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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Progress Report on the Investigation of Separable Floating Layers in Hanford Double-Shell Tank Supernates

A review of studies performed the last four years at 222-S Laboratory on separable floating solids including demonstration of the formation of a floating layer in the organic-bound simulated solids and investigation of floating solids found in AN-101 and AW-104 as well as carbonate precipitation floating on the surface of AN-107 grab samples. Demonstrated that semivolatile organic analysis can detect separable organics including tributyl phosphate, degradation products of Quintolubric hydraulic fluid, and hydrocarbon as tentatively identified compounds. In addition, an evaluation of the relationship of small organic acids to the total organic carbon is discussed in selected double-shell tank supernate. A systematic approach is presented to monitor separable organics and insoluble particulates in the double-shell tank waste.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Super Charge Separation and High Voltage Phase in Na x MnO 2

Na x MnO 2 shows Mn 3+ and Mn 4+ charge separation with the charge stripe ordering upon Na deintercalation at x = 5/8. In this paper it is shown that, surprisingly, at lower Na compositions of 5/8 > x ≥ 1/18 the phase evolution pathway of Na x MnO 2 upon Na deintercalation shows a unique phenomenon of super charge separation, where the Mn 3+ and Mn 4+ ions fully charge-separate into charge superplanes formed by succession of charge stripes in the third dimension. Furthermore, the Mn 3+ superplanes attract Na ions electronically, and dominate the antiferromagnetic interactions in NaMnO 2 . Na ions in Mn 3+ superplanes also naturally pillar the MnO 2 layers to form the unusual O1 phases with large interlayer distances at x < 1/3, which dominates the unique electrochemical behavior of NaMnO 2 .

25 ENERGY STORAGE↗
DOE OSTI2020

Synthesis of Ionic Ultramicroporous Polymers for Selective Separation of Acetylene from Ethylene

The design of highly stable and efficient porous materials is essential for developing breakthrough hydrocarbon separation methods based on physisorption to replace currently used energy-intensive distillation/absorption technologies. Efforts to develop advanced porous materials such as zeolites, coordination frameworks, and organic polymers have met with limited success. Here, a new class of ionic ultramicroporous polymers (IUPs) with high-density inorganic anions and narrowly distributed ultramicroporosity is reported, which are synthesized by a facile free-radical polymerization using branched and amphiphilic ionic compounds as reactive monomers. A covalent and ionic dual-crosslinking strategy is proposed to manipulate the pore structure of amorphous polymers at the ultramicroporous scale. The IUPs exhibit exceptional selectivity (286.1–474.4) for separating acetylene from ethylene along with high thermal and water stability, collaboratively demonstrated by gas adsorption isotherms and experimental breakthrough curves. Modeling studies unveil the specific binding sites for acetylene capture as well as the interconnected ultramicroporosity for size sieving. Finally, the porosity-engineering protocol used in this work can also be extended to the design of other ultramicroporous materials for the challenging separation of other key gas constituents.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Highly Permeable Oligo(ethylene oxide)- co -poly(dimethylsiloxane) Membranes for Carbon Dioxide Separation

Here, a series of cross–linked, freestanding oligo(ethylene oxide)– co –(polydimethylsiloxane–norbornene) membranes with varied composition is synthesized via in situ ring–opening metathesis polymerization. These membranes show remarkably high CO 2 permeabilities (3400 Barrer) and their separation performance approaches the Robeson upper bound. The excellent permeability of these copolymer membranes provides great potential for real–world applications where enormous volumes of gases must be separated. The gas transport properties of these films are found to be directly proportional to oligo(ethylene oxide) content incorporation, which stems from the increased solubility selectivity change within the copolymer matrix. This work provides a systematic study of how gas separation performance in rubbery membranes can be enhanced by tuning the CO 2 –philicity of their constituent monomeric subunits.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Stretchable Lithium-Ion Batteries Enabled by Device-Scaled Wavy Structure and Elastic-Sticky Separator

