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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Controlling Reaction Routes in Noble‐Metal‐Catalyzed Conversion of Aryl Ethers

Abstract Hydrogenolysis and hydrolysis of aryl ethers in the liquid phase are important reactions for accessing functionalized cyclic compounds from renewable feedstocks. On supported noble metals, hydrogenolysis is initiated by a hydrogen addition to the aromatic ring followed by C−O bond cleavage. In water, hydrolysis and hydrogenolysis proceed by partial hydrogenation of the aromatic ring prior to water or hydrogen insertion. The mechanisms are common for the studied metals, but the selectivity to hydrogenolysis increases in the order Pd 2 pressure, thus, the selectivity to hydrogenolysis is maximized by increasing temperature and decreasing H 2 pressure. Selectivity to C−O bond cleavage reaches >95 % in water and alkaline conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Making a Splash in Homogeneous CO2 Hydrogenation: Elucidating the Impact of Solvent on Catalytic Mechanisms

Molecular catalysts for hydrogenation of CO2 are widely studied as a means of chemical hydrogen storage. Catalysts are traditionally designed from the perspective of controlling the ligands bound to the metal. In recent years, studies have shown that the solvent can also play a key role in the mechanism of CO2 hydrogenation. A prominent example is the impact of the solvent on the thermodynamic hydride donor ability, or hydricity, of metal hydride complexes reletive to the hydride acceptor ability of CO2. In some cases, simply changing from an organic solvent to water can reverse the direction of hydride transfer between a metal hydride and CO2. Additionally, the solvent can impact catalysis by converting CO2 into carbonate species, as well as activate intermediate products for hydrogenation to more reduced products. By understanding the substrate and product speciation, as well as the reactivity of the catalyst towards the substrate, the solvent can be used as a central design component for the rational development of new catalytic systems. This research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

carbon dioxide, homogeneous catalysis, solvent eff↗
DOE OSTI2024

Bifunctional Metal‐Organic Nanoballs Featuring Lewis Acidic and Basic Sites as a New Platform for One‐Pot Tandem Catalysis

Abstract The design and synthesis of polyhedra using coordination‐driven self‐assembly has been an intriguing research area for synthetic chemists. Metal‐organic polyhedra are a class of intricate molecular architectures that have garnered significant attention in the literature due to their diverse structures and potential applications. Hereby, we reportCu‐MOP, a bifunctional metal‐organic cuboctahedra built using 2,6‐dimethylpyridine‐3,5‐dicarboxylic acid and copper acetate at room temperature. The presence of both Lewis basic pyridine groups and Lewis acidic copper sites imparts catalytic activity to Cu‐MOP for the tandem one‐pot deacetalization‐Knoevenagel/Henry reactions. The effect of solvent system and time duration on the yields of the reactions was studied, and the results illustrate the promising potential of these metal‐organic cuboctahedra, also known as nanoballs for applications in catalysis.

Chemistry↗
DOE OSTI2018

A Critical Review on Superoxide-Based Sodium–Oxygen Batteries

Sodium superoxide (NaO 2 ) based sodium oxygen batteries (Na-O 2 ) possess high theoretical energy density and high energy efficiency that can be an alternative energy storage device to lithium ion batteries (LIBs). However, the state-of-the-art sodium oxygen batteries is still far from real application due to the limited understanding of the cell chemistry and reaction mechanism. In this mini review, we will review the recent advances on NaO 2 based Na-O 2 batteries, especially focusing on the reaction mechanism and the stability of NaO 2 . The parasitic reactions from the highly active NaO 2 will be discussed. We believe this review will provide insightful understanding on the mechanism and the role of the discharge product in NaO 2 batteries.

