Extraction of naphthenic acid from highly acidic oil using phenolate based ionic liquids

• The extraction of naphthenic acid from highly acidic model oil was achieved.
• Very low ionic liquid/model oil ratio is necessary for the complete extraction of naphthenic acid.
• Phenolate based ionic liquids were reused three times without losing its activity significantly.
• COSMO-RS calculations were performed to get more insight into the extraction performance of phenolate based ionic liquids.

In this study, N-alkyl imidazolium ionic liquids with highly alkaline phenolate anions were used for the removal of naphthenic acid from model acid oil. The effect of alkyl spacer length on the deacidification process was evaluated by attaching butyl, hexyl, octyl, decyl and dodecyl groups on imidazolium cation. It was found that increase in the alkyl chain length increases the percent naphthenic acid removal. Extremely low amount of ionic liquids were necessary for the complete deacidification of model oil with high TAN. The reusability of the phenolate ionic liquids was also investigated. COSMO-RS calculations were performed on phenolate ionic liquids to study their extraction efficiency, selectivity and solvent capacity.

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