Enthalpies of formation of microporous titanosilicates ETS-4 and ETS-10

Hongwu Xu, Yiping Zhang, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

30 Scopus citations

Abstract

The energetics of microporous titanosilicates ETS-4 (K0.61Na1.09Ti1.10Si4.98 O13 - 2.89H2O) has been investigated by high-temperature drop solution calorimetry using lead borate as the solvent at 974 K. Combining the measured heats of drop solution with the published enthalpies of drop solution and formation for the constituent oxides, the standard enthalpies of formation from the oxides (ΔH0f.ox) and from the elements (ΔH0f.e1) for both phases were derived for the first time. The obtained values (in kJ/mol) are as follows: ΔH0f.ox(ETS-4) = -818.5 ± 13.1, ΔH0f.e1(ETS-4) = - 14, 642.8 ± 15.9, ΔH0f.ox(ETS-10) = -262.2 ± 3.1, and ΔH0f.e1(ETS-10) = -6995.2 ± 6.1. Comparison between the ΔH0f.ox (or ΔH0f.e1) values of the two phases suggests that ETS-4 is thermodynamically more stable than ETS-10 with respect to the oxides (or the elements) at 298 K and 1 atm. This behavior can largely be attributed to the higher degree of hydration of ETS-4 than that of ETS-10.

Original languageEnglish (US)
Pages (from-to)285-291
Number of pages7
JournalMicroporous and Mesoporous Materials
Volume47
Issue number2-3
DOIs
StatePublished - Oct 2001
Externally publishedYes

Keywords

  • ETS-10
  • ETS-4
  • Energetics
  • Enthalpy of formation
  • Titanosilicate

ASJC Scopus subject areas

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

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