EVIDENCE FOR THE NATURE OF TRUE LEWIS SITES IN FAUJASITE-TYPE ZEOLITES

Experimental evidence was gathered for the nature of Lewis sites in copper-Y zeolites. The zeolite was subjected to several CO-O2 redox treatments. The kinetic behavior of the latter zeolite upon H2 and CO treatment was compared to that of the original sample. From this the formation of AlO+ and Cu2+-O2--Cu2+ was derived. Their existence was further confirmed using IR spectroscopy and treatment with 18O2. It is concluded that Lewis sites are not trigonal Al atoms in zeolites, but consist rather of Al-O species leached from the zeolite framework. © 1979 American Chemical Society.