Effect of the compensating cation on the adsorption of t-butylchloride on zeolite Y

Abstract

Adsorption of t-butylchloride on a series of metal-exchanged Y zeolite (Na +, Ag +, Cu 2+, Fe 3+) was studied by infrared spectroscopy, at different temperatures. At 148 K, the adsorption of t-butylchloride on NaY and AgY zeolites forms isobutene as main product, characterized by a band a 1639 cm −1. Upon increasing of temperature the isobutene forms an alkoxide and oligomerizes on the zeolite surface. On CuY and FeY zeolites no significant olefinic band was observed at 148 K upon adsorption of the t-butylchloride, although bands relative to CH stretching and bending vibrations could be easily observed. Upon increasing the temperature to 298 K, both zeolites give rise to olefinic bands. The results suggest that on NaY and AgY zeolite, proton elimination is the main pathway, while on CuY and FeY, formation of an adsorbed t-butoxy group is preferential at low temperature. In all zeolites, at room temperature, oligomerization occurs. This was confirmed by co-adsorption of t-butylchloride with 2-methyl-1-butene, showing that olefin was consumed.