KINETICS OF METHANOL DECOMPOSITION OF Rh(100) AND Rh(111) FIELD EMITTERS

The decomposition of methanol on Rh has been investigated by means of pulsed field desorption mass spectrometry (PFDMS). Intermediates of the decomposition. CH,O (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 i f 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.