Effect of solvent swelling with different enhancement methods on the microstructure and pyrolysis performance of Hefeng subbituminous coal

Kan, Haidong; Wang, Yue; Mo, Wen‐Long; Wei, Xian‐Yong; Mi, Hongyu; Ma, Kong-Jun; Zhu, Min; Guo, Wen-Cang; Guo, Jia; Niu, Jun-Min; Fan, Xing

doi:10.1016/j.fuel.2022.126066

Cited by 12 publications

(7 citation statements)

References 42 publications

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“…The ratio of the absorption peak areas of −CH 2 to −CH 3 can reflect the relative content of organic structures, denoted as the aliphatic structure parameter

[ 22 , 23 ]. The values for NL (3.71) and NL CH-R (1.53) are higher than those for NL BE-R (0.53) and NL EA-R (0.69), indicating that aliphatic hydrocarbons in NL and NL CH-R mainly exist in long-chain forms with fewer side-chain aliphatic hydrocarbons.…”

Section: Resultsmentioning

confidence: 99%

“…The asymmetric −CH2 and symmetric −CH2 absorption peaks at 2930-2900 cm −1 and 2870-2810 cm −1 are relatively high in all samples, with contents above 20% (except for NLBE-R). ) 3000 3100 3200 3300 3400 3500 3600 3000 3100 3200 3300 3400 3500 3600 3000 3100 3200 3300 3400 3500 3600 3000 3100 3200 3300 3400 3500 3600 The ratio of the absorption peak areas of −CH 2 to −CH 3 can reflect the relative content of organic structures, denoted as the aliphatic structure parameter S = A(CH 2 )/A(CH 3 ) [22,23]. The values for NL (3.71) and NL CH-R (1.53) are higher than those for NL BE-R (0.53) and NL EA-R (0.69), indicating that aliphatic hydrocarbons in NL and NL CH-R mainly exist in long-chain forms with fewer side-chain aliphatic hydrocarbons.…”

Section: Changes In Functional Groups Of Insoluble Portionsmentioning

confidence: 99%

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Composition Distribution of the Thermal Soluble Organics from Naomaohu Lignite and Structural Characteristics of the Corresponding Insoluble Portions

Zhu,

Ma,

et al. 2024

Molecules

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With cyclohexane (CH), benzene (BE), and ethyl acetate (EA) as solvents, Naomaohu lignite (NL, a typical oil-rich, low-rank coal) from Hami, Xinjiang, was thermally dissolved (TD) to obtain three types of soluble organics (NLCH, NLBE, and NLEA) and the corresponding insoluble portions (NLCH-R, NLBE-R, and NLEA-R). Ultimate analysis, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG), and gas chromatography–mass spectrometry (GC/MS) were used to characterize NL and its soluble and insoluble portions. Results showed that, compared with NL, the C element in NLCH-R, NLBE-R, and NLEA-R increased, while the O element decreased significantly, indicating that thermal dissolution is a carbon enrichment process and an effective deoxidation method. The GC/MS results showed that oxygen-containing organic compounds (OCOCs) are dominant in NLCH, NLBE, and NLEA. NLCH is mainly composed of ketones (11.90%) and esters (19.04%), while NLBE and NLEA are composed of alcohols (12.18% and 2.42%, respectively) and esters (66.09% and 84.08%, respectively), with alkyl and aromatic acid esters as the main components. Among them, EA exhibits significant selective destruction for oxygen-containing functional groups in NL. XPS, FTIR, and TG-DTG results showed that thermal dissolution can not only affect the macromolecular network structure of NL, but also improve its pyrolysis reactivity. In short, thermal dissolution can effectively obtain oxygen-containing organic compounds from NL.

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“…The ratio of the absorption peak areas of −CH 2 to −CH 3 can reflect the relative content of organic structures, denoted as the aliphatic structure parameter

Section: Resultsmentioning

confidence: 99%

Section: Changes In Functional Groups Of Insoluble Portionsmentioning

confidence: 99%

Composition Distribution of the Thermal Soluble Organics from Naomaohu Lignite and Structural Characteristics of the Corresponding Insoluble Portions

Zhu,

Ma,

et al. 2024

Molecules

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“…Therefore, both inhibitors can effectively plug the pores in coal, and it is observed that the effect of biological inhibition using Bacillus pasteuris is more obvious than that of chemical inhibition. The nuclear magnetic resonance detection of coal samples can effectively determine the structure information of organic matter [37], and nuclear magnetic resonance technology is used to detect lignite coal samples. Based on the analysis of detection results, we observed five distinct carbon signals in the lignite, which can be fitted via the Origin2019 software to better understand the structural characteristics of lignite.…”

