HSIL-Based Synthesis of Ultracrystalline K,Na-JBW,a Zeolite Exhibiting Exceptional Framework Ordering and Flexibility

摘要

A reproducible synthesis strategy for ultracrystalline K,Na-aluminosilicate JBW zeolite is reported.The synthesis uses a Na-based hydrated silicate ionic liquid(HSIL) as a silicon source and gibbsite as the aluminum source.~(27)A1 and ~(23)Na NMR spectra exhibit crystalline second-order quadrupole patterns in the hydrated as well as dehydrated states and distinct resonances for different T-sites demonstrating an exceptional degree of order of the elements of the JBW framework,observed for the first time in a zeolite.Detailed structural analysis via NMR crystallography,combining powder X-ray diffraction and solid-state NMR of all elements(~(27)Al,~(29)Si,~(23)Na,~(39)K,and ~1H),reveals remarkable de-and rehydration behavior of the JBW framework,transforming from its as-made hydrated structure via a modified anhydrous state into a different rehydrated symmetry while showing astonishing flexibility for a semicondensed aluminosilicate.Its crystallinity,exceptional degree of ordering of the T atoms and sodium cations,and the fully documented structure qualify this defect-free K,Na-aluminosilicate JBW zeolite as a suitable model system for developing NMR modeling methods.