Resumo

OJEDA, M. W.; RIVAROLA, J. B.  e  QUIROGA, O. D.. Carbochlorination of molybdenum trioxide: kinetic treatment. Lat. Am. appl. res. [online]. 2003, vol.33, n.2, pp.195-200. ISSN 0327-0793.

The kinetics of MoO₃ chlorination in the presence of carbon is analyzed. The experimental data were obtained in a fixed-bed isothermal reactor, operated at atmospheric pressure between 543 and 603 K, and at different feed flows and Cl₂ concentrations. The following global reaction was obtained by identification of the reaction products: 2 MoO_3(s) + 2 Cl_2(g) + C_(s) ® 2 MoO₂Cl_2(g) + CO_2(g). On the basis of the analysis of experimental data, thermodynamic results and observations by other authors, three basic stages are distinguished: 1) Formation of the chlorinating agent; 2) Chlorination of molybdenum trioxide; 3) Carbon oxidation. This mechanism allows to explain the greater reactivity of carbochlorination reactions at low temperatures as compared to direct chlorination. A detailed scheme is proposed for the kinetic treatment, which reveals that 22 stages are involved in this complex reaction. The experimental data were processed with different kinetic models, and it was found that the"nucleation and growth"model, conveniently adapted to non catalyzed heterogeneous reactions is the one that better matches the experimental data.

Palavras-chave : Carbochlorination; Molybdenum Trioxide; Kinetic Treatment.

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