Showing papers on "Hydrocarbon published in 2001"

Innovation of Hydrocarbon Oxidation with Molecular Oxygen and Related Reactions

Abstract: An innovation of the aerobic oxidation of hydrocarbons through catalytic carbon radical generation under mild conditions was achieved by using N-hydroxyphthalimide (NHPI) as a key compound. Alkanes were successfully oxidized with O2 or air to valuable oxygen-containing compounds such as alcohols, ketones, and dicarboxylic acids by the combined catalytic system of NHPI and a transition metal such as Co or Mn. The NHPI-catalyzed oxidation of alkylbenzenes with dioxygen could be performed even under normal temperature and pressure of dioxygen. Xylenes and methylpyridines were also converted into phthalic acids and pyridinecarboxylic acids, respectively, in good yields. The present oxidation method was extended to the selective transformations of alcohols to carbonyl compounds and of alkynes to ynones. The epoxidation of alkenes using hydroperoxides or H2O2 generated in situ from hydrocarbons or alcohols and O 2 under the influence of the NHPI was demonstrated and seems to be a useful strategy for industrial applications. The NHPI method is applicable to a wide variety of organic syntheses via carbon radical intermediates. The catalytic carboxylation of alkanes was accomplished by the use of CO and O2 in the presence of NHPI. In addition, the reactions of alkanes with NO2 and SO2 catalyzed by NHPI provided efficient methods for the synthesis of nitroalkanes and sulfonic acids, respectively. A catalytic carbon-carbon bond forming reaction was achieved by allowing carbon radicals generated in situ from alkanes or alcohols to react with alkenes under mild conditions. 1 Introduction 2 Discovery of NHPI as Carbon Radical Producing Catalyst from Alkanes 2.1 Historical Background 2.2 Catalysis of NHPI in Aerobic Oxidation 3 NHPI-Catalyzed Aerobic Oxidation 3.1 Oxidation of Benzylic Compounds 3.2 Alkane Oxidations with Molecular Oxygen 3.3 Oxidation of Alkylbenzenes 3.4 Practical Oxidation of Methylpyridines 3.5 Preparation of Acetylenic Ketones via Alkyne Oxidation 3.6 Oxidation of Alcohols 3.7 Selective Oxidation of Sulfides to Sulfoxides 3.8 Production of Hydrogen Peroxide by Aerobic Oxidation of Alcohols 3.9 Epoxidation of Alkenes using Molecular Oxygen as Terminal Oxidant 4 Carboxylation of Alkanes with CO and O2 5 Utilization of NOx in Organic Synthesis 5.1 First Catalytic Nitration of Alkanes using NO2 5.2 Reaction of NO with Organic Compounds 6 Sulfoxidation of Alkanes Catalyzed by Vanadium 7 Carbon-Carbon Bond Forming Reaction via Catalytic Carbon Radicals Generated from Various Organic Compounds Assisted by NHPI 7.1 Oxyalkylation of Alkenes with Alkanes and Dioxygen 7.2 Synthesis of α-Hydroxy-γ-lactones by Addition of α-Hydroxy Carbon Radicals to Unsaturated Esters 7.3 Hydroxyacylation of Alkenes using 1,3-Dioxolanes and Dioxygen 8 Conclusions

Source apportionment of urban particulate aliphatic and polynuclear aromatic hydrocarbons (PAHs) using multivariate methods

Abstract: Samples of organic aerosol were collected in Santiago de Chile. An activated-charcoal diffusion denuder was used to strip out organic vapors prior to particle collection. Both polynuclear aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons were determined using gas chromatography/mass spectrometry (GC/MS). Organic particle sources were resolved using both concentration diagnostic ratios and multivariate methods such as hierarchical cluster analysis (HCA) and factor analysis (FA). Four factors were identified based on the loadings of PAHs and n-alkanes and were attributed to the following sources: (1) high-temperature combustion of fuels; (2) fugitive emissions from oil residues; (3) biogenic sources; and (4) unburned fuels. Multilinear regression (MLR) analysis was used to determine emission profiles and contributions of the sources. The reconstructed concentrations of particle phase aliphatic and polynuclear aromatic hydrocarbons were in good agreement (R2 > 0.70) with those measured in Santiago de Chile.

