Pyrolytic Pathway of Wheat Straw Pellet by the Thermogravimetric Analyzer

Abstract

The study of the thermokinetics of two types of wheat straw pellets, T1 (100% wheat straw) and T2 (70% wheat straw, 10% each of bentonite clay, sawdust, and biochar), under a nitrogen atmosphere (31–800 °C and 5, 10, and 20 °C/min heating rates) using model-free and model-based approaches by TG/DTG data, revealed promising results. While model-free methods were not suitable, model-based reactions, particularly Fn (nth-order phase interfacial) and F2 (second-order) models, effectively described the three-phase consecutive thermal degradation pathway (A→B, C→D, and D→E). The activation energy (Eα) for phases 2 and 3 (Fn model) averaged 136.04 and 358.11 kJ/mol for T1 and 132.86 and 227.10 kJ/mol for T2, respectively. The pre-exponential factor (lnA) varied across heating rates and pellets (T2: 38.244–2.9 × 109 1/s; T1: 1.2 × 102–5.45 × 1014 1/s). Notably, pellets with additives (T2) exhibited a higher degradable fraction due to lower Eα. These findings suggest a promising potential for utilizing wheat straw pellet biomass as a bioenergy feedstock, highlighting the practical implications of this research.