Solvents For CO2 Capture Research Articles

Bench-scale CO2 capture using water-lean solvent of 2-(ethylamino) ethanol, 1-methyl-2-pyrrolidinone, and water

Water-lean amine are promising solvent for CO2 capture to significantly reduce regeneration energy. However, existing water-lean solvent hasn’t been put into commercial application due to high reaction heat, slow CO2 absorption rate, and high amine volatility of amine. In this paper, amines with one secondary amino (—NH), one hydroxyl (—OH), and carbon chain length between 3 and 6 (C3-C6) in structure were preferred for water-lean solvent in the light of amine structure–activity relationship. 2-(ethylamino) ethanol (EMEA) dissolving into 1-methyl-2-pyrrolidinone (NMP) and water were favorable water-lean solvent for CO2 capture, and EMEA/NMP was tested in a bench-scale platform. EMEA/NMP solvents have equivalent CO2 removal efficiencies, and 40–69% lower regeneration energy compared to blended amines and MEA solvents. The lower regeneration energy of EMEA/NMP results from lower water vapor ratio, lower reaction heat, and lower heat capacity. Viscosity of EMEA/NMP at rich loading is 6.92–11.11 mPa·s at 40℃. Increased stripper temperature increases CO2 removal efficiency by decreasing lean loading in EMEA/NMP solvents. CO2 desorption dominates mass transfer in stripper at low temperature while water evaporation dominates at high temperature. The lowest regeneration energy obtained with 5.0 M EMEA/NMP at liquid/gas ratio of 10.5 L/m3 and stripper temperature of 80℃ was 0.99 kWh/kg CO2 (equivalent to 3.6 GJ/tCO2), which is 69% lower than that of 5 M MEA. EMEA/NMP has an increasing amine emission from 109 to 1891 mg/m3 as absorber temperature increases from 34℃ to 54℃. Advanced processes would be employed for volatile amine emission control in future study.

Generalized viscosity model based on free-volume theory for amino acid salt solutions as green CO2 capture solvents

Green processes that use environmentally friendly materials have gained significant attention, in particular in the fuel processing section. Alkaline salts of natural amino acids (NAAs), known as NAA salt solutions (NAASs), have significant potential to replace conventional solvents for achieving greener CO2 capture. Thermophysical properties, including the viscosity of NAASs, are essential for developing processes and their optimization. This study aims to develop a generalized theoretical model derived from free-volume theory (FVT) for estimating the viscosity of NAASs. Four different cases for parameter regression were applied to the largest viscosity databank investigated thus far (19 NAAs, three alkaline compounds, 29 NAASs, and 2039 data points), and the performance of the model using the parameters from the cases was evaluated. The highest accuracy was achieved (average absolute relative deviation percentage (AARD) = 1.54 %, average relative deviation percentage (ARD) = 0.09 %, R-squared (R2) = 0.9969) in the concentration- and solution-specific cases, but many parameters were required for the whole databank. In contrast, the most general case using global parameters resulted in the least number of parameters (six adjustable parameters) and showed reasonable accuracy (AARD = 10.42 %). A specific case in which the model parameters were obtained from each NAAS with a simple modification of the barrier energy parameter (α) yielded a higher accuracy (AARD = 4.12 %, ARD = 0.53 %, R2 = 0.9606) with a smaller number of parameters for the entire databank. The results demonstrated that the FVT is capable of modeling the viscosities of NAASs and can thus be employed for the simulation and optimization of thermophysical properties.

Enhancing CO2 Transport Across a PEEK-Ionene Membrane and Water-Lean Solvent Interface.

