Sustainable Renewable Biofuel Production Toward Pyrolysis of Fibers Biowaste Agave Americana L . and Thermodynamics Mechanisms Kinetic Parameters Triplet Assessment

Abstract

This study explores the thermal degradation behavior and pyrolysis kinetics of fibers derived from the flower stalk of Agave americana waste (FSSAW), aiming to assess their suitability for bioenergy applications. Non-isothermal thermogravimetric analysis (TGA) was conducted at heating rates of 30, 40, and 50 °C/min. Kinetic modeling using the Coats – Redfern method evaluated 36 solid-state reaction models to determine the activation energy-Ea and pre-exponential factor (lnA). The highest Ea was observed for Model M22, increasing from 218.87 kJ/mol at 30 °C/min to 252.73 kJ/mol at 50 °C/min, while the lowest Ea, 4.22 kJ/mol, was recorded for Model M19. These results indicate the presence of both complex and simple reaction mechanisms, with a general increase in Ea at higher heating rates, consistent with the kinetic compensation effect. Thermodynamic analysis revealed a maximum enthalpy change (ΔH) of 249.65 kJ/mol, a maximum Gibbs free energy change (ΔG) of 390.81 kJ/mol, and a minimum entropy change (ΔS) of −0.31 kJ/mol·K, confirming that the pyrolysis process is endothermic and non-spontaneous, leading to a more ordered transition state. Criado’s master plot technique further validated Model M16 (random nucleation and growth) as the most representative mechanism during early decomposition stages. However, deviations at higher conversions suggest the occurrence of multi-step processes, including diffusion and char formation.