石油中不同环数芳烃化合物的精细分离和制备

An improved column-chromatographic separation for polycyclic aromatic compounds in petroleum

石油族组分的分离和制备过程是后续分子组成、同位素分析的基础。由于同分异构体多,传统技术制备的芳烃化合物组分仍然无法满足单体化合物的同位素分析要求。采用两种不同的分离方案对原油中的多环芳烃进行精细的分离和制备,其中"一步法"是直接将脱沥青质的原油样品经过一次氧化铝/硅胶层析柱,用不同体积比的石油醚/二氯甲烷混合溶剂进行洗脱;"两步法"先将原油采用常规的族组分分离方法得到芳烃馏分,再将芳烃馏分经氧化铝层析柱,用不同比例的石油醚/二氯甲烷混合溶剂进行洗脱,可得到不同环数芳烃的组分。对洗脱出来的不同组分进行色谱—质谱分析(GC-MS),与"一步法"相比,"两步法"可以更好地实现单环、双环与三环芳烃化合物的分离制备,其中,石油醚/二氯甲烷(99/1,V/V)的混合溶剂可以制备单环芳烃化合物;石油醚/二氯甲烷(9/1,V/V)混合溶剂可制备得到以双环芳烃化合物占绝对优势的组分;石油醚/二氯甲烷(8/2,V/V)混合溶剂则可制备得到三环芳烃化合物组分。

The separation and preparation process of petroleum group components is the basis for the subsequent molecular composition and isotopic analysis.Due to the complex composition of isomers,the components of aromatic compounds prepared by traditional techniques still cannot meet the isotopic analysis requirements of specific compounds.Two different separating methods were used to finely separate and prepare polycyclic aromatic hydrocarbons in crude oils.The“one-step method”was to directly pass the de-asphalted crude oil samples through an alumina/silica gel chromatography column,and elute them with different ratios of petroleum ether/dichloromethane mixed solvent.The“two-step method”firstly used conventional separation methods to obtain aromatic fraction from crude oils,and then applied the aromatic fraction to a column filled with alumina and sub-fractions with different ring numbers then eluted with mixed solvent with different ratios of petroleum ether/dichloromethane.Gas chromatography-mass spectrometry(GC-MS)analysis for the sub-fractions were carried out for the comparison between the two separation methods.Results show that the“two-step method”can better realize the separation and preparation of monocyclic,bicyclic and tricyclic aromatic compounds.The mixed solvents of petroleum ether/dichloromethane of V/V:99/1,9/1 and 8/2 can obtain monocyclic,bicyclic and tricyclic aromatic compounds respectively.