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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Structural Design Variations in Beetle Elytra

Abstract Beetles typically use their protective wing coverings or elytra to shield their membranous hindwings from the environment. Elytra in some terrestrial species have evolved a greater protective role capable of shielding the organism from powerful antagonistic predators. The structure–function relationships of these biological composites identify how architectural and chemical variations of the cuticle are tuned to create light‐weight, impact resistant composites. Specifically, the elytral structures of a tree dwelling beetle capable of flight, Trypoxylus dichotomus , and a terrestrial beetle incapable of flight, Phloeodes diabolicus , are compared to understand how their varied environmental needs forged the elytra to facilitate fight or resist fatal predator strikes. Mechanical and microstructural analysis reveals P . diabolicus has a harder, stiffer elytra that incorporate through‐thickness fibers to resist greater mechanical stresses imposed by bending and puncture. Conversely, the elytra of T . dichotomus have a compliant structure with large voids that facilitates localized deformation. Variations in flexural strength and puncture resistance remain attributed to P . diabolicus possessing a thicker cuticle with a greater degree of cross‐linking and an increased amount of endocuticular layers. These findings may provide useful insight into the design and manufacturing of composite materials for use in light‐weight or energy‐absorbing applications.

Rivera, Jesus↗
DOE OSTI2022

Fermented Cerasus humilis fruits protect against high‐fat diet induced hyperlipidemia which is associated with alteration of gut microbiota

Abstract BACKGROUND Hyperlipidemia is regarded as a public health matter, and its effective prevention and treatment are urgently required. However, the treatment of hyperlipidemia is still relatively scarce. RESULTS Fermented Cerasus humilis fruit (FCHF) had higher total flavonoid, total phenolic, procyanidin, and organic and free amino acid content, and lower total sugar content, than non‐fermented C. humilis fruit (NFCHF). Both FCHF and NFCHF treatment significantly prevent putting on weight. Furthermore, FCHF administration ameliorated hyperlipidemia and cholesterol over‐accumulation. In addition, FCHF administration activated the antioxidase system and decreased the malondialdehyde content to relieve oxidative stress, and showed more efficaciously than NFCHF administration. FCHF treatments significantly reverse the fat deposition in high‐fat diet rat liver. FCHF supplementation can relieve the dysbacteriosis induced by hyperlipidemia, and regulate the composition of rat gut microbiota by increasing the abundance of Prevotella and norank_f_Muribaculaceae . CONCLUSION Lactobacillus plantarum and Saccharomyces cerevisiae fermentation enhanced the antihyperlipidemic property of C. humilis fruits by promoting gut microbiota regulation. © 2022 Society of Chemical Industry.

Wang, Yu↗
DOE OSTI2021

(2, 2) Scattering and the celestial torus

Analytic continuation from Minkowski space to (2, 2) split signature spacetime has proven to be a powerful tool for the study of scattering amplitudes. Here we show that, under this continuation, null infinity becomes the product of a null interval with a celestial torus (replacing the celestial sphere) and has only one connected component. Spacelike and timelike infinity are time-periodic quotients of AdS 3 . These three components of infinity combine to an S 3 represented as a toric fibration over the interval. Privileged scattering states of scalars organize into SL(2, $\mathbb{R}$) L ×SL(2, $\mathbb{R}$) R conformal primary wave functions and their descendants with real integral or half-integral conformal weights, giving the normally continuous scattering problem a discrete character.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2024

Multi-Source Machine Learning and Thermoplastics Enhanced Aerostructure Manufacturing (mTEAM)

