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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Pyrolysis and oxidation of aromatic compounds

A study of the questions associated with the use of alternate fuels demands knowledge of the chemical mechanism of pyrolysis and oxidation of aromatic compounds. Both pyrolysis and oxidation are important, because fuel-rich conditions may mean that pyrolysis is competitive with oxidation. Soot formation is certainly a pyrolysis problem. The complexity of system characteristics makes a detailed study of thermodynamical and kinetic conditions difficult. The matter can be simplified somewhat by generalizing the chemistry by classes of molecules. The criteria for such a generalization of the chemistry are discussed along with an evaluation of the rate constants and their temperature and pressure dependences. Attention is given to the pyrolysis of hydrocarbons, the oxidation of hydrocarbons, the oxidation reactions of alkanes, aspects of codification and extrapolation, group additivity, structural consideration, kinetics, and the pyrolysis of aromatic compounds.

Golden, D. M.↗
NASA NTRS1967

Organic compounds in meteorites. II.

Aromatic compounds in benzene eluate fractions from carbonaceous chondrites by high resolution capillary gas-liquid chromatography

GAS CHROMATOGRAPHY↗
NASA NTRS1980

Ambient cure polyimide foams prepared from aromatic polyisocyanates, aromatic polycarboxylic compounds, furfuryl alcohol, and a strong inorganic acid

Flame and temperature resistant polyimide foams are prepared by the reaction of an aromatic dianhydride, e.g., pyromellitic dianhydride, with an aromatic polyisocyanate, e.g., polymethylene polyphenylisocyanate (PAPI) in the presence of an inorganic acid and a lower molecular weight alcohol, e.g., dilute sulfuric acid or phosphoric acid and furfuryl alcohol. The exothermic reaction between the acid and the alcohol provides the heat necessary for the other reactants to polymerize without the application of any external heat. Such mixtures, therefore, are ideally suited for in situ foam formation, especially where the application of heat is not practical or possible.

Sawko, Paul M.↗
NASA NTRS1983

Shock Tube Studies of Soot Formation

The objective of this research is to record the time histories of the major and minor species which appear in the pyrolysis of toluene, benzene, butadiene, allene, and acetylene; to develop a set of reactions that will model the observed profiles over a wide temperature and concentration range; to identify the critical reactions that influence the pre-particle soot formation process. Toluene and benzene were chosen as two key aromatic compounds which are representative of the pyrolytic process. Butadiene, allene, and acetylene were selected to investigate the formation of aromatic compounds from non-cyclic species. The experimental apparatus used for the study consists of a shock tube coupled to a time-of-flight mass spectrometer Spectra are recorded at 30 microsecond intervals for a total observation time of 0.50 - 1.20 milliseconds. Peak heights of the species of interest in the m/e range 12-300 are measured as a function of reaction time. Calibration curves are constructed which aid the conversion of peak heights to concentrations. The mixtures range from 1 percent-6 percent fuel; the balance is neon diluent.

R D Kern↗
NASA NTRS1982

Incombustible resin composition

Incombustible resin compositions composed of aromatic compounds were obtained through (1) combustion polymer material and (2) bisphenol A or halogenated bisphenol A and bisphenol A diglycidl ether or halogenated bisphenol A diglycidyl ether. The aromatic compound is an adduct of bifunctional phenols and bifunctional epoxy resins.

Akima, T.↗
NASA NTRS1975

Friction differences between aliphatic and aromatic structures in lubrication of titanium

Sliding friction experiments were conducted with a titanium (0001) single crystal surface with various adsorbed aliphatic and aromatic compounds containing the same number of carbon atoms. An Auger emission spectroscopy analysis was used to monitor the presence of the organic lubricating compounds. Results of the investigation indicate that hexane and benzene give the same friction coefficients over a range of loads. At light loads the friction decreased with an increase in the halogen atom size where the halogens chlorine, bromine, and iodine are incorporated into the benzene molecular structure. The aliphatic compounds chlorohexane and bromohexane exhibited lower friction coefficients than the aromatic structures chlorobenzene and bromobenzene.

Buckley, D. H.↗
NASA NTRS1974

Hydrocarbons identified in extracts from estuarine water accommodated no. 2 fuel oil by gas chromatography-mass spectrometry

Results are presented on a computerized gas chromatograph-mass spectrometer analysis of methylene chloride and n-heptane extracts of a No. 2 fuel oil accommodated estuarine water sample. The analytical method is briefly described, and the limitations on the identifications are categorized. Some attempt was made to determine major and trace constituents in the water accommodate. Altogether 66 hydrocarbon compounds were identified specifically, and 75 compounds were partially identified. Seven compounds could be recognized as major constituents of the water accommodated oil and ten were present only as traces. The aromatic compounds found were alkyl benzenes, naphthalene, tetralin, indane, biphenyl, fluorene, anthracene, and some of their alkyl substituted isomers in the range of carbon numbers C7 to C15. Four n-alkanes, C10 to C13, were found along with four other assorted hydrocarbons.

