Improving Physical Absorption of Carbon Dioxide by Ionic Liquid Dispersion

Abstract

An ionic liquid (IL), 1‐butylimidazole hexafluoride phosphate [bmim]PF4, was dispersed in surfactant solution to form an IL‐in‐water emulsion. Physical absorption of CO2 was carried out in this emulsion system. Absorption rates of CO2 under different operating conditions were obtained by experimental measurements. CO2 concentrations in the bulk of absorbent and the local volumetric mass transfer coefficients of the liquid phase were calculated by model calculation. Experimental results indicate that the dispersed IL droplets in aqueous solution can significantly enhance CO2 mass transfer at the gas‐liquid interface. This phenomenon can be ascribed to the increase of mass transfer driving force and local volumetric mass transfer coefficient. The shuttle effect and hydrodynamic effect proved to play important roles for CO2 absorption improved by dispersed IL.

Mass‐transfer rate enhancement for CO2 separation by ionic liquids: Theoretical study on the mechanism

“…27 Following this assumption, the activity coefficient of CO 2 in an IL equals to one, and the activity of CO 2 …”

“…The chemical potential of CO 2 in the gas phase equals to that in the liquid phase at equilibrium. Assuming that the average amount of absorbed CO 2 in IL (x CO2 ,b ) was a boundary condition for the diffusion layer as shown in Figure 1 and considering that the nonideal behavior of CO 2 in IL was negligible, 27 the concentration of CO 2 in IL can be described as those shown in Figure 1, where x CO 2 ;e , x CO 2 ;i , and x CO 2 ;b represent the concentrations of CO 2 at equilibrium, in the interface and on the boundary of the diffusion layer. The overall resistance (1/k l ) of the process can be considered as the summation of the resistances from the reaction layer and diffusion layer as described in Eq.…”

Enhancement of Carbon Dioxide Mass Transfer Coupling the Synthesis of Calcium Carbonate Fine Particles by (Ionic Liquid)-Emulsion Liquid Membrane

“…Therefore, the result indicates that the mass transfer rate is enhanced by the dispersion. The enhancement mechanism by dispersion has been discussed in our previous literature, [30,31] namely, the hydrodynamic effect and the shuttle effect. Meanwhile, the amount of CO 2 absorption amount in Figure 4.…”

“…Our group has researched the enhancement of CO 2 in the gas-liquid interface by IL-emulsion and proved that IL-emulsion does enhance the absorption rate of CO 2 . [30,31] Based on our previous experiments, it can be predicted that the presence of IL-ELM may enhance CO 2 mass transfer.…”

Enhancement of CO2 Absorption into K2CO3 Solution by Cyclohexane in a High-Shear Reactor

“…Gas–liquid–liquid (G–L–L) systems are commonly used in chemical and biochemical engineering, , and it is found that addition of the second liquid phase can enhance mass transfer between gas and liquid. − Zhang et al investigated CO 2 absorption in the G–L–L system in a stirred-tank reactor, and the results indicated that the volumetric mass-transfer coefficient increased when a second dispersed liquid phase was added and stirring speed markedly affected the volumetric mass-transfer coefficient. Liu et al . used an ionic liquid (IL), 1-butylimidazole hexafluoride phosphate, as dispersed phase to form an IL-in-water emulsion as CO 2 absorbent.…”