Efficient direct air capture (DAC) of CO2 will require strategies to deal with the relatively low concentration in the atmosphere. One such strategy is to employ the combination of a CO2 -selective membrane coupled with a CO2 capture solvent acting as a draw solution. Here, the interactions between a leading water-lean carbon-capture solvent, a polyether ether ketone (PEEK)-ionene membrane, CO2 , and combinations were probed using advanced NMR techniques coupled with advanced simulations. We identify the speciation and dynamics of the solvent, membrane, and CO2 , presenting spectroscopic evidence of CO2 diffusion through benzylic regions within the PEEK-ionene membrane, not spaces in the ionic lattice as expected. Our results demonstrate that water-lean capture solvents provide a thermodynamic and kinetic funnel to draw CO2 from the air through the membrane and into the bulk solvent, thus enhancing the performance of the membrane. The reaction between the carbon-capture solvent and CO2 produces carbamic acid, disrupting interactions between the imidazolium (Im+ ) cations and the bistriflimide anions within the PEEK-ionene membrane, thereby creating structural changes through which CO2 can diffuse more readily. Consequently, this restructuring results in CO2 diffusion at the interface that is faster than CO2 diffusion in the bulk carbon-capture solvent.

Multi-Criteria Screening of Organic Ethanolamines for Efficient CO2 Capture Based on Group Contribution Method

Amine solvent has attracted much attention due to its high CO2 capture level and wide application range, but its high energy consumption for recycling restricts its large-scale commercialization. In this work, a multi-objective optimization technology based on the group contribution method was used to select potential amine solvents for CO2 capture. This computer-aided molecular design method considers the thermodynamic and kinetic properties of the candidate solvent and evaluates the influence of relevant parameters on solvent performance. Compared with previous experimental methods used to optimize solvent, this method selects potential solvents from a large number of solvent databases based on group contribution. Firstly, a corresponding classification database was established for various kinds of amine solvents. Then, the traditional experiments were used to verify and screen solvents. At the same time, the method was applied to 31 amine absorbents concerning solubility, molar volume, surface tension, heat capacity, viscosity, pKa, saturated vapor pressure, and so on, and seven solvents were found to have comparable performance to MEA, with higher absorption rates and solubility. This method provides guidance for screening CO2 capture absorbents with economic viability, high efficiency, fast absorption rates, and low regeneration energy consumption.

CO2 capture with green ionic liquid and deep eutectic solvent: A comparative study

Increasing the greenhouse gases in the atmosphere, mainly from human activities leads to the global warming phenomenon and poses a serious threat to life on the earth.Hence, there is a pressing need to mitigate greenhouse gases emission and overcome global warming. It is proven that Ionic liquids (ILs) and deep eutectic solvents (DESs) are fruitful materials to capture gases and reduce their emission. Here, we investigate the environmentally friendly and cost-effective cholinium geranate ([Cho][Ger]) IL and cholinium geranate:geranic acid ([Cho][Ger]:Ger acid) DES, for carbon dioxide (CO2) capture. To this end, the density functional theory (DFT) and molecular dynamics (MD) simulation approaches are employed to provide quantitative microscopic insight into the interactions between CO2 and IL/DES. The adsorption energies of IL…CO2 and DES…CO2 are explored through the DFT calculations and show stronger interaction between the IL…CO2 than DES…CO2. The MD simulation analyses including density profile, non-bonded energy, radial distribution function (RDF), and spatial distribution function (SDF) affirm the stronger interaction between the IL…CO2 than DES…CO2. Meanwhile, the DFT and MD simulation results reveal the strongest interaction between CO2 and [Ger] - anion of both IL and DES. Furthermore, the minimum potential of mean force (PMF) of CO2 at the IL-air interface represents the favorable adsorption of CO2 on IL. Overall, our molecular level findings which are not accessible through the experimental approaches could help experimentalists find high-efficient solvents for CO2 capture.

Evaluation of novel aqueous piperazine-based physical-chemical solutions as biphasic solvents for CO2 capture: Initial absorption rate, equilibrium solubility, phase separation and desorption rate

