Abstract

The composition of fragments linked by ester, ether, and sulfide bridges in heavy oil asphaltenes and in asphaltene components recovered from liquid products of their conversion at 300 and 450°C was studied by methods of selective chemical degradation and gas chromatography–mass spectrometry. The composition of “bound” fragments in molecules of secondary asphaltenes differs from that of products formed by cleavage of bridging bonds in molecules of the initial asphaltene samples and depends on the thermolysis temperature. At the initial thermolysis temperature, the mainly degrading fragments are those bound in the initial sample through the least thermally stable ester functional groups. An increase in the cracking temperature leads to the decomposition of bridges that link with each other structural fragments of macromolecules and separate aromatic clusters of the naphthene–aromatic system. Such bridges involve more thermally stable ether functional groups and С–S bonds in saturated and aromatic rings. The specific features of the distribution of “bound” fragments in the structure of the products of thermal degradation of the initial asphaltenes indicate that the asphaltene components of heavy oils contain molecules differing in the nature and position of sulfide, ether, and ester bridging bonds. The identified ether/ester-bound high-molecular-mass n-alkanes not only are covalently bound fragments but can also be occluded compounds that are released upon degradation of aromatic cores of asphaltene aggregates.

中文翻译：

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重油沥青质在热处理过程中的结构转变

摘要

通过选择性化学降解和气相色谱-质谱法研究了重油沥青质和在 300 和 450°C 下从其转化的液体产物中回收的沥青质组分中通过酯、醚和硫键连接的片段的组成。次生沥青质分子中“结合”片段的组成与初始沥青质样品分子中桥键断裂形成的产物的组成不同，并且取决于热解温度。在初始热解温度下，主要降解的片段是那些通过热稳定性最差的酯官能团结合在初始样品中的片段。裂解温度的升高会导致相互连接的大分子结构片段和环烷-芳族体系的芳族簇相互连接的桥的分解。这种桥涉及更热稳定的醚官能团和饱和和芳环中的С-S键。初始沥青质热降解产物结构中“结合”碎片分布的具体特征表明，重油的沥青质组分中含有不同性质和位置的硫化物、醚和酯桥键的分子。确定的醚/酯结合的高分子质量 初始沥青质热降解产物结构中“结合”碎片分布的具体特征表明，重油的沥青质组分中含有不同性质和位置的硫化物、醚和酯桥键的分子。确定的醚/酯结合的高分子质量 初始沥青质热降解产物结构中“结合”碎片分布的具体特征表明，重油的沥青质组分中含有不同性质和位置的硫化物、醚和酯桥键的分子。确定的醚/酯结合的高分子质量正构烷烃不仅是共价结合的片段，而且还可以是在沥青质聚集体的芳香核降解时释放的封闭化合物。