The Arabian Heavy (AH) crude oil was fractionated into distillate (&lt;C30) fraction and bottoms fraction. The distillate fraction and the whole crude oil were treated with supercritical water (SCW) in a batch reactor setup. The gaseous and liquid phase products were analyzed using gas chromatography (GC-MS, GCxGC FID, SCD) and proton NMR spectroscopy. The distillate fractions primarily consisted of n-alkanes (up to C30) plus a minor fraction of alkyl aromatics and sulfur compounds. SCW treatment of the distillate fraction resulted in mild cracking of the fuel alkyl groups, and production of gaseous species such as methane, ethane and propane. Model compound studies of SCW treatment of pure alkyl aromatics showed similar cracking chemistry. A detailed chemical kinetic model built by the Reaction Mechanism Generator software package, which contains only free radical and thermal chemistry, was in semi-quantitative agreement with product distributions measured in the model compound experiments. SCW treatment of crude oil including the heavy components caused much more dramatic changes. Much of the heavy component in the crude oil cracked to form compounds in the gasoline and diesel range which are analyzable by GC. There were also significant changes in the overall functional group distribution, as measured by NMR of the SCW treated crude oil. The concentration of alkenes increased dramatically, there were large shifts in the aliphatic region, and several new peaks were observed in the NMR spectrum of the treated oil, indicating new aromatics and possibly lower carbon number sulfur compounds are being formed. Despite being carried out at temperatures similar to those used in conventional thermal coking processes, the SCW process did not form significant amounts of coke. Overall, the SCW treatment of crude oil resulted in cracking of heavier hydrocarbon components into more valuable lighter molecules, which could be used in transportation fuel or as chemicals.

Supercritical water treatment of fractions of crude oil: Quantification of the products and model compound studies

251st National Meeting (2016)

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