Reactivity of V2O5, MoO5 and WO3 in molten KNO3, studied by mass spectormetry
Reactivity of V2O5, MoO5 and WO3 in molten KNO3, studied by mass spectormetry
The reactivity of transition metal oxides MoO3, WO3 and V2O5 in molten KNO3 was studied by mass spectrometry of the gases evolved during heating, and X-ray diffraction of the solidified melts. The reaction stoichiometry showed that multistep reactions of the polyoxoanions occur. Intermediate products identified in the reactions of the oxides are hexa- and pentavanadates, tri- and dimolybdates, and ditungstate. After prolonged heating at 550°C, the reactions proceeded to form the monooxoanions: VO3^(?), MoO4^(2?) and WO4^(2?). The reactivity of the oxides decrease in the sequence: V2O5>MoO3>WO3, the inverse of the oxoacidity sequence deduced from the equilibria in ionic melts (WO3>MoO3>V2O5). The first reaction peak is determined by kinetics of the solid–liquid reaction, whereas further transformations of polyoxospecies are determined by their oxoacidity.
molten nitrate, molybdenum, tungsten vanadium, oxoacidity
97-102
Afanaviev, P.
0e530895-7685-4583-a376-81be136b5a0e
Kerridge, D.H.
a1f0d409-03aa-4006-b993-b7fcbbf0932b
2001
Afanaviev, P.
0e530895-7685-4583-a376-81be136b5a0e
Kerridge, D.H.
a1f0d409-03aa-4006-b993-b7fcbbf0932b
Afanaviev, P. and Kerridge, D.H.
(2001)
Reactivity of V2O5, MoO5 and WO3 in molten KNO3, studied by mass spectormetry.
Journal of Alloys and Compounds, 322 (1-2), .
(doi:10.1016/S0925-8388(01)00955-0).
Abstract
The reactivity of transition metal oxides MoO3, WO3 and V2O5 in molten KNO3 was studied by mass spectrometry of the gases evolved during heating, and X-ray diffraction of the solidified melts. The reaction stoichiometry showed that multistep reactions of the polyoxoanions occur. Intermediate products identified in the reactions of the oxides are hexa- and pentavanadates, tri- and dimolybdates, and ditungstate. After prolonged heating at 550°C, the reactions proceeded to form the monooxoanions: VO3^(?), MoO4^(2?) and WO4^(2?). The reactivity of the oxides decrease in the sequence: V2O5>MoO3>WO3, the inverse of the oxoacidity sequence deduced from the equilibria in ionic melts (WO3>MoO3>V2O5). The first reaction peak is determined by kinetics of the solid–liquid reaction, whereas further transformations of polyoxospecies are determined by their oxoacidity.
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Published date: 2001
Keywords:
molten nitrate, molybdenum, tungsten vanadium, oxoacidity
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Local EPrints ID: 22824
URI: http://eprints.soton.ac.uk/id/eprint/22824
ISSN: 0925-8388
PURE UUID: 9ebe0fb4-03e8-4936-a301-01a6140cce39
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Date deposited: 24 Mar 2006
Last modified: 15 Mar 2024 06:41
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Author:
P. Afanaviev
Author:
D.H. Kerridge
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