Distribution of tetrahedral aluminium sites in ZSM-5 type zeolites: An Al-27 (Multiquantum) magic angle spinning NMR study

Up to now the distribution of Al atoms in the zeolite lattice could be monitored mainly by Si-29 MAS NMR. The data about the nonequivalent aluminium T sites, present in the Al-27 MAS NMR spectra, was obscured by second-order effects of quadrupolar interaction. By applying the five-quantum Al-27 MQMAS NMR method to ZSM-5 type zeolites, we were able to distinguish at least two nonequivalent aluminium T sites in the H-ZSM-5 and establish the relation between Al-27, Si-29, and H-1 NMR data. Comparison with Si-29 MAS NMR spectra gives information about the distribution and siting of aluminium in the zeolite framework.