Abstract
Owing to the significant difference in the numbers of simulated and experimentally feasible zeolite structures, several alternative strategies have been developed for zeolite synthesis. Despite their rationality and originality, most of these techniques are based on trial-and-error, which makes it difficult to predict the structure of new materials. Assembly-Disassembly-Organization-Reassembly (ADOR) method overcoming this limitation was successfully applied to a limited number of structures with relatively stable crystalline layers (UTL, UOV, *CTH). Here, we report a straightforward, vapour-phase-transport strategy for the transformation of IWW zeolite with low-density silica layers connected by labile Ge-rich units into material with new topology. In situ XRD and XANES studies on the mechanism of IWW rearrangement reveal an unusual structural distortion-reconstruction of the framework throughout the process. Therefore, our findings provide a step forward towards engineering nanoporous materials and increasing the number of zeolites available for future applications.
Highlights
Owing to the significant difference in the numbers of simulated and experimentally feasible zeolite structures, several alternative strategies have been developed for zeolite synthesis
Such discrepancy between the numbers of proposed zeolite topologies and those produced via traditional hydrothermal approaches has prompted the development of alternative strategies for zeolite synthesis
ADOR is a unique approach because the topology of new zeolites can be predicted based on the knowledge of the parent structure
Summary
Volatile germanium chloride (bpGeCl4 = 359 K, for pure GeCl4 pGeCl4 = 94 mm Hg at 300 K19) resulting from this interaction is adsorbed/dissolved and hydrolysed in the water solution (GeCl4 + nH2O → Ge(OH)nCl4-n + nHCl), at the bottom of reactor Such an approach allows unrestricted mass transport of the species formed by destruction of the most labile Ge-rich connecting units but avoids the deep reconstruction of the germanosilicate framework mediated by water. The building units formed through VPT rearrangement depend on the structure of initial zeolite: the presence of pores in the layers of UOV and IWW zeolites results in facilitated mass transport and in the formation of S4R (for IWW) or O-bridge (for UOV) units, whereas treatment of UTL with non-porous layers produces material with alternating D4R/S4R units, under the same conditions.
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