DIFFERING CHARACTERISTICS OF CU AND ZNO IN DEHYDROGENATION OF ETHANOL - A DEUTERIUM-EXCHANGE STUDY

Abstract

Direct evidence for the differing characteristics of Cu and ZnO in the dehydrogenation of ethanol were provided through the deuterium exchange reaction of ethanol and acetaldehyde. Deuterium was mainly exchanged at the alpha-carbon of ethanol and acetaldehyde on Cu catalyst. On the other hand, deuterium was mainly exchanged at the beta-carbon on ZnO catalyst. More deuterium atoms were exchanged with D2 than with D2O on Cu catalyst, but the reverse results were obtained on ZnO catalyst. Beta-Elimination type reaction mechanisms are suggested for the dehydrogenation of ethanol, and a beta-carbanionic intermediate was proposed for the dehydrogenation of acetaldehyde.