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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
NASA NTRS2014

Low Temperature Double-Layer Capacitors Using Asymmetric and Spiro-Type Quaternary Ammonium Salts

Double-layer capacitors capable of operating at extremely low temperatures (e.g., as low as -80.degree. C.) are disclosed. Electrolyte solutions combining a base solvent (e.g., acetonitrile) and a cosolvent are employed to lower the melting point of the base electrolyte. Example cosolvents include methyl formate, ethyl acetate, methyl acetate, propionitrile, butyronitrile, and 1,3-dioxolane. A quaternary ammonium salt including at least one of triethylmethylammonium tetrafluoroborate (TEMATFB) and spiro-(1,1')-bipyrrolidium tetrafluoroborate (SBPBF.sub.4), is used in an optimized concentration (e.g., 0.10 M to 0.75 M), dissolved into the electrolyte solution. Conventional device form factors and structural elements (e.g., porous carbon electrodes and a polyethylene separator) may be employed.

Brandon, Erik J.↗
DOE OSTI2021

Separations Consortium: Counter Current Chromatography

In support of the Bioenergy Technologies Office in recovering coproducts in biorefineries this project evaluates the use of Counter Current Chromatography (CCC) in recovering co-products from Reductive Catalytic Fractionation (RCF) oil, Alkaline Pretreatment Liquor (APL), aqueous phase Hydrothermal Liquefaction (HTL) oil, and Catalytic Fast Pyrolysis (CFP) oil. The project addresses three technology barriers in developing the bioeconomy; (1) Cost of production (2) Selective separation of organic acid species, and (3) Advanced bioprocess development. CCC is a unique, scalable, chromatographic technology that operates with two immiscible liquid phases moving counter current to one another. Unlike Simulated Moving Bed (SMB) technology, CCC is a true moving bed and because it uses liquids as both the stationary and mobile phase it can handle solids directly in the feed. This aspect of CCC allows it to skip the expensive filtration step needed prior to traditional SMB, furthermore the liquid phases are composed on relatively inexpensive organics (e.g. hexane and ethyl acetate). This project develops CCC methods for direct isolation of co-products from RCF oil, APL, HTL aqueous, and CFP oil. TechnoEconomic Analysis and process modeling is presented to compare CCC to SMB and assess its applicability in a holistic biorefinery. Initial results indicate approximately 4x reductions in solvent demand and 2x reduction in energy consumption compared to SMB.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Comparative Study on the Pretreatment of Aspen and Maple With 1-Ethyl-3-methylimidazolium Acetate and Cholinium Lysinate

The efficiency of the enzymatic digestibility of certain lignocellulosic biomass has been observed as a function of their structural and chemical changes which in turn depends on the ionic liquid (IL) used as the pretreatment solvent. This study demonstrated and compared the feasibility of the IL pretreatment process for two woody biomasses, namely maple and aspen, using two mechanistically distinct ILs, i.e., 1-ethyl-3-methylimidazolium acetate (C 2 mim][OAc]) and cholinium lysinate ([Ch][Lys]) as the solvent. The pretreatment was performed at three different temperatures of 100°C, 140°C, and 160°C at a high solid loading of 25 wt% to understand the impact of lignin content and crystallinity index on enzymatic digestibility. Saccharification of the biomass obtained after the IL pretreatment afforded 30–85% glucan conversions. For aspen, both [C 2 mim][OAc] and [Ch][Lys] exhibited the highest glucan conversion at 140°C. For maple, the highest glucan conversion was obtained at 140°C with [C 2 mim][OAc], whereas [Ch][Lys] had an optimum glucan conversion at 160°C. These pretreatments resulted in negligible delignification irrespective of the IL used. A significant loss of crystallinity was observed for all [C 2 mim][OAc]-pretreated biomasses, whereas the pretreatment with [Ch][Lys] resulted in an increase in the crystallinity index.