In situ thermal processing of a hydrocarbon containing formation to produce a hydrocarbon condensate

Abstract: A hydrocarbon containing formation may be treated using an in situ thermal process. Hydrocarbons, H 2 , and/or other formation fluids may be produced from the formation. Heat may be applied to the formation to raise a temperature of a portion of the formation to a pyrolysis temperature. Heat input into the formation may be controlled to raise a temperature of the formation at a selected rate.

Molecular sieve catalysts for the regioselective and shape- selective oxyfunctionalization of alkanes in air.

Abstract: Framework-substituted, molecular-sieve, aluminophosphate, microporous solids are the centerpieces of a new approach to the aerobic oxyfunctionalization of saturated hydrocarbons. The sieves, and the few percent of the AlIII sites within them that are replaced by catalytically active, transition-metal ions in high oxidation states (CoIII, MnIII, FeIII), are designed so as to allow free access of oxygen in to and out of the interior of these high-area solids. Certain metal-substituted, molecular sieves permit only end-on approach of linear alkanes to the active centers, thereby favoring enhanced reactivity of the terminal methyl groups. By optimizing cage dimension, with respect to that of the hydrocarbon reactant, as well as adjusting the average separation of active centers within a cage, and by choosing the sieve with the appropriate pore aperture, highly selective conversions such as n-hexane to hexanoic acid or adipic acid, and cyclohexane to cyclohexanol, cyclohexanone, or adipic acid, may be effected...

Thermodynamic Properties of Mixtures Containing Ionic Liquids. 1. Activity Coefficients at Infinite Dilution of Alkanes, Alkenes, and Alkylbenzenes in 4-Methyl-n-butylpyridinium Tetrafluoroborate Using Gas−Liquid Chromatography

Abstract: Activity coefficients at infinite dilution γi∞ of 19 alkanes, alkenes, and alkylbenzenes in the ionic liquid 4-methyl-n-butylpyridinium tetrafluoroborate (C10H16BF4N) were determined by gas chromatography using the ionic liquid as stationary phase. The measurements were carried out at different temperatures between 313.1 K and 363.1 K. From the temperature dependence of the limiting activity coefficients partial molar excess enthalpies at infinite dilution of the organic solutes in the ionic liquids have been derived.

Kinetics of CO2 Hydrogenation on a K-Promoted Fe Catalyst

Abstract: CO2 hydrogenation on a K-promoted Fe catalyst was studied in a fixed-bed microreactor between 300 and 400 °C, at 1 MPa, and with modified residence times in the range of 0.042−21.4 g·s/cm3. For temperatures below 360 °C, organic products almost identical with those found in the traditional Fischer−Tropsch reaction with H2/CO were found (paraffins and α-olefins). At 400 °C, formation of carbon deposited on the catalyst became a major reaction. Concerning the mechanism of hydrocarbon formation, the effect of residence time resulted in catalyst particle selectivity values for hydrocarbons always higher than zero. This indicates that, besides the two-step reaction mechanism via CO, a direct hydrocarbon formation from CO2 can occur in principle. With a reaction scheme proposed from these experimental results, a kinetic model was developed using integration and regression features of ASPEN PLUS. Calculated values for CO2 conversion and CO and total hydrocarbon selectivities agree with the experimental data with...

Methanol-to-hydrocarbons reaction over SAPO-34. Molecules confined in the catalyst cavities at short time on stream

Abstract: In order to obtain more insight into the methanol-to-hydrocarbons (MTH) reaction the organic molecules confined in a working SAPO-34 catalyst have been studied. The reaction was run for varying times, 30 s to 30 min. At a predetermined time the reaction was stopped and the catalyst dissolved in 1 M HCl. The gas phase above the solution as well as a CCl4 extract were analyzed by gas chromatography (MS detector). The gas phase consists mainly of isoalkanes C4–6. The less volatile organic molecules were concentrated in the CCl4 extract. More than 200 different species are present, but polymethylbenzenes, with one to six methyl groups, are always dominating. They constitute 30–50% of the samples. Penta- and hexamethylbenzene easily split off small hydrocarbons and turn into di- and trimethylbenzenes. It is speculated that methylations of arenes which thereupon split off small alkenes and then are remethylated again may be an essential part of the catalytic activity in the MTH reaction.

Engineering Cytochrome P450 BM-3 for Oxidation of Polycyclic Aromatic Hydrocarbons

Abstract: Cytochrome P450 BM-3, a self-sufficient P450 enzyme from Bacillus megaterium that catalyzes the subterminal hydroxylation of long-chain fatty acids, has been engineered into a catalyst for the oxidation of polycyclic aromatic hydrocarbons. The activities of a triplet mutant (A74G/F87V/L188Q) towards naphthalene, fluorene, acenaphthene, acenaphthylene, and 9-methylanthracene were 160, 53, 109, 287, and 22/min, respectively. Compared with the activities of the wild type towards these polycyclic aromatic hydrocarbons, those of the mutant were improved by up to 4 orders of magnitude. The coupling efficiencies of the mutant towards naphthalene, fluorene, acenaphthene, acenaphthylene, and 9-methylanthracene were 11, 26, 5.4, 15, and 3.2%, respectively, which were also improved several to hundreds fold. The high activities of the mutant towards polycyclic aromatic hydrocarbons indicate the potential of engineering P450 BM-3 for the biodegradation of these compounds in the environment.

Oxidations by the system “hydrogen peroxide–manganese(IV) complex–carboxylic acid”: Part 3. Oxygenation of ethane, higher alkanes, alcohols, olefins and sulfides

Abstract: The manganese(IV) complex salt [L2Mn2O3](PF6)2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) (compound 1, see Scheme 1) very efficiently catalyzes the hydroperoxidation of saturated hydrocarbons, including ethane by H2O2 in acetontitrile or nitromethane solution at low (room or lower) temperature, provided a carboxylic (typically acetic) acid is present. The hydroperoxidation of tertiary positions in disubstituted cyclohexanes proceeds with partial retention of configuration in nitromethane or acetonitrile solution, while the stereoselectivity of the reaction is only negligible in acetone solution. The system “H2O2–compound 1–MeCO2H” also transforms secondary alcohols into the corresponding ketones with quantitative yields at room temperature within a few minutes; the yields of aldehydes and carboxylic acids in the oxidation of primary alcohols are lower. Terminal aliphatic olefins such as hexene-1 are quantitatively epoxidized by the same system in acetonitrile at room temperature within 20 min, while the epoxide yield in the analogous reaction with styrene attains only 60% under the same conditions. Finally, dimethylsulfide can be quantitatively and selectively converted into dimethylsulfoxide within 3 h at room temperature. The system “tert-BuOOH–compound 1” also oxidizes alkanes, addition of acetic acids has less pronounced effect on the direction and efficiency of the reaction. Two other checked derivative of Mn(IV) (compounds 2 and 3) as well a porphyrin complex of Mn(III) (compound 4) exhibited lower activity in catalysis of alkane oxidation with tert-BuOOH. © 2001 Elsevier Science B.V. All rights reserved.

Hydrogen Production from Hydrocarbon by Integration of Water−Carbon Reaction and Carbon Dioxide Removal (HyPr−RING Method)

Abstract: A new hydrogen production method, HyPr−RING (Hydrogen Production by Reaction Integrated Novel Gasification), from organic compounds has been proposed. The fundamental concept of this process is integration of the water−hydrocarbon reaction, water-gas shift reaction, and the absorption of CO2 and other pollutants in a single reactor. Hydrogen productivity from the reactions of organic material(s) with supercritical water was investigated in ranges of pressure 12−105 MPa and temperature 873−973 K by using a micro-autoclave. CO2 was absorbed by a sorbent during the reactions in the micro-autoclave. It was found that H2 and CH4 as the major product gases can be produced from lignite, subbituminous, bituminous, and several organic wastes. For example, 170 cm3 of gas with about 80% H2 and 20% CH4 was produced from 0.1 g of the subbituminous Taiheiyo coal, at 923 K. In this case, about 90% of the carbon in the Taiheiyo coal was converted to produce H2 and CH4. Some organic materials including chlorine and sulfur...

