Differentiating the role of organic additives to assemble open framework aluminosilicates using INS spectroscopy

Nearchou, Antony; Armstrong, Jeff; Butler, Keith T.; Raithby, Paul R.; Sartbaeva, Asel

doi:10.1039/c9cp05798f

Cited by 2 publications

(3 citation statements)

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“…In zeolites RHO and ZK-5 it is seen that the occluded 18C6 species occupies the α-cage, as has been expected 33,34 but not explicitly proven. We observe that the 18C6 species is disordered in both zeolites, and hence the structure has been described as a cluster.…”

Section: Discussionmentioning

confidence: 57%

“…20,28 Although in both the 18C6 exists as a [(18C6)Na + ] macrocation, it is a true geometric template for the synthesis of EMT-type zeolites and a space-filling species in the synthesis of FAU-type zeolites. [29][30][31][32][33] This is important, as it demonstrates the integral role of 18C6 in the synthesis mechanism to differentiate between the two polymorphs. Zeolites RHO and ZK-5 (KFI) are two zeolites that can also be prepared using 18C6, 24,26 however the role, identity and location of the 18C6 species has not been determined.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 1 shows the framework structure of these two zeolites, in addition to the constituent SBUs. Both zeolites consist of α-cages in a body centred cubic arrangement and it is these α-cages that the 18C6 is believed to occupy, 33,34 however it has not been explicitly proven. Due to the lack of structural information, there is currently no understanding of how the 18C6 molecule is involved in the synthesis of these two zeolites in comparison to the FAU and EMT-type zeolites.…”

Section: Introductionmentioning

confidence: 99%

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The structure and location of 18-crown-6 ether in zeolites RHO and ZK-5

Nearchou

Dejoie

Raithby

et al. 2022

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The use of organic additives presents the greatest versatility and control of zeolite synthesis in order to prepare novel architectures for desired applications. Despite this prospect, there is little clarity of how organic additives are involved in framework assembly and the range of behaviours that are available. To address this issue, we have considered zeolites RHO and ZK-5 which can both be prepared using 18-crown-6 ether as an additive. Previously, this additive has shown to employ different structure directing behaviours to assemble a variety of zeolites. We have used high resolution powder X-ray diffraction and Rietveld refinement to determine structural models for zeolites RHO and ZK-5 with 18-crown-6 ether occluded in the framework. In doing so, we can observe the identity, location and orientation of the occluded additive and reason the structure directing behaviour in synthesis. We report that the isolated 18-crown-6 ether molecule is involved in the assembly of zeolite RHO, and for zeolite ZK-5 it is the K+ coordinated macrocation. In both cases the relevant additive is disordered in the framework, suggesting that they behave as space-filling species that stabilise the formation of the α-cage.

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Section: Discussionmentioning

confidence: 57%