Energetics of Alkali and Alkaline Earth Ion-Exchanged Zeolite A

Hui Sun, Di Wu, Kefeng Liu, Xiaofeng Guo, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Alkali and alkaline earth ion-exchanged zeolite A samples were synthesized in aqueous exchange media. They were thoroughly studied by powder X-ray diffraction (XRD), electron microprobe (EMPA), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and high temperature oxide melt solution calorimetry. The hydration energetics and enthalpies of formation of these zeolite A materials from constituent oxides were determined. Specifically, the hydration level of zeolite A has a linear dependence on the average ionic potential (Z/r) of the cation, from 0.894 (Rb-A) to 1.317 per TO2 (Mg-A). The formation enthalpies from oxides (25 °C) range from -93.71 ± 1.77 (K-A) to -48.02 ± 1.85 kJ/mol per TO2 (Li-A) for hydrated alkali ion-exchanged zeolite A, and from -47.99 ± 1.20 (Ba-A) to -26.41 ± 1.71 kJ/mol per TO2 (Mg-A) for hydrated alkaline earth ion-exchanged zeolite A. The formation enthalpy from oxides generally becomes less exothermic as Z/r increases, but a distinct difference in slope is observed between the alkali and the alkaline earth series.

Original languageEnglish (US)
Pages (from-to)15251-15256
Number of pages6
JournalJournal of Physical Chemistry C
Volume120
Issue number28
DOIs
StatePublished - Jul 21 2016

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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