煤基和石油基C7-沥青质的结构特征及缔合行为

Structure characteristics and association behavior of coal and petroleum C7-asphaltenes

采用核磁(NMR)、小角散射分析(SAXS)、X射线光电子能谱(XPS)、改进的B-L法等手段,研究了煤基C7-沥青质(CT-asp)和石油基C7-沥青质(M-asp)两类沥青质的化学组成、官能团和分子结构等组成结构特征以及差异性,进而通过极性溶剂中沥青质稳定参数研究两类沥青质的缔合行为和聚集体尺寸以及两者之间的氢键和酸碱作用。结果表明,CT-asp分子芳香环数较少且有较多短烷基侧链,且芳香度较高,较高含量氧杂原子以芳香醚和酚羟基赋存形态为主;而M-asp的芳香核尺寸和平均相对分子质量明显高于CT-asp,芳香环数虽较多且有较多长烷基支链,且芳香度较小;两类沥青质缔合聚集程度关联物质的量比(nCT-asp/nM-asp)及其分子结构特征,源于杂原子官能团的氢键和酸碱作用是两类沥青质缔合的主要作用力。

The structural characteristics and differences of coal tar and petroleum C7-asphaltenes were studied,such as chemical composition,functional groups and molecular structure,using nuclear magnetic resonance(NMR),small angle X-ray scattering(SAXS),X-ray photoelectron spectroscopy(XPS),improved B-L method and other methods.Furthermore,the association behavior and aggregation size of two different types of asphaltenes as well as the hydrogen bonds and acidic-basic interaction were analyzed by asphaltenes solubility parameters in polar solvents.The experiment results showed that the coal tar asphaltenes(CT-asp)was mainly composed of less aromatic rings with more short alkyl branched chains and possessed a high aromaticity degree.The higher content oxygen heteroatoms of CT-asp were mostly presented as aromatic ether bonds and phenolic hydroxyl groups.The aromatic nucleus size and the average relative molecular weight of petroleum asphaltenes(M-asp)were larger than that of CT-asp.The M-asp consisted primarily of more aromatic rings with more long alkyl branched chains and possessed a low aromaticity degree.The association and aggregation degree between CT-asp and M-asp was associated with the amount of substance ratio(ncr-asp/nM-asp)and their molecular structure characteristics.The association force of two types mainly was the hydrogen bonds and the acidic-basic interaction from heteroatomic functional groups.