Showing papers on "Hydrocarbon published in 1987"
TL;DR: The intermediates detected are consistent with both toluene and benzene degradation via initial oxidation by ring hydroxylation or methyl oxidation (toluene), which would result in the production of phenol, cresols, or aromatic alcohol.
Abstract: The aromatic hydrocarbons toluene and benzene were anaerobically transformed by mixed methanogenic cultures derived from ferulic acid-degrading sewage sludge enrichments. In most experiments, toluene or benzene was the only semicontinuously supplied carbon and energy source in the defined mineral medium. No exogenous electron acceptors other than CO2 were present. The cultures were fed 1.5 to 30 mM unlabeled or 14C-labeled aromatic substrates (ring-labeled toluene and benzene or methyl-labeled toluene). Gas production from unlabeled substrates and 14C activity distribution in products from the labeled substrates were monitored over a period of 60 days. At least 50% of the substrates were converted to CO2 and methane (greater than 60%). A high percentage of 14CO2 was recovered from the methyl group-labeled toluene, suggesting nearly complete conversion of the methyl group to CO2 and not to methane. However, a low percentage of 14CO2 was produced from ring-labeled toluene or from benzene, indicating incomplete conversion of the ring carbon to CO2. Anaerobic transformation pathways for unlabeled toluene and benzene were studied with the help of gas chromatography-mass spectrometry. The intermediates detected are consistent with both toluene and benzene degradation via initial oxidation by ring hydroxylation or methyl oxidation (toluene), which would result in the production of phenol, cresols, or aromatic alcohol. Additional reactions, such as demethylation and ring reduction, are also possible. Tentative transformation sequences based upon the intermediates detected are discussed.
486 citations
Patent•
14 Sep 1987
TL;DR: In this paper, the upgrading and conversion of a viscous heavy hydrocarbonaceous crude oil into lighter hydrocarbons is accomplished in a continuous reactor system and may be accomplished in underground petroleum reservoir at supercritical temperature and pressure.
Abstract: A majority amount of a heavy hydrocarbon crude is reacted with a minor amount of brine, at supercritical temperature and pressure for the brine, for a predetermined period of time in order to upgrade and convert the heavy hydrocarbon crude into a lighter hydrocarbon crude of higher API gravity. The upgrading and conversion of a viscous heavy hydrocarbonaceous crude oil into lighter hydrocarbons is accomplished in a continuous reactor system and may be accomplished in a subterranean petroleum reservoir at supercritical temperature and pressure. The overall heat of reaction is neutral, i.e., neither exothermic nor endothermic. In order to provide the necessary temperature, heat is added to the system prior to the reaction. For an in situ application, a combustion operation may be utilized to provide the necessary temperature, and is initiated using an oxidizing gas injected through an injection well. After a predetermined amount of time, injection of the oxidizing gas is terminated and the injection well is shut-in for a predetermined period of time to permit the petroleum reservoir to undergo a soak period in order to increase the temperature and decrease the viscosity of the viscous heavy hydrocarbonaceous crude oil. As the viscosity of the heavy hydrocarbonaceous crude oil decreases, the oil flows downwardly into the combustion zone steam and/or brine is injected which is at supercritical conditions in order to upgrade the heavy hydrocarbonaceous crude oil into lighter fractions. The reaction products from a reactor or an in situ operation are also lower in obnoxious constituents such as sulfur, nitrogen and heavy metals.
310 citations
TL;DR: In situ infrared spectra of methanol and dimethyl ether in H-ZSM-5 and Na-Z SM-5 were reported in this paper, showing that methanol reacts with internal acidic hydroxyl groups at 523 K to form a methoxy species correlated with the onset of hydrocarbon formation.
Abstract: In situ infrared spectra are reported of methanol and dimethyl ether in H-ZSM-5 and Na-ZSM-5. Methanol reacts with internal acidic hydroxyl groups at 523 K to form a methoxy species, the appearance of which correlated with the onset of hydrocarbon formation. Dimethyl ether is protonated is lower temperatures but forms the same methoxy species at 473 K. The methoxy species methylates benzene and alkenes at 523 K. The implications of these observations for the mechanism of hydrocarbon formation are discussed.
