isothermal pyrolysis of low-rank coal: kinetic study, batch experiments, and product analysis

Effective use of low-grade coal is crucial for meeting global energy needs and mitigating environmental impacts, making the study of its thermal decomposition a key focus for sustainable energy development. understanding the pyrolytic degradation process of coal is crucial for optimizing its use in eco-friendly energy solutions. it is hypothesized that the isothermal pyrolysis of low-rank coal at different temperatures will exhibit different kinetic behaviors and produce valuable condensable products. this research investigates the pyrolytic behavior, kinetics, and batch pyrolysis of low-rank coal. thermo-gravimetric analysis was conducted under isothermal conditions at temperatures ranging from 350 to 500 °c, with a 25 °c increment, for 2 hours in an inert atmosphere. the data were analyzed using model-fitting methods, testing a total of 21 models to calculate the reaction kinetics. the results revealed that weight loss increased with temperature, reaching a maximum at 18.61% (450 °c), with activation energies of 5.817–123.51 kj/mol. the d2 diffusion model best described the process (ea = 7.267 kj/mol, a = 0.022 min⁻¹). the pyrolysis index rose from 0.0113 (350 °c) to 0.051 (500 °c). at 450°c, 18.9% condensable products formed, containing alkanes, alicyclics, and aromatics (ftir/gc-ms). these findings facilitate the optimization of sustainable pyrolysis of low-rank coal for the production of valuable outputs.