MULTINUCLEAR MQMAS NMR-STUDY OF NH4 NA-FERRIERITES/

(MQ)MAS NMR is a powerful new method to study quadrupolar nuclei, enab ling separation of the chemical shift interaction from the qundrupolar interaction. We showed that hydrated NH4-ferrierites have two distinc t aluminum sites with an average ratio of 4:5. These sites were assign ed to T(2) + T(3) and T(5) + T(1) + T(4) sites, respectively. Upon inc rease of the aluminum content, the ratio 4:5 remained the same. At hig her Si/Al ratios, aluminum tends to form aluminum-rich zones, leaving some unit cells without aluminum atoms. Na+ exchange decreases the ave rage T-O-T angles of the aluminum sites. It has been found that Na+ io ns are preferentially located in the ''ferrierite cages'', formed at t he intersection of six-membered ring channels and eight-membered ring channels.