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Title: On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption

Abstract

The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites were correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibited high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (ca. 49 kJ mol-1). Mg2+ was located at the center of the zeolite hexagonal prism with the cation inaccessible to CO2, leading to a much lower Qst (ca. 30 kJ mol-1) and lower overall uptake capacity. Multiple CO2 adsorption sites were identified at a given CO2 loading amount for all four cation-exchanged ZK-5 adsorbents. Site A at the flat eight-membered ring windows and site B/B* in the γ-cages were the primary adsorption sites in Li- and Na-ZK-5 zeolites. Relatively strong dual-cation adsorption sites contributed significantly to an enhanced electrostatic interaction for CO2 in all ZK-5 samples. This interaction gives rise to a migration of Li+ and Mg2+ cations from their original locations at the center of the hexagonal prisms toward the α-cages, in which they interact more strongly with the adsorbed CO2.

Authors:
 [1];  [2];  [3];  [1]
  1. Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA
  2. Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA
  3. Department of Chemical and Biomolecular Engineering, University of Delaware, Newark Delaware 19716 USA; Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg Maryland 20899 USA
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
OSTI Identifier:
1347013
Resource Type:
Journal Article
Journal Name:
ChemSusChem
Additional Journal Information:
Journal Volume: 10; Journal Issue: 5; Journal ID: ISSN 1864-5631
Publisher:
ChemPubSoc Europe
Country of Publication:
United States
Language:
ENGLISH
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Pham, Trong D., Hudson, Matthew R., Brown, Craig M., and Lobo, Raul F. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption. United States: N. p., 2017. Web. doi:10.1002/cssc.201601648.
Pham, Trong D., Hudson, Matthew R., Brown, Craig M., & Lobo, Raul F. On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption. United States. https://doi.org/10.1002/cssc.201601648
Pham, Trong D., Hudson, Matthew R., Brown, Craig M., and Lobo, Raul F. 2017. "On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption". United States. https://doi.org/10.1002/cssc.201601648.
@article{osti_1347013,
title = {On the Structure-Property Relationships of Cation-Exchanged ZK-5 Zeolites for CO 2 Adsorption},
author = {Pham, Trong D. and Hudson, Matthew R. and Brown, Craig M. and Lobo, Raul F.},
abstractNote = {The CO2 adsorption properties of cation-exchanged Li-, Na-, K-, and Mg-ZK-5 zeolites were correlated to the molecular structures determined by Rietveld refinements of synchrotron powder X-ray diffraction patterns. Li-, K-, and Na-ZK-5 all exhibited high isosteric heats of adsorption (Qst) at low CO2 coverage, with Na-ZK-5 having the highest Qst (ca. 49 kJ mol-1). Mg2+ was located at the center of the zeolite hexagonal prism with the cation inaccessible to CO2, leading to a much lower Qst (ca. 30 kJ mol-1) and lower overall uptake capacity. Multiple CO2 adsorption sites were identified at a given CO2 loading amount for all four cation-exchanged ZK-5 adsorbents. Site A at the flat eight-membered ring windows and site B/B* in the γ-cages were the primary adsorption sites in Li- and Na-ZK-5 zeolites. Relatively strong dual-cation adsorption sites contributed significantly to an enhanced electrostatic interaction for CO2 in all ZK-5 samples. This interaction gives rise to a migration of Li+ and Mg2+ cations from their original locations at the center of the hexagonal prisms toward the α-cages, in which they interact more strongly with the adsorbed CO2.},
doi = {10.1002/cssc.201601648},
url = {https://www.osti.gov/biblio/1347013}, journal = {ChemSusChem},
issn = {1864-5631},
number = 5,
volume = 10,
place = {United States},
year = {Thu Feb 16 00:00:00 EST 2017},
month = {Thu Feb 16 00:00:00 EST 2017}
}