Abstract
To reveal the molecular structure characteristics of the caking components in coal, three coals with different ranks were treated using a new synthetic ionic liquid (i.e., [N4441][NO3]), the combination of which is based on the effect degree of different anions and cations of ionic liquids on the caking properties of the coals. Additionally, the raw and treated coals were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman. The results showed that the caking index (G) values of the coals decreased after [N4441][NO3] treatment, and the destruction degree decreased with increasing coal rank. The decrease in G is related to the removal of some species during [N4441][NO3] treatment. FTIR and Raman showed that aromatics with 3 or more rings but less than that in graphite and long-chain aliphatics were removed. XRD showed that [N4441][NO3] treatment decreased the graphitization degrees of the coals. Additionally, a mechanism of destroying the caking property of coal using [N4441][NO3] is proposed. [N4441][NO3] treatment could decrease the contents of aromatics with 3 or more rings but less than that in graphite and long-chain aliphatics. Consequently, the caking property of coal is destroyed.
REFERENCES
Han, S., Chen, H., Long, R., and Cui, X., Peak coal in China: A literature review, Resour., Conserv. Recycling, 2018, vol. 129, pp. 293–306. https://doi.org/10.1016/j.resconrec.2016.08.012
Xue, F., Li, D., Guo, Yu., Liu, X., Zhang, X., Zhou, Q., and Ma, B., Technical progress and the prospect of low-rank coal pyrolysis in China, Energy Technol., 2017, vol. 5, no. 11, pp. 1897–1907. https://doi.org/10.1002/ente.201700203
Jones, D.T. and Wheeler, R.V., XIX.—The composition of coal, J. Chem. Soc., Trans., 1914, vol. 105, pp. 140–151. https://doi.org/10.1039/ct9140500140
Fischer, F., The coking and swelling constituents of coal, Ind. Eng. Chem., 1925, vol. 17, no. 7, pp. 707–711. https://doi.org/10.1021/ie50187a025
Kopeliovich, L.V., Differences in the coking pressure of coal, Coke Chem., 2009, vol. 52, no. 1, pp. 5–8. https://doi.org/10.3103/s1068364x09010025
Taylor, G.H., Development of optical properties of coke during carbonization, Fuel, 1961, vol. 40, pp. 465–472.
Marsh, H. and Neavel, R.C., Carbonization and liquid-crystal (mesophase) development. 15. A common stage in mechanisms of coal liquefaction and of coal blends for coke making, Fuel, 1980, vol. 59, no. 7, pp. 511–513. https://doi.org/10.1016/0016-2361(80)90179-9
Li, X., Qin, Zh.-H., Bu, L.-H., Yang, Z., and Shen, Ch.-Ya., Structural analysis of functional group and mechanism investigation of caking property of coking coal, J. Fuel Chem. Technol., 2016, vol. 44, no. 4, pp. 385–393. https://doi.org/10.1016/s1872-5813(16)30019-6
Shui, H., Zheng, M., Wang, Z., and Li, X., Effect of coal soluble constituents on caking property of coal, Fuel, 2007, vol. 86, nos. 10–11, pp. 1396–1401. https://doi.org/10.1016/j.fuel.2006.11.027
Mohanty, A., Chakladar, S., Mallick, S., and Chakravarty, S., Structural characterization of coking component of an Indian coking coal, Fuel, 2019, vol. 249, pp. 411–417. https://doi.org/10.1016/j.fuel.2019.03.108
Grint, A., Mehani, S., Trewhella, M., and Crook, M.J., Role and composition of the mobile phase in coal, Fuel, 1985, vol. 64, no. 10, pp. 1355–1361. https://doi.org/10.1016/0016-2361(85)90334-5
