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  Combination of X-ray powder diffraction and adsorption calorimetry for the characterization of calcium exchanged LTA zeolites

Mauer, V., Petersen, H., Bläker, C., Pasel, C., Weidenthaler, C., & Bathen, D. (2022). Combination of X-ray powder diffraction and adsorption calorimetry for the characterization of calcium exchanged LTA zeolites. Microporous and Mesoporous Materials, 337: 111940. doi:10.1016/j.micromeso.2022.111940.

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 Creators:
Mauer, Volker1, Author
Petersen, Hilke2, Author              
Bläker, Christian1, Author
Pasel, Christoph1, Author
Weidenthaler, Claudia2, Author              
Bathen, Dieter1, 3, Author
Affiliations:
1Thermal Process Engineering, University of Duisburg-Essen, Lotharstraße 1, 47057, Duisburg, Germany, ou_persistent22              
2Research Group Weidenthaler, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1950291              
3Institute of Energy and Environmental Technology e.V. (IUTA), Bliersheimer Str. 60, 47229, Duisburg, Germany, ou_persistent22              

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Free keywords: LTA zeolite; Heat of adsorption; Crystal structure analysis; Powder diffraction; Cation site
 Abstract: While structural and chemical properties of adsorbents are largely known, energetic properties are mostly not known yet. In cation exchanged zeolites, the type, number, and position of cations have a major influence on energetic properties. Therefore, the energetic values of cations were investigated systematically on LTA zeolites. In these CaNaA materials, Na+-cations were selectively replaced by Ca2+-cations with calcium exchange rates between 8.7% and 92.1%. The cation sites were determined by crystal structure analysis of X-ray powder diffraction data (XRPD). Rietveld analysis showed the sequence of emptying Na+-cations from the various cation sites and the occupancy sequence of Ca2+-cations as a function of the exchange rate. In addition, sensor gas calorimetry was used to measure the heat of adsorption using methane as a sample molecule. The results show an increase in capacity and heat of adsorption up to an exchange rate of 68.6%. At higher exchange rates, the capacity and heat of adsorption decrease again. Characteristic plateaus of the heat of adsorption were found for all materials. By combining XRPD and calorimetry, the plateaus of the heat of adsorption were assigned to the different cation positions inside the zeolite cages and the respective energetic contributions were determined. Ca2+-cations represent energetically more valuable adsorption sites compared to Na+-cations. Furthermore, differences in the energetic values of the various cation sites were identified. It was also found, that the interactions with the zeolite framework provide the largest contribution.

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Language(s): eng - English
 Dates: 2022-02-082022-04-202022-04-272022-05-01
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1016/j.micromeso.2022.111940
 Degree: -

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Title: Microporous and Mesoporous Materials
  Abbreviation : Microporous Mesoporous Mater.
Source Genre: Journal
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Publ. Info: Amsterdam : Elsevier
Pages: - Volume / Issue: 337 Sequence Number: 111940 Start / End Page: - Identifier: ISSN: 1387-1811
CoNE: https://pure.mpg.de/cone/journals/resource/954926228401