Formation Of Hydrocarbon Gases Research Articles

Comparative characterization of anaerobic oil oxidation processes by microbial communities of sediments from natural oil seeps in Lake Baikal (Gorevoy Utes, Bolshaya Zelenovskaya)

The comparative characterization of oil biodegradation processes under anaerobic conditions during the cultivation of microbial communitiesof sediments from two sites of oil seeps is given. The microbial community of sediments from the Bolshaya Zelenovskaya River oil seep, functioning under the conditions of long-term exposure to hydrocarbons, is focused more on the processes of anaerobic oxidation of oil in comparison with the microbial communities of sediments from the oil seep located near Cape Gorevoy Utes. This is evidenced by the high level of hydrocarbon biodegradation in both surface and deep sediments, regardless of the electron acceptors present in the medium. Oil degradation in enrichment cultures was accompanied by the formation of hydrocarbon gases (methane and ethane). The highest concentration of methane formed was found in the experiment with sediments from Cape Gorevoy Utes. Ethane generation, on the contrary, was more typical of the cultivation of communities from sediments of the Bolshaya Zelenovskaya River. Microbial communities functioning under anaerobic conditions in sediments at the sites of oil seeps are no less important in the processes of self-purification of the lake from oil “pollution” than aerobic microbial communities of the water column and surface sediments.

Deep-basin gas generation via organic–inorganic interactions: New insights from redox-controlled hydrothermal experiments at elevated temperature

Under hot, deep-basin conditions, hydrogen-to-carbon ratios of residual kerogen are low. Whether ubiquitous water in sedimentary environments contributes hydrogen directly to hydrocarbon gas formation through organic-inorganic interactions is, therefore, critical for natural gas generation. Accordingly, we conducted laboratory experiments on immature to overmature kerogens at 300–600°C and 700 bar to examine the chemical interactions between kerogens and fluid under varying redox states and hydrothermal conditions. Mineral buffers, comprised of magnetite-hematite, nickel‑nickel oxide, cobalt‑cobalt oxide, and molybdenum‑molybdenum trioxide, were added to the experiments to control the redox state of the fluid from geologically reasonable to generally excessive values. The kerogens and mineral buffers were spatially isolated using double-capsule techniques to prevent contact catalysis.Our results indicated that chemical interactions between kerogens and water depended strongly on the kerogen thermal maturity and fluid redox state. The chemical interactions of overmature kerogens with reducing water were stronger than those of immature kerogens, which could be ascribed to the weaker competitive transfer of hydrogen from organics to organics than from water to organics. Unexpectedly high amounts of hydrocarbon gas were generated by incorporating water-derived hydrogen in the pyrolysis of overmature kerogens, and the yields increased under low to high reducing fluid conditions for a given temperature. Along with the increasing thermal maturity, residual kerogen eventually became ineffective for hydrocarbon gas generation through reduction reactions. Demethylation, bridge bond cleavage reaction, aromatic structure ring opening reactions in residual kerogen and subsequent redox reaction of intermediate products with reducing fluids is evidenced as the possible reaction mechanisms. The produced hydrocarbon gas under fH2 level of oilfield water is characterized by high dryness (99 mol%) and more-enriched 13C in CH4 compared with precursors. Natural gas deep within the Sichuan and Appalachian basins with similar characteristics suggests that our simulated organic–inorganic interactions could occur widely under natural conditions. Consequently, a potentially prolific source of natural gas may be formed by the overmature source rocks in the deep basin and fluid redox should be considered for gas potential evaluation of overmature source rocks.

Dehydration Leads to Hydrocarbon Gas Formation in Thermal Degradation of Gas-Phase Polyalcohols

To understand the molecular mechanisms of hydrocarbon gas formation in biomass gasification, gasification of simple polyalcohols (glycerol, propylene glycol, and ethylene glycol) were studied at 400, 600, and 800 °C (residence times: 0.9–1.4 s) from the viewpoint of dehydration reactions that form aldehydes with various substituents as intermediates to produce hydrocarbon gases. The results were also compared with those of glyceraldehyde and dihydroxyacetone, which are reported to produce syngas (H2 and CO) selectively. All polyalcohols became reactive at 600 °C to form condensable products in 15.7–24.7% yields (C-based), corresponding to 33.9–38.4% based on the amounts of reacted polyalcohols. These condensable products, mostly aldehydes, act as gas-forming intermediates, because the polyalcohols were completely gasified at 800 °C (hydrocarbon gas contents: 20.3–35.3%, C-based). Yields of the intermediates bearing alkyl groups at 600 °C were proportionally correlated to the yields of hydrocarbon gases at 800 °C, suggesting that the alkyl groups are further converted into hydrocarbon gases via the fragmentation of acyl radicals. Dehydration reactions were suggested to occur in both heterolytic and radical mechanisms by theoretical calculations. Glyceraldehyde tended to fragment directly into CO and H2, instead of forming a dehydration intermediate. These results are informative for controlling the product gas composition in biomass gasification.

