J. Phys. Colloques
Volume 49, Numéro C6, Novembre 198835th International Field Emission Symposium / 35éme Symposium International d'Emission de Champ
|Page(s)||C6-215 - C6-220|
J. Phys. Colloques 49 (1988) C6-215-C6-220
KINETICS OF METHANOL DECOMPOSITION OF Rh(100) AND Rh(111) FIELD EMITTERSG.K. CHUAH1, N. KRUSE2, J.H. BLOCK2 et G. ABEND2
1 Department of Chemistry, National University of Singapore, Singapore
2 Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-1000 Berlin 33, F.R.G.
The decomposition of methanol on Rh has been investigated by means of pulsed field desorption mass spectrometry (PFDMS). lntermediates of the decomposition. CHxO (x = 1 - 3), are identified. By varying the temperature and reaction time it is possible to elucidate the elementary steps in methanol decomposition. A model based on a stepwise H-abstraction of the methoxy is postulated. The reaction becomes desorption-rate limited if the final products, CO(ad) and H(ad), are not removed from the surface and block sites required for reaction. However, by using a desorption field high enough to quantitatively remove the final products, the rate-determining step is found to be the removal of the H from the methoxy. Computer simulations support this observation.