25 ENERGY STORAGE↗
DOE OSTI2019

Structural Characterization and Magnetic Properties of SrCo{sub 2}Fe{sub 16}O{sub 27} Hexaferrite Synthesized by Citric Acid Sol-Gel Method

The W -type SrCo{sub 2}Fe{sub 16}O{sub 27} (SCFO) hexagonal ferrite samples were prepared by the sol-gel method using metal nitrate as raw material, citric acid as complexing agent, and water as solvent. The effects of different sintering temperatures and holding times on the phase composition and morphology properties were explored in detail by using the X-ray diffractometer and field emission scanning electron microscope. The X-ray diffraction, microstructure, and magnetic performance of most optimum sintering temperature and holding time of preparing single-phase SCFO hexagonal ferrite were investigated. The experimental results indicate that the best optimum sintering temperature and holding time of SCFO hexagonal ferrite are 1280 °C and 4 h, respectively. Field emission scanning electron microscopy results indicate that the size of the particles is about 5–10 μ m. The result of magnetic measurement shows that SCFO hexagonal ferrite exhibits the soft magnetic property and the Curie temperature (T{sub C}) is ∼ 850 K. Furthermore, by analyzing the Arrott plot, the phase transition near the T{sub C} is a secondary phase transition.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Optimizing Native Ion Mobility Q-TOF in Helium and Nitrogen for Very Fragile Noncovalent Structures

The amount of internal energy imparted to the ions prior to the ion mobility cell influences the ion structure and thus the collision cross section. Non-covalent complexes with few internal degrees of freedom and/or high charge densities are particularly sensitive to collisional activation. Here, we investigated the effects of virtually all tuning parameters of the Agilent 6560 IM-Q-TOF on the arrival time distributions of ubiquitin{sup 7+} and found conditions in which the native state prevails. We discuss the effects of solvent evaporation conditions in the source, of the entire pre-IM DC voltage gradient, of the funnel RF amplitudes. We also report on ubiquitin{sup 7+} conformations in different solvents, including native supercharging conditions. Collision-induced unfolding (CIU) can be conveniently provoked either behind the source capillary or in the trapping funnel. The softness of the instrumental conditions behind the mobility cell was further optimized with the DNA G-quadruplex [(dG{sub 4}T{sub 4}G{sub 4}){sub 2}·(NH{sub 4}{sup +}){sub 3}-8H]{sup 5−}, for which ion activation results in ammonia loss. To reduce the ion internal energy and obtain the intact 3-NH{sub 4}{sup +} complex, we reduce the post-IM voltage gradient, but this results in a lower IM resolving power due to increased diffusion behind the drift tube. The article describes the various trade-offs between ion activation, ion transmission, and ion mobility performance for native MS of very fragile structures. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2025

Oxidation of n-alkanes using TS-1 and H 2 O 2 : Effects of chain length and solvents

The selective oxidation of n-C 8 H 18 , n-C 12 H 26 , n-C 16 H 34 , n-C 20 H 42 , and n-C 36 H 74 was studied with a goal of using these as models to provide insight into how to functionalize polyolefins. Reactions were carried out using a TS-1 catalyst and H 2 O 2 in a batch reactor with different cosolvents, including methanol, acetone, acetonitrile, methyl ethyl ketone, and methyl butyl ketone. Rates decreased with increasing alkane size, possibly due to the reduced solubility of larger alkanes into the water-rich phases. Cosolvents that promote the partitioning of alkanes in the aqueous phase increased the rates. 1 H NMR spectroscopy demonstrated that ketones were the primary products, although some alcohols also formed. There was preferential reaction at the 2 position in the alkanes, but reaction at central carbons was also observed. The results of this study suggest strategies for using this catalytic chemistry to functionalize polyolefins.

Alkane oxidation↗
DOE OSTI2022

Integrated lignocellulosic biorefinery for efficient production of furans and photothermal materials

Integrated lignocellulosic biorefineries offer a great potential to valorize all the components in lignocellulose into products, including fuels, chemicals, and materials. However, because of lignocellulose recalcitrance, conversion of bioresources remains a techno-economic challenge for many lignocellulosic biorefineries. In this work, we have proposed a sustainable and profitable biorefinery strategy for lignocellulose fractionation and conversion. In this design, a biphasic solvent consisting of a molten salt hydrate LiCl·4H 2 O and γ-valerolactone (GVL) was initially used for separating hemicellulose from lignocellulose. More interestingly, 100 wt% of biorefinery products from lignin were directly converted to functional photothermal materials by coordinating with Fe 3+ for solar-thermal-electricity conversion. Attributed to this rational design, we report the techno-economic analysis predicts a revenue of 439.3 USD by processing 100 kg of lignocellulosic biomass using the above developed method.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Understanding the influence of solvents on the Pt-catalyzed hydrodeoxygenation of guaiacol

