Synthesis and characterization of Al,B-levyne type crystals from gels containing methyl-quinuclidinium ions

• Published in: Microporous and mesoporous materials 2004-06, Vol.71 (1), p.39-49
• Main Authors: De Luca, P., Violante, D., Vuono, D., Catanzaro, L., B.Nagy, J., Nastro, A.
• Format: Article
• Language: English
• Subjects: B-levyne; Chemistry; Exact sciences and technology; General and physical chemistry; Ion-exchange; Isomorphous substitution; Levyne; Methyl-quinuclidinium; Surface physical chemistry; Zeolites: preparations and properties
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/j.micromeso.2004.03.010

Al,B-, Al- and B-LZ132-levyne zeolites were obtained from gels of composition 4.5Na 2O–6MeQI– xB 2O 3–30SiO 2– yAl 2O 3–500H 2O at 170 and 190 °C with 0⩽ x⩽1 and x=7.5; 10; 15; and 20; and 0⩽ y⩽1.0, MeQ=methylquinuclidinium ion. The kinetic study shows that the induction time and the crystallization rate both decrease with increasing boron content. The boron atoms occupy framework tetrahedral positions in the Al,B-LZ132 samples, while they are at both framework tetrahedral (≈50%) and extra framework trigonal positions in B-LZ132 samples. Aluminum is incorporated in the framework at tetrahedral positions (90%) in ca. all samples. The 29Si-NMR spectra of B-LZ132 samples show that the levyne structure contains two crystallographycally different tetrahedral sites, T1 and T2, the experimental ratio varies between 1.8 and 2.0. It is shown that the presence of boron slows down the crystallization rate.