A comparative surface science study of carbide and oxycarbide: the effect of oxygen modification on the surface reactivity of C/W(1 1 1)

The dehydrogenation of cylohexene to benzene has been used as a probe reaction to study the properties of oxygen-modified C/W(1 1 1) surfaces by temperature programmed desorption, Auger electron spectroscopy and high-resolution electron energy loss spectroscopy. The reactivity of oxygen-modified C/W(1 1 1) depends strongly on the temperature at which the C/W(1 1 1) surface is exposed to oxygen. The oxygen-modified C/W(1 1 1) surface, after exposing to oxygen at 900 K, promotes the selective dehydrogenation of cyclohexene to benzene. The selectivity to benzene on this surface is ∼83%, which is slightly higher than that observed on unmodified C/W(1 1 1) and on Pt(1 1 1). In contrast, oxygen-modified C/W(1 1 1) surfaces with low temperature (