RTX Technology Research Center (RTRC), together with Collins Aerospace (Collins) and Oak Ridge National Laboratory (ORNL) has developed an Artificial Intelligence (AI) / Machine Learning (ML) guided solution to advance the manufacturing and assembly of high performance and lightweight thermoplastic composite (TPC) aerospace products. The solution aims to lower risk, cost and lead time for induction heating based welding and consolidation processes for TPC structure. The cost and lead time of part and material specific process development for induction welding (IW) and induction consolidation will be reduced by replacing traditional empirical methods with optimization methods that merge AI/ML and physics-based process simulations and process experiments with sensing and controls. TPC-IW process development is empirical in nature, and uncertainties in material & process behavior exist near & far from the induction coil. Physics-based simulations can be leveraged directly for process optimization but can be too computationally expensive to run in high fidelity and real time to do robust process optimization. The key impact of successful TPC induction consolidation and welding is cost & lead time reduction for part & material specific consolidation and welding recipes. This is an enabler for more rapid deployment of TPC structures via joining assembly, which can reduce energy & cost intensive usage of autoclaves & ovens. The solution aimed to advance the U.S. Department of Energy’s interests in using thermoplastics and automation in composite manufacturing for improvement of products for existing markets via increased production speeds, reduced costs, and lowered use of energy. Welded TPC structures can offer significant weight & energy savings for high-value commercial aerospace & industrial applications compared to metal & thermoset composite structures assembled by mechanical fastening and/or adhesive bonding. The project was organized into two Budget Periods. Budget Period 1 (BP1) was 15 months and its goal was to perform ML process optimization framework development & deployment on lab-coupon aerostructure components. A Go/No-Go Review was performed at the end of BP1 to verify fulfilment of key tasks & milestones to justify a Go Decision to move into the next Budget Period. Budget Period 2 (BP2) was 12 months and its goal was the deployment of the ML framework for ML process optimization of pilot industrial scale aerostructure components. The overall project aim was to develop & demonstrate ML-enhanced modeling framework that learns process-property mapping from multiple data sources at different fidelities. During BP1, the team accomplished key tasks & milestones to demonstrate the concept of multi-source ML for TPC aerostructure consolidation and assembly. First, the team completed documentation of induction based TPC heating requirements including baseline metrics to compare measured results against. Next the team completed demonstration of data generation from physics-based simulations for ML surrogate model generation and demonstrated the integration of physics-based simulation data into multi-source AI/ML algorithms. In parallel, the team established the lab-coupon scale induction welding system and completed a process to label and reduce generated data from physics-based simulation and experiments for ML surrogate models to enable multi-source ML model training & testing. To complete BP1, the team integrated physics-based simulation data and experimental data into multi-source ML algorithms. This was based on the team completing ML deployment of the induction welding on a lab system at RTRC and AI/ML deployment on existing induction welding line at Collins. ORNL visited both Collins and RTRC sites to witness the TPC induction welding process. Then, ORNL designed and constructed a new version of their vision-based sensing system better adapted to acquire process signals of the TPC induction welding process for process anomaly and defect detection. In BP2, the team accomplished key tasks & milestones to scale up multi-source ML for TPC aerostructure consolidation and assembly from the lab-coupon scale to the pilot-industrial scale. In BP2, the team demonstrated real time anomaly & defect detection via experiments performed by ORNL & RTRC. The team completed ML-optimization heating trials for TPC induction consolidation at Collins, and the team confirmed pilot industrial scale experimental data from Collins was compatible with the developed ML pipeline from RTRC. The team completed sub-element scale ML process optimization demonstration at RTRC, where the team leveraged RTRC’s robotic TPC welding setup to de-risk the ML process optimization by performing ML analysis of recorded temperatures to account for complex part features. Then, the team applied its ML-derived control strategies and ML process optimization framework at Collins to the pilot-industrial scale on a demo skin-stiffener part representative of a nacelle aerostructure fan cowl section. The key innovation is the AI/ML framework enabling effective process development of high performance, lightweight, energy efficient TPCs for composite aircraft structures.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Low and High LET Degradation Studies of Metal-Loaded Organic Phase Ligands in the ALSEP Process

