Steric Effects in Nitrogen Adsorption by Mordenite

Hayhurst, David T.; Sefcik,

doi:10.1021/bk-1983-0218.ch020

Cited by 4 publications

(2 citation statements)

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“…This effectively isolates the main channels from one another and leaves each main channel lined with two rows of side pockets. It is reported 52 that molecules as large as argon can access to these pockets. The remaining four sodium ions are reported 53 to occupy random sites of the 8-ring and 12ring positions in the main channel of the zeolite.…”

Section: Discussionmentioning

confidence: 99%

Sorption of Nitrogen, Oxygen, and Argon in Silver-Exchanged Zeolites

Sebastian

Jasra

2005

Ind. Eng. Chem. Res.

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Sorption of nitrogen, oxygen, and argon on silver-exchanged zeolites, A, X, Y, mordenite, BEA, L, and ZSM-5 at 288.2 and 303.0 K were studied. The nitrogen adsorption capacity, selectivity, and heat of adsorption in the low-pressure region are very high for silver-exchanged zeolites compared to other cation-exchanged samples, showing strong interactions between nitrogen molecules with the silver cations. Heat of nitrogen adsorption decreases with the increase in the adsorption equilibrium pressure in all zeolites except zeolite A. However, zeolite AgA shows N2 adsorption capacity of 20.8 molecules per unit cell for nitrogen at 101.3 kPa and N2/O2 selectivity in the range of 5−14.6 at 303 K, the highest known so far for any zeolite A type of adsorbent. Other zeolites also show increased adsorption capacities for nitrogen on silver exchange, but these are smaller compared to those observed for zeolite A. Furthermore, unlike other cation-exchanged zeolites which show small oxygen selectivity over argon, silver-exchanged zeolites display argon selectivity over oxygen. The stronger interaction of nitrogen molecules with silver cations present inside zeolite cavities is attributed to π-complexation of N2 molecules with silver cations. Selective adsorption of argon is explained in terms of its interaction with silver cations through Ar(pσ)−Ag(dσ) bonding molecular orbital.

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Section: Discussionmentioning

confidence: 99%

Sorption of Nitrogen, Oxygen, and Argon in Silver-Exchanged Zeolites

Sebastian

Jasra

2005

Ind. Eng. Chem. Res.

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“…As a matter of fact this time for N 2 in NaA is very long at 193 K; it is then difficult to perform isotherms at lower temperatures because of the temperature regulation. At 78 K, the diffusivity of N 2 in NaA is completely hindered, meanwhile O 2 continues to diffuse easily in this zeolite; the Na cations in the window aperture impede totally the intracrystalline diffusion of N 2 . − This fact has been used to verify the quantity which can be condensed in the intergrain volume.…”

Section: Methodsmentioning

confidence: 99%

Molecular Interactions in Nanoporous Adsorbents. Adsorption of N₂ and O₂ in Zeolites with Cavities or Channels: Na₁₂A, Ca₆A, NaX, and Decationated Mordenite

1996

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The adsorption of two small molecules in porous crystals presenting void volumes of different shapes (cavities of ∼12 Å diameter, channels of ∼6 Å diameter) is measured in a large range of temperatures and pressures. The data analysis shows off the difference in the intermolecular forces between N2 and O2 molecules; in condensed phases the molecule-molecule interaction is repulsive and it is more repulsive for N2. The density of the adsorbed phase is compared with that of the liquid at three temperatures; that points out the confinement effect which is dominant in the channels.

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Zur Wechselwirkung von Stickstoff und Sauerstoff mit Adsorptionszentren in Zeolithen

Oehme

Meiler

Lochmann

et al. 1987

Zeitschrift fuer Chemie

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By use of adsorption measurements and 15N nmr studies could be shown that the adsorption of nitrogen in zeolites of type A and X is strongly influenced by the cations. The interaction increases in the sequence Na+ < Ca2+ < Mg2+. Whereas the interaction with Na+ and Mg2+ leads to chemical shifts of −2,5 and −9,5 ppm, respectively, the adsorption of nitrogen in a cation free zeolite shows no influence on the chemical shift with reference to free gas. Ab initio and semiempirical calculations support the results of the experiments. By extention of these calculations to oxygen the preference of nitrogen could be proved.

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Steric Effects in Nitrogen Adsorption by Mordenite

Cited by 4 publications

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Sorption of Nitrogen, Oxygen, and Argon in Silver-Exchanged Zeolites

Sorption of Nitrogen, Oxygen, and Argon in Silver-Exchanged Zeolites

Molecular Interactions in Nanoporous Adsorbents. Adsorption of N₂ and O₂ in Zeolites with Cavities or Channels: Na₁₂A, Ca₆A, NaX, and Decationated Mordenite

Zur Wechselwirkung von Stickstoff und Sauerstoff mit Adsorptionszentren in Zeolithen

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Steric Effects in Nitrogen Adsorption by Mordenite

Cited by 4 publications

References 0 publications

Sorption of Nitrogen, Oxygen, and Argon in Silver-Exchanged Zeolites

Sorption of Nitrogen, Oxygen, and Argon in Silver-Exchanged Zeolites

Molecular Interactions in Nanoporous Adsorbents. Adsorption of N2 and O2 in Zeolites with Cavities or Channels: Na12A, Ca6A, NaX, and Decationated Mordenite

Zur Wechselwirkung von Stickstoff und Sauerstoff mit Adsorptionszentren in Zeolithen

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Molecular Interactions in Nanoporous Adsorbents. Adsorption of N₂ and O₂ in Zeolites with Cavities or Channels: Na₁₂A, Ca₆A, NaX, and Decationated Mordenite