Ionic liquids for the inhibition of gas hydrates. A review

• Main Authors: Ul Haq, I., Qasim, A., Lal, B., Zaini, D.B., Foo, K.S., Mubashir, M., Khoo, K.S., Vo, D.-V.N., Leroy, E., Show, P.L.
• Format: Article
• Published: Springer Science and Business Media Deutschland GmbH 2022
• Online Access: https://www.scopus.com/inward/record.uri?eid=2-s2.0-85122666706&doi=10.1007%2fs10311-021-01359-9&partnerID=40&md5=c0867c7b9cf0654e5a8957773fd50f40; http://eprints.utp.edu.my/28966/

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. © 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.