Selection of a suitable ZIF-8/ionic liquid (IL) based composite for selective CO₂ capture: the role of anions at the interface

Abstract

The interfacial stability of hydrophilic/hydrophobic IL incorporated ZIF-8 is identified and the CO2 selectivity depends on the fluorinated anions in the IL.

Porous Ionic Liquids: Structure, Stability, and Gas Absorption Mechanisms

“…The total energy changes associated with the transfer of the dissolved gas from the ionic liquid to the MOF, Δ tr H , were also calculated from the molecular simulations, [ 41 ] using the extrapolations to infinite dilution, as depicted in Figure S14, Supporting Information. The calculated transfer energies are −29.8 kJ mol −1 and −107.9 kJ mol −1 for CH 4 and CO 2 , respectively.…”

“…[37][38][39] The isosteric heat of adsorption was found to be in the range −13 to −16 kJ mol −1 for CO 2 and ≈−13 kJ mol −1 for CH 4 in the temperature range 273-348 K. [37][38][39] Interestingly enough, the CO 2 adsorption process is the slowest, while the fastest absorption is that of CH 4 [40] as will be discussed below. The total energy changes associated with the transfer of the dissolved gas from the ionic liquid to the MOF, Δ tr H, were also calculated from the molecular simulations, [41] using the extrapolations to infinite dilution, as depicted in Figure S14, Supporting Information. The calculated transfer energies are −29.8 kJ mol −1 and −107.9 kJ mol −1 for CH 4 and CO 2 , respectively.…”

Mechanisms behind high CO2/CH4 selectivity using ZIF-8 metal organic frameworks with encapsulated ionic liquids: A computational study

“…Moreover, Mohamed et al [31] investigated the effect of distribution, composition and types of IL pairs on CO2/CH4 selectivity, and Thomas et al [32] studied the effect of anion types on IL@ZIF-8 selectivity by DFT and GCMC simulations. The authors found that the hydrophobic fluorinated anions ([BF4] -, [Tf2N]and [PF6] -) gives a much better selectivity than hydrophilic non-fluorinated anions.…”

“…It is suggested that the presence of IL molecules in MOF cages narrows the effective CO2/CH4 passage, resulting in tailored molecular sieves [27,33]. Some other studies attributed the selectivity enhancement to IL anion types [32] and generated adsorption sites [28]. It appears that the detailed mechanisms regarding aperture configuration variation still remains indistinct.…”

Research progress in metal–organic frameworks (MOFs) in CO2capture from post-combustion coal-fired flue gas: characteristics, preparation, modification and applications

“…17a. Thomas et al 127 used DFT methods to select [BMIM] + with a series of anions and analyzed the influence of ionic liquids (ILs) encapsulated in the ZIF-8 channel structure on the selective capture and separation of CO 2 . It was found that the fluoride ion content in the anion played a major role in the affinity of the composite material to CO 2 molecules.…”