离子淌度飞行时间质谱表征减压蜡油加氢脱氮过程中氮化物的变化

Characterization of Changes in Nitrogen Compounds in Vacuum Gas Oil During Hydrodenitrification by Ion Mobility Time-of-Flight Mass Spectrometry

用配备了电喷雾电离源(ESI)的离子淌度飞行时间质谱(IMS-TOF MS),对不同温度下加氢的大庆减三线蜡油(VGO)中的碱性氮化物和中性氮化物进行了表征,探讨了加氢脱氮过程中氮化物的转化机理。氮元素分析结果表明,反应温度更高的加氢产物脱氮程度更深,大庆VGO的中性氮含量高于碱性氮,经过轻度脱氮处理后会出现中性氮含量低于碱性氮的情况,但深度脱氮后2种氮化物的含量相当。质谱表征结果显示:加氢前大庆VGO的中性氮化物以苯并咔唑和二苯并咔唑类化合物为主,碱性氮化物以吡啶类化合物为主。在脱氮程度较浅的大庆VGO样品里,中性氮化物的含量有所下降,还出现了环胺类碱性氮化物,这部分环胺类化合物在深度脱氮的大庆VGO样品中明显减少,说明中性氮化物经加氢后先生成了环胺类碱性氮化物,再进一步被加氢去除。研究结果表明,无论是中性氮化物还是碱性氮化物,不饱和度更高以及侧链更短、更少的氮化物都更容易被加氢去除。

Basic and neutral nitrogen compounds in Daqing VGO hytrotreated at different temperatures were characterized by Ion Mobility Time-of-Flight Mass Spectrometry(IMS-TOF MS)equipped with electrospray ionization(ESI),and the conversion mechanism of nitrogen compounds in the process of hydrodenitrogenation was explored.The results of nitrogen element analysis show that hydrogenated products at higher reaction temperature are denitrified more deeply,and the content of neutral nitrogen compounds in Daqing VGO is higher than that of basic nitrogen compounds.After mild denitrogenation,the content of neutral nitrogen compounds in Daqing VGO turns out to be lower than that of basic nitrogen compounds,while the contents of them are nearly equivalent after further denitrogenation.The results of mass spectrometry analysis demonstrate that the neutral nitrogen compounds in Daqing VGO before hydrogenation are dominated by benzocarbazole and dibenzocarbazole compounds,while basic nitrogen compounds are dominated by pyridine compounds.In mildly denitrified Daqing VGO samples,the content of neutral nitrogen compounds is decreased;basic nitrogen compounds such as cyclic amines can be also observed,which decrease significantly in deeply nitrified Daqing VGO samples,indicating that neutral nitrogen compounds are firstly converted into basic nitrogen compounds such as cyclic amines after hydrogenation,and then removed by further denitrogenation.The results show that the neutral and basic nitrogen compounds characterized with higher unsaturation degree,shorter side chain and less nitrogen compounds are easier to be removed by hydrogenation.