Critical insights into pyrolysis and co-pyrolysis of poplar and eucalyptus wood sawdust: Physico-chemical characterization, kinetic triplets, reaction mechanism, and thermodynamic analysis

Critical information on physico-chemical characterization, thermo-kinetics, and thermodynamic parameters for pyrolysis of lignocellulosic biomass are vital for safe and efficient design of biomass pyrolysis reactors. In the present investigation, physico-chemical characterization, pyrolysis and co-pyrolysis kinetics, and thermodynamic analysis of poplar wood (PW), eucalyptus wood (EW), and their binary blend (MW) were studied via TGA-thermograms obtained at 5, 10, and 20 °C/min under nitrogen atmosphere. The kinetic parameters were computed via model-fitting (inflection point and multiple linear regression) and model-free (OFW and KAS) methods. Both approaches predicted a different set of kinetic triplets where E-value from model-fitting (73.20 ± 1.57, 55.68 ± 1.34, 65.56 ± 1.18 kJ/mol for PW, EW, and MW) and model-free (173.86 ± 0.48, 210.53 ± 0.39, and 203.47 ± 0.23 kJ/mol for PW, EW, and MW) methods was predicted. Endothermicity, degree of stability, and energy barrier were found to be in the order of EW > MW > PW, EW > MW = PW, and EW = MW > PW, respectively. Further, behavior of pyrolysis reaction was established with the help of Criado method using Z(α) master plots. At initial conversion, diffusional processes predominate which was best described by D₁ (1-D diffusion; Parabola law) and thereafter nuclei grew according to first- and third-order reaction models.