Thermal stability and pyrolysis kinetics of organosolv lignins obtained from Eucalyptus globulus

Abstract

In the present work, thermogravimetric analysis of 17 organosolv lignin samples was carried out to determine their thermal stability and calculate the kinetic parameters of their pyrolysis. The thermal stability has been estimated by the measurement of the degradation temperature ( T d), calculated according to the maximum reaction rate. In addition, degradation temperature at 10% of conversion ( T 10%) has been obtained in order to compare the initial stability of the samples with T d for all samples. The values of T d are comprised between 262 and 389 °C and the average value is 340 °C. The range for T 10% is 251–320 °C and the average value is 270 °C. The ashes content of the samples has been analyzed and all the residues presented values lower than 4 wt%. Kinetic parameters of lignin pyrolysis were calculated by Borchardt–Daniels’ method assuming nth order reaction. The activation energy values obtained are comprised between 17.9 and 42.5 kJ/mol and the average value is 28.1 kJ/mol. These results are in agreement with the bibliography.