In situ 119Sn-mössbauer spectroscopic study on MFI, MEL, and MTW tin silicalites

K. Lázár, A. M. Szeleczky, N. K. Mal, A. V. Ramaswamy

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

MPI, MEL, and MTW analogue tin silicalites were studied by in situ Mössbauer spectroscopy to complement previous studies. Series of 77 and 300 K spectra were obtained from synthesized, reduced, and oxidized samples. Intensity changes of components as a function of temperature (d InA/dT values) were also considered in addition to the usual spectral parameters (isomer shift and quadrupole splitting) to evaluate the spectra. The data obtained for Sn(IV) support neither the octahedral nor the extraframework emplacement; instead, dominance of tetrahedral coordination is supported. Upon reduction in hydrogen a Sn(II) component is formed and can be stabilized. A significant portion of Sn(II) can be reoxidized to the Sn(IV) state by a subsequent medium oxidation. In view of the respective d InA/dT values and the stabilization of Sn(II), the structural change of edge-sharing [SnO4/2] tetrahedra is suggested to form Si-O-Sn(II)-O-Si bridges. The existence of these bridges also can be correlated with the catalytic activity of tin silicalites observed in mild oxidation processes.

Original languageEnglish
Pages (from-to)123-127
Number of pages5
JournalZeolites
Volume19
Issue number2-3
DOIs
Publication statusPublished - Jan 1 1997

    Fingerprint

Keywords

  • Isomorphous substitution
  • Structural defects
  • Tin silicalites
  • sn mössbauer spectroscopy

ASJC Scopus subject areas

  • Environmental Science(all)

Cite this