Ionic liquids for the inhibition of gas hydrates. A review

Ihtisham Ul Haq, Ali Qasim, Bhajan Lal, Dzulkarnain B. Zaini, Khor Siak Foo, Muhammad Mubashir, Kuan Shiong Khoo, Dai Viet N. Vo, Eric Leroy, Pau Loke Show

Research output: Contribution to journalReview articlepeer-review

19 Scopus citations


The formation of gas hydrates is a major issue during the operation of oil and gas pipelines, because gas hydrates cause plugging, thereby disrupting the normal oil and gas flows. A solution is to inject gas hydrate inhibitors such as ionic liquids. Contrary to classical inhibitors, ionic liquids act both as thermodynamic inhibitors and hydrate inhibitors, and as anti-agglomerates. Imidazolium-based ionic liquids have been found efficient for the inhibition of CO2 and CH4 hydrates. For CO2 gas hydrates, N-ethyl-N-methylmorpholinium bromide showed an average depression temperature of 1.72 K at 10 wt% concentration. The induction time of 1-ethyl-3-methyl imidazolium bromide is 36.3 h for CO2 hydrates at 1 wt% concentration. For CH4 hydrates, 1-ethyl-3-methyl-imidazolium chloride showed average depression temperature of 4.80 K at 40 wt%. For mixed gas hydrates of CO2 and CH4, only quaternary ammonium salts have been studied. Tetramethyl ammonium hydroxide shifted the hydrate liquid vapour equilibrium to 1.56 K at 10 wt%, while tetrabutylammonium hydroxide showed an induction time of 0.74 h at 1 wt% concentration.

Original languageBritish English
Pages (from-to)2165-2188
Number of pages24
JournalEnvironmental Chemistry Letters
Issue number3
StatePublished - Jun 2022


  • Flow assurance
  • Gas hydrates
  • Ionic liquids
  • Kinetic hydrate inhibitors
  • Thermodynamic hydrate inhibitors


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