Calculation of Kinetic Parameters of the Thermal Decomposition of Wood by Distributed Activation Energy Model (DAEM)

L. Gašparovič, J. Labovský, J. Markoš and L. Jelemenský

Abstract
This work deals with pyrolysis decomposition of wood chips and the main components of wood by thermogravimetric analysis (TGA). Experiments were carried out in the inert atmosphere of nitrogen. The pyrolysis temperature range was varied linearly from 20 °C to 900 °C with the heating rate equal to 5 K min–1 to detect all the changes without overlapping. Samples of cellulose, hemicellulose and lignin were used as main components of wood. Thermogravimetric (TG) and differential thermogravimetric (DTG) curves were obtained from experimental data. These records were compared with those obtained by mathematical modeling. The distribution activation energy model (DAEM) was used for mathematical description of experimental data and the prediction of kinetic parameters. According to the DAEM approach, every possible decomposition reaction with various values of activation energies is in progress at each time and temperature. Preexponential factors, mean activation energy and variance were obtained as kinetic parameters. This model is able to describe the integral decomposition curve of biomass, however, a problem occurs when describing the differential curve of biomass thermal decomposition. In general, this model does not accurately describe the decomposition of materials, which are a mixture of several compounds.

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Keywords
kinetics, biomass, TGA, thermal decomposition, DAEM