Porous Ionic Liquids Research Articles

Experimental research on the bubble dynamic characteristics during carbon capture in the novel prepared functionalized porous ionic liquids

Porous ionic liquids have received widespread attention as one of the novel CO2 absorbers to reduce CO2 produced by the combustion of fossil fuels. Based on this, the CO2 capture experiments are conducted in ionic liquids ([TEP][MIm] and [TEP][FA]), and the porous ionic liquid (ZIF-8/[TEP][MIm]). The dynamic characteristics of CO2 bubbles in different concentrations of ZIF-8/[TEP][MIm] liquid are researched. The results show that the CO2 capture capacity of the aqueous solution with a concentration of [TEP][MIm] of 20 wt% reaching 2.06 mol/mol ILs. The optimal addition amount of ZIF-8 in the porous ionic liquid using the ethylene glycol as a cosolvent is 1.0 g/100 g, and the maximum CO2 capture amount is about 2.22 mol/mol. Furthermore, the aspect ratio and cross-sectional ratio of CO2 bubbles generated by the four nozzles decrease with the increase of ZIF-8 and [TEP][MIm] concentrations, and the difference between the extreme values of CO2 equivalent diameter under experimental conditions is about 0.513 cm. In addition, the Eo number decreases with the rise of CO2 bubble, and the maximum different value is about 2.94. This work explores the dynamic characteristics of CO2 bubbles in ZIF-8/[TEP][MIm] within a bubbling tower, aiming to optimize the CO2 capture process and provide a valuable reference for advancements in the carbon capture, utilization, and storage technology.

Bifunctional pyridinium-based Brønsted acidic porous ionic liquid for deep oxidative desulfurization

Porous ionic liquids have been highlighted with special interest for their desirable catalytic activity and extraction properties. Herein, bifunctional porous ionic liquids (denoted UiO-66-BAPILs) were synthesized by dispersing UiO-66 into a pyridinium-based Brønsted acidic ionic liquid ([BSPy][CF3SO3]) for oxidative desulfurization. The permanent cavity of UiO-66 moiety in UiO-66-BAPILs was validated as well-preserved by the SO2 uptake experiments and molecular size simulations. Under the optimum reaction conditions, the sulfur removal could reach up to 99.5% with hydrogen peroxide as the oxidant. Additionally, bifunctional UiO-66-BAPILs were deemed as both extractants and catalysts during the reaction. A possible mechanism has been proposed that UiO-66-BAPILs extract the aromatic sulfur compounds via π···π interactions and C-H···π interactions and meanwhile oxidize them with peroxysulfonic acids and •OH radicals. These findings will open up new avenues to facilitate the catalytic oxidation performance by constructing bifunctional Brønsted acidic porous ionic liquids.

Incorporating porous carbon materials into ionic liquid for high efficiency extraction of polycyclic aromatic hydrocarbons

Ionic liquid is an ideal candidate in the extraction of aromatic compounds. The design and construction of ionic liquids with high extraction efficiency and selectivity towards to the specific aromatics remain crucial question. In this paper, with the aid of orthogonal array experiment, the imidazolium-based ionic liquids with long alkyl chain on the cations were determined to possess high aromatics extraction efficiency. Furthermore, the Lewis acid anion was introduced into the ionic liquid to form 1-dodecyl-3-methylimidazolium ferric chloride ([C12mim][FeCl4]) and performed 62 % and 100 % extractant efficiency of naphthalene (NAP) and anthracene (ANT), respectively. Then the porous carbon materials (P1-1000) derived from hyper-crosslinked porous polymers (HCP) which possessed high BET surface area (1186 m2/g) was dispersed in [C12mim][FeCl4] to form porous ionic liquid. The single extraction efficiency of NAP improved from 62 % to 77 %. The great single extraction efficiency was attributed to the high porosity, additional adsorption sites provided by the Lewis acid anions and the hydrophobic long alkyl chain on the cations. After three times extraction, the concentration of NAP dropped down to 0. The porous ionic liquids also showed good recycle performance. The construction of porous ionic liquids provided an efficient approach for extraction of polycyclic aromatic hydrocarbons from aliphatic hydrocarbon.

