Mechanism Of Molecular Hydrogen Emission During Low Temperature Oxidation of Coal By TGA/DSC

Coals are one of the major sources for environmental problems occurring worldwide (mainly the carbon footprint when utilized as fuel) and an ultimate risk in the coal industry as explosions occurring in confined spaces of coal (like mines).

The common reasons for explosions can stem from 3 sources: either from accumulation of methane or carbon monoxide gasses above the LEL (Lower Explosion Limit) or from high concentrations of fine coal dust accumulation in the mine atmosphere.

However, still unexplained explosions in underground coal mines do occur. We have found that molecular hydrogen is also released during the self-heating process of bituminous coals during Low Temperature Oxidation (LTO), accompanied by the release of toxic and flammable gasses, under long term storage and this could be the source of these explosions. This process can occur also when the coal is stored in bunkers or under open air (in store yards of power plants or near coal mines).

A mechanism has been suggested to the emission process of the hydrogen.

In this study it is shown that the combined TGA/DSC unit can be used as a new and unique technique in corroborating and elucidation the suggested mechanism. It sheds on the suggested mechanism of the hydrogen

emission and prove that the reaction occurs via production of an unstable cyclic intermediate, the dioxirane and this is a process that should be inhibited. Also, energetic details and kinetic parameters (like temperature effects) are produced via the thermal units that might help in determining new insights into new modes to reduce the risks from explosions in underground coal mines.