scholarly journals Tunning CO2 Separation Performance of Ionic Liquids through Asymmetric Anions

Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 413
Author(s):  
Bruna F. Soares ◽  
Daniil R. Nosov ◽  
José M. Pires ◽  
Andrey A. Tyutyunov ◽  
Elena I. Lozinskaya ◽  
...  

This work aims to explore the gas permeation performance of two newly-designed ionic liquids, [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2], in supported ionic liquid membranes (SILM) configuration, as another effort to provide an overall insight on the gas permeation performance of functionalized-ionic liquids with the [C2mim]+ cation. [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] single gas separation performance towards CO2, N2, and CH4 at T = 293 K and T = 308 K were measured using the time-lag method. Assessing the CO2 permeation results, [C2mim][CF3BF3] showed an undermined value of 710 Barrer at 293.15 K and 1 bar of feed pressure when compared to [C2mim][BF4], whereas for the [C2mim][CF3SO2C(CN)2] IL an unexpected CO2 permeability of 1095 Barrer was attained at the same experimental conditions, overcoming the results for the remaining ILs used for comparison. The prepared membranes exhibited diverse permselectivities, varying from 16.9 to 22.2 for CO2/CH4 and 37.0 to 44.4 for CO2/N2 gas pairs. The thermophysical properties of the [C2mim][CF3BF3] and [C2mim][CF3SO2C(CN)2] ILs were also determined in the range of T = 293.15 K up to T = 353.15 K at atmospheric pressure and compared with those for other ILs with the same cation and anion’s with similar chemical moieties.

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1388
Author(s):  
Kathryn E. O’Harra ◽  
Emily M. DeVriese ◽  
Erika M. Turflinger ◽  
Danielle M. Noll ◽  
Jason E. Bara

This work introduces a series of vinyl-imidazolium-based polyelectrolyte composites, which were structurally modified via impregnation with multivalent imidazolium-benzene ionic liquids (ILs) or crosslinked with novel cationic crosslinkers which possess internal imidazolium cations and vinylimidazolium cations at the periphery. A set of eight [C4vim][Tf2N]-based membranes were prepared via UV-initiated free radical polymerization, including four composites containing di-, tri-, tetra-, and hexa-imidazolium benzene ILs and four crosslinked derivatives which utilized tri- and tetra- vinylimidazolium benzene crosslinking agents. Structural and functional characterizations were performed, and pure gas permeation data were collected to better understand the effects of “free” ILs dispersed in the polymeric matrix versus integrated ionic crosslinks on the transport behaviors of these thin films. These imidazolium PIL:IL composites exhibited moderately high CO2 permeabilities (~20–40 Barrer), a 4–7× increase relative to corresponding neat PIL, with excellent selectivities against N2 or CH4. The addition of imidazolium-benzene fillers with increased imidazolium content were shown to correspondingly enhance CO2 solubility (di- < tri- < tetra- < hexa-), with the [C4vim][Tf2N]: [Hexa(Im+)Benz ][Tf2N] composite showing the highest CO2 permeability (PCO2 = 38.4 Barrer), while maintaining modest selectivities (αCO2/CH4 = 20.2, αCO2/N2 = 23.6). Additionally, these metrics were similarly improved with the integration of more ionic content bonded to the polymeric matrix; increased PCO2 with increased wt% of the tri- and tetra-vinylimidazolium benzene crosslinking agent was observed. This study demonstrates the intriguing interactions and effects of ionic additives or crosslinkers within a PIL matrix, revealing the potential for the tuning of the properties and transport behaviors of ionic polymers using ionic liquid-inspired small molecules.


2019 ◽  
Vol 6 (9) ◽  
pp. 190866 ◽  
Author(s):  
Lidia Martínez-Izquierdo ◽  
Magdalena Malankowska ◽  
Javier Sánchez-Laínez ◽  
Carlos Téllez ◽  
Joaquín Coronas

The present work is focused on the study of the effect that the casting solution concentration has on the morphology and gas separation performance of poly(ether- block -amide) copolymer membranes (Pebax ® MH 1657). With this aim, three different concentrations of Pebax ® MH 1657 in the casting solution (1, 3 and 5 wt%) were used to prepare dense membranes with a thickness of 40 µm. The morphology and thermal stability of all membranes were characterized by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, rotational viscometry and thermogravimetric analyses. An increase in crystallinity was notable when the amount of solvent in the Pebax ® MH 1657 solution was higher, mainly related to the polymer chains arrangement and the solvent evaporation time. Such characteristic seemed to play a key role in the thermal degradation of the membranes, confirming that the most crystalline materials tend to be thermally more stable than those with lower crystallinity. To study the influence of their morphology and operating temperature on the CO 2 separation, gas separation tests were conducted with the gas mixture CO 2 /N 2 . Results indicated that a compromise must be found between the amount of solvent used to prepare the membranes and the crystallinity, in order to reach the best gas separation performance. In this study, the best performance was achieved with the membrane prepared from a 3 wt% casting solution, reaching at 35°C and under a feed pressure of 3 bar, a CO 2 permeability of 110 Barrer and a CO 2 /N 2 selectivity of 36.