Section: Pore Structure Characteristic Parameter Analysismentioning

confidence: 99%

Experimental Study on the Microstructural Characterization of Retardation Capacity of Microbial Inhibitors to Spontaneous Lignite Combustion

Wang,

Liu,

Chen

et al. 2023

Fire

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Mine fires are one of the common major disasters in underground mining. In addition to the external fire sources generated by mining equipment and mechanical and electrical equipment during operations, coal is exposed to air during mining, and spontaneous combustion is also the main cause of mine fires. In order to reduce the hidden danger of coal mines caused by spontaneous coal combustion during lignite mining, the microbial inhibition of coal spontaneous combustion is proposed in this paper. Via SEM, pore size analysis, and NMR and FT-IR experiments, the mechanism of coal spontaneous combustion is discussed and revealed. The modification of lignite before and after the addition of retardants is analyzed from the perspective of microstructure, and the change in flame retardancy of the lignite treated with two retardants compared with raw coal is explored. The results show that, compared with raw coal, a large number of calcium carbonate particles are attached to the surface of the coal sample after bioinhibition treatment, and the total pore volume and specific surface area of the coal sample after bioinhibition treatment are decreased by 68.49% and 74.01%, respectively, indicating that bioinhibition can effectively plug the primary pores. The results of NMR and Fourier infrared spectroscopy show that the chemical structure of the coal sample is mainly composed of aromatic carbon, followed by fatty carbon and carbonyl carbon. In addition, the contents of active groups (hydroxyl, carboxyl, and methyl/methylene) in lignite after bioretardation are lower than those in raw coal, and methyl/methylene content is decreased by 96.5%. The comparison shows that the flame-retardant performance of biological retardants is better than that of chemical retardants, which provides an effective solution for the efficient prevention and control of spontaneous combustion disasters in coal mines.

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“…Lignite is composed of similar but not identical molecular structures that are highly cross-linked in three dimensions-a network of "basic structure unit", mainly benzene rings and naphthalene rings connected by bridge bonds [1,2]. There are also many small compounds in coal, mostly derived from the original components of coal-forming plants, which are mainly associated by noncovalent bonds, such as hydrogen bonds, van der Waals force, and π-π interaction, and dispersed in the macromolecular network structure of coal.…”

Section: Introductionmentioning

confidence: 99%

Effect of Solvent Pretreatment on the Flash Pyrolysis Performance of Yinggema Lignite

Mo,

Kan,

et al. 2023

Sustainability

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Yinggema lignite (YL) was pretreated with isometric acetone/carbon disulfide mixed solvent to obtain the residue (RYL) and, then, RYL was separated by density difference with carbon tetrachloride to obtain the light residue (LRYL). The flash pyrolysis performances of YL and LRYL were analyzed by thermogravimetry–Fourier transform infrared spectrometer–Gas chromatography/mass spectrometer (TG-FTIR-GC/MS). The results showed that solvent pretreatment could remove some small molecules in the coal and swell the used coal, leading to the increase in pyrolysis reactivity. The intensity and absorption peak area of C=O from LRYL were significantly reduced compared to YL, resulting from the high hydrogen-donating ability of acetone. The main gaseous products of both samples are H2O, CH4, CO2, and CO; the hydrocarbons detected by GC/MS in the pyrolysis products of YL and LRYL at 450 °C were mainly alkanes, alkenes, and arenes, with the higher relative contents of alkanes of 31.1% and 36.2%, followed by arenes of 27.1% and 22.6%, respectively. The oxygen-containing compounds were mainly alcohols and phenols. It is speculated that the pretreated coal could expose more oxygen-containing functional groups, facilitating their conversion to phenolic hydroxyl groups during the pyrolysis process, resulting in more phenolic compounds.

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Effect of solvent swelling with different enhancement methods on the microstructure and pyrolysis performance of Hefeng subbituminous coal

Cited by 12 publications

References 42 publications

Composition Distribution of the Thermal Soluble Organics from Naomaohu Lignite and Structural Characteristics of the Corresponding Insoluble Portions

Composition Distribution of the Thermal Soluble Organics from Naomaohu Lignite and Structural Characteristics of the Corresponding Insoluble Portions

Experimental Study on the Microstructural Characterization of Retardation Capacity of Microbial Inhibitors to Spontaneous Lignite Combustion

Effect of Solvent Pretreatment on the Flash Pyrolysis Performance of Yinggema Lignite

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