Low-energy electron diffraction, work function charge and mass spectrometric studies of chemisorption and dehydrogenation of cyclohexane, cyclohexene and 1,3-cyclohexadiene on the Pt(111) surface

Abstract

Adsorption and reaction studies have been carried out using cyclohexane, cyclohexene, 1,3-cyclohexadiene, and benzene on the Pt(111) surface in order to determine the reactivity of the Pt(111) surface and to characterize stable surface species which occur during cyclohexane dehydrogenation. Cyclohexene is a long-lived surface species during the dehydrogenation of cyclohexane on the Pt(111) surface. Cyclohexane conversion to cyclohexene is not severely kinetically limited. Dehydrogenation of 1,3-cyclohexadiene to benzene proceeds rapidly to completion on the Pt(111) surface. The slow step in the dehydrogenation of cyclohexane to benzene appears to be the dehydrogenation of the cyclohexene intermediate. The cause of the slow reaction may be the orientation of the adsorbed cyclohexene relative to the catalyst surface.