Design of dual-functional protic porous ionic liquids for boosting selective extractive desulfurization

Porous ionic liquids have demonstrated excellent performance in the field of separation, attributed to their high specific surface area and efficient mass transfer. Herein, task-specific protic porous ionic liquids (PPILs) were prepared by employing a novel one-step coupling neutralization reaction strategy for extractive desulfurization. The single-extraction efficiency of PPILs reached 75.0% for dibenzothiophene. Moreover, adding aromatic hydrocarbon interferents resulted in a slight decrease in the extraction efficiency of PPILs (from 45.2% to 37.3%, 37.9%, and 33.5%), indicating the excellent extraction selectivity of PPILs. The experimental measurements and density functional theory calculations reveal that the surface channels of porous structures can selectively capture dibenzothiophene by the stronger electrophilicity (Eint(HS surface channel/DBT) = −39.8 kcal mol−1), and the multiple extraction sites of ion pairs can effectively enrich and transport dibenzothiophene from the oil phase into PPILs through π···π, C–H···π and hydrogen bonds interactions. Furthermore, this straightforward synthetic strategy can be employed in preparing porous liquids, offering new possibilities for synthesizing PPILs with tailored functionalities.

Tailoring Type III Porous Ionic Liquids for Enhanced Liquid-Liquid Two-Phase Catalysis.

Porous Ionic Liquids (PILs) have gained attention but facing challenges in catalysis, especially in liquid-liquid two-phase reactions due to limited catalytic sites and hydrophilicity control. This work engineered a Type III PILs (PILS-M) using zeolitic imidazolate framework-8 (ZIF-8) confined phosphomolybdic acid (HPMo) as the microporous framework and N-butyl pyridine bis(trifluoromethane sulfonyl) imide ionic liquid ([Bpy][NTf2]) as the solvent. The PILS-M not only combines the advantages of traditional ionic liquids and microporous frameworks, including excellent extraction, high dispersion of catalytically active species, remarkable stability, etc., but also can make the inner surface of ZIF-8 turned to be hydrophilic that favors the contact between aqueous hydrogen peroxide oxidant and catalytically active sites for the promotion of catalytic performance in reactive extractive desulfurization (REDS) processes of fuel oils. This study demonstrates Type III PILs' potential as catalysts for sustainable chemical processes, offering insights into versatile PILs applications in diverse fields.

Porous ionic liquids for oxidative desulfurization influenced by electrostatic solvent effect

Developing a highly efficient strategy for the stabilization of the solid-liquid interface is a persistent pursuit for researchers. Herein, porous ionic liquids based on UiO-66 (Zr) porous materials were synthesized and applied to the selective desulfurization catalysis, which integrates the permanent pores of porous solids with the exceptional properties of ionic liquids. Results show that porous ionic liquids possess high activity and selectivity for dibenzothiophene. Experimental analysis and density functional theory calculations revealed that the ionic liquids moiety served as an extractant to enrich dibenzothiophene into the porous ionic liquids phase through the π···π and CH···π interactions. Additionally, the electrostatic solvent effect in the porous ionic liquids contributes to the stabilization solid-liquid interface, which was favorable for UiO-66 moiety to catalytically activate hydrogen peroxide (H2O2) to generate ·OH radicals, and subsequently oxidized dibenzothiophene to the corresponding sulfone. It is hoped that the development of porous ionic liquids could pave a new route to the stabilization of the solid-liquid interface for catalytic oxidation.

Experimental nibble for computational chemists: On the construction and CO2 capture by different zeolite imidazole ester framework‐8 and ionic

AbstractThe combination of zeolitic imidazolate framework‐8 (ZIF‐8) and ionic liquids (ILs) to create porous ionic liquids (PILs) is highly significant for efficient carbon dioxide (CO2) capture and the advancement of carbon capture, utilization, and storage (CCUS) technologies. To further investigate the CO2 capture characteristics of different PILs, two different‐sized ZIF‐8 structures and two functionalized ILs were prepared. Additionally, the enhancement factor of the reaction process was calculated using the dual‐film theory and mass transfer coefficient. The results demonstrated that the original [PMIm]Cl had low CO2 absorption capacity at ambient temperature and pressure, whereas the functionalized ILs had a maximum CO2 capture capacity of approximately .31 mol/mol, with the 20 wt% concentration of tetraethylene pentamine‐2‐methylimidazole ([TEP][MIm]) exhibiting the highest CO2 capture capacity of around 1.93 mol/mol. The synthesized PILs demonstrated a maximum CO2 capture capacity of approximately 2.22 and 2.16 mol/mol at 20 and 10 wt% ionic concentrations, respectively, with a porous ionic liquid addition of 1.0/100 g. The corresponding enhancement factors were 1.53 and 1.59, respectively. These findings have significant implications for CCUS technology.

Hierarchical Yolk-Shell Porous Ionic Liquids with Lower Viscosity for Efficient C3H6/C3H8 Adsorption and Separation.