Novel aqueous piperazine-based physical–chemical solutions were proposed as promising liquid–liquid biphasic solvents for energy-efficient CO2 capture in order to enhance the absorption and desorption performance. Various phase-change systems including Piperazine (PZ), 1-(2-aminoethyl) piperazine (AEP), methyldiethanolamine (MDEA), sulfolane, 1-propanol and water with different concentration ratios were investigated comprehensively in terms of initial absorption rate, equilibrium solubility, phase splitting and desorption rate in the present work. Experimental results indicated that with the aid of organic solvents, PZ and AEP were proved to be promising candidates to accelerate the initial absorption and desorption rates, as well as enhance the CO2 absorption capacity due to their excellent reaction kinetics. The tunable phase separation property could be achieved by varying the concentration ratios of amine/organic solvent. After achieving equilibrium, the two liquid–liquid phases would not return back to one homogeneous liquid phase. Among these biphasic solvents, aqueous 2.5 M PZ + 2.5 M sulfolane with a large CO2 loading 0.85 mol CO2/mol amine at the phase change point was the optimal choice owing to good phase separation and great absorption and desorption properties. Compared to aqueous 2.5 M PZ single solvent, it demonstrated a 16% higher initial absorption rate, 9% larger CO2 absorption capacity and double desorption rate. This research provided a potential alternative absorbent for CO2 capture.

CO2 absorption in blended amine solvent: Speciation, equilibrium solubility and excessive property

Mixing different amines is a common method to develop better solvents for CO2 capture. As the mixing provides more adjustability on the solvent properties, it introduces complex interaction between dissimilar amine molecules who may perform diverse role in the reactions. Here we studied CO2 absorption in monoethanolamine (MEA), methyldiethanolamine (MDEA) and their mixtures thereof. The speciation profiles along with CO2 loading were provided via NMR to reveal the competition/coordination of MEA and MDEA in participating the key reactions that drove CO2 absorption (i.e. carbamate formation and amine protonation). Furthermore, the CO2 loading of the solvents were measured under equilibrium for various temperature, CO2 partial pressure. The excessive CO2 loading was firstly introduced to analyze the loading data regarding the solvent composition. Accordingly, an excessive property model was applied for data correlation. The calculated CO2 loading agreed well with experimental data with average absolution relative deviation of 1.7%.

Technical performance and environmental assessment of an ionic liquid-based CCS process for hydrogen production

Hydrogen (H2) production combined with carbon capture and storage (CCS) is anticipated to be an important technology contributing to reduce the carbon footprint of current fossil-based H2 production systems. This work addresses for the first time the techno-environmental assessment of a CCS process based on the ionic liquid [Bmim][Acetate] for H2 production by steam methane reforming (SMR) and the comparison to conventional amine-based systems. Two different SMR plants using MDEA or [Bmim][Acetate] for CO2 capture were rigorously modelled using Aspen Plus to compute material and energy needs and emissions. Literature and simulation results were then used to perform a life cycle impact assessment (LCIA) of these processes based on the ReCiPe model. Solvent synthesis, CCS process and hydrogen production stages were considered for the cradle-to-gate analysis. Results showed that although [Bmim][Acetate] is a priori more harmful to the environment than amines (in a kg-to-kg comparison), LCIAs carried out for both CCS processes showed from 5 to 17 % lower environmental impacts values for all estimated categories when using [Bmim][Acetate] due to a 9.4 % more energy-efficient performance than MDEA, which also reduced a 17.4 % the total utility cost. Indeed, if a typical amine loss rate of 1.6 kg/tCO2 is assumed, the values of the environmental impacts increase up to 14 % for the IL-based CCS plant, but still maintaining its favorable results over MDEA. As consequence, the SMR plant with the IL-based CCS system exhibited 3–20 % lower values for most of the studied impact categories. These results contribute to shed some light on evaluating the sustainability of ILs with respect to conventional solvents for CO2 capture and to guide the synthesis of new more sustainable ILs but also, they would be used to compare the environmental burdens from the synthesis and process performance of other promising ILs for CO2 capture that are not environmentally assed yet.

