2D multiple quantum 27Al NMR and 29Si NMR characterization of levyne

Combined 1D and 2D multiple-quantum Al-27 NMR results together with Si-29 NMR data provide interesting information on the siting of Al in levyne zeolite. It is clearly shown that the distribution of Al is random in the structure, as the relative intensity of the two tetrahedral species is equal to 2, corresponding to the ratio of T-1 and T-2, the crystallographically different tetrahedral sites. The dealumination which occurs during calcination appears to be specific. Only the tetrahedral Al atoms on sites T-1 are transformed into deformed tetrahedral species and extraframework octahedral species, while the Al atoms on sites T-2 remain unchanged. (C) 1999 Elsevier Science B.V. All rights reserved.