A VIBRATIONAL SPECTROSCOPIC STUDY OF THE ADSORPTION AND DEHYDROGENATION OF CYCLIC C-6 HYDROCARBONS ON THE (1X1) AND (5X20) SURFACES OF PT(100)

The dehydrogenation of cyclohexane and cyclohexene has been investigat ed on the (1 x 1) and (5 x 20) surface modifications of Pt{100}. In ea ch case dehydrogenation to adsorbed benzene occurs, although the react ion has a very low probability for cyclohexane adsorbed on the (5 x 20 ) surface at low temperature, despite the presence of softened C-H str etching modes in the vibrational spectra. The surface electronic struc ture appears to influence the reaction pathway of the dehydrogenation process. On the (5 x 20) surface a conformational change of the adsorb ate appears to occur, while on the (1 x 1) surface a stable intermedia te can be isolated. Measurements made on isomers of cyclohexadiene sup port the suggestion that this intermediate has the formula C6H9. (C) 1 997 Elsevier Science B.V.