Yolk-shell metal-organic framework (YS-MOF) liquids are candidate materials in large-size species with high-efficiency separation, owing to their hierarchical porosity, faster mass transfer, better compatibility, and higher solution processability than MOF liquids with micropores. Nevertheless, facile synthesis strategies of yolk-shell porous ionic liquids (YSPILs) with regulations of size and morphology are an ongoing challenge. Herein, we propose a general strategy to construct YSPILs based on Z67@PDA with tunable core sizes and morphologies. Benefiting from the unique hierarchical yolk-shell structure, as-prepared YSPILs exhibit promise in C3H6/C3H8 capture and separation with the increased sizes of core in yolk-shell ZIF-67@PDA. Advanced YS-MOF liquids have improved the adsorption properties and increased our ability to tailor chemical composition and pore architecture. Impressively, the adsorption capacity of C3H6 and C3H8 of YSPILs exhibits an approximately 3-fold enhancement compared with that of the neat ILs, confirming that the accessible porosities are retained. Effective C3H6/C3H8 separation performance of YSPILs over PILs based on ZIF-67, revealing the hierarchical porosity of YS-Z67@PDA liquids, benefits larger-size gas separation. Therefore, we believe that this work can not only help us to rationally design novel hierarchically porous ionic liquids but also promote candidate applications in large-size species separation, catalysis, and nanoreactors.

Rational Design of Porous Ionic Liquids for Coupling Natural Gas Purification with Waste Gas Conversion

AbstractRemoval of trace impurities for natural gas purification coupled with waste gas conversion is highly desired in industry. We here report a type of porous ionic liquids (PILs) that can realize the continuous flow separation of CH4/CO2/H2S and the conversion of the captured H2S to useful products. The PILs are synthesized through a step‐by‐step surface modification of ionic liquids (ILs) onto UiO‐66‐OH nanocrystals. The introduction of free tertiary amine groups on the nanocrystal surface endows these PILs with an exceptional ability to enrich H2S from CO2 and CH4 with impressive selectivity, while the permanent pores of UiO‐66‐OH act as containers to store an exceptionally higher amount of the selectively captured H2S than the corresponding nonporous ILs. Simultaneously, the tertiary amines as dual functional moieties offer effective catalytic sites for the conversion of the H2S stored in PILs into 3‐mercaptoisobutyric acid, a key intermediate required for the synthesis of Captopril (an antihypertensive drug). Molecular dynamics, density functional theory calculations and Grand Canonical Monte Carlo simulations help understand both the mechanisms of separation and catalysis performance, confirming that the tertiary amines as well as the permanent pores in UiO‐66‐OH play vital roles in the whole procedure.

Rational Design of Porous Ionic Liquids for Coupling Natural Gas Purification with Waste Gas Conversion.

Removal of trace impurities for natural gas purification coupled with waste gas conversion is highly desired in industry. We here report a type of porous ionic liquids (PILs) that can realize the continuous flow separation of CH4 /CO2 /H2 S and the conversion of the captured H2 S to useful products. The PILs are synthesized through a step-by-step surface modification of ionic liquids (ILs) onto UiO-66-OH nanocrystals. The introduction of free tertiary amine groups on the nanocrystal surface endows these PILs with an exceptional ability to enrich H2 S from CO2 and CH4 with impressive selectivity, while the permanent pores of UiO-66-OH act as containers to store an exceptionally higher amount of the selectively captured H2 S than the corresponding nonporous ILs. Simultaneously, the tertiary amines as dual functional moieties offer effective catalytic sites for the conversion of the H2 S stored in PILs into 3-mercaptoisobutyric acid, a key intermediate required for the synthesis of Captopril (an antihypertensive drug). Molecular dynamics, density functional theory calculations and Grand Canonical Monte Carlo simulations help understand both the mechanisms of separation and catalysis performance, confirming that the tertiary amines as well as the permanent pores in UiO-66-OH play vital roles in the whole procedure.

Porous Ionic Liquids Go Green.

This Perspective points toward pathways to prepare porous ionic liquids using easily accessible materials, aiming for reduced environmental impact. We demonstrate that suspensions of porous solids are stable in eutectic mixtures, underscoring their potential for the preparation of porous ionic liquids. Porous ionic liquids retain the wide electrochemical window observed in their precursor pure ionic liquids, rendering them well-suited for green electrochemical reactions, particularly those involving gases whose solubility is enhanced in the porous suspensions. Moreover, their capacity as gas-rich media points to sustainable biomedical and pharmaceutical applications, provided nontoxic, biocompatible ionic liquids and porous solids are utilized.

