Determination of the AlT1/AlT2 Ratio in MAZ Zeolites Using Line Shapes of MQ MAS NMR

Abstract

The MQ MAS NMR is used to evaluate the real, individual line shape of the Al signals in the 1D 27Al MAS NMR spectrum of zeolite materials. By the application of these real line shapes, an improved deconvolution of the 1D MAS NMR spectrum is achieved. This methodology was applied to the two tetrahedrally coordinated Al sites in mazzite zeolite, resulting in an accurate determination of the AlT1/AlT2 ratio. The method proposed here yields significant higher AlT1/AlT2 ratios then those obtained from the classical deconvolution of the 1D 27Al MAS NMR by two Lorentzian shaped lines. This implies an enrichment of Al in the 12-membered channel compared to the ratio proposed earlier in the literature.