Assessments of pyrolysis kinetics and mechanisms of biomass residues using thermogravimetry

Pyrolysis kinetics and mechanisms of two biomass residues (SB1 and SB2) were assessed by using thermogravimetric techniques. Physico-chemical, spectroscopic and TG/DTG analyses show slight variation in the chemical compositions of residues. Analysis of thermogravimetric data by Z(α) master plot method indicates that the thermal decompositions of both residues initially follow nucleation models, which gradually change to three dimensional diffusion model. Apparent activation energies of both residues, determined by various isoconversional methods are in the range of 180-380 kJ mol−1. Dependence of activation energies on fractional conversions and nonparallel nature of Friedman plots also support the results obtained from master plot method. Arrhenius constants determined from Friedman activation energy values are in the range of 1.74 × 1018-5.78 × 1023 min−1 for SB1 and 1.61 × 1020-5.31 × 1023 min−1 for SB2. Our results also demonstrate that combination of FWO or KAS method with Friedman method is a powerful tool for estimating apparent activation energies of biomass residues.