气相色谱-飞行时间质谱联用仪测定柴油烃类分子组成的馏程分布

BOILING RANGE DISTRIBUTIONS OF HYDROCARBON MOLECULAR COMPOSITIONS IN DIESEL BY GAS CHROMATOGRAPHY-TIME OF FLIGHT MASS SPECTROMETRY

利用气相色谱-飞行时间质谱联用仪(GC-TOFMS)建立了测定柴油烃类分子组成的馏程分布的方法,可以得到柴油样品中各种类型烃类在不同馏程段的碳数分布与平均相对分子质量。利用所建方法研究了柴油中各种类型烃类平均分子结构随馏程的变化情况,发现柴油不同馏程段的平均相对分子质量与其芳烃含量和烃类异构化程度有关:芳烃含量越低、烃类异构化程度越高,该馏程段的平均相对分子质量越高。考察了柴油加氢精制前后烃类分子组成的馏程分布变化情况,柴油经加氢精制后,饱和烃的馏程分布基本不变,只是含量有所增加,芳烃的馏程分布在低馏分段没有变化,在高馏分段含量下降,导致产物的平均相对分子质量在高馏分段高于原料的平均相对分子质量。

A method for analysis of boiling range distribution of hydrocarbon molecular composition in diesel by gas chromatography-time of flight mass spectrometry （GC-TOFMS）was established. Car-bon number distributions,average molecular weights and structures of hydrocarbon in different boiling ranges were studied. It is found that the average molecular weight of distillation range was influenced by aromatic content and degree of isomerization. The lower the aromatic content and the higher the isomer-ization degree is,the higher average molecular weight of the boiling range is. The boiling range distri-butions of hydrocarbon molecular compositions in diesel before and after hydrotreating were investiga-ted. For hydrotreated diesel,boiling range distribution of saturated hydrocarbon is basically unchanged, but its concentration increases. Boiling range distribution of aromatic remains the same in low distillate fraction,whereas there is a concentration decrease in high distillate,which results in a higher average molecular weight of product than that of raw material diesel in high distillate fraction.