Abstract
In order to investigate the nature of petroleum asphaltenes in
terms of polarity a process was developed using initial
liquid-liquid extraction of the oil phase followed by
precipitation of the asphaltenes using n-heptane. The
liquid-liquid extraction was performed using toluene-methanol
mixtures with increasing content of toluene. Although large
fractions of the crude oil (Alaska ´93) was extracted in the
higher polarity solvents (high concentration of methanol), the
asphaltene content of the dissolved material was low. As the
toluene content increased more asphaltenes were transferred to the
solvent phase. The asphaltenes were analysed using FTir, Elemental
analysis, and HPLC-SEC with a diode array detector. With
increasing content of toluene in the methanol the molecular weight
distribution of the asphaltenes significantly move to higher
molecular weights. The content of nitrogen and sulfur of the
maltene phase also increase while H/C decreases. The content of
heteroatoms in the asphaltenes are relatively higher and
apparently increase with the polarity of the solvent. It is
concluded that these asphaltenes are indeed dominated by high
molecular weight substances that cannot be extracted in the high
polarity solvents.
Original language | English |
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Journal | Petroleum Science and Technology |
Volume | 15 |
Issue number | 1-2 |
Pages (from-to) | 185-198 |
ISSN | 1091-6466 |
DOIs | |
Publication status | Published - 1997 |