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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Polynorbornene-based polycations

A statistical, cationic-functionalized norbornene copolymer is formed by a process including performing a vinyl addition polymerization in the presence of a metal catalyst of a first norbornene monomer substituted with a first alkyl group and at least a second norbornene monomer substituted with a second alkyl group, to form an intermediate norbornene copolymer. The second alkyl group includes a substituent which undergoes a substitution reaction with a precursor of a cationic group. The process further includes adding the precursor for the cationic group to the intermediate norbornene copolymer to form the cationic functionalized norbornene copolymer. The cationic group has a volume of 0.25 cm 3 /mol or greater (for example, a phosphonium group or an imidazolium group).

Noonan, Kevin↗
DOE OSTI2022

Intramolecular hydrogen bonding analysis

The quasi-atomic orbital (QUAO) bonding analysis is used to study intramolecular hydrogen bonding (IMHB) in salicylic acid and an intermediate that is crucial to the synthesis of aspirin. The bonding analysis rigorously explores IMHB through directly accessing information that is intrinsic to the molecular wave function, thereby bypassing the need for intrinsically biased methods. The variables that affect the strength of IMHB are determined using kinetic bond orders, QUAO populations, and QUAO hybridizations. Important properties include both the interatomic distance between hydrogen and oxygen participating in the IMHB and the hybridization on the oxygen. The bonding analysis further shows that each intramolecular hydrogen bond is a four-electron three-center bond. Here, the bonding analysis is used to understand how aromatic reactivity changes due to the effect of functional groups on the aromatic ring.

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

Revealing Reaction Pathways of Collective Substituted Iron Fluoride Electrode for Lithium Ion Batteries

Metal fluorides present a high redox potential among the conversion-type compounds, which make them specially work as cathode materials of lithium ion batteries. To mitigate the notorious cycling instability of conversion-type materials, substitutions of anion and cation have been proposed but the role of foreign elements in reaction pathway is not fully evaluated. In this work, we explored the lithiation pathway of a rutile-Fe 0.9 Co 0.1 OF cathode with multimodal analysis, including ex situ and in situ transmission electron microscopy and synchrotron X-ray techniques. Our work revealed a prolonged intercalation–extrusion–cation disordering process during phase transformations from the rutile phase to rocksalt phase, which microscopically corresponds to topotactic rearrangement of Fe/Co–O/F octahedra. During this process, the diffusion channels of lithium transformed from 3D to 2D while the corner-sharing octahedron changed to edge-sharing octahedron. DFT calculations indicate that the Co and O cosubstitution of the Fe 0.9 Co 0.1 OF cathode can improve its structural stability by stabilizing the thermodynamic semistable phases and reducing the thermodynamic potentials. We anticipate that our study will inspire further explorations on untraditional intercalation systems for secondary battery applications.

25 ENERGY STORAGE↗
DOE OSTI2022

Computational Predictions of the Hydrolysis of 2,4,6-Trinitrotoluene (TNT) and 2,4-Dinitroanisole (DNAN)

Hydrolysis is a common transformation reaction that can affect the environmental fate of many organic compounds. In this study, three proposed mechanisms of alkaline hydrolysis of 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroaniline (DNAN) were investigated with plane-wave density functional theory (DFT) combined with ab initio and classical molecular dynamics (AIMD/MM) free energy simulations, Gaussian basis set DFT calculations, and correlated molecular orbital theory calculations. Most of the computations in this study were carried out using the Arrows web based tools. For each mechanism: Meisenheimer complex formation, nucleophilic aromatic substitution, and proton abstraction reaction energies and activation barriers were calculated for the reaction at each relevant site. For TNT, it was found that the most kinetically favorable first hydrolysis steps involve Meisenheimer complex formation by attachment of OH$^{-}$ at the C1 and C3 arene carbons and proton abstraction from the methyl group. The nucleophilic aromatic substitution reactions at the C2 and C4 arene carbons were found to be thermodynamically favorable. However, the calculated activation barriers were slightly lower than previous studies, but still found to be $\Delta$G$^{\ddagger} \approx 18$ kcal/mol using PBEo AIMD/MM free energy simulations, suggesting the reactions are not kinetically significant. For DNAN, the barriers of nucleophilic aromatic substitution were even greater ($\Delta$G$^{\ddagger} > 29$ kcal/mol PBEo AIMD/MM). Further, the most favorable hydrolysis reaction for DNAN was found to be a two-step process in which the hydroxyl first attacks the C1 carbon to form a Meisenheimer complex at the C1 arene carbon C1-(OCH$_3$)OH$^{-}$, subsequently, the methoxy anion (-OCH$_3$) at the C1 arene carbon dissociates and the proton shuttles from the C1-OH to the dissociated methoxy group, resulting in methanol and an aryloxy anion.

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

Study of self-interaction-errors in barrier heights using locally scaled and Perdew-Zunger self-interaction methods

We study the effect of self-interaction errors on the barrier heights of chemical reactions. For this purpose we use the well-known Perdew-Zunger [J. P. Perdew and A. Zunger, Phys. Rev. B,23, 5048 (1981)] self-interaction-correction(PZSIC), as well two variations of the recently developed, locally scaled self-interaction correction (LSIC) [Zope et al.,J. Chem. Phys.151, 214108 (2019)] to study the barrier heights of the BH76 benchmark dataset. Our results show that both PZSIC and especially the LSIC methods improve the barrier heights relative to the local density approximation(LDA). The version of LSIC that uses the iso-orbital indicator z as a scaling factor gives a more consistent improvement than an alternative version that uses an orbital-dependent factor based on the ratio of orbital densities to the total electron density. We show that LDA energies evaluated using the self-consistent and self-interaction-free PZSIC densities can be used to assess density-driven errors. Furthermore, the LDA reaction barrier errors for the BH76 set are found to contain significant density-driven errors for all types of reactions contained in the set, but the corrections due to adding SIC to the functional are much larger than those stemming from the density for the hydrogen transfer reactions and of roughy equal size for the non-hydrogen transfer reactions.

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

Bimolecular Reaction of Methyl-Ethyl-Substituted Criegee Intermediate with SO 2

Methyl-ethyl-substituted Criegee intermediate (MECI) is a four-carbon carbonyl oxide that is formed in the ozonolysis of some asymmetric alkenes. MECI is structurally similar to the isoprene-derived methyl vinyl ketone oxide (MVK-oxide) but lacks resonance stabilization, making it a promising candidate to help us unravel the effects of size, structure, and resonance stabilization that influence the reactivity of atmospherically important, highly functionalized Criegee intermediates. We present experimental and theoretical results from the first bimolecular study of MECI in its reaction with SO 2 , a reaction that shows significant sensitivity to the Criegee intermediate structure. Using multiplexed photoionization mass spectrometry, we obtain a rate coefficient of (1.3 ± 0.3) × 10 –10 cm 3 s –1 (95% confidence limits, 298 K, 10 Torr) and demonstrate the formation of SO 3 under our experimental conditions. Through high-level theory, we explore the effect of Criegee intermediate structure on the minimum energy pathways for their reactions with SO 2 and obtain modified Arrhenius fits to our predictions for the reaction of both syn and anti conformers of MECI with SO 2 (k syn = 4.42 × 10 11 T –7.80 exp(-1401/T) cm 3 s –1 and k anti = 1.26 × 10 11 T –7.55 exp(-1397/T) cm 3 s –1 ). In conclusion, our experimental and theoretical rate coefficients (which are in reasonable agreement at 298 K) show that the reaction of MECI with SO 2 is significantly faster than MVK-oxide + SO 2 , demonstrating the substantial effect of resonance stabilization on Criegee intermediate reactivity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Production of a δ-Lactam from Glucose through Integrating Biological and Chemical Catalysis

We present a new strategy for the production of a δ-lactam from glucose that integrates biological production of triacetic acid lactone (TAL, 4-hydroxy-6-methyl-2H-2-one) with catalytic transformation of TAL into 6-methylpiperidin-2-one (MPO) through metabolic engineering, isomerization, amination, and catalytic hydrogenation/hydrogenolysis. We developed a sustainable and antibiotic-free fed-batch fermentation using genetically modified Rhodotorula toruloides IFO0880. This process achieved a yield of 2-hydroxy-6-methyl-4H-pyran-4-one (2H4P) at 0.05 g/g of glucose, corresponding to a 9.9 g/L titer. By adjusting the pH of the fermentation broth to 2, 2H4P was quantitatively converted into TAL. The TAL in the fermentation broth was directly converted by aminolysis into 4-hydroxy-6-methylpyridin-2(1H)-one (HMPO), which achieved an 18.5% yield with 94.3% purity. The HMPO yield was lower in the fermentation broth than in a clean feedstock (32.2%), suggesting that the biological impurities are inhibitors in this reaction. Further investigation revealed that lower pH levels and reduced TAL concentrations in the fermentation broth significantly decreased HMPO yields. Subsequently, the precipitated HMPO was filtered and dried and then subjected to the final catalytic conversion in H2O solvent, achieving a MPO yield of 91.8%. Furthermore, this integrated approach demonstrated the direct use of TAL in the filtered aqueous fermentation broth without the need to isolate TAL.

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

Influence of Intracrystalline Ionic Strength in MFI Zeolites on Aqueous Phase Dehydration of Methylcyclohexanols

Abstract The impact of the concentration of hydrated hydronium ions and in turn of the local ionic strength in MFI zeolites has been investigated for the aqueous phase dehydration of 4‐methylcyclohexanol (E1 mechanism) and cis ‐2‐methylcyclohexanol (E2 mechanism). The E2 pathway with the latter alcohol led to a 2.5‐fold higher activity. The catalytic activity normalized to the hydronium ions (turnover frequency, TOF) passed through a pronounced maximum, which is attributed to the increasing excess chemical potential of the alcohols in the pores, increasing in parallel with the ionic strength and the additional work caused by repulsive interactions and charge separation induced by the bulky alcohols. While the maximum in rate observed is invariant with the mechanism or substitution, the reaction pathway is influencing the activation parameters differently.

Milaković, Lara↗
DOE OSTI2021

Influence of Intracrystalline Ionic Strength in MFI Zeolites on Aqueous Phase Dehydration of Methylcyclohexanols

Abstract The impact of the concentration of hydrated hydronium ions and in turn of the local ionic strength in MFI zeolites has been investigated for the aqueous phase dehydration of 4‐methylcyclohexanol (E1 mechanism) and cis ‐2‐methylcyclohexanol (E2 mechanism). The E2 pathway with the latter alcohol led to a 2.5‐fold higher activity. The catalytic activity normalized to the hydronium ions (turnover frequency, TOF) passed through a pronounced maximum, which is attributed to the increasing excess chemical potential of the alcohols in the pores, increasing in parallel with the ionic strength and the additional work caused by repulsive interactions and charge separation induced by the bulky alcohols. While the maximum in rate observed is invariant with the mechanism or substitution, the reaction pathway is influencing the activation parameters differently.

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

Back Cover: Influence of Intracrystalline Ionic Strength in MFI Zeolites on Aqueous Phase Dehydration of Methylcyclohexanols (Angew. Chem. Int. Ed. 47/2021)

Here the impact of the concentration of hydrated hydronium ions and in turn of the local ionic strength in MFI zeolites has been investigated for the aqueous phase dehydration of 4-methylcyclohexanol (E1 mechanism) and cis-2-methylcyclohexanol (E2 mechanism). The E2 pathway with the latter alcohol led to a 2.5-fold higher activity. The catalytic activity normalized to the hydronium ions (turnover frequency, TOF) passed through a pronounced maximum, which is attributed to the increasing excess chemical potential of the alcohols in the pores, increasing in parallel with the ionic strength and the additional work caused by repulsive interactions and charge separation induced by the bulky alcohols. While the maximum in rate observed is invariant with the mechanism or substitution, the reaction pathway is influencing the activation parameters differently.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Mechanistic Studies of Ligand Substitution, Linkage Isomerism, and Insertion Reactions in Electron Rich Pd(II) Complexes of a Zwitterionic Diimine Ligand

We have prepared cationic palladium complexes possessing a new zwitterionic ligand bis-N,N’–1-(2,4,6-triphenylpyridyl) oxalamide [(N ^ N)Pd(Me)(L)] + [BArF] - , (BArF=3,5-(CF 3 ) 2 C 6 H 3 , L=NCMe, CO). The structure of [(N ^ N)Pd(Me)(CO)] + [BArF] - was determined by X-ray diffraction analysis. Energy Decomposition Analysis (EDA) indi-cates this N ^ N zwitterionic ligand is more electron-donating relative to bidentate diimine ligands. Low temperature NMR analysis shows the existence of linkage isomers with the N ^ N isomer the most stable. Structures were assigned using NMR and DFT analysis. Barriers to interconversion of isomers are ΔG ‡ = 10-12 kcal/mol. Kinetics of acetoni-trile displacement from [(N ^ N)Pd(Me)(NCCH 3 )] + [BArF] - by CD 3 CN, ethylene and t Bu 3 P were measured and mechanisms of exchange determined. The ethylene complex, [(N ^ N)Pd(Me)(C 2 H 4 )] + was generated at -45 °C, and the barrier of migrato-ry insertion determined at 0 °C (ΔG ‡ = 23.4 kcal/mol) and compared to related diimine complexes. The methyl carbonyl complex undergoes migratory insertion in the presence of CO at -70 to -55 °C (ΔG ‡ = ca. 15.7 kcal/mol) to yield the acyl carbonyl complex. Furthermore, the neutral bis-trimethylsilylmethyl complex [(N ^ N)Pd(CH 2 SiMe 3 ) 2 was prepared and characterized by X-ray diffraction analysis. It displays dynamic behavior at very low temperatures in the NMR spectrum (-90 °C, ΔG ‡ =7.9 kcal/mol) which, supported by DFT analysis, is ascribed to rotation of the bulky -CH 2 SiMe 3 groups.

