渣油加氢转化过程中沥青质的结构变化

通过1H-NMR、元素分析和平均相对分子质量等方法研究了不同沥青质质量分数的渣油在高压釜内加氢反应前后沥青质结构和组成的变化。结果表明,加氢反应后沥青质的平均相对分子质量和H/C原子比减小,芳碳分率增大,芳香环系周边氢取代率σ及芳香环系缩合度参数HAU/CA减小,w（HA）增加,而w（Hα）、w（Hβ）、w（Hγ）减少,沥青质的取代芳碳分率减少,质子芳碳分率增加,表明加氢反应后所得沥青质的缩合度增大,沥青质发生了明显的脱烷基侧链反应。加氢后沥青质的含硫质量分数降低,含氮质量分数增加。随原料中沥青质质量分数的增加,加氢后沥青质的环烷环数和芳香环数均逐渐增加,尤其是芳香环数,甚至会大于原生沥青质。渣油加氢过程中沥青质主要是以单元薄片为基本单元参与反应的,沥青质的加氢反应,既有自由基反应,又有正碳离子反应。

Structure Changes of Asphaltene in Residue Hydrotreating

The asphaltene structure and composition changes pre-and post hydrotreating of residue with different asphaltene contents were researched by 1H-NMR,elemental analysis and molecular weight determination,et al.The results show that the molecular weight,H/C,σ,w（HAU）/w（C）,w（Hα）,w（Hβ）,w（Hγ）and substituted aromatic-carbon ratio of asphaltene decreased after hydrotreating;but aromatic-carbon ratio,w（HA）,protonic aromatic-carbon ratio increased.All above factors show that the condensation degree of asphaltene after hydrotreating is increased and asphaltene is dealkylation in residue hydrotreating.Sulfur in asphaltene decreased but nitrogen increased.The aromatic ring and naphthene ring of hydrotreated asphaltene increase with the increase of asphaltene content in feedstock.The aromatic ring numbers of hydrotreated asphaltene even more than that of original asphaltene.Asphaltene react in the forms of structure units in residue hydrotreating.The reaction mechanism of asphaltene in hydrotreating is free radical reaction and carbonium ion reaction.