Study on the catalysis of copper-based compounds on coal spontaneous combustion and its mechanism

ABSTRACT

To study the effect of the copper element in coal on the spontaneous combustion process of coal, corresponding copper-containing compounds were added to the coal-based on their occurrence state, and thermodynamic experiments and in-situ diffuse reflectance infrared spectroscopy experiments were conducted. Thermodynamic oxidation experiments have shown that the catalytic effects of Cu (NO₃)₂, CuCl₂, CuCl, and Cu₂O on three types of coal with different degrees of metamorphism are mainly reflected in the accelerated oxidation stage. After adding copper-containing compounds, the ignition temperature of coal decreased by 22.1°C to 134.4°C, the heat release increased by 1.33 to 3.19 times, and the CO emission and oxygen consumption rate also increased. CuCl has the greatest impact on the ignition point temperature of coal and increases the oxygen consumption rates of DNH and TS by 2.32 and 1.51 times that of raw coal. CuCl₂ has the strongest catalytic effect on coal oxidation heat release. Through in-situ diffuse reflectance infrared spectroscopy experiments, it was found that the reaction rate of fatty hydrocarbons in the oxidation process of three types of coal with the addition of copper-containing compounds increased to 1.3–3 times that of raw coal, and the oxidation rate of oxygen-containing functional groups also significantly increased, while the cracking temperature of aromatic structures significantly decreased. This is because copper ions, as strong free radicals, induce free radical chain reactions in coal and exhibit a strong promoting effect on the coal oxygen reaction process.

KEYWORDS:

• Copper compound
• spontaneous combustion of coal
• catalyze
• infrared spectrum
• spontaneous combustion characteristics

Acknowledgements

The authors acknowledge the funding support from Fundamental Research Program of Shanxi Province (202203021212295), School Fund of Taiyuan University of Technology (2022QN134) and Science and Technology Innovation Program of Higher Education Institutions of Shanxi Province (2022L052).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Fundamental Research Program of Shanxi Province [202203021212295]; Science and Technology Innovation Program of Higher Education Institutions of Shanxi Province [2022L052]; School Fund of Taiyuan University of Technology [2022QN134].