The study of the mechanism of formation of three-membered ring containing zeolite, RUB-17 (RSN)

The synthesis of zeolites with large pore volume and extra-large pores is one of the hottest topics in zeolite science. It was shown that there is a linear correlation between the zeolite framework density and the size of building units, as the smallest rings in the frameworks (3- and 4-membered) provide the most open structures. Hence, the classical Si and Al in zeolite frameworks have been substituted with cations that offer higher flexibility of T–O–T angle and thus shift the equilibrium to smaller building units. The present study reports on the formation processes of a zincosilicate zeolite RUB-17 (framework type RSN) which contains three-membered rings. RUB-17 was synthesized from a reaction mixture having following chemical composition: 1 TEOS × 0.1 ZnO × 0.5 NaOH × 0.5 KOH × 0.08 TEAOH × 44 H2O at 180 °C. The crystal growth kinetics was studied as the reaction was monitored by powder X-ray diffraction analysis complemented by Raman spectroscopy and NMR studies. The combination of complementary methods allowed to follow the formation of 3MR. TG/DSC, N2 adsorption and chemical analysis have also been used to study the intermediates formed in the course of the crystallization process. The obtained data provided a new insight on the mechanism of formation of 3MR, as well as, zinc containing zeolites.