Decreasing the Viscosity in CO2 Capture by Amino-Functionalized Ionic Liquids through the Formation of Intramolecular Hydrogen Bond

Intermolecular Proton Transfer Enabled Reactive CO2 Capture by the Malononitrile Anion

Task-specific ionic liquids (ILs) employing carbanions represent a new class of ILs for carbon capture. The deprotonated malononitrile carbanion, [CH(CN)2]-, has shown close to equimolar capacity for reactive CO2 capture. Although the formation of the [C(CN)2COOH]- carboxylic acid was found to be the final product, how the hydrogen atom on the [CH(CN)2]- carbanion transfers to the carboxylate group as a proton has not been fully understood. In this work, we employ density functional theory calculations with an implicit solvation model to investigate the proton transfer mechanisms in forming carboxylic acid from the reaction of the [CH(CN)2]- carbanion with CO2. We find that the intramolecular proton-transfer pathway in [CH(CN)2COO]- to form [C(CN)2COOH]- is unlikely due to the high energy barrier of 152 kJ/mol. Instead, the intermolecular proton transfer pathway between two [CH(CN)2COO]- anions is more feasible to form two molecules of [C(CN)2COOH]-, with a significantly lower activation energy of 50 kJ/mol. Moreover, the [C(CN)2COOH]- dimer is further stabilized by the intermolecular hydrogen bonds of the two -COOH groups in the Z-configuration of the π-conjugated planar geometry. This insight of reactive CO2 capture enabled by intermolecular proton transfer will be useful in designing novel carbanions and ILs for carbon capture and conversion.

Treatment and Resource Utilization of Gaseous Pollutants in Functionalized Ionic Liquids

With the rapid development of science, technology, and the economy of human society, the emission problem of gas pollutants is becoming more and more serious, which brings great pressure to the global ecological environment. At the same time, the natural resources that can be exploited and utilized on Earth are also showing a trend of exhaustion. As an innovative and environmentally friendly material, functionalized ionic liquids (FILs) have shown great application potential in the capture, separation, and resource utilization of gaseous pollutants. In this paper, the synthesis and characterization methods of FILs are introduced, and the application of FILs in the treatment and recycling of gaseous pollutants is discussed. The future development of FILs in this field is also anticipated, which will provide new ideas and methods for the treatment and recycling of gaseous pollutants and promote the process of environmental protection and sustainable development.

Surpassing the Performance of Phenolate-derived Ionic Liquids in CO2 Chemisorption by Harnessing the Robust Nature of Pyrazolonates

Superbase-derived ionic liquids (SILs) are promising sorbents to tackle the carbon challenge featured by tunable interaction strength with CO2 via structural engineering, particularly the oxygenate-derived counterparts (e. g., phenolate). However, for the widely deployed phenolate-derived SILs, unsolved stability issues severely limited their applications leading to unfavorable and diminished CO2 chemisorption performance caused by ylide formation-involved side reactions and the phenolate-quinone transformation via auto-oxidation. In this work, robust pyrazolonate-derived SILs possessing anti-oxidation nature were developed by introducing aza-fused rings in the oxygenate-derived anions, which delivered promising and tunable CO2 uptake capacity surpassing the phenolate-based SIL via a carbonate formation pathway (O-C bond formation), as illustrated by detailed spectroscopy studies. Further theoretical calculations and experimental comparisons demonstrated the more favorable reaction enthalpy and improved anti-oxidation properties of the pyrazolonate-derived SILs compared with phenolate anions. The achievements being made in this work provides a promising approach to achieve efficient carbon capture by combining the benefits of strong interaction strength of oxygenate species with CO2 and the stability improvement enabled by aza-fused rings introduction.

