The steric influence of extra-framework cations on framework flexibility: An LTA case study

Mero Lee U. Cornelius, Lisa Price, Stephen A. Wells, Leslie F. Petrik, Asel Sartbaeva

Research output: Contribution to journalArticle

Abstract

The theoretical extent of framework flexibility of Zeolite A (LTA) in response to the steric and geometric effects of different Si/Al compositions and extra-framework cation content has been explored using GASP software. Flexibility windows and compression mechanisms for siliceous LTA and aluminosilicate Na-LTA, Ca-LTA and K-LTA have been modelled. As expected, relatively small cations in the zeolite pores have little effect on the range of flexibility observed. Aluminosilicate LTA, Na-LTA and Ca-LTA frameworks exhibit identical flexibility windows and these frameworks also follow the same compression mechanisms. The introduction of larger K+ ions, however, results in greater steric hindrance. This restricts the flexibility of the framework and alters the compression mechanism to accommodate these larger cations. It is shown that the limits of the flexibility window of Zeolite A are dependent on framework aluminium content and extra-framework cation size.

Original languageEnglish
Pages (from-to)461-468
Number of pages8
JournalZeitschrift fur Kristallographie - Crystalline Materials
Volume234
Issue number7-8
Early online date16 Jul 2019
DOIs
Publication statusPublished - 26 Jul 2019

Keywords

  • cation
  • compression
  • extra-framework
  • flexibility
  • flexibility window
  • framework
  • GASP
  • geometric simulation
  • steric interaction
  • structure-breaking
  • structure-directing
  • template
  • template based geometric simulation
  • zeolite

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Inorganic Chemistry

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