Xe-129 NMR studies on LaNaY zeolites with various lanthanum contents

The location of cations in LaNaY zeolites with various lanthanum contents (from 1.5 to 18.7 La ions/u. c.) has been studied by Xe-129 NMR technique. It is found that all LaNaY samples pretreated at 350 degrees C in vacuum, even with low lanthanum content, have some lanthanum cations remaining in supercages, and the amount of cations in supercages depends on the total content of lanthanum in zeolites, When the lanthanum content exceeds 8 La ions/u. c., couples of lanthanum cations appear in sodalites (beta cages), and irreversibly form bridging lanthanum oxide or oxyhydroxide species at temperature 350 degrees C, but below this content, the reaction doesn't occur, and lanthanum cations located in different sodalites, respectively, Usually, Na+ cations in Y zeolite as a whole are considered as being independent of the chemical shift of Xe atoms, but according to our result of Xe-129 NMR, the unlocated Na+ cations in supercage have an interaction with Xe and affect the chemical shift of xenon.