Fast developments and substantial achievements have been shaping the field of wearable electronic devices, resulting in the persistent requirement for stretchable lithium-ion batteries (LIBs). Despite recent progress in stretchable electrodes, stretching full batteries, including electrodes, separator, and sealing material, remains a great challenge. Here, a simple design concept for stretchable LIBs via a wavy structure at the full battery device scale is reported. All components including the package are capable of being reversibly stretched by folding the entire pouch cell into a wavy shape with polydimethylsiloxane filled in each valley region. In addition, the stretchable, sticky, and porous polyurethane/poly(vinylidene fluoride) membrane is adopted as a separator for the first time, which can maintain intimate contact between electrodes and separator to continuously secure ion pathway under dynamic state. Commercial cathode, anode, and package can be utilized in this rationally designed wavy battery to enable stretchability. The results indicate good electrochemical performances and long-term stability at repeatable release–stretch cycles. A high areal capacity of 3.6 mA h cm -2 and energy density of up to 172 W h L -1 can be achieved for the wavy battery. The promising results of the cost-effective wavy battery with high stretchability shed light on the development of stretchable energy storages.

25 ENERGY STORAGE↗
DOE OSTI2023

Modulating the Mixing Gibbs Free Energy to Enhance Solid–Liquid Phase Separation for High–Performance Organic Solar Cells

Organic solar cells (OSC) feature a hierarchical structure with the electron donor/acceptor layer sandwiched by anode and cathode, which raises the importance of controlling the molecular crystal orientation, domain size, and vertical distribution to facilitate the charge collection at electrodes. However, the similar conjugated backbone of donor/acceptor material and fast film–formation kinetics have led to spinodal–decomposition–orientated phase separation that result in the film presenting an intimately mixed morphology and random molecular orientation. To solve the issue, the mixing Gibbs free energy–triggered solid–liquid phase separation during the film formation process is enhanced by solidifying one component and solvating the other based on a liquid additive. Following the liquid evaporation process, a favorable vertical distribution is obtained. Meanwhile, the prolonged solvation process enlarges the domain size and assists the molecules to diffuse and orient properly, enabling better exciton/charge dynamics during the power conversion processes. As a result, the fabricated devices exhibit a fill factor over 80% and an efficiency of 18.72%, which is one of the top efficiencies for binary OSCs. In conclusion, insights and a methodology is provided here to manipulate the organic donor/acceptor phase separation in terms of mixing Gibbs free energy.

14 SOLAR ENERGY↗
DOE OSTI2020

Modeling and simulation of gas separations with spiral–wound membranes

Models for gas separations with spiral–wound membranes are developed and found to exhibit good agreement with experiments performed on N 2 /O 2 mixtures. The two–dimensional (2D) model can be accurately approximated by a one–dimensional (1D) surrogate model when the spacer widths are chosen to make the channel pressure drops small. Subsequently, the separation of propane/propylene mixtures from the recycle purge stream of a polypropylene reactor is investigated. Assuming ideal gas is found to lead to significant overestimations in membrane stage cuts (sometimes more than 10%), an extent comparable to that associated with extrapolating constant olefin permeance from a low–pressure condition. While olefin permeance can change significantly with pressure, using a constant–permeance formulation can result in a small (< 2.5%) underprediction in stage cut if the value for the permeance is taken from the feed condition. Finally, membrane properties and costs necessary for a viable separation process are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Accelerating Membrane-based CO 2 Separation by Soluble Nanoporous Polymer Networks Produced by Mechanochemical Oxidative Coupling

Achieving homogeneous dispersion of nanoporous fillers within membrane architectures remains a great challenge for mixed-matrix membrane (MMMs) technology. Imparting solution processability of nanoporous materials would help advance the development of MMMs for membrane-based gas separations. A mechanochemically assisted oxidative coupling polymerization strategy was used to create a new family of soluble nanoporous polymer networks. The solid-state ball-milling method affords inherent molecular weight control over polymer growth and therefore provides unexpected solubility for the resulting nanoporous frameworks. MMM-based CO 2 /CH 4 separation performance was significantly accelerated by these new soluble fillers. In conclusion, we anticipate this facile method will facilitate new possibilities for the rational design and synthesis of soluble nanoporous polymer networks and promote their applications in membrane-based gas separations.