Experimental study on CO2 capture by MEA/n-butanol/H2O phase change absorbent

Monoethanolamines (MEAs) are widely used for CO2 capture, but their regeneration energy consumption is very high. CO2 Phase change absorbents (CPCAs) can be converted into CO2-rich and CO2-lean phases after absorbing CO2, and the regeneration energy consumption can be reduced because only the CO2-rich phase is thermally desorbed. In this paper, a novel CPCA with the composition "MEA/n-butanol/H2O (MNBH)" is proposed. Compared with the reported MEA phase change absorbent, the MNBH absorbent has higher CO2 absorption capacity, smaller absorbent viscosity and CO2-rich phase volume. The MNBH absorbent has the highest CO2 absorption capacity of 2.5227 mol CO2 per mol amine at a mass ratio of 3 : 4 : 3. The CO2 desorption efficiency reaches 89.96% at 120 °C, and the CO2 regeneration energy consumption is 2.6 GJ tCO2-1, which is about 35% lower than that of the 30 wt% MEA absorbent. When the mass ratio of MNBH absorbent was 3 : 6 : 1, the CO2 recycling capacity was 4.1918 mol CO2 L-1, which is 76% higher than that of the conventional 30 wt% MEA absorbent. The phase change absorbent developed in this paper can reduce the desorbent volume by about 50% and has good absorption performance for CO2 in flue gas.

Ionic Liquids Hybridization for Carbon Dioxide Capture: A Review

CO2 absorption has been driven by the need for efficient and environmentally sustainable CO2 capture technologies. The development in the synthesis of ionic liquids (ILs) has attracted immense attention due to the possibility of obtaining compounds with designated properties. This allows ILs to be used in various applications including, but not limited to, biomass pretreatment, catalysis, additive in lubricants and dye-sensitive solar cell (DSSC). The utilization of ILs to capture carbon dioxide (CO2) is one of the most well-known processes in an effort to improve the quality of natural gas and to reduce the green gases emission. One of the key advantages of ILs relies on their low vapor pressure and high thermal stability properties. Unlike any other traditional solvents, ILs exhibit high solubility and selectivity towards CO2. Frequently studied ILs for CO2 absorption include imidazolium-based ILs such as [HMIM][Tf2N] and [BMIM][OAc], as well as ILs containing amine groups such as [Cho][Gly] and [C1ImPA][Gly]. Though ILs are being considered as alternative solvents for CO2 capture, their full potential is limited by their main drawback, namely, high viscosity. Therefore, the hybridization of ILs has been introduced as a means of optimizing the performance of ILs, given their promising potential in capturing CO2. The resulting hybrid materials are expected to exhibit various ranges of chemical and physical characteristics. This review presents the works on the hybridization of ILs with numerous materials including activated carbon (AC), cellulose, metal-organic framework (MOF) and commercial amines. The primary focus of this review is to present the latest innovative solutions aimed at tackling the challenges associated with IL viscosity and to explore the influences of ILs hybridization toward CO2 capture. In addition, the development and performance of ILs for CO2 capture were explored and discussed. Lastly, the challenges in ILs hybridization were also being addressed.

Integrated CO2 capture and electrochemical upgradation: the underpinning mechanism and techno-chemical analysis

Coupling post-combustion CO2 capture with electrochemical utilization (CCU) is a quantum leap in renewable energy science since it eliminates the cost and energy involved in the transport and storage of CO2. However, the major challenges involved in industrial scale implementation are selecting an appropriate solvent/electrolyte for CO2 capture, modeling an appropriate infrastructure by coupling an electrolyser with a CO2 point source and a separator to isolate CO2 reduction reaction (CO2RR) products, and finally selection of an appropriate electrocatalyst. In this review, we highlight the major difficulties with detailed mechanistic interpretation in each step, to find out the underpinning mechanism involved in the integration of electrochemical CCU to achieve higher-value products. In the past decades, most of the studies dealt with individual parts of the integration process, i.e., either selecting a solvent for CO2 capture, designing an electrocatalyst, or choosing an ideal electrolyte. In this context, it is important to note that solvents such as monoethanolamine, bicarbonate, and ionic liquids are often used as electrolytes in CO2 capture media. Therefore, it is essential to fabricate a cost-effective electrolyser that should function as a reversible binder with CO2 and an electron pool capable of recovering the solvent to electrolyte reversibly. For example, reversible ionic liquids, which are non-ionic in their normal forms, but produce ionic forms after CO2 capture, can be further reverted back to their original non-ionic forms after CO2 release with almost 100% efficiency through the chemical or thermal modulations. This review also sheds light on a focused techno-economic evolution for converting the electrochemically integrated CCU process from a pilot-scale project to industrial-scale implementation. In brief, this review article will summarize a state-of-the-art argumentation of challenges and outcomes over the different segments involved in electrochemically integrated CCU to stimulate urgent progress in the field.