Hydrocarbon gas generation by biochemical process of moderately barophilic methanogens in Barapukuria coal mine gas reservoir & aquifer

The research reported the biogenesis of hydrocarbon gases form the bituminous coal by moderately barophilic methanogens of coal mine water adjacent to underground aquifer and gas reservoir site of Barapukuria coal basin. Physiochemical characteristics of the coal (with zero gas baseline) as carbon source (Seam VI, 390m depth) for methanogens are determined. Parameters include inherent moisture content, volatile matter, ash content, calorific value, fixed carbon, α factor, H/C ratio, CHNSO elemental composition analysis, spectral assignments of ATR-FTIR, aromaticity factor fa and degree of aromatic ring condensation (R/C)u. Heavy, minors & light elements of calcined coal are also determined by X-ray fluorescence. Moderately barophilic methanogens surviving 5.61–6.45MPa lithostatic pressure (taking Barapukuria coal average specific gravity 1.43) are identified by fluorescence at ultraviolet region (100–400nm) of electromagnetic radiation and AQG-1 Methanometer. Bluish white fluorescence at UV is due to the redox coenzyme F350 in methanogens. Fluorescence at 350nm excitation is bluish white. The methanogens only have the ability to produce gas in presence of coal which acts as an electrode surface to take up electron for hydrogenase and other enzymes for formation of hydrocarbon gases. They also have the coal biodegradability. The methanogens yielded methane, ethylene, ethane, propane, iso-butane as detected by flame ionization detector of Bruker 450 gas chromatograph.

Molecular-mass distribution of saturated hydrocarbons in gas of the Lovozerskii nepheline-syenite massif

Specific features of the molecular-mass distribution of gaseous alkanes in the rocks of Lovozerskii alkaline massif, in particular, increase of the weight while temperature lowing during evolution of magmatic system and relatively higher contents of butanes, bearing in mind other geochemical and mineralogical data, indicate the possibility of hydrocarbon gas formation according to the Fisher-Tropsh type mechanism, which could be part of a more complicated multistage process, including oxidation and dehydrogenization reactions, heterogenic-catalytic polymerization, and condensation of hydrocarbons.

Molar Kinetics and Selectivity in Cracking of Athabasca Asphaltenes

The thermal decomposition of Athabasca bitumen asphaltenes was investigated in the temperature range 350 to 430 °C. The cracking kinetics of the asphaltenes and their intermediates were analyzed on a total a molar basis, to avoid the assumptions inherent in lumped kinetic models. The apparent first-order activation energy was 176 kJ/mol over the temperature range. Reaction selectivity changed from evolution of hydrogen sulfide to evolution of hydrocarbon gases and liquids over the same range of temperature. This change was consistent with a shift of the controlling reaction mechanism from the cleavage of C−S bonds to the cleavage of C−C bonds as temperature increased past 400 °C. The formation of hydrocarbon gases was the dominant reaction on a molar basis at temperatures over 400 °C, therefore, these reactions require more attention in mechanistic models for cracking of heavy petroleum fractions.

石炭液化反応における鉄触媒の低温活性発現機構

Transformation of iron based catalysts (γ-FeOOH α-FeOOH and natural pyrite) to pyrrhotite (Fe1-xS) was investigated in relation to the catalytic activ-ity in the initial stage of direct liquefaction of brown coal.XRD analysis indicated that γ-FeOOH could be completely transformed to pyrrho-tite with smaller crystallite size at 250°C, while only a part of pyrite converted at 350°C with a large crystal growth of pyrrhotite. It was found that remarkable hydrogen con-sumption was observed on the heating to 450°C during the liquefaction of Yallourn coal with γ-FeOOH compared to pyrite catalyst. Results from the analysis in the products suggested that gaseous hydrogen could be activated on Fe1-xS surface, followed by trans-fer to radical fragments produced through the thermal decomposition of coal.It was ascertained that γ-FeOOH had a excellent catalytic activity for hydrogen transfer to radical fragments in the initial stage during the liquefaction of brown coal be-cause of its lower transformation temperature to fine crystallite size pyrrhotite with high surface area, resulted in the higher oil yield with lower hydrogen consumption due to the less formation of hydrocarbon gases.

Liver hyperthermia and oxidative stress: role of iron and aldehyde production

Hyperthermia has been used to treat cancer in the liver. However, significant hepatotoxicity occurs at a therapeutic temperature of 42-43°C. We have proposed that heat toxicity is the result of oxidative stress from superoxide generation with resultant lipid peroxidation. Further, iron release from liver iron stores (ferritin) appears to play a central role in hyperthermic toxicity. In this study, rat livers were perfused in situ at 37 or 42°5°C with and without deferoxamine for 1 h with an asanguinous perfusate. Oxidative stress was assessed by the efflux of glutathione (GSH) into the perfusage. Prior studies by Skibba et al. (1989a, 1991) showed that perfusage equivalents of GSH were primarily present as oxidized glutathione (GSSG). Lipid peroxidation was assessed by the measurement of aldehydes appearing in the perfusate and formation of hydrocarbon gