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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Creation of Polymer Datasets with Targeted Backbones for Screening of High-Performance Membranes for Gas Separation

A simple approach was developed to computationally construct a polymer dataset by combining simplified molecular-input line-entry system (SMILES) strings of a targeted polymer backbone and a variety of molecular fragments. This method was used to create 14 polymer datasets by combining seven polymer backbones and molecules from two large molecular datasets (MOSES and QM9). Polymer backbones that were studied include four polydimethylsiloxane (PDMS) based backbones, poly(ethylene oxide) (PEO), poly(allyl glycidyl ether) (PAGE), and polyphosphazene (PPZ). The generated polymer datasets can be used for various cheminformatics tasks, including high-throughput screening for gas permeability and selectivity. This study utilized machine learning (ML) models to screen the polymers for CO2/CH4 and CO2/N2 gas separation using membranes. Several polymers of interest were identified. Here the results highlight that employing an ML model fitted to polymer selectivities leads to higher accuracy in predicting polymer selectivity compared to using the ratio of predicted permeabilities.

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

Regioisomeric Spirobifluorene CANAL Ladder Polymers and Their Gas Separation Performance

For this work, we synthesized and characterized two isomeric microporous hydrocarbon ladder polymers from catalytic arene norbornene annulation (CANAL) of regioisomeric bis-norbornene fused spirobifluorenes, where the ladder chains are connected either through the same fluorene unit or across two different fluorene units in spirobifluorene. This pair of isomeric polymers was used to investigate the effect of ladder macromolecular structures on the microporosity and transport properties. Both polymers form mechanically intact films with thermal stability up to 480 °C and relatively high BET surface areas. The polymer formed from 2,7-dibromospirobifluorene showed higher BET surface area and higher gas permeability than the polymer from 2,2'-dibromospirobifluorene despite similar intersegmental spacing as indicated by X-ray scattering. The aging behavior for both polymers followed the same trend as the previously reported CANAL-fluorene polymers, with dramatically increased permselectivities over time, resulting in gas separation performance above the 2008 upper bounds for H 2 /CH 4 and O 2 /N 2 .

36 MATERIALS SCIENCE↗
DOE OSTI2024

Method for electrochemical gas separation

A method for separating a Lewis acid gas from a fluid mixture, comprising contacting the fluid mixture with a reduced electroactive species; a non-aqueous electrolyte; and a stabilizing additive to form an anion adduct between the Lewis acid gas and the reduced electroactive species, wherein the electroactive species comprises an oxidized state, and at least one reduced state that bonds with the Lewis acid gas to form the anion adduct, wherein the stabilizing additive comprises a cationic Lewis acid, a hydrogen-bond donor, or a combination thereof, and the stabilizing additive is present in an effective amount to kinetically favor the forming of the anion adduct from the reduced electroactive species and thermodynamically favor the forming of the anion adduct in the thermodynamic equilibrium between the anion adduct and the reduced electroactive species.

Source record↗
DOE OSTI2024

Modification of ZIF‐8 Membranes for Gas Separation Using X‐ray Radiation

Here, we report an X-ray radiation-induced modification of the structure and gas permeation behavior of ZIF-8 membranes. With 300 min irradiation time, CO 2 permeance decreases by only 9 %, while N 2 and CH 4 permeances reduce by 75 and 65 %, respectively, leading to 3.7- and 2.6-fold enhancements in ideal selectivity for CO 2 /N 2 and CO 2 /CH 4 .

ZIF-8 membranes↗
DOE OSTI2024

Tailorable Multi–Modular Pore–Space–Partitioned Vanadium Metal–Organic Frameworks for Gas Separation

Currently, few porous vanadium metal-organic frameworks (V-MOFs) are known and even fewer are obtainable as single crystals, resulting in limited information on their structures and properties. Here this work demonstrates remarkable promise of V-MOFs by presenting an extensible family of V-MOFs with tailorable pore geometry and properties. The synthesis leverages inter-modular synergy on a tri-modular pore-partitioned platform. New V-MOFs show a broad range of structural features and sorption properties suitable for gas storage and separation applications for C 2 H 2 /CO 2 , C 2 H 6 /C 2 H 4 , and C 3 H 8 /C 3 H 6 . The c/a ratio of the hexagonal cell, a measure of pore shape, is tunable from 0.612 to 1.258. Other tunable properties include pore size from 5.0 to 10.9 Å and surface area from 820 to 2964 m 2 g –1 . With C 2 H 2 /CO 2 selectivity from 3.3 to 11 and high uptake capacity for C 2 H 2 from 65.2 to 182 cm 3 g –1 (298K, 1 bar), an efficient separation is confirmed by breakthrough experiments. The near-record high uptake for C 2 H 6 (166.8 cm 3 g –1 ) contributes to the promise for C 2 H 6 -selective separation of C 2 H 6 /C 2 H 4 . The multi-module pore expansion enables transition from C 3 H 6 -selective to more desirable C 3 H 8 -selective separation with extraordinarily high C 3 H 8 uptake (254.9 cm 3 g –1 ) and high separation potential (1.25 mmol g –1 ) for C 3 H 8 /C 3 H 6 (50:50 v/v) mixture.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Hyperthin Membranes for Gas Separations (Final Technical Report)