Reaction Mechanism of CO2 with Choline-Amino Acid Ionic Liquids: A Computational Study

Carbon capture and sequestration are the major applied techniques for mitigating CO2 emission. The marked affinity of carbon dioxide to react with amino groups is well known, and the amine scrubbing process is the most widespread technology. Among various compounds and solutions containing amine groups, in biodegradability and biocompatibility perspectives, amino acid ionic liquids (AAILs) are a very promising class of materials having good CO2 absorption capacity. The reaction of amines with CO2 follows a multi-step mechanism where the initial pathway is the formation of the C-N bond between the NH2 group and CO2. The added product has a zwitterionic character and can rearrange to give a carbamic derivative. These steps of the mechanism have been investigated in the present study by quantum mechanical methods by considering three ILs where amino acid anions are coupled with choline cations. Glycinate, L-phenylalanilate and L-prolinate anions have been compared with the aim of examining if different local structural properties of the amine group can affect some fundamental steps of the CO2 absorption mechanism. All reaction pathways have been studied by DFT methods considering, first, isolated anions in a vacuum as well as in a liquid continuum environment. Subsequently, the role of specific interactions of the anion with a choline cation has been investigated, analyzing the mechanism of the amine-CO2 reaction, including different coupling anion-cation structures. The overall reaction is exothermic for the three anions in all models adopted; however, the presence of the solvent, described by a continuum medium as well as by models, including specific cation- -anion interactions, modifies the values of the reaction energies of each step. In particular, both reaction steps, the addition of CO2 to form the zwitterionic complex and its subsequent rearrangement, are affected by the presence of the solvent. The reaction enthalpies for the three systems are indeed found comparable in the models, including solvent effects.

A QCT View of the Interplay between Hydrogen Bonds and Aromaticity in Small CHON Derivatives

The somewhat elusive concept of aromaticity plays an undeniable role in the chemical narrative, often being considered the principal cause of the unusual properties and stability exhibited by certain π skeletons. More recently, the concept of aromaticity has also been utilised to explain the modulation of the strength of non-covalent interactions (NCIs), such as hydrogen bonding (HB), paving the way towards the in silico prediction and design of tailor-made interacting systems. In this work, we try to shed light on this area by exploiting real space techniques, such as the Quantum Theory of Atoms in Molecules (QTAIM), the Interacting Quantum Atoms (IQA) approaches along with the electron delocalisation indicators Aromatic Fluctuation (FLU) and Multicenter (MCI) indices. The QTAIM and IQA methods have been proven capable of providing an unbiased and rigorous picture of NCIs in a wide variety of scenarios, whereas the FLU and MCI descriptors have been successfully exploited in the study of diverse aromatic and antiaromatic systems. We used a collection of simple archetypal examples of aromatic, non-aromatic and antiaromatic moieties within organic molecules to examine the changes in π delocalisation and aromaticity induced by the Aromaticity and Antiaromaticity Modulated Hydrogen Bonds (AMHB). We observed fundamental differences in the behaviour of systems containing the HB acceptor within and outside the ring, e.g., a destabilisation of the rings in the former as opposed to a stabilisation of the latter upon the formation of the corresponding molecular clusters. The results of this work provide a physically sound basis to rationalise the strengthening and weakening of AMHBs with respect to suitable non-cyclic non-aromatic references. We also found significant differences in the chemical bonding scenarios of aromatic and antiaromatic systems in the formation of AMHB. Altogether, our investigation provide novel, valuable insights about the complex mutual influence between hydrogen bonds and π systems.

