Removal of Naphthenic Acids from Beijiang Crude Oil by Forming Ionic Liquids

Abstract

More and more acidic crude oil has been exploited in the world. The presence of naphthenic acids in crude oil has a great influence on petroleum refiners. A new method was introduced to separate naphthenic acids from Beijiang highly acidic crude oil in this paper. The 2-methylimidazole solution in ethanol was used as the acid-removal reagent by mixing with the crude oil and then allowing the two phases to separate, with the naphthenic acids being extracted from the crude oil. Data indicated that the optimal content of 2-methylimidazole in ethanol was 20% (w/w) and the optimal extraction time was 10 min, with the reagent/oil ratio being 0.4:1 (w/w). The suitable reaction temperature could be room temperature. The total acid number of the crude oil was lowered from 4.18 to 1.38 mg of KOH/g, and the acid-removal rate could reach up to 67.0%.

Total Acid Number Reduction of Naphthenic Acids Using Supercritical Fluid and Ionic Liquids

“…Shi et al [86] has proposed a fancy method to isolate NAs from highly acidic crude oils by forming ILs. In this method, the researchers prepared BrØnsted ILs by acid-base reaction between basic imidazole and NAs to form naphthenates ILs according to the following reaction:…”

“…Treating of petroleum products for removing of NAs via a dilute caustic wash is a common industrial method. As an alternative of this process, the researchers are using organic bases such as glycolic solutions [28], monoethanolamine or 2-(Dibutylamino) ethanol [29] or imidazole derivatives [30] as alcoholic solutions. However, excess amount of organic base is required to reach good extraction process.…”

Perspectives of Ionic Liquids Applications for Clean Oilfield Technologies

“…In this method, the basic character of imidazole heterocycle is utilized to prepared Brønsted ILs by acid-base reaction between imidazole and naphthenic acids to form naphthenates ILs (Figure 4). Reagent recovery and naphthenic acids refining were also proposed (Shi et al, 2008 Fig. 4.…”

Current Knowledge and Potential Applications of Ionic Liquids in the Petroleum Industry

“…In regard to the crude oil refining industry, the usage of ILs has been reported for desulfurization (Huang et al, 2004;Zhang et al, 2004;Mochizuki and Sugarawa, 2008;Xu et al, 2009;Wang et al, 2010), denitrogenation Huh et al, 2009) and dearomatization ) of diesel and gasoline fuels as well as reduction of naphthenic acids in petroleum (Shi et al, 2008). In general, desulfurization, denitrogenation and dearomatization have been approached by mere extraction or extraction coupled with catalytic oxidation in ILs ( Figure 11).…”

“…Nevertheless, these approaches remain still far away from industrial application and more intensive research should be done in order to assay with real diesel or nafta streams, understand the catalysis and thermodynamics of reactions, recycling of sulphur-saturated ILs, finding applications for oxidized heteroatom-containing compounds, and scale up of the extractive and oxidative extraction processes. Finally, the presence of naphthenic acids in crude oil during refining operations may cause operational issues, such as foaming during crude oil desalting or other operation units as well as carrying cations through the refining process that may cause catalyst deactivation (Shi et al, 2008). They undertook an innovative approach to solve such a problem by forming ILs from the reaction of naphthenic acids and imidazole derivatives directly into the crude oil matrix, that allow ILs separation from crude oil.…”