This final technical report summarizes DOE-supported research that we have carried out over the past 18 years; i.e., 09/01/2005-08/31/2023. Two hyperthin types of membranes that were reported most recently, which have practical potential for the separation of CO 2 from N 2 in flue are highlighted in this final technical report.

36 MATERIALS SCIENCE↗
DOE OSTI2024

2D Nitrogen‐Doped Graphene Materials for Noble Gas Separation

Abstract Noble gases, notably xenon, play a pivotal role in diverse high‐tech applications. However, manufacturing xenon is an inherently challenging task, due to its unique properties and trace abundance in the Earth's atmosphere. Consequently, there is a pressing need for the development of efficient methods for the separation of noble gases. Using mild fluorographene chemistry, nitrogen‐doped graphene (GNs) materials are synthesized with abundant aromatic regions and extensive nitrogen doping within the vacancies and holes of the aromatic lattice. Due to the organized interlayer “nanochannels”, nitrogen functional groups, and defects within the two‐dimensional (2D) structures, GNs exhibits effective selectivity for Xe over Kr at low pressure. This enhanced selectivity is attributed to the stronger binding affinity of Xe to GN compared to Kr. The adsorption is governed by London dispersion forces, as revealed by theoretical calculations using symmetry‐adapted perturbation theory (SAPT). Investigation of other GNs differing in nitrogen content, surface area, and pore sizes underscores the significance of nitrogen functional groups, defects, and interlayer nanochannels over the surface area in achieving superior selectivity. This work offers a new perspective on the design and fabrication of functionalized graphene derivatives, exhibiting superior noble gas storage and separation activity exploitable in gas production technologies.

Šedajová, Veronika↗
NASA NTRS1993

Pump Propels Liquid And Gas Separately

Design for pump that handles mixtures of liquid and gas efficiently. Containing only one rotor, pump is combination of centrifuge, pitot pump, and blower. Applications include turbomachinery in powerplants and superchargers in automobile engines. Efficiencies lower than those achieved in separate components. Nevertheless, design is practical and results in low consumption of power.

Harvey, Andrew↗
NASA NTRS1973

Evaluation of an electrochemical N2/H2 gas separator

A program was successfully completed to evaluate an electrochemical nitrogen/hydrogen (N2/H2) separator for use in a spacecraft nitrogen (N2) generator. Based on the technical data obtained a N2/H2 separator subsystem consisting of an organic polymer gas permeator first stage and an electrochemical second and third stage was estimated to have the lowest total spared equivalent weight, 257 kg (566 lb), for a 15 lb/day N2 generation rate. A pre-design analysis of the electrochemical N2/H2 separator revealed that its use as a first stage resulted in too high a power requirement to be competitive with the organic polymer membrane and the palladium-silver membrane separation methods. As a result, program emphasis was placed on evaluating the electrochemical. A parametric test program characterized cell performance and established second- and third-stage electrochemical N2/H2 separator operating conditions. A design verification test was completed on the second and third stages. The second stage was then successfully endurance tested for 200 hours.

Marshall, R. D.↗
DOE OSTI2021

Design and Gas Separation Performance of Imidazolium Poly(ILs) Containing Multivalent Imidazolium Fillers and Crosslinking Agents

