Inhibition Effect of Synthesized Ionic Liquids on Hydrate Formation: A Kinetic and Thermodynamic Study

In recent years, ionic liquids (ILs) are considered as potential thermodynamic and kinetic inhibitors of gas hydrate formation because of their unique molecular properties. In the present study, the effect of two ILs, namely, 1-methyl-3-octylimidazolium tetrafluoroborate (C(8)mimBF(4)) and 1-methyl-3-dodecylimidazolium tetrafluoroborate (C(12)mimBF(4)), on the formation and dissociation of hydrates thermodynamically and kinetically has been investigated. The influence of C(8)mimBF(4) IL on induction time, hydrate formation rate, gas consumption, and water to hydrate and gas to hydrate conversion and enthalpy are investigated, and all the results are compared with a pure water system. The study reveals that the performance of IL solutions in hydrate inhibition is effective and has the ability to prevent the formation of hydrates both thermodynamically and kinetically. The results show that ILs significantly increase the induction time and the initial hydrate formation rate compared to the pure water system. The hydrate inhibition performance of ILs increases with increasing alkyl chain length, as the surface adsorption capacity on the hydrate crystal surface increases with enhanced alkyl chain length. The induction time of hydrate formation in the presence of 1 wt % of C8 and C12 ILs is 0.96 and 1.23 h, respectively. The investigated ILs with imidazolium-based cations have a higher impact on reducing the formation rate and rate constant in comparison with pure water.

Automated summary

This study investigates the effect of two ionic liquids on the formation and dissociation of gas hydrates and finds that they are effective inhibitors. The inhibition performance of the ionic liquids increases with increasing alkyl chain length.