Choudhary, Hemant↗
DOE OSTI2022

Extended Accelerated Stress Testing (EAST) of Glass/Glass, Glass/Backsheet and Glass/Transparent Backsheet PV Modules: Influence of EVA and POE Encapsulants: Preprint

This paper presents the indoor extended accelerated stress testing (EAST) results of glass/glass (GG), glass/backsheet (GB) and glass/transparent backsheet (GT) modules having identical cells and two different encapsulant types, ethyl-vinyl-acetate (EVA) and polyolefin-elastomer (POE). Six 4-cell modules having the above-mentioned construction combinations were subjected to extended ultraviolet (UV; 600 kWh/m2), damp-heat (DH; 2000 hours) and thermal-cycling (TC; 600 cycles) tests. The post-stress UV fluorescent imaging, electroluminescent imaging, reflectance spectrophotometry and colorimetry results indicated that the grid finger degradation and encapsulant browning are slightly higher in the GG modules compared to the GB modules. The post-stress IV test results indicated, in general, that the GG/EVA modules tend to perform inferior to the GG/POE modules with the EAST evaluation.

EVA↗
DOE OSTI2021

Probing specificities of alcohol acyltransferases for designer ester biosynthesis with a high–throughput microbial screening platform

Alcohol acyltransferases (AATs) enables microbial biosynthesis of a large space of esters by condensing an alcohol and an acyl-CoA. However, substrate promiscuity of AATs prevents microbial biosynthesis of designer esters with high selectivity. Here, we developed a high-throughput microbial screening platform that facilitates rapid identification of AATs for designer ester biosynthesis. First, we established a microplate-based culturing technique with in situ fermentation and extraction of esters. We validated its capability in rapid profiling of the alcohol substrate specificity of 20 chloramphenicol acetyltransferase variants derived from Staphylococcus aureus (CAT Sa ) for microbial biosynthesis of acetate esters with various exogeneous alcohol supply. By coupling the microplate-based culturing technique with a previously established colorimetric assay, we developed a high-throughput microbial screening platform for AATs. We demonstrated that this platform could not only probe the alcohol substrate specificity of both native and engineered AATs but also identify the beneficial mutations in engineered AATs for enhanced ester synthesis. Here, we anticipate the high-throughput microbial screening platform provides a useful tool to identify novel wildtype and engineered AATs that have important roles in nature and industrial biocatalysis for designer bioester production.

2-phenhylethyl acetate↗
DOE OSTI2023

Transparent Conductive Encapsulants for Photoelectrochemical Applications

Utilizing sunlight to directly perform photoelectrochemical reactions is a promising route to renewable, net carbon-neutral fuels. However, a common problem with solar fuel production is semiconductor degradation in aqueous environments. An ideal protection layer should (1) prevent solution from reaching the semiconductor, (2) maintain charge transfer to and from solution, and (3) be transparent to light above the semiconductor band gap. While there have been substantial advances toward layers that meet these requirements, they are not easily adapted to new surfaces or new reactions, which can make protection difficult for newly developed photoabsorbers and (photo)electrochemical reaction pairings. In this work, we demonstrate the use of transparent conductive encapsulants (TCEs) to meet these requirements while also allowing for photoelectrode- and reaction-agnostic adaptability. TCEs are composed of an ethyl-vinyl acetate matrix with embedded conductive metal-coated microspheres that can be laminated to semiconductors. First, the electrochemical behavior of TCE-coated electrodes for the reduction of methyl viologen is characterized, demonstrating through-TCE electrical conduction. Then, photoelectrochemical measurements on TCE-protected semiconductors demonstrate the flexibility of this protection scheme. Finally, long-term photoelectrochemical measurements probe the efficacy of TCEs as protection layers. These findings demonstrate the potential of TCEs as adaptable protection layers in various photoelectrochemical applications.

14 SOLAR ENERGY↗
DOE OSTI2021

Lamination of transparent conductive adhesives for tandem solar cell applications

A transparent conductive adhesive (TCA) interlayer for mechanically stacked multijunction solar cells provides adhesive strength and electrical connection between sub-cells when stacked. The fabrication of TCA sheets from an ethyl-vinyl acetate (EVA) matrix and silver coated compliant conductive microspheres, similar to industry-standard EVA encapsulant sheets, compatible with a standard lamination process was developed. Blade coating TCA sheets using 3D printed blades and testing of vertical conduction through the interlayer with a TCA conductivity jig allowed for reproducible measurements and low-cost fabrication. The supplemental information provides design files to enable other researchers to produce their own blades and testing jigs. We identified 0.5 mm as an optimal blade height for producing lab-scale TCA sheets and 120 °C at 3 psi for 10 min as the optimal vacuum lamination process to minimize resistance and possible damage to samples. For TCA sheets with coverages between 0.75% and 9%, the series resistance was approximately 0.2 O cm2 which should result in minimal losses for one-sun photovoltaic applications.

