Abstract Hydrotreatment (HDT) of low-temperature coal tar (LCT) were carried out in a fixed-bed hydrogenation equipment under various reaction pressures. Asphaltenes were characterized by elemental analysis (EA), gel permeation chromatography (GPC), and proton nuclear magnetic resonance (1H-NMR). As the reaction pressure increased from 6 to 12 MPa, the content of toluene insoluble compounds and asphaltenes as well as the polydispersity of asphaltenes decreased gradually, indicating that the increase of pressure inhibited the condensation reaction of macromolecular radicals to produce toluene insoluble substance. What’s more, the removal rate of sulfur and nitrogen increased about 20% and 3%, respectively. This phenomenon revealed that sulfides were gradually removed as reaction pressure increased, owing to different removal degree of alkylates, thioethers, sulfoxides and sulfones in sulfides of LCT asphaltenes. By contrast, the increase of reaction pressure had negligible effect on removal rate of nitrogen because aromaticity (fA) of LCT asphaltenes is high and nitrogen mainly exist in the form of heterocyclic nitrides (more than 85%), which are difficult to be removed. By analyzing the structure, fA of LCT asphaltenes tended to decrease and the condensation degree parameter of the aromatic ring system (HAU/CA) increased gradually, indicating that the aromatic of the asphaltenes’ unit layers lessened and the condensation degree of aromatic rings decreased. In addition, the naphthenic ring number (Rn) remains almost unchanged, while the aromatic ring number (RA) reduced with the increase of pressure, demonstrating that the ring-opening rate of naphthenic ring is slightly larger than the hydrogenation saturation rate of aromatic ring during the HDT process of LCT.

中文翻译：

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不同反应压力下低温煤焦油加氢处理沥青质的组成和结构研究

摘要 低温煤焦油（LCT）加氢处理（HDT）是在固定床加氢设备中在不同反应压力下进行的。沥青质通过元素分析 (EA)、凝胶渗透色谱 (GPC) 和质子核磁共振 (1H-NMR) 进行表征。随着反应压力从 6 增加到 12 MPa，甲苯不溶物和沥青质的含量以及沥青质的多分散性逐渐降低，表明压力的增加抑制了大分子自由基缩合反应生成甲苯不溶物。硫和氮的去除率分别提高了20%和3%左右。这一现象表明，由于烷基化物的去除程度不同，硫化物随着反应压力的增加而逐渐去除，LCT 沥青质硫化物中的硫醚、亚砜和砜。相比之下，反应压力的增加对脱氮率的影响可以忽略不计，因为LCT沥青质的芳香性（fA）高，氮主要以杂环氮化物的形式存在（85%以上），难以脱除。通过结构分析，LCT沥青质的fA趋于降低，芳环体系的缩合度参数（HAU/CA）逐渐升高，表明沥青质单元层的芳香性减弱，芳环的缩合度降低。此外，环烷环数（Rn）几乎保持不变，而芳环数（RA）随着压力的增加而减少，