Abstract:

The molecular structures of nitrogen compounds change regularly with the increase of oil distillation range. The relationship between the molecular structure of the nitrogen compounds and the hydrogenation behavior is an important guiding theory for the design of hydrodenitrogenation (HDN) catalysts. This study used theoretical calculation to investigate the variation in the properties and reaction behaviors of basic and non-basic nitrogen compounds with their structures. The results showed that the adsorption strength and charge transfer increased with the number of aromatic rings on the nitrogen compounds. In addition, the horizontal adsorption gradually became the dominated morphology instead of vertical adsorption. As the number of aromatic rings increased, it became more difficult to break C—N bonds through a low activation energy pathway. Instead, the bonds could only be broken through the substitution pathway with a high activation energy. Therefore, the break of the C—N bond required the saturation of the aromatic rings through full hydrogenation. The major nitrogen compounds in the products of the high hydrogenolysis capacity catalyst were polycyclic aromatics, whereas those of the catalyst with high hydrogenation saturation capacity contained more compounds with double aromatic rings. The results of hydrogenation experiments indicated that the catalyst with high hydrogenolysis ability offered higher HDN activities for the light distillate, whereas the catalyst with high hydrogenation ability performed better for the heavy distillate.

Key words: heavy oil, hydrogenation, structure of nitrogen compounds, quantum chemistry, catalyst

摘要：

氮化物分子的结构随着油品馏程增加呈规律性变化，氮化物结构与加氢行为之间的关系是重油加氢脱氮催化剂设计的重要指导理论。本文采用量子化学理论计算的方法研究碱性氮化物和非碱性氮化物的理化性质与反应行为随氮化物结构的变化规律。研究发现，随着氮化物中共轭芳环数目的增加：氮化物吸附能力增强，且吸附过程中电荷转移能力也随之增强，氮化物的平躺吸附逐渐占优势；C—N键通过低活化能的消去路径断裂的难度增加，只能通过高活化能的取代反应路径实现断裂，这就要求与氮化物相邻芳环在C—N键断裂前必须充分得到加氢饱和。高氢解能力催化剂加氢产物中剩余氮化物以含有多环芳烃的氮化物为主，而高加氢饱和能力催化剂加氢产物剩余氮化物中含有更多的双环氮化物，加氢实验结果说明了具有高氢解能力的加氢催化剂更有利于轻质油品中氮化物的脱除，而具有高加氢饱和能力的催化剂更有利于重质油品中氮化物的加氢脱除。

关键词: 重油, 加氢, 氮化物结构, 量子化学, 催化剂