Structural changes of synthetic paulingite (Na,H-ECR-18) upon dehydration and CO2 adsorption
SCIE
SCOPUS
- Title
- Structural changes of synthetic paulingite (Na,H-ECR-18) upon dehydration and CO2 adsorption
- Authors
- Greenaway, AG; Shin, J; Cox, PA; Shiko, E; Thompson, SP; Br; ani, S; Hong, SB; Wright, PA
- Date Issued
- 2015-04
- Publisher
- WALTER DE GRUYTER GMBH
- Abstract
- The structure of dehydrated calcined ECR-18, synthetic paulingite, topology type PAU, unit cell composition Na132H28Si512Al160O1344, has been determined by Rietveld refinement against synchrotron X-ray powder diffraction data. Upon dehydration the symmetry of Na, H-ECR-18 changes from Im (3) over barm to I (4) over bar 3m, with a corresponding decrease of cubic unit cell a parameter from 34.89412(1) angstrom to 33.3488(3) angstrom. This occurs as the framework distorts to afford closer coordination of Na+ cations by framework O atoms in 8-ring window sites of the seven cage types present. Na+ cations in 8R sites block the access of N-2 molecules to the internal pore space at 77 K but CO2 adsorption at 308 K is observed, and is postulated to occur via a 'trapdoor' mechanism. In situ PXRD during CO2 adsorption at pressures up to 10 bar show reversible broadening of diffraction peaks that is attributed to local crystallographic strain.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/26875
- DOI
- 10.1515/ZKRI-2014-1824
- ISSN
- 2194-4946
- Article Type
- Article
- Citation
- Zeitschrift Fur Kristallographie-crystalline Materials, vol. 230, no. 4, page. 223 - 231, 2015-04
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