Crystallization of zeolite ZSM-39 studied by 13C and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy

Abstract

¹³ C CP MAS NMR, ²⁹Si MAS NMR and XRD have been used to study the crystallization of zeolite ZSM-39 in the tetramethylethylenediamine (TMEDA)–SiO₂–H₂O system. With the formation of the precursor from SiO₂ species surrounding TMEDA followed by nucleation, the ¹³C chemical shift of the —C₂H₄— group moves progressively to higher field. This indicates that one molecule of TMEDA is shared by two neighbours of the [5¹²6⁴] cage and that the —C₂H₄— group of TMEDA interacts strongly with oxygen atoms located at the 6-ring window between the two cages.