Organic solutions comprising the Actinide Lanthanide Separation Process (ALSEP) solvent consisting of 0.5 M 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) and 0.05 M N,N,N’,N’-tetra(2-ethylhexyl)diglycolamide (T2EHDGA) in n-dodecane were subjected to low LET and high LET irradiation before and after equilibration with an aqueous phase of 3 M HNO 3 . Degradation dose constants revealed greater ligand degradation due to gamma irradiation than alpha irradiation for both ligands. Furthermore, equilibration with nitric acid did not have a significant impact on ligand degradation for either irradiation source. Identified degradation products were similar for both gamma and alpha irradiation and occurred mostly through the rupture of the N–C carbonyl and C–O ether bonds for T2EHDGA and the C–Oether bond in HEH[EHP]. Acid contact appears to alter the degradation pathway by favoring the formation of higher molecular weight recombination products. Furthermore, mixed T2EHDGA-HEH[EHP]-NO 3 complexes were formed with Nd(III) after extraction from 3 M HNO 3 , and low LET gamma irradiation of the Nd(III) loaded organic solution produced similar degradation products as the organic solution absent of Nd(III). Interestingly, and likely due to the greater radiolytic susceptibility of T2EHDGA than HEH[EHP], a HEH[EHP]-Nd(III) complex appears to form as the T2EHDGA degrades with increasing absorbed dose.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Best practices for predictions of radionuclide activity concentrations and total absorbed dose rates to freshwater organisms exposed to uranium mining/milling

Predictions of radionuclide dose rates to freshwater organisms can be used to evaluate the radiological environmental impacts of releases from uranium mining and milling projects. These predictions help inform decisions on the implementation of mitigation measures. The objective of this study was to identify how dose rate modelling could be improved to reduce uncertainty in predictions to non-human biota. For this purpose, we modelled the activity concentrations of 210 Pb, 210 Po, 226 Ra, 230 Th, and 238 U downstream of uranium mines and mills in northern Saskatchewan, Canada, together with associated weighted absorbed dose rates for a freshwater food chain using measured activity concentrations in water and sediments. Differences in predictions of radionuclide activity concentrations occurred mainly from the different default partition coefficient and concentration ratio values from one model to another and including all or only some 238 U decay daughters in the dose rate assessments. Consequently, we recommend a standardized best-practice approach to calculate weighted absorbed dose rates to freshwater biota whether a facility is at the planning, operating or decommissioned stage. At the initial planning stage, the best-practice approach recommend using conservative site-specific baseline activity concentrations in water, sediments and organisms and predict conservative incremental activity concentrations in these media by selecting concentration ratios based on species similarity and similar water quality conditions to reduce the uncertainty in dose rate calculations. At the operating and decommissioned stages, the best-practice approach recommends relying on measured activity concentrations in water, sediment, fish tissue and wholebody of small organisms to further reduce uncertainty in dose rate estimates. This approach would allow for more realistic but still conservative dose assessments when evaluating impacts from uranium mining projects and making decision on adequate controls of releases.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2021

Probing Clustering Dynamics between Silicon and PAA or LiPAA Slurries under Processing Conditions

This work explores the complex interplay between slurry aggregation, agglomeration, and conformation (i.e., shape) of poly(acrylic acid) (PAA)- and lithiated PAA-based silicon slurries as a function of the shear rate and the resulting slurry homogeneity. These values were measured by small-angle neutron scattering (SANS) and rheology-coupled ultra-SANS at conditions relevant to battery electrode casting. Different binder solution preparation methods, either a ball milling (BM) process or a planetary centrifugal mixing (PCM) process, dramatically modify the resulting polymer dynamics and organization around a silicon material. This is due to the different energy profiles of mixing where the more violent and higher energy PCM causes extensive breakdown and reformation of the binder, which is now likely in a branched conformation, while the lower energy BM results in simply lower-molecular weight linear polymers. In conclusion, the breakdown and reorganization of the polymer structure affect silicon slurry homogeneity, which affects subsequent electrode architecture.

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

Determination of Carbon, Hydrogen, Nitrogen, and Oxygen in Bio-Oils: Laboratory Analytical Procedure (LAP)

The determination of total carbon, hydrogen, and nitrogen in bio-oils is important as these values can be used to track the carbon balance of production processes as well as calculate total oxygen content by difference. Oxygen content of bio-oils is a key metric for production and upgrading strategies as these are typically aimed at reducing oxygen. Oxygenates in bio-oils contribute to poor hydrocarbon miscibility, high acidity, high viscosity, and poor stability. Upgrading of bio-oils via deoxygenation produces hydrocarbons which can be used to generate feedstocks for renewable fuels and chemicals. In this Laboratory Analytical Procedure (LAP), combustion-based ultimate analysis is used to determine the weight percent (wt%) of C, H, and N in bio-oils and upgraded products. Ultimate analysis uses high temperatures and a pure oxygen environment to completely combust organic samples to carbon dioxide (CO 2 ), water (H 2 O), and nitrogen oxides (NO x ). In this procedure the amount of C and H in the sample are quantified by measuring resultant CO 2 and H 2 O with Fourier-transform infrared spectroscopy (FTIR). For N, NO x is reduced to nitrogen (N 2 ) which is measured with a thermal conductivity detector (TCD), providing total N content.

