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

Abstract

The reactions of methanol with and without O 2 were studied on a flat, highly crystalline CeO 2 (100) thin-film surface with ambient pressure XPS. In the absence of O 2 , 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 C X deposit build-up on the surface. When O 2 is present, C X does not accumulate on the surface and the dominant surface species is different in the low-pressure and highpressure 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 O 2 to fully oxidize the ceria surface during the methanol reaction.

Ceria-Based Catalysts Studied by Near Ambient Pressure X-ray Photoelectron Spectroscopy: A Review

“…Acidic materials yield coupling products such as dimethyl ether, basic materials cause dehydrogenation with CO and CO 2 as products, and redox catalysts produce formaldehyde. Very recently, Mullins [156] reported the reaction of methanol with and without O 2 on a flat and highly crystalline CeO 2 (100) surface as a function of temperature and pressure, via ambient pressure XPS. The results indicated that, in the absence of O 2 , methoxy (CH 3 O-) is the prevailing surface species in both low-pressure (≤ 1.3 × 10 -5 mbar) and high-pressure regimes (≥ 0.13 mbar).…”