2013 ◽  
Vol 448-453 ◽  
pp. 765-770 ◽  
Author(s):  
Li Zhe Liang ◽  
Quan Gan ◽  
Paul Nancarrow

In recent years, the utilisation of ionic liquids supported on porous polymer membranes has been demonstrated to enhance gas separation performance by improving both permeability and selectivity for several industrially-relevant gas mixtures. However, the use of such supported ionic liquid membranes (SILMs) is normally not feasible at elevated process temperatures due to the resulting decrease in ionic liquid viscosity, which can lead to increased loss of ionic liquid from the membrane support during operation. In addition, many of the polymer membranes typically used in SILMs exhibit relatively poor mechanical and thermal stabilities at high temperatures. To overcome these problems associated with SILMs, thermally-stable composite ionic liquid and polymer membranes (CILPMs) have been fabricated in this study, thus exploiting the beneficial properties of ionic liquids for gas separation at elevated temperatures. Poly (pyromellitimide-co-4,4-oxydianiline) (PMDA-ODA PI) in combination with the ionic liquid, [C4mi [NTf2] were used to fabricate the CILPMs. A measurement rig was designed and built to determine permeabilities and selectivities of the CILPMs for H2, N2, CO, CO2 and CH4 over a range of pressures and temperatures. The fabricated CILPMs were shown to maintain excellent mechanical and thermal stability over a wide range of processing conditions. Temperature was shown to greatly affect both permeability and selectivity of the membranes, whilst pressure had less influence. The incorporation of [C4mi [NTf2] into the membranes was found to significantly increase CO2 permeation and, therefore, it is anticipated that these CILPMs hold significant potential for CO2 separation applications.


Membranes ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 693
Author(s):  
Fei Guo ◽  
Bingzhang Li ◽  
Rui Ding ◽  
Dongsheng Li ◽  
Xiaobin Jiang ◽  
...  

Mixing a polymer matrix and nanofiller to prepare a mixed matrix membrane (MMM) is an effective method for enhancing gas separation performance. In this work, a unique UiO-66-decorated halloysite nanotubes composite material (UiO-66@HNT) was successfully synthesized via a solvothermal method and dispersed into the Pebax-1657 matrix to prepare MMMs for CO2/N2 separation. A remarkable characteristic of this MMM was that the HNT lumen provided the highway for CO2 diffusion due to the unique affinity of UiO-66 for CO2. Simultaneously, the close connection of the UiO-66 layer on the external surface of HNTs created relatively continuous pathways for gas permeation. A suite of microscopy, diffraction, and thermal techniques was used to characterize the morphology and structure of UiO-66@HNT and the membranes. As expected, the embedding UiO-66@HNT composite materials significantly improved the separation performances of the membranes. Impressively, the as-obtained membrane acquired a high CO2 permeability of 119.08 Barrer and CO2/N2 selectivity of 76.26. Additionally, the presence of UiO-66@HNT conferred good long-term stability and excellent interfacial compatibility on the MMMs. The results demonstrated that the composite filler with fast transport pathways designed in this study was an effective strategy to enhance gas separation performance of MMMs, verifying its application potential in the gas purification industry.


2014 ◽  
Vol 1025-1026 ◽  
pp. 770-775 ◽  
Author(s):  
W.N.W. Salleh ◽  
N.A.I.M. Isa ◽  
Norazlianie Sazali ◽  
Ahmad Fauzi Ismail

A series of research had been conducted to alter the performance of carbon membranes by manipulating the parameters during the fabrication process. In this study, the effects of carbonization temperature on the performance of carbon membrane were investigated. Matrimid-based carbon membrane supported on ceramic tube was fabricated through the dip-coating technique. The prepared membranes were characterized by using the scanning electron microscopy (SEM) and pure gas permeation test for the study on morphological structure and gas separation performance, respectively. The carbonization process was performed at different carbonization temperatures (600, 700, and 800 oC) for the same heating rate of 1 oC/min under Ar flow. The increment of carbonization temperature produced carbon membrane with small size of pores. The carbon membrane prepared at 800 oC showed the highest CO2/CH4 and CO2/N2 selectivity of 79.65 and 74.76, respectively.


