Showing papers on "Hydrocarbon published in 1992"

Transformation of Lower Alkanes into Aromatic Hydrocarbons over ZSM-5 Zeolites

Abstract: Much attention has been paid to the transformation of lower alkanes such as propane and butanes into aromatic hydrocarbons from both industrial and academic points of view The aromatic hydrocarbons can be utilized as a booster for high octane number gasoline and are fundamental raw chemicals in petroleum chemistry The activation of lower alkanes is an intriguing subject In early work, Csicsery [1–5] described dehydrocyclodimerization of lower alkanes over bifunctional catalysts such as platinum on alumina and Cr2O3 on alumina

Thermodynamic properties and dissociation characteristics of methane and propane hydrates in 70-.ANG.-radius silica gel pores

Abstract: The pressure-temperature profiles for the hydrate-ice-gas and hydrate-liquid water-gas equilibria were measured for methane and propane hydrates in 70-{Angstrom}-radius silica gel pores In both cases, the equilibrium pressures were 20-100% higher than those for the bulk hydrates The dissociation characteristics of the gas hydrates in pores were also studied calorimetrically by heating the hydrates under about zero pressure from 100 K to room temperature It was found that after the initial dissociation into ice and gas the hydrate became totally encapsulated among the pore walls and the ice caps formed at the pore openings The hydrate thus trapped in the interior of the pore remained stable up to the melting point of pore ice These results are similar to those obtained in previous studies on the bulk hydrates which are also stabilized by a shielding layer of ice However, the apparent increase in the stability of the pore hydrates was found to be much larger than that of the bulk hydrates The composition of methane hydrate in 70-{Angstrom} pores was determined to be CH{sub 4}{center_dot}594H{sub 2}O, and its heat of dissociation into pore water and gas, obtained calorimetrically, was 4592 kJ mol{sup {minus}1}; The corresponding values in the bulk phasemore » are 600 and 5419 kJ mol{sup {minus}1}, respectively 30 refs, 4 figs, 2 tabs« less

Partitioning of polycyclic aromatic hydrocarbons from diesel fuel into water

Abstract: An experimental evaluation of a model derived using Raoult's law convention for activity coefficients and hypothetical supercooled liquid solubilities is presented for the partitioning of eight polycyclic aromatic hydrocarbons (PAHs), all solids in their standard state, between fourdiesel fuels and water. The UNIFAC (UNIQUAC functional group activity coefficient) model was used to calculate the likely nonidealities resulting from infractionsbeen components in the diesel fuel

Electroosomotic Removal of Gasoline Hydrocarbons and TCE From Clay

Abstract: This laboratory study examines the application of electroosmosis (EO) for removal of hydrocarbons from clay. EO mobilization is conducted in 7.62‐cm inside diameter (id) glass columns containing 30.48 cm of clay and tap water electrolyte. Iron electrodes are used to impress a 0.4‐volt/cm DC electrical gradient. Destructive sampling of columns following various periods of EO treatment results in breakthrough curves describing relative hydrocarbon contaminant mobilization. EO flushing of dissolved organic chemicals in fine‐grained soils can be predicted using traditional contaminant‐transport equations, which incorporate advection, dispersion, and adsorption. Chemicals with relatively high water solubilities and low distribution coefficients (i.e., benzene, toluene, trichloroethylene (TCE), and m‐xylene) are easily removed from Kaolin by EO. Chemicals with a low water solubility and high distribution coefficient (i.e., hexane and isooctane) are transported from the clay at a slower rate. EO has the potentia...

Petroleum bioremediation — a multiphase problem

Abstract: Microbial degradation of hydrocarbons is a multiphase reaction, involving oxygen gas, water-insoluble hydrocarbons, water, dissolved salts and microorganisms. The fact that the first step in hydrocarbon catabolism involves a membrane-bound oxygenase makes it essential for microorganisms to come into direct contact with the hydrocarbon substrate. Growth then proceeds on the hydrocarbon/water interface. Bacteria have developed two general strategies for enhancing contact with water-insoluble hydrocarbons: specific adhesion mechanisms and production of extracellular emulsifying agents. Since petroleum is a complex mixture of many different classes of hydrocarbons, of which any particular microorganism has the potential to degrade only part, it follows that the microorganisms must also have a mechanism for desorbing from used' oil droplets.