Ammonium-, phosphonium- and sulfonium-based 2-cyanopyrrolidine ionic liquids for carbon dioxide fixation

The development of carbon dioxide (CO₂) scavengers is an acute problem nowadays because of the global warming problem. Many groups around the globe intensively develop new greenhouse gas scavengers. Room-temperature ionic liquids (RTILs) are seen as a proper starting point to synthesize more environmentally friendly and high-performance sorbents. Aprotic heterocyclic anions (AHA) represent excellent agents for carbon capture and storage technologies. In the present work, we investigate RTILs in which both the weakly coordinating cation and AHA bind CO₂. The ammonium-, phosphonium-, and sulfonium-based 2-cyanopyrrolidines were investigated using the state-of-the-art method to describe the thermochemistry of the CO₂ fixation reactions. The infrared spectra and electronic and structural properties were simulated at the hybrid density functional level of theory to characterize the reactants and products of the chemisorption reactions. We conclude that the proposed CO₂ capturing mechanism is thermodynamically allowed and discuss the difference between different families of RTILs. Quite unusually, the intramolecular electrostatic attraction plays an essential role in stabilizing the zwitterionic products of the CO₂ chemisorption. The difference in chemisorption performance between the families of RTILs is linked to sterical hindrances and nucleophilicities of the α- and β-carbon atoms of the aprotic cations. Our results rationalize previous experimental CO₂ sorption measurements (Brennecke et al., 2021).

New-Generation Carbon-Capture Ionic Liquids Regulated by Metal-Ion Coordination

Development of efficient carbon capture-and-release technologies with minimal energy input is a long-term challenge in mitigating CO₂ emissions, especially via CO₂ chemisorption driven by engineered chemical bond construction. Herein, taking advantage of the structural diversity of ionic liquids (ILs) in tuning their physical and chemical properties, precise reaction energy regulation of CO₂ chemisorption was demonstrated deploying metal-ion-amino-based ionic liquids (MAILs) as absorbents. The coordination ability of different metal sites (Cu, Zn, Co, Ni, and Mg) to amines was harnessed to achieve fine-tuning on stability constants of the metal ion-amine complexes, acting as the corresponding cations in the construction of diverse ILs coupled with CO₂ -philic anions. The as-afforded MAILs exhibited efficient and controllable CO₂ release behavior with great reduction in energy input and minimal sacrifice on CO₂ uptake capacity. This coordination-regulated approach offers new prospects for the development of ILs-based systems and beyond towards energy-efficient carbon capture technologies.

Experimental studies on CO2 absorption and solvent recovery in aqueous blends of monoethanolamine and tetrabutylammonium hydroxide

Solvent-based post-combustion CO₂ capture process is recently carried out using chemical absorption with aqueous blends of Monoethanolamine (MEA) and Ionic Liquids (IL) as promising solvents. In the present work, the blends of MEA and TetraButylAmmonium Hydroxide [TBA][OH] have been used for CO₂ absorption and desorption process. The solubility of CO₂ is investigated with aqueous mixtures for various carbon loading time by varying compositions of MEA and [TBA][OH] as 30 wt%, 28 wt%, 25 wt%, 20 wt% and 0 wt%, 2 wt%, 5 wt%, 10 wt% respectively. It increases with increasing IL concentration for all the aqueous mixtures. The solvent regeneration was also studied at different temperatures in order to recover and reuse the solvent for cyclic absorption. The slight decrease in CO₂ solubility was noted for 20 wt% MEA +10 wt% [TBA][OH] mixture. However, this mixture exhibits higher absorption/desorption rate and regeneration efficiency than other mixtures. The regeneration energy of this mixture was also calculated as 28.6 kJ/mol of CO₂, which is 32% less than that of baseline 30 wt% MEA. Furthermore, the physicochemical properties such as density, viscosity and surface tension for all the solvent blends were studied experimentally.

CO2 Capture in Biocompatible Amino Acid Ionic Liquids: Exploring the Reaction Mechanisms for Bimolecular Absorption Processes

CO2 capture at the production site represents one of the accessible ways to reduce its emission in the atmosphere. In this context, CO2 chemisorption is particularly advantageous and is often based on exploiting a liquid containing amino groups that can trap CO2 due to their propensity to react with it to yield carbamic derivatives. A well-known class of ionic liquids based on amino acid anions might represent an ideal medium for CO2 capture because, at difference with present implementations, they are known to be fully biocompatible. One of the problems is however the relatively low molar ratio of CO2 absorption. Increasing this ratio turns out to be possible by choosing appropriate anions. We present here a set of accurate computations to elucidate the possible reaction paths that allow the anion to absorb two CO2 molecules, thus effectively doubling the overall intake. An extensive exploration of some reaction mechanisms suggests that some of them might be quite efficient even under mild conditions.

