Designing amino‐based ionic liquids for improved carbon capture: One amine binds two CO₂

Abstract

Generally, amine group captures CO 2 according to 2:1 or 1:1 stoichiometry. Here, we report a kind of improved carbon capture using amino-functionalized ionic liquids (ILs) through 1:2 stoichiometry. A serial of amino-functionalized ILs various with basicity and steric hindrance of anion were designed, prepared, and applied in CO 2 capture. Through a combination of absorption experiment, quantum chemical calculation, spectroscopic investigation and calorimetric method, the results indicated that one amine group could bind two CO 2 through proton transfer (PT) process and intramolecular hydrogen bond formation, which leading to enhanced capacity that breaks through equimolar. The basicity and steric hindrance of anion play a significant role in promoting amine group to capture two CO 2 . [P 66614 ] 2 [Asp] with dual anion was further designed and synthesized to promote PT process, which showed high capacity of 1.96 mol/mol IL at 30 C and 1 atm as well as excellent reversibility.

New chemistry for enhanced carbon capture: beyond ammonium carbamates

“…39 d) Proposed absorption mechanism for an IL with an aspartate dianion. 40 In all cases, the corresponding cations are omitted for clarity.…”

Basic ionic liquids for catalysis: the road to greater stability

“…Ionic liquids with amine groups generally absorb CO 2 in a 2:1 or 1:1 molar ratio by forming a carbamate. Luo et al 91 have prepared ionic liquids with amino functionalised anions which can capture CO 2 in almost a 1:2 ratio. (Figure 18).…”

Cholinium amino acid-based ionic liquids

“…Other authors have reported larger absorption capacity up to 1:2 M ratio. In a first work (Luo et al 2019 ), a set AAILs with different basicity and steric hindrance was tested. It was found that the di-anion of a doubly deprotonated AA such as Asp showed a very high absorption capacity of 1.96 mol/mol IL at 30 °C and 1 atm.…”