New‐Generation Carbon‐Capture Ionic Liquids Regulated by Metal‐Ion Coordination

Abstract

Development of efficient carbon capture-and-release technologies with minimal energy input is a long-term challenge in mitigating CO 2 emissions, especially via CO 2 chemisorption driven by engineered chemical bond construction. Herein, taking advantage of the structural diversity of ionic liquids (ILs) in tuning their physical and chemical properties, precise reaction energy regulation of CO 2 chemisorption was demonstrated deploying metal-ion-amino-based ionic liquids (MAILs) as absorbents. The coordination ability of different metal sites (Cu, Zn, Co, Ni, and Mg) to amines was harnessed to achieve fine-tuning on stability constants of the metal ion-amine complexes, acting as the corresponding cations in the construction of diverse ILs coupled with CO 2 -philic anions. The asafforded MAILs exhibited efficient and controllable CO 2 release behavior with great reduction in energy input and minimal sacrifice on CO 2 uptake capacity. This coordination-regulated approach offers new prospects for the development of ILsbased systems and beyond towards energy-efficient carbon capture technologies.

Reviewing and screening ionic liquids and deep eutectic solvents for effective CO2 capture

“…The absorption capacity (mol/kg) decreased in the order of [C 5 ] < [C 6 ] < [C 7 ], and [EHA][C 7 ] showed the highest absorption capacity (∼3.0 mol/kg at 29 bar and room temperature). Taking the advantage of metal ion coordination, Suo et al (2022) synthesized metal-ion-amino-based IL using metal salts {[M(OctNH 2 ) 4 ][NTf 2 ] 2 , M = Co, Cu, Ni, Zn, and Mg}. The CO 2 absorption capacity (mol/kg) followed the order of [Li(OctNH 2 ) 4 ][NTf 2 ] 2 > [Mg (DecNH 2 ) 4 ][NTf 2 ] 2 ≈ [Mg(OctNH 2 ) 4 ][NTf 2 ] 2 > [Ni(OctNH 2 ) 4 ][NTf 2 ] 2 > [Ni(DecNH 2 ) 4 ][NTf 2 ] 2 > [Co(OctNH 2 ) 4 ][NTf 2 ] 2 > [Zn(OctNH 2 ) 4 ][NTf 2 ] 2 > [CuMg(DecNH 2 ) 4 ][NTf 2 ] 2 > [Cu(OctNH 2 ) 4 ][NTf 2 ] 2 > [CuZnNiMg(DecNH 2 ) 4 ][NTf 2 ] 2 > [CuZn(DecNH 2 ) 4 ][NTf 2 ] 2 .…”

Microwave Regeneration and Thermal and Oxidative Stability of Imidazolium Cyanopyrrolide Ionic Liquid for Direct Air Capture of Carbon Dioxide

“…[26,27] Recently, bottomup approaches involving metal-ion coordinated amines as reactive CO 2 capture agents are demonstrated to lower the energy requirement and increase sorbent stability for regeneration. [28] With the increasing availability of renewable energy sources, alternative regeneration approaches that do not rely on thermal energy from fossil-fuel burning is gaining interest. There have been few reports on the microwave-based regeneration of conventional aqueous amines [29,30] and solid sorbents.…”

“…Regeneration of sorbents has traditionally relied on temperature‐swing operations and the availability of thermal energy to desorb the CO 2 and recycle the sorbent [26,27] . Recently, bottom‐up approaches involving metal‐ion coordinated amines as reactive CO 2 capture agents are demonstrated to lower the energy requirement and increase sorbent stability for regeneration [28] . With the increasing availability of renewable energy sources, alternative regeneration approaches that do not rely on thermal energy from fossil‐fuel burning is gaining interest.…”

Tuning Functionalized Ionic Liquids for CO2 Capture

“…Their results showed that CO 2 capacity of polyamine-based ILs increased when [Li(TTEG)][Tf 2 N] or [Li(TEG)][Tf 2 N] was added, and CO 2 capacity of [Li(TEPA)][Tf 2 N]/[Li(TEG)][Tf 2 N] (weight ratio is 1:2) decreased from 2.05 to 0.83 mol per CO 2 mol IL at 80 °C when CO 2 concentration was reduced from 100 vol.% to 380 ppm. Recently, Yang, Xing, and Dai et al [ 37 ] reported the tuning of stability constants of metal-amine complexes for efficient CO 2 desorption.…”