【目的】探究高精度煤的结构演化及其机理的定量表征。【方法】通过显微组分鉴定、镜质体反射率、工业品质、元素分析和光谱分析,确定了烟煤(FS1)和无烟煤(ZY1)碳骨架结构、官能团的赋存状态等信息,并通过计算机辅助分子设计建立2个分子结构模型。【结果】结果表明,随着煤化作用的进行,烟煤到无烟煤过程中,亚甲基的损失速率比甲基的损失速率快,芳香性增强,芳香环的脂肪族链变短且支化度较高,含氧官能团逐渐减少,煤结晶程度增强,煤的化学结构趋于成熟稳定,且煤中的脂肪碳减少,芳香碳增加,甲基碳和亚甲基碳含量减少。经过多次尝试确定了芳香炭、脂肪族侧链和氧官能团之间的键合模式,获得最终的分子结构模型:C175H162O13N2(FS1)、C190H159O5N3(ZY1).该模型较好地反映煤的真实结构,模拟的13CNMR光谱与实验光谱具有良好的一致性。上述研究为不同变质程度煤的分子结构演化提供了理论参考,为建立高可信度的分子结构表征提供了方法。

【Purposes】While extensive research has been conducted on the evolution of coal′s mo⁃ lecular structure during coalification, the heterogeneity and complexity of coal continue to impede the  accurate and precise quantitative characterization of its structural evolution mechanism. 【Methods】 Through maceral identification, vitrinite reflectance, industrial quality, elemental analysis, and spec⁃ tral analysis, the carbon skeleton structure and occurrence state of functional groups of bituminous  coal (FS1) and anthracite coal (ZY1) were determined. Two molecular structure models were estab⁃ lished by computer-aided molecular design. 【Finding】The results show that with the progress of coal⁃ ification, the loss rate of methylene is faster than that of methyl in the process of bituminous coal to an⁃ thracite, the aromaticity is enhanced, the aliphatic chain of aromatic ring becomes shorter and the de⁃ gree of branching is higher, the oxygen-containing functional groups is gradually reduced, the crystal⁃ linity of coal is enhanced, and the chemical structure of coal tends to be mature and stable. At the  sometime, the content of aliphatic carbon in coal decreases, the content of aromatic carbon increases,  and the content of methyl carbon and methylene carbon decreases. After several attempts, the bonding  mode between aromatic carbon, aliphatic side chain, and oxygen functional group was determined,  and the final molecular structure models were obtained: C H O N  (FS1), C H O N  (ZY1).  These models well reflect the real structure of coal, and the simulated  C NMR spectra are in good  agreement with the experimental spectra. The above research provides a theoretical reference for the  molecular structure evolution of coal with different metamorphic degrees, and provides a method for  establishing high-reliability molecular structure characterization.