青海原油分子组成特征及其常压渣油含氮化合物加氢转化规律

Molecular Composition Characteristics of Qinghai Crude Oil and Hydrogenation Conversion Law of Nitrogen-Containing Compounds in Its Atmospheric Residue

利用气相色谱和高分辨质谱等手段分析了格尔木炼油厂的青海原油、常压渣油及渣油加氢产物的分子组成,发现青海原油中的硫、氮化合物具有特殊的分子组成,解释了该原油生产的催化裂化汽油中硫含量异常偏高及其常压渣油加氢脱氮率低的化学机理:含硫化合物富含噻吩结构单元,催化裂化过程中小分子噻吩在汽油中实现富集;氮化物烷基侧链较长,形成较强的空间屏蔽,抑制了加氢过程中氮的脱除。常压渣油加氢实验结果表明:高温裂化反应有利于提高常压渣油中氮元素的脱除率;常压渣油加氢过程中具有高缩合度的小分子含氮化合物被优先脱除,缩合度高的大分子氮化物发生芳环加氢反应形成部分饱和的中性氮化物,但芳环加氢反应仅发生在与中性氮化物氮原子未直接共轭的芳环上。

The molecular composition of Qinghai crude oil,atmospheric residue and hydrogenated products of residue from Golmud refinery was analyzed by means of gas chromatography and high resolution mass spectrometry.It is found that sulfur and nitrogen compounds in Qinghai crude oil have special molecular composition,which is used to explain the chemical mechanism for abnormal high sulfur content in fluid catalytic cracking(FCC)gasoline and low hydro-denitrification rate of atmospheric residue.Specifically,sulfur-containing compounds are rich in thiophene structural units,and small-molecular thiophenes are accumulated in gasoline during catalytic cracking;nitrogen compounds have long alkyl side chains and form strong space shielding,thus inhibiting the removal of nitrogen during hydrogenation.The hydrogenation experiment results of atmospheric residue show that high temperature cracking reaction helps improve the removal rate of nitrogen in atmospheric residue.In the hydrogenation process of atmospheric residue,small-molecular nitrogen-containing compounds with high condensation were preferentially removed,and large-molecular nitrogen-containing compounds with high condensation were transformed into partially saturated neutral nitrogen compounds after aromatic ring hydrogenation reaction,but the reaction only took place in the aromatic ring which was not directly conjugated with the neutral nitrogen atoms.