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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 577 records · Page 32
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Joining, Disassembly, and Reconfiguration of Thermoplastic Composites for Space Applications

Thermoplastic composites are increasingly being investigated for aerospace applications because of their relatively short processing time, good chemical and radiation resistance, and potential for reforming and reuse via melting. The manufacturing, reforming, and reuse of thermoplastic composites can be leveraged to advance joining, disassembly, and reassembly of structures for space exploration activities. Potential applications include, but are not limited to, habitats and on-orbit assembly and reassembly of large-scale truss structures. This work focuses on demonstrating the feasibility of joining, disassembly, and reassembly of a thermoplastic bond using heat and pressure. Polyether ether ketone (PEEK) composite adherends were joined using low-melt polyaryl ether ketone (LM-PAEK) thermoplastic films at the bonding interface. The single lap shear specimens with LM-PAEK film were tested and had a maximum shear strength between 5 and 8 MPa and consistently failed adhesively at the bondline. Reassembly of disassembled specimens was successfully demonstrated using additional thermoplastic interlayers. Thus, the reassembly of thermoplastic composite joints was found to be feasible. However, additional work is required to reduce film flowout and optimize consolidation parameters for an in space environment.

thermoplastic composites↗
DOE OSTI2020

Conversion, Stability, and Selectivity Improvements Through Catalyst Development for the Reductive Etherification Reaction

Economical pathways from lignocellulosic non-food biomass feedstocks to biofuels with appropriate fuel properties are necessary for displacing fossil-fuel derived diesel use in medium-/heavy duty vehicles. Oxygenated compounds have recently shown promise due to low sooting tendencies and autoignition properties and molecules with sufficiently high carbon numbers can meet the requisite standards for water solubility and flash point. Coupling waste biomass derived small molecules into bioblendstock targets through the reductive etherification reaction shows potential for increasing molecular weight without losing the advantages of oxygenates. However, the transition to industrial viability for this process is limited by strong catalyst deactivation in typical flow reactor systems. Strong acid resins such as Amberlyst-15 (A-15) show excellent activity in batch reactions but are limited to low temperatures and are poisoned by the side-product, water. In this talk, I will describe our recent work in catalyst synthesis and testing to select superior options with improved aqueous and thermal stability in reductive etherification flow reactions. Water-tolerant solid acid catalysts have potential to improve the conversion and selectivity to the ether target at temperatures above the degradation point of A-15. Analysis techniques such as physisorption, chemisorption, x-ray diffraction and transmission electron microscopy are being used to characterize the active sites. These techniques are also being used to evaluate degradation of the catalyst after extensive flow reactions in addition to comparative efficiency testing with standardized cyclohexene hydrogenation reactions. Finally, I will discuss a demonstration of the full pathway from bio-derived butyric acid to the performance-advantaged ether product and the additional obstacles from side-products and purification limitations in the preliminary upgrading reactions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2020

Lithium-sulfur battery with lithium polysulfide catholyte

A liquid catholyte for a Li-S battery comprises a non-aqueous solution of at least one lithium polysulfide of formula Li 2 S x (wherein x is selected from 4, 6, and 8) and an anion receptor compound capable of complexing with polysulfide anion. The non-aqueous solution typically is composed of the Li 2 S x and the anion receptor compound dissolved in a non-aqueous solvent (e.g., one or more organic ether or fluorinated ether solvents). The anion receptor compound typically is present in the catholyte at a concentration of about 0.1 M to about 4 M. Li-S batteries comprise a metallic lithium anode; a porous conductive substrate; a separator membrane between the anode and the porous conductive substrate; and the liquid catholyte composition within pores of the substrate.

