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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Conversion of sugars to ionic liquids

Disclosed herein are methods for preparing sugar compositions. The methods include: i) forming a mixture including polysaccharide biomass and an ionic liquid solution, wherein the ionic liquid solution contains water and an ionic liquid, and the ionic liquid contains a) a cation and b) a sugar acid anion or a ketoacid anion; ii) maintaining the mixture under conditions sufficient to dissolve at least a portion of the polysaccharide present in the polysaccharide biomass; iii) adding at least one glycoside hydrolase to the mixture; and iv) maintaining the mixture containing the glycoside hydrolase under conditions sufficient to hydrolyze at least a portion of the dissolved polysaccharide, thereby forming the sugar compositions. The sugar compositions contain at least one monosaccharide or oligosaccharide. New sugar-based ionic liquids are also described.

Gladden, John M.↗
DOE OSTI2024

Rheology characterization of ionic liquids under high pressure and high temperature

Ionic liquids (ILs) are liquid salts that exist at or below ambient temperatures and are composed of ion pairs. They offer promising alternatives to toxic, hazardous, highly flammable, and volatile solvents in various applications such as solution preparation, dispersion, gel formation, composites, and polymer melts. ILs possess unique and interesting characteristics, including excellent chemical and thermal stability and low vapor pressures. Understanding the rheological properties of ILs is essential to optimizing IL performance. This paper presents a comparative analysis of the rheological properties of two ionic liquids, Nsingle bondHexylpyridinium tetrafluoroborate (HPyBF4) and Nsingle bondHexylpyridinium bromide (HPyBr), under different shear rates, temperatures, and pressures. Rheological measurements were performed under varying controlled pressure and temperature conditions. The experimental investigation covered a pressure range of 689–12,411 kPa [100–1800 psi] and a temperature range from room temperature up to 522 kelvin (K) [480°F]. The primary objective is to explore and compare the flow behavior and viscoelastic characteristics of HPyBF4 and HPyBr under high-pressure and high-temperature conditions. The experimental data showed that HPyBF4 and HPyBr exhibited shear-thinning behavior, and pressure had an insignificant effect on rheology compared to the temperature effect. Under the same testing conditions, HPyBr showed higher shear stress and viscosity than HPyBF4. This research significantly contributes to the improved understanding of the rheological behavior of these specific ionic liquids and their suitability for diverse industrial and scientific applications, particularly in high-pressure and high-temperature environments.

15 GEOTHERMAL ENERGY↗
DOE OSTI2020

Revealing the Structural Evolution of Green Rust Synthesized in Ionic Liquids by In Situ Molecular Imaging

Abstract Ionic liquids are green solvents that have wide applications in material synthesis, catalysis, and separation. A model switchable ionic liquid (SWIL) consisting of 1,8‐diazabicycloundec‐7‐ene (DBU) and 1‐hexanol with carbon dioxide (CO 2 ) as the trigger gas is chosen to synthesize nanocrystalline green rust. Under anoxic conditions, by adding iron (II) acetate (Fe(C 2 H 3 O 2 ) 2 ) and methanol to the degassed SWIL, a nanoparticulate green rust with carbonate (nano‐GR) is synthesized. More importantly, the molecular structural change of the ionic liquid resulting in green rust crystallines is first characterized using in situ liquid using time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) coupled with the system for analysis at the liquid vacuum interface (SALVI), a vacuum compatible microfluidic reactor in this work. Dimers and ionic clusters consisting ferric and ferrous ions are identified in liquid ToF‐SIMS spectra. Spectral principal component analysis is used to confirm that these ion pairs including dimers and cluster ions are different from nonionic liquids. The results show that liquid ToF‐SIMS can be a useful tool to study complex liquids at the molecular level providing insights into predicative synthesis of nanomaterials using environmentally friendly green solvents and giving unique visualization of the evolving material interface due to nucleation.

