Kinetic Effects of Ionic Liquids on Methane Hydrate

The kinetic effects of several kinds of ionic liquids (ILs) on the formation of methane hydrate were experimentally investigated on both the macroscale and microscale levels. These ILs were 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm]-BF4), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm]-BF4), 1-butyl-3-methylimidazolium iodide ([BMIm]-I), and N-butyl-N-methylpyrrolidinium tetrafluoroborate ([Py14]-BF4). Formation temperature, max subcooling, induction time, and growth rate of methane gas hydrates were used to evaluate the kinetic effects of ionic liquids in a high-pressure cell and flow loop. As evaluated from the indicator of the formation temperature in the high-pressure cell, the sequence of inhibition performance of ILs was as follows: pure water < 1 wt % [EMIm]-BF4 < 1 wt % PVP < 1 wt % [BMIm]-I < 1 wt % [BMIm]-BF4 < 1 wt % [Py14]-BF4. ILs could not slow the growth rates of methane hydrate effectively and even promote the gas consumption rates irrespective of in a high-pressure cell or flow loop. RXRD spectra showed that ILs could not change the structure of methane hydrate. Cryo-scanning electron microscopy images showed that there was a porous texture of methane hydrate containing ILs. Raman spectra showed that ILs interact with the cages of methane hydrate.