285 citations
TL;DR: In this paper, the authors describe an electroreduction of CO at a Cu cathode in aqueous solutions, which allows an effective cathodic reduction of CO to form hydrocarbons and alcohols with appreciable current densities.
Abstract: Carbon monoxide is a substance of primary importance from the viewpoint of utilization of carbon resources. Hydrogenation of CO in the gas phase has been widely studied, but only a small number of papers has been published about electrochemical reduction. Electroreduction of CO did not proceed effectively according to the previous papers, the cathodic partial currents for electroreduction of CO were very small, not exceeding 5 x 10/sup -5/ A cm/sup -2/. They briefly describe here an electroreduction of CO at a Cu cathode in aqueous solutions. This procedure allows an effective cathodic reduction of CO to form hydrocarbons and alcohols with appreciable current densities.
277 citations
TL;DR: In this paper, positive and negative ions of the type C2n (30⩽2n⌽210) and C 2n+1Hx (x⌾2), called polyhedral ions in this letter, have been found in hydrocarbon flames.
258 citations
TL;DR: In this article, maturation levels and kerogen types (which can be used to estimate the hydrocarbon generating potential of source rocks and oil shales) were defined by infrared spectroscopy.
250 citations
TL;DR: In this paper, the impact of non-methane hydrocarbons of natural and anthropogenic origin on the photochemistry of the nonurban lower atmosphere has been studied using a photochemical model with detailed planetary boundary layer transport.
Abstract: The impact of non-methane hydrocarbons of natural and anthropogenic origin on the photochemistry of the nonurban lower atmosphere has been studied using a photochemical model with detailed planetary boundary layer transport. The research was undertaken to evaluate the increase in peroxy radical concentrations due to hydrocarbon oxidation and their contribution to observed imbalances in the NOx, O3 photostationary state (Parrish et al., 1986a). The results show that these hydrocarbons, at concentrations observed in the atmosphere, reduce the hydroxyl radical concentration in clean air and increase the peroxy radical concentration to levels that are needed to explain the observed imbalance in the photostationary state. For the conditions simulated here, natural hydrocarbons are the principal contributors to the increase in the peroxy radical concentration at low NOx mixing ratios. At higher NOx levels the anthropogenic hydrocarbons that scale with NOx gain in importance. Model simulations that include the hydrocarbons reproduce the observed dependence of the concentration of ozone on various NOx concentrations.
241 citations
TL;DR: In this paper, the reactions of methanol, ethanol, 1-propanol, and 2-Propanol were examined on the clean Pd(111) surface using temperature programmed desorption (TPD).
239 citations
TL;DR: In this article, a series of monomeric and polymeric alkyl phases of different phase lengths were prepared by reaction with appropriate mono-and trichlorosilanes.
Abstract: A series of monomeric and polymeric alkyl phases of different phase lengths was prepared by reaction with appropriate mono- and trichlorosilanes. Selectivity changes with alkyl phase length were examined for phases ranging in length from C/sub 8/ to C/sub 30/. The retention behavior of polycyclic aromatic hydrocarbons (PAH) was observed to vary significantly with alkyl length. By use of PAH solute probes, phase selectivity of long-chain-length monomeric phases was found to approach that observed for C/sub 18/ polymeric phases. Retention behavior is discussed in terms of schematic representation of bonded phase behavior.
191 citations
TL;DR: In this paper, the ground electronic state of O(3P) atoms with unsaturated hydrocarbons was evaluated and conservative uncertainty limits assigned to the rate parameters of the reactions.
Abstract: Chemical kinetic data for reactions of O(3P) atoms with unsaturated hydrocarbons are compiled and critically evaluated. Specifically, the reactions considered include the interactions of the ground electronic state of oxygen atoms, O(3P), with alkenes, cycloalkenes, halogen substituted alkenes and ketenes, alkynes, halogen substituted alkynes, aromatic hydrocarbons, halogen substituted aromatic hydrocarbons and pyridine. All kinetic data considered were restricted to gas phase reactions. ‘‘Recommended’’ values of the rate parameters have been assessed and conservative uncertainty limits assigned to them.
183 citations
TL;DR: The reaction of chloro(5,10,15,20-tetramesitylporphinato)manganese(III) with m-chloroperoxybenzoic acid in CH2Cl2 containing methanolic (NMe4)OH at 0 °C yields the Mn(IV) complex (Ia) as mentioned in this paper.
Abstract: The reaction of chloro(5,10,15,20-tetramesitylporphinato)manganese(III) with m-chloroperoxybenzoic acid in CH2Cl2 containing methanolic (NMe4)OH at 0 °C yields the Mn(IV) complex (Ia).
TL;DR: In this paper, the initial products of the tropospheric oxidation of a representative mixture of hydrocarbons have been studied theoretically, using a detailed chemical mechanism involving 26 alkanes (C1-C8), alkenes (ethylene, propylene), aromatic hydro-carbons (benzene, toluene, o-, m-, and p-xylenes), and two terpenes (isoprene, α-pinene).
Abstract: The initial products of the tropospheric oxidation of a representative mixture of hydrocarbons have been studied theoretically, using a detailed chemical mechanism involving 26 alkanes (C1–C8), alkenes (ethylene, propylene), aromatic hydrocarbons (benzene, toluene, o-, m-, and p-xylenes), and two terpenes (isoprene, α-pinene). For an NOx-rich atmosphere the oxidation of the alkanes in the mixture leads to three main classes of initial products: aldehydes (34%), ketones (45%), and alkyl nitrates (21%). Both the γ-hydroxy-aldehydes (19%) and the γ-hydroxy-ketones (19% of all alkane initial products) are major products. For NOx-free conditions the major products of the alkane oxidation are expected to be the alkyl hydroperoxides. For NOx-rich conditions the aldehydes dominate the alkene oxidation products (80%), with smaller amounts of α-hydroxy-carbonyl compounds (9%) and organic acids (4%). The major products of the aromatic hydrocarbons in the mixture are α-dicarbonyls (24%), unsaturated γ- dicarbonyls (22%), phenols (<49%), aromatic aldehydes (3%), and aromatic nitrates (2%). The expected product distribution and lifetime data suggest that each class of hydrocarbon has certain unique products which should serve as useful indicators of the history of an aged air mass. It is concluded that the alkyl nitrates and the γ-hydroxy-alkyl nitrates may contribute to the large, and as yet unidentified, fraction of the active nitrogen species noted in NOy determinations in the troposphere by Fahey et al. (1986).
TL;DR: In this article, the effect of coal rank on the product distribution pattern was investigated in Ar at 1037 K with a Curie-point pyrolyser, using seventeen coals ranging from lignite to anthracite.
TL;DR: There are probably very few other systems in industrial chemistry which equal the CO/H2 reaction system in the variety of possible products as mentioned in this paper, and the fundamental knowledge on the reactions mentioned follows just the reverse order: I > II > III.
Abstract: There are probably very few other systems in industrial chemistry which equal the CO/H2 reaction system in the variety of possible products. When using pure Ni or Co catalysts one can produce almost pure CH, or a mixture of saturated hydrocarbons; a promoted (K2O) iron catalyst produces, in addition to these products, also alcohols, aldehydes, and other oxygen-containing products (oxygenates); and almost pure CH3OH can be obtained when applying Cu/ZnO/Al2O3 or Pd-MgO promoted SiO2 catalysts. Some catalysts (Rh/V2O3) can lead the reaction of syngas toward C2-oxygenates, and others to a mixture of C2+-alcohols and aldehydes (Co, K, Cr, Fe multicomponent catalysts). All this is schematically shown in Fig. 1. It is a remarkable, but not unusual, situation that while the economic interest follows the order (Fig. 1) III > II > I, the fundamental knowledge on the reactions mentioned follows just the reverse order: I > II > III. Although the leading ideas for preparing selective catalysts are onIy slowly...
TL;DR: In this article, the p-Xylene, du methane and de l'adamantane en ester de methyl-4benzyle, methyle, and adamantyle-1 were oxydated with trifluoroacetique.
Abstract: Oxydation du p-Xylene, du methane et de l'adamantane en ester de methyl-4benzyle, methyle et adamantyle-1 de l'acide trifluoroacetique
TL;DR: In this paper, a computer model quantitatively accounts for the dependence of selectivity on conversion and pressure, showing that at low conversion selectivity increases with higher pressure, whereas at high conversion it decreases.
