Application of a nonisothermal thermogravimetric method to the kinetic study of the reduction of metallic oxides; Part 1. A general treatment and its application to the reduction of the oxides of molybdenum by hydrogen
- Dept. of Theoretical Metallurgy, Royal Inst. of Technology, S-100 44 Stockholm (SE)
In this paper a theoretical treatment to evaluate activation energies of reactions by means of nonisothermal experiments is developed. The treatment considers the case where either the surface reaction or the intraparticle diffusion could be rate-controlling. Complementary to the theoretical treatment, thermogravimetric experiments have been carried out under both isothermal and nonisothermal conditions. The reduction of MoO{sub 3} to Mo was found to pass through an intermediate MoO{sub 2} phase. The rate of reduction to MoO{sub 2} seems to be controlled by surface reaction, and the activation energy obtained from isothermal studies is 205.7 kJ/mol. This is comparable to the value of 211.6 kJ/mol obtained from nonisothermal reduction studies using the present theoretical treatment. The rate of reduction to Mo appears to be influenced by gas diffusion through voids. The activation energy from isothermal studies is 85.2 kJ/mol.
- OSTI ID:
- 7177227
- Journal Information:
- Metallurgical Transactions, B (Process Metallurgy); (United States), Vol. 23B; ISSN 0360-2141
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
08 HYDROGEN
74 ATOMIC AND MOLECULAR PHYSICS
MOLYBDENUM OXIDES
HYDROGEN EMBRITTLEMENT
REDOX REACTIONS
ACTIVATION ENERGY
CHEMICAL REACTION KINETICS
DIFFUSION
ISOTHERMAL PROCESSES
PHASE STUDIES
TEMPERATURE EFFECTS
THERMAL GRAVIMETRIC ANALYSIS
VOID FRACTION
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
EMBRITTLEMENT
ENERGY
GRAVIMETRIC ANALYSIS
KINETICS
MOLYBDENUM COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
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Cermets
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080800 - Hydrogen- Properties & Composition
664400 - Experimentally Derived Information on Atomic & Molecular Properties- (1992-)