Coadsorption of hydrocarbons and water on BPL activated carbon

Abstract: A novel experimental apparatus is used to measure hexane, acetone, water, hexane/water, and acetone/water isotherms on BPL activated carbon. Isotherms for pure components are measured from 25 to 125°C with hydrocarbon pressures varied by a factor of 10 7 , from low values to saturation. Emphasis is placed on measuring the hysteresis loop in the water and hydrocarbon/water systems. For adsorption of pure water, the location and size of the hysteresis loop is found to be temperature dependent, with the loop shifting toward higher relative pressures and narrowing as temperature is increased. For the hydrocarbon/water mixtures, the hydrocarbon loading is held constant and water isotherms are measured at 25 and 100°C. The partial pressure of the hydrocarbon is found to increase dramatically at constant hydrocarbon loading as the water loading is increased. Also, hysteresis is observed in the hydrocarbon partial pressure depending on whether the system is on the adsorption or desorption branch of the water isotherms. Behavior is complex and is interpreted qualitatively

Direct catalytic hydrodechlorination of toxic organics in wastewater

Abstract: The in-situ catalytic hydrodechlorination of chlorinated hydrocarbons in waste-water-generating HCl and a hydrocarbon-free chlorine is demonstrated as a viable wastewater remediation technique. Catalyst screening studies with a shaker-type hydrogenation reactor have shown that the commercial Pd/C catalyst is highly effective in hydrochlorinating various chlorinated hydrocarbons in synthetic wastewater at room temperature and near atmospheric pressure. 1, 1, 2-trichloroethane hydrodechlorination experiments in an autoclave reactor shows that initial rates are well correlated with first-order dependence of the reactant hydrocarbon adsorbed on carbon. Initial rates are also independent of hydrogen pressure, and adsorption on the carbon support is Langmuir type. Activation energies calculated at different catalyst loadings varied from 29 to 38 MJ/mol. 1,1,2-trichloroethane hydrodechlorination activity is much lower for Pd/Al2O3 than Pd/C because the reactant hydrocarbon does not adsorb on alumina. When the carbon support does not readily adsorb the reactant hydrocarbon, the hydrodechlorination rates dropped significantly. These results confirm the role of the carbon support in providing the major path to reaction and thereby significantly increasing reaction rates compared to direct adsorption from solution onto the palladium.

Supercritical carbon dioxide as reaction medium : examination of its solvent effects in the near-critical region

Abstract: The consequence of the compressible properties of supercritical carbon dioxide on the Diels-Alder reaction between isoprene and methyl acrylate in the solvent is discussed on the basis of IR spectroscopic data. The transition activation volume of the reaction and the excess number of solvent molecules about the reacting species have been thermodynamically determined using the ET(30) value of supercritical carbon dioxide. They are significantly changed with density in the near-critical region, where the activation volume gets greatest negative and the excess number of solvent molecules are greatly increased

Simulation of the solvation free energies for methane, ethane, and propane and corresponding amino acid dipeptides : a critical test of the bond-PMF correction, a new set of hydrocarbon parameters, and the gas phase-water hydrophobicity scale

Abstract: We have carried out free energy perturbation calculations to determine the relative free energies of solvation in water for methane, ethane, and propane. Experimentally, the relative solvation free energy of methane and ethane is -0.16±0.01 kcal/mol, and the relative solvation free energy of ethane and propane is 0.17±0.04 kcal/mol

Hydroformylation process and bisphosphite compound used therein

Abstract: A hydroformylation process for preparing a hydroformylated product by reacting an olefinic compound with hydrogen and carbon monoxide in the presence of a Group VIII metal catalyst, in the reaction of which there is present a phosphite compound having the formula (I), A¹⁅O-P(OR¹)(OR²)]n (I) wherein R¹ and R² are respectively an aromatic hydrocarbon group which may be the same or different and the aromatic hydrocarbon group has at least a hydrocarbon group on a carbon atom adjacent to a carbon atom bonded with an oxygen atom as a substituent; A¹ is an n-valent organic group having an aliphatic hydrocarbon group, a cycloaliphatic hydrocarbon group or an aromatic hydrocarbon group bonded with an adjacent oxygen atom, which may respectively have a substituent; n is an integer of from 2 to 4; and the respective ⁅O-P(OR¹)(OR²)] group may be the same or different.

Use of carbon adsorption traps combined with high resolution gas chromatography – mass spectrometry for the analysis of polar and non-polar C4-C14 hydrocarbons involved in photochemical smog formation

Abstract: A method has been developed for the collection and analysis of polar and non-polar C4-C14 hydrocarbons involved in the formation of photochemical smog. Enrichment of hydrocarbons from both polluted and unpolluted areas has been achieved with three-stage traps packed with carbon adsorbents of different surface area; the use of a home-made desorption unit employing cryofocusing then enables the determination of the compounds by HRGC-FID. Two-stage traps filled with graphitic carbon have been used prior to GC-MS identification and quantitation of compounds producing overlapping peaks. The methodology has been tested in the urban area of Rome and in a pine forest, and more than 140 different compounds identified and quantitated. Many of the constituents were found to be oxygenated, either formed by photochemical reactions or of anthropogenic origin.