09 BIOMASS FUELS↗
DOE OSTI2022

Techno-economic analysis of non-aqueous hybrid redox flow batteries

Renewable energy has become indispensable to improving human life, but its growth is hampered by a lack of cost-effective energy storage systems to solve the intermittency problem. Non-aqueous hybrid redox flow batteries (NAqHRFBs), based on lithium metal anode and organic redox molecules (redoxmers), have been investigated as an attractive energy storage option because of their high cell voltages and energy densities compared to other redox flow battery candidates. However, little is known about the economic potential of NAqHRFBs, as well as the operational and materials impacts. This research establishes a techno-economic model to analyze the capital costs of NAqHRFBs with selected organic redoxmers, including 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). Sensitivity analyses for current density, area-specific resistance, cell voltage, electrolyte composition, redoxmer price, and equivalent molecular weight indicate the key factors in controlling NAqHRFB capital cost. To make the current NAqHRFB cost-effective, the first priority is to increase the operation current density over 10 times of those used in lab-scale tests, followed by adjusting redoxmer-related characteristics to afford more cost reduction space such as decreasing the unit price by ~20 fold. The results have shed light on potential material development and system engineering directions to make NAqHRFBs viable for renewable energy storage.

25 ENERGY STORAGE↗
DOE OSTI2022

Self-Organizing Map-Based Resilience Quantification and Resilient Control of Distribution Systems Under Extreme Events

Due to climate change, extreme weather events are occurring more frequently and with increasing impact. This trend poses a significant challenge for distribution system operators (DSO) to ensure that there is uninterrupted power supply to critical loads in their networks. To embed resilience into DSO's decision-making, resilience needs to be first quantified and then integrated into the system-level optimization. Therefore, this paper first develops a novel self-organizing map (SOM) based method (called SomRes) to quantify the time-varying resilience index of a system that can leverage the powerful classification property of SOMs and removes some of the disadvantages of subjective weight assignment methods. Using SomRes, a resilient resource allocation and operational dispatch algorithm is further developed to enhance system resilience against extreme events by considering the SomRes resilience index directly as the feedback. Here, the proposed resilience quantification approach is benchmarked with a state-of-the-art approach and the efficacy of the proposed resilient dispatch algorithm is demonstrated through several deterministic and statistical case studies on the IEEE 123-bus distribution system. Simulation studies show that the proposed SomRes quantification method is an appropriate indicator of system resilience, and the resilient resource allocation and dispatch strategy can significantly reduce critical load shedding under varying event propagation scenarios.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Evaluating efficacy of different UV-stabilizers/absorbers in reducing UV-degradation of lignin

Abstract Susceptibility of wood to UV degradation decreases the service life of wood products outdoors. Organic UV absorbers (UVAs) and hindered amine light stabilizers (HALSs), as well as inorganic UVAs, are added to coatings to improve the UV stability of coated-wood products. Although about 85% of UV radiation is absorbed by lignin in the wood, it is unclear which UV stabilizers can minimize lignin degradation. In this study, the photodegradation of softwood organosolv lignin was monitored over 35 days of UV exposure. Changes in lignin properties were assessed using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and phosphorus-31 nuclear magnetic resonance spectroscopy ( 31 P NMR). It was found that the aromatic rings of lignin underwent significant degradation, resulting in increased glass transition temperature and molecular weight of lignin. Subsequently, 18 different additives were mixed with lignin and exposed to UV irradiation. The analysis of samples before and after UV exposure with FTIR revealed that inorganic UVAs (cerium oxide and zinc oxide) and a mixture of organic UVAs and HALSs (T-479/T-292, T-5248, and T-5333) were the most effective additives in reducing lignin degradation. This study can help coating scientists to formulate more durable transparent exterior wood coatings.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Effect of Block Length on the Properties of Multiblock Polysulfone-Poly(diallylpiperidinium hydroxide) Anion Exchange Membranes

