Templating of high-silica zeolites by tetrahydrofuran in the Na2O – SiO2 – Al2O3 – H2O system

Abstract

The spontaneous crystallization of high-silica MOR, FER, MFI, MTN zeolites was investigated in the reactant system tetrahydrofuran (THF)–Na2O–SiO2–Al2O3–H2O in the temperature range 180–230°C. 13C CP MAS NMR spectra, TG/DTG/DTA and energy dispersive X-ray (EDX) analysis were used to characterize the molecules of THF trapped in the channels or the cages of the as-synthesized zeolites. The regular patterns and the distinct shift of the resonance peaks for THF in 13C MAS NMR spectra, and the higher temperatures for 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 discussed.