Structural characterization of pure Na-nephelines synthesized by zeolite conversion route

Radovan Dimitrijevic, Vera Dondur, Predrag Vulic, Smilja Markovic, Slobodan I Macura

Research output: Contribution to journalArticle

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Abstract

Using the zeolite thermally induced transformation route and starting from Na-LTA, Na-FAU and Na-GIS zeolites as precursors, we synthesized pure sodium nephelines (ps-Ne) with Si/Al ratios between 1.0 and 1.5 (ps-NeLTA, ps-NeFAU, ps-NeGIS). By X-ray diffraction analysis of intermediaries, we found that ps-NeLTA and ps-NeFAU were obtained as polymorphous transformation products from carnegieite phases and ps-NeGIS was synthesized directly from amorphous zeolite precursor. Stoichiometric ps-NeLTA {Na8[Al8Si 8]16O32} and non-stoichiometric ps-Ne FAU {(Na7.200.80)8[Al 7.20Si8.80]16O32} and ps-Ne GIS {(Na6.411.59)8[Al 6.41Si9.59]16O32} were obtained at temperatures 900-1200 °C. The crystal structures of these ps-Ne-s were refined in the P63 space group, from X-ray powder data using the Rietveld method. Mean T-O bond lengths decreases almost linearly with increasing the Si/Al ratio. These changes are induced by short-range order-disorder of Si, Al cations through the TG and TS sites. The increase of short-range disorder over T-sites, is followed and confirmed by 29Si MAS NMR and IR spectroscopy. Comparison of the Si/Al ordering of synthesized ps-Ne structures with the published data shows inverse segregation of framework cations (Si; T1=T4 and Al; T2=T3). That is probably a consequence of applied synthesis route.

Original languageEnglish (US)
Pages (from-to)1623-1633
Number of pages11
JournalJournal of Physics and Chemistry of Solids
Volume65
Issue number10
DOIs
StatePublished - Oct 2004

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nepheline
Zeolites
Sodium
routes
sodium
Geographic information systems
Cations
Positive ions
disorders
Rietveld method
cations
Order disorder transitions
Bond length
zeolites
Powders
X ray diffraction analysis
Nuclear magnetic resonance spectroscopy
Infrared spectroscopy
x rays
Crystal structure

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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Structural characterization of pure Na-nephelines synthesized by zeolite conversion route. / Dimitrijevic, Radovan; Dondur, Vera; Vulic, Predrag; Markovic, Smilja; Macura, Slobodan I.

In: Journal of Physics and Chemistry of Solids, Vol. 65, No. 10, 10.2004, p. 1623-1633.

Research output: Contribution to journalArticle

Dimitrijevic, Radovan ; Dondur, Vera ; Vulic, Predrag ; Markovic, Smilja ; Macura, Slobodan I. / Structural characterization of pure Na-nephelines synthesized by zeolite conversion route. In: Journal of Physics and Chemistry of Solids. 2004 ; Vol. 65, No. 10. pp. 1623-1633.
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abstract = "Using the zeolite thermally induced transformation route and starting from Na-LTA, Na-FAU and Na-GIS zeolites as precursors, we synthesized pure sodium nephelines (ps-Ne) with Si/Al ratios between 1.0 and 1.5 (ps-NeLTA, ps-NeFAU, ps-NeGIS). By X-ray diffraction analysis of intermediaries, we found that ps-NeLTA and ps-NeFAU were obtained as polymorphous transformation products from carnegieite phases and ps-NeGIS was synthesized directly from amorphous zeolite precursor. Stoichiometric ps-NeLTA {Na8[Al8Si 8]16O32} and non-stoichiometric ps-Ne FAU {(Na7.20□0.80)8[Al 7.20Si8.80]16O32} and ps-Ne GIS {(Na6.41□1.59)8[Al 6.41Si9.59]16O32} were obtained at temperatures 900-1200 °C. The crystal structures of these ps-Ne-s were refined in the P63 space group, from X-ray powder data using the Rietveld method. Mean T-O bond lengths decreases almost linearly with increasing the Si/Al ratio. These changes are induced by short-range order-disorder of Si, Al cations through the TG and TS sites. The increase of short-range disorder over T-sites, is followed and confirmed by 29Si MAS NMR and IR spectroscopy. Comparison of the Si/Al ordering of synthesized ps-Ne structures with the published data shows inverse segregation of framework cations (Si; T1=T4 and Al; T2=T3). That is probably a consequence of applied synthesis route.",
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N2 - Using the zeolite thermally induced transformation route and starting from Na-LTA, Na-FAU and Na-GIS zeolites as precursors, we synthesized pure sodium nephelines (ps-Ne) with Si/Al ratios between 1.0 and 1.5 (ps-NeLTA, ps-NeFAU, ps-NeGIS). By X-ray diffraction analysis of intermediaries, we found that ps-NeLTA and ps-NeFAU were obtained as polymorphous transformation products from carnegieite phases and ps-NeGIS was synthesized directly from amorphous zeolite precursor. Stoichiometric ps-NeLTA {Na8[Al8Si 8]16O32} and non-stoichiometric ps-Ne FAU {(Na7.20□0.80)8[Al 7.20Si8.80]16O32} and ps-Ne GIS {(Na6.41□1.59)8[Al 6.41Si9.59]16O32} were obtained at temperatures 900-1200 °C. The crystal structures of these ps-Ne-s were refined in the P63 space group, from X-ray powder data using the Rietveld method. Mean T-O bond lengths decreases almost linearly with increasing the Si/Al ratio. These changes are induced by short-range order-disorder of Si, Al cations through the TG and TS sites. The increase of short-range disorder over T-sites, is followed and confirmed by 29Si MAS NMR and IR spectroscopy. Comparison of the Si/Al ordering of synthesized ps-Ne structures with the published data shows inverse segregation of framework cations (Si; T1=T4 and Al; T2=T3). That is probably a consequence of applied synthesis route.

AB - Using the zeolite thermally induced transformation route and starting from Na-LTA, Na-FAU and Na-GIS zeolites as precursors, we synthesized pure sodium nephelines (ps-Ne) with Si/Al ratios between 1.0 and 1.5 (ps-NeLTA, ps-NeFAU, ps-NeGIS). By X-ray diffraction analysis of intermediaries, we found that ps-NeLTA and ps-NeFAU were obtained as polymorphous transformation products from carnegieite phases and ps-NeGIS was synthesized directly from amorphous zeolite precursor. Stoichiometric ps-NeLTA {Na8[Al8Si 8]16O32} and non-stoichiometric ps-Ne FAU {(Na7.20□0.80)8[Al 7.20Si8.80]16O32} and ps-Ne GIS {(Na6.41□1.59)8[Al 6.41Si9.59]16O32} were obtained at temperatures 900-1200 °C. The crystal structures of these ps-Ne-s were refined in the P63 space group, from X-ray powder data using the Rietveld method. Mean T-O bond lengths decreases almost linearly with increasing the Si/Al ratio. These changes are induced by short-range order-disorder of Si, Al cations through the TG and TS sites. The increase of short-range disorder over T-sites, is followed and confirmed by 29Si MAS NMR and IR spectroscopy. Comparison of the Si/Al ordering of synthesized ps-Ne structures with the published data shows inverse segregation of framework cations (Si; T1=T4 and Al; T2=T3). That is probably a consequence of applied synthesis route.

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