Water Vapour Promotes CO2 Transport in Poly(ionic liquid)/Ionic Liquid-Based Thin-Film Composite Membranes Containing Zinc Salt for Flue Gas Treatment

Abstract

A poly(ionic-liquid) (PIL) matrix can be altered by incorporating additives that will disrupt the polymer chain packing, such as an ionic liquid (IL) and inorganic salts to boost their exploitation as materials for membrane production to be used in CO2 capture. Herein, potential of PIL/IL/salt blends is investigated on the example of poly(diallyldimethyl ammonium) bis(trifluoromethylsulfonyl)imide (P[DADMA][Tf2N]) with N-butyl-N-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide ([Pyrr14][Tf2N]) and zinc di-bis(trifluoromethylsulfonyl)imide (Zn[Tf2N]2). Composite material with IL and a higher amount of Zn2+ showed an increase in the equilibrium CO2 sorption capacity to 2.77 cm3 (STP)cm −3 bar−1. Prepared blends were successfully processed into thick, dense membranes and thin-film composite membranes. Their CO2 separation efficiency was determined using ideal and mixed-gas feed (vol% CO2 = 50 , dry and with 90% relative humidity). The dominant role of solubility in the transport mechanism is confirmed by combining direct gravimetric sorption measurements and indirect estimations from time-lag experiments. The maximum incorporated amount of Zn2+ salts increased equilibrium solubility selectivity by at least 50% in comparison to the parent PIL. All materials showed increased CO2 permeance values by at least 30% in dry conditions, and 60% in humidified conditions when compared to the parent PIL; the performance of pure PIL remained unchanged upon addition of water vapor to the feed stream. Mixed-gas selectivities for all materials rose by 10% in humidified conditions when compared to dry feed experiments. Our results confirm that the addition of IL improves the performance of PIL-based composites due to lower stiffness of the membrane matrix. The addition of Zn2+-based salt had a marginal effect on CO2 separation efficiency, suggesting that the cation participates in the facilitated transport of CO2.

Micro and Nanoporous Membrane Platforms for Carbon Neutrality: Membrane Gas Separation Prospects

“…[224] The properties of PIL membranes can be improved by blending free ILs with PILs, forming poly(IL)-IL (PIL-IL)based membranes. Nikolaeva et al [225] altered the matrix of a PIL by incorporating additives (ILs and inorganic salts) that disrupt the polymer-chain packing, making them more suitable for membrane fabrication. They prepared PIL/IL/salt blends and processed them into thick and thin-film composite membranes for CO 2 separation.…”

Recent Advances in Poly(Ionic Liquid)-Based Membranes for CO2 Separation

“…In 2020, Nikolaeva et al [ 46 ] prepared PIL-IL-inorganic particle mixed matrix membranes by blending the PIL poly(diallyldimethyl ammonium) bis(trifluoromethylsulfonyl)imide (P[DADMA][Tf 2 N]) with the IL N-butyl-N-methyl pyrrolidinium bis(trifluoromethylsulfonyl)imide ([Pyrr 14 ][Tf 2 N]) and with zinc di-bis(trifluoromethylsulfonyl)imide (Zn[Tf 2 N] 2 ). Two different mixed matrix membranes PIL/IL/Zn[Tf2N] 2 were prepared with weight ratios of 9:6:1 (P9IL6Zn1) and 9:6:9 (P9IL6Zn9), and the gas separation performance of these was compared with the performance of neat PIL membranes (P9IL0Zn0) and composite PIL/IL membranes (P9IL6Zn0).…”

“…Structural and morphological studies of PIL-based membranes for CO 2 separation have been so far very much limited to the use of some relatively common techniques such as SEM [ 28 , 29 , 38 , 39 , 42 , 44 , 46 ] and TEM [ 41 ], as well as some WAXS [ 37 , 42 ], with their associated limitations. Furthermore, the reports on the use of small angle X-ray scattering (SAXS) are also still very scarce [ 38 ].…”

“… Robeson plots of PIL-based membranes for the: ( a ) CO 2 /N 2 separation; ( b ) CO 2 /CH 4 separation; and ( c ) CO 2 /H 2 separation. The indicated works correspond to the following references: Tomé et al (2016) [ 15 ]; Nikolaeva et al (2017) [ 28 ]; Nikolaeva et al (2018) [ 29 ]; Yin et al (2020) [ 30 ]; Tomé et al (2017) [ 31 ]; Teodoro et al (2018) [ 32 ]; Tomé et al (2018) [ 33 ]; Gouveia et al (2018) [ 34 ]; Gouveia et al (2021) [ 35 ]; Gouveia et al (2020) [ 36 ]; Kammakakam et al (2020) [ 37 ]; Vijayakumar et al (2021) [ 38 ]; Zhang et al (2017) [ 39 ]; Nellepalli et al (2019) [ 40 ]; Wang et al (2021) [ 41 ]; Ravula et al (2022) [ 42 ]; Dunn et al (2019) [ 43 ]; Nabais et al (2019) [ 44 ]; Sampaio et al (2020) [ 45 ] and Nikolaeva et al (2020) [ 46 ]. …”

Off-Design Operation of Conventional and Phase-Change CO2 Capture Solvents and Mixtures: A Systematic Assessment Approach

“…The development of efficient CO 2 abatement systems is widely pursued as a means of mitigating the detrimental effects of global warming [1]. Currently, intense research efforts are focusing on CO 2 capture technologies, such as membrane processes [2], adsorption systems [3], and materials- [4,5] and solvent-based absorption/desorption processes [6]. The latter represents a technology with significant potential, which has been demonstrated even in large-scale plants [7,8].…”