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Spatial Ordering of Organic and Inorganic Charge Centers in As-Made High-Silica Zeolites Determined by Multidimensional {1H} → 2H CPMAS NMR Correlation Spectroscopy

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journal contribution
posted on 1998-11-13, 00:00 authored by Daniel F. Shantz, Raul F. Lobo
Evidence is presented for the spatial ordering of the organic and inorganic charge centers in the as-made tectosilicates nonasil, SSZ-23, and ZSM-12. This result is based on two-dimensional 2H−{1H} NMR correlation spectroscopy experiments, which show correlation between the silanol protons of the defect site and the N-methyl groups of the structure-directing agent. The two-dimensional NMR spectra for all samples suggest that the deuterons of the methyl groups adjacent to the organic charge center are preferentially ordered relative to the defect site. Experiments performed on a sample synthesized in D2O are consistent with the interpretation of the two-dimensional NMR experiments. The results also suggest that Coloumbic organic−inorganic forces influence the location of the charge-compensating defect site in all-silica zeolites. Moreover, we suggest an additional role for certain cationic structure-directing agents in zeolite synthesis, controlling the location of T+3 atoms in the zeolite framework.