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Journal of thermal analysis

, Volume 37, Issue 5, pp 891–906 | Cite as

Reactivity with hydrogen of pure iron oxide and of iron oxides doped with oxides of Mn, Co, Ni and Cu

  • D. N. Drakshayani
  • R. M. Mallya
Article

Abstract

Using dynamic TG in H2, X-ray powder diffraction and Mössbauer Spectroscopy the reactivities fot hydrogen reduction of Fe2O3 prepared at different temperatures, Fe2O3 doped with oxides of Mn, Co, Ni and Cu prepared at 300‡C from nitrate precursors and intermediate spinels derived from above samples during reduction have been explored. The reactivity is higher for finely divided Fe2O3 prepared at 250‡C. The reduction is retarded by Mn, marginally affected by Co and accelerated by Ni and Cu, especially at higher (5 at.%) dopant concentration. These reactivities confirmed also by isothermal experiments, are ascribed to the nature of disorder in the metastable intermediate spinels and to hydrogen ’spill over’ effects.

Keywords

Nitrate Fe2O3 Iron Oxide Powder Diffraction Dopant Concentration 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Zusammenfassung

Mittels Debye-Scherrer-Aufnahmen, Mössbauer-Spektroskopie und DTG in WasserstoffatmosphÄre wurde die ReaktivitÄt bezüglich der Reduktion mit Wasserstoff von Fe2O3, versetztem Fe2O3 und von intermediÄren Spinellen aus der Reduktion obiger Proben untersucht. Die reinen Fe2O3-Proben wurden bei verschiedenen Temperaturen hergestellt. Mit Oxiden von Mn, Co, Ni und Cu versetzte Fe2O3-Proben wurden bei 300C aus Nitrat-VorlÄufern hergestellt. Eine höhere AktivitÄt besteht für fein zerkleinertes, bei 250‡C hergestelltes Fe2)O3. Die Reduktion wird durch Mn verzögert, durch Co unwesentlich beeinflu\t und durch Ni und Cu beschleunigt, besonders bei höheren Konzentrationen (5 mol%). Diese ReaktivitÄten, die auch durch isotherme Experimente bestÄtigt werden konnten, wurden der Ungeordnetheit in den metastabilen intermediÄren Spinellen sowie Wasserstoff-“überschu\”-Effekten zugeschrieben.

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Copyright information

© Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest 1991

Authors and Affiliations

  • D. N. Drakshayani
    • 1
  • R. M. Mallya
    • 1
  1. 1.Department of MetallurgyIndian Institute of ScienceBangaloreIndia

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