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Results for “Aromatic Compounds”

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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Spherical Congeners of Polyaromatic Compounds Approaching C 20 - and C 60 -Fullerene-Type Structures

A series of three symmetric, hollow spherical, and shape-persistent molecular organic cages analogous to C 20 and C 60 were examined by computational modeling, analyzing structural elements, strain indicators, and physical properties relevant for potential applications. The compounds are covalent aromatic cages based on 1,3,5-substituted benzene nodes linked by paraphenylene or para-pyrenylene-connectors, with diameters varying from 2.3 to 4.2 nm. The apertures in the cage interior are varied by virtue of the cage type (C 20 - or C 60 -type cage) and the linear connectors placed between the C 6 H 3 -units. NBO and MESP analyses indicate the presence of electrophilic and nucleophilic sites in the molecular skeleton. In the cages with the phenylene-connectors, the HOMO−LUMO gaps are close to 4.0 eV. In the cage coated with an enlarged polyaromatic spacer (pyrene-unit), the gap is reduced by approximately 0.4 eV.

Aromatic compounds↗
DOE OSTI2024

Redox Activity Modulation in Extended Fluorenone-Based Flow Battery Electrolytes with π-π Stacking Effect

Redox flow battery shows promise for grid-scale energy storage. Aqueous organic redox flow batteries are particularly popular due to their potentially low material cost and safe water-based electrolyte. Commonly, redox active molecules used in this field feature aromatic rings, and increasing π-aromatic conjugation has been a popular strategy to achieve high energy density, high power density, and reduced crossover in new material design. However, this approach can inadvertently hinder redox activity depending on redox mechanism. This study reveals the underlying π-π stacking effect in extended aromatic redox active compounds, where aromatic radical intermediates are involved in the redox process. We report a molecular design strategy to mitigate the negative effect of π-π stacking by altering solvation dynamics and introducing molecular steric hindrance.

25 ENERGY STORAGE↗
NASA NTRS1990

Vinyl capped addition polyimides

Polyimide resins having improved thermo-oxidative stability are provided having aromatic vinyl end-caps. The polyimides are prepared by the reaction of a mixture of monomers comprising (1) a diamine, (2) an ester of tetracarboxylic acid and (3) an aromatic vinyl compound in a molar ratio of 1:2:3 of n: (n + 1):2 when the aromatic vinyl compound contains nitrogen and in a ratio of (n + 1):n:2 when the aromatic vinyl compound does not contain nitrogen, wherein n ranges from about 5 to about 20.

Vannucci, Raymond D.↗
DOE OSTI2026

Using Novosphingobium aromaticivorans for Concurrent Production of Intracellular and Extracellular Products from Aromatics Extracted from Poplar Biomass

Achieving high biochemical production in biotransformations of renewable resources requires using concentrated cultures that not only generate the product of interest but also produce abundant microbial cell waste. We explored the concept of gaining value from microbial cells by producing intracellular products in tandem with a desired extracellular product. Specifically, we engineered a strain ofNovosphingobium aromaticivorans to extracellularly produce 2-pyrone-4,6-dicarboxylic acid (PDC) from aromatic substrates and to intracellularly accumulate astaxanthin along with coenzyme Q 10 , all of which are products of industrial interest. Achieving the goal of concurrent production of intracellular and extracellular products required the creative application of bioreactor engineering principles. Although a continuously fed membrane bioreactor (MBR) maximized extracellular product biosynthesis, it had a negative effect on intracellular product accumulation. However, operating the MBR as a sequencing batch reactor (MBR-SBR) with a step-feed resulted in stable concurrent production of both extracellular and intracellular products. With aromatics extracted from poplar biomass, we achieved productivities of 1.14 g of PDC/L-h for the extracellular product and 0.04 mg of astaxanthin/L-h and 0.64 mg of CoQ 10 /L-h for intracellular products, respectively. Our findings demonstrate that the mode of operation of a bioreactor impacts the simultaneous production of intracellular and extracellular products byN. aromaticivorans.

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

Heteroatom-doped porous carbons for clean energy applications and methods for their synthesis

Methods for a facile, template free and one-step synthesis of nanoporous carbons by using a heterocyclic aromatic organic compound as a single source precursor of both carbon and nitrogen are described. The heterocyclic aromatic organic compound contains nitrogen in pyrrolic and/or pyridinic positions and is chemically activated with NaOH, KOH or ZnCl2 at high temperatures in a solid state mixture as a synthesis protocol to promote fine micropores during carbonization. Nanoporous carbons synthesized by these methods that have superior gas sorption/storage and energy storage properties are also described. The nanoporous carbons are useful as carbon sequestration agents and supercapacitors.