14 SOLAR ENERGY↗
DOE OSTI2024

Imaging and Analysis of Insoluble Electrorefiner Material

Throughout pyroprocessing efforts at the Hot Fuel Examination Facility (HFEF), insoluble material has accumulated in the Electrorefiner (ER) vessel. The objective of this effort was to analyze the accumulated material to determine its origin. Material was removed from the ER salt bath and distilled to remove excess salt prior to performing analysis. Three samples were sent for chemical and isotopic analysis and underwent an ethyl acetate-bromine dissolution to segregate the oxide fraction from the metal fraction. Actinide concentrations were determined using a quadrupole–inductively coupled plasma–mass spectrometer (Q-ICP-MS). Three additional samples were sent for morphologic and elemental analysis by scanning electron microscopy (SEM) with Energy Dispersive X-ray (EDX) analysis at the Irradiated Materials Characterization Laboratory (IMCL). Analyses suggest that the material is primarily composed of UO2. with a small fraction of metal. This study draws no single conclusion as to the origin of the insoluble material in the ER. The particle sizes and morphologies observed in SEM micrographs indicate that the larger particles observed may be a result of introducing material to the ER that has not been completely reduced in Oxide Reduction (OR) operations, which precede electrorefining. Smaller particles may be due to reactions with oxygen and moisture present in HFEF. This research suggests that microscopic analysis of fuel particles before and after OR operations (including after distillation) as well as the uranium product collected on the cathode in the ER would increase understanding about particle morphology within the pyrochemical process.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS1985

Process development

An overview is given of seven process development activities which were presented at this session. Pulsed excimer laser processing of photovoltaic cells was presented. A different pulsed excimer laser annealing was described using a 50 w laser. Diffusion barrier research focused on lowering the chemical reactivity of amorphous thin film on silicon. In another effort adherent and conductive films were successfully achieved. Other efforts were aimed at achieving a simultaneous front and back junction. Microwave enhanced plasma deposition experiments were performed. An updated version of the Solar Array Manufacturing Industry Costing Standards (SAMICS) was presented, along with a life cycle cost analysis of high efficiency cells. The last presentation was on the evaluation of the ethyl vinyl acetate encapsulating system.

Bickler, D. B.↗
NASA NTRS1985

Encapsulation Processing and Manufacturing Yield Analysis

Evaluation of the ethyl vinyl acetate (EVA) encapsulation system is presented. This work is part of the materials baseline needed to demonstrate a 30 year module lifetime capability. Process and compound variables are both being studied along with various module materials. Results have shown that EVA should be stored rolled up, and enclosed in a plastic bag to retard loss of peroxide curing agents. The TBEC curing agent has superior shelf life and processing than the earlier Lupersol-101 curing agent. Analytical methods were developed to test for peroxide content, and experimental methodologies were formalized.

Willis, P.↗
DOE OSTI2021

Physics-based, neural network force fields for reactive molecular dynamics: Investigation of carbene formation from [EMIM + ][OAc - ]

Reactive molecular dynamics simulations enable detailed understanding of solvent effects on chemical reaction mechanisms and reaction rates. While classical molecular dynamics using reactive force fields allows significantly longer simulation time scales and larger system sizes compared with ab initio molecular dynamics, constructing reactive force fields is a difficult and complex task. In this work, we describe a general approach following the Empirical Valence Bond (EVB) framework for constructing ab initio reactive force fields for condensed phase simulations by combining physics-based methods with neural networks (PB/NN). The physics-based terms ensure correct asymptotic behavior of electrostatic, polarization, and dispersion interactions, and are compatible with existing solvent force fields. Neural networks are utilized for versatile description of short-range orbital interactions within the transition state region, and accurate rendering of vibrational motion of the reacting complex. Herein, we demonstrate our methodology for a simple deprotonation reaction of the 1-ethyl-3-methylimidazolium (EMIM+) cation with acetate to form 1-ethyl- 3-methylimidazol-2-ylidene and acetic acid. Our PB/NN force field exhibits ~ 1 kJ/mol MAE accuracy within the transition state region for the gas-phase complex. To characterize solvent modulation of the reaction profile, we compute potentials of mean force (PMFs) for the gas-phase reaction as well as the reaction within a four ion cluster, and benchmark against ab initio molecular dynamics simulations. We find that the surrounding ionic environment significantly destabilizes formation of the carbene product, and we show that this effect is accurately captured by the reactive force field. By construction, the PB/NN potential may be directly employed for simulations of other solvents/chemical environments without additional parameterization.