Lewis, B. W.↗
NASA NTRS1966

Thermodynamic Equilibrium in the Origin of Organic Matter

Theoretical and experimental support is presented for the hypothesis that organic compounds occurring in carbonaceous chondrites may have formed under equilibrium or near equilibrium conditions. The equilibrium distributions of organic compounds at temperature between 300 and 1000 K and pressures of 10(exp 16) to 50 atmospheres for the C-H-O system have been computed. At high temperatures and low pressures aromatic compounds may form even in the presence of excess hydrogen. Equilibrium concentrations of numerous compounds possible at 1000 K when N, S, and C1 are added to the system have also been determined. A limited equilibrium method is employed in which those few compounds which form with most difficulty are excluded from the computations. This approach is shown to be useful in the interpretation of certain experimental data. In preliminary experiments it has been found that gases, converted to the plasma state by high energy radio frequency discharge, yield product mixtures which are in qualitative agreement with those predicted.

CHEMICAL EQUILIBRIUM↗
NASA NTRS1966

Process for preparing dispersions of alkali metals

Finely divided particles of alkali metals are produced by combining alkali metals with certain aromatic compounds in selected solvents to form low-temperature soluble complexes from which the pure alkali metals precipitate quantitatively when the solutions are warmed. All operations must be carried out in an inert gas atmosphere.

Landel, R. F.↗
NASA NTRS1973

Volatile terpenoids from aeciospores of Cronartium fusiforme.

Identification of the terpenoids present in the volatile fraction from aeciospores of the gall rust fungus Cronartium fusiforme. The major monoterpenoid hydrocarbons found to be present with only traces of camphene include alpha-pinene, beta-pinene, delta(3)-carene, myrcene, linonene, beta-phellandrene, and delta-terpinene. A number of monoterpenoid alcohols, acyclic sesquiterpenes, and aromatic compounds were also present.

Laseter, J. L.↗
NASA NTRS1978

Characteristics and combustion of future hydrocarbon fuels

As the world supply of petroleum crude oil is being depleted, the supply of high-quality crude oil is also dwindling. This dwindling supply is beginning to manifest itself in the form of crude oils containing higher percentages of aromatic compounds, sulphur, nitrogen, and trace constituents. The result of this trend is described and the change in important crude oil characteristics, as related to aircraft fuels, is discussed. As available petroleum is further depleted, the use of synthetic crude oils (those derived from coal and oil shale) may be required. The principal properties of these syncrudes and the fuels that can be derived from them are described. In addition to the changes in the supply of crude oil, increasing competition for middle-distillate fuels may require that specifications be broadened in future fuels. The impact that the resultant potential changes in fuel properties may have on combustion and thermal stability characteristics is illustrated and discussed in terms of ignition, soot formation, carbon deposition flame radiation, and emissions.

Rudey, R. A.↗
NASA NTRS1979

Synthesis of triaryltrifluoroethanes

Article discusses preparation of triary1-2,2,2-trifluoroethants prepared from a,a,a-trifluoroacetone by condensation with various substituted aromatic compounds. Compounds are useful as they have high thermal stability.

Rosser, R. W.↗
NASA NTRS1978

Characteristics and combustion of future hydrocarbon fuels

Dwindling supply of high-quality crude is beginning to manifest itself in the form of crude oils containing higher percentages of aromatic compounds, sulfur, nitrogen, and trace constituents. In the present paper, problems which have arisen with regard to the hydrogen content in jet fuels derived from these crude oil sources are discussed, with particular reference to the effects of varying the fuel properties on the combustion and thermal stability characteristics of a fuel. The importance of knowing how severe the effects of variations in hydrogen content, fuel-bound-nitrogen content, and boiling range are on such combustion phenomena as soot and carbon formation, emissions, and ignition is pointed out.

Rudey, R. A.↗
NASA NTRS1981

Mutagens and carcinogens - Occurrence and role during chemical and biological evolution

The roles of mutagenic and carcinogenic substances in early biologic evolution is examined, along with terrestrial and extraterrestrial sources of mutagens and carcinogens. UV solar radiation is noted to have served to stimulate prebiotic life while also causing harmful effects in plants and animals. Aromatic compounds have been found in meteorites, and comprise leukemogens, polycyclic hydrocarbons, and nitrasamine precursors. Other mutagenic sources are volcanoes, and the beginning of evolution with mutagenic substances is complicated by the appearance of malignancies due to the presence of carcinogens. The atmosphere of the Precambrian period contained both mutagens and early carcinogens and, combined with volcanic activity discharges, formed an atmospheric chemical background analogous to the background ionizing radiation. Carcinogenesis is concluded to be intrinsic to nature, having initiated evolution and, eventually, cancer cells.

Giner-Sorolla, A.↗
NASA NTRS1965

Organic compounds in carbonaceous chondrites.

Aromatic hydrocarbons in carbonaceous chondrites investigated by time-of-flight mass spectrometry and hypothesized as formed in solar nebula under thermodynamic equilibrium

AROMATIC COMPOUND↗