ANALYSIS OF DIFFERENT KINETIC-MODELS IN THE DYNAMIC PYROLYSIS OF CELLULOSE

The kinetics of the thermal decomposition of cellulose in nitrogen were studied using dynamic TG at heating rates between 5 and 50 K min(-1). The most widely used models found in the literature which are usually applied in isothermal conditions were tested. Important differences were found between models that take into account the formation of an activated cellulose and those that assume the direct decomposition of cellulose to char, tar and gases. The best agreement between experimental and calculated values was found with models which consider the formation of activated cellulose and take into account the different behaviour at low and high temperatures. The simultaneous correlation of all the experimental data obtained in different conditions is proposed as a technique to prevent compensating effects between the pre-exponential factor and the activation energy, and thus to avoid erroneous conclusions.