25 ENERGY STORAGE↗
DOE OSTI2020

Electrolyte salts for rechargeable magnesium-ion batteries

Magnesium salts suitable for use in an electrolyte for a magnesium ion electrochemical cell are described herein. The salts are magnesium tetra(perfluoroalkoxy)metalates, optionally solvated with up to seven ether molecules coordinated to the magnesium ion thereof. In one embodiment, the salt has the empirical formula: Mg(Z) n 2+ [M(OCR 3 ) 4 − ] 2 (Formula (I)) wherein Z is an ether; n is 0 to about 7; M is Al or B; and each R independently is a perfluoroalkyl group (e.g., C 1 to C 10 perfluoroalkyl). The magnesium salts of Formula (I) are suitable for use as electrolyte salts for magnesium ion batteries (e.g., 5 V class magnesium batteries) and exhibit a wide redox window that is particularly compatible with magnesium anode. The salts are relatively cost effective to prepare by methods described herein, which are conveniently scalable to levels suitable for commercial production.

Lau, Ka-Cheong↗
DOE OSTI2022

Phosphorus-containing solid catalysts and reactions catalyzed thereby, including synthesis of p-xylene

Methods and phosphorus-containing solid catalysts for catalyzing dehydration of cyclic ethers (e.g., furans, such as 2,5-dimethylfuran) and alcohols (e.g., ethanol and isopropanol). The alcohols and cyclic ethers may be derived from biomass. One example includes a tandem Diels-Alder cycloaddition and dehydration of biomass-derived 2,5-dimethyl-furan and ethylene to renewable p-xylene. The phosphorus-containing solid catalysts are also active and selective for dehydration of alcohols to alkenes.

Cho, Hong Je↗
DOE OSTI2023

Catalytic cathode for a lithium-oxygen battery

A metal-air battery includes an anode; a low-dimensional catalyst cathode; and an electrolyte; wherein: the low-dimensional catalyst cathode comprises a functional metal layer on a carbon support overcoated with a catalyst layer; the electrolyte comprises an aprotic solvent that is an ether-based solvent, a fluorinated ether-based solvent, an oligo (ethylene oxide) solvent, or a mixture of any two or more thereof; and the electrolyte is free of carbonate solvents.

25 ENERGY STORAGE↗
DOE OSTI2023

Proton exchange membrane material and methods of making the same

Hydrocarbon proton exchange membranes are disclosed that are composed of a material including a hydrophobic main chain, and acidic side chains. The main chain includes a polyaryl structure that is substantially free of ether linkages and also includes a fluoromethyl substituted carbon. The acidic side chains include a hydrocarbon tether terminated by a strongly acidic group, such as a fluoroalkyl sulfonate group. Chemical stability of the material is increased by removing the ether linkages from the main chain. The hydrophobic main chain and substantially hydrophilic side chains create a phase-separated morphology that affords enhanced transport of protons and water across the membrane even at low relative humidity levels. These materials are advantageous as membranes for use in fuel cells, redox flow batteries, water hydrolysis systems, sensors, electrochemical hydrogen compressors, actuators, water purifiers, gas separators, etc.

Bae, Chulsung↗
DOE OSTI2023

Electrolytes for lithium batteries with carbon and/or silicon anodes

Electrolytes for lithium ion batteries with carbon-based, silicon-based, or carbon- and silicon-based anodes include a lithium salt; a nonaqueous solvent comprising at least one of the following components: (i) an ester, (ii) a sulfur-containing solvent, (iii) a phosphorus-containing solvent, (iv) an ether, (v) a nitrile, or any combination thereof, wherein the lithium salt is soluble in the solvent; a diluent comprising a fluoroalkyl ether, a fluorinated orthoformate, a fluorinated carbonate, a fluorinated borate, or a combination thereof, wherein the lithium salt has a solubility in the diluent at least 10 times less than a solubility of the lithium salt in the solvent; and an additive having a different composition than the lithium salt, a different composition than the solvent, and a different composition than the diluent.

Xu, Wu↗
DOE OSTI2023

Aromatic Monomer Production from Lignin Through Catalytic Carbon-Carbon Bond Cleavage

The conversion of lignin, the heterogeneous aromatic polymer found in terrestrial plant cell walls, into renewable bio-derived chemicals is critical to enable a viable lignocellulose-based bioeconomy. While lignin finds some limited industrial uses today, cost-effective and robust processes for the depolymerization of lignin to aromatic monomers would substantially expand lignin applications to larger markets, such as sustainable polymers and commodity chemicals. Historically, catalytic lignin depolymerization has focused on aryl-ether bond cleavage. A large fraction of aromatics in lignin, however, is linked by various recalcitrant carbon-carbon (C-C) bonds, which present a challenging substrate for depolymerization to aromatic monomers at high yields. To increase monomer yields above those accessible through aryl-ether bond cleavage alone, here we report that autoxidation catalysis cleaves C-C bonds in various lignin substrates with high atom economy. The catalyzed autoxidations of phenol-protected reductive catalytic fractionation (RCF) oil oligomers and hydrodeoxygenation (HDO) oil are described. The stream oxygenated monomers produced from the various lignin substrates are bioavailable as demonstrated by their bioconversion to cis,cis-muconate by engineered strains of Pseudonomas putida.

autoxidation↗
DOE OSTI2023

Electrolytes for lithium-ion batteries operating at extreme conditions

Electrolytes for lithium ion batteries with carbon-based, silicon-based, or carbon- and silicon-based anodes include a lithium salt; a nonaqueous solvent comprising at least one of the following components: (i) an ester, (ii) a sulfur-containing solvent, (iii) a phosphorus-containing solvent, (iv) an ether, (v) a nitrile, or any combination thereof, wherein the lithium salt is soluble in the solvent; a diluent comprising a fluoroalkyl ether, a fluorinated orthoformate, a fluorinated carbonate, a fluorinated borate, a fluorinated phosphate, a fluorinated phosphite, or any combination thereof, wherein the lithium salt has a solubility in the diluent at least 10 times less than a solubility of the lithium salt in the solvent; and an additive having a different composition than the lithium salt, a different composition than the solvent, and a different composition than the diluent. In some electrolytes, the nonaqueous solvent comprises an ester.

Cao, Xia↗
DOE OSTI2022

Selective Removal of Barium and Hardness Ions from Brackish Water with Chemically Enhanced Electrodialysis

The use of a nonconventional water resource for energy and industrial applications often requires extraction of low-level undesirable ions from matrices of benign dominant ions. In this study, the selective extraction of Ba 2+ and Mg 2+ from synthetic brine solutions was evaluated using strong acid cation-exchange membranes modified with the surface deposition of macrocyclic molecules including crown ethers and calixarenes. Compared to the bare membrane, vinylbenzo-18-crown-6 (VB18C6) and calix[4]arene-amended membranes showed increased selectivity for Ba 2+ and Mg 2+ with respect to the dominant ion (Na + ) by up to fourfolds, with the calix[4]arene-modified membrane achieving more selective separation than VB18C6. Optimal selectivity was achieved at a moderate-to-high current density (3.1–6.3 mA/cm 2 ), which was attributed to the alleviation of transport limitation in the boundary layer by the surface modification. Amendment of a calix[4]arene derivative with a crown-6 “boot strap” and two carboxylic groups resulted in reduced selectivity due to the formation of strong complexes with divalent ions. Furthermore, these results show that surface deposition of ion sequestrants can be a versatile approach to improve the membrane’s selectivity; however, the performance is sensitive to feed water salinity, current loading, and the macrocycle-ion chemistry, where there is a trade-off between ion affinity and mobility.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Nanofiltration Membranes for Li + /Mg 2+ Separation: Materials and Mechanisms

Nanofiltration (NF) membranes have garnered significant interest for Li + /Mg 2+ separation, a crucial step in lithium extraction from brines. The state-of-the-art commercial LiNE-XD membrane exhibits a Li + /Mg 2+ separation factor (SF Li/Mg ) of 42 at pH 3.3, due to the positive charges on the membrane surface and its strong size-sieving ability. Membranes with higher separation factors at a broad pH range are being pursued to improve separation efficiency. This work aims to provide a timely and comprehensive assessment of advanced NF membranes with superior Li + /Mg 2+ separation properties, as well as their structure and property relationships for designing next-generation membranes. We describe transport mechanisms for ions in NF membranes and discuss governing parameters and models employed to quantify the Li + /Mg 2+ separation. High-performance membrane materials are exhaustively introduced, including commercial and modified polyamides, two-dimensional materials, metal–organic frameworks, crown ethers, and their blends. Finally, we critically compare these membranes in an upper bound plot and highlight the opportunities and challenges of NF membranes for practical Li + /Mg 2+ separations.