Modelling biocompatible ionic liquids based on organic acids and amino acids: challenges for computational models and future perspectives

In this short review I shall highlight the basic principle and the difficulties that arise in attempting the computational modeling of seemingly simple systems which hide an unexpected complexity. Biocompatible ionic liquids which are based on the coupling of organic or amino acid anions with metabolic cations such as cholinium are the target of this review. These substances have been the subject of intense research activities in the last few years and have attracted the attention of computational chemists. I shall show that the computational description of these substances is far from trivial and requires the use of sophisticated techniques in order to account for a surprisingly rich chemistry that is due to several phenomena such as polarization, charge transfer, proton transfer equilibria and tautomerization reactions.

An electrochemical setup designed for carbon dioxide solubility measurements in ionic liquids

An electrochemical setup was designed and built to evaluate carbon dioxide solubility in ionic liquids. The setup can simultaneously measure amounts of CO₂ in the gas and in the ionic liquid phase, making it very useful for in situ electrochemical measurements. The home-built glass cell is able to withstand high vacuum allowing the ionic liquid samples to be properly evacuated before characterization and kept free of contaminants during experiments. A pressure gauge attached to the setup enables continuous monitoring of gas added to the system. This kind of configuration can measure gas solubility in ionic liquids expressed as Henry's constants determined from generated plots of dissolved gas concentration in the ionic liquid vs headspace gas pressure. It also serves as a more economical alternative to other gas solubility measurement techniques, as it is predominantly made of glass, and requires minimal sample amounts. The setup can be useful in determining the solubility of various gases in ionic liquids.

Cholinium amino acid-based ionic liquids

Boosted by the simplicity of their synthesis and low toxicity, cholinium and amino acid-based ionic liquids have attracted the attention of researchers in many different fields ranging from computational chemistry to electrochemistry and medicine. Among the uncountable IL variations, these substances occupy a space on their own due to their exceptional biocompatibility that stems from being entirely made by metabolic molecular components. These substances have undergone a rather intensive research activity because of the possibility of using them as greener replacements for traditional ionic liquids. We present here a short review in the attempt to provide a compendium of the state-of-the-art scientific research about this special class of ionic liquids based on the combination of amino acid anions and cholinium cations.

Molecular simulation on the stability and adsorption properties of choline-based ionic liquids/IRMOF-1 hybrid composite for selective H2S/CO2 capture

The compatibility and performance of an Isoreticular Metal-Organic Frameworks (IRMOF-1) impregnated with choline-based ionic liquids (ILs) for selective adsorption of H₂S/CO₂, were studied by molecular dynamics (MD) simulation. Cholinium alanate ([Chl][Ala]) was nominated as the suitable IL for impregnation into IRMOF-1, consistent with the low RMSD values (0.546 nm, 0.670 nm, 0.776 nm) at three IL/IRMOF-1 w/w ratios (W_IL/IRMOF-1 = 0.4, 0.8, and 1.2). The [Chl]⁺ and [Ala]^- ion pair was located preferentially around the carboxylate group within the IRMOF-1 framework, with the latter interacting strongly with the host than the [Chl]⁺. Results of radius of gyration (Rg) and root mean square displacement (RMSD) revealed that a ratio of 0.4 w/w of IL/IRMOF-1 (Rg = 1.405 nm; RMSD = 0.546 nm) gave the best conformation to afford an exceptionally stable IL/IRMOF-1 composite. It was discovered that the IL/IRMOF-1 composite was more effective in capturing H₂S and CO₂ compared to pristine IRMOF-1. The gases adsorbed in higher quantities in the IL/IRMOF-1 composite phase compared to the bulk phase, with a preferential adsorption for H₂S, as shown by the uppermost values of adsorption ( [Formula: see text] = 17.954 mol L^-1 bar^-1) and an adsorption selectivity ( [Formula: see text] = 43.159) at 35 IL loading.