Shen, Yanjie↗
DOE OSTI2020

Fluorinated ionic liquids for battery electrolytes

An ionic liquid comprising a cationic chemical species and an anionic chemical species. The cationic chemical species comprising a nitrogen containing moiety and a partially fluorinated alkyl chain moiety, wherein the partially fluorinated alkyl chain moiety is bonded to a nitrogen atom of the nitrogen containing moiety. The ionic liquid can be used as an electrolyte, as an additive to an organic solvent, as a lubricant, as a hydrophobic coating, as a treatment for fluorinated pollutants, as an electrolyte for sensor applications, as a stabilizing additive for existing battery electrolytes, and as an emulsifier.

25 ENERGY STORAGE↗
DOE OSTI2021

Order-disorder in room-temperature ionic liquids probed via methyl quantum tunneling

Room-temperature ionic liquids are promising candidates for applications ranging from electrolytes for energy storage devices to lubricants for food and cellulose processing to compounds for pharmaceutics, biotransformation, and biopreservation. Due to the ion complexity, many room-temperature ionic liquids readily form amorphous phases upon cooling, even at modest rates. Here, we investigate two commonly studied imidazolium-based room-temperature ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, as well as their mixtures, to demonstrate how the complex interplay between the crystalline and amorphous phases is affected by the processing conditions, such as thermal history, liquid mixing, and applied pressure. We show that quantum tunneling in the cation methyl groups, measured by high-resolution inelastic neutron scattering, can be used to probe the order-disorder in room-temperature ionic liquids (crystalline vs amorphous state) that develops as a result of variable processing conditions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Electrochemical, thermodynamic, and physical properties of tetradecyltrihexylphosphonium ([P 6,6, 6,14 ] + ) and methyl-propyl piperidinium containing ionic liquids and their propylene carbonate solutions

Here, the viscosity, conductivity, electrochemical window and related thermodynamic properties such as excess volume and dynamic viscosity deviation of two phosphonium ionic liquids were measured and calculated for “as-supplied” and dried neat liquids and also v/v mixtures of 99/1, 95/5, 90/10, 75/25, and 50/50 of the ionic liquids with propylene carbonate (PC). Tetradecyltrihexylphosphonium dicyanamide ([P 6,6,6,14 ] + dicyanamide), Cyphos 105, and tetradecyltrihexylphosphonium bis(trifluororomethanesulfonyl)imide (called bistriflimide) ([P 6,6,6,14 ] + bistriflimide), Cyphos 109, ionic liquids were studied. Generally speaking, there were slight differences in the measured properties of the wet and dried IL solutions which were reflected in differences if the calculated properties. The measured and calculated properties were compared with those collected and derived from a piperidinium-based ionic liquid, methyl-propyl piperidinium bistriflimide. Arrhenius plots for both the viscosity and conductivity were linear, with the linearity of the Litovitz plots being slightly higher. The viscosity and conductivity of the phosphonium solutions yielded Walden Plots that differed from Walden plots of piperidinium solutions and other ionic liquid solutions. For the phosphonium based ionic liquids, the ionicity was found to increase with increasing dilution in propylene carbonate. The electrochemical windows of the ionic liquids were determined as a function of the concentration of the ionic liquid present in the solution. The size of the window generally initially decreased and then increased with the addition of PC for the [P 6,6,6,14 ] + dicyanamide ionic liquid increasing from 3.4 V in the 95/5 v/v (volume Cyphos 105) to volume of PC solvent) to 3.7 in the 50/50 dried IL case. The electrochemical windows of the dried liquids were slightly larger 3.5 V for the 95/5 v/v and 4.2 V for the 50/50 v/v Cyphos 105/PC solutions. The electrochemical window was larger and the conductivity was higher for the piperidinium IL solutions, but since the ionicity increases with dilution, the phosphonium based IL solutions may prove favorable for processes such as electrochemical reduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Biomass pretreatment with distillable ionic liquids for an effective recycling and recovery approach

