Amine‐Functionalized Amino Acid‐based Ionic Liquids as Efficient and High‐Capacity Absorbents for CO2. Issue 3 (20th February 2014)

• Record Type: Journal Article
• Authors: Saravanamurugan, Shunmugavel; Kunov‐Kruse, Andreas J.; Fehrmann, Rasmus; Riisager, Anders
• Is Part Of: ChemSusChem. Volume 7:Issue 3(2014:Mar.)
• Page Start: 897
• Page End: 902
• Publication Date: 2014-02-20
• Subjects: Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201300691
• Languages: English
• ISSNs: 1864-5631

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Ionic liquids (ILs) comprised of ammonium cations and anions of naturally occurring amino acids containing an additional amine group (e.g., lysine, histidine, asparagine, and glutamine) were examined as high‐capacity absorbents for CO₂. An absorption capacity of 2.1 mol CO₂ per mol of IL (3.5 mol CO₂ per kg IL, 13.1 wt % CO₂) was measured for [N₆₆₆₁₄][Lys] at ambient temperature and about 1 mol CO₂ per mol of IL at 80 °C (under 1 bar of CO₂). This demonstrated that desorption is possible under CO₂‐rich conditions by temperature‐swing absorption; three consecutive sorption cycles were performed with the IL. The mechanistic and kinetic study of the absorption process was further substantiated by NMR spectroscopy and in situ attenuated total reflectance FTIR for [N₆₆₆₁₄][Lys] and the homologous phosphonium‐based IL [P₆₆₆₁₄][Lys]. This study revealed that carbamic acid was formed with CO₂ in both ILs by chemisorption; however, the amino acid–carboxyl groups on the anion played an important—but different—catalytic role for the sorption kinetics in the two ILs. The origin of the cationic effect is speculated to be correlated with the strength of the ion interactions in the two ILs.</p> </abstract>