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

Sulfur chemical species have been determined Fur asphaltenes, resins, and oil fractions of crude oils by using X-ray. absorption near-edge structure (XANES) spectroscopy. The prevalent sulfur species are thiophene, sulfide, and 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 large sulfoxide fractions are obtained fur all components of this oil. Another crude oil, lower in oxygen, also shows similar sulfur composition in all three fractions; nevertheless, the oil fractions of both crudes tend to have somewhat larger sulfide fractions.