水溶性沥青分子结构的光谱解析

Spectral Analysis of Molecular Structure of Water-Soluble Pitch

水溶性沥青是煤焦油沥青经酸氧化改质得到的水溶物含量大于70%的改性沥青,不仅兼有普通沥青的多环芳烃结构,同时表面结构中引入了大量含氧、氮、硫等极性官能团,可在水相中制备复合型炭材料。应用荧光、红外、紫外光谱及核磁共振技术并结合Yen-Mullins模型解析了混酸法制备的水溶性沥青的分子结构。结果表明:与中温煤沥青相比,主要杂原子N,O和S质量分数分别由1.06%,11.64%,0.79%增加到6.78%,29.59%,2.41%;O含量的显著增加,增强了沥青的亲水性。红外光谱体现了水溶性沥青的杂原子N,O和S以Ar—NO_2,Ar—OH,Ar—SO_3H和CO等形式存在;通过荧光发射光谱特征峰与Yen-Mullins模型对比,得出水溶性沥青的芳香结构主要是由3种稠环的"岛屿结构"芳香片段组成;~1H-NMR和^(13)C-NMR分析表明,水溶性沥青分子芳环侧链被氧化成仅含有1个C且链接不同官能团的脂肪碎片,该碎片与"岛屿结构"作为主要部分构成水溶性沥青分子的稳定结构。由此看出,元素分析结合红外光谱可从本质上解释水溶性沥青易溶于碱性水溶液的原因,荧光谱图与Yen-Mullins模型结合可从微观上解释水溶性沥青的主要结构,为判定不同性质的沥青提供一种方法。

Water-soluble pitch containing more than 70% of hydrophilic groups were prepared from the oxidation of coal tar pitch in the presence of acid, the product can be applied in the preparation of composite carbon materials in aqueous medium owing to a variety of introduced polarity groups and normal condensed rings. Moreover, the molecular structure was analyzed using Fluorescence, IR, UV, NMR and Yen-Mullins model. The results indicated that the fraction of N, O, S were increased by 1.06%, 11.64%, 0.79% to 6.78%, 29.59% and 2.41% respectively. In addition, the hydrophilicity of the desired pitch enhanced that was attributed to the O percent increased. Hetero-atoms （N, O, S） exist in the form of Ar—NO2, Ar—OH, Ar—SO3H and CO were characterized by infrared spectroscopy. Three fused aromatic rings called “Island structure” were identified by fluorescence and Yen-Mullins model, substitutions on aromatic rings were oxidized to a single C-atom group as shown by 1H-NMR and 13C-NMR spectra, this group and “Island structure” can be seen as the basic composition of water-soluble pitch’s framework. It was found that pitch was soluble in alkaline aqueous solution can be explained by elemental analysis combined with infrared spectroscopy, and fluorescence spectrum combined with Yen-Mullins model gave the main structure information from a microcosmic view, thus enabling a general method for different properties pitch determination.