Ionic liquid (IL) pretreatment methods show incredible promise for the efficient conversion of lignocellulosic feedstocks to fuels and chemicals. Given their low vapor pressures, distillation-based methods of extracting ionic liquids out of biomass post-pretreatment have historically been ignored in favor of alternative methods. We demonstrate a process to distill four acetate-based ionic liquids ([EthA][OAc], [PropA][OAc], [MAEthA][OAc], and [DMAEthA][OAc]) at low pressure and high purity that overcome some disadvantages of “water washing” and “one pot” recovery methods. Out of four tested ILs, ethanolamine acetate ([EthA][OAc]) is shown to have the most agreeable conversion metrics for commercial bioconversion processes achieving 73.6% and 51.4% of theoretical glucose and xylose yields respectively and >85 % recovery rates. Our process metrics are factored into a techno-economic analysis where [EthA][OAc] distillation is compared to other recovery methods as well as ethanolamine pretreatment at both milliliter and liter scales. In conclusion, although our TEA shows [EthA][OAc] distillation underperforming against other processes, we show a step-by-step avenue to reduce sugar production cost below the wholesale dextrose price at scale.

09 BIOMASS FUELS↗
DOE OSTI2023

Gel electrolyte composite including ionic liquid and zwitterionic polymer scaffold

A gel electrolyte composite containing a nonvolatile electrolyte and a zwitterionic polymer scaffold in which the non-volatile electrolyte is a non-lithium-containing ionic liquid, a sodium-containing ionic liquid, or a lithium-containing ionic liquid and the zwitterionic polymer scaffold is formed from one or more zwitterionic monomers only or both one or more zwitterionic monomers and one or more non-zwitterionic monomers. The zwitterionic polymer scaffold contains 8 mol % or higher of zwitterions relative to the total content of the gel electrolyte composite when the nonvolatile electrolyte is a non-lithium-containing ionic liquid, and contains 1 mol % or higher of zwitterions relative to the total content of the gel electrolyte composite when the nonvolatile electrolyte is a sodium-containing ionic liquid or a lithium-containing ionic liquid. Also disclosed are a method of preparing the above-described gel electrolyte composite and an electrochemical energy storage device containing same.

D'Angelo, Anthony J.↗
DOE OSTI2020

Equilibrium Thermodynamic Properties of Aqueous Solutions of Ionic Liquid 1-Ethyl-3-Methylimidazolium Methanesulfonate [EMIM][MeSO3]

Abstract The ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate ([EMIM][MeSO 3 ]) has been considered as a promising alternative desiccant to triethylene glycol and lithium bromide commonly used in the industry. In this paper, the water activity coefficient of this binary system was measured from 303 K to 363 K with water concentration from 18% to 92%. The interaction energies between the ionic liquid molecules ( $${g}_{22}$$ g 22 ) and between the ionic liquid and water molecules ( $${g}_{12}$$ g 12 ) for the [EMIM][MeSO 3 ]/water binary system were determined from the water activity coefficient data using the Non-Random Two-Liquid (NRTL) model. The magnitude of the interaction energy between the [EMIM][MeSO 3 ] and water molecules ( $${g}_{12}$$ g 12 ) was found to be in the range of 45~49 kJ/mol, which was about 20% larger than that between the water molecules ( $${g}_{11}$$ g 11 ) in the [EMIM][MeSO 3 ]/water system. The large ( $${g}_{12}$$ g 12 ) can explain many observed macroscopic thermodynamic properties such as strong hygroscopicity in the ionic liquid [EMIM][MeSO 3 ]. These interaction energies were used to determine the heat of desorption of the [EMIM][MeSO 3 ]/water system, and the obtained heat of desorption was in good agreement with that calculated from the conventional Clausius-Clapeyron Equation.