Research in anion exchange membranes (AEM)s has continued with the development of materials bearing base stable cations. Designing AEMs that microphase separate into hydroxide conductive, hydrophilic domains within a hydrophobic and mechanically robust matrix has been shown to be successful for improving AEM performance. A series of multiblock polysulfone-poly(diallylpiperidinium hydroxide) copolymers (PSf-PDApipOH) of similar hydrophobic/hydrophilic composition was prepared in which the molecular weight of the hydroxide conducting PDApipOH segments was varied. The variable hydrophilic segment molecular weight was designed to assess the impact on microphase separation, hydroxide conductivity, and water management. The multiblock copolymers investigated were prepared by condensation polymerization of preformed4-fluorophenyl sulfone terminated poly(diallylpiperidinium hexafluorophosphate) (PDApipPF6) oligomers with polysulfone monomers. The structure-property relationship between the molecular weight of the conductive PDApipOH segments and AEM performance was demonstrated by evaluation of the microphase separation, water uptake, and hydroxide conductivity. Further, membranes fabricated from the polysulfone-poly(diallylpiperidinium hexafluorophosphate) (PSf-PDApipPF6) multiblock copolymers were shown to form well-connected conductive domains by SAXS and atomic force microscopy experiments. The PSf-PDApipOH membranes were highly conductive with the maximum hydroxide conductivity reaching 62.9 mS∙cm -1 at 60°C and 95% relative humidity. Furthermore, it was demonstrated that the conductivity increased with increasing PDApipOH segment molecular weight.

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

The diurnally-averaged aerosol direct radiative effect and the use of the daytime-mean and insolation-weighted-mean solar zenith angles

Here, this study examines the application of the daytime-mean and insolation-weighted-mean solar zenith angles to calculate the diurnally-averaged aerosol direct radiative effect (DRE), DRE DA , for observed clear-sky conditions at the Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) and Tropical Western Pacific (TWP) sites. As compared with the reference calculation, the DRE DA are too strong (i.e., more negative) using daytime-mean solar zenith angles (DTMSZA) and are too weak (i.e., less negative) using insolation-weighted-mean solar zenith angles (IWMSZA). The biases in the DRE DA for DTMSZA (IWMSZA) are about -0.8 (0.7) W m -2 at the TOA and about -1.5 (0.9) W m -2 at the surface. Noting the mean TOA DRE DA of -2.85 W m -2 and the surface DRE DA of -7.09 W m -2 at SGP, the relative biases for DTMSZA (IWMSZA) are 26% (-24%) for the TOA DRE DA , and 17% (-11%) for the surface DRE DA . At TWP, the mean TOA DRE DA is -2.81 W m -2 and the surface DRE DA is -11.84 W m -2 which corresponds to relative biases for DTMSZA (IWMSZA) of 29% (-27%) for the TOA DRE DA and 15% (-9%) for the surface DRE DA . By introducing an adjusted insolation-weighted-mean solar zenith angle, the mean biases in the DRE DA at the TOA becomes -0.09 W m -2 and the biases in the DRE DA at the surface are about -0.41 W m -2 . Also presented are the effects of using the mean solar zenith angles on the shortwave (SW) upward fluxes at the TOA and SW downward fluxes at the surface in both clear-sky and pristine-clear-sky (i.e., gases only) conditions.

