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摘要:
煤的化学成分从根本上决定了其转化和利用途径。煤分子模型的建立与模拟可以降低实验成本和时间，提高研究效率。复杂的成煤植物和沉积环境导致煤化学成分的复杂性，因此准确构建能够真实反映煤物理化学性质的分子模型对开展煤炭清洁高效利用的研究至关重要。以山西平朔矿区煤泥为样本，通过13C核磁共振波谱、傅里叶变换红外光谱、X射线光电子能谱研究了煤中C、O、N元素的赋存形式，确定了各元素相对含量。结果表明，平朔煤泥中煤不存在芳香甲基，碳元素主要以单环、多环芳香碳形式存在，氧元素主要以酯基、羟基等形式存在，氮元素主要以吡啶型氮形式存在。根据煤质分析结果，构建了分子式为C136H150O18N2的平朔煤分子模型。13C 核磁共振波谱预测验证与密度验证结果表明，模型谱线与实测谱线吻合度较高，模型密度与煤实际密度仅相差0.019 g/cm3，说明模型具有较好的代表性。这项研究为深入理解煤的化学结构提供了重要依据，也为煤的高效清洁转化奠定了理论基础。
Abstract:The conversion and utilization are fundamentally determined by the chemical composition of coal. The establishment and simulation of coal molecular model can reduce the experimental cost and experimental time, and improve the research efficiency. However, the chemical composition of coal exhibited significant complexity due to the complex coal−forming plants and depositional environments. Therefore, the accurate construction of coal molecular models, which can truly reflect the physical and chemical properties of coal, is essential for the research of clean and efficient utilization of coal. In this study, the coal slime from Pingshuo mining area in Shanxi Province was used as the research object. The relative contents and specific chemical states of carbon (C), oxygen (O), and nitrogen (N) were analyzed by 13C nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X−ray photoelectron spectroscopy (XPS). The results showed that Pingshuo coal slime does not contain any aromatic methyl groups. The carbon element mainly exists in the chemical form of mono− and polycyclic aromatic carbons. The oxygen element mainly exists in chemical forms such as ester group and hydroxyl group. The nitrogen element mainly exists in the chemical form of pyridine compounds. Based on the chemical analysis structure, the molecular model of Pingshuo coal slime was constructed. The molecular model of C136H150O18N2 was optimized by molecular simulation method, and the correctness of the model was verified by 13C NMR spectral line prediction verification and density verification. The 13C NMR spectrum prediction and density verification results showed that the model spectral line is in good agreement with the measured spectral line, and the difference between the model density and the actual density of coal is only 0.019 g/cm3, indicating that the model is well representative. This research provides a crucial molecular−level understanding of the coal's chemical architecture and establishes a robust theoretical foundation for developing efficient and clean coal conversion technologies.
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Key words:
- Pingshuo /
- coal slime /
- 13C NMR /
- FTIR /
- XPS /
- molecular model
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表 1 平朔煤泥工业分析结果
Table 1. Industrial analysis of Pingshuo coal slime
/% 成分 Mad Ad Vad FCad 含量 1.54 26.74 29.00 43.13 注：Mad空气干燥基水分；Ad空气干燥基水分；Vad空气干燥基挥发分；FCad空气干燥基固定碳。 
