NUCLEAR-MAGNETIC-RESONANCE STUDIES OF THE SYNTHESIS OF SILICALITE BY THE FLUORIDE METHOD

The composition of the mother liquor in the course of synthesis of silicalite by the fluoride method has been monitored by C-13, F-19 and Si-29 NMR and by atomic absorption spectrometry. The Si content never exceeds 5% of the total Si content. Several distinct fluorosilicate species apart from SiF62- coexist in a complex dynamic equilibrium in the solution. The results indicate that synthesis proceeds via the type B solid-solid transformation mechanism, and we describe the successive reaction steps.