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. © 2018 American Institute of Chemical Engineers AIChE J , 65: 230–238, 2019