Dissect the capacity of low-temperature oxidation of coal with different metamorphic degrees

Radical chemistry is a major factor affecting the low-temperature oxidation of coal, which plays a critical role in the coal oxygen complex reaction. However, the characteristics of radical for judging its ability to oxidize are still poorly understood. The electron paramagnetic resonance (EPR) spectroscopy has emerged as a powerful approach in studying the behavior of radicals. So the EPR spectra of coal low-temperature oxidation were investigated by in-situ EPR spectroscopy. Analysis of the initial temperature of CO evolution and its increment and crossing-point temperatures (CPTs) of coal reveal that the oxidizability of low-rank coal is more prominent than others. The EPR linear profile of low-rank coal has a well temperature dependence and a large g factor, an indicator of oxidizability. However, it is not consistent with the increasing trend of the absolute content of radical concentration. This study provides a novel approach to quantify the oxidizability of coal using the relative growth rate R of radials, and the results are consistent with the coal spontaneous combustion tendency. The main objective of the current study is to obtain a comprehensive understanding of low-temperature oxidation of coal with different ranks.

Automated summary

Radical chemistry is a major factor in the low-temperature oxidation of coal, with electron paramagnetic resonance (EPR) spectroscopy being a powerful tool to study the behavior of radicals. The study found that low-rank coal has a more prominent oxidizability compared to other types of coal, and a novel approach using the relative growth rate R of radicals was developed to quantify the oxidizability of coal. These results are consistent with the tendency of coal spontaneous combustion.