Reaction mechanisms involving peroxy radical in the low-temperature oxidation of coal

Xi, Zhilin; Jin, BangXin; Shan, Ze

doi:10.1016/j.fuel.2021.120943

Cited by 38 publications

(16 citation statements)

References 46 publications

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“…According to the Δ E of all reactions, the reaction sequences can be inferred, that is, they gradually occur from small to large. According to previous experimental analyses, ,, when Δ E = 0, the reaction can occur spontaneously. When Δ E < 40 kJ/mol, the reaction can occur at room temperature and pressure ( T < 30 °C).…”

Section: Inference Of Chain Reactions Of Coal Spontaneous Combustionsupporting

confidence: 79%

Quantum Chemistry Calculation Study on Chain Reaction Mechanisms and Thermodynamic Characteristics of Coal Spontaneous Combustion at Low Temperatures

Huo

Zhu

et al. 2021

ACS Omega

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The coal spontaneous combustion phenomenon seriously affects the safety production of coal mines. Aiming at the problem of complex coal molecular structure and incomplete reaction sequences at present, the mechanisms and thermodynamic parameters of coal spontaneous combustion chain reactions were explored by combining experimental detections and molecular simulations. First, the active groups on the surface of coal were obtained by Fourier transform infrared spectroscopy (FTIR), mainly including methyl (−CH3), methylene (−CH2), methyne (−CH), phenolic hydroxyl (−ArOH), alcohol hydroxyl (−ROH), carboxyl (−COOH), aldehyde (−CHO), and ether (−O−), and the coal molecular models containing functional groups and radicals were established. According to the charge density, electrostatic potential, and frontier orbital theories, the active sites and active bonds were obtained, and a series of reactions were given. The thermodynamic and structural parameters of each reaction were explored. In the chain initiation reaction stage, O2 chemisorption and the self-reaction of radicals play a leading role. In this stage, heat gradually accumulates and various radicals begin to generate, where the intramolecular hydrogen transfer reaction of a peroxide radical (−C–O–O·) can produce the key hydroxyl radical (−O·). In the chain propagation reaction stage, O2 and −O· continuously consume active sites to accelerate the reaction sequences and increase the temperature of coal, and index gases such as CO and CO2 generate, causing the chain cycle reactions to gradually form. The chain termination reaction stage is the formation of stable compounds such as ethers, esters, and quinones, which can inhibit the development of chain reactions. The results can further explain the reaction mechanism of coal spontaneous combustion and provide references for the development and utilization of chemical inhibitors.

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Section: Inference Of Chain Reactions Of Coal Spontaneous Combustionsupporting

confidence: 79%

Quantum Chemistry Calculation Study on Chain Reaction Mechanisms and Thermodynamic Characteristics of Coal Spontaneous Combustion at Low Temperatures

Huo

Zhu

et al. 2021

ACS Omega

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“…It can be assumed that the coal was free in the process of oxidation and heating. 36 As the temperature increased, the radical reaction rate increased. The free radical concentration values of the three coal samples increased as the temperature rose from room temperature to 190 °C: Hailar lignite 329.557 × 10 16 /g, Yangquan anthracite 31.867 × 10 16 /g, and Panjiang bituminous coal 20.485 × 10 16 /g.…”

Section: Resultsmentioning

confidence: 99%

“…The covalent bonds in the macromolecules were broken and a large number of free radicals were generated. It can be assumed that the coal was free in the process of oxidation and heating . As the temperature increased, the radical reaction rate increased.…”

Section: Resultsmentioning

confidence: 99%

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Influence of Temperature Change on the Change Law of Free Radicals in Coal

et al. 2021

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This study investigates changes in the concentration and types of free radicals in the process of coal heating, first rising and then falling. Hailar lignite, Panjiang bituminous coal, and Yangquan anthracite were selected as coal test samples. The results show that the lignite’s concentration of free radical changes during heating is greater than that of bituminous coal or anthracite. It clearly shows that lignite is more prone to spontaneous combustion. In the heating and cooling portion of the experiment, the concentration of free radicals during the cooling process was much more than that of free radicals at the same temperature during the heating process. These results obtained from this research study can provide a reference for the prevention and control of the spontaneous combustion of coal with changes in temperature. This study provides a theoretical basis for the prevention and control of spontaneous combustion of coal and the selection of retarding agents and methods in the process of flame retarding by testing the free radical changes of coal at different temperatures. Also, it provides a reference for preventing and controlling coal oxidation with the change in temperature, first rising and then falling.

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“…Chemical inhibitors are predominantly antioxidants, which can be divided into free radical scavengers, hydroperoxide decomposers, free radical quenchers, metal chelating agents, and so forth . Their mechanism is to inert reactive free radicals, which can fundamentally inhibit the COLT. ,, Li et al proposed 2,2,6,6-tetramethyl-1-piperidine-noxyl (TEMPO), butylated hydroxytoluene, VC, triphenyl phosphite, edetic acid, and phytic acid as new inhibitors from the perspective of inhibiting chain reactions, which showed that they all have certain inhibiting effects and TEMPO had the best inhibiting effects . Lu et al investigated the inhibiting properties of environment-friendly dl -malic acid on lignite and bituminous coal.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Quantum Chemical Study on the Inhibition Characteristics of Glutathione to Coal Oxidation at Low Temperature

Huo

Zhu

2022

ACS Omega

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In response to the frequent occurrence of coal spontaneous combustion accidents, this paper proposes to use glutathione (GSH) as an inhibitor to inhibit the coal oxidation at low temperature. Based on the gas production of oxidation, thermogravimetric analysis, electron spin resonance, and in situ Fourier infrared transform spectroscopy experiments, it is known that GSH has a good inhibiting effect on lignite, long-flame coal, and fatty coal. The optimal action temperature of GSH is 60–150 °C, which can effectively slow down the weight loss and exothermic process and reduce the gas production of CO and CO 2 . Compared with the raw coal, the GSH-treated coal samples possess higher crossing point temperature and lower reactive group content. Subsequently, quantum chemical calculations are performed using density functional theory. The results demonstrate that the inhibiting mechanism of GSH is inerting the reactive radicals in coal and converting them into more stable compounds. Meanwhile, the activation energy of the reaction between GSH and each reactive radical is small, and all of them can occur at room temperature and pressure. This study lays the groundwork for future development of inhibitors.

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Reaction mechanisms involving peroxy radical in the low-temperature oxidation of coal

Cited by 38 publications

References 46 publications

Quantum Chemistry Calculation Study on Chain Reaction Mechanisms and Thermodynamic Characteristics of Coal Spontaneous Combustion at Low Temperatures

Quantum Chemistry Calculation Study on Chain Reaction Mechanisms and Thermodynamic Characteristics of Coal Spontaneous Combustion at Low Temperatures

Influence of Temperature Change on the Change Law of Free Radicals in Coal

Experimental and Quantum Chemical Study on the Inhibition Characteristics of Glutathione to Coal Oxidation at Low Temperature

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