Syntheses and structural properties of four Rb-aluminosilicate zeolites

Itabashi, Keiji; Ikeda, Takuji; Matsumoto, Akihiko; Kamioka, Kunikazu; Kato, Masaru; Tsutsumi, Keisuke

doi:10.1016/j.micromeso.2008.01.037

Cited by 14 publications

(8 citation statements)

References 27 publications

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“…When the Si/OH − ratio of the gel is in the range 2.5–4.0, on the other hand, zeolite L (LTL) co‐crystallized as an impurity. However, a further increase in the Si/OH − ratio to 5.0 again led to the formation of pure K‐MER with a bulk Si/Al ratio of 3.8, the highest ratio among the MER zeolites obtained under the wholly inorganic conditions so far, with the exception of RMA‐2 with Si/Al=4.2 synthesized using Rb + only as a SDA [8e] . Unfortunately, the crystallization field of this MER zeolite is very narrow: when the Si/OH − ratio of the gel was fixed to 5.0, even a small change in its Si/Al ratio yielded the formation of an unknown but probably dense material as the major or minor phase (Supporting Information, Table S1).…”

Section: Resultsmentioning

confidence: 93%

The Origin of Selective Adsorption of CO₂ on Merlinoite Zeolites

Choi,

Jo,

Min

et al. 2020

Angew Chem Int Ed

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The CO2 adsorption behavior at 25–75 °C and 0–1.0 bar of various alkali cation‐exchanged forms of merlinoite (framework type MER) zeolites with Si/Al=2.3 and 3.8 is described. The adsorption isotherms at 25 °C on the Na+, K+, Rb+, and Cs+ forms of MER zeolite with Si/Al=2.3 are characterized by a clear step, the CO2 pressure of which differs notably according to the type of their extraframework cations. Structural analysis shows that CO2 adsorption on the former three zeolites includes the relocation of gating cations with high site occupancy and the remarkable concomitant structural breathing. We define this unusual adsorption phenomenon as a cooperative cation gating‐breathing mechanism. The overall results suggest that the actual mechanism of selective CO2 adsorption on intermediate‐silica small‐pore zeolites can change from cation gating to cooperative cation gating‐breathing to breathing, depending on a combination of their topological and compositional flexibilities.

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Section: Resultsmentioning

confidence: 93%

The Origin of Selective Adsorption of CO₂ on Merlinoite Zeolites

Choi,

Jo,

Min

et al. 2020

Angew Chem Int Ed

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“…Similar to ABW, the direct synthesis of pollucite using CsOH or the (dry) transformation in CsCl is only reported at higher temperatures. 17,18 An extensive study of direct syntheses in the Rb system was done for the first time by Itabashi et al (2008). 15 They reported the synthesis of Rb-MER with a Si/Al ratio of 4 under rotation at 150 1C.…”

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confidence: 99%

Alkaline cations directing the transformation of FAU zeolites into five different framework types

et al. 2013

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“…The starting material, zeolite-W (K-MER), was synthesized under hydrothermal conditions according to Itabashi et al [ 23 ]. An amount of 50 wt % of aqueous solution of KOH (Sigma-Aldrich) and Al(OH) 3 (Sumitomo Chemical Co. Ltd., Tokyo, Japan) was mixed and heated on a hot plate to prepare a potassium aluminate solution.…”

Section: Methodsmentioning

confidence: 99%

“…We have successfully prepared zeolite-W (K-MER) and its fully exchanged monovalent cation forms (Li-, Na-, and Ag-MER) by using conventional hydrothermal synthesis, following the work of Itabashi et al, and the ion-exchange method, respectively [ 23 ]. Here, we report comparative and systematic changes in crystal structures and chemical composition of a monovalent M-MER series at ambient conditions using high-resolution synchrotron X-ray powder diffraction, Rietveld structure refinement, energy dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis (TGA).…”

Section: Introductionmentioning

confidence: 99%

Structural Characterization and Comparison of Monovalent Cation-Exchanged Zeolite-W

Seoung

Kim

et al. 2020

Materials

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We report comparative structural changes of potassium-contained zeolite-W (K-MER, structural analogue of natural zeolite merlinoite) and monovalent extra-framework cation (EFC)-exchanged M-MERs (M = Li+, Na+, Ag+, and Rb+). High-resolution synchrotron X-ray powder diffraction study precisely determines that crystal symmetry of MERs is tetragonal (I4/mmm). Rietveld refinement results reveal that frameworks of all MERs are geometrically composed of disordered Al/Si tetrahedra, bridged by linkage oxygen atoms. We observe a structural relationship between a group of Li-, Na-, and Ag-MER and the group of K- and Rb-MER by EFC radius and position of M(1) site inside double 8-membered ring unit (d8r). In the former group, a-axes decrease reciprocally, c-axes gradually extend by EFC size, and M(1) cations are located at the middle of the d8r. In the latter group, a- and c-axes lengths become longer and shorter, respectively, than axes of the former group, and these axial changes come from middle-to-edge migration of M(1) cations inside the d8r channel. Unit cell volumes of the Na-, Ag-, and K-MER are ca. 2005 Å3, and the volume expansion in the MER series is limited by EFC size, the number of water molecules, and the distribution of extra-framework species inside the MER channel. EFC sites of M(1) and M(2) show disordered and ordered distribution in the former group, and all EFC sites change to disordered distribution after migration of the M(1) site in the latter group. The amount of water molecules and porosities are inversely proportional to EFC size due to the limitation of volume expansion of MERs. The channel opening area of a pau composite building unit and the amount of water molecules are universally related as a function of cation size because water molecules are mainly distributed inside a pau channel.

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Syntheses and structural properties of four Rb-aluminosilicate zeolites

Cited by 14 publications

References 27 publications

The Origin of Selective Adsorption of CO₂ on Merlinoite Zeolites

The Origin of Selective Adsorption of CO₂ on Merlinoite Zeolites

Alkaline cations directing the transformation of FAU zeolites into five different framework types

Structural Characterization and Comparison of Monovalent Cation-Exchanged Zeolite-W

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Syntheses and structural properties of four Rb-aluminosilicate zeolites

Cited by 14 publications

References 27 publications

The Origin of Selective Adsorption of CO2 on Merlinoite Zeolites

The Origin of Selective Adsorption of CO2 on Merlinoite Zeolites

Alkaline cations directing the transformation of FAU zeolites into five different framework types

Structural Characterization and Comparison of Monovalent Cation-Exchanged Zeolite-W

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The Origin of Selective Adsorption of CO₂ on Merlinoite Zeolites

The Origin of Selective Adsorption of CO₂ on Merlinoite Zeolites