On the difference of graphitization behavior between vitrinite- and inertinite-rich anthracites during heat treatment

Wang, Lu; Qin, Rongfang; Liu, Yu; Zhang, Hao

doi:10.1080/15567036.2019.1656681

Cited by 6 publications

(3 citation statements)

References 58 publications

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“…The experimental results of thermal simulation samples are shown in Table S1. According to the research results of predecessors and our research group, it is difficult for the sample to reach a high degree of graphitization by heating without the catalytic action of additives. − …”

Section: Experimental Resultsmentioning

confidence: 99%

Impact of Graphitization Degree on the Electrochemical and Thermal Properties of Coal

Xu,

Cao,

Wei

et al. 2024

ACS Omega

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Coal-based cryptocrystalline graphite is an intermediate phase formed during the transformation of highly metamorphic anthracite into crystalline graphite. In order to explore the relationship between the graphitization degree of coal-based cryptocrystalline graphite and its physical properties from macromolecular structure to provide a theoretical basis for industrial application, samples were tested by X-ray diffraction, electrochemistry, and thermal conductivity and compared with standard graphite (SG) and artificial thermal simulation graphitized samples. The results show that with the increase of graphitization degree and the growth of microcrystalline structure, the electrical impedance of cryptocrystalline graphite decreases, the conductivity increases, the specific capacity of initial discharge increases, and the thermal conductivity increases, which gradually approach the electrical and thermal properties of crystalline graphite. The linear equations between impedance and L a and L c are y = −0.42x + 70.44 and y = −1.87x + 70.62, and the correlation coefficients are 0.93 and 0.88. The linear equations between thermal conductivity and the horizontal extension length (L a ) and vertical stacking thickness (L c ) are y = 0.09x + 1.36 and y = 0.4x + 0.76, the correlation coefficients are 0.82 and 0.84., and the reduction of microcrystalline parameters d 002 and the increase of L a and L c lead to a direct improvement of physical properties. Artificial thermal simulation samples also show the same regularity, but their physical properties are lower than those of natural evolution samples. Short-term high-temperature simulation is different from long-term magma heat and pressure, and the growth of graphite microcrystals is more complete under long-term geological conditions, resulting in better physical properties.

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Section: Experimental Resultsmentioning

confidence: 99%

Impact of Graphitization Degree on the Electrochemical and Thermal Properties of Coal

Xu,

Cao,

Wei

et al. 2024

ACS Omega

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“…The fact is that not all anthracites, even those of similar ranks, exhibit the same level of graphitization when heated under the same circumstances [15]. This is mainly related to the organic characteristics of anthracite, such as its microstructure, elemental composition, coalification degree, etc., [6,7,10,12,13,[16][17][18][19][20][21][22][23][24][25][26]. Coal itself is a complex geological substance, and it also contains varying proportions of minerals in addition to the main organic matter of the coal body.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Mineral Catalytic Graphitization of Anthracite during Series High Temperature Treatment

