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Due to the depleting production of conventional petroleum, heavy oil is turned to as an alternative. However, the presence of trace nickel and vanadium in heavy oil poses problems for the refining process in producing lighter-end products. Such problems are its tendency to poison the catalyst, accumulate during distillation, and corrode the equipment. The objective of this work is to remove the metal porphyrins from model oil using the thermally stable ionic liquid 1-butyl-3-methylimidazolium octylsulfate, [BMIM][OS] assisted by subcritical toluene (above boiling point, 110.6°C and below a critical point, 318.6°C at 41.264 bar) in a novel attempt. The experiments were conducted at 150ºC to 210ºC under a mixing time of 30 to 90 minutes while the pressure was monitored. Four metal porphyrins are used: nickel etioporphyrin, nickel tetraphenylporphyrin, vanadium oxide etioporphyrin, and vanadium oxide tetraphenylporphyrin. The results show that more than 40% of removal is achieved for all metal porphyrins, which shows great potential for further technological improvement. The Nuclear Magnetic Resonance (NMR) shows that the ionic liquid did not decompose at the process temperature, which proves great stability. The extraction of metal porphyrins follows the second-order extraction model with an R2 of more than 0.98.

The surging demand for unconventional oil has driven the research initiative to extract heavy metals from heavy crude oil to ease the upgrading processes and produce lighter-ends hydrocarbon to be supplied in the field of transportation and petrochemical industry. Despite multiple methods have been discovered for metal removal, the low efficiency removal had enlightened the need of using ionic liquids. Three ionic liquids are studied in this project which are 1-butyl-3-methylimidazolium octylsulfate (BMIMOS), 1-ethyl-3-methylimidazolium octylsulfate (EMIMOS) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMNTf2) on extraction of two complex heavy metals; nickel etioporphyrin and vanadium oxide etioporphyrin. The experiments were tested at temperature ranging from 30 °C to 90 °C and 30 minutes to 90 minutes of mixing time. In addition, samples were analysed through UV-Visible Spectroscopy (UV-Vis) and Fourier Transform Infrared (FTIR) to determine the effectiveness of the extraction and study the functional group presence in the samples accordingly. Results revealed the overall maximum extraction efficiency of 22% of Ni-EP was recorded by EMIMNTf2. The changing in reaction temperature and time did not affect the percentage of Ni-EP removal by EMIMNTf2.

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