MAGNETIC-RESONANCE STUDIES OF PROPENE ADSORPTION ON ALUMINA-SUPPORTEDPLATINUM SURFACES

Carbon-13 and deuterium magnetic resonance data for propene adsorbed o n high dispersion, alumina-supported platinum surfaces were obtained a fter adsorption at various temperatures and thermal treatments. Propen e labeled with carbon-13 in the 1-position was found to scramble to th e 3-position after exposure to 5% Pt/Al2O3, suggesting the formation o f a short-lived propene allyl species. This species converts to a stro ngly adsorbed di-sigma-bonded configuration. Upon warming to 323 K, ad sorbed propene is partially converted to propylidene. Our results indi cate that propylidene decomposes to dehydrogenated surface carbon at e levated temperatures; neither ethylidene nor ethylidyne forms as a con sequence of this decomposition.