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表 2 煤泥元素分析结果
Table 2. Element analysis of Pingshuo coal slime
/% Cdaf Hdaf Odaf Ndaf St,d 78.55 5.03 13.36 1.33 1.26 注：Cdaf干燥无灰基碳元素含量；Hdaf干燥无灰基氢元素含量；Odaf干燥无灰基氧元素含量；Ndaf干燥无灰基氮元素含量；St,d煤中全硫含量。
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表 3 煤泥硫元素分析结果
Table 3. Sulfur elements forms in Pingshuo coal slime
/% St,ad Sp,ad Ss,ad So,ad 1.26 1.01 0.15 0.11 注：St,ad煤中全硫含量；Sp,ad硫铁矿硫含量；Ss,ad硫酸盐硫含量；So,ad有机硫含量。
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表 4 0~70 ×10−6峰的分峰拟合结果
Table 4. Peak fitting results of 0~70×10−6 13C NMR spectrum
化学位移
/10−6峰归属 峰数量 峰面积 峰面积
占比/%0~22 脂肪甲基 4 13558 22.54 22~26 芳香甲基 / / / 26~37 亚甲基 2 35184 46.64 37~50 次甲基 1 2333 19.00 50~100 氧−脂肪碳 5 9068 11.82 合计 12 60143 100.00
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表 5 （100~160）×10−6峰的分峰拟合结果
Table 5. Peak fitting results of (100~160)×10−6 13C NMR spectrum
化学位移
/10−6峰归属 峰数量 峰面积 峰面积
占比/%100~130 质子化的芳香碳 8 66557 66.27 130~140 桥碳 2 14264 14.20 140~148 烷基化芳香碳 1 7690 7.66 148~163 氧−芳香碳 2 11921 11.87 合计 13 100433 100.00
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表 6
2980 ~2800 cm−1分峰拟合结果Table 6. Peak fitting results of
2980 ~2800 cm−1 FTIR spectrum波数/cm−1 峰归属 峰宽 峰面积占比/% 2955 CH3反对称伸缩 23.92 11.02 2921 CH2反对称伸缩 34.93 44.61 2892 CH3对称伸缩 24.99 10.77 2855 CH2对称伸缩 44.13 33.60 合计 100.00
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表 7
1800 ~950 cm−1分峰拟合结果Table 7. Peak fitting results of
1800 ~950 cm−1 FTIR spectrum波数/cm−1 峰归属 半峰宽 峰面积占比/% 1713 羧酸羰基C=O伸缩 49.17 1.75 1608 芳香族C−C伸缩 95.80 21.88 1462 甲基、亚甲基 126.83 11.01 1439 甲基、亚甲基 52.63 3.87 1376 醇C−OH面内弯曲 71.10 6.34 1325 醇C−OH面内弯曲 53.12 2.54 1286 酚类C−OH伸缩 75.46 3.19 1256 酚类C−OH伸缩 77.96 5.89 1213 酚类C−OH伸缩 53.39 2.43 1183 酚类C−OH伸缩 57.03 3.51 1158 脂肪醚C−O 38.65 2.59 1133 脂肪醚C−O 25.40 1.90 1117 脂肪醚C−O 13.52 1.12 1106 醇类C−OH伸缩 14.36 0.38 1097 醇类C−OH伸缩 39.36 2.01 1086 醇类C−OH伸缩 48.38 8.08 1063 醇类C−OH伸缩 23.97 1.53 1034 芳香酯类C−O伸缩 36.11 14.08 1018 芳香酯类C−O伸缩 6.22 0.11 1010 芳香酯类C−O伸缩 13.76 2.95 998 无机盐类 13.76 1.64 985 无机盐类 18.00 1.20 合计 100.00
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表 8 C1s峰的分峰拟合结果
Table 8. Peak fitting results of C1s
峰归属 峰位置/eV 半峰宽 峰面积 峰面积占比/% C−C 284.8 1.02 245623.31 63.99 C−O 285.5 1.25 89976.52 23.44 C=O 286.5 1.45 48208.40 12.57 合计 383801.23 100.00
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表 9 N1s峰的分峰拟合结果
Table 9. Peak fitting results of N1s
峰归属 峰位置/eV 半峰宽 峰面积 峰面积占比/% 吡啶 398.8 1.9 3255.69 20.82 吡咯 400.2 1.5 9052.73 57.88 季氮 401.6 1.6 2516.31 16.09 氮氧化合物 402.9 1.8 815.01 5.21 合计 15639.74 100.00
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表 10 平朔煤结构参数
Table 10. Structural parameters of Pingshuo coal slime
质子化芳香碳参数(fHa) 芳香碳−氧参数(fPa) 烷基取代芳香碳参数(fSa) 芳香桥碳参数(fBa) 芳香环聚合度参数(Xb) 脂肪侧链长度参数(I) 66.27 11.87 7.66 14.20 0.166 0.279
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