Effect of the amino-group densities of functionalized ionic liquids on the facilitated transport properties for CO2 separation

Abstract

Amino acid ionic liquids (AAILs) composed of different sizes and numbers of amino groups, including tetrabutylammonium glycinate, tetramethylammonium glycinate, and 1,1,1-trimethylhydrazinium glycinate, were synthesized as CO 2 carriers for facilitated transport membranes. The physical properties of the fabricated AAILs, such as density, viscosity, and N 2 and CO 2 absorption capacities, were measured, and the fractional free volume was calculated using molecular dynamics (MD) simulations. The results showed that the molar and fractional free volumes decreased with decreasing AAIL size, which caused increased CO 2 absorption and decreased N 2 absorption. In addition, the CO 2 absorption increased with higher numbers of amino groups in the AAILs. The gas permeation properties of facilitated transport membranes containing the synthesized AAILs were investigated. The small AAILs with two amino groups showed better CO 2 permeability and N 2 barrier properties under humid conditions. We propose that ionic liquids optimized as CO 2 carriers for facilitated transport membranes under humid conditions should have high amino-group density, which could be realized by decreasing the molecular size and introducing more amino groups in the molecule.

Effects of Water Concentration on the Free Volume of Amino Acid Ionic Liquids Investigated by Molecular Dynamics Simulations

“…Therefore, AAILs with low viscosity (i.e., high diffusion coefficient) and high CO 2 absorption capacity (CO 2 carrier complex reaction) can lead to high CO 2 permeability. Furthermore, according to previous results, 25b FV significantly influences the transport properties (solubility and permeability of gases) of AAIL-based FTMs, thereby attaining high CO 2 26 The aim of the present study is to investigate the effect of water molecules on cation−anion interactions and the statistical and dynamics properties of the above-mentioned ILs.…”

“…The diffusion coefficient of [aN 111 ] increased in the presence of water owing to the favorable interaction between the additional amine group present in the cation and water, thereby facilitating the diffusion of the cation and anion. 26 In general, for hydrophilic ILs, the presence of water molecules was found to decrease cation−anion Coulombic interaction energies, which is reflected in faster diffusion of ions. The diffusion coefficient for bulk water at 298 K is 5.43 × 10 −7 cm 2 /s that is greater than the experimentally determined value (2.8 × 10 −7 cm 2 /s) 43 system, the diffusion coefficient was high.…”

Ionic Liquids: Potential Materials for Carbon Dioxide Capture and Utilization

“…In equimolar mechanism, one mole of amine captures one mole of CO 2 and stabilizes the product as carbamic acid (Kasahara et al, 2016). Various studies have claimed multimolar absorption in ILs because of the presence of stabilizing group in the vicinity of NH 2 -moiety of the amine (Luo et al, 2014).…”

Widening CO2-facilitated transport passageways in SPEEK matrix using polymer brushes functionalized double-shelled organic submicrocapsules for efficient gas separation

“…The CO 2 permeability in Fig. 12(a) facilitated equation as reported [27,[57][58][59], and CO 2 diffusion coefficient (D A ) and diffusion coefficient of CO 2 -carrier complex (D AC ) contributing to the total diffusion coefficient are obtained by facilitated equation (4) and calculated equation parameters are listed ( Table 2). …”

“…show relatively high permeability and selectivity [27][28][29][30]. For CO 2 separation, the feed gas system is often moist [31][32][33][34].…”