36 MATERIALS SCIENCE↗
DOE OSTI2023

ATRP Enhances Structural Correlations In Polymerization–Induced Phase Separation**

Synthetic methods to control the structure of materials at sub–micron scales are typically based on the self–assembly of structural building blocks with precise size and morphology. On the other hand, many living systems can generate structure across a broad range of length scales in one step directly from macromolecules, using phase separation. Here, we introduce and control structure at the nano– and microscales through polymerization in the solid state, which has the unusual capability of both triggering and arresting phase separation. In particular, we show that atom transfer radical polymerization (ATRP) enables control of nucleation, growth, and stabilization of phase–separated poly–methylmethacrylate (PMMA) domains in a solid polystyrene (PS) matrix. ATRP yields durable nanostructures with low size dispersity and high degrees of structural correlations. Furthermore, we demonstrate that the length scale of these materials is controlled by the synthesis parameters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Nonnegative tensor decomposition with custom clustering for microphase separation of block copolymers

High–dimensional datasets are becoming ubiquitous in many applications and therefore unsupervised tensor methods to interrogate them are needed. Here, we report a new unsupervised machine learning (ML) approach (NTFk) based on nonnegative tensor factorization integrated with a custom k–means clustering. We demonstrate the ability of NTFk to extracting temporal and spatial features of phase separation of copolymers as they are modeled by self–consistent field theory. Microphase separation of block copolymers has been extensively studied both experimentally and theoretically. However, the interpretation of computer simulations and/or experimental data, representing temporal and spatial changes of molecular species concentration is still a challenging task. Thus, extracting the phase diagram from simulations or experimental data as well as the interpretation of data requires discernment of the model/experimental parameters (such as, temperature, concentrations, the number of molecular species and the interaction between species) impact on the microphase separation process. An attractive and unique aspect of the introduced ML method is that it ensures the nonnegativity of the extracted latent features. Nonnegativity is an essential constraint needed to obtain interpretable and sparse latent features that are parts–based representation of the data. The custom clustering in NTFk serves to estimate the number of latent features in the data.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2023

Multi–Modular Design of Stable Pore–Space–Partitioned Metal–Organic Frameworks for Gas Separation Applications

Pore space partition (PSP) is an effective materials design method for developing high-performance small-pore materials for storage and separation of gas molecules. The continued success of PSP depends on broad availability and judicious choice of pore-partition ligands and better understanding of each structural module on stability and sorption properties. Here, by using substructural bioisosteric strategy (sub-BIS), a dramatic expansion of pore-partitioned materials is targeted by using ditopic dipyridyl ligands with non-aromatic cores or extenders, as well as by expanding heterometallic clusters to uncommon nickel–vanadium and nickel–indium clusters rarely known before in porous materials. The dual-module iterative refinement of pore-partition ligands and trimers leads to remarkable enhancement of chemical stability and porosity. Here a family of 23 pore-partitioned materials synthesized from five pore-partition ligands and seven types of trimeric clusters is reported. New materials with such compositionally and structurally diverse framework modules reveal key factors that dictate stability, porosity, and gas separation properties. Among these, materials based on heterometallic vanadium–nickel trimeric clusters give rise to the highest long-term hydrolytic stability and remarkable uptake capacity for CO 2 , C 2 H 2 /C 2 H 4 /C 2 H 6 , and C 3 H 6 /C 3 H 8 hydrocarbon gases. Here, the breakthrough experiment shows the potential application of new materials for separating gas mixtures such as C 2 H 2 /CO 2 .

