ガス分析法によるMnO₂のMnOまでの炭素熱還元の研究

抄録

The reduction kinetics of Mn oxides with carbon was investigated in order to study the characteristics of pre-reduction of Mn ores and to clarify the catalytic action for the oxidation of carbon.
(1) For the reduction of MnO₂, thermal decomposition of MnO₂ occurs preferentially, and the activation energy of 175 kJ/mol, which corresponds to that for thermal decomposition of MnO₂, is obtained.
(2) At temperatures below 913 K for the reduction of Mn₂O₃, the activation energy is 226 kJ/mol and thermal decomposition of Mn₂O₃ is thought to be a rate determining step. Above 913 K, the reduction process of Mn₂O₃ seems to be controlled by the diffusion of reactant and product gases through the product layer.
(3) For the reduction of Mn₃O₄, the activation energy of 289 kJ/mol nearly equal to that for the Boudouard’s reaction is obtained and this Boudouard’s reaction seems to be catalyzed by Mn₃O₄.
(4) The nonstoichiometric MnO_1.61, MnO_1.42 and MnO_1.11 seem to be formed in the reduction process of MnO₂, Mn₂O₃, Mn₃O₄ at 843, 1003, 1153 K, respectively.