Comparative Study for the Absorption of Carbon Dioxide in Aqueous Amine Solvents for Enhanced Loading

Aims: The current study aimed to investigate the CO2 absorption capacity of the aqueous alkanolamine, including primary, secondary, tertiary, and sterically hindered amines and polyamines, i.e., monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA) and 2- amino-2-methyl-1-propanol (AMP), tetraethylenepentamine (TEPA), triethylenetetramine (TETA), 3- (Methylamino)propylamine (MAPA), and diethylenetriamine (DETA) at 40, 60, and 80°C at 1.1 bar. Methods: An increase in reaction temperature caused a decrement in CO2 loading across the board for all solvents. The trend of CO2 loading was TEA < MEA < DEA < AMP < MAPA < DETA < TETA < TEPA at 40 ºC, TEA < DEA < MEA < AMP < MAPA < DETA < TETA < TEPA, at 60ºC and TEA < DEA < AMP < MEA < MAPA < DETA < TETA < TEPA at 80ºC. Results: The results indicated that TEPA has great potential to be utilized as an energy-efficient and non-corrosive solvent for CO2 capture since it has outperformed all other aqueous amine solvents in this present study. Furthermore, the CO2 loading of sterically hindered amine (AMP) at the same temperature was found to be higher than primary, secondary, and tertiary amines. Heat of absorption (Δ Η abs) was also determined to gauge the energy requirement to regenerate absorbents for cyclic loading from an economic viewpoint. Conclusion: DETA has the highest Δ Η abs = 84.48 kJ/mol. On the contrary, the long-chain tertiary amine TEA resulted in the least Δ Η abs = 40.21 kJ/mol, among all other solvents. Whereas the sterically hindered amine (AMP) was observed to possess mid-range Δ Η abs, i.e., 58.76 kJ/mol. Among all selected solvents, polyamines showed higher Δ Η abs than other conventional amines pertaining to the precedence of TEA<AMP<DEA< MEA<TETA<TEPA<MAPA<DETA.

A novel binary solid-liquid biphasic functionalized ionic liquids for efficient CO2 capture: Reversible polarity and low energy penalty

Ionic liquids (ILs) solid-liquid biphasic solvents for CO2 capture have the advantages of high CO2 loading and low energy consumption, and their phase change behavior was regulated via phase separation agents. However, phase separator agents exhibit bottlenecks in terms of volatility loss and high-rich phase viscosity. A novel “reversible polarity” functionalized ionic liquids (isophorone diamine-imidazole, [IPDAH][Im]) was innovatively proposed in this work, which featured solid-liquid phase change behavior upon CO2 absorption in water in the absence of a phase separation agent. After saturated absorption, CO2 products were enriched into the lower phase and precipitated as a white crystalline powder with 91 % of the total CO2 loading (1.15 mol mol−1) but only 60 % of the total volume. Products after thermal desorption (393.15 K), maintaining 80 % of its initial loading after the sixth regeneration cycle. Based on the results of experimental characterization and theoretical calculation, [IPDAH][Im] possessed reversible polarity, and its initial polarity was consistent with that of water. After absorption, [IPDAH][Im] interacted with CO2 to form products whose polarity diminishes, resulting in the associated phase transition; after desorption, the high polarity is restored. The products existed as ion pairs (ILsCOO−-ILsH+), as evidenced by strong van der Waals interaction, and electrostatic attraction. Strong hydrogen bonding forces between the products and the Hansen solubility parameter, as well as the high lattice energy, led to the self-agglomeration formation of the products in water, resulting in the development of a solid powder product. The heat duty of [IPDAH][Im]–H2O was 1.23 GJ ton−1 CO2, which was approximately 67 % less than that of monoethanolamine (MEA; 3.77 GJ ton−1 CO2), signifying a major potential for application in CO2 capture.

Performance of hydrophobic physical solvents for pre-combustion CO2 capture at a pilot scale coal gasification facility

Here, we present the first pilot plant data for hydrophobic physical solvents for CO2 and H2S removal from coal-derived H2-rich syngas. Four physical solvents were tested under pre-combustion CO2 capture conditions at bench scale and pilot plant scale: one baseline hydrophilic solvent and three hydrophobic solvents. The solvents were: (1) polyethylene-glycol-dimethyl ether (PEGDME), a hydrophilic solvent analog for the commercial process Selexol, (2) tributyl- phosphate (TBP), a commercially available hydrophobic solvent, (3) polyethylene glycol-poly(dimethylsiloxane) (PEG-PDMS-3), and (4) diethyl sebacate (CASSH-1), a novel, computationally screened hydrophobic solvent developed by the National Energy Technology Laboratory (NETL). All solvents were studied under pure gas (CO2/N2/H2/CH4) equilibrium conditions at NETL followed by pilot plant testing with syngas at the University of North Dakota Energy & Environmental Research Center (UND EERC). Long term performance of CASSH-1 and PEDGME was then assessed with results compared to process simulation predictions. Within experimental uncertainties, all solvents showed comparable CO2 absorption performance at above room temperature operation while the hydrophobic solvents had limited water uptake and low vapor pressure, which alleviates concerns related to corrosion, water absorption, and solvent loss to evaporation. These results indicate low viscosity, low vapor pressure hydrophobic solvents are a promising option for lower cost CO2 capture from high pressure syngas applications.

