Crystal structure of NH4-substituted chabazite

Seretkin, Yu. V.; Bakakin, V. V.; Belitzkii, I. A.

doi:10.1007/s10947-006-0184-0

Cited by 7 publications

(3 citation statements)

References 6 publications

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“…Also, the previous studies showed that the properties of analcime can be modified using lithium, zinc, and NH 4 + . [10][11][12][13][14] We recently reported the preparation of Al-rich analcime (ANA) with Si/Al ratios of 10-19. [15][16][17] This paper aims to study the structural consequences following the incorporation of Fe +3 and Ni +2 into ANA and attempts to experimentally increase its content to arrive at uniform Fe-Al ANA and Ni-Al ANA.…”

Section: Introductionmentioning

confidence: 99%

Isomorphous Substitution of Iron and Nickel into Analcime Zeolite

Azizi

Yousefpour

2011

Zeitschrift anorg allge chemie

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Studies on the effects of iron and nickel incorporation into the hydrothermal synthesis of ANA zeolite were carried out. The presented work reveals that pure Fe-Al analcime is synthesized by using starting composition with a higher iron(III) content than reported in previous publications. Furthermore, the iron(III) and nickel(II) contents play important roles in the framework of the synthesized zeolite. 759XRD, FT-IR spectroscopy, diffuse reflectance UV/Vis spectroscopy, nitrogen adsorption and SEM were used to characterize the synthesized zeolites. These investigations showed that loading of iron and nickel ions in ANA zeolite changes the pore size and morphology of analcime zeolite.

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Section: Introductionmentioning

confidence: 99%

Isomorphous Substitution of Iron and Nickel into Analcime Zeolite

Azizi

Yousefpour

2011

Zeitschrift anorg allge chemie

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“…Passaglia gave a thorough description of the chemical variability of natural chabazites and of the relations between chemical composition and physical properties . Since the pioneering works of Ames, , a series of cation-exchange experiments (Na, K, Ag, Cs, Ca, Sr, Ba, Cd, Mn, Co, Cu, NH 4 + ) were carried out. − Accurate determinations of the positions of extraframework cations and water molecules in the crystal structure of natural and cation-exchanged hydrated chabazites at room temperature have been given by Alberti et al and Calligaris et al…”

Section: Introductionmentioning

confidence: 99%

Hydration/Dehydration and Cation Migration Processes at High Temperature in Zeolite Chabazite

2008

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High temperature structural behavior of a natural chabazite of composition (Ca 1.1 Na 0.4 K 0.7 )-[Si 8.6 Al 3.4 O 24 ] • 14.4H 2 O has been characterized by means of in situ HT single-crystal X-ray diffraction (SC-XRD) and thermogravimetric analysis. Lattice dimensions have been measured in the 25-700 °C range and crystal structure refined from XRD data collected at T ) 25, 100, 125, 175, 250, 300, 425, and 600 °C. Variations of unit-cell parameters as a function of temperature reveal two discontinuities at 100 and 200 °C, to which no symmetry changes are associated, and an overall volume reduction of 2.8%. Between 200 and 250 °C, a steep contraction of cell volume is associated with a significant broadening of diffraction profiles, which turn sharp and narrow at higher temperatures. As the dehydration process proceeds with increasing T, cationic sites partly coordinated by extraframework water molecules become unstable and cations migrate toward new positions. Cations occupying the C2, C3, and C4 sites at room temperature move first toward C2 while T is raised to 200 °C, and for T > 200 °C they start migrating toward smaller cavities where coordination is assured by oxygen atoms of the framework only, the sixmembered double ring (C1 site), and a peripheral position within the eight-membered ring. The latter position has been labeled as C5. Sites C1 and C5 are stable up to 700 °C. Reversal experiments demonstrated that the whole process is reversible under the conditions of this study; by decreasing temperature, water enters the structure again and cations migrate back to their original positions.

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“…In spatial structure of chabazite, the majority NH 4 + ions are concentrated in the center of the 8‐ring . The distribution reduces the interference of Si, Al, and O atoms in chabazite framework, and creates enough space for NH 4 + ions to produce larger ionization which can affect the inducing force between cations and gas molecules . Because NH 4 + is polyatomic functional group cation with large ion radius, more significant positive and negative charge center shift occurs when inductive effect is generated between the adsorbed gas molecules and NH 4 + .…”

Section: Introductionmentioning

confidence: 99%

Study on Adsorption Properties of Ammonium Exchanged Chabazite for CO₂

Che

Song

et al. 2019

Zeitschrift anorg allge chemie

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Ammonium type chabazite (NH4CHA) and magnesium type chabazite (MgCHA) was prepared by hydrothermal synthesis and hydrothermal ion exchange. The structure and morphology of ion‐exchanged chabazite was characterized with various experimental techniques such as XRD, SEM, and ICP. The gas adsorption amount of chabazite decreases gradually with increase in temperature or decrease in pressure. The adsorption capacity of NH4CHA to CO2 was 3.33 mmol·g–1 at 273 K, and the saturated adsorption capacity of NH4CHA reached 3.88 mmol·g–1 under extreme pressure. The CO2 molecule was more likely to be adsorbed by all chabazite samples than the N2 molecule due to its linear molecular structure and greater molecular polarity. NH4CHA exhibited larger CO2/N2 selectivity, which first increased and then declined with the temperature decreasing, and reached the maximum value between 400 K to 450 K.

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Crystal structure of NH4-substituted chabazite

Cited by 7 publications

References 6 publications

Isomorphous Substitution of Iron and Nickel into Analcime Zeolite

Isomorphous Substitution of Iron and Nickel into Analcime Zeolite

Hydration/Dehydration and Cation Migration Processes at High Temperature in Zeolite Chabazite

Study on Adsorption Properties of Ammonium Exchanged Chabazite for CO₂

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Crystal structure of NH4-substituted chabazite

Cited by 7 publications

References 6 publications

Isomorphous Substitution of Iron and Nickel into Analcime Zeolite

Isomorphous Substitution of Iron and Nickel into Analcime Zeolite

Hydration/Dehydration and Cation Migration Processes at High Temperature in Zeolite Chabazite

Study on Adsorption Properties of Ammonium Exchanged Chabazite for CO2

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Study on Adsorption Properties of Ammonium Exchanged Chabazite for CO₂