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

A chiral alkali metal capped Ni 4 cubane complex: Synthesis, structure, magnetic and catalytic bromination studies

A new chiral NaO 2 Ni 4 O 2 N 2 cluster has been developed with a distorted capped cubane-type structure. The structure was determined by single crystal X-ray diffraction. The tetradentate Schiff-base ligand was synthesized by the condensation of o-vanillin and $\textit{D}$-(-)–threo-2-amino-1-(4-nitrophenyl)-1,3-propanediol. X-ray structure reveals that the complex possesses a Ni 4 cubane cluster where sodium ion is anchored on the face of the cubane structure. Continuous shape measurement studies revealed that all the Ni centres are in distorted octahedral geometry and sodium ion adopts the spherical square pyramidal geometry. Further structural exploration reveals that the complex shows local distortions of the coordination geometries at each metal site, and these distortions govern the magnetic anisotropy associated with each Ni II ion. For the present case, an elongation ($d_{str}$ > 0) of the octahedral coordination sphere results in a local easy-plane anisotropy, with a positive $D_{Ni(II)}$ parameter. Temperature dependant magnetization measurements showed a predominant ferromagnetic interaction amongst the four Ni centres. This complex is also catalytically active towards bromination of aromatic phenolic compounds. Initial catalytic activity was verified with the conversion of phenol red to bromophenol blue. Different phenolic substances show good conversion to their corresponding bromo derivatives. The complex showed good catalytic activity towards bromination of aromatic phenolic compounds, offering up to 99% conversion with 100% selectively to their corresponding bromo derivatives.

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

Oxidation of phenolic compounds during autothermal pyrolysis of lignocellulose

Fast pyrolysis is traditionally defined as the rapid decomposition of organic material in the absence of oxygen to produce primarily a liquid product known as bio-oil. However, the introduction of small amounts of oxygen to the process holds prospects of internally generating the energy needed for pyrolysis. The present study investigates the partial oxidation of lignin-derived compounds during pyrolysis, which generates both carbon oxides and aromatic carbonyl compounds. Analysis of lignin derived phenolic compounds was performed to determine if the composition had changed under oxidative conditions. NMR analyses indicates aromatic carbonyls increased under oxidative conditions, with a corresponding decrease in phenolic hydroxyl groups. Finally, model phenolic compounds were pyrolyzed to help understand the role of partial oxidation during autothermal pyrolysis of lignocellulosic biomass.

09 BIOMASS FUELS↗
NASA NTRS1991

Polyimidazoles via aromatic nucleophilic displacement

Polyimidazoles (Pl) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethylacetamide, sulfolane, N-methylpyrroldinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperature under nitrogen. The di(hydroxyphenyl)imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl)imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxyphenyl)imidazole monomer. This synthetic route has provided high molecular weight Pl of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

Connell, John W.↗
NASA NTRS1992

Polyimidazoles via aromatic nucleophilic displacement

Polyimidazoles (PI) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl) imidazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as N,N-dimethyl acetamide, sulfolane, N-methylpyrrolidinone, dimethylsulfoxide, or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl) imidazole monomers are prepared by reacting an aromatic aldehyde with a dimethoxybenzil or by reacting an aromatic dialdehyde with a methoxybenzil in the presence of ammonium acetate. The di(methoxyphenyl) imidazole is subsequently treated with aqueous hydrobromic acid to give the di(hydroxphenyl) imidazole monomer. This synthetic route has provided high molecular weight PI of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides and dinitro compounds.

Connell, John W.↗
DOE OSTI2025

Analysis of semivolatile organics in liquid radioactive residue using sorptive stir bar and solvent back-extraction

Current methods for semivolatiles analysis in radioactive samples can produce large volumes of radioactive solvent residue. A method utilizing stir-bar sorptive extraction has been explored in this work for its applicability to radioactive waste samples. This low solvent analytical method may accelerate remediation, minimize hazardous solvent waste, and reduce exposure risk to workers. Organic compounds (polyaromatic hydrocarbons, chlorinated aromatics, and phenolic compounds) were chosen as surrogates for common Liquid Waste System (LWS) contaminants at Savannah River Site (Aiken, SC). Stir-bar extraction parameters (extraction time, matrix modification, and effective pH range) and solvent back extraction parameters (solvent type, volume, and extraction time) were optimized experimentally for the chosen compounds. Affinity of the stir-bar extraction polymer to radionuclides Cs-137 and Am-241 was observed to determine radionuclide concentration effects. The stir-bar method achieved mean recovery of 100 ± 0.7% (1σ), relative to 114 ± 7% using solvent extraction, while reducing weekly method hands-on time by 93.4% and solvent volume consumption by 99.3%. Sensitivity was improved by 378% in simulated tank waste and 278% in real-world LWS matrix, relative to solvent extraction. This work has produced a safe and optimized method for the low solvent analysis of organics in legacy radioactive tank waste by stir-bar sorptive extraction.

GC-MS↗
NASA NTRS1977

Trimerization of aromatic nitriles

Triazine compounds and cross-linked polymer compositions were made by heating aromatic nitriles to a temperature in the range of about 100 C to about 700 C, in the presence of a catalyst or mixture of catalysts. Aromatic nitrile-modified (terminated and/or appended) imide, benzimidazole, imidazopyrrolone, quinoxaline, and other condensation type prepolymers or their precopolymers were made which were trimerized with or without a filler by the aforementioned catalytic trimerization process.

