Transient diffusion, desorption, and reaction studies of cyclopropane and propylene with NaX and Eu/NaX zeolites

Abstract

The exchange of Eu3+ for Na+ cations into the sodalite cages of X zeolite (Eu25Na11X) leads selectively to the isomerization reaction of cyclopropane to propylene. The latter reaction is catalyzed by Brønsted acid sites with an apparent activation energy of 10.6 kcal/mol. Sorption measurements of cyclopropane and propylene with Eu/NaX and NaX zeolites at 40°C support the view that Na+ cations might be considered as sites for sorption of these molecules. Force fields created by Eu4O10+ present in Eu/NaX zeolite may affect sorption. On the other hand, Brønsted acid sites in Eu/NaX enhance sorption of cyclopropane and propylene at 40°C. Chemisorption of propylene on the Brønsted acid sites of Eu/NaX is reversible and may occur via a propylene carbenium cation intermediate. Small amounts of hexene are formed during this sorption. The amount of Brønsted acid sites in the present Eu/NaX is at least 0.6 mmol/g cat. © 1992.