Evaluating the kinetic triplet parameters, mechanisms, and thermodynamics involved in the pyrolysis of Chamaerops humilis waste cellulosic fibers to produce sustainable and renewable biofuels

Abstract

Biomass has become a promising renewable energy source, driven by the decreasing supply of fossil fuels and ongoing environmental problems related to their use. Understanding biomass pyrolysis characteristics is essential, as it offers valuable insights and guidance for developing and improving the pyrolysis process. A thermogravimetric analysis (TGA) in a nitrogen atmosphere was conducted to examine the pyrolysis features and kinetic parameters of Chamaerops humilis fibers (ChFs). The temperature range was from 20 to 800 °C, with heating rates (β) of 30, 40, and 50 °C·min⁻¹ . The kinetic and thermodynamic properties, chemical reactions, and thermal degradation behaviors of ChFs were studied using TGA and Fourier Transform Infrared (FTIR) spectroscopy, which was applied to analyze the functional groups in the raw biomass before pyrolysis. Thirty-six kinetic models for four key solid-phase reaction steps were tested using the Coats-Redfern method. The reaction model's pre-exponential factor (A), ranging from 7.46 to 7.64 for all heating rates, was identified as the best fit, assuming random nucleation and its subsequent growth g(α)= \[−ln(1 −α) ⁴]. Activation energy (E_a) values of 218.87, 230.49, and 252.73 kJ·mol⁻¹ were obtained at 30, 40, and 50 °C·min⁻¹ , respectively. These kinetic parameters were used to calculate thermodynamic properties, including the enthalpy change (ΔH), Gibbs free energy change (ΔG), and entropy change (ΔS). The thermodynamic data suggest that ChF's pyrolysis is an endothermic process that lacks spontaneity.