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

Neutron Insights into Sorption Enhanced Methanol Catalysis

Sorption enhanced methanol production makes use of the equilibrium shift of the CO 2 hydrogenation reaction towards the desired products. However, the increased complexity of the catalyst system leads to additional reactions and thus side products such as dimethyl ether, and complicates the analysis of the reaction mechanism. On the other hand, the unusually high concentration of intermediates and products in the sorbent facilitates the use of inelastic neutron scattering (INS) spectroscopy. Despite being a post-mortem method, the INS data revealed the change of the reaction path during sorption catalysis. Concretely, the experiments indicate that the varying water partial pressure due to the adsorption saturation of the zeolite sorbent influences the progress of the reaction steps in which water is involved. Experiments with model catalysts support the INS findings.

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

Spectroscopic insight into carbon speciation and removal on a Cu/BEA catalyst during renewable high-octane hydrocarbon synthesis

Conversion of methanol and dimethyl ether (DME) to high-octane gasoline catalyzed by beta zeolite (BEA) provides an opportunity for the production of high-quality fuels from renewable carbon sources (e.g., gasified biomass). Recent research demonstrated that a Cu-modified BEA zeolite catalyst (Cu/BEA) offered advantages over the unmodified BEA catalyst due to multifunctional Cu species that enabled incorporation of co-fed H2, reactivation of light alkanes, and reduction of products from the aromatic hydrocarbon pool. The shift in hydrocarbon pool chemistry has the potential to influence the identity and relative composition of surface carbon species that are often linked to deactivation. A detailed understanding of these carbon species is important to develop an effective and efficient regeneration procedure that can enable the transition from fundamental catalyst development to commercial application. Here, we applied complementary ex situ and in situ characterization techniques to compare the structures of surface carbon species on post-reaction Cu/BEA and unmodified BEA catalysts. Both catalysts contained acyclic and aromatic hydrocarbons along with graphitic carbon species. However, the post-reaction Cu/BEA catalyst had a lower polycyclic aromatic content, and further, the graphitic species were more hydrogenated and defective. It was also found that the presence of Cu promoted carbon removal at lower temperatures than for unmodified BEA through activation of O2 by Cu oxide during thermal oxidation. The fundamental insight into the composition of surface carbon species enabled the design of an effective and efficient regeneration strategy for the DME homologation reaction over Cu/BEA, resulting in full recovery of the catalyst activity.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2026

Effect of H 2 O on the ethylene glycol/alkali dismantling of bagasse for high-value conversion

Using a high-boiling alcohol system to dismantle main components of biomass is a feasible technology. Reducing dismantle operating costs and improving dismantle efficiency are essential for promoting the green, economical, and sustainable development of biomass refining. Therefore, based on the low cost and chemical properties of H 2 O at high temperature, the effects of different H 2 O dosages in NaOH-catalyzed ethylene glycol (HBAA) system on the dismantling efficiency of bagasse, surface lignin coverage, recovered-lignin activity and enzymatic hydrolysis efficiency were investigated. Compared with the HBAA dismantling system without H 2 O, the HBAA system with 60% w/v H 2 O can obviously increase the removal rates of lignin and hemicellulose, while recovering up to 99% of cellulose and significantly declining surface lignin coverage, thus enhancing the enzymatic hydrolysis efficiency. Additionally, the results of density functional theory calculations and 2D HSQC NMR analysis prove that the synergy between H 2 O and ethylene glycol can promote the esterification reaction occurrence at the α-C carbon cation in β-O-4 structure of lignin, thereby protecting the β-O-4 aromatic ether bond. Simultaneously, when the H 2 O dosage increase from 0% to 60%, the enzymatic yield increases from 84.51% to 93.74% with an enzyme load of 10 FPU/g. Based on experimental results, this study conducted a techno-economic analysis of bagasse dismantling for ethanol and co-production of lignin, achieving a minimum ethanol selling price of $\$$1.07 per kg. Here, in this study, a green and economical solution for dismantling the main components of bagasse is developed, which is important for the high-value conversion of bagasse.

