Naphthenic acids (NAs) are complex mixture of predominately alkyl-substituted cycloaliphatic carboxylic acids and small amount of acyclic acids present in crude oil, heavy oil and in oil sands bitumen. They are toxic components in refinery wastewater and in oil sand extraction water and lead to corrosion problems within the oil refineries. Therefore, the amount of NAs needs to suppress in petroleum oils and wastewater came from petroleum industry. This paper reviews the supercritical fluids (SCFs)- and ionic liquids (ILs)-based acidity reduction process from heavy oils by reviewing open literature. The potential benefits of SCFs- and ILs-based acidity reduction process of heavy oils are also explored. The reviewed articles reveal that total acid number (TAN) removal increase with increasing reaction time and temperature by the action of SCF. Supercritical methanol (SC-MeOH) has higher potentiality for removing acidity of NAs than supercritical water (SCW) without deposition of coke. TAN removal from NAs using SCF follows first order kinetics on TAN removal. ILs can reduce acidity of heavy oil either forming zwitterionic species or building cage structure around NAs through specific chemical bonds. Thus, non-catalytic SCF- and ILs-based TAN reduction process can open a new window to reduce acidity of heavy oils.
Part of the book: Recent Insights in Petroleum Science and Engineering
Heavy metals containing compounds present in heavy oils create particular problems on their upgradation and refinement processes. The aim of this work is to extract nickel (II) tetraphenylporphine (NiTPP) from model heavy oils using ionic liquids (ILs). Exploring open literature, four different ILs such as 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM]TFSI), 1-ethyl-3-methylimidazolium octyl sulfate ([EMIM]OS), 1-butyl-3-methylimidazolium octyl sulfate ([BMIM]OS), and 1-methyl-3-octylimidazolium tetrafluoroborate ([OMIM]BF4) were utilized in this study. Potential experiments were conducted in a batch-type extractor (design temperature of 250°C and pressure of 6 MPa) at temperatures of 0–180°C. The extracted samples were analyzed using UV-visible spectrophotometer to determine the concentration of metallic compounds. The results show that NiTPP extraction was increasing with increasing temperature and treatment time and approximately 63% NiTPP was extracted in [BMIM]OS at a temperature of 100°C and a treatment time of 40 min. It is also observed that NiTPP extraction was decreasing above temperature 100°C. The extraction kinetics followed first-order kinetics with respective activation energy and pre-exponential factor of 1.24 kcal per mol and 2.156 × 10−3 s−1. Therefore, the IL, [BMIM]OS, is capable to extract NiTPP from model heavy oils at temperatures below 100°C indicating the effectiveness of this IL to extract NiTPP from heavy oils.
Part of the book: Processing of Heavy Crude Oils