Abstract: Methane reacts with a mixed Mn-Mg oxide above 800 /sup 0/C to give higher hydrocarbons as well as CO/sub 2/. The selectivity to hydrocarbons decreases the increasing conversion. At low conversion selectivity increases with higher pressure, whereas at high conversion it decreases. Kinetics studies implicate a Rideal-type mechanism wherein methyl radicals are produced at the oxide surface and most of the subsequent hydrocarbon-forming chemistry takes place in the gas phase. A computer model quantitatively accounts for the dependence of selectivity on conversion and pressure.
TL;DR: The results are reasonably consistent with computer model simulations and indicate that the effect of regulating emissions of an organic on ambient ozone will depend not only on the organics reaction rate but also on its reaction mechanism and the conditions under which it is emitted.
Abstract: A series of environmental chamber experiments have been carried out to investigate the incremental reactivities of selected organics with respect to ozone formation in simulated photochemical smog systems. Varying amounts of a test organic were added to or subtracted from a standard four-hydrocarbon minisurrogate - NO/sub x/ - air mixture to determine, as a function of irradiation time, the resulting changes in the amount of ozone formed and NO consumed, relative to the amount of the organic added. The incremental reactivities of toluene, trans-2-butene, and propene decreased significantly with reaction time, with toluene ultimately becoming negatively reactive; n-butane, ethanol, and tert-butyl methyl ether were always positively reactive; and benzaldehyde was always negatively reactive. The results are reasonably consistent with computer model simulations and indicate that the effect of regulating emissions of an organic on ambient ozone will depend not only on the organics reaction rate but also on its reaction mechanism and the conditions under which it is emitted. 33 references, 8 figures, 3 tables.
Patent•
19 Oct 1987TL;DR: In this article, a method for synthesizing diamond is proposed, which comprises: (a) generating a plasma by electric discharge in a gas selected from the group consisting of a hydrocarbon gas, hydrogen gas, an inert gas and a mixture thereof, decomposing a carbon source by the plasma to form plasma gas containing carbon ions or carbon radicals, and effecting adiabatic expansion of the plasma gas to precipitate diamond.
Abstract: A method for synthesizing diamond, which comprises: (a) generating a plasma by electric discharge in a gas selected from the group consisting of a hydrocarbon gas, hydrogen gas, an inert gas and a mixture thereof, (b) decomposing a carbon source by the plasma to form plasma gas containing carbon ions or carbon radicals, (c) effecting adiabatic expansion of the plasma gas to precipitate diamond.
Patent•
08 Oct 1987TL;DR: In this article, a selective adsorption system is employed for the recovery of methane and carbon dioxide from landfill gas (LFG) having a pretreat section operated in temperature swing adaption mode (TSA) to remove water and trace hydrocarbon contaminants, in flow communication with a pressure swing advertisersorption section (PSA) for separation of the methane from CO 2 contained in the purified gas stream discharged from the pretreat.
Abstract: In the recovery of methane and carbon dioxide from landfill gas (LFG) a selective adsorption system is employed having a pretreat section operated in temperature swing adsorption mode (TSA) to remove water and trace hydrocarbon contaminants, in flow communication with a pressure swing adsorption section (PSA) for separation of the methane from CO 2 contained in the purified gas stream discharged from the pretreat section. The LFG is introduced into a column in the TSA section and passed consecutively through a layer of activated carbon followed by a layer of solid desiccant such as a molecular sieve zeolite. The activated carbon layer adsorbs trace contaminants such as hydrocarbons and halohydrocabons boiling above methane; the zeolite layer adsorbs water. Regeneration of the adsorbent layers is carried out by flowing hot regeneration gas first through the zeolite layer then into and through the carbon layer. When the zeolite layer has been heated to the highest regeneration temperature by the regeneration gas, the inlet temperature of the gas is lowered by 100 or more degrees (°F), so that the carbon layer is regenerated at a lower temperature level to avoid detriment to the activated carbon adsorbent that might otherwise occur.
