Separation and characterisation of the C15- aromatic fraction of Safaniya crude oil

The purpose of this work is to isolate and characterise the light fraction of Safaniya, a conventional non-biodegraded type H crude oil. This fraction is devoted to perform a kinetic study on the thennal stability of the light aromatic fraction of crude oil. The light cut < 250 degrees C, corresponding to the C-15 components, was obtained by fractionated distillation. This cut contains saturated and aromatic hydrocarbons. Kinetic studies on the thermal stability of aromatics require to separate the aromatic fraction without ally trace of saturated compounds and derive detailed information on its composition. We have therefore developed a method permitting to achieve a clear-cut separation of these two families. Liquid phase chromatography on activated silica gel column was thus optimised for separating a complete and pure aromatic fraction, in large enough amounts for characterisation and all subsequent kinetic studies. Thereafter, Preparative High Performance Liquid Chromatography (PHPLC) of an aliquot was used to separate the aromatic compounds according to aromatic ring number into monoaromatics, indenes, diaromatics and biphenyls. Detailed molecular characterisation of the aromatic subfi-actions thus obtained was achieved by Gas Chromatography coupled to Mass Spectrometry (GUMS). Then, individual aromatic compounds were quantified by GC-FID. These compounds are benzene, C-1-C-7 benzenes, naphthalene, C-1-C-2 naphthalenes, indane, C-1-C-4 indanes, indene, C-1-C-2 indenes, C-1-C-3 tetralins and and sulphur-containing aromatics (niethyl- and ethylbenzothiophenes). The detailed knowledge thus derived on the composition of different class and its relative abundance in the total C-15 aromatics will allow following its temporal evolution during subsequent pyrolysis experiments.