Feasible ionic liquid-amine hybrid solvents for carbon dioxide capture

Ionic liquid (IL)-amine hybrid solvents have been proved to be an energy-saving system for CO2 capture. Lack of experimental information on the diffusivity and heat of CO2 absorption in IL-amine hybrid solvents hampers the wide application of IL in CO2 capture. In this work, the effects of IL on absorption rate, solubility, diffusivity and heat of CO2 absorption in feasible hybrids of 1-butyl-3-methyl-imidazolium nitrate ([Bmim][NO3]) and monoethanolamine (MEA) have been elaborated using weight method, vapor liquid equilibrium and calorimetric measurement. The results showed that the addition of IL slightly decreases CO2 loading under atmospheric pressure. Based on the measured solubility and calorimeter results, IL is beneficial to improve the physical absorption of CO2 and reduce the heat of absorption in IL-amine hybrids. The diffusivity of CO2 can be maintained at an acceptable level by controlling the concentration of IL. Considering CO2 capacity, kinetics and heat of absorption, the hybrids of 30% MEA + 10% [Bmim][NO3] + 60% H2O were recommended. Our work gives the meaningful insights on designing novel IL-amine hybrids for CO2 capture.