Thermogravimetric Studies on the Global Kinetics of Carbon Gasification in Nitrous Oxide

The global kinetics of the carbon gasification in N 2 O were determined with a thermogravimetric system. The carbon was a phenol−formaldehyde resin char of low impurity levels, and the burn-off range of the carbon in this study was 0−45%. The temperature range studied was 673−923 K, and the partial pressure of N 2 O was varied from 10.1 to 101 kPa. The kinetics can be divided into two temperature regimes. The low-temperature regime (<748 K) is characterized by an activation energy, which increases slightly with the extent of carbon burn-off, ranging from 57 to 66 kJ/mol. The high-temperature regime (>748 K) is exhibited by an activation energy, which is also an increasing function of the burn-off level, ranging from 170 to 230 kJ/mol. The reaction order with respect to the N 2 O partial pressure is not constant. The rate of gasification increases with the N 2 O pressure to a maximum and then begins to decrease with a further increase of the pressure.