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

Ready Access to Anhydrous Anionic Lanthanide Acetates by Using Imidazolium Acetate Ionic Liquids as the Reaction Medium

Abstract Access to lanthanide acetate coordination compounds is challenged by the tendency of lanthanides to coordinate water and the plethora of acetate coordination modes. A straightforward, reproducible synthetic procedure by treating lanthanide chloride hydrates with defined ratios of the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium acetate ([C 2 mim][OAc]) has been developed. This reaction pathway leads to two isostructural crystalline anhydrous coordination complexes, the polymeric [C 2 mim] n [{Ln 2 (OAc) 7 } n ] and the dimeric [C 2 mim] 2 [Ln 2 (OAc) 8 ], based on the ion size and the ratio of IL used. A reaction with an IL : Ln‐salt ratio of 5 : 1, where Ln=Nd, Sm, and Gd, led exclusively to the polymer, whilst for the heaviest lanthanides (Dy−Lu) the dimer was observed. Reaction with Eu and Tb resulted in a mixture of both polymeric and dimeric forms. When the amount of IL and/or the size of the cation was increased, the reaction led to only the dimeric compound for all the lanthanide series. Crystallographic analyses of the resulting salts revealed three different types of metal‐acetate coordination modes where η 2 μκ 2 is the most represented in both structure types.

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

Ionic Liquid Sheath Stabilizes Atomically Dispersed Reduced Graphene Aerogel‐Supported Iridium Complexes during Ethylene Hydrogenation Catalysis

Abstract An atomically dispersed reduced graphene aerogel (rGA)‐supported iridium catalyst having reactive ethylene ligands was synthesized at an iridium loading of 9.9 wt % and coated with an ionic liquid, 1‐ethyl‐3‐methylimidazolium acetate ([EMIM][OAc]). Continuous‐scan X‐ray absorption spectra demonstrated that the iridium remained site‐isolated in flowing equimolar C 2 H 4 and H 2 during a temperature ramp to 100 °C. The data further showed the lack of detectable iridium aggregation when the feed was H 2 ‐rich or even pure H 2 at 100 °C. An Arrhenius plot determined for ethylene hydrogenation catalysis with the sample in flowing equimolar ethylene and hydrogen showed no variation in the apparent activation energy at temperatures up to 100 °C, confirming that the active sites remained intact at the higher temperatures. The results point to opportunities for overcoming the stability limitations of atomically dispersed supported noble metal catalysts by choice of electron‐donor supports and ionic liquid sheaths.

Kurtoğlu‐Öztulum, Samira F.↗
DOE OSTI2021

Chitin extracted from various biomass sources: It's not the same

Here this study demonstrates the use of ionic liquids to successfully extract chitin from different biomass sources and the utilization of the resulting chitins to prepare monofilament fibers. Chitin was extracted from five different biomass sources (processed and raw shrimp shell, crab and lobster shell, and fly larvae) using the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]). While processed and raw shrimp shell yielded chitin of high purity in quantitative yield, crab and lobster shell resulted in lower yields of chitin. Fly larva provided chitin severely contaminated with proteins. Each extracted chitin was re-dissolved in the same IL and dry wet jet spun into monofilament fibers to determine any trends in mechanical properties vs. biomass source. The concentration needed to spin fibers was not consistent and had to be adjusted individually for each type of chitin obtained. Chitin from raw shrimp shell produced the strongest fibers, while the chitin from the crab and lobster produced weaker fibers, although, the latter were twice as elastic. The use of fly larvae led to the weakest and least elastic fibers.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Ionic liquid-water mixtures enhance pretreatment and anaerobic digestion of agave bagasse

