Kinetic and thermodynamic analysis of tar‐rich coal pyrolysis: Comparison between model‐free and model‐fitting methods

Abstract The pyrolysis of tar‐rich coal plays a critical role in the efficient utilization of energy and the production of chemicals. This study presents a comprehensive kinetic and thermodynamic analysis of Xinjiang tar‐rich coal pyrolysis, employing both model‐free and model‐fitting approaches. The results reveal that the dominant pyrolysis mechanism transitions with temperature, and the activation energy reaches its minimum at α = 0.4, highlighting the multi‐step nature of the process. The model‐free method provides higher activation energy values, offering a more accurate depiction of the intrinsic kinetics. Thermodynamic analysis indicates that the pyrolysis reaction is endothermic (Δ H > 230 kJ/mol), with a significant rise in enthalpy to 298.80 kJ/mol at higher temperatures ( α = 0.7), likely due to intense depolymerization of coal's molecular structure. Δ S is consistently negative (−283.26 to −266.19 J/(mol·K)) and decreases in magnitude with increasing conversion, reflecting a reduction in system disorder, likely due to graphitization and volatile loss. Δ G remains positive (427–488 kJ/mol), confirming that the reaction is non‐spontaneous and requires continuous external heating. These findings provide valuable insights for enhancing tar yield and optimizing operational conditions in both industrial and in‐situ pyrolysis processes.