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. P-31 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. Al-27 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. Al-27 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 Al-27-P-31 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 Al-27 and F-19 MAS along with F-19, Al-27 and Al-27 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. C-13 NMR of as-synthesized EMM-8 (AlPO and SAPO) shows that the dimethylamino pyridine structure-directing agent remains intact. Si-29 and H-1 NMR indicate non-uniform incorporation of Si into SAPO EMM-8. (C) 2007 Elsevier Inc. All rights reserved.