Kinetics of carbochlorination of chromium (III) oxide

International audienceKinetics of the carbochlorination of Cr2O3 has been studied with Cl2+CO gas mixtures between 500 °C to 900 °C using thermogravimetric analysis. The apparent activation energy is about 100 kJ/mol. Mathematical fitting of the experimental data suggests that the shrinking sphere model is the most adequate to describe the carbochlorination mechanism of chromium oxide and that is controlled by the chemical reaction. In the temperature range of 550 °C to 800 °C, the reaction order is about 1.34 and is independent of temperature. Changing the Cl2+CO content from 15 to 100 pct increases the reaction rate and does not affect the reaction mechanism. Similarly, changing the ratio of Cl2/(Cl2+CO) from 0.125 to 0.857 does not modify the carbochlorination mechanism of Cr2O3. In these conditions, the reaction rate passes through a maximum when using a chlorinating gas mixture having a Cl2/(Cl2+CO) ratio of about 0.5