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

Coupling of nitric acid digestion and anion-exchange resin separation for the determination of methylmercury isotopic composition within organisms

Isotope ratios of methylmercury (MeHg) within organisms can be used to identify sources of MeHg that have accumulated in food webs, but these isotopic compositions are masked in organisms at lower trophic levels by the presence of inorganic mercury (iHg). To facilitate measurement of MeHg isotope ratios in organisms, we developed a method of extracting and isolating MeHg from fsh and aquatic invertebrates for compound-specifc isotopic analysis involving nitric acid digestion, batch anion-exchange resin separation, and pre-concentration by purge and trap. Recovery of MeHg was quantifed after each step in the procedure, and the average cumulative recovery of MeHg was 93.4±2.9% (1 SD, n=28) for biological reference materials and natural biota samples and 96.9±1.8% (1 SD, n=5) for aqueous MeHgCl standards. The amount of iHg impurities was also quantifed after each step, and the average MeHg purity was 97.8±4.3% (1 SD, n=28) across all reference materials and natural biota samples after the fnal separation step. Measured MeHg isotopic compositions of reference materials agreed with literature values obtained using other MeHg separation techniques, and MeHg isotope ratios of aqueous standards, reference materials, and natural biota samples were reproducible. On average, the reproducibility associated with reference material process replicates (2 SD) was 0.10‰ for δ 202 MeHg and 0.04‰ for Δ 199 MeHg. This new method provides a streamlined, reliable technique that utilizes a single sample aliquot for MeHg concentration and isotopic analysis. Furthermore, this promotes a tight coupling between MeHg concentration, %MeHg, and Hg isotopic composition, which may be especially benefcial for studying complex food webs with multiple isotopically distinct sources of iHg and/or MeHg.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Evaluation of SR/ TEVA/ TRU triple stack for separation of activation products

A rapid method to separate Ta, Po, Au, Pt, and W from a sample containing mixed fission and activation products was developed using three commercially available extraction chromatography resins stacked in series. When the separation was tested using all the target activation products, even those with short half-lives were measurable. Finally, combining multiple extraction chromatography resin cartridges in tandem allows for multiple short-lived activation products to be separated from one sample addition without the complication of multiple steps.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2019

Enhanced Separation of Sm and La from Sm{sub 2}O{sub 3}-La{sub 2}O{sub 3} Mixtures Based on a Reduction–Oxidation Method

The Sm{sub 2}O{sub 3}-La{sub 2}O{sub 3} mixture was converted to the component chlorides, and Sm and La were separated from the chlorides using the reduction–oxidation method based on the chemical valence variation of Sm. In the reduction stage, samarium (III) chloride was reduced to samarium (II) chloride using hydrogen. In the oxidation stage, samarium (II) chloride was oxidized by water to SmCl{sub 3} and water-insoluble SmOCl. After filter separation of SmOCl, the Sm{sub 2}O{sub 3} content in the initial La{sub 2}O{sub 3}-Sm{sub 2}O{sub 3} mixture was reduced by ~ 50 pct. These results demonstrate an innovative method for pyrometallurgical separation of Sm and La from Sm{sub 2}O{sub 3}-La{sub 2}O{sub 3} mixtures.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Experiments with a prototype titanium hot cavity surface ionization source intended for electromagnetic separation of radioactive samarium and other lanthanide elements

This paper reports experimental results of a prototype titanium surface ionization source. For the first time, a lanthanide ion beam has been produced with a surface ionizer composed completely of titanium metal. Titanium does not readily activate with neutron irradiation. This offers the potential for inserting an ion source made of titanium directly into a reactor with a pre-loaded non-radioactive lanthanide target. This seamlessly integrates target irradiation with isotope separation, eliminating post irradiation sample manipulation. Samarium ion beam currents up to 960 nA have been produced in an off-line test bench equipped with rudimentary beam optics. This is a crucial step toward the development of an ionization source adopted for the electromagnetic isotope separator (EMIS) facility, which has been designed for high throughput separations of radioactive 153 Sm and other lanthanides of interest in the field of nuclear medicine. The ion current and important factors affecting the performance of the ion source, such as the ionizer temperature and thermal gradient, are discussed. Lastly, the experimental results are presented together with a discussion of future modifications to optimize the overall surface ionization source performance.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2021