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

Initiating a Roadmap for Solar Fuels R&D: Imagining Beyond Thermochemical Cycles

Sandia National Laboratories in collaboration with the National Renewable Energy Laboratory outline a framework for developing a solar fuels roadmap based on novel concepts for hybridizing gas-splitting thermochemical cycle s with high-temperature electro chemical steps. We call this concept SoHyTEC, a Solar Hybrid Thermochemical-Electrochemical Cycle. The strategy focuses on transforming purely thermochemical cycles that split water (H 2 O) and carbon dioxide (CO 2 ) to produce hydrogen (H 2 ) and carbon monoxide (CO) , respectively, the fundamental chemical building blocks for diverse fuels and chemicals , by substituting thermochemical reactions with high-temperature electrochemical steps. By invoking high-temperature electrochemistry, the energy required to complete the gas-splitting cycle is divided into a thermal component (process temperature) and an electrical component (applied voltage). These components, sourced from solar energy, are independently variable knobs to maximize overall process efficiency. Furthermore, a small applied voltage can reduce cycle process temperature by hundreds of degrees , opening the door to cost-effective solar concentrators and practical receiver/reactor de signs. Using the SoHyTEC concept as a backdrop, we outline a framework that advocates developing methods for automating information gathering, critically evaluating thermochemical cycles for adapting into SoHyTEC, establishing requirements based on thermodynamic analysis, and developing a model-based approach to benchmarking a SoHyTEC system against a baseline concentrating solar thermal integrated electrolysis plant. We feel these framework elements are a necessary precursor to creating a robust and adaptive technology development roadmap for producing solar fuels using SoHyTEC. In one example, we introduce high-temperature electrochemistry as a method to manipulate a fully stoichiometric two-step metal oxide cycle that circumvents costly separation processes and ultra-high cycle temperatures. We also identify and group water-splitting chemistries that are conceptually amenable to hybridization.

14 SOLAR ENERGY↗
DOE OSTI2022

Effect of iron substitution in cryptomelane on the heterogeneous reaction with isoprene

Biogenic isoprene is an important pollutant for regional air quality. Being ubiquitously distributed on the earth surface, manganese (hydr)oxides should play a vital role in the transformation of isoprene. Cryptomelane is a typical manganese oxide with isomorphous substitution of Fe for Mn, but less attention has been paid to its heterogeneous reaction with isoprene. When Fe 3+ replaces Mn 3+ , K + is depleted and Mn 3+ is oxidized to Mn 4+ . In contrast, oxygen vacancies are formed when Fe 3+ substitutes Mn 4+ . Fe substitution creates weak crystallites and abundant mesopores, resulting in the increase of isoprene adsorption. As found by theoretical calculations, the Mn 4+ –O 2- bonds at the cross sections of the tunnels is more active than that on the outer wall of the tunnels. After the adsorption of isoprene, bridging carboxylate species and hydrogen-bonding water are produced and the surface octahedra are distorted, i.e., Mn 4+ O 6 → Mn 3+ O 6-δ . As the heat facilitates the breakage of Mn 4+ –O 2- , the increase of environmental temperature enhances the oxidation of isoprene. Here the above findings shed light on the effect of Fe substitution in cryptomelane to enhance the oxidation of isoprene, and illustrates that heterogeneous reaction with isoprene impairs the transformation of other environmental substances on cryptomelane.

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

Rhodium-Catalyzed Alkenylation of Arenes with Multi-Substituted Olefins: Comparison of Selectivity and Reaction Rate as a Function of Olefin Identity

Rhodium-catalyzed arene alkenylation using Cu(II) carboxylates as the in situ oxidant and mono-substituted olefins has been previously reported (e.g., J. Am. Chem. Soc. 2019, 139, 5474; J. Am. Chem. Soc. 2018, 140, 17007; Organometallics 2019, 38, 3860; J. Am. Chem. Soc. 2020, 142, 10534). Herein, studies are extended to multi-substituted olefins with the goal of evaluating the effect of olefin substitution pattern and substituent identity on selectivity and turnover frequency. The influence of olefin substitution is probed by comparing the conversion of benzene to alkenyl arenes with ethylene, propylene, 1-butene, cis-2-butene, trans-2-butene, isobutene, 2-methyl-2-butene, and tetramethylethylene as well as the phenyl-substituted olefins and isomers of propenylbenzene. The rate of oxidative hydrophenylation for multi-substituted olefins follows the trend monosubstituted > disubstituted > trisubstituted, and tetrasubstituted olefins are unreactive. To probe the effect of substituent size on Markovnikov/ anti-Markovnikov regioselectivity, cyclohexyl, tert-butyl, isopropyl, ethyl, and methyl substituted α-olefins are compared. Selectivity for anti-Markovnikov products generally increases as substituent steric bulk is increased. Tolerance for some functionalized olefins is demonstrated. Here, the ortho/meta/para regioselectivity with mono-substituted arenes reveals that arene and olefin identity influences selectivity. Further mechanistic studies provide evidence for Curtin–Hammet control of ortho/meta/para regioselectivity with monosubstituted arenes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