Novel low energy hydrogen–deuterium isotope breakthrough separation using a trapdoor zeolite

Physick, Andrew; Wales, Dominic J.; Owens, Simon; Shang, Jin; Webley, Paul A.; Mays, Timothy J.; Ting, Valeska P.

doi:10.1016/j.cej.2015.11.040

Cited by 34 publications

(24 citation statements)

References 38 publications

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“…The reflections of the XRD were indexed in the rhombohedral space group, 3 , which is observed in the natural chabazite form [33]. The diffractograms of KCHA, CsCHA and ZnCHA match with diffractograms reported in the literature [11,26,34]. It should be noted it is known that upon cation exchange of KCHA to form CsCHA or ZnCHA, a proportion of residual potassium remains CsCHA and…”

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confidence: 64%

“…The favoured positions of different cations in chabazite results in different properties for the different cation forms of chabazite, which makes chabazite materials attractive for several processes and applications. For example, in CsCHA, the Cs + cations can act as selective aperture 'trapdoors', which have been successfully utilised for gas and gaseous isotope separations [9][10][11]. This selective 'trapdoor' behaviour in chabazite is a potentially attractive functional attribute in a gas selective material for sensing applications.…”

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confidence: 99%

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Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Bordeneuve

Wales

Physick

et al. 2018

Microporous and Mesoporous Materials

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Synthetic K + chabazite (KCHA), Cs + chabazite (CsCHA) and Zn 2+ chabazite (ZnCHA) have been synthesized and investigated in order to relate the differences in their crystalline structures to their thermal stability, moisture content and frequency dependent alternating current (AC) conductivity, permittivity and phase angle at a range of temperatures. The materials are shown to exhibit the universal dielectric response, which is typical of materials consisting of both conductive and insulating regions. Due to the presence of porosity the three chabazites were hydrated significantly at room temperature and so the dehydrated state was achieved by heating the chabazites to high temperatures to ensure that all different energetic types of water were removed. Cation migration activation energies for KCHA (0.66 ± 0.10) eV, CsCHA (0.88 ± 0.01) eV and ZnCHA (0.90 ± 0.01) eV were determined during the cooling cycle from the fully dehydrated state to provide an accurate measurement the activation energies. Good thermal stability of the materials was observed up to 710 °C and below 200 °C the electrical properties can be strongly influenced by hydration level. Overall, it was determined that when either hydrated or dehydrated, KCHA had the highest conductivity and lowest cation migration activation energy of the three studied chabazites and thus has the most promising electrical properties for potential use as a gas sensing material in next-generation electrical-based gas sensors.

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Section: Position Of Figure 2 Position Of Caption For Figuresupporting

confidence: 64%

Section: Position Of Caption For Figure 1a and 1bmentioning

confidence: 99%

Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Bordeneuve

Wales

Physick

et al. 2018

Microporous and Mesoporous Materials

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“…4b–d ) relates to the order of the distribution width β and the molecular mass of each guest species: H 2 (30 K), CH 4 (50 K), N 2 (57 K) and Ar (118 K). This result has important implications for the potential use of temperature-regulated sieving to separate isotopes (for example, hydrogen-deuterium-tritium 44 ).…”

Section: Resultsmentioning

confidence: 99%

Temperature-regulated guest admission and release in microporous materials

Shang

et al. 2017

Nat Commun

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While it has long been known that some highly adsorbing microporous materials suddenly become inaccessible to guest molecules below certain temperatures, previous attempts to explain this phenomenon have failed. Here we show that this anomalous sorption behaviour is a temperature-regulated guest admission process, where the pore-keeping group's thermal fluctuations are influenced by interactions with guest molecules. A physical model is presented to explain the atomic-level chemistry and structure of these thermally regulated micropores, which is crucial to systematic engineering of new functional materials such as tunable molecular sieves, gated membranes and controlled-release nanocontainers. The model was validated experimentally with H2, N2, Ar and CH4 on three classes of microporous materials: trapdoor zeolites, supramolecular host calixarenes and metal-organic frameworks. We demonstrate how temperature can be exploited to achieve appreciable hydrogen and methane storage in such materials without sustained pressure. These findings also open new avenues for gas sensing and isotope separation.

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“…[3][4][5] Another motivation for studying these systems is their application in processes of reversible storage of hydrogen in porous materials, [6][7][8][9][10] where dopant metal cations act as centers to which hydrogen molecules attach and isotopic substitution effects (D 2 by H 2 ) have been found to be relevant. 11 In all these cases, it is also interesting to study the differences in the interaction depending on whether the molecule is in the ground rotational state (para-H 2 , ortho-D 2 ) or in the first rotationally excited state (ortho-H 2 , para-D 2 ), as has been found in related works. 2,12 M + -H 2 complexes where the metal is an alkaline atom have been extensively investigated, particularly those involving the lighter ions.…”

Section: Introductionmentioning

confidence: 81%

Complexes of Alkali Metal Cations and Molecular Hydrogen: Potential Energy Surfaces and Bound States

et al. 2019

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Complexes between metal cations and molecular hydrogen are systems quite amenable for precise spectroscopic and theoretical studies and, at the same time, they are relevant for applications in hydrogen storage and astrochemistry. In this work we report new intermolecular potential energy surfaces and rovibrational states calculations for complexes involving molecular hydrogen and alkaline metal cations, M +-H 2 (M + =Na + , K + , Rb + , Cs +). The intermolecular potentials, formulated in an internally consistent way to emphasize differences in the properties of the systems, are represented by simple analytical expressions whose parameters have been optimized from comparison with accurate ab initio calculations. Properties of the low-lying bound states-binding energies, frequencies, rotational constants-are compared with previous measurements or computations and an overall good agreement is achieved, supporting the reliability of the present formulation. Variations of these properties as a function of the cation size and isotopic substitution, with a proper sequence of ortho and para rotational levels, are also discussed.

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Novel low energy hydrogen–deuterium isotope breakthrough separation using a trapdoor zeolite

Cited by 34 publications

References 38 publications

Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Understanding the AC conductivity and permittivity of trapdoor chabazites for future development of next-generation gas sensors

Temperature-regulated guest admission and release in microporous materials

Complexes of Alkali Metal Cations and Molecular Hydrogen: Potential Energy Surfaces and Bound States

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