An infrared spectroscopic study of CC bond-breaking during the thermal decomposition of the chemisorbed species from ethane on a Pt/SiO 2 catalyst

Abstract

Although many studies have been made on the infrared spectra of unsaturated hydrocarbons (alkenes, alkynes, and benzenes) and of cycloparaffins chemisorbed on metal surfaces, very few such studies have been made on adsorbed alkanes. In the pioneering era of such research, Eischens and Pliskin reported qualitatively that ethane adsorbed on Ni/SiO{sub 2} catalysts gave spectra similar to those from adsorbed ethylene on the hydrogen-free Ni surface, but very weak ones on the hydrogen-covered surfaces. Lee et al. have shown that methane molecules incident with high Kinetic energy chemisorb on Ni(111) to give surface methyl groups below 150 K. McDougall showed that ethane was chemisorbed at room temperature on a finely divided silica-supported platinum catalyst (EUROPT-1) and gave rise to a spectrum characteristic of surface ethylidyne groups CH{sub 3}CPt{sub 3}. Such surface species have previously been identified from the adsorption of ethene (ethylene) on various oxide-supported Pt catalysts and on Pt(111) and Pt(100) (5 x 20) single-crystal surfaces. In the present paper the authors report the effects of heating to 573 K from room temperature (294 K) on the surface species, including ethylidyne, derived from ethane chemisorbed on an impregnated finely divided Pt/SiO{sub 2} catalyst. Direct evidence is found for C-Cmore » bond-breaking processes.« less