Microscopic analysis of the differential low-temperature oxidation ability of coal

Coal oxidation ability is a key factor in spontaneous combustion, necessitating a microscopic analysis of oxidation differences through both experimental and quantum chemical simulations. This study selected two coal samples from different mining faces in the same area, which exhibited the most significant differences in oxidation ability. Low-temperature liquid nitrogen adsorption experiments revealed the pore structure of these samples. Molecular models were constructed based on the experimental analysis, and quantum chemistry simulations were performed to examine the physical and chemical adsorption mechanisms of O2 and the reaction mechanism leading to ·OH formation. The results showed that the lipid and pyridine groups in coal samples No. 1 and No. 2 were more prone to physical adsorption of O2. Although the surface area and pore volume of coal sample No. 1 were higher than those of coal sample No. 2, the latter exhibited a stronger physical adsorption of O2. The activation energies for the chemical adsorption of active H and O2 in coal sample No. 2 were low and thus facilitated chemical adsorption. The coal–oxygen chemical adsorption capacity influenced the generation of ·OH, with coal sample No. 2 reacting more readily with O2, thus increasing the oxidation rate.