Batch reaction of methanol and oxygen over TiO2 at 400 °C: Observing surface species by infrared spectroscopy, and gas species by mass spectroscopy

Batch reactions of methanol-oxygen mixtures have been studied over TiO/sub 2/ at 400/sup 0/C. Analysis of the combined infrared and mass spectroscopic results suggests the following reaction mechanism: chemisorption of methanol to form surface methoxy; hydrogen abstraction from surface methoxy to give surface hydroxyl and gas-phase formaldehyde; formaldehyde chemisorption to give surface formate; and surface formate decomposition by dehydrogenation giving H/sub 2/ and CO/sub 2/, and by dehydration giving H/sub 2/O and CO. Kinetic isotope effects present in reactant consumption, product formation, and surface species evolution support assignments of the rate-limiting step in the reaction sequence to hydrogen abstraction from the surface methoxy. 16 references, 3 figures.