Use of 1-butyl-3-methylimidazolium-based ionic liquids as methane hydrate inhibitors at high pressure conditions

The performance of 1-Butyl-3-methylimidazolium chloride ([BMIM][Cl]) and 1-Butyl-3-methyl-imidazolium bromide ([BMIM][Br]) as methane hydrate inhibitors is evaluated in this work. New hydrate dissociation data were obtained through high-pressure calorimetry for aqueous solutions with inhibitor mole fractions of 1.0%, 5.0%, 10.0%, and 15.0% and pressures from 9.6 to 100 MPa. Challenging situations from the experimental point of view were also explored. These ionic liquids are known to be both kinetic and thermodynamic inhibitors, but they promote hydrate growth at mole fractions of 1% and 5% in the pressure range studied. The effectiveness of these ionic liquids as thermodynamic inhibitors at high pressures is compared to that of methanol, a commercial inhibitor commonly used in the oil and gas industry. [BMIM][Cl] is more effective than [BMIM][Br] and methanol, considering equimolar aqueous solutions, even though methanol is more effective for solutions with the same mass fraction. (C) 2019 Elsevier Ltd. All rights reserved.