Xu, K., Hu, S., Wang, Yi., Zhang, L., Su, S., Jiang, L., Xu, J., Ouyang, Z., and Xiang, J., Relation between char structures and formation of volatiles during the pyrolysis of Shenfu coal: Further understanding on the effects of mobile phase and fixed phase, Fuel Process. Technol., 2018, vol. 178, pp. 379–385. https://doi.org/10.1016/j.fuproc.2018.07.022
Xie, W., Stanger, R., Wall, T.F., Lucas, J.A., and Mahoney, M.R., Associations of physical, chemical with thermal changes during coking as coal heats–Experiments on coal maceral concentrates, Fuel, 2015, vol. 147, pp. 1–8. https://doi.org/10.1016/j.fuel.2015.01.016
Liu, X., Ling, Q., Zhao, Z., Xie, R., Yu, D., Ke, Q., Lei, Z., and Cui, P., Effects of low-temperature rapid pyrolysis treatment on the improvement in caking property of a Chinese sub-bituminous coal, J. Anal. Appl. Pyrolysis, 2018, vol. 135, pp. 319–326. https://doi.org/10.1016/j.jaap.2018.08.021
Liu, X., Cui, P., Ling, Q., Zhao, Z., and Xie, R., A review on co-pyrolysis of coal and oil shale to produce coke, Front. Chem. Sci. Eng., 2019, vol. 14, no. 4, pp. 504–512. https://doi.org/10.1007/s11705-019-1850-z
Liu, X., Hu, J., Xie, R., Fang, B., and Cui, P., Formation mechanism of solid product produced from co-pyrolysis of Pingdingshan lean coal with organic matter in Huadian oil shale, Front. Chem. Sci. Eng., 2020, vol. 15, no. 2, pp. 363–372. https://doi.org/10.1007/s11705-020-1944-7
Liu, X., Li, G., Zhao, H., Cheng, F., Xie, R., Zhao, Z., and Cui, P., Upgrading deashed Huadian oil shale using low-temperature pyrolysis treatment and its application in coal-blending coking, Fuel Process. Technol., 2021, vol. 223, p. 106994. https://doi.org/10.1016/j.fuproc.2021.106994
Hallett, J.P. and Welton, T., Room-temperature ionic liquids: Solvents for synthesis and catalysis. 2, Chem. Rev., 2011, vol. 111, no. 5, pp. 3508–3576. https://doi.org/10.1021/cr1003248
Bai, Z.-J., Wang, C.-P., Deng, J., Kang, F.-R., and Shu, Ch.-M., Effects of ionic liquids on the chemical structure and exothermic properties of lignite, J. Mol. Liq., 2020, vol. 309, p. 113019. https://doi.org/10.1016/j.molliq.2020.113019
Geng, S., Fan, T., and Liu, Y., Application of ionic liquid [BMIm]BF4 in swelling pretreatment of Shenhua coal, Coal Convers., 2010, vol. 33, no. 2, pp. 35–38.
Mo, W., He, X., Ma, Ya., Ma, J., Ma, Yo., Ma, F., Fan, X., and Wei, X., Effect of swelling with ionic liquid on the molecular structure and pyrolysis behavior of hefeng sub-bituminous coal, Energy Fuels, 2019, vol. 34, no. 12, pp. 16099–16108. https://doi.org/10.1021/acs.energyfuels.0c03127
Mo, W., He, X., Ma, Ya., Ma, J., Ma, Yo., Ma, F., Fan, X., and Wei, X., Effect of swelling with ionic liquid on the molecular structure and pyrolysis behavior of hefeng sub-bituminous coal, Energy Fuels, 2020, vol. 34, no. 12, pp. 16099–16108. https://doi.org/10.1021/acs.energyfuels.0c03127
Wang, Sh.-K., Wei, X.-Yo., Li, Sh., and Zong, Zh.-M., Insights into physicochemical changes of Yinggemajianfeng lignite in co-solvents of ionic liquids and methanol, Energy Fuels, 2019, vol. 33, no. 4, pp. 2867–2871. https://doi.org/10.1021/acs.energyfuels.8b03956
Ni, G., Wang, H., Nie, B., Wang, Y., Dou, H., Lu, S., and Wang, G., Research of wetting selectivity and wetting effect of imidazole ionic liquids on coal, Fuel, 2021, vol. 286, part 1, p. 119331. https://doi.org/10.1016/j.fuel.2020.119331