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

Fundamentals of Scalable Nanoparticle Assembly in Engineering Polymres

Systematically improving the properties of polymer nanocomposites is contingent on effectively controlling nanoparticle (NP) dispersion; further, it is necessary to attain this at scale if these methods are to impact practical applications. While most past work has focused on amorphous polymers, ≈ 70% of all polymers sold annually are semicrystalline. Inspired by this apparent disconnect, our work in the current DOE funded grant and this renewal proposal employs a novel handle, polymer crystallization, to organize NPs into the various amorphous zones of the lamellar semicrystalline morphology (interlamellar, interfibrillar and interspherulitic domains) of stereoregular polymers. We hypothesize that the isothermal crystallization rate of a polymer host, G, and NP diffusivity, are the two relevant control parameters in this context. In the case where the NPs are miscible in the melt, they remain spatially well-dispersed when the polymer is crystallized at a rate that is fast relative to NP diffusion. In contrast, monolayer-thick NP sheets with intersheet spacing of ~10-100nm form in slowly crystallized samples. This sheet stacking is remarkably similar to that seen in natural materials, e.g., Nacre. There is also ordering of the NPs at the larger interfibrillar scale. Importantly, the relative fraction of engulfed, interlamellar and interfibrillar NPs is determined by G. Further, the modulus of these materials can increase by a factor of 2-3 due to the organization state of the NPs, while leaving fracture toughness unaffected. We have established the broad applicability of this approach in two polymers, polyethylene (PE) and polyethyleneoxide (PEO). To achieve this goal we developed a method for grafting long PE chains from NPs with controlled graft density and molecular weight, giving us the ability to tailor their dispersion in the PE melt prior to crystallization. In this renewal proposal, we will develop the fundamental, quantitative understanding that will allow us to independently tailor polymer crystallization rate, NP diffusivity and NP agglomeration state in semicrystalline polymers so as to facilely control NP ordering and hence properties. A program that tightly integrates experiment and theory is proposed, and a key outcome of this research will be a three-dimensional design map for different regimes of NP organization (and hence properties) that can be achieved by polymer crystallization. A second independent outcome is the role of directional solidification and how it competes with the rates of polymer crystallization and NP mobility to affect the organization of the NP.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Reverse segregation and self-organization in inclined chute flows of bidisperse granular mixtures

In the usual segregation scenario for stable inclined chute flows of bidisperse mixtures of fine and coarse spherical particles, coarse particles rise toward the free surface, forming a coarse-rich region atop the flowing pile. Beyond a threshold coarse-to-fine diameter ratio of approximately 4, conversely, the weight of the coarse particles exceeds the segregation driving forces, causing individual coarse particles to sink within the pile and producing a reversed segregation state. However, an understanding of the collective evolution of the pile structure is still lacking when the particle diameter ratio exceeds 4 and the coarse-particle mass fraction is appreciable. To explore this broadly bidisperse limit, we perform discrete element method simulations considering mean particle diameter ratios of up to 8 and coarse-particle mass fractions spanning 0.1 to 0.9. The steady-state flow profiles reveal several intriguing behaviors that depend on the diameter ratio and mass fraction. These include a previously identified transition from usual to reverse segregation and a newfound tendency to self-organize into alternating coarse- and fine-rich particle layers stacked along the shear gradient direction, with layer thickness dictated by the coarse-particle diameter. A fuller understanding of segregation at this scale could pave the way for enhanced mixing or demixing techniques at the commercial scale.

granular flow↗
DOE OSTI2022

Metathesis, molecular redistribution of alkanes, and the chemical upgrading of low-density polyethylene

Here, a new strategy for polyethylene (PE) deconstruction via alkane metathesis is presented, in which WO x /SiO 2 catalyzes the olefin metathesis reaction step. Zeolite 4 A is an essential component to protect the metathesis active sites from poisoning by in-situ-generated oxygenates in a batch reaction system. High conversion of 1-hexadecene (96%) and n-hexadecane (92%)—surrogates of long-chain molecules—demonstrates the high reactivity of WO x /SiO 2 metathesis catalyst for olefin and alkane metathesis reactions, respectively, at moderate reaction temperatures of 300 °C for 2–3 h. Pretreatment temperature and length of the short n-alkane-chain solvent significantly affect the metathesis reactivity and selectivity. Results for the deconstruction of low-density PE (LDPE) in n-decane demonstrate a remarkable potential for PE upgrading with the advantages of short reaction times (3 h), the low mass ratio of solvent to LDPE, and the production of solid products with narrow molecular weight distributions.

