Observation of a deuterium kinetic isotope effect in the chemisorption and reaction of methanol on Ni(111)

• Published in: Surface science 1984-01, Vol.146 (1), p.199-210
• Main Authors: Gates, S.M., Russell, J.N., Yates, J.T.
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solid-gas interface; Surface physical chemistry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(84)90237-1

Measurements of the reactive sticking coefficient, S R 0, under zero coverage (irreversible) conditions for the reaction of methanol with a clean Ni(111) surface have revealed a significant deuterium kinetic isotope effect. S R 0 measured for CH 3OH and CD 3OH are equal, and are about 1.61 to 1.35 times greater than 5 R 0 for CH 3OD, in the temperature range 290–400 K. The ratio S R 0( OH) S R 0 ( OD) decreases monotonically from 1.35 to 1.10 in the temperature range 400 to 500 K. The measurements support the rate-controlling formation of adsorbed methoxy, CH 3O (ads), as an unstable surface intermediate in the decomposition of methanol to CO and H 2. These observations indicate that the deuterium kinetic isotope effect may be a generally useful tool for determining the reaction site location on a molecule interacting with a surface.