The 27Al DOR NMR characterization of the molecular sieve AlPO4-8.

27Al double rotation (DOR) NMR spectroscopy has been applied to investigate the framework ordering in the aluminophosphate molecular sieve AlPO4-8 during the hydration process. Relative well-resolved peaks in the DOR spectra of both dehydrated and successively rehydrated AlPO4-8 allow the isotropic shifts and the quadrupolar shifts to be correlated with the local framework structure. The rather complex interaction of water with AlPO4-8 occurs in a specific way, not randomly. For dehydrated AlPO4-8 efforts are shown to correlate respectively the isotropic shifts to the mean Al-O-P angles and the quadrupolar coupling constants to the shear strains of the different aluminium sites.