Enabling the direct solution of challenging computer-aided molecular and process design problems: Chemical absorption of carbon dioxide

The search for improved CO2 capture solvents can be accelerated by deploying computer-aided molecular and process design (CAMPD) techniques to explore large molecular and process domains systematically. However, the direct solution of the integrated molecular-process design problem is very challenging as nonlinear interactions between physical properties and process performance render a large proportion of the search space infeasible. We develop a methodology that enables the direct and reliable solution of CAMPD for absorption–desorption processes, using the state-of-the-art SAFT-γ Mie group contribution approach to predict phase and chemical equilibria. We develop new feasibility tests and show them to be highly efficient at reducing the search space, integrating them in an outer-approximation algorithm. The framework is applied to design an aqueous solvent and CO2 chemical absorption–desorption process, with 150 CAMPD instances across three case studies solved successfully. The optimal solvents are more promising than those obtained with sequential molecular design approaches.

A Membrane Contactor Enabling Energy-Efficient CO2 Capture from Point Sources with Deep Eutectic Solvents

We demonstrate a scalable and energy-efficient hollow fiber membrane contactor (HFMC)-based process using a green solvent for CO2 capture. This process uses a deep eutectic solvent (DES) in an HFMC to provide close interfacial interactions and contact between the DES and CO2. This approach overcomes disadvantages associated with direct absorption in DES and could potentially be applied to a variety of solvent-based CO2 capture methods. Commercial low-cost polymer hollow fiber membranes (e.g., microporous polypropylene) were evaluated for CO2 capture with reline, a prototypical DES. Single-gas measurements showed that the DES-based polypropylene HFMC can capture and separate CO2 while rejecting N2. From a mixed gas containing 50 mol % N2 and 50 mol % CO2, the DES-based HFMC separated CO2 with a purity of 96.9 mol %. The effect of several process parameters including solvent flow rate, pressure, and temperature on the CO2 separation performance was studied. The flux of the recovered CO2 was 67.43 mmole/m2/h at a feed pressure of 4 bar. In situ Fourier transform infrared (FTIR) measurements combined with density functional theory (DFT)-based molecular dynamics simulations revealed that reline absorbs CO2 by physical absorption without forming a new chemical compound, and CO2 separation by reline occurs via the pressure swing mechanism. This research provides fundamental insights about physical solvent-based separation processes and a pathway toward practical deployment.

Impact of Hydrogen Bonds on CO2 Binding in Eutectic Solvents: An Experimental and Computational Study toward Sorbent Design for CO2 Capture

Choline-based amino acid ionic liquids with anions glycinate, β-alaninate, phenylalaninate, and prolinate were synthesized and mixed with ethylene glycol to form lower-viscosity benign eutectic solvents for CO2 capture. The highest capacity measured was 0.7 moles of CO2 per mole of ionic liquid (2 moles CO2 per kg solvent) for a 1 to 2 mole ratio mixture of choline prolinate to ethylene glycol at 1 bar of CO2 and 25 °C. Under 5000 ppm of CO2, half of this capacity was realized. Through a combined study of quantitative 13C NMR spectroscopy, molecular dynamics simulations and density functional theory calculations, we show that hydrogen bonding in the eutectic solvent prevents proton-transfer between prolinate anions upon CO2 absorption, which occurs in the absence of ethylene glycol and deactivates binding sites. Blocking this proton transfer leads to a higher binding capacity compared to neat choline prolinate. This work demonstrates the impact of hydrogen bonding on the CO2 binding mechanism and energetics, as well as physical and thermal properties in eutectic solvents, thus addressing an unmet need and informing future studies on the development of benign sorbents for capturing CO2 from dilute streams.