Ultrafast vibrational dynamics of a trigonal planar anionic probe in ionic liquids (ILs): A two-dimensional infrared (2DIR) spectroscopic investigation

A major impediment limiting the widespread application of ionic liquids (ILs) is their high shear viscosity. Incorporation of a tricyanomethanide (TCM^-) anion in ILs leads to low shear viscosity and improvement of several characteristics suitable for large scale applications. However, properties including interactions of TCM^- with the local environment and dynamics of TCM^- have not been thoroughly investigated. Herein, we have studied the ultrafast dynamics of TCM^- in several imidazolium ILs using linear IR and two-dimensional infrared spectroscopy techniques. The spectral diffusion dynamics of the CN stretching modes of TCM^- in all ILs exhibit a nonexponential behavior with a short time component of ∼2 ps and a long time component spanning ∼9 ps to 14 ps. The TCM^- vibrational probe reports a significantly faster relaxation of ILs compared to those observed previously using linear vibrational probes, such as thiocyanate and selenocyanate. Our results indicate a rapid relaxation of the local ion-cage structure embedding the vibrational probe in the ILs. The faster relaxation suggests that the lifetime of the local ion-cage structure decreases in the presence of TCM^- in the ILs. Linear IR spectroscopic results show that the hydrogen-bonding interaction between TCM^- and imidazolium cations in ILs is much weaker. Shorter ion-cage lifetimes together with weaker hydrogen-bonding interactions account for the low shear viscosity of TCM^- based ILs compared to commonly used ILs. In addition, this study demonstrates that TCM^- can be used as a potential vibrational reporter to study the structure and dynamics of ILs and other molecular systems.

Development of High-Capacity and Water-Lean CO2 Absorbents by a Concise Molecular Design Strategy through Viscosity Control

The exponentially increasing viscosity of water-lean CO₂ absorbents during carbon capture processes is a critical problem for practical application, owing to its strong correlation with systems' mass transfer properties, as well as convenience of transportation. In this work, a concise strategy based on structure-viscosity relationships is proposed and applied to construct a series of functionalized ethylenediamines as single-component absorbents for post-combustion CO₂ capture. These nonaqueous absorbents have outstanding viscosities (50-200 cP, 25 °C) at their maximal CO₂ capacities (up to 22 wt % or 4.92 mol kg^-1 , 1 bar), and are readily regenerated at low temperatures (50-80 °C) under ambient pressure. Additional capture of CO₂ through physisorption could also be achieved by operating at high pressures. The CO₂ capture and release process is systematically investigated by means of ¹³ C NMR spectroscopy, differential scanning calorimetry (DSC), in situ FTIR analysis, and density functional theory (DFT) calculations, which could provide sufficient spectroscopic details to reveal the ease of reversibility and enable rational interpretation of the absorption mechanism.

Tuning the Capture of CO2 through Entropic Effect Induced by Reversible Trans-Cis Isomerization of Light-Responsive Ionic Liquids

Despite a great deal of gas capture strategies based on ionic liquids, reversible tuning of gas absorption by pure ionic liquids using light irradiation has never been reported. Herein, we demonstrate a novel strategy for tuning the capture of CO₂ by light-responsive ionic liquids through reversible trans-cis isomerization. These light-responsive ionic liquids were constructed by tailoring the azobenzene group to the cationic moiety, which exhibited different CO₂ absorption ability before and after ultraviolet (UV) irradiation. Through a combination of absorption experiments, NMR spectroscopy, differential scanning calorimetry analysis, viscosity measurement, and quantum chemical calculations, the results indicated that the significant difference in CO₂ absorption capacity originated from the entropic effect, which was induced by the change in the aggregation state during trans-cis isomerization. This reversible isomerization of ionic liquids upon alternating irradiation of UV light and blue light shows the potential to control the capture and release of CO₂ in an energy-saving way.

