Subfractionation, characterization and photooxidation of crude oil resins

Resins of five crude oils were obtained using SARA fractionation, The malte nic fraction of Blend Arabian Light, was further separated into six polar f ractions. These fractions which are the constituents of the resins were ana lysed by FTIR spectroscopy. They appeared to be more oxidized, more aliphat ic and less aromatic than asphaltenes. Photooxidation of resins showed that they are easily oxidizable and much more influenced by photooxidation than asphaltenes. The principal effect of photooxidation are: (i) increase of c arbonyl group amounts and particularly formation of carboxylic groups, (ii) oxidation of sulfoxide in sulfone group. (iii) oxidation of alkyl chains a nd of aromatic rings (quinone structures). (C) 2001 Elsevier Science Ltd. A ll rights reserved.