Imidazole-based ionic liquids as rheological modifiers of heavy crude oil: An experimental and theoretical study

Abstract

Two series of imidazolium-based ionic liquids (ILs) were tested as rheological modifiers of heavy crude oils. ILs with the 1-butyl-3-alkylimidazolium cation optimize the effect on viscosity at low concentrations, whereas those with the 1-benzyl-3-alkylimidazolium cation are similarly effective only at higher concentrations, which is due to a stronger IL–IL interaction with respect to the IL–asphaltene interaction. The most effective ILs were [C6bim][PF6], [phetbim][PF6], and [C9bim][NTf2], with viscosity falling in the order of 44.0%, 38.2%, and 32.9%, respectively. An analysis of structural features suggests that the type of anion and the strength of the ion pair interaction play an important role in the capacity of the salts to interact with the crude oil components. In addition, computational methodologies, such as atoms in molecules and non-covalent interactions, were used to analyze the main intermolecular interactions between the most effective [C6bim][PF6] and two different substructures of an asphaltene model. According to these results, hydrogen bonding (F⋯H–C, F⋯H–N, and O⋯H–C), C–H–π, and van der Waals interactions contribute to the breaking up of the π–π stacking interactions between the complexes resulting from the self-association of the aromatic compounds; as a consequence, the crude oil viscosity decreases.

Insight into the oil removal mechanism of quaternary ammonium ionic liquid microemulsions for oily sludge treatment

“…Zhu et al 22 chose a [C 16 mimCl]/ndodecane/n-pentanol/water microemulsion system to separate coal slime from coal, which signicantly decreased the treatment cost. Martínez-Mora et al 23 found that the length of the alkyl chain and charge density of anion ions inuenced the p-p interaction between asphaltenes, i.e., cations with longer alkyl chains could disperse asphaltenes better. Moreover, ILs containing Cl − were more effective in hindering p-p interactions than those containing Br − , BF 4 − , or PF 6…”

Role of Ionic Liquid in Asphaltene Dissolution: A Combined Experimental and Molecular Dynamics Study

“…C 23 H 36 BrN IL was more effective in reducing the viscosity of the heavy crude oil in comparison to the C 18 H 35 BrN 2 , C 19 H 34 BrN, C 23 H 42 Br 2 N 4 , C 23 H 39 BrN 2 , and C 17 H 38 BrN ILs. Martinez-Mora et al performed experimental and theoretical analysis of heavy crude oil rheological properties in the presence of imidazolium-based ILs. Their results showed that the considered 24 ILs reduced the viscosity of the heavy crude oil, where ILs [C 6 bim]­[PF 6 ], [phetbim]­[PF 6 ], and [C 9 bim]­[NTf 2 ] were the most effective in reducing the viscosity in comparison to other considered ILs.…”