Decreasing the Viscosity in CO2 Capture by Amino-Functionalized Ionic Liquids through the Formation of Intramolecular Hydrogen Bond.

A strategy for decreasing the viscosity variation in the process of CO2 capture by amino-functionalized ionic liquids (ILs) through the formation of intramolecular hydrogen bond was reported. Different with the dramatic increase in viscosity during CO2 uptake by traditional amino-functionalized ILs, slight increase or even decrease in viscosity was achieved through introducing a N or O atom as hydrogen acceptor into amino-functionalized anion, which could stabilize the active hydrogen of produced carbamic acid. Quantum chemical calculations and spectroscopic investigations demonstrated that the formation of intramolecular hydrogen bond between introduced hydrogen acceptor and carbamic acid was the key to avoid the dramatic increase in viscosity during the capture of CO2 by these amino-functionalized ILs.

Efficient and Energy-Saving CO2 Capture through the Entropic Effect Induced by the Intermolecular Hydrogen Bonding in Anion-Functionalized Ionic Liquids.

A strategy for improving the capture of CO2 was developed through the entropic effect by tuning the geometric construction of anion-functionalized ionic liquids. Several kinds of anion-functionalized ionic liquids with the amino group at the para or ortho position were designed and applied for the capture of CO2, which indicates that the former exhibited both higher capacity and lower enthalpy, resulting in the efficient and energy-saving CO2 capture. Viscosity measurements, spectroscopic investigations, and quantum chemical calculations showed that such a unique behavior originated from the entropic effect, which was induced by the intermolecular hydrogen bonding in these ionic liquids. The entropic control for gas separation developed by this work provides an efficient strategy to both increased capacity and reduced enthalpy.