赵锁奇 史权 王丽涛

摘 要：建立了基于酸、碱改性硅胶为固定相的萃取色谱分离方法，对VTB中的石油酸和含氮化合物进行分离。分离结果表明，羧酸约占VTB的3～5wt%，中性氮和碱性氮化物约占18wt%和13wt%。电喷雾（ESI）电离直接分析重油中含氮化合物和强酸性含氧化合物结果能够正确反映这些化合物的实际组成。通过萃取色谱分离，实现低含量和/或难电离化合物的组成分析。采用萃取色谱结合沥青质分离方法、CID、1H/13C-NMR和ESI FT-ICR MS等分析方法对可溶质、沥青质中的石油酸、氮化物和在碱改性硅胶上具有不可逆吸附的极性化合物进行了系统的分离和分子组成表征。可溶质中的石油酸主要是较低环数的环烷酸类化合物，而沥青质中则主要包含多环的环烷酸、芳羧酸类化合物。ESI FT-ICR MS分析沥青质得到的分子组成为沥青质中所含的酸性组分的组成信息，沥青质中占90wt%以上的非酸性组分无法在ESI电离源中电离。原料中能够被ESI FT-ICR MS检测的氮化物基本上都分布在胶质中，主要呈现出“孤岛”结构。沥青质虽然具有较高的氮元素含量，但无法在ESI电离源中电离。

关键词：石油酸 萃取色谱 组分分离 ESI FT-ICR MS 分子组成

Abstract：Extragraphic separation methods were established to isolate the petroleum acids and nitrogen compounds， based on using modified silica gel as stationary phase. There are about 3～5 wt% acid fraction， 18 wt% nonbasic nitrogen fraction， and 13 wt% basic nitrogen fractions in VTB. By extragraphic fractionation， the composition of molecules with low content and/or hard to be ionized was obtained. It is confirmed that a direct analysis of the nitrogen compounds and strong acids in heavy oil by ESI could reflect their real composition in raw material. Petroleum acids in maltenes are those naphthenic acids with small naphthenic rings， while multi naphthenic ring acids and aromatic acids are enriched in asphaltenes. The analyzable nitrogen compounds by ESI FT-ICR MS mainly distribute in resins， and mainly present as “island”structure. Materials in acid-free fraction which accounts for more than 90.0 wt% of asphaltene is not ionizable in an ESI source. About 3 wt% irreversible adsorption fractions were recovered from alkali treated silica gel and characterized to be strong polar compounds with highly condensed structure and short alkyl side chain.

Key Words：Petroleum acid；Extraction chromatography；ESI FT-ICR MS

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