A combination of surface spectroscopy and chemical reactivity studies was used to show that alkylidene groups, formed on β-Mo2C through the dissociative adsorption of ketones, are stable under ultrahigh vacuum conditions to anomalously high temperatures. Results are presented for cyclobutylidene, cyclopentylidene, and cyclohexylidene. Reflectance absorbance infrared spectroscopy in the CH2 stretching region, high-resolution X-ray photoemission measurements, labeled oxygen insertion, and metathesis reactions were used to detect surface alkylidenes at or above 900 K. The anomalous thermal stability of alkylidenes on the carbide surface shows that carbenes may be present on the carbide phase of Mo/ZSM-5 catalysts during the methane dehydroaromatization reaction. The latter reaction is typically carried out at approximately 970 K.

Atomic nitrogen and oxygen were deposited on -Mo 2 C through dissociative adsorption of NO. Reflectance absorbance infrared spectroscopy (RAIRS), thermal desorption, and synchrotron X-ray photoelectron spectroscopy (XPS) measurements were used to investigate the interplay between atomic nitrogen, carbon, and oxygen in the 400-1250 K region. The combination of the high resolution and high surface sensitivity offered by the synchrotron XPS technique was used to show that atomic nitrogen displaces interstitial carbon onto the carbide surface. Thermal desorption measurements show that the burnoff of the displaced carbon occurs at approximately 890 K. The incorporation of nitrogen into interstitial sites inhibits oxygen dissolution into the bulk. RAIRS spectroscopy was used to identify surface oxo, terminal oxygen, species formed from O 2 and NO on -Mo 2 C.