The spontaneous crystallization of high-silica MOR, FER, MFI, MTN zeolites
was investigated in the reactant system tetrahydrofuran (THF)-Na2O-SiO2-Al2
O3-H2O in the temperature range 180-230 degreesC. C-13 CP MAS NMR spectra,
TG/DTG/DTA and energy dispersive X-ray (EDX) analysis were used to characte
rize the molecules of THF trapped in the channels or the cages of the as-sy
nthesized zeolites. The regular patterns and the distinct shift of the reso
nance peaks for THF in C-13 MAS NMR spectra, and the higher temperatures fo
r THF escaping from the as-synthesized zeolites confirm that THF interacts
strongly with the framework of the zeolites, playing the role of a template
. The mechanism of the interaction between the framework and THF is also di
scussed.