Ni, G., Li, Z., Sun, Q., Li, S., and Dong, K., Effects of [Bmim][Cl] ionic liquid with different concentrations on the functional groups and wettability of coal, Adv. Powder Technol., 2019, vol. 30, no. 3, pp. 610–624. https://doi.org/10.1016/j.apt.2018.12.008
Lu, L., Sahajwalla, V., and Harris, D., Characteristics of chars prepared from various pulverized coals at different temperatures using drop-tube furnace, Energy Fuels, 2000, vol. 14, no. 4, pp. 869–876. https://doi.org/10.1021/ef990236s
Qiu, S., Zhang, S., Suo, G., Qiu, G., Yin, C., Li, Ya., Hu, M., Xiao, X., and Wen, L., Effects of Fe2O3 addition on the thermoplasticity and structure of coking coal matrix during thermoplastic stage of pyrolysis, Fuel, 2020, vol. 260, p. 116305. https://doi.org/10.1016/j.fuel.2019.116305
Guo, S., Geng, W., Yuan, S., Yi, C., Dong, Z., and Xu, J., Understanding the molecular structure of Datong coal by combining experimental and computational study, J. Mol. Struct., 2023, vol. 1279, p. 135035. https://doi.org/10.1016/j.molstruc.2023.135035
Amer, M.W., Alhesan, J.S.A., Gengenbach, T., Marshall, M., Fei, Yi., Jackson, W.R., and Chaffee, A.L., Structural characteristics of low-aromaticity marine and lacustrine oil shales and their NaOH-HCl kerogens determined using 13C NMR and XPS, Aust. J. Chem., 2020, vol. 73, no. 12, pp. 1237–1249. https://doi.org/10.1071/ch20168
Lu, J., Wang, X., Li, H., Shi, S., Yang, W., Lu, Yi., Shao, S., and Ye, Q., Molecular insights into the methane adsorption capacity of coal under microwave irradiation based on solid-state 13C-NMR and XPS, Fuel, 2023, vol. 339, p. 127484. https://doi.org/10.1016/j.fuel.2023.127484
Xu, J., Tang, H., Su, S., Liu, J., Xu, K., Qian, K., Wang, Yi., Zhou, Yi., Hu, S., Zhang, A., and Xiang, J., A study of the relationships between coal structures and combustion characteristics: The insights from micro-Raman spectroscopy based on 32 kinds of Chinese coals, Appl. Energy, 2018, vol. 212, pp. 46–56. https://doi.org/10.1016/j.apenergy.2017.11.094
Liu, X., You, J., Wang, Yu., Lu, L., Xie, Yi., Yu, I., and Fu, Q., Raman spectroscopic study on the pyrolysis of Australian bituminous coal, J. Fuel Chem. Technol., 2013, vol. 42, no. 3, pp. 270–276. https://doi.org/10.1016/s1872-5813(14)60019-0
Liu, X., Li, G., Zhao, H., Ye, Yo., Xie, R., Zhao, Z., Lei, Z., and Cui, P., Changes in caking properties of caking bituminous coals during low-temperature pyrolysis process, Fuel, 2022, vol. 321, p. 124023. https://doi.org/10.1016/j.fuel.2022.124023
Wang, S., Song, H., Bai, S., Ye, Yo., Xie, R., Zhao, Z., Liu, X., and Cui, P., Mechanism of destruction of caking property of a coking coal using low-temperature pyrolysis treatment, J. Anal. Appl. Pyrolysis, 2022, vol. 168, p. 105764. https://doi.org/10.1016/j.jaap.2022.105764
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This work was supported by the National Natural Science Foundation of China (grant nos. 22308006 and 22278001), the Natural Science Foundation of Anhui Provincial Education Department (no. KJ2021A0407), the Natural Science Foundation of Anhui Province (grant no. 2008085QB87), and Anhui Provincial Postdoctoral Science Foundation (no. 2021B538).
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Yuan Fang, Han, K., Chen, Y. et al. Effects of a New Synthetic Ionic Liquid on Caking Properties of Coals with Three Different Ranks. Coke Chem. 67, 61–71 (2024). https://doi.org/10.3103/S1068364X2460012X
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DOI: https://doi.org/10.3103/S1068364X2460012X