Effect of synthesis conditions on the properties of nanocrystalline faujasites

• Published in: Petroleum chemistry Vol. 56; no. 12; pp. 1168 - 1172
• Main Authors: Knyazeva, E. E., Yakimov, A. V., Shutkina, O. V., Konnov, S. V., Panov, A. V., Kleimenov, A. V., Kondrashev, D. O., Golovachev, V. A., Ivanova, I. I.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01.12.2016; Springer; Springer Nature B.V
• Subjects: Analysis; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Nanocrystals; Selectivity; Zeolites; phase composition; zeolite Y; pore structure; chemical composition; nanocrystals; unit cell parameter
• ISSN: 0965-5441; 1555-6239
• DOI: 10.1134/S0965544116120069

The effect of crystallization parameters on the properties of nanocrystalline zeolites Y has been studied to optimize the synthesis conditions. Zeolites Y are prepared by the three-stage hydrothermal crystallization with a gradual rise in synthesis temperature from room temperature to 60°C using the Na 2 O/SiO 2 ratio in the reaction mixture and the number and duration of individual synthesis stages as variable synthesis parameters. It has been shown that an increase in the Na 2 O/SiO 2 molar ratio in the reaction mixture above 9.6 leads to a change in the crystallization selectivity and causes formation of zeolite X with a crystal size of 200 nm as a crystalline product. An increase in the duration of the synthesis stage at 60°C is accompanied by increase in the crystal size and entails formation of an analcime impurity phase. A decrease in the duration of reaction mixture aging stages at 25 and 38°C leads to an increase in the zeolite Y nanocrystal sizes and a decrease in the crystalline product yield. It has been found that a pure zeolite Y phase with a nanocrystal size of 320–350 nm and a SiO 2 /Al 2 O 3 ratio of 3.6–4.2 is formed during the three-stage synthesis from a (7.2–9.6)Na 2 O · Al 2 O 3 · 14.4 SiO 2 · 290 H 2 O reaction mixture with a yield of 0.60–0.88 g/g of reaction mixture.