Sulfur induced selectivity changes for methanol decomposition on Ni(100)

The adsorption and reactions of methanol on Ni(100), Ni(100)p(2 × 2)S and Ni(100) c(2 × 2)S were studied by temperature programmed reaction spectroscopy. On the clean surface mixed isotopes of dihydrogen and CO were formed in desorption-limited processes above 300 K. Evidence suggestive of the existence of an adsorbed [COD] intermediate was obtained. Similar results were found on the p(2 × 2)S surface. The sulfur decreased the amount of adsorbed methanol which reacted, and it interacted significantly with the high temperature binding state of deuterium produced by decomposition of the [COD] intermediate. On the c(2 × 2)S structure the primary reaction intermediate was methoxy, CH3O. Formaldehyde was formed with an activation energy of 26 kcalgmol. No desorption-limited CO was observed. These results clearly demonstrate the role of structural overlayers in selective poisoning.