HYDROGENATION OF OLEFINS ON ALUMINA .2. DEUTERATION AND EXCHANGE REACTIONS OF ETHYLENE

The hydrogenation of ethylene with deuterium has been carried out, respectively, on the weaker and the stronger active sites of alumina, which had been found previously with hydrogen to give different activity and kinetics for the reaction. It has been found that, on the weaker sites at low temperature, the main product is 1,2-ethane-d2 with a small amount of ethane-d3, while on the stronger sites at higher temperature, HD exchange of ethylene occurs much more quickly than hydrogenation and all deuteroethanes are produced. The results on the weaker sites have been successfully explained by a Twigg-Rideal mechanism. For the reactions on the stronger sites, however, a different mechanism is proposed, involving reaction of ethyl carbonium ions with hydrogen atoms formed by the dissociative adsorption of hydrogen on the weaker sites. © 1968.