Agave bagasse (AB), a byproduct of tequila production, is a waste generated in large quantities and an emerging alternative for biofuels production. Nevertheless, the use of lignocellulosic biomass for this purpose requires a pretreatment that maximizes its degradation and utilization. Although there are several pretreatment types, using ionic liquids (IL) has become attractive due to its ability to dissolve the lignocellulosic biomass under mild conditions of time and temperature. As a drawback are the high cost of IL's and their high viscosity; thus mixing them with water is a way to overcome these hindrances. This work aimed to evaluate the effect of pretreatment with three diluted ILs on the A. tequilana bagasse structure and sugars production, as well as the potential of the enzymatic hydrolysate to produce methane in batch mode. The evaluated ILs were: 1-ethyl-3-methylimidazolium acetate [Emim][OAc], choline lysinate [Ch][Lys] and ethanolamine acetate [EOA][OAc]. The results showed that the IL with the best performance was [Ch][Lys], which not only offered the highest yields of sugar production (0.57 ± 0.03 g total sugars / g bagasse) but also, it is possible to use it at 30 % in a mix with water obtaining similar yields as with pure IL. Enzymatic hydrolysis of IL pretreated AB achieved 50.7 kg sugars and 49.3 kg of sugars for 90 %-[Ch][Lys] and 30 %-[Ch][Lys], respectively per 100 kg of untreated biomass. The enzymatic hydrolysate from the 30 %-[Ch][Lys] pretreated AB was able to achieve 0.28 L CH4/g CODfed, demonstrating that both sugar and methane yields are maintained when pure or 30 %-[Ch][Lys] are used for pretreatment, representing a step forward towards process feasibility.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Sandwiched Kagomé Lattices in a Coordination Polymer Based on Mixed-Valent Uranium

The metal–organic material U V O(U VI O 2 ) 2 (OH) 5 (Triaz) 2 (Triaz = 1,2,4-triazolate) has been isolated from the reaction of UO 2 (NO 3 ) 2 ·6H 2 O with 1,2,4-triazole in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C 2 mim][OAc]). The compound’s crystal structure is comprised of planar inorganic layers interconnected by organic linkers into a 3D framework. These layers represent a uranium-based coordination polymer with a Kagomé topology that to the best of our knowledge has never been recognized in f-element coordination chemistry.

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

Ionic-liquid-Assisted Fabrication of Lignocellulosic Thin Films with Tunable Hydrophobicity

Thin films with enhanced water repellency and mechanical strength can be fabricated from renewable lignocellulosic feedstock as a replacement for petrochemical-derived synthetic polymers, such that it minimizes life cycle impact on the environment and human health. In this work, hybrid poplar wood, either untreated (control) or pretreated with hot water at 160 °C for 20 min (HWE-20), 60 min (HWE-60), and 90 min (HWE-90), was dissolved in 1-ethyl-3-methylimidazolium acetate and regenerated to fabricate thin films. The HWE-90 films were enriched in lignin by 74%, specifically on the surface, which along with hemicellulose depletion imparted hydrophobicity (108° water contact angle) when compared to the control (56°), HWE-20 (77°), and HWE-60 (84°) films. They also exhibited 86% reduced water vapor sorption hysteresis and 75% improved storage modulus compared to the control. Thus, we demonstrate how to tune the lignocellulosic film properties via a combination of hot water pretreatment and ionic liquid dissolution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Draft Genome Assemblies of Ionic Liquid-Resistant Yarrowia lipolytica PO1f and Its Superior Evolved Strain, YlCW001

Adaptive laboratory evolution of Yarrowia lipolytica PO1f in the benchmark ionic liquid (IL; 1-ethyl-3-methylimidazolium acetate) produced a superior IL-tolerant microorganism, strain YlCW001. In this work, we report the genome sequences of PO1f and YlCW001 to explore the robustness of Y. lipolytica and its potential use as a microbial platform for producing fuels and chemicals.

59 BASIC BIOLOGICAL SCIENCES↗