Pressure-induced hydration and cation migration in a Cs+ exchanged gallosilicate zeolite LTL: Synchrotron X-ray powder diffraction study at ambient and high pressures

Seoung, Donghoon; Lee, Yong Jae; Lee, Hyun Hwi; Ahn, Docheon; Shin, Nam Soo; Vogt, Thomas

doi:10.1016/j.micromeso.2010.07.023

Cited by 12 publications

(7 citation statements)

References 26 publications

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“…Several zeolites were amorphized under high pressure, i.e., pressure-induced full or partial amorphization reverting back to the original crystalline structure upon decompression [15,16]. The partly disordered structure resulted from the local collapse and distortion of zeolite framework, which 4 was closely related to the properties of charge-balancing cations in the zeolites [17]. Lee et al reported that high pressure of 1.9 GPa led to the irreversible migration and rearrangement of charge-balancing cations, i.e., pressure-induced migration, and to the formation of super-hydrated zeolite with a doubled water content described as pressure-induced hydration [18].…”

Section: Introductionmentioning

confidence: 99%

Mechanical pressure-mediated Pd active sites formation in NaY zeolite catalysts for indirect oxidative carbonylation of methanol to dimethyl carbonate

Wang

Liu

et al. 2021

Journal of Catalysis

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Section: Introductionmentioning

confidence: 99%

Mechanical pressure-mediated Pd active sites formation in NaY zeolite catalysts for indirect oxidative carbonylation of methanol to dimethyl carbonate

Wang

Liu

et al. 2021

Journal of Catalysis

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“…Experimentally, framework flexibility can be probed by applying external pressure and studying the response of the structure. The mechanical behaviour of zeolites can be strongly influenced by the extra-framework content, such as occluded structure-directing cations [7,22,23,24] and organic additives [25], and connections between framework flexibility and guest structure-directing species can in principle provide valuable insights into the nature of the TO 4 clathration process during crystallisation.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic Flexibility of the EMT Zeolite Framework under Pressure

et al. 2019

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The roles of organic additives in the assembly and crystallisation of zeolites are still not fully understood. This is important when attempting to prepare novel frameworks to produce new zeolites. We consider 18-crown-6 ether (18C6) as an additive, which has previously been shown to differentiate between the zeolite EMC-2 (EMT) and faujasite (FAU) frameworks. However, it is unclear whether this distinction is dictated by influences on the metastable free-energy landscape or geometric templating. Using high-pressure synchrotron X-ray diffraction, we have observed that the presence of 18C6 does not impact the EMT framework flexibility—agreeing with our previous geometric simulations and suggesting that 18C6 does not behave as a geometric template. This was further studied by computational modelling using solid-state density-functional theory and lattice dynamics calculations. It is shown that the lattice energy of FAU is lower than EMT, but is strongly impacted by the presence of solvent/guest molecules in the framework. Furthermore, the EMT topology possesses a greater vibrational entropy and is stabilised by free energy at a finite temperature. Overall, these findings demonstrate that the role of the 18C6 additive is to influence the free energy of crystallisation to assemble the EMT framework as opposed to FAU.

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“…[24] Our refinement models show that site C is susceptible to exchange with Cs + ions and is similarly populated to its gallosilicate analogue, reported by Seoung et al, to have a 50:50 fractional occupancy at this same site. [25] It is also important to note that the overall occupancy at site C by K + and Cs + ions combined is 0.83 per unit-cell compared to the full occupancy by K + ions in the parent K-L zeolite. To render an overall neutral structure, this is compensated for by the increased overall occupancy at site D which is 0.72 Cs + per unit-cell compared to the 0.63 K + in the parent K-L zeolite.…”

Section: Resultsmentioning

confidence: 99%

The Effect of Cation Exchange on the Pore Geometry of Zeolite L

Price,

Jones,

Nearchou

et al. 2022

Preprint

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Zeolites with the LTL framework topology are attractive materials for use in optoelectronics, gas adsorption and as chemical reactors. This is due to their unique, one-dimensional (1D) channel systems which are large enough to act as hosts for organic dye molecules and other guest materials. Here, we use high-resolution X-ray diffraction to show the effect of cation exchange on the pore geometry of LTL-type zeolites. The nature of the exchanging cation is shown to influence the free access diameter, volume and water content of the 12-ring (12R) channel systems. As such, cation exchange can be used to tune the molecular sieving and adsorption properties of LTL-type zeolites. This offers new possibilities for these materials in technologically relevant applications.

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Pressure-induced hydration and cation migration in a Cs+ exchanged gallosilicate zeolite LTL: Synchrotron X-ray powder diffraction study at ambient and high pressures

Cited by 12 publications

References 26 publications

Mechanical pressure-mediated Pd active sites formation in NaY zeolite catalysts for indirect oxidative carbonylation of methanol to dimethyl carbonate

Mechanical pressure-mediated Pd active sites formation in NaY zeolite catalysts for indirect oxidative carbonylation of methanol to dimethyl carbonate

Intrinsic Flexibility of the EMT Zeolite Framework under Pressure

The Effect of Cation Exchange on the Pore Geometry of Zeolite L

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