Solid-State NMR Evidence for the Formation of Carbocations from Propene in Acidic Zeolite-Y

摘要

In the present study we present CP-MAS NMR evidence both for dynamic and static carbocations which result from the reaction of propene in a H-Y zeolite. Previous infrared studies have shown that propene oligomerizes in acidic zeolites, even at 25 C, to form molecules containing ca. 10 methylene units. At higher temperatures (150 - 250 C) aromatics were formed on H-ZSM-5 and H-mordenite, but on H-Y zeolites only coke was observed. The UV reflectance spectra of ethene or propene adsorbed on H-ZSM-5 and H-Y zeolites indicated the formation of cyclopentenyl and allyl carbocations, respectively.