Constructing protic porous ionic liquids via one-step coupling neutralization reaction for extraction-adsorption coupled desulfurization

Porous ionic liquids (PILs) offer a distinctive combination of liquid-like fluidity and solid porosity, making them well-suited for various applications including separation, catalysis, and energy storage. Nevertheless, the design limitations and complex synthesis processes have hindered the development of PILs. Here, the one-step coupling neutralization reaction (OCNR) method has been first proposed for the controllable synthesis of functionalized protic porous ionic liquids (PPILs). Specifically, three types of PPILs have been synthesized based on tuning the position of the corona amino functional groups. The results indicate the crucial role of protic ion pairs in the formation of pure liquid PPILs with low viscosity. The extraction efficiency has obviously increased after introducing the porous materials from 38.5% to 51.9%. The results showed PPILs play good extraction-adsorption coupled desulfurization (EADS) performance. The density functional theory (DFT) results show that both the protic ion pairs and the porous structure have significant roles in EADS, with the former offering CH···π interactions, while the latter provides hydrogen bonding (CH···O) interactions. Ultimately, the strategy simplifies the synthesis process, providing a new idea for the directional design of low-viscosity PILs with specific functions.

UiO-66(Zr)-based porous ionic liquids for highly efficient extraction coupled catalytic oxidative desulfurization

Porous ionic liquids are a novel category media that possesses the catalytic activity of porous solids and the extraction property of ionic liquids. Herein, a new type of porous ionic liquids (denoted as UiO-66-T3PILs) was fabricated by employing UiO-66(Zr) as the pore generator and the ionic liquid ([P6,6,6,14][NTF2]) as the size-excluded solvent for extraction coupled catalytic oxidative desulfurization (ECODS) using hydrogen peroxide (H2O2, 30 wt%) as an oxidant. Furthermore, several significant reaction parameters such as UiO-66 loading in porous ionic liquids, reaction temperatures, molar ratio of H2O2/DBT and sulfide species as well as recyclability were investigated in detail. As UiO-66-T3PILs exhibited higher efficiency (95.3%) than the summarized efficiency of UiO-66 and [P6,6,6,14][NTF2], there did exist a synergistic effect between the UiO-66(Zr) moiety and the ionic liquid moiety in UiO-66-T3PILs. With the assistance of density functional theory calculations, a possible mechanism was proposed that aromatic sulfur compounds in the oil phase were first extracted into ionic liquids moiety phase via C-H···π interactions and then rapidly oxidized by OH radicals in the presence of the UiO-66 moiety. This work will pave the way for the rational design of novel porous ionic liquids towards catalysis.

Solvation Environments in Porous Ionic Liquids Determine Selectivity in CO2 Conversion to Cyclic Carbonates.

Porous ionic liquids, which are suspensions of nanoporous particles in ionic liquids that maintain permanent porosity, are effective and selective media for the conversion of styrene oxide into styrene carbonate, absorbing CO2 [Zhou et al. Chem. Commun. 2021, 57, 7922-7925]. Here we elucidate the mechanism of selectivity using polarizable molecular dynamics simulations, which provide a detailed view on the structure of the porous ionic liquid and on the local solvation environments of the reacting species. The porous ionic liquids studied are composed of tetradecyltrihexylphosphonium chloride, or [P66614]Cl, and the ZIF-8 zinc-methylimidazolate metal-organic framework (MOF). The CL&Pol polarizable force field was extended to represent epoxide and cyclic carbonate functional groups, allowing the ionic liquid, the reactants, and the MOF to be all represented by fully flexible, polarizable force fields, providing a detailed description of interactions. The presence of reactant and product molecules leads to changes in the structure of the ionic liquid, revealed by domain analysis. The structure of local solvation environments, namely, the arrangement of charged moieties and CO2 around the epoxide ring of the reactant molecules, clearly indicate ring-opening the reaction mechanism. The MOF acts as a reservoir of CO2 through its free volume. The solute molecules are found in the accessible outer cavities of the MOF, which promotes reaction of the epoxide with CO2 excluding other epoxide molecules, thereby preventing the formation of oligomers, which explains the selectivity toward conversion to cyclic carbonates.

