Transformations of butenes on dehydroxylated Y zeolites studied by infrared spectroscopy

Abstract

Transformations of butenes on dehydroxylated Y zeolites were studied by i.r. spectroscopy. Oligomerization and isomerization reactions take place if the butenes are adsorbed at room temperature on these zeolites. It is concluded that Lewis acid sites are active in butene oligomerization on dehydroxylated zeolites. Their concentration and acid strength strongly influence the oligomerization rate. The adsorption of pyridine decreases the oligomerization rate and a zeolite in which 46% of the Lewis acid sites were removed by pyridine molecules was found to be inactive for the oligomerization reaction. The reactivity of the butenes in the oligomerization reaction increases in the order trans-but-2-ene < cis-but-2-ene < but-1-ene. This effect is explained by the influence of steric factors. At higher temperatures the oligomer undergoes further transformations.