrogen effect.