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

Combined 1D and 2D multiple-quantum Al-27 NMR results together with Si-29 N MR data provide interesting information on the siting of Al in levyne zeoli te. It is clearly shown that the distribution of Al is random in the struct ure, 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 diffe rent tetrahedral sites. The dealumination which occurs during calcination a ppears to be specific. Only the tetrahedral Al atoms on sites T-1 are trans formed into deformed tetrahedral species and extraframework octahedral spec ies, while the Al atoms on sites T-2 remain unchanged. (C) 1999 Elsevier Sc ience B.V. All rights reserved.