Pore structure reconstruction of residual coal under different pyrolysis modes and its influence on subsequent oxidation thermal behavior and stage kinetics

This study systematically investigated the influence of pyrolysis mode on the subsequent oxidation behavior of residual coal. Thermogravimetric analysis, pore structure characterization, and staged kinetic analysis were employed to compare natural and steam pyrolysis. A critical pore reconstruction point was identified at 600 °C, where NP600 achieved a maximum pore volume of 0.8490 cm 3 /g. High-temperature pyrolysis increased pore heterogeneity, causing mechanism-function mismatch in the coal–oxygen adsorption stage. Characteristic temperatures T ₃, T ₄, and T ₅ correlated strongly with oxidation reactivity, while staged activation energies successfully predicted minimum spontaneous combustion periods, increasing from 31.06 d for SP100 to 468.58 d for SP800. These results indicate that pyrolysis-mode-induced pore structure reconstruction is a key factor governing residual coal oxidation and stage-dependent kinetics under controlled laboratory conditions, providing quantitative guidance for comparative reactivity evaluation and safe post-conversion handling.