Application of a nonisothermal thermogravimetric method to the kinetic study of the reduction of metallic oxides: Part 2. A theoretical treatment of powder bed reduction and its application to the reduction of tungsten oxide by hydrogen

Journal Article · Tue Jun 01 00:00:00 EDT 1993 · Metallurgical Transactions, B (Process Metallurgy); (United States)

DOI:https://doi.org/10.1007/BF02666430· OSTI ID:7368976

Bustnes, J A; Sichen, D; Seetharaman, S ^[1]

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1. Royal Inst. of Tech., Stockholm (Sweden). Department of Theoretical Metallurgy

Theoretical treatment of nonisothermal kinetic studies has been extended in the present work to gas-solid reactions in powder beds. An expression for the activation energies for the reaction has been derived on the basis that the reaction proceeds by the movement of the reaction front, the velocity of the movement being kept constant. The reliability of the method has been tested by applying the same to the reduction of tungsten oxide by hydrogen. The experiments were carried out using thermogravimetric technique under both isothermal and nonisothermal conditions. The reaction front is considered to consist of a thin layer of small particles. The rate of the reduction seems to be controlled by the chemical reaction between the product and the unreacted core existing in each of the small particles. Using the expression derived in the present work, the activation energy of the reaction was calculated from the results of the nonisothermal experiments to be 83.62 kJ/mol. This value is in good agreement with the value of 83.17 kJ/mol evaluated from isothermal experiments.

• OSTI ID: 7368976
• Journal Information: Metallurgical Transactions, B (Process Metallurgy); (United States), Vol. 24:3; ISSN 0360-2141
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
TUNGSTEN OXIDES
REDUCTION
ACTIVATION ENERGY
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
GASES
HYDROGEN
MATHEMATICAL MODELS
PACKED BEDS
SOLIDS
THERMAL GRAVIMETRIC ANALYSIS
CHALCOGENIDES
CHEMICAL ANALYSIS
ELEMENTS
ENERGY
FLUIDS
GRAVIMETRIC ANALYSIS
KINETICS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
THERMAL ANALYSIS
TRANSITION ELEMENT COMPOUNDS
TUNGSTEN COMPOUNDS
400201* - Chemical & Physicochemical Properties