Hydrogen production method

Abstract: A method of producing a hydrogen product stream in which a steam stream is reacted with a hydrocarbon containing stream within a steam methane reformer. The resulting product stream is subjected to a water gas shift reaction and then to pressure swing adsorption to produce the hydrogen product stream. The hydrocarbon stream is alternatively formed from a first type of feed stream made up of natural gas, refinery off-gas, naphtha or synthetic natural gas or combinations thereof and a second type that is additionally made up of a hydrogen and carbon monoxide containing gas. During use of both of the types of feed streams, the flow rate of the steam stream is not substantially changed and reformer exit temperatures of both the reactant and the flue gas side are held essentially constant.

Process for removing low amounts of organic sulfur from hydrocarbon fuels

Abstract: A process for desulfurizing fuels such as diesel oil and similar petroleum products to reduce the sulfur content to a range of from about 2 to 15 ppm sulfur is described. The sulfur containing fuel is contacted at slightly elevated temperatures with an oxidizing/extracting solution of formic acid, a small amount of hydrogen peroxide, and no more than about 25 wt % water. A removal process for separating substituted dibenzothiophene oxidation products from the fuel is also described.

A review of the neurotoxicity risk of selected hydrocarbon fuels.

Abstract: Over 1.3 million civilian and military personnel are occupationally exposed to hydrocarbon fuels, emphasizing gasoline, jet fuel, diesel fuel, or kerosene. These exposures may occur acutely or chronically to raw fuel, vapor, aerosol, or fuel combustion exhaust by dermal, respiratory inhalation, or oral ingestion routes, and commonly occur concurrently with exposure to other chemicals and stressors. Hydrocarbon fuels are complex mixtures of 150-260+ aliphatic and aromatic hydrocarbon compounds containing varying concentrations of potential neurotoxicants including benzene, n-hexane, toluene, xylenes, naphthalene, and certain n-C9-C12 fractions (n-propylbenzene, trimethylbenzene isomers). Due to their natural petroleum base, the chemical composition of different hydrocarbon fuels is not defined, and the fuels are classified according to broad performance criteria such as flash and boiling points, complicating toxicological comparisons. While hydrocarbon fuel exposures occur typically at concentrations below...

Catalytic properties of Co/Al2O3 system for hydrocarbon synthesis

Abstract: Co/Al2O3 catalysts, prepared from four commercial aluminas, with different cobalt loading have been studied for the carbon monoxide hydrogenation (Fischer–Tropsch synthesis). The effects of reaction and reduction temperatures, deactivation, cobalt content and texture of supports on the catalytic properties have been especially examined. An increase in the reaction temperature improves the activity and the selectivity for light products. The product distribution follows the Schulz–Flory model. For the 15 wt.% Co on powder alumina catalyst, the activity and the paraffin/olefin ratio C6−/C6 follow a logarithmic decrease with the time-on-stream. Characterization by XRD, XPS and SSA measurements have shown the presence of heavy hydrocarbons (C12+) in the tested catalyst porosity. The cobalt loading and the porosity of supports modify the catalytic properties through their effects on the reducibility of the active phase. An increase in the extent of reduction improves the activity and the selectivity for high molecular hydrocarbons weight. The evolution of the chain growth probability (α) is closely related to the degree of reduction. In the absence of secondary reactions, α seems to be limited at a maximum value.

Mixed hydrates of methane and water‐soluble hydrocarbons modeling of empirical results

Abstract: The hydrate disappearance conditions (H − Lw − V → Lw − V transition) in the water–methane–water-soluble hydrocarbon system were measured and modeled. The hydrocarbons in the experiments are tetrahydrofuran (THF), 1,3-dioxolane and tetrahydropyran, and THF, 1,3-dioxolane and acetone in the modeling study. Experiments and calculations, which correspond qualitatively and quantitatively very well, show a large reduction in the equilibrium pressure upon addition of the hydrocarbons. The minimum pressure is about 5–6 mol % hydrocarbon relative to water, independent of temperature and applied hydrocarbon, with the composition almost equal to the ratio between the number of large cages and water molecules in structure II hydrates (5.88%). Based on this observation, the hydrates are assumed to be structure II methane–hydrocarbon mixed hydrates. The model is also used to calculate the occupancies of the hydrate cavities. No experimental data are available to compare the predicted values, but the results help understand observed phenomena better.