Dissolution and suspension of asphaltenes with ionic liquids

Ce Zheng, Manuel Brunner, Hua Li, Dongke Zhang, Rob Atkin

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Asphaltenes, which comprise polycyclic aromatic hydrocarbon cores with attached short aliphatic side chains, are the most polar fraction of crude oils. Asphaltenes are prone to precipitation, which requires expensive cleaning procedures using solvents like toluene or xylene. The toxicity and high vapour pressures of toluene and xylene means there is an urgent need for new liquids that are able to dissolve or suspend asphaltenes but are less environmentally problematic. This study reports treatment results of asphaltenes with 16 different ionic liquids covering three different types of cation charge groups, namely, cholinium, imidazolium and phosphonium with a wide variety of anions. The two oil-miscible ionic liquids, trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylphentyl)phosphinate and trihexyl(tetradecyl)phosphonium bis(2-ethylhexyl)phosphate, solubilised or suspended a significant fraction of raw asphaltenes. Elemental analysis, TGA and FTIR revealed that asphaltenes recovered from these ionic liquids had increased aliphatic and oxygen content compared to the raw material, and decomposed at lower temperatures during TGA test. The relative hydrophobicity of the ionic liquid is the major factor controlling the asphaltene mass in the ionic liquid, followed by the strength of interactions between ionic liquid and asphaltene alkyl groups. These findings provide a platform for the development of new ionic liquid based cleaners for asphaltene deposits.

Original languageEnglish
Pages (from-to)129-138
Number of pages10
JournalFuel
Volume238
DOIs
Publication statusPublished - 15 Feb 2019

Cite this

Zheng, Ce ; Brunner, Manuel ; Li, Hua ; Zhang, Dongke ; Atkin, Rob. / Dissolution and suspension of asphaltenes with ionic liquids. In: Fuel. 2019 ; Vol. 238. pp. 129-138.
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Dissolution and suspension of asphaltenes with ionic liquids. / Zheng, Ce; Brunner, Manuel; Li, Hua; Zhang, Dongke; Atkin, Rob.

In: Fuel, Vol. 238, 15.02.2019, p. 129-138.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Dissolution and suspension of asphaltenes with ionic liquids

AU - Zheng, Ce

AU - Brunner, Manuel

AU - Li, Hua

AU - Zhang, Dongke

AU - Atkin, Rob

PY - 2019/2/15

Y1 - 2019/2/15

N2 - Asphaltenes, which comprise polycyclic aromatic hydrocarbon cores with attached short aliphatic side chains, are the most polar fraction of crude oils. Asphaltenes are prone to precipitation, which requires expensive cleaning procedures using solvents like toluene or xylene. The toxicity and high vapour pressures of toluene and xylene means there is an urgent need for new liquids that are able to dissolve or suspend asphaltenes but are less environmentally problematic. This study reports treatment results of asphaltenes with 16 different ionic liquids covering three different types of cation charge groups, namely, cholinium, imidazolium and phosphonium with a wide variety of anions. The two oil-miscible ionic liquids, trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylphentyl)phosphinate and trihexyl(tetradecyl)phosphonium bis(2-ethylhexyl)phosphate, solubilised or suspended a significant fraction of raw asphaltenes. Elemental analysis, TGA and FTIR revealed that asphaltenes recovered from these ionic liquids had increased aliphatic and oxygen content compared to the raw material, and decomposed at lower temperatures during TGA test. The relative hydrophobicity of the ionic liquid is the major factor controlling the asphaltene mass in the ionic liquid, followed by the strength of interactions between ionic liquid and asphaltene alkyl groups. These findings provide a platform for the development of new ionic liquid based cleaners for asphaltene deposits.

AB - Asphaltenes, which comprise polycyclic aromatic hydrocarbon cores with attached short aliphatic side chains, are the most polar fraction of crude oils. Asphaltenes are prone to precipitation, which requires expensive cleaning procedures using solvents like toluene or xylene. The toxicity and high vapour pressures of toluene and xylene means there is an urgent need for new liquids that are able to dissolve or suspend asphaltenes but are less environmentally problematic. This study reports treatment results of asphaltenes with 16 different ionic liquids covering three different types of cation charge groups, namely, cholinium, imidazolium and phosphonium with a wide variety of anions. The two oil-miscible ionic liquids, trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylphentyl)phosphinate and trihexyl(tetradecyl)phosphonium bis(2-ethylhexyl)phosphate, solubilised or suspended a significant fraction of raw asphaltenes. Elemental analysis, TGA and FTIR revealed that asphaltenes recovered from these ionic liquids had increased aliphatic and oxygen content compared to the raw material, and decomposed at lower temperatures during TGA test. The relative hydrophobicity of the ionic liquid is the major factor controlling the asphaltene mass in the ionic liquid, followed by the strength of interactions between ionic liquid and asphaltene alkyl groups. These findings provide a platform for the development of new ionic liquid based cleaners for asphaltene deposits.

KW - Asphaltenes

KW - Ionic liquids

KW - Suspension

KW - Dissolution

KW - Aggregation

KW - ALKYLBENZENE-DERIVED AMPHIPHILES

KW - COAL-LIQUEFACTION RESIDUE

KW - ATOMIC-FORCE MICROSCOPY

KW - CRUDE-OIL

KW - MAGNETIC-RESONANCE

KW - ATHABASCA BITUMEN

KW - VACUUM RESIDUES

KW - SPECTROSCOPY

KW - PETROLEUM

KW - MOLECULES

U2 - 10.1016/j.fuel.2018.10.070

DO - 10.1016/j.fuel.2018.10.070

M3 - Article

VL - 238

SP - 129

EP - 138

JO - Fuel

JF - Fuel

SN - 0016-2361

ER -