Chemical looping air separation with Sr 0.8 Ca0.2Fe 0.9 Co 0.1 O 3-δ perovskite sorbent: Packed bed modeling, verification, and optimization

Chemical looping air separation (CLAS) represents a promising approach for efficient O 2 production from the air. This present study aims at optimizing the absorber/desorber operations and the separation process with extensive experimental validation. Specifically, a one-dimensional packed bed model was developed to investigate the CLAS operation with a Sr 0.8 Ca 0.2 Fe 0.9 Co 0.1 O 3-δ perovskite sorbent. The redox thermodynamics of perovskite sorbent was measured by TGA and then incorporated into a linear driving force model to describe the O 2 absorption and desorption rates. Both 4-step and 5-step air separation cycle configurations, with various cyclic structures, were performed in a subpilot-scale packed bed. The model predicted O2 purity and productivity were consistent with experimental results, supporting its accuracy and applicability. Parametric analysis and multi-objective optimization were further carried out to assess the performance of CLAS. Both O 2 purity and recovery increased monotonically with the cycle time, airflow rate, steam flow rate, and absorption pressure. Meanwhile, optimal O 2 productivity and power consumption can only be achieved by specific combinations of these parameters. The optimized results showed that CLAS can be highly competitive when compared to conventional pressure swing adsorption (PSA) or cryogenic distillation. The 5-step cycle configuration achieved a minimum power consumption of 118 kW·h for producing 1 ton O 2 with ≥ 95% purity. The maximum O 2 productivity reached 0.0932 g O2 /(g sorbent ·h) with 390 kW·h/ton O 2 of energy consumption (95% pure). The optimization results also indicate that CLAS can potentially be more efficient than cryogenic distillation even when the required O 2 purity is above 99%.

42 ENGINEERING↗
DOE OSTI2022

Generalized optimization-based synthesis of membrane systems for multicomponent gas mixture separation

Synthesizing a membrane system to separate multicomponent gas mixture is challenging due to the combinatorial number of feasible configurations and the difficulties in describing the multicomponent permeators. Here we present a mixed-integer nonlinear programming (MINLP) model for synthesizing membrane systems for multicomponent gas mixture separation. The approach employs a richly connected superstructure to represent numerous potential system configurations, and different physics-based surrogate permeator models, such as countercurrent flow or crossflow, to be used in each stage. Moreover, to describe realistic systems, pressure drop equations can be included. We also present solution methods to accelerate the solution process. Through a case study of natural gas sweetening, we demonstrate that the proposed approach is able to obtain good solutions using an off-the-shelf global optimization solver. Finally, we expand the conventional membrane system synthesis problem by introducing feed variability in our model through a case study of an integrated reactor-separation system.

42 ENGINEERING↗
DOE OSTI2021

Breaking the trade-off between selectivity and adsorption capacity for gas separation

It is generally recognized that porous solids (sorbents) with high selectivity and high adsorption capacity offer potential for energy-efficient gas separations. Unfortunately, there is generally a trade-off between capacity and selectivity, which represents a roadblock to the utility of sorbents in key industrial processes. For example, acetylene (C 2 H 2 ), an important fuel and chemical intermediate, is produced with CO 2 as an impurity, and the similar physicochemical properties of C 2 H 2 and CO 2 mean that most sorbents are poorly selective. Hybrid ultramicroporous materials (HUMs) are candidates for gas separations as they exhibit benchmark selectivity for several key gas pairs. Unfortunately, existing HUMs are handicapped by low capacity. Here, we report a new HUM, SIFSIX-21-Ni, that addresses the trade-off between selectivity and capacity that has plagued sorbents, as its high uptake and high selectivity renders it the new benchmark for C 2 H 2 /CO 2 separation performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