Enhanced CO₂ Separation Selectivity in Oligo(ethylene glycol) Functionalized Room-Temperature Ionic Liquids

Abstract

Novel imidazolium-based room-temperature ionic liquids (RTILs) with one, two, or three oligo(ethylene glycol) substituents were synthesized. Solubilities and ideal solubility selectivities of CO 2 , N 2 , and CH 4 at low pressure (1 atm) in these RTILs were determined using a pressure decay technique. Comparison to corresponding alkyl analogues of these RTILs reveals similar levels of CO 2 solubility but lower solubilities of N 2 and CH 4 . As a consequence, RTILs with oligo(ethylene glycol) substituents were observed to have 30-75% higher ideal solubility selectivities for CO 2 /N 2 and CO 2 /CH 4 .

Tuning the Physicochemical Properties of Diverse Phenolic Ionic Liquids for Equimolar CO2 Capture by the Substituent on the Anion

“…Many research groups have conducted outstanding research on the physical absorption of CO 2 in ILs using both experimental and theoretical methods. [26][27][28][29][30] Their results have shown that CO 2 is very soluble in ILs, especially at high pressures. However, the physical absorption of CO 2 in ILs has some way to go because of their low capacity under atmospheric pressure.…”

CO2 separation applying ionic liquid mixtures: the effect of mixing different anions on gas permeation through supported ionic liquid membranes

“…Other studies, also focused on imidazolium ILs, explored different structural variations of the cation in order to enhance CO 2 solubility and selectivity. [35][36][37] On the other hand, the performance of imidazolium-based ILs containing several different anions has also been evaluated. …”

Synthesis of poly(ethylene glycol) functionalized star-shaped tricationic imidazolium based ionic liquid

“…This compound was prepared according to literature procedures [53] . For example, into a round-bottom flask equipped with a magnetic stirring bar, NaH (60 mg, 2.5 mmol), and dry THF (10 mL) were charged.…”