酸化预处理对焦煤可溶有机质组成和结构的影响

为了探究酸化预处理对煤的可抽提物组成及大分子结构的影响,采用HCl、HF对山西古交焦煤进行酸化脱矿物处理,并选取不同浓度的四氢呋喃(T H F)对原煤(RC)及酸化煤(DC)进行溶剂抽提实验,借助色谱-质谱(GC-MS)、傅里叶红外光谱(FTIR)等现代技术手段,对比分析了原煤、酸化煤的抽提物组成及抽余物的主要官能团和...

Effect of Acidification Pretreatment on the Composition and Structure of Soluble Organic Matter in Coking Coal

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.