HYDROGENATION OF ETHYLENE OVER SOME INTERMETALLIC COMPOUNDS

The hydrogenation of ethylene was studied by passing a mixture of ethylene and hydrogen over LaNi5, PrCo5, LaCo5, CeCo5, and SmCo5 in a temperature range from -85 to -46 °C. The reaction was also carried out over LaNi5H2.4, PrCo5H2.4, LaCo5H1.9, CeCo5H1.7, and SmCo5H1.2 by admitting only ethylene under similar conditions. It was found that the reaction proceeded at much higher rates over the hydrides than over their corresponding metal alloys. The rate of hydrogen desorption from the hydrides was separately measured, and the rate-determining step of hydrogenation over the hydrides was concluded to be the migration process of absorbed hydrogen atoms from the bulk of the compounds onto the surface. © 1979.