钌离子催化氧化法研究大港减压渣油组分化学结构

利用钌离子催化氧化方法对大港减压渣油芳香分、胶质和庚烷沥青质进行了选择性降解，通过GC、GC-MS等分析手段对降解反应产物中一元正构脂肪酸、α,ω-二元正构脂肪酸和苯二～六元羧酸的含量和分布分别进行了定量分析。结果表明，芳香分、胶质和庚烷沥青质中的芳香结构上都存在大量烷基取代基和桥接不同芳碳的聚亚甲基桥。烷基取代基碳数最大约为33，聚亚甲基桥最大碳数约为24，而且这两种结构单元的含量均随碳数的增加而减少，并呈现出了偶碳优势。庚烷沥青质C12以下侧链相对较多而C16＋较少，与芳香分的分布相反；正构烷基侧链的浓度按庚烷沥青质、胶质和芳香分的顺序递减。降解产物中都检测到了苯二甲酸到苯六甲酸等一系列的苯多酸，表明三个组分中都存在稠环芳香结构。庚烷沥青质中缩合程度较高的迫位缩合结构含量最高，芳香分渺位缩合结构最多，胶质介于两者之间。

Chemical structural features of fractions from Dagang vacuum residue

Dagang vacuum residue was separated into four fractions (saturates, aromatics, resins, and asphaltenes, known as SARA) by chromatography. The features of molecular structure of aromatics, resins and asphaltenes were investigated by ruthenium-ion-catalyzed oxidation (RICO), where involatile acid products were methylated with excess diazomethane ether and volatile acids were esterified with phenacyl bromide. Based on GC-MS and GC analysis of these esters, homologous series of n-alkanoic acids (C4~33), α,ω-di-n-alkanoic acids (C3~24) and benzenepolycarboxylic acids were determined. The results indicate that the number of n-alkyl groups and polymethylenes connected to aromatic carbons decreases with an increase of the substituent chain length; it is characterized by an even-to-odd carbon number preference. Asphaltenes have relatively more short (C16) alkyl chains attached to aromatic carbons than resins and aromatics. Benzenedi through hexacarboxylic acids occurred in the RICO products prove the presence of polycyclic aromatic structure and can give a sight on the major mode of aromatic condensations in the fraction sample. The aromatic nuclear in asphaltenes have more peri-condensation structure units than that in aromatics. Cata-condensation modes are more abundant in aromatics.