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

The mechanical properties of Kel-F 800 (FK-800) as a function of crystallinity

Kel-F 800 is a copolymer of chlorotrifluoroethylene PTFE (75 wt. %) and vinylidene fluoride PVDF (25 wt. %). It has previously been used as a PBX binder for insensitive explosives such as PBX 9502 and LX-17. 3M started production of Kel-F 800 in 1957 and small-scale batches continued to be made until 2002 when production ceased due to environmental concerns regarding one of the emulsifiers used during production. Around 2000 the Kel-F 800 name was changed to FK-800 to avoid trademark concerns because rights to produce another polymer with a similar tradename (Kel-F 81) had been sold to another manufacturer. The Kel designation came from the original manufacturer of PCTFE (Kel-F 81), the Kellog company. To avoid confusion this document will only refer to Kel-F 800. In 2006, production of small-scale batches of Kel-F 800 was started again by 3M in response to customer enquiries. This new material, the first blended batch is referred to as LOT 1, was produced with a different emulsifier than used previously. Because Kel-F 800 is made in a small batch reactor, considerable variation in crystallinity can be expected from lot to lot and year to year. In many ways, this is not significant since the material is dissolved in a solvent (often MEK, ethylmethyl ketone or ethyl acetate) for PBX production purposes. This destroys the as received crystallinity and the resulting crystallinity in the processed material is a function of polymer molecular weight and thermal history. Producing large billets of Kel-F 800 from solvent extraction is not practical and so a compression molding technique has been used above the melting temperature. This method also removes residual crystallinity from the supplied granules. The molecular weight of a polymer can be estimated by several techniques, the most common being gel permittivity chromatography (GPC), size exclusion chromatography (SEC) and shear rheometry measurements of polymer/solvent solutions. Changes in molecular weight will affect the crystallization rate and the maximum crystallinity reached for a specific thermal history. Both references agree that the new LOT 1 material molecular weight falls within the deviation found from averaging previous historical lots of Kel-F 800.

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

A Hybrid Pathway to Biojet Fuel via 2,3-Butanediol

Production of biomass-derived sustainable alternative jet fuels (SAJF) has been considered as an important approach to decarbonize the aviation industry but still possesses various challenges in technology advancement, particularly in achieving high carbon efficiency. Here we report a hybrid pathway to SAJF from 2,3-butanediol (2,3-BDO), integrating biologically converting biomass to 2,3-BDO with catalytically upgrading of 2,3-BDO to jet-range hydrocarbons. This pathway is demonstrated to have a high carbon recovery to liquid hydrocarbons from corn stover (25–28%) (74–82% of the theoretical maximum efficiency). The catalytic conversion steps involve 2,3-BDO to C3+ olefins, oligomerization, and hydrogenation where the first two steps are the focus of this study. Under optimum reaction conditions (523 K, 115 kPa, 1.0 h-1 weight hourly space velocity), 2,3-BDO conversion and C3+ olefin selectivity are >97% and 94–98% during 40 h time on stream, respectively. To demonstrate the adaptability of this technology with bio-derived 2,3-BDO, we also investigated the impact of water and other organic coproducts (acetoin and acetic acid) inherited from the fermentation broth on the catalyst performance and product selectivities. We have shown that the catalyst can handle a significant amount of water in the liquid feed (40 wt% water/60 wt% 2,3-BDO) and maintain catalyst stability for ~40 h. Acetoin can be converted to similar C3+ olefins as 2,3-BDO with complete conversion of acetoin. Co-feeding 10 wt% acetoin with 2,3-BDO is found to have no impact on 2,3-BDO conversion, C3+ olefin selectivity, and catalyst stability. The utilization of organic coproduct like acetoin can help to improve overall carbon conversion efficiency when using real biomass-derived 2,3-BDO. On the other hand, the presence of 10 wt% acetic acid is shown to drastically inhibit methyl ethyl ketone (MEK) hydrogenation and butene oligomerization as revealed by the increased MEK and butene selectivities, implying the importance of separating organic acids when feeding bio-derived 2,3-BDO. The formed C3–C6 olefins from 2,3-BDO are further oligomerized over Amberlyst-36 catalyst to longer-chain hydrocarbons with >70 wt% jet-range hydrocarbons including predominantly iso-olefins/iso-paraffins. The overall carbon efficiency for the jet-range hydrocarbons is 19–22%, exceeding most of the reported biojet pathways, which makes it a promising approach for SAJF production.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