Relation between the Distillation Characteristics and the Chemical Composition of Khafji Atmospheric Residue

Abstract

The study on the distillation characteristics and the chemical composition of Khafji atmospheric residue was made to obtain the basic information on the composition of individual fractions, which is necessary for developing an effective hydrodesulfurization process or utilizing these materials in more useful energy form. The Khafji residue was fractionated into seven distillates up to 325° C at 2 x10-3 mmHg and one residue by molecular distillation. The distillates and the residue were separated into saturated and aromatic components by silica gel liquid-solid chromatography. The n-paraffin content in the saturated components was determind by the formation of insoluble urea complex of n-paraffin. The oily substance which did not participate in the urea complex formation was treated with acetone at 3° C, whereby branched paraffinic material was precipitated. The remaining acetone soluble component was regarded as naphthene. The aromatic components was separated into two fractions by an alumina gel column. A detailed structural analysis of thus separated fractions was carried out by means of proton magnetic resonance spectroscopy. The yield of the molecular distillate was about 65% to the atomospheric residue, and the relative quantities of the saturated and the aromatic components in the distillates were similar as a whole.