Quantitative high-resolution 27Al NMR: tetrahedral non-framework aluminium in hydrothermally treated zeolites

Studies of heterogeneous catalysis using high-resolution solid state NMR

“…In accordance with the data of [1,2,4,7,57,60,61], it follows that the treatment of NH4Y zeolite under conditions of thick or shallow bed, decreases the intensity of the line from the lattice Al, the total intensity of the spectrum remaining unchanged. The fact that the total intensity of the spectrum remains implies that all Al atoms that are present in the sample, are re- corded in NMR spectra.…”

Dealumination of HZSM-5 via steam-treatment

“…As a consequence, broadening of the contour below the isotropic line was observed. Samoson et al [7] reported similar features in spectra of dealuminated faujasites and ZSM-5 and suggested that the signal is related to non-framework tetrahedral aluminum species. The isotropic projection in the F1 dimension gives a 1D highresolution spectrum of aluminum without quadrupolar second-order broadening.…”

“…Others suggest the intermediate species being distorted tetrahedral aluminum species [7], which could, however, also be the precursors to the penta-coordinated aluminum species. It is interesting to note that also the nature of the resulting extra-framework aluminum species is not unequivocally accepted.…”

A ZSM-5-based Catalyst for Efficient Production of Light Olefins and Aromatics from Fluidized-bed Naphtha Catalytic Cracking

“…The peak with low intensity at 60 ppm is characteristic of the tetrahedral aluminum species located in the framework of zeolite ZSM-5 [13]. The peak at 38 ppm is attributed to the pentahedral or distorted tetrahedral coordinated aluminum atoms in extra-framework species [17][18][19]. The strong peak at 5 ppm is assigned to the extra-framework Al with octahedral coordination [20].…”