TL;DR: Experimental vapor-liquid equilibrium phase compositions, phase densities, and interfacial tensions are presented for CO/sub 2/ + cyclohexane and for CO 2 + benzene at 160/sup 0/F at pressures from 1000 psia to the critical point (interfacial tensions as low as 0.009 mN/M) as mentioned in this paper.
Abstract: Experimental vapor-liquid equilibrium phase compositions, phase densities, and interfacial tensions are presented for CO/sub 2/ + cyclohexane and for CO/sub 2/ + benzene at 160/sup 0/F at pressures from 1000 psia to the critical point (interfacial tensions as low as 0.009 mN/M). These data for CO/sub 2/ with a naphthenic and an aromatic hydrocarbon complement the authors' earlier work on binary mixtures of CO/sub 2/ with the paraffins n-butane and n-decane.
TL;DR: In this article, the structure of the Pt(III)-(2√3×4)rect-2C 6 H 6 +4CO coadsorption system has been analyzed with dynamical calculations of low-energy electron diffraction intensities.
TL;DR: In this paper, it is shown that the crucial first step in the mechanism is the formation of a surface methoxyl species which is primarily responsible for CH4 formation at low conversions.
Abstract: The mechanism of hydrocarbon formation from methanol has been studied by reacting methylating agents MeX (X = OH, I, OSO3Me) over the acidic form of the pentasil zeolite ZSM-5 and the sodium form of its conjugate base. At >0.1% conversions the product distributions obtained are similar, indicating that similar mechanisms for carbon–carbon bond formation operate with the three reagents. Hydrocarbon formation (CH4 and C2H4) from Me2SO4 over Na-ZSM-5 was observed and is considered to be strong evidence against the involvement of dimethyloxonium methylide as an intermediate since such a species cannot be formed with this reactant under basic conditions. Further evidence against the involvement of a dimethyloxonium methylide is given using reactivity comparisons of oxygen and sulphur-containing reagents. MeI and Me2SO4 were found to be less reactive than MeOH and at low conversion the primary hydrocarbon products observed, CH4and C2H4, suggest that these are the primary products formed in methanol conversion. Under conditions where conversion increased with reaction time, the methane/alkenes ratio decreased markedly and this is considered to be inconsistent with a mechanism involving a surface carbene intermediate formed in a one-step process from the reagent MeX. Instead it is proposed that the crucial first step in the mechanism is the formation of a surface methoxyl species which is primarily responsible for CH4 formation at low conversions. Deprotonation of the surface methoxyl species generates a surface-bonded oxonium methylide which subsequently reacts to form the initial carbon–carbon bond. This mechanistic proposal is both consistent with and unifies the available experimental data obtained for this reaction to date.
TL;DR: In this article, the synthesis of hydrocarbons from carbon dioxide and hydrogen was studied under pressurized conditions using hybrid catalysts composed of methanol synthesis catalysts and a high-silica zeolite (DAY).
TL;DR: In this paper, a high volume sampling on filter and on XAD-2 resin from the air of a small industrial town in Finland was performed to reveal characteristic POM profiles for various emission sources.
TL;DR: In this paper, α-,β-, and γ-cyclodextrin(CyD) were determined in aqueous medium at 25°C in the presence of excess CyD: benzene, toluene, ethylbenze...
Abstract: Formation constants of the following aromatic hydrocarbons with α-,β-, and γ-cyclodextrin(CyD) were determined in aqueous medium at 25°C in the presence of excess CyD : benzene, toluene, ethylbenze...
TL;DR: The acid-catalyzed rearrangement of triterpenoid monoenes belonging to the hopane and migrated hopane series with sulfuric acid and boron trifluoride etherate was investigated in this paper.
Abstract: The acid-catalyzed rearrangement of triterpenoid monoenes belonging to the hopane and migrated hopane series with sulfuric acid and boron trifluoride etherate was investigated. By selecting the reaction conditions, a variety of the monoenes of these series, including three new compounds, 9βH-fern-7-ene (3c), 8βH-fern-9 (11) -ene (4b), and adian-5 (10) -ene (5b), were obtained. For comparison, oleanenes and migrated oleanenes were also subjected to the same reaction.