Reaction of methanol with TiC and VC (100) surfaces

The reaction of methanol on the (100) surfaces of single crystal vanadium carbide (VC) and titanium carbide (TiC) has been studied using high resolution electron energy loss spectroscopy (HREELS), temperature programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). Methanol forms a mixed monolayer of molecular methanol and a methoxy intermediate upon adsorption at 153 K on both VC(100) and TiC(100). With increasing temperature, methanol is evolved from both surfaces through molecular and recombinative desorption. Approximately half of the methoxy intermediate reacts with the VC surface to produce formaldehyde and hydrogen, with a small amount of methane and persistent oxygen surface species. By contrast. very little of the methoxy intermediate reacts with the TiC surface, producing methane and hydrogen. A model of the surface reactions has been constructed based upon differences in the electronic structures of the carbide substrates.