42 ENGINEERING↗
DOE OSTI2020

3D Volumetric Structural Hierarchy Induced by Colloidal Polymerization of a Quantum-Dot Ionic Liquid Monomer Conjugate

Hierarchically structured emissive quantum dot (CdS/CdSe) poly(ionic liquid) composites are synthesized through colloidal polymerization within a lyotropic liquid crystal, yielding a solvent-responsive nanoparticle (NP) composite possessing four ordered structural motifs. The composite is prepared by coassembling an amphiphilic ionic liquid (IL) monomer, 3-decyl-1-vinylimidazolium chloride, [C 10 VIm + ][Cl - ], and IL monomer, 3-(10-mercaptodecyl)-1-vinylimidazolium bromide surface-functionalized quantum dots, QD-[SC 10 VIm + ][Br - ], in 30 wt % water. Photo (UV)-initiated free radical polymerization serves to form a colloidal copolymer that collimates pairs of QDs within the core of large cylinders (average diameter = 21 nm and length = 422 nm), as evidenced by ultrasmall-angle X-ray scattering (USAXS). As revealed by continuous wave terahertz multispectral reconstructive 3-D imaging, the subsurface structure along the cylinder axis undergoes dynamic rearrangement between 2D hexagonal and cubic packing. The polymerized ionic liquid sheath surrounding the QDs is composed of concentric hexagonally perforated lamellae (HPL) with an interlamellar repeat distance of 3 nm, as determined by small-angle X-ray scattering (SAXS). The encapsulated QDs retain crystallinity (TEM and WAXS) and emission characteristics (photoluminescence spectroscopy, lambda(EM) = 638 nm). Phenomenological time-dependent Ginzburg-Landau calculations verify the mesoscale cylinders arise from the topological constraints imposed by the in-plane perforations of the polymerized ionic liquid as it wraps around the hard (unmalleable) spherical QDs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Comparing π‐complexation capabilities of ionic liquids containing silver(I) and copper(I) ions by headspace single drop microextraction in combination with high‐performance liquid chromatography

Selective π‐complexation capabilities of silver(I) and copper(I) ions can be effectively facilitated in ionic liquids. To understand the effects of environmental factors that influence the π‐complexation of these metal ions with analytes, techniques that employ small volumes of ionic liquid that can be readily analyzed are desired. In this study, headspace single drop microextraction coupled with HPLC is used to investigate a diverse set of environmental factors on the metal ion‐mediated complexation with aromatic compounds in ionic liquid media. Silver(I) and copper(I) bis[(trifluoromethyl)sulfonyl]imide salts were both studied by dissolving them in the 1‐decyl‐3‐methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquid and employing the mixture as extraction media for aromatic compounds. Water and acetonitrile within the sample solution were observed to interfere with the complexation of silver(I) ions and aromatic compounds, while ethylene glycol and triethylene glycol did not. The temperature and extraction times were optimized to fully facilitate the π‐complexation capabilities of metal ions in ionic liquid media. Partition coefficients between the sample headspace and metal ion were determined using a three‐phase equilibria model. Although no discernable difference in analyte partitioning between the headspace and ionic liquid solvent was observed, analyte partition coefficients to silver(I) ion tended to be greater compared to copper(I) ion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Switchable ionic liquids for biomass pretreatment and enzymatic hydrolysis

In one aspect, the present invention provides a method for preparing a sugar composition. The method includes: forming a mixture including polysaccharide biomass and an ionic liquid solution, wherein the ionic liquid solution contains water and an ionic liquid, and wherein the ionic liquid contains a dicarboxylic acid anion and a cation. The pH of the mixture is greater than or equal to about 10, and the molar ratio of the dicarboxylic acid anion to the cation is at least about 1:2. The method further includes: maintaining the mixture under conditions sufficient to dissolve at least a portion of the polysaccharide present in the polysaccharide biomass; reducing the pH of the mixture containing the dissolved polysaccharide to at least about 7; adding at least one glycoside hydrolase to the mixture having the reduced pH.