Highly efficient extractive desulfurization by specific functionalized porous ionic liquids via C-H···π interactions

Porous ionic liquids (PILs) are an emerging class of materials that possess the porosity of solids and the fluidity of liquids, which have shown great potential in separation. Herein, a novel kind of silica-based porous ionic liquids (OS-PIL) functionalized with quaternary ammonium salt was successfully synthesized to remove the dibenzothiophene (DBT) in the model fuel. The OS-PIL exhibit high extraction activity and its Nernst partition coefficient could reach up to 4.22. The experimental results indicated that a synergistic effect between porous materials and ionic liquids as well as the multiple sites in quaternary ammonium salt greatly contributed to the high extractive desulfurization efficiency. Moreover, density functional theory (DFT) calculations and spectroscopic investigations were employed to gain in-depth insights into the extraction mechanism. The results demonstrated that the porous structure and ion pair of OS-PIL exhibit stronger interaction for DBT, in which the C-H···π is dominant. These kinds of PILs with highly specific surface areas and multiple active sites will have good application prospects in the field of extractive desulfurization.

Microscopic Study on the Performance Optimization of Porous Ionic Liquids for CO2 Capture by Selection of Crown Ether Solvents

Microscopic Study on the Performance Optimization of Porous Ionic Liquids for CO₂ Capture by Selection of Crown Ether Solvents

Flexible multisensory sensor based on hierarchically porous ionic liquids/thermoplastic polyurethane composites

With the rapid development of wearable electronics and electronic skins, the demand for portable and flexible sensors that can perceive surrounding information, including mechanical forces, temperature, and humidity, is dramatically increasing. Herein, we develop a lightweight and flexible multisensory sensor based on the hierarchically porous ionic liquids (ILs)/thermoplastic polyurethane (TPU) composite by the combination of vapor-induced phase separation technique and ultrasound-assisted anchoring technique. The as-prepared porous TPU@ILs sensor possesses both the strain- and temperature- sensing capabilities. As a strain sensor, it exhibits excellent sensing performance in various aspects, such as ultra-low detection limit (0.5%), ultra-wide sensing range (0.5–600%), fast response/recovery time (100 ms/80 ms), and outstanding durability, attributed to the hierarchically porous microstructure of TPU@ILs composites. Due to the rigid conductivity-temperature dependence of ILs, the designed porous TPU@ILs sensor also possesses outstanding temperature sensing capability, which has both the high temperature resolution (0.05 °C) and ultrawide temperature sensing range (−30–80 °C). This work provides an effective but simple strategy to fabricate high-performance multisensory sensors, which have great potentials in electronic skins and wearable electronics.

Pore size-excluded low viscous porous liquids for CO2 sorption at room temperature and thermodynamic modeling study

Herein, we report porous ionic liquids (type-III) designed to utilize microporous ZIF-8 moieties with functional ionic liquids such as 8-(2-methoxyethyl)-1,8-Diazabicyclo[5.4.0]undec-7-en-8-ium, Bis(trifluoromethane)sulfonamide ([MEDBU][TFSI] and Trioctylammonium 4-para-tert-butylbenzoiate [TOAH][PTBBA]). The prepared materials were thoroughly characterized by means of XRD, FT-IR, SEM, TEM, BET, TGA, DSC and viscometry techniques. The idea of combining the intrinsic properties of ionic liquids with microporous architecture to prepare porous ionic liquids yields promising fluidic materials that have received attention in industrial applications such as gas sorption and separation etc. The prepared porous ionic liquids possess unique physico-chemical properties such as low viscosity, high thermal stability, low vapor pressure, reusability and their fluidic nature renders the materials suitable for CO2 capture. Herein introduced porous ionic liquids (ILs) showed enhanced CO2 uptake (0.92 mmol/g in [TOAH][PTBBA]-Z100 and 1.16 mmol/g in [MEDBU][TFSI]-Z200), or in other words, 15–47% higher sorption capacity compared to neat ionic liquids. This concept overcomes the drawbacks of highly viscous ILs and their limited CO2 sorption capacity. Thermodynamic modeling further demonstrated that the enthalpy of sorption is only −9.99 kJ mol−1, indicating that significantly less energy is required for regeneration. This is promising for the potential use of these fluidic materials in continuous separation processes on an industrial scale, as a better alternative to the existing hazardous amine scrubbing.

Phosphomolybdic acid encapsulated in ZIF-8-based porous ionic liquids for reactive extraction desulfurization of fuels

Phosphomolybdic acid was encapsulated within a ZIF-8-based porous ionic liquid (HPMo@ZIF-8-PIL) for ultradeep reactive extraction desulfurization.

Porous ionic liquids: beyond the bounds of free volume in a fluid phase

After reviewing the synthesis, characterization and applications of 150+ porous suspensions, we conclude that type III porous liquids are either suspensions of MOFs in ionic liquids and liquid polymers or of decorated MOFs in molecular solvents.