Energetics of a nanophase zeolite independent of particle size

Qinghua Li, Sanyuan Yang, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Silicalite-1 nanocrystals were synthesized with different sizes (40, 95 and 180 nm) from clear solutions and the organic structure directing agent removed by calcination. X-ray diffraction, scanning electron microscopy, nitrogen adsorption, Fourier transform infrared spectroscopy and thermogravimetric analysis were used for characterization. High-temperature solution calorimetry using lead borate (2PbO · B2O3) solvent at 974 K measured the enthalpies (ΔHtran) relative to quartz at 298 K. The ΔHtran values are 8.2 ± 0.4 kJ/mol (40 nm), 8.3 ± 0.3 kJ/mol (95 nm) and 8.0 ± 0.5 kJ/mol (180 nm). These values are essentially the same as ΔHtran for microsized MFI crystals, 8.0 ± 0.8 kJ/mol [J. Phys. Chem. B 104 (2000) 10001]. Thus the particle size has no effect on the framework energetics of silicalite. This unusual phenomenon, which is different from that of condensed nanocrystalline metal oxides, is discussed in terms of internal surface area and surface energy of zeolites.

Original languageEnglish (US)
Pages (from-to)137-143
Number of pages7
JournalMicroporous and Mesoporous Materials
Volume65
Issue number2-3
DOIs
StatePublished - Nov 4 2003
Externally publishedYes

Keywords

  • Enthalpy of transition
  • Nanocrystalline zeolite
  • Silicalite-1
  • Surface area

ASJC Scopus subject areas

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

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