Bio-oil derived from fast pyrolysis of lignocellulosic biomass needs to be deoxygenated to become a substitute for petroleum fuels. Here, we study the hydrodeoxygenation mechanism of guaiacol, a bio-oil model compound derived from the lignin fraction of biomass, on Pt(1 1 1) terrace sites in the presence of water, diethyl ether, 1-butanol, and n-hexane as solvent. Using first-principles periodic density functional theory (DFT) calculations and mean-field microkinetic reactor modeling, a detailed reaction mechanism is investigated targeting various products such as catechol, phenol, anisole, benzene, cyclohexanone, and cyclohexanol. Solvent phase DFT outcomes are mostly similar to that of the vapor phase; however, microkinetic modeling results suggest that rate controlling species and transition states differ somewhat in the various reaction environments. Catechol was found to be the major aromatic product across all reaction environments. Over Pt(1 1 1), unsaturated monooxygenate production from catechol is unlikely.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Systematic design and research on a series of cadmium coordination polymers assembled due to tetracarboxylate ligands

A series of metal-organic frameworks (MOFs) have been prepared by tetracarboxylate ligands and Cd(II) ions under the hydrothermal or solvothermal conditions with the formulas of {[Cd_2(L_1)(H_2O)_4]·H_2O}{sub n} (1), {[(CH_3)_2NH_2]_2[Cd(L_1)]}{sub n} (2), [Cd(L{sub 2}){sub 0.5}(H{sub 2}O)]{sub n} (3), {[(CH_3)_2NH_2]_2 [Cd(L_2)]·2DMF}{sub n} (4), [Cd(L{sub 3}){sub 0.5}(H{sub 2}O)]{sub n} (5), {[Cd(L_3)_0_._5(H_2O)]·CH_3OH}{sub n} (6), {[(CH_3)_2NH_2]_2[Cd_3(L_4)_2]}{sub n} (7) (H{sub 4}L{sub 1}=[1,1′:4′,1″-terphenyl]-2,2″,5,5″-tetracarboxylic acid; H{sub 4}L{sub 2}=[1,1′:4′,1″-terphenyl]-2′,4,4″,5′-tetracarboxylic acid; H{sub 4}L{sub 3}=[1,1′:3′,1″-terphenyl]-2′,3,3″,5′-tetracarboxylic acid; H{sub 4}L{sub 4}=[1,1′:4′,1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid), which are characterized by single-crystal X-ray diffraction, elemental analyses, IR, TGA and PXRD. Complex 1 exhibits a three-dimensional (3D) supramolecular framework based on two-dimensional (2D) coordination networks. Complexes 2 and 4 possess 3D framework based on the 1D right-handed helix channels. Complexes 3 and 7 are a 3D architecture containing two different channels. Isostructural complexes 5 and 6 display 3D framework. The different synthetic methods and coordination modes of the tetracarboxylates ligands have effect on formation of various MOFs. Moreover, the luminescent properties and N{sub 2} adsorption behaviors have been reported. - Graphical abstract: A series of cadmium(II) high-dimensional coordination polymers constructed from four different kinds of tetracarboxylate ligands have been successfully prepared under hydrothermal or solvothermal conditions. The effect of solvents, the coordination modes of the tetracarboxylates and positions of carboxylate groups on the architectures of complexes 1–7 have been investigated in detail. The luminescent properties of the part of complexes, N{sub 2} adsorption behaviors of complexes 2, 4–7 have also been studied. - Highlights: • Tetracarboxylate ligands based on terphenyl moiety have been used. • Several factors that influenced the architecture have been discussed. • Luminescent properties have been investigated.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Photocatalysts Based on Cobalt-Chelating Conjugated Polymers for Hydrogen Evolution from Water

Developing photocatalytic systems for water splitting to generate oxygen and hydrogen is one of the biggest chemical challenges in solar energy utilization. In this work, we report the first example of heterogeneous photocatalysts for hydrogen evolution based on in-chain cobalt-chelating conjugated polymers. Four conjugated polymers chelated with earth abundant cobalt ions were synthesized and found to evolve hydrogen photocatalytically from water. These polymers are designed to combine functions of the conjugated backbone as light-harvesting antenna and electron transfer conduit with the in-chain bipyridyl chelated transition metal centers as catalytic active sites. In addition, these polymers are soluble in organic solvents, enabling effective interactions with the substrates as well as detailed characterization. We also found a polymer-dependent optimal cobalt chelating concentration at which the highest photocatalytic hydrogen production (PHP) activity can be achieved.

