Determination of sulfur compounds in non-polar fraction of vacuum gas oil

Abstract

Sulfur compounds in the non-polar fraction, which represents 73 wt% of total sulfur in a vacuum gas oil (VGO), were analysed by sulfur-selective ligand exchange chromatography combined with high-performance liquid chromatographic (h.p.l.c.) separation on the basis of aromatic ring number, with subsequent capillary g.c.-mass spectrometry for identification. Quantification was achieved by independent h.p.l.c. separation based on aromatic ring number followed by capillary gas chromatography with a sulfur-selective flame photometric detector. These methods were very effective in isolating the sulfur compounds from complex mixtures of high-boiling hydrocarbon compounds and for separating the sulfur compounds according to aromatic ring number. The structures and concentrations of > 100 sulfur compounds in the non-polar fraction of the VGO were determined Alkyl benzo[ b]thiophenes, dibenzo[ b,d]thiophenes, benzonaphthothiophenes and phenanthro[4,5- b,c,d]thiophenes were found to be major sulfur species existing in the non-polar fraction of the VGO.