This work introduces a series of vinyl-imidazolium-based polyelectrolyte composites, which were structurally modified via impregnation with multivalent imidazolium-benzene ionic liquids (ILs) or crosslinked with novel cationic crosslinkers which possess internal imidazolium cations and vinylimidazolium cations at the periphery. A set of eight [C4vim][Tf2N]-based membranes were prepared via UV-initiated free radical polymerization, including four composites containing di-, tri-, tetra-, and hexa-imidazolium benzene ILs and four crosslinked derivatives which utilized tri- and tetra- vinylimidazolium benzene crosslinking agents. Structural and functional characterizations were performed, and pure gas permeation data were collected to better understand the effects of “free” ILs dispersed in the polymeric matrix versus integrated ionic crosslinks on the transport behaviors of these thin films. These imidazolium PIL:IL composites exhibited moderately high CO2 permeabilities (~20–40 Barrer), a 4–7× increase relative to corresponding neat PIL, with excellent selectivities against N2 or CH4. The addition of imidazolium-benzene fillers with increased imidazolium content were shown to correspondingly enhance CO2 solubility (di- < tri- < tetra- < hexa-), with the [C4vim][Tf2N]: [Hexa(Im+)Benz ][Tf2N] composite showing the highest CO2 permeability (PCO2 = 38.4 Barrer), while maintaining modest selectivities (αCO2/CH4 = 20.2, αCO2/N2 = 23.6). Additionally, these metrics were similarly improved with the integration of more ionic content bonded to the polymeric matrix; increased PCO2 with increased wt% of the tri- and tetra-vinylimidazolium benzene crosslinking agent was observed. This study demonstrates the intriguing interactions and effects of ionic additives or crosslinkers within a PIL matrix, revealing the potential for the tuning of the properties and transport behaviors of ionic polymers using ionic liquid-inspired small molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Solvent–free Synthesis of Multi–Module Pore–Space–Partitioned Metal–Organic Frameworks for Gas Separation

Multi-module design of framework materials with multiple distinct building blocks has attracted much attention because such materials are more amenable to compositional and geometrical tuning and thus offer more opportunities for property optimization. Few examples are known that use environmentally friendly and cost-effective solvent-free method to synthesize such materials. Here, we report the use of solvent-free method (also modulator-free) to synthesize a series of multi-module MOFs with high stability and separation property for C 2 H 2 /CO 2 . The synthesis only requires simple mixing of reactants and short reaction time (2 h). Highly porous and stable materials can be made without any post-synthetic activation. Here, the success of solvent-free synthesis of multi-module MOFs reflects the synergy between different modules, resulting in stable pore-partitioned materials, despite the fact that other competitive crystallization pathways with simpler framework compositions also exist.

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

Rotational mechanical gas separator

The invention provides a system for removing target moieties from gas streams, the system comprising a supersonic expander coaxially positioned within an array of oblique shock inducers. Also provided is a method for removing target moieties from gas streams, the method comprising simultaneously subjecting the streams to supersonic expansion and oblique shock compression.

VanOsdol, John G.↗
DOE OSTI2022

Electrochemical process for gas separation

The present disclosure generally relates to apparatuses, systems, and methods for separating a target species (e.g., CO2) from a gas mixture (e.g., gas stream) via an electrochemical process.

Voskian, Sahag↗
DOE OSTI2023

Electrochemical process for gas separation

The present disclosure generally relates to apparatuses, systems, and methods for separating a target species (e.g., CO 2 ) from a gas mixture (e.g., gas stream) via an electrochemical process.

Voskian, Sahag↗
DOE OSTI2022

Hydrocarbon ladder polymers with ultrahigh permselectivity for membrane gas separations

Membranes have the potential to substantially reduce energy consumption of industrial chemical separations, but their implementation has been limited owing to a performance upper bound—the trade-off between permeability and selectivity. Although recent developments of highly permeable polymer membranes have advanced the upper bounds for various gas pairs, these polymers typically exhibit limited selectivity. We report a class of hydrocarbon ladder polymers that can achieve both high selectivity and high permeability in membrane separations for many industrially relevant gas mixtures. Additionally, their corresponding films exhibit desirable mechanical and thermal properties. Tuning of the ladder polymer backbone configuration was found to have a profound effect on separation performance and aging behavior.

Science & Technology - Other Topics↗
DOE OSTI2024

Above‐T g Annealing Benefits in Nanoparticle‐Stabilized Carbon Molecular Sieve Membrane Pyrolysis for Improved Gas Separation

Nanoparticles can suppress asymmetric precursor support collapse during pyrolysis to create carbon molecular sieve (CMS) membranes. This advance allows elimination of standard sol-gel support stabilization steps. Here we report a simple but surprisingly important thermal soaking step at 400 °C in the pyrolysis process to obtain high performance CMS membranes. The composite CMS membranes show CO 2 /CH 4 (50 : 50) mixed gas feed with an attractive CO 2 /CH 4 selectivity of 134.2 and CO 2 permeance of 71 GPU at 35 °C. Furthermore, a H 2 /CH 4 selectivity of 663 with H 2 permeance of 240 GPU was achieved for promising green energy resource-H 2 separation processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