Kinetics of chlorination and carbochlorination of molybdenum trioxide

Abstract

Kinetics of chlorination of MoO₃ with Cl₂-air, Cl₂-N₂, and Cl₂-CO-N₂ gas mixtures have been studied by nonisothermal and isothermal thermogravimetric measurements, between ambient temperature and 900 °C. Between 500 °C and 700 °C, the chlorination reaction of MoO₃ with Cl₂-N₂ gas mixture has an apparent activation energy of about 165 kJ/mole, reflecting that a chemical reaction is the rate-controlling step. The reaction order with respect to Cl₂ partial pressure is about 0.75. The apparent activation energy for carbochlorination with Cl₂-CO-N₂ gas mixture is about 83 kJ/mole, between 400 °C and 650 °C. The carbochlorination of MoO₃ was controlled by the chemical reaction, probably affected by the pore diffusion regime. The maximum reaction rate is obtained by using a Cl₂-CO-N₂ gas mixture, having a Cl₂/CO volume ratio equal to about 1. The total apparent reaction order with respect to Cl₂ + CO in Cl₂-CO-N₂ gas mixture is about 1.5 for a Cl₂/CO ratio equal to 1.