Imidazolium‐based poly(ionic liquid)s for demulsification of water in crude oil emulsions

Abstract

Imidazolium‐based ionic liquids (ILs) and their corresponding poly(ionic liquid)s (PILs) as powerful demulsifiers for water separation from the crude oil emulsions were used. Vinyl imidazolium‐based ILs were prepared and then polymerized according to the free radical homo‐polymerization. NMR and FT‐IR analyses confirmed the successful synthesis of ILs and their corresponding polymers. Demulsifying properties of different synthetic ILs, including [C12‐VIM][Br], [C10‐VIM][Br], [C8‐VIM][Br], [C6‐VIM][Br], [C4‐VIM][Br], and [Benzyl‐VIM][Br]) and their analogous poly(ionic liquid)s were evaluated and compared with each other. The influence of the important parameters on the emulsion breaking such as demulsifier concentration, the alkyl chain length of the synthesized demulsifiers, and the operating factors such as the stirring rate, stirring time, and temperature were investigated through the bottle test. Maximum dehydration efficiencies around 99.2% for [C12‐VIM][Br] at 400 ppm and 100% for P[C12‐VIM][Br] at 50 ppm were achieved after 4 hours at 70°C, 15 minutes stirring time, and 800 rpm stirring rate. After demulsification of the crude oil emulsions, the interfacial tension decreased from 22.18 ± 0.1 to 0.83 ± 0.2 mN/m for [C12‐VIM][Br] and from 20.18 ± 0.2 to 0.70 ± 0.2 mN/m for P[C12‐VIM][Br]. The average diameter of the water droplets increased from 2‐10 ± 0.63 to 30‐140 ± 0.51 for [C12‐VIM][Br] within 20 minutes. In addition, the residual water content decreased from 20% to 0.04% for [C12‐VIM][Br] within 24 hours.

Swelling poly(ionic liquid)s for demulsifying oil‐in‐water emulsion by anion exchange

“…With the alkyl chain of 3‐substituents on imidazolium increased from n ‐ethyl, n ‐butyl, n ‐hex1yl to n ‐octyl, the demulsification efficiencies of ILs were increased from 9%, 18%, 96% to 99%. It has been reported that the interfacial tension of ILs decreased when the chain length of ILs increased from n ‐butyl, n ‐hex1yl to n ‐octyl 31 and the diminution of interfacial tension promoted the migration of surfactant species to the interface 44 . These might be due to the ILs with longer alkyl chain have higher affinity to migrate to the interface, displace the surfactants and eventually destabilize the stability of emulsion 45 …”

“…PILs based on ammonium 25–28 and imidazolium 29 were used for demulsification of crude oil emulsions. Ezzat et al 30 and Ebrahim et al 31 found that PILs had better demulsification efficiency than their monomeric ionic liquids under the identical experimental conditions. These PILs were linear polymers and dissolved in the water, making them impossible to be recycled after demulsification.…”

“…Poly(ionic liquid)s (PILs) had IL species in their repeating units and applied to breaking emulsions 24–31 . PILs had a tendency to diffuse in the continuous phase of the oil/water emulsions, which enable them to achieve high demulsification efficiency 28 .…”

“…Poly(ionic liquid)s (PILs) had IL species in their repeating units and applied to breaking emulsions. [24][25][26][27][28][29][30][31] PILs had a tendency to diffuse in the continuous phase of the oil/water emulsions, which enable them to achieve high demulsification efficiency. 28 PILs based on ammonium [25][26][27][28] and imidazolium 29 were used for demulsification of crude oil emulsions.…”

In Situ Upgrading of Heavy Crude Oil: Comparative Study of the Performance of Cu-, Fe-, Ni-, or Zr-Containing Water-Based Catalysts

“…It is known that metallic sulfides can reduce the energy of the C–S and C–N in heteroatoms of sulfur and nitrogen which, in turn, have been identified as the main contributors to high viscosity of heavy crude oil streams. Including a small portion of metals in the catalyst may be sufficient to produce a notable reduction in the viscosity of heavy hydrocarbon streams …”