Determination of sulfur species in asphaltene, resin, and oil fractions ofcrude oils

Sulfur chemical species have been determined Fur asphaltenes, resins, and o il fractions of crude oils by using X-ray. absorption near-edge structure ( XANES) spectroscopy. The prevalent sulfur species are thiophene, sulfide, a nd sulfoxide. The asphaltene of one crude oil was known to have a very high sulfoxide content; the issue addressed here is whether the sulfoxide polar group is also dominant for sulfur in the resin and the (typically nonpolar ) oil fractions of the same crude oil. Results from this study show that la rge sulfoxide fractions are obtained fur all components of this oil. Anothe r crude oil, lower in oxygen, also shows similar sulfur composition in all three fractions; nevertheless, the oil fractions of both crudes tend to hav e somewhat larger sulfide fractions.