Efficient and Reversible Chemisorption of Carbon Dioxide with Dianionic-Functionalized Ionic Liquid-Based Solvents

Developing carbon dioxide (CO2) capture technologies has caused worldwide interest because of the baneful influence of CO2 on climate change as a main greenhouse gas. Ionic liquids (ILs) are considered as potential absorbents for CO2 capture because of their unique properties compared with current amine-based solvents. In this work, new dianionic-functionalized IL-based solvents, bi(1,8-diazabicyclo[5.4.0]undec-7-ene) dimethylhydantoin/ethylene glycol ([(DBUH)2][Dhyd]/EG), were designed and prepared for efficient and reversible chemisorption of CO2. Among the absorbents, [(DBUH)2][Dhyd]/EG with a mass ratio of 5:5 exhibited not only a high CO2 absorption capacity of 0.11 g CO2/g absorbent at 20 °C and 0.10 MPa but also good recyclability. Spectroscopic characterizations and simulation calculations confirmed that the superior CO2 capacity may be attributed to the simultaneous reaction of CO2 with both the [Dhyd]2– anion and deprotonated EG. The excellent CO2 absorption and regeneration performance imply that [(DBUH)2][Dhyd]/EG solvents may have great industrial application potentials.