Isoconversional kinetic analysis of sweet sorghum bagasse pyrolysis by modified logistic mixture model

Abstract

In order to overcome the noise problem when analyzing the experimental thermogravimetric analysis data and obtain the temperature values at different heating rates for various conversions, a modified logistic mixture model, the combination of two modified logistic functions and a constant, has been presented for fitting all thermogravimetric analysis curves at different heating rates. The thermogravimetric analysis curves of sweet sorghum bagasse pyrolysis at three heating rates of 15, 25 and 35 K min−1 were analyzed. The modified logistic mixture model and logistic mixture model were used for fitting the experimental thermogravimetric analysis curves at all heating rates. The results have shown that the modified logistic mixture model fitted the experimental data better than the logistic mixture model. Making use of the data calculated by the modified logistic mixture model, the effective activation energy values as a function of conversion were obtained by means of the Friedman isoconversional method. The effective activation energies varied from 150 to 320 kJ mol−1 when the conversion ranged from 0.05 to 0.85, which indicated that the pyrolysis of sweet sorghum bagasse was a complex process.