Search

Facile procedures were reported for synthesis of sizable lamellar JDF-L1 crystals. Phase transformation between ETS-10 and JDF-L1 was experimentally demonstrated founding on the role of K+, Na+ and F− ions in crystal growth. Factually, K+ ions were confirmed not to participate in the crystal growth of JDF-L1. High concentrations of only Na+ and F− ions in initial gels facilitated the formation of lamellar JDF-L1 differing from normal JDF-L1 in crystal morphology and unit-cell dimensions.

Lamellar titanosilicate JDF-L1was obtained in a F−-containing gel without using organic reactants. The lamellar JDF-L1crystals in proton-form were intercalated with an aqueous 1.6-hexanediamine solution. Distinct lattice dilations were validated featuring of c-axis direction and led to an increase of ca. 4.95 A in d001 interplanar spacing. The textural modification toward lamellar JDF-L1 crystals provided a new delaminated titanosilicate material with layered JDF-L1 structure.

Zeolites with MOR and BEA structures were treated by alkaline and acid media to regulate mesoporous structures in dimensional uniformity. The mesoporous modification approach (viz. hydrothermal alkali pre-etching, bulk alkali leaching and posterior acid extraction) was demonstrated by the introduction of uniform mesopore structures into MOR and BEA crystals. Two modified zeolites with well preserving crystallinity and substantial mesoporosity exhibited the disordered but uniform BJH pore-distribution character. The dimensionally uniformizing tendency of mesopore formation is attributed to the reinforced micropore-inducing effect due to the combination of hydrothermal alkali etching with bulk alkali leaching of enhancing mass transport. In addition to the mesopore size uniformity the mesoporosity development is more available for BEA structure than for MOR structure. Moreover, the alkaline–acid modification method proposed can facilitate the adjustment on framework Si/Al ratio towards two topological zeolites.

The hydrothermal synthesis of various mesoporous materials with mordenite (MOR) structures is performed under perturbation conditions involving varying-temperature crystallizations and the use of ternary organic templates, and at least three types of mesoporous materials are obtained from the same starting gel containing the ternary organic templates. The greater structural diversities of these materials are found to correlate remarkably with the second-staged crystallization temperature and time. Among these materials, the two mesoporous materials crystallized incompletely over low temperature periods are differently structural composites consisting of MOR crystallites within disordered mesoporous phases, whereas the mesoporous mordenite crystallized completely over relatively high temperature period possesses the intrinsic microporosity and hierarchical mesoporosity. TEM morphological investigations on the mesoporous mordenite crystals demonstrate the formation of intracrystalline mesopores. Furthermore, an entirely new approach to synthesize mesoporous MOR zeolites is proposed based on the pore-inducing role of MOR structure defects and the adequate perturbation towards synthesis conditions.

Microporous alumino-titanosilicates with JDF-L1 structure, hereby designated as Al-JDF-L1, are synthesized from Na2O–TiO2–Al2O3–SiO2–KF–H2O systems. The multiple EDX data corresponding to Al-JDF-L1 crystal compositions provide evidence for the incorporation of aluminum (III) into JDF-L1 framework tetrahedra. Pure layered Al-JDF-L1 crystals are provided at least with the atomic ratio of Al/Ti around 0.07. The Al-JDF-L1 crystals with the higher Al/Ti atomic ratio (ca. 0.37) grow as the dominant phase coupled with the less competing phase identified as hexagonal erionite. Furthermore, the isostructural analog (Al/Ti=ca. 0.35) prepared using the methyl cellulose-containing initial gel reveals the features of layered but wrinkled structures with an increased porosity.