Hsu, L. C.↗
DOE OSTI2020

Bio-reduction of ferrihydrite-montmorillonite-organic matter complexes: Effect of montmorillonite and fate of organic matter

Organic matter (OM) is often associated with Fe (hydr)oxides such as ferrihydrite (Fh) in soils and sediments, forming binary Fh-OM complexes. Microbial reduction of Fh results in destabilization of the complexes and mineral/OM transformation. However, little is known about the role of clay minerals in such processes, despite their common co-existence with Fh and OM in natural environments. Here Fh-OM complexes were synthesized in the presence of montmorillonite (SWy-2), forming ternary Fh-(SWy-2)-OM complexes. A metal-reducing bacterium Geobacter sulfurreducens was used to reduce Fh in the complexes under circumneutral pH and anoxic conditions with or without H 2 as extra electron donor. Various spectroscopy and mass spectrometry methods were used to monitor the progress of Fh bio-reduction and mineral/OM transformation. Results showed that G. sulfurreducens utilized mineral-bound OM as electron donor and/or carbon source to couple with Fh reduction. Relative to Fh-OM complex, Addition of SWy-2 to Fh-OM complex enhanced the bio-reduction extent of Fh by increasing the proportion of bioavailable OM that was weakly bound to SWy-2. However, its effect on the bio-reduction rate was variable. SWy-2 initially decreased the rate, because it spatially separated OM (electron donor) from Fh (electron acceptor). During later incubation, SWy-2 increased the reduction rate by sorbing biogenic Fe 2+ that would otherwise passivate the Fh and cell surfaces. Bio-reduction transformed mineral-bound OM to microbial products (e.g. necromass, extracellular polymeric substances), but organic compounds with aromatic structures, carboxyl groups and large molecular weight were more resistant to desorption and oxidation. The persistence of these compounds against bio-reduction induced transformation is likely due to their stronger binding with minerals and/or lower nominal oxidation states of carbon relative to other compounds. Our results provide new insights into the role of clay minerals in regulating biogeochemical cycling of solid-phase Fe and transformation of mineral-associated OM in anoxic soil environments.

58 GEOSCIENCES↗
DOE OSTI2022

Numerical Study of PAHs and Soot Emissions from Gasoline–Methanol, Gasoline–Ethanol, and Gasoline– n -Butanol Blend Surrogates

Soot formation is an intricate phenomenon, and soot propensity of a fuel is interwoven with the fuel composition, physical and chemical properties, and combustion environment. Here, the present study examines the hypothesis that in addition to the chemical composition of the fuel, the sooting nature of the fuel is closely coupled with its chemical property known as octane sensitivity (S). With this motivation, the present study numerically investigates the effects of gasoline surrogate composition and its property, octane sensitivity (S), on polycyclic aromatic hydrocarbons (PAHs) and soot emissions. Four-component toluene primary reference fuel (TPRF)–alcohol blends, comprising iso-octane, n-heptane, toluene, and one of the three different alcohols- methanol, ethanol, and n-butanol, are used as gasoline surrogates. A total of 320 TPRF–alcohol mixtures, with S in the range of 1–10, are examined under laminar counterflow diffusion flame conditions. A detailed chemical mechanism coupled with a comprehensive soot model, which includes reactions for soot inception, surface growth, PAH condensation, and oxidation, is adopted. The analysis indicates that the toluene content in the fuel mixture has a prominent effect, while the alcohol content and octane sensitivity of the fuel have a weak correlation with the PAHs and soot. Thus, it is not clear if any of these three variables, namely, toluene content in the fuel, alcohol content in the fuel, and S, are individually sufficient to characterize the PAHs and soot across various blends. For this reason, a new variable (X CHO ) based on the elemental composition of the fuel mixture is identified and it is shown that X CHO along with S of the fuel characterize soot emissions satisfactorily. Further, a reaction path analysis indicates that the efficacy of alcohols in reducing soot emissions follows the order: methanol > ethanol > n-butanol.

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

Performance of Base and Noble Metals for Electrocatalytic Hydrogenation of Bio-Oil-Derived Oxygenated Compounds

Electrocatalytic hydrogenation is a particularly attractive approach for converting the most unstable compounds in biogenic feedstocks at ambient conditions without external hydrogen. Here, we synthesized a variety of carbon-supported transition metal catalysts and characterized their activity for the electrocatalytic hydrogenation of a series of model compounds and pyrolysis oil. Carbonyl compounds, especially aromatic aldehydes, such as furfural and benzaldehyde, are particularly inclined to hydrogenation driven by an applied current. This was verified with pure solutions of the model compounds and with pyrolysis oil, where we achieved stable and steady continuous operation on Pd. By choosing the optimal catalyst composition, the conversion of benzaldehyde shifted from alcohol production (e.g., on Pd and Cu) to dimerization (e.g., on Co, Ni, and Zn). Pd and Cu were shown to offer the best compromise between reaction rates and efficiency although, in general, base metals offer similar conversions but better efficiencies that noble metals. Thus, the present work offers foundational results and guidelines for choosing the optimal metal catalyst and the applied potential for processing organic feedstocks as a function of its composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