THE SURFACE-CHEMISTRY OF ETHYL IODIDE ON HYDROGEN-COVERED NI(100) SURFACES

The reactivity of ethyl iodides on hydrogen predosed Ni(100) surfaces has been studied by using temperature programmed desorption (TPD) spectroscopy. The data show that hydrogen coadsorption inhibits the decomposition of ethyl groups at all coverages. Also, at ethyl iodide coverages below saturation, the yields of both ethylene and ethane (the products of beta-hydride and reductive elimination reactions respectively) increase equally with hydrogen coadsorption, but near saturation the desorption of ethane increases at the expense of ethylene production. A small amount of ethane is also produced via the hydrogenation of chemisorbed ethylene. This latter reaction occurs at higher temperature, which means that its activation energy is higher than that for the direct hydrogenation of the ethyl species. No coupling or H-D exchange reactions were observed in our experiments.