渤海稠油及其组分中杂原子化合物的负离子电喷雾-高分辨质谱分析

摘要

采用沉淀法和色谱分离法将渤海某油田稠油分离成沥青质、胶质、剩余分3个组分.采用负离子电喷雾技术(ESI)结合高分辨傅立叶变换离子回旋共振质谱仪(FT-ICR MS)研究了该稠油及各组分的分子组成.结果表明,剩余分中有较少的极性杂原子化合物能被负离子ESI电离,如N1,N1O1,O1和O2类,其等效双键数(DBE)较小.胶质和原油中极性化合物有相同的杂原子类型,包括N1,N1O1,N1O2,N2,N2O2S1,O1,O2,其中胶质和原油中N1,O1,O2类化合物的DBE-碳数分布图相似.沥青质中富集高缩合度且多杂原子的酸性化合物,如含杂原子N,S的氧化程度高的化合物(N2O1,N1O3,S1O3)及O3类化合物,这些物质具有较高的界面活性,易吸附在界面上促进界面张力降低和增强界面膜强度,从而有利于乳状液稳定存在.N1O1,N1O2,N1O3类化合物,N2O1类化合物可能分别是N1化合物,N2化合物的氧化降解产物;随着氧化降解程度增加,降解产物的极性明显增强.%Bohai heavy oil was separated into asphaltene,resin and remaining fraction by precipitati-on and silica gel chromatography.Molecular compositions of Bohai heavy oil and its fractions werecharacterized by Fourier transform ion cyclotron resonance(FT-ICR) mass spectrometry (MS) with negative ion electrospray ionization (ESI).The results showed that less polar molecules containing N1,N1O1,O1,O2 compounds with low double bonds equivalent(DBE) in remaining fraction could be ionized by ESI.The heteroatom classes and the distribution patterns of N1,O1,O2 class species in the resin fraction and crude oil are similar,and the heteroatoms classes contain N1,N1O1,N1O2,N2,N2O2S1,O1,O2 classes.The asphaltene fraction contains acidic compounds with high degree of condensation and high order heteroatom,such as N1O3,S1O3,N2O1 and O3 species,which have high interfacial activity.They could promote the reduction of interfacial tension and the strength of interfacial film through adsorbing at oil-water interface.N1 O1,N1O2,N1O3 class species could be the oxidation degraded products from N1 compounds,and the N2O1 class species could be generated by oxidizing degradation of N2 compounds.And the polarity of degraded products increases obviously with the increase of oxidizing degraded degree.