Kinetic Analysis of Construction, Renovation, and Demolition (CRD) Wood Pyrolysis Using Model-Fitting and Model-Free Methods by Thermogravimetric Analysis (TGA)

The pyrolysis of non-recyclable construction, renovation, and demolition (CRD) wood waste is a complex thermochemical process involving devolatilization, diffusion, phase transitions, and char formation. CRD wood, a low-ash biomass containing 24-32% lignin, includes both hardwood and softwood components, making it a viable heterogeneous feedstock for bioenergy production. Thermogravimetric analysis (TGA) of CRD wood residues was conducted at heating rates of 10, 20, 30, and 40°C/min up to 900°C, employing model-fitting (Coats-Redfern (CR)) and model-free (Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), Friedman (FM)) approaches to determine kinetic and thermodynamic parameters. The degradation process exhibited three stages, with peak weight loss occurring at 350-400°C. The Coats-Redfern method identified diffusion and phase interfacial models as highly correlated (R² > 0.99), with peak activation energy (Ea) at 30°C/min reaching 114.96 KJ/mol. Model-free methods yielded Ea values between 172-196 KJ/mol across conversion rates (α) of 0.2-0.8. Thermodynamic parameters showed enthalpy (ΔH) of 179-192 KJ/mol, Gibbs free energy (ΔG) of 215-275 KJ/mol, and entropy (ΔS) between -60 and -130 J/mol·K, indicating an endothermic, non-spontaneous process. These results support CRD wood’s potential for biochar production through controlled pyrolysis.