Variations in the surface chemistry of methanol with CeO2(100) at low and elevated pressures

Abstract

The reactions of methanol with and without O2 were studied on a flat, highly crystalline CeO2(100) thin‐film surface with ambient pressure XPS. In the absence of O2, the ambient pressure XPS results indicate that in both low‐pressure (≤10−5 Torr) and high‐pressure regimes (≥10−1 Torr), the dominant surface species is methoxy. Methanol decomposition substantially reduces the ceria and CX deposit build‐up on the surface. When O2 is present, CX does not accumulate on the surface and the dominant surface species is different in the low‐pressure and high‐pressure regimes. Methoxy dominates at low pressure, while formate dominates at the higher pressure. The type of surface species appears to be related to the ability of O2 to fully oxidize the ceria surface during the methanol reaction.