The functionalization of saturated hydrocarbons. Part 20. Alkyl hydroperoxides: reaction intermediates in the oxidation of saturated hydrocarbons by Gif-type reactions and mechanistic studies on their formation

Abstract: Chemical and 13 C and 2 H NMR spectroscopic evidence is presented, proving that secondary alkyl hydroperoxides are reaction intermediates in the oxidation of saturated hydrocarbons under GoAgg II conditions (ferric chloride, hydrogen peroxide in pyridine-acetic acid solution)

Carbon-hydrogen activation in aqueous medium. The diverse roles of platinum(II) and metallic platinum in the catalytic and stoichiometric oxidative functionalization of organic substrates including alkanes

Abstract: The oxidation of ethers, alcohols, esters, and light alkanes (ethane, propanes) byu K 2 Pt/l 4 and Pt/O 2 in aqueous medium has been studied. Results appear to indicate that unactivated C-H bonds were attacked and oxidized by Pt(II) whereas C-H bonds α to an oxygen were activated and catalytically oxidated by metallic Pt in the presence of O 2 . For example, Pt(II) was found to oxidize ethane selectively to the alcohols, ethanol, and ethylene glycol. In the presence of metallic Pt and O 2 , further oxidation of the alcohol functionality occurred to generate the corresponding carboxylic acids

Hydrates of hydrocarbon gases containing carbon dioxide

Abstract: This work presents equilibrium measurements for hydrate three-phase (vapor-hydrate-aqueous liquid) behavior for natural gas components with high concentrations of carbon dioxide, at temperatures between the ice point and the quadruple point of each mixture. Binary hydrate phase equilibria were measured for carbon dioxide with each of the following gases: methane, ethane, propane, isobutane, and normal butane. Data for three of those binary systems (carbon dioxide+ethane, 2-methylpropane (isobutane), and butane) do not exist in the literature

Redox Reactions Involving Hydrocarbons and Mineral Oxidants: A Mechanism for Significant Porosity Enhancement in Sandstones

Abstract: Hydrocarbon invasion into a sandstone containing mineral oxidants and carbonate or sulfate intergranular cements may result in redox reactions and significantly enhanced porosity. For years, geologists have noted that when hydrocarbons invade red sandstones, significant bleaching (i.e., iron reduction) takes place. The reactions responsible for the color distribution in the red (oxidized) and white (reduced) zones are reactions of iron oxides (± sulfate) with hydrocarbons. The iron oxides (± sulfate) oxidize the hydrocarbons (reductant) to oxygenated organic compounds; the Fe2O3 (oxidant) is reduced by hydrocarbons to pyrite (± chlorite). Commonly, the red sandstones are tight due to carbonate and sulfate cements, whereas the white zones within them are more porous. These redox reactions are of three types: [EQUATION] or [EQUATION] or [EQUATION] The produced organic acids are available to dissolve carbonate cements via the reaction [Equation]. Volumetric calculations demonstrate that if a hematite-stained sandstone (1.5% Fe2O3) is invaded by a fluid containing a 50/50 mixture of water and hydrocarbons, and redox reactions result, enough organic acid and consequent carbonate dissolution could occur to generate 8-14% additional porosity. More subtle redox reactions involving hydrocarbons and mineral oxidants have the potential to significantly enhance porosity in any sandstone. These redox reactions may explain why hydrocarbon accumulations appear to have created porosity in some cases.

Methods for inhibiting polymerization of hydrocarbons utilizing a hydroxyalkylhydroxylamine

Abstract: The present invention pertains to methods and compositions for inhibiting polymerization of hydrocarbons during processing and storage. The methods comprise adding an effective amount of a hydroxyalkylhydroxylamine compound to the hydrocarbon sought to be treated.

A comparative study on the activation and reactions of CH4 on supported metals

Abstract: The catalytic effects of silica-supported Pt metals were tested and compared in the decomposition of methane and its conversion into higher hydrocarbons. The dissociation of methane is readily measurable at 473–673 K. The rate of initial decomposition at 523 K was the highest on Rh, but it dropped to a low value within a short contact time. The gaseous products were hydrogen and ethane in small, variable amounts. Hydrogen of the carbonaceous species formed in the decomposition led to the production of aliphatic hydrocarbons.

In situ solid-state NMR study of methanol-to-gasoline chemistry in zeolite HZSM-5

Abstract: This paper uses {sup 13}C solid-state NMR to study the chemistry of a variety of absorbates related to the methanol-to-gasoline process. This study has resulted in a better understanding of the chemical reaction occurring inside the zeolite HZSM-5 used in this process. It is shown that ethylene is the first olefin formed and ethyl methyl ether is also formed during this hydrocarbon synthesis on zeolite HZSM-5.

Methods and apparatus for determining hydrocarbon fuel properties

Abstract: Method and apparatus for monitoring hydrocarbon-based fuel properties by measuring the presence and amount of fuel component molecules in the fuel solution. Detection is made of absorption related to signature vibrational modes associated with the fuel component molecules when excited in the mid-IR. In one embodiment, a mid-IR light source illuminates the fuel in-situ and a narrow bandwidth detector associated with a vibrational mode signature detects absorbance as an indication of the presence and quantity of the fuel component in solution. From the determined fuel component quantity and known characteristics, the fuel solution properties are predicted. In one embodiment, octane rating and vapor pressure for a fuel solution is determined in-situ and in real time.