Composition of C10 to C12 Alkylnaphthalenes in Various Crude Oils

Abstract

The analyses of all C10 to C12 alkylnaphthalenes in nine crude oils were made by a combined chromatographic and spectrometric method.The di-aromatic fraction was isolated from the middle distillate (180∼300°C) of crude oil by liquid-solid chromatography, and analyzed by gas chromatography using a capillary column. The components inseparable by gas chromatography were determined by infrared spectrometry of the gas chromatographic effluent.The interference of alkylbenzothiophenes in the infrared spectrometry was avoided by removing them with liquid-liquid chromatography prior to the GC-IR analysis.The correction for alkylbenzothiophenes in the determination of some alkylnaphthalenes by capillary gas chromatography was made by using a sulfur selective flame photometric detector.The precision and accuracy of the method were both 5% relative.The compositions of C10 to C12 alkylnaphthalenes in nine crude oils were determined by this method and compared to each other. As a result, rules were found for the relative distribution of isomers. Furthermore, it was found that there was a marked difference in the relative distribution of isomers in high sulfur crude oils compared to low sulfur ones.