Kinetics and mechanism of the oxidation of carbon by NO2 in the presence of water vapor

The kinetics and mechanism of the oxidation of carbon by NO2 in absence and presence of water vapor were studied in a fixed bed reactor. The rate of carbon oxidation by NO2 is enhanced in the presence of water vapor in the range of temperature 300–400°C. The benefit effect of water is attributed to the intermediate formation of traces of nitric and nitrous acids, which enhance the rate of the carbon oxidation without modifying the global mechanism reaction. Therefore, water acts as a catalyst for the carbon oxidation by NO2. A kinetic mechanism derived from this parametric study shows a decrease in the activation energy of carbon oxidation by NO2 in the presence of water vapor. This result is in agreement with the experimental observation. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 236–244, 2009