NMR investigation of substituted aluminophosphate AEL, ATS, ATN, AFS, AFY and GIS molecular sieves

Abstract

The novel metal-incorporated aluminophosphates MAPO-11, MAPO-36, MAPSO-36, CoAPO-36, ZAPO-36, MAPO-39, MAPO-43 and MAPO-50 have been prepared and studied by ²⁷ Al and ³¹ P MAS NMR spectroscopy. ²⁷ Al NMR spectra show a signal characteristic of tetrahedral Al in the range 30–45 ppm. MeAPOs (Me = metal) with higher metal loadings also show additional signals at lower chemical shift due to Al in higher coordination. ³¹ P NMR spectra show complex patterns of overlapping signals which can be assigned to P atoms having differing numbers of Al or metal atom next-nearest neighbours. The P/Al and P/Me ratios calculated from the relative intensities of these signals are in good agreement with the results of chemical analysis. The intensity ratios do not, however, follow a binomial distribution indicating non-random patterns of metal substitution in the AlPO frameworks. The effects of calcination of these materials are also described.