Abstract
A theoretical treatment to evaluate activation energies of reactions by means of nonisothermal experiments was developed. The treatment considers the case where either the surface reaction or the intraparticle diffusion could be rate-controlling. Complementary to the theoretical treat-ment, thermogravimetric experiments have been carried out under both isothermal and noniso-thermal conditions. The reduction of MoO3 to Mo was found to pass through an intermediate MoO2 phase. The rate of reduction to MoO2 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.
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Sichen, D., Seetharaman, S. Application of a nonisothermal thermogravimetric method to the kinetic study of the reduction of metallic oxides: Part I. A general treatment and its application to the reduction of the oxides of molybdenum by hydrogen. Metall Trans B 23, 317–324 (1992). https://doi.org/10.1007/BF02656287
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DOI: https://doi.org/10.1007/BF02656287