Determination of the active site and mechanism for alkene isomerization in CuII exchanged Y-type zeolite

Abstract

Reactions of CD₂CH—CH₃, but-1-ene and 3,3-dimethylbut-1-ene have been studied over a Y-type zeolite containing ∼4 Cu^II per unit cell. Kinetic induction periods, associated with the generation of active sites by Cu^II reduction, were only observed for the deuterium redistribution reactions of CD₂CH—CH₃. Nevertheless, arguments are presented to show that such generation of active sites is central to alkene isomerization reactions over Cu^II exchanged X- and Y-type zeolites. The mechanism of alkene isomerization is shown to require carbonium ions, generated from protons produced following Cu^II reduction by the alkene.