Effect of Acidification Pretreatment on the Composition and Structure of Soluble Organic Matter in Coking Coal
WANG Fang-fang1, ZHANG Xiao-dong1, 2*, PING Xiao-duo1, ZHANG Shuo1, LIU Xiao1, 2
1. School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China
2. Department of Geology and Surveying and Mapping Engineering, Shanxi University of Energy, Jinzhong 030600, China
Abstract：In order to explore the influence of acidification pretreatment on the extractable composition and macromolecular structure of coal, Gujiao coking coal in Shanxi Province was acidified and demineralized by HCl and HF, and different concentrations of tetrahydrofuran (THF) were selected for solvent extraction experiments of raw coal (RC) and acidified coal (DC). The extraction of raw coal and acidified coal were compared and analyzed using modern technical means such as GC-MS and FTIR. The results show that with the increase of solvent concentration, the extraction rate of raw coal and acidified coal tends to increase. After acidification, the minerals in coal decrease significantly, the solvent permeability increases, and the extraction rate increases. However, acidification pretreatment has no noticeable effect on the extraction rate of high-concentration THF because high-concentration THF solvent can extract dissoluble components from coking coal to a large extent, and acidification pretreatment has a relatively weak promotion effect on dissoluble components. Therefore, with the increase of solvent concentration, raw coal and acidified coal have no apparent effect. After acidification pretreatment, the value of the hydrogen-rich degree parameter (I1) of coal samples decreased significantly, which was 0.61 less than raw coal. With the increase of THF concentration, the I1 value of raw coal decreased first and then increased, while the I1 value of acidified coal increased first and then decreased, showing opposite trends. The aromatization degree parameter (I2) and oxygen enrichment degree parameter (I3) increase obviously, in which I2 value is twice that of raw coal, I3 value is 11.82, almost three times that of raw coal, and after THF extracts raw coal with different concentrations, the oxygen index I3 value increases first and then decreases, while acidified coal decreases. The fat structure parameter (I4) is obviously reduced, which is only 8% of the raw coal, and the I4 value of its raffinate is far lower than that of the raw coal raffinate. The relative content of heteroatom compounds in acidified coal extract is significantly reduced by 83.14%~89.64%, and the relative content of aliphatic hydrocarbons is significantly increased, which is 5~26 times of that in raw coal extract, mainly including straight-chain hydrocarbons such as eicosane, docosane and triacontane, among which C19—C23 accounts for 79.17% of the total components of the extract. Aromatic substances are not found in extracts and only in 100%THF extracts in raw coal, with little change in relative content. It is considered that acidification pretreatment greatly influences the fat structure and oxygen-containing compounds in coal but has a relatively small influence on the aromatic structure.
王芳芳，张小东，平晓朵，张 硕，刘 晓. 酸化预处理对焦煤可溶有机质组成和结构的影响[J]. 光谱学与光谱分析, 2022, 42(03): 896-903.
WANG Fang-fang, ZHANG Xiao-dong, PING Xiao-duo, ZHANG Shuo, LIU Xiao. Effect of Acidification Pretreatment on the Composition and Structure of Soluble Organic Matter in Coking Coal. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(03): 896-903.
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