Li, Lianwei↗
DOE OSTI2026

Untapped Benefits of Porous Liquids for Gas Capture: Low-Energy Regeneration

Current liquid-phase gas capture materials incur high operational costs due to energy-intensive regeneration processes, creating an industrial need for alternative materials that retain engineering benefits while reducing energy requirements. Porous liquids (PLs), liquid-phase materials with permanent internal porosity, have emerged as promising replacements with excellent gas absorption capacity and selectivity. Despite these benefits, evaluation of regeneration in PLs remains rare. In this Perspective, we evaluate the effects of solvent interactions, mass transport, and binding site formation that control PL regeneration. While conventional regeneration methods exist in PLs, the diversity of PL compositions allows for novel regeneration processes including light irradiation via use of photosensitive azobenzene-based cages, isostatic compression to collapse internal pore structures, and localized heating via sonication for gas desorption. In conclusion, the wide variability in porous host materials that generate the internal porosity in PLs facilitates innovative low-energy regeneration pathways, positioning them as a transformative solution in separation technologies.

gas capture↗
DOE OSTI2019

Electrochemical Studies of Selected Lanthanide and Californium Cryptates

Efforts to quantitatively reduce Cf III → Cf II in solution as well as studies of its cyclic voltammetry have been hindered by its scarcity, significant challenges associated with manipulating an unusually intense γ emitter, small reaction scales, the need for nonaqueous solvents, and its radiolytic effects on ligands and solvents. In an effort to overcome these impediments, we report on the stabilization of Cf II by encapsulation in 2.2.2-cryptand and comparisons with the readily reducible lanthanides, Sm 3+ , Eu 3+ , and Yb 3+ . Cyclic voltammetry measurements suggest that Cf III/II displays electrochemical behavior with characteristics of both Sm III/II and Yb III/II . The °E 1/2 values of −1.525 and −1.660 V (vs Fc/Fc + in tetrahydrofuran (THF)) for [Cf(2.2.2-crypt)] 3+/2+ and [Sm(2.2.2-crypt)] 3+/2+ , respectively, are similar. However, the ΔE values upon complexation by 2.2.2-cryptand for Cf III/II more closely parallels Yb III/II with postencapsulation shifts of 705 and 715 mV, respectively, whereas the shift of Sm III/II (520 mV) mirrors that of Eu III/II (524 mV). This suggests more structural similarities between Cf II and Yb II in solution than with Sm II that likely originates from more similar ionic radii and local coordination environments, a supposition that is corroborated by crystallographic and extended X-ray absorption fine structure measurements from other systems. Competitive-ion binding experiments between Eu III/II , Sm III/II , and Yb III/II were also performed and show less favorable binding by Yb III/II . Connectivity structures of [Ln(2.2.2-cryptand)(THF)][BPh 4 ] 2 (Ln = Eu II , Sm II ) are reported to show the important role that THF plays in these redox reactions.

ethers↗
DOE OSTI2024

Thermodynamic Analysis of Silk Fibroin–Graphite Hybrid Materials and Their Morphology

Silk fibroin (SF) is a β-sheet-rich protein that is responsible for the remarkable tensile strength of silk. In addition to its mechanical properties, SF is biocompatible and biodegradable, making it an attractive candidate for use in biotic/abiotic hybrid materials. A pairing of particular interest is the use of SF with graphene-based nanomaterials (GBNs). The properties of this interface drive the formation of well-ordered nanostructures and can improve the electronic properties of the resulting hybrid. It was previously demonstrated that SF can form lamellar nanostructures in the presence of graphite; however, the equilibrium morphology and associated driving interactions are not fully understood. Here, in this study, we characterize these interactions between SF and SF lamellar with graphite using molecular dynamics (MD) simulations and umbrella sampling (US). We find that SF lamellar nanostructures have strong orientational and spatial preferences on graphite that are driven by the hydrophobic effect, destabilizing solvent–protein interactions and stabilizing protein–protein and protein–graphite interactions. Finally, we show how careful consideration of these underlying interactions can be applied to rationally modify the nanostructure morphology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