Cao,

Li,

Zhang

et al. 2023

Minerals

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Graphite can be artificially converted from anthracites under high temperatures; however, the exact mechanism through which inorganic minerals contribute to the graphitization process is still unknown. In light of this, several selected minerals in different amounts were added to demineralized anthracite coal. The anthracite–mineral mixtures were subjected to artificial graphitization experiments under temperatures ranging from 1700 to 2900 °C in the laboratory. The obtained series of coal-based graphites with various levels of graphitization were characterized by X-ray diffraction (XRD), and the derived structural parameters, such as d002 and FWHM (002), La, and Lc were used to compare the carbon structural evolution during the high temperature treatment and mineral catalytic graphitization. Moreover, the amorphous carbon of anthracite is eventually transformed into the highly ordered crystalline carbon of coal-based graphite. The five added minerals show interesting structural variation during the graphitization process, in which pyrite is decomposed into iron (Fe), illite, quartz, and kaolinite, which can react with disordered carbon in organic matter to form moissanite (SiC), while dolomite seems to react with sulfur to form oldhamite (CaS). At temperatures less than 2300 °C, the minerals could significantly enhance the catalytic effect. There is a clear difference in the catalytic effect of different minerals on graphitization. Kaolinite exhibits the strongest catalytic effect. The minerals dolomite, illite, and quartz only show a certain degree of catalysis. Pyrite, however, only has a limited effect on improving the degree of graphitization at a temperature of 1700 °C. However, once the temperature exceeds 2300 °C, the dominant factor controlling the graphitization of anthracite appears to be the temperature. According to the growth pattern at microcrystalline sizes (La and Lc), the minerals’ catalytic effects can be classified into three groups. The first group includes minerals that preferentially promote La growth, such as pyrite, illite, and quartz. The second group includes minerals that preferentially promote Lc growth, such as dolomite. Finally, kaolinite is in a separate group that promotes microcrystal growth in both the lateral and vertical directions simultaneously. The mechanisms of the minerals’ catalytic graphitization are discussed in this paper. The promotion role of minerals in the artificial graphitization process may help to optimize the graphitization process and reduce the process cost in the future.

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“…Zhang (2014) conducted high-temperature treatment at 2,500 °C on inertinite-rich samples and vitrinite-rich samples, and found that the graphitization degree of inertinite was higher. The artificial thermal simulation comparison experiment conducted by Wang et al (2019) between vitrinite and inertinite showed that the required graphitization temperature for inertinite was higher, vitrinite has higher graphitization ability than inertinite. Through the study of natural graphitized coal samples, Li et al (2021) (Li, 2022), believes that the graphitization ability of liptinite is the highest, followed by vitrinite, and inertinite always shows inertness.…”

Section: Introductionmentioning

confidence: 99%

High-temperature graphitization characteristics of vitrinite and inertinite

Zhifei,

Daiyong,

Gaojian

et al. 2023

Front. Earth Sci.

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In order to explore the graphitization characteristic differences between vitrinite and inertinite in coal, this study conducted high-temperature thermal simulation experiments (at five temperature points: 1800°C, 2100°C, 2400°C, 2700°C, and 3000°C) using inertinite-rich and vitrinite-rich samples as graphitization precursors. The quantitative comparison for the evolution characteristics of their graphite lattice was carried out using high-resolution transmission electron microscopy (HRTEM), X-ray diffractometer (XRD), and Raman spectroscopy (Raman) techniques. HRTEM revealed that an evident increase in carbon layer numbers and degree of extension was observed with increasing treatment temperature, XRD showed the variation of lattice parameters (d002/La/Lc) with temperature, Raman data revealed the variation of lattice defects (R2/R3) with temperature. It was discussed about the differences of graphite lattice construction processes between inertinite and vitrinite, throughout the entire temperature range of the experiment, the d002 spacing of inertinite was always smaller than that of vitrinite, indicating a higher degree of graphitization. vitrinite exhibited a uniform and smooth evolution state throughout the entire heating process, while inertinite exhibited an “inert” state between 1800°C and 2100°C (d002 values stagnated near at 0.3440 nm). With increasing simulated temperature, the defect level (R2 and R3) of vitrinite rapidly decreased below that of inertinite, throughout the entire temperature range, vitrinite demonstrated superior defect healing ability in terms of both rate and capability compared to inertinite. Under high-temperature thermal simulation, the three-dimensional lattice construction and defect elimination of vitrinite exhibited synchronous evolution characteristics. On the other hand, the formation of the graphite lattice in inertinite showed an evolutionary trend of “first three-dimensional lattice construction, followed by gradual defect elimination”.

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On the difference of graphitization behavior between vitrinite- and inertinite-rich anthracites during heat treatment

Cited by 6 publications

References 58 publications

Impact of Graphitization Degree on the Electrochemical and Thermal Properties of Coal

Impact of Graphitization Degree on the Electrochemical and Thermal Properties of Coal

Investigation on the Mineral Catalytic Graphitization of Anthracite during Series High Temperature Treatment

High-temperature graphitization characteristics of vitrinite and inertinite

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