Naphthenic acid extraction and speciation from Doba crude oil using carbonate-based ionic liquids

• Published in: Fuel
• Main Authors: Anderson, K., Atkins, M. P., Goodrich, P., Hardacre, C., Hussain, A. S., Pilus, R., Rooney, D. W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: Naphthenic acid; Methylcarbonate ionic liquid; Extraction; Neutralisation; Regeneration; Recycle; VACUUM FRACTION; REMOVAL; WATER; DECARBOXYLATION; CATALYSTS; CORROSION; SOLVENTS; Carbonic acid
• Online Access: https://research.manchester.ac.uk/en/publications/2ba3bae0-48a4-4b27-8806-e08fbfc59717; https://doi.org/10.1016/j.fuel.2015.01.015

A number of tetraalkylammonium methylcarbonate and hydrogencarbonate based ionic liquids are shown to be capable of reacting with the naphthenic acids contained in Doba crude oil via a neutralisation reaction. Spectral studies show that the ionic liquids neutralisation mechanism involves the formation of an ionic liquid-naphthenate complex, liberating methanol and carbon dioxide. Extraction of the neutralised complex into a separate methanol phase and subsequent regeneration using aqueous carbonic acid results in ?70% of the ionic liquid being recovered for recycle. Isolation of the naphthenic acids shows that these make up to 0.85 wt% of the crude oil. Speciation of the naphthenic acids shows a mixture of monocyclic, through to tetracyclic structures with carbon numbers in the range C 12 -C 40 .