Ionic liquids in carbon capture

[5] Beside that, ionic liquids have replaced the conventional volatile solvents in industry such as absorption of gases or extractive distillation.

Ionic liquids could follow a similar process to amine gas treating, where the CO2 is regenerated in the stripper using higher temperature.

Task-specific ionic liquids that employ chemisorption and physisorption are being developed in an attempt to increase the working capacity.

[6] Subsequently, they conducted precise measurements of CO2 solubility and successfully developed ionic liquids with the highest physical absorption capacity for CO2 to date.

[9] A primary concern with the use of ionic liquids for carbon capture is their high viscosity compared with that of commercial solvents.

The viscosity of an ionic liquid can vary significantly according to the type of anion and cation, the alkyl chain length, and the amount of water or other impurities in the solvent.

[11][12] Because these solvents can be “designed” and these properties chosen, developing ionic liquids with lowered viscosities is a current topic of research.

1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) is a room-temperature ionic liquid that was identified early on as a viable substitute for volatile organic solvents in liquid-liquid separations.

[13] Other [PF6]- and [BF4]- containing ionic liquids have been studied for their CO2 absorption properties, as well as 1-ethyl-3-methylimidazolium (EMIM) and unconventional cations like trihexyl(tetradecyl) phosphonium ([P66614]).

Additionally, the organic cations in ionic liquids can be "tuned" by changing chain lengths or by substituting radicals.

"[14] 1-butyl-3-propylamineimidazolium tetrafluoroborate was specifically developed for CO2 capture; it is designed to employ chemisorption to absorb CO2 and maintain efficiency under repeated absorption/regeneration cycles.