The characterisation of crude oils and the analysis of by-products produced in petrochemical plants

  • Aboulgasim Wafa

    Student thesis: Master's Thesis


    The use of solid phase extraction (SPE) in conjunction with gas chromatography combined with mass spectrometry (GC/MS) has been evaluated for identifying aromatic compounds in crude oils. A standard hexane solution of polyaromatic hydrocarbons (PAHs) was used for SPE method development using a coupled silic cyano cartridge system. Quantitative GC/MS analysis confirmed that the SPE method developed provided potential for the high recovery of the PAHs within a single solvent fraction. The SPE method proved unsuccessful for the isolation of aromatic compounds from crude oil since the oil itself modified the mobile phase.

    Column chromatography with silica as stationary phase provided a means of fractionating crude oil such that the aromatic profile could be determined by GC/MS. With this approach in excess of forty aromatic compounds were found to be present within a sample of Libyan crude oil . The use of supercritical fluid extraction was also evaluated as a rapid means for the isolation of aromatic species from crude oil. The oil was loaded onto a silica support prior to extraction. Using high density supercritical fluid carbon dioxide only aliphatic hydrocarbons could be isolated from the crude oil sample.

    Studies involving chromatographic and spectroscopic techniques were also performed to characterise by-products associated with petrochemical plant and gas field industrial operations. An impurity isolated from a urea plant was tentatively identified as a polyamide species whereas an impurity obtained from a methanol plant was found to be composed of a mixture of hydrocarbons ranging from C-12 to C-33. A deposit obtained from the Sahel gas field was determined to be largely composed of a complex mixture of inorganic compounds.
    Date of Award1996
    Original languageEnglish

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