Enhanced CO2 capture by reducing cation-anion interactions in hydroxyl-pyridine anion-based ionic liquids

In this work, an efficient strategy for improving CO2 capture based on anion-functionalized ionic liquids (ILs) by reducing cation-anion interactions in ILs was reported. The influence of the cationic species on CO2 absorption was investigated using 2-hydroxyl pyridium anions ([2-Op]) as a probe. CO2 capture experiments indicated that the CO2 absorption capacity in [2-Op] anion-based ILs varied from 0.94 to 1.69 mol CO2 per mol IL at 30 °C and 1 atm. Spectroscopic analysis and quantum chemical calculations suggested that the increase of the CO2 absorption capacity may be ascribed to the reduction of the strength of cation-anion interactions in ILs, and stronger cation-anion interactions would make one CO2 site in the [2-Op] anion inactive. Furthermore, the effect of the cation unit on the anion was evidenced by FT-IR spectra, implying that strong interactions between ions may lead to the decrease of the IR absorption wavenumber of hydroxy pyridium and work against CO2 capture. Following this strategy, it was finally found that [Ph-C8eim][2-Op] (Ph-C8eim = 1-N-ethyl-3-N-octyl-2-phenylimidazolium) with weaker cation-anion interactions exhibited a significant increase in the CO2 uptake capacity, and extremely high capacities of 1.69 and 1.83 mol CO2 per mol IL could be achieved at 30 and 20 °C, respectively. The study presented here would be helpful for further designing novel and effective ILs for advancing CO2 capturing performance.

Functionalized ionic liquid membranes for CO2 separation

It is imperative to develop efficient, reversible and economic technologies for separating CO₂ which mainly comes from flue gas, natural gas and syngas.

Reinventing Design Principles for Developing Low-Viscosity Carbon Dioxide-Binding Organic Liquids for Flue Gas Clean Up

Anthropogenic CO₂ emissions from point sources (e.g., coal fired-power plants) account for the majority of the greenhouse gases in the atmosphere. Water-lean solvent systems such as CO₂ -binding organic liquids (CO₂ BOLs) are being developed to reduce the energy requirement for CO₂ capture. Many water-lean solvents such as CO₂ BOLs are currently limited by the high viscosities of concentrated electrolyte solvents, thus many of these solvents have yet to move toward commercialization. Conventional standard trial-and-error approaches for viscosity reduction, while effective, are time consuming and economically expensive. We rethink the metrics and design principles of low-viscosity CO₂ -capture solvents using a combined synthesis and computational modeling approach. We critically study the effects of viscosity reducing factors such as orientation of hydrogen bonding, introduction of higher degrees of freedom, and cation or anion charge solvation, and assess whether or how each factor affects viscosity of CO₂ BOL CO₂ capture solvents. Ultimately, we found that hydrogen bond orientation and strength is the predominant factor influencing the viscosity in CO₂ BOL solvents. With this knowledge, a new CO₂ BOL variant, 1-MEIPADM-2-BOL, was synthesized and tested, resulting in a solvent that is approximately 60 % less viscous at 25 mol % CO₂ loading than our base compound 1-IPADM-2-BOL. The insights gained from the current study redefine the fundamental concepts and understanding of what influences viscosity in concentrated organic CO₂ -capture solvents.

Simultaneous CO2 and SO2 capture by using ionic liquids: a theoretical approach

Density functional theory (DFT) methods were used to analyze the mechanism of interaction between acidic gases and ionic liquids based on the 1-ethyl-3-methylimidazolium cation coupled with five different anions.

Enhanced CO2 uptake by intramolecular proton transfer reactions in amino-functionalized pyridine-based ILs

This work presents a new strategy for the promotion of CO₂ uptake by an intramolecular proton transfer reaction in amino functionalized hydroxypyridine based anions.

Tuning the Carbon Dioxide Absorption in Amino Acid Ionic Liquids

One of the possible solutions to prevent global climate change is the reduction of CO2 emissions, which is highly desired for the sustainable development of our society. In this work, the chemical absorption of carbon dioxide in amino acid ionic liquids was studied through first-principles methods. The use of readily accessible and biodegradable amino acids as building blocks for ionic liquids makes them highly promising replacements for the widely applied hazardous aqueous solutions of amines. A detailed insight into the reaction mechanism of the CO2 absorption was obtained through state-of-the-art theoretical methods. This allowed us to determine the reason for the specific CO2 capacities found experimentally. Moreover, we have also conducted a theoretical design of ionic liquids to provide valuable insights into the precise tuning of the energetic and kinetic parameters of the CO2 absorption.