Multinuclear and multidimensional solid-state NMR characterization of EMM-8

The characterization of the AlPO and SAPO forms of EMM-8 with multifield, multinuclear, and multidimensional solid-state NMR techniques is essential to developing a detailed understanding of local and topological structure upon calcination, hydration, and subsequent dehydration. 31P MAS NMR shows there are at least three distinct environments for the P atoms in the as-synthesized AlPO EMM-8 in a ratio of 2:1:1 and two in a ratio of 1:1 in the calcined material. 27Al MAS NMR shows tetrahedral and penta-coordinated Al in the as-synthesized AlPO EMM-8 in the ratio of 1:1 and only Td Al in the calcined material. 27Al 3QMAS NMR shows higher resolution revealing the presence of at least two types of Td and penta Al in the as-synthesized and two distinct Td species in the calcined forms of both the AlPO and SAPO forms of EMM-8. MQMAS-selected 27Al–31P heteronuclear correlation experiments map the Al–P connectivities and indicate multiple P species that are consistent with the proposed structure of EMM-8. The AlPO EMM-8 was made with fluoride in the gel and the combination of 27Al and 19F MAS along with 19F → 27Al and 27Al → 19F CPMAS data show that the F is only coordinated with the penta-coordinated Al. The removal of F upon calcination results in a completely tetrahedral framework and only Td Al are observed. 13C NMR of as-synthesized EMM-8 (AlPO and SAPO) shows that the dimethylamino pyridine structure-directing agent remains intact. 29Si and 1H NMR indicate non-uniform incorporation of Si into SAPO EMM-8.