Experimental Analysis of Reaction Heat of CO2 Absorption of Phase Change Absorber AEP-DPA at Low Partial Pressure

The reaction heat of CO2 absorption by organic amines is directly related to the regenerative heat consumption of absorbers. Therefore, it is necessary to study and determine the heat of absorption reaction and heat of regeneration reaction of CO2 capture solvent before its industrial validation and application. According to the law of thermodynamics, a computer model of the heat of absorption reaction and desorption reaction is established and verified. The heat of reaction of the AEP-DPA phase transition absorption system was studied under different ratios, absorption temperatures, reaction concentrations and reaction pressures. The heat of reaction increases with concentration and decreases with pressure. The reaction heat of the AEP-DPA phase transition absorption system and MEA were compared. The optimum reaction conditions were as follows: AEP-DPA ratio 6:4, absorption temperature 40 °C. The reduction rate of absorption heat and regenerative heat of the AEP-DPA phase change absorption system is more than 35% and 31%, respectively.

Cost and Heat Integration Analysis for CO2 Removal Using Imidazolium-Based Ionic Liquid-ASPEN PLUS Modelling Study

The recent advancement in efficient and recoverable CO2 capture solvents has been stimulated by the environmental harm resulting from the accumulation of greenhouse gases. Ionic liquids (ILs) and IL-based solvents have given rise to a novel method of CO2 collection that is highly efficient, economical, and environmentally benign. However, there is a lack of knowledge about the implementation of this process on a wider scale, and it has limitations, including high solvent costs. This simulated study shows that [EMIM][NTF2] can remove up to 99.4% of the CO2 from industrial waste effluents using three distinct compositions. Following an economic study using a 20-year plant life estimate, with a plant capacity of 4000 kg/h (206.165 kmol/h) for the raw mixed stream flow (inlet) and a maximum CO2 capacity of 38.1 kmol/h, it was determined that the process’s overall annualized cost was USD 2.1 million with operating expenses being USD 1.8 million. The Aspen Activated Energy Analysis’s recommendation of adding a heat exchanger, with a payback year of 0.0586 years, a 23.34 m2 area, and potential energy cost savings of USD 340,182/Year was also implemented successfully. These findings propose a conceptual framework for the development of novel ionic liquids for CO2 capture. It also demonstrates that sustainable [EMIM][Tf2N]-based absorption techniques for CO2 capture have the potential to be an industrial technology.

Pilot test of water-lean solvent of 2-(ethylamino) ethanol, 1-methyl-2-pyrrolidinone, and water for post-combustion CO2 capture

Water-lean solvent for post-combustion CO2 capture is promising to significantly reduce regeneration energy. It hasn’t been put into commercial application due to unsolved challenges including water balance issue, increased viscosity, and high volatility. Even though numerous water-lean solvents were developed in laboratory, rare of them were tested in pilot scale. Water-lean solvent of 2-(ethylamino) ethanol (EMEA) dissolving into 1-methyl-2-pyrrolidinone (NMP) and water was tested in a CO2 capture pilot with flue gas rate of 280 m3/h. Effects of liquid/gas ratio and reboiler steam rate on CO2 removal efficiency, regeneration energy, lean/rich heat exchanger performance, and volatile amine emission were investigated. Water-lean EMEA achieved CO2 removal efficiency greater than 90 % and the lowest regeneration energy of 2.3 GJ/tCO2, which is 43 % lower than that of 5 M MEA. Water-lean EMEA showed significantly reduced latent heat, greater CO2 capacity, and lower reaction heat (secondary amino) than aqueous MEA and amine blends. It was found that water-lean EMEA regeneration in stripper had extremely lower lean loading (0.1–0.5 mol CO2/L) than aqueous MEA and amine blends, which enables a faster CO2 absorption rate in absorber and a greater CO2 capacity, but also causes larger volatile amine emission. Volatile amine emission after water wash was 110–380 mg/m3. 13C NMR spectrum suggested amine carbamate dominated CO2 absorption products. Due to that increased viscosity decreases heat transfer coefficient (h), lean/rich heat exchanger temperature difference (ΔT) for water-lean EMEA (6.5–7.5℃) was greater than MEA (3.5-5℃) and amine blends (5-6℃), yet smaller than biphasic solvent (8-9℃). A negative power (-0.614) function relation between h and viscosity was fitted and can be further used to normalize sensible heat.

Synthesis and Properties of 2-Halo-1,3-diether-propanes: Diversifying the Range of Functionality in Glycerol-Derived Compounds

Synthesis of value-added chemicals from glycerol derivatives has been of real interest due to the excess volumes of glycerol resulting from biofuel production. Previously, we have demonstrated the controlled synthesis of symmetric and asymmetric 1,3-diether-2-propanol compounds bearing glycerol skeletons, which, in addition to potential applications as CO2 capture solvents, are also versatile intermediates for a number of further chemical transformations. Here, we demonstrate the conversion of these compounds to corresponding 2-halo-1,3-diethers as a means of further diversifying the range and properties of glycerol-derived compounds. Thermophysical properties of these compounds (density, molar volume, and viscosity) were measured over a temperature range of 20–80 °C. The experimental work was augmented by theoretical calculations of density, viscosity, vapor pressure, and dipole moment for each of the synthsized compounds as well as additional species with similar structures that have not yet been synthesized. The data obtained in this work provide a useful guide for valorization of glycerol in the form of new solvents and building blocks for value-added chemicals.

New water-based nanocapsules of poly(diallyldimethylammonium tetrafluoroborate)/ionic liquid for CO2 capture

Encapsulated ionic liquids as green solvents for CO2 capture are reported in this work. We present a novel combination of water-based poly(ionic liquid) and imidazolium-based ionic liquids (Emim[X]). Poly(diallyldimethylammonium tetrafluoroborate)/Emim[X] capsules were developed for the first time using Nano Spray Dryer B-90. Capsules were characterized by FTIR, SEM/EDX, TEM, TGA, DSC, CO2 sorption, and CO2/N2 selectivity, CO2 sorption kinetic and recycling were also demonstrated. Comparing the capsules reported in this work, the combination of poly(diallyldimethylammonium tetrafluoroborate) and the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (P[DADMA]/BF4) showed great potential for CO2 capture and CO2/N2 separation, providing higher results (53.4 mg CO2/g; CO2/N2 selectivity: 4.58).

Investigation of the CO2 capture behavior in multiple-site natural deep eutectic solvents

The sustainable development of carbon dioxide (CO2) resource requires the realization of green and efficient capture for the fossil fuel CO2. However, the high operation costs and biological toxicity have hampered the application. Natural deep eutectic solvents (NADESs) are efficient and green CO2 absorbent. In this manuscript, kinds of amino acid-based NADESs were prepared successfully to improve the absorption efficiency of CO2 capture solvent. The chemical structure of NADESs was characterized, and the thermal stability was also measured. The CO2 capture behavior of amino acid-based NADESs was investigated. With multi-reactive sites, unstable stage and more accessibility of alkyl structure on HBA (alkyl amino acids and aromatic amino acids, especial L-Ary), and less electronegativity on HBD (EG), L-Arg/EG NADESs had lower solvation effect (β value, 1.286) and reduced viscosity (48.33 mpa.s at 60 ºC). It behaved better absorption capacity. The optimized conditions by single-factor analysis and Response surface methodology were L-Arg/EG at the mole ratio of 1:5, 30 °C and 200 mL/min, and the absorption could reach 0.81 molCO2/kgNADESs. Additionally, an insight into the reaction mechanism was investigated. It was found that hydrogen-bond structure played an important role in CO2 capture. The broken of H-O···H-N formed by amino acids and ethylene glycol promoted the formation of new bonds of -(O=)C···NHR between L-Arg/EG and CO2, thus achieved higher CO2 capture. The investigated proved that the green solvent amino acid-based NADESs could be efficient absorbents for CO2 capture.