2019 ◽  
Vol 15 (1) ◽  
pp. 50-53
Author(s):  
Kok Chung Chong ◽  
Yin Yin Chan ◽  
Woei Jye Lau ◽  
Soon Onn Lai ◽  
Ahmad Fauzi Ismail ◽  
...  

Oxygen enriched air (OEA) is widely applied in various areas such as chemical and medical applications. Currently, cryogenic distillation and pressure swing adsorption are the two common technologies that being commercially used for i the production of OEA. However, these two techniques are not economically favorable due to required intensive energy and large built-up area. With the advancement of membrane technology in separation process, it garners the interest from both industrial and academic to explore the feasibility of membrane in gas separation. In this study, polysulfone (PSF) hollow fiber membranes with poly(ether block amide) (PEBAX) coating were used for the separation of O2/N2 gas. The hollow fiber membranes used in this work were fabricated by phase inversion spinning process using PSF pellet, along with N,N-dimetyhlacetamide (DMAc) and ethanol (EtOH) as solvent and co-solvent, whereas tetrahydrofuran (THF) as additive. The fabricated membrane exhibited dense structure in the inner layer whereas finger like layer at the outer surface. The formation of this structure was attributed by rapid phase inversion of the solution arose from strong solvent used. The EDX surface mapping analysis confirmed the formation of PEBAX coating on the membrane surface. Gas permeation study in this work illustrated that the pristine PSF membrane exhibited better gas separation performance relative to the PEBAX coated membrane with 20% higher in terms of permeance. The results obtained from this work suggested that the PEBAX coating enhanced the membrane surface but not certain to improve the gas separation performance. Further study on the PEBAX materials for the membrane coating is essential to polish its potential in gas separation.


Author(s):  
Salem A. Sakal

Ionic liquids (ILs) based on imidazolium and pyridinium cations and differenttypes of anions containing transition metals were investigated for extraction  of benzene from cyclohexane. The Liquid-liquid equilibrium (LLE) data are presented for six ternary systems of (Cyclohexane + Benzene + an ionic Liquid) at 298.15 K and atmospheric pressure. The ILs used in these systems are [Bmim][FeCl4], [Bmim][AlCl4], [Bmim][CuCl2], [BuPy][FeCl4]), [BuPy][AlCl4], and [C6Py][FeCl4] were all prepared in the lab. The influence of cation and anion structure of ILs on the separation selectivity and capacity for aliphatic/aromatic mixtures was analyzed. The results indicate that most ILs investigated shows both higher extractive selectivity and capacity for the aromatic components for the systems studied herein, suggesting they can be used as promising extracts for the separation of aliphatic/aromatic mixtures. The LLE data were well correlated by the non-random two-liquid (NRTL) model of non-electrolyte solutions with overall ARD deviation being about 0.0001 interm of the mole fraction based activity.


RSC Advances ◽  
2017 ◽  
Vol 7 (11) ◽  
pp. 6422-6431 ◽  
Author(s):  
Mengdie Li ◽  
Xiangping Zhang ◽  
Shaojuan Zeng ◽  
Lu bai ◽  
Hongshuai Gao ◽  
...  

A series of composite membranes with high gas transport properties enhanced by IL and ZIF-8 have been developed. The influence of ionic liquid and ZIF-8 addition on gas separation performance were systematically investigated.


Membranes ◽  
2018 ◽  
Vol 8 (4) ◽  
pp. 93 ◽  
Author(s):  
Bernardo Monteiro ◽  
Ana Nabais ◽  
Maria Casimiro ◽  
Ana Martins ◽  
Rute Francisco ◽  
...  

The efficient separation of gases has industrial, economic, and environmental importance. Here, we report the improvement in gas separation performance of a polyimide-based matrix (Matrimid®5218) filled with a Cu-based metal organic framework [MOF, Cu3(BTC)2] with two different ionic liquids (ILs) confined within the pores. The chosen ILs are commonly used in gas solubilization, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) and 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][OTf]), and the incorporation of the [EMIM][BF4]@Cu-BTC and [EMIM][OTf]@Cu-BTC composites in Matrimid®5218 proved to be an efficient strategy to improve the permeability and selectivity toward CO2/N2 and CO2/CH4 mixtures.


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