Multinuclear high resolution solid state NMR characterization of zeolites Nu-10 and ZSM-5 synthesized in the presence of tetraethylenepentamine and diaminopropane

The synthesis of zeolite Nu-10 was investigated in the presence of alkali c hlorides and tetraethylenepentamine (TEPA) or 1,3-diaminopropane (DAP) as o rganic structure-directing agents. By means of C-13 CP MAS NMR spectroscopy it was possible to identify in eac h case the nature of the organic species occluded in the channel system of the as-synthesized zeolite. TEPA is incorporated intact in its di- or tri-p rotonated form, depending on the At content of the initial hydrogel. DAP is occluded in its mono-protonated form together with n-propylamine, di-n-pro pylamine and pyridine, these latter stemming from a prompt decomposition of DA-P during the synthesis. This decomposition can be strongly affected by the synthesis temperature; the organic intermediates so formed can readily favor the formation of other types of zeolite structures and hence complete ly re-orient the synthesis route. Structural SiO- defect groups, neutralizing the excess of positive charges, are created together with terminal SiOH groups. Their relative amounts wer e determined using chemical and thermal analysis combined with Si-29 NMR da ta. (C) 2001 Elsevier Science B.V. All rights reserved.