Ethylene glycol↗
DOE OSTI2021

Effect of PCEs with different structures on hydration and properties of cementitious materials with low water-to-binder ratio

Polycarboxylate ethers (PCEs) with different structures and densities of anchor groups in the backbone were synthesized and characterized. The surface tension of their solutions, their adsorption on cementitious particles and zeta potential of cement-silica fume pastes with PCEs were measured. Their effects on hydration and properties of cement-silica fume paste with low water-to-binder ratio were examined. Results indicated that the adsorption kinetics of theses PCEs on cementitious particles are fitted the pseudo-second-order model. The introduction of long silane chain on PCE decreased its electrostatic adsorption, while PCE was adsorbed onto the surface of particles via both chemical and electrostatic adsorption, when silicon hydroxyl is directly connected to its backbone. In the presence of PCE with higher adsorbed amount, pastes exhibited lower yield stress and higher flowability, and higher strength at 7 d and 28 d. The low plastic viscosity, autogenous and drying shrinkage were related to the low surface tension of PCE solution.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Physical and chemical effects of isopropanol exchange in cement-based materials

Drying cement-based materials is a necessary step to characterize the microstructure by microscopy, adsorption, or mercury intrusion. The isopropanol (IPA) exchange method is commonly used to replace the pore solution prior to drying, as it reduces the capillary pressure and thereby helps to preserve the microstructure of the hydrated cementitious materials. However, some physical and chemical effects of IPA on hydration products have been reported. These effects cannot be completely avoided, but can be reduced by shortening the exchange duration, in particular for effects on ettringite. This study carried out experiments with different exchange durations and IPA removal techniques to address research gaps in the literature. For 1-mm cubes of cement paste with IPA diffusion coefficient of 1 × 10{sup −11} m{sup 2}/s, the compared exchange durations are 5 min, 15 min (value from the literature), 40 min (when the mixture at the sample center achieves 95% of the drop in surface tension from water to IPA), 80 min (when the IPA/water mixture at the sample center reaches an azeotrope), 5 h (when over 99% IPA is replaced at the sample center), and 24 h (prolonged exchange). After IPA exchange, samples were either directly dried at 40 °C with flushing N{sub 2} or washed by diethyl ether prior to N{sub 2} drying. Even though the exchange duration of 40 and 80 min, in theory, can reduce the damage from capillary pressure, the nitrogen adsorption results do not show any advantage in preventing microstructural alteration. The 5-h exchange provided results similar to the 24-h exchange, but the latter induced slightly more serious chemical effects resulting from the longer contact of IPA with hydration products. In addition, the compared IPA removal techniques do not show significant differences. Therefore, this study suggests using small samples (~1 mm) for microstructural studies following IPA exchange for a period corresponding to the time when 99% of the water (mole fraction) at the sample center is replaced.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Formulation of low clinker blended cements and concrete with enhanced fresh and hardened properties

Blended cements appear as the most promising way to massively produce cements with reduced environmental footprints. However, considering the generally lower early mechanical performance of highly blended cements, chemical admixtures are increasingly relied upon to increase early strength. However, in many cases this can negatively impact other properties as rheology and durability. This paper proposes an approach to formulate low clinker cements and concrete using moderate alkali activation or gypsum to enhance early and long-term compressive strength, without inducing excessive alkali-silica reaction (ASR) expansion. It examines blended cements containing burnt oil shale along with limestone and fly ash or slag as supplementary cementitious materials. It optimizes the combination of polycarboxylate ether (PCE) superplasticizers with the strength enhancers. Along with the use of Ca(NO{sub 3}){sub 2} to drive PCE adsorption, this provides good rheology control, increased early and long-term compressive strength, as well as acceptable ASR expansion in cements with only 50% clinker.

36 MATERIALS SCIENCE↗