Reaction of ethylene at the surface of liquid potassium

Abstract

The reaction of ethylene with liquid potassium has been investigated from 503 to 671 K by pressure changes and gas analysis as the metal is injected in to the gas by means of an electromagnetic pump. At the lower temperatures self hydrogenation occurs precisely according to 3C₂H₄→ 2C₂H₆+ 2C (or K₂C₂). The surface reaction is explained by dissociative adsorption of ethylene in to hydrogen adatoms which are subsequently employed in hydrogenation. With increasing temperature progressively less ethane is produced which is attributed to loss of hydrogen from the surface by solution in the metal. The Arrhenius plot for the reaction is not linear over the whole temperature range, a feature which is accounted for by differences in the rates of dissociation and hydrogenation.