Hydrogen Abstraction Reaction Mechanism of Oil-Rich Coal Spontaneous Combustion

Oil-rich coal is a type of coal with a hydrogen-rich structure, making it inclined to spontaneous combustion at low temperatures. In investigating the procedure of hydrogen production through the low-temperature oxidation of oil-rich coal, Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR) experiments were conducted, along with quantum chemical simulations, to identify dynamic changes in functional groups during the low-temperature oxidation. The experimental results indicate that oil-rich coal primarily comprises hydrogen-containing structures such as aromatic hydrocarbons and aldehyde groups. On the basis of the observed patterns of functional group changes, three stages of hydrogen generation during the low-temperature oxidation of oil-rich coal were deduced. Furthermore, quantum chemical simulations were employed to model the structural changes of target functional groups during the low-temperature oxidation of oil-rich coal. Combining the results of experiments and simulation calculations revealed the primary mechanism behind the low-temperature oxidation of oil-rich coal leading to hydrogen production. The study identified the reaction of methyl-methylene side chains forming aldehyde groups as the precursor to hydrogen. Simultaneous oxidation and structural interactions eventually result in hydrogen formation. These findings contribute to a more profound insight into the mechanism behind the spontaneous combustion of coal oxidation and present a theoretical foundation for the development of effective avoidance and management technologies for the spontaneous combustion of oil-rich coal.