Liszka, Michael↗
DOE OSTI2021

Molecular dynamics simulations of a dicationic ionic liquid for CO 2 capture

A dicationic ionic liquid ([DBU-PEG][Tf 2 N] 2 ) was studied using classical molecular dynamics simulations to examine its structural and gas separation properties. The dication was designed in an attempt to improve CO 2 solubility by means of tuning the cation-anion interactions of the ionic liquid (IL). The computational model was compared to experimentally obtained density, viscosity, and powder X-ray diffraction spectra. The structure of the IL was further investigated with radial distribution functions and free volume analysis through cavity distributions. It was found that the shape and charge distribution of the dication enhances CO 2 interaction: the CO 2 molecule is hugged by the dication along the PEG linker and close to one of the cationic ends. Here, the geminal design of the dication allows for strong interaction with CO 2 , showing promise as a means of carbon capture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Ionic liquids for carbon capture

This article covers cutting-edge research in ionic liquid-based materials and their impact on carbon capture. Ionic liquids boast high thermal stability, low vapor pressure, and great tunability. They can be deployed as either sorbents or supported liquid membranes for carbon capture and other gas separations. Absorption of CO 2 in ionic liquids can be achieved via physisorption or chemisorption, depending on the strength of the interaction. For physisorption, both CO 2 -anion and cation–anion interactions are important factors in dictating CO 2 solubility. For chemisorption, the reactivity with CO 2 can be tuned by the basicity of the anion while the stability of the ionic liquid can be enhanced by controlling the cation. Marrying ionicity of ionic liquids with porosity leads to novel porous ionic liquids that feature unique properties for facilitating gas transport, while interfacing ionic liquids with microporous membranes allow the ions to gate the pores for selective gas transport. Further, composite materials of ionic liquids with crystalline materials such as metal–organic frameworks offer scalable heterogeneous interfaces to promote selectivity. Future opportunities include controlling the interaction with CO 2 and its transport at the charged or electrified interface with the ionic-liquid electric double layer, as well as combining CO 2 capture and conversion with ionic liquids.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Amine functionalized supported ionic liquid membranes (SILMs) for CO 2 /N 2 separation

Supported ionic liquid membranes (SILMs), containing aprotic N-heterocyclic anion ionic liquids (AHA ILs) in an inorganic inert support, exhibit CO 2 /N 2 permselectivity values as high as 640 at 35.0 °C and 0.03 bar CO 2 , which represents conditions similar to post-combustion carbon capture (PCCC) from a natural gas power plant. A Fickian model fit to the experimental data estimates CO 2 permeability at direct air capture (DAC) conditions of 10,400 barrer and a CO 2 /N 2 permselectivity of 4000 for the best performing IL, triethyl(octyl)phosphonium 4-bromopyrazolide ([P 2228 ][4-BrPyra]). The most important criterion for high selectivity is a large equilibrium constant for binding between the IL and CO 2 , which results in high CO 2 solubility. ILs with smaller molar volumes and with no fluoroalkyl chains enhance N 2 rejection. As a result, low viscosity and high IL molar density also enhance CO 2 /N 2 permselectivity and CO 2 permeance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Enhancing the capacitive performance of microporous materials with protic ionic liquids

Classical density functional theory (cDFT) is used to investigate the electrosorption of protic ionic liquids in porous electrodes within the framework of a coarse-grained model. The purpose of this study is to clarify the capacitive behavior of protic ionic liquids in confined geometry. Previous studies have indicated that thermodynamic properties (e.g., capacitance, phase behavior and ionic conductivity) are influenced by the composition of the acid-base system and show asymmetry between acid dominant versus base dominant compositions. Here, we find that the electric double layer capacitance can be significantly improved by using protic ionic liquids compared to its aprotic counterpart through optimization of the mixture composition (i.e., the ratio of acid to base). We demonstrate the influence of pore size and applied voltage on the capacitance performance of protic ionic liquids and provide insight into microscopic understanding of ion and solvent distributions inside micropores.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