Kinetics Study by Thermogravimetry from Sugarcane Bagasse

摘要

Pyrolysis kinetics of sugarcane bagasse has been investigated thermogravimetrically under dynamic and stepwise conditions at different heating rates of 1, 5, 10, 20 and 40 °C/min and in a wide temperature range 20-1000°C in N_2. Three stages of weight loss are observed, where the first two stages are overlapping. The results show that the onset temperature of mass loss is within 104-156 °C and the final reaction temperature is within 423-500°C. The average mass loss is 89.5 wt.%. There are three DTG peaks located at the temperature ranges of 135-309, 276-394 and 374-500 °C, respectively. The first two peaks might be associated with either with decomposition of the major components of the sugarcane bagasse, hemicellulose and cellulose or with different processes of cellulose decomposition. The third peak is possibly associated to a lignin. At a temperature of 460 °C, the expected amount of volatiles of this waste is within 85-89%. Friedman method and a differential parallel model were used for determinate the corresponding kinetics parameters. In this work, the yield coefficients of parallel models were examined to relate the component evolution. The knowledge of the kinetics for the thermal decomposition is needed for the design of pyrolysis reactors. Activation energies calculated were 110, 215, and 35 kJ/mol for the three stages. The total weight loss of each apparent reaction was 27 wt. %, 28 wt.% and 40 wt.% with a 5 wt.% of final residue. The simulation with the model agreed well with experimental data.