Nowadays, the use of preparative separations for the characterization of petroleum products is a common and routine practice in academic and industrial labs. In the area of petroleum chemistry, one of the pioneer works was carried out by Boduszynski who developed a gravimetric sequential elution fractionation method for separation of “non-distillable” petroleum residua into a set of well-defined fractions. In his work, Mietek supported the sample in a 50:50 w/w mixture of glass beads and Chromosorb-T, and after solvent removal, the dry residue-coated support material was then packed into a glass LC column. Four solvents, n-pentane, cyclohexane, toluene, and a mixture of methylene chloride/methanol (4:1 v/v), were pumped through the column and four solvent-derived fractions were collected and characterized. Inspired in this technique, we developed a methodology in which gram-quantities of petroleum samples were supported on grounded Teflon (40−60 mesh), and by using an accelerated solvent extractor apparatus, fractions were rapidly obtained. As Mietek did, we used four solvents of increasing polarity (heptane, 15:85 CH2Cl2/ heptane, 30:70 CH2Cl2/ heptane, and 100% CH2Cl2 and 90:10 CH2Cl2/Methanol) to extract the sample at room temperature and 100°C. The new method is relatively faster, requires less human intervention, uses temperatures up to 200°C, and good mass balances are obtained. In this talk, the application of this preparative methodology to the separation and characterization of asphaltene fractions from a crude oil and from a thermal cracking residue will be described.

Preparative separation of petroleum residua and asphaltene fractions using inert supports. Mietek’s pioneer work

253rd National Meeting (2017)

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