Enthalpy of formation and dehydration of lithium and sodium zeolite beta

Pingping Sun, Suraj Deore, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Zeolite Li-BEA and Na-BEA with Si/Al = 3-4 were synthesized by alumination and ion exchange, then characterized by XRD, TG-DSC and NMR. The enthalpies of formation and dehydration of Li and Na ion exchanged zeolite beta are investigated by high temperature oxide melt solution calorimetry. For Li-BEA, the formation enthalpies of formation from oxides at 25 °C are 25.6 ± 1.7 kJ/mol TO2 for the dehydrated zeolite and -8.45 ± 0.94 kJ/mol TO2 for the fully hydrated zeolite; for Na-BEA they are -2.4 ± 0.6 kJ/mol TO2 for the dehydrated and -17.8 ± 1.0 kJ/mol TO2 for the fully hydrated zeolite. The integral dehydration enthalpy at 25 °C is 33.2 ± 1.8 kJ/mol H2O for Li-BEA and 16.5 ± 1.1 kJ/mol H2O for Na-BEA. The partial molar dehydration enthalpies of both Li-BEA and Na-BEA are a linear function of water content. Molecular mechanics simulations explore the cation and water molecule positions in the framework at several water contents.

Original languageEnglish (US)
Pages (from-to)29-40
Number of pages12
JournalMicroporous and Mesoporous Materials
Volume98
Issue number1-3
DOIs
StatePublished - Jan 5 2007
Externally publishedYes

Keywords

  • Calorimetry
  • Dehydration enthalpy
  • Formation enthalpy
  • Simulation
  • Zeolite beta

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials

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