中低温煤焦油加氢前后沥青质组成和结构变化

为更深入理解中低温煤焦油加氢过程中催化剂失活问题,在小型固定床加氢反应装置内进行煤焦油加氢实验,通过元素分析、平均分子量、红外光谱分析、1H-NMR和扫描电镜等方法研究煤焦油加氢前后沥青质组成和结构的变化。结果表明,加氢产物中沥青质质量分数降低,加氢沥青质平均相对分子质量减小,H/C原子比增加,硫、氮、氧杂原子含量降低;加氢后沥青质缩合度明显减小,沥青质在加氢反应过程中一方面发生烷基侧链和芳环取代杂原子(尤其是羟基氧)脱除反应,以及桥键断裂反应;另一方面发生环烷环和杂环开环、芳环加氢饱和反应。

Composition and structure changes of asphaltenes from medium and low temperature coal tar before and after hydrotreating

In order to better understand the problem of catalyst deactivation during the process of medium and low temperature coal tar hydrotreating，the hydrogenation experiment was carried out in a fixed-bed hydrogenation unit.The compositions and structure changes of asphaltenes from coal tar before and after hydrotreating were characterized by elemental analysis，molecular weight determination，Fourier transform infrared(FTIR) spectroscopy techniques，proton nuclear magnetic resonance(1H-NMR) and SEM，et al.The results show that the asphaltene content of hydrogenation products is reduced and the average molecular weight and the sulfur，nitrogen，oxygen content of asphaltene decrease，while H/C atomic ratio increases after hydrotreating.It has been seen that the reactions of removing of alkyl side chains and heteroatomic(especially the phenolic hydroxyl oxygen) and cracking of bridge bond occurr on the asphaltene during the process of hydrogenation.Meanwhile，the asphaltene naphthenic and heterocyclic rings opening and aromatic ring saturating reactions also occurr.All the above factors show that the degree of condensation of hydrotreated asphaltene decrease obviously.