Partial thermal reduction of ammonium paratungstate tetrahydrate: Evolved gas analysis (TG/DTA-MS) and solid state studies (XRD, FTIR)

I. M. Szilágyi, J. Madarász, F. Hange, G. Pokol

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24 Citations (Scopus)

Abstract

Thermal decomposition of ammonium paratungstate tetrahydrate, (NH 4)10[H2W12O42] •4H2O has been followed by simultaneous TG/DTA and online evolved gas analysis (TG/DTA-MS) in flowing 10% H2/Ar directly up to 900°C. Solid intermediate products have been structurally evaluated by FTIR spectroscopy and powder X-ray diffraction (XRD). A previously unexplained exothermic heat effect has been detected at 700-750°C. On the basis of TG/DTA as well as H2O and NH3 evolution curves and XRD patterns, it has been assigned to the formation and crystallization heat of γ-tungsten-oxide (WO2.72/W18O49) from β-tungsten-oxide (WO2.9/W20O58) and residual ammonium tungsten bronze.

Original languageEnglish
Pages (from-to)139-144
Number of pages6
JournalJournal of Thermal Analysis and Calorimetry
Volume88
Issue number1
DOIs
Publication statusPublished - Apr 2007

Fingerprint

Gas fuel analysis
gas analysis
Ammonium Compounds
Differential thermal analysis
Tungsten
thermal analysis
tungsten oxides
solid state
X ray diffraction
diffraction
Oxides
x rays
Bronze
bronzes
heat of formation
Crystallization
Thermal effects
X ray powder diffraction
Diffraction patterns
thermal decomposition

Keywords

  • FTIR spectroscopy
  • Mass spectrometry
  • Simultaneous TG/DTA
  • Tungsten
  • X-ray diffraction

ASJC Scopus subject areas

  • Chemical Engineering(all)

Cite this

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abstract = "Thermal decomposition of ammonium paratungstate tetrahydrate, (NH 4)10[H2W12O42] •4H2O has been followed by simultaneous TG/DTA and online evolved gas analysis (TG/DTA-MS) in flowing 10{\%} H2/Ar directly up to 900°C. Solid intermediate products have been structurally evaluated by FTIR spectroscopy and powder X-ray diffraction (XRD). A previously unexplained exothermic heat effect has been detected at 700-750°C. On the basis of TG/DTA as well as H2O and NH3 evolution curves and XRD patterns, it has been assigned to the formation and crystallization heat of γ-tungsten-oxide (WO2.72/W18O49) from β-tungsten-oxide (WO2.9/W20O58) and residual ammonium tungsten bronze.",
keywords = "FTIR spectroscopy, Mass spectrometry, Simultaneous TG/DTA, Tungsten, X-ray diffraction",
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T2 - Evolved gas analysis (TG/DTA-MS) and solid state studies (XRD, FTIR)

AU - Szilágyi, I. M.

AU - Madarász, J.

AU - Hange, F.

AU - Pokol, G.

PY - 2007/4

Y1 - 2007/4

N2 - Thermal decomposition of ammonium paratungstate tetrahydrate, (NH 4)10[H2W12O42] •4H2O has been followed by simultaneous TG/DTA and online evolved gas analysis (TG/DTA-MS) in flowing 10% H2/Ar directly up to 900°C. Solid intermediate products have been structurally evaluated by FTIR spectroscopy and powder X-ray diffraction (XRD). A previously unexplained exothermic heat effect has been detected at 700-750°C. On the basis of TG/DTA as well as H2O and NH3 evolution curves and XRD patterns, it has been assigned to the formation and crystallization heat of γ-tungsten-oxide (WO2.72/W18O49) from β-tungsten-oxide (WO2.9/W20O58) and residual ammonium tungsten bronze.

AB - Thermal decomposition of ammonium paratungstate tetrahydrate, (NH 4)10[H2W12O42] •4H2O has been followed by simultaneous TG/DTA and online evolved gas analysis (TG/DTA-MS) in flowing 10% H2/Ar directly up to 900°C. Solid intermediate products have been structurally evaluated by FTIR spectroscopy and powder X-ray diffraction (XRD). A previously unexplained exothermic heat effect has been detected at 700-750°C. On the basis of TG/DTA as well as H2O and NH3 evolution curves and XRD patterns, it has been assigned to the formation and crystallization heat of γ-tungsten-oxide (WO2.72/W18O49) from β-tungsten-oxide (WO2.9/W20O58) and residual ammonium tungsten bronze.

KW - FTIR spectroscopy

KW - Mass spectrometry

KW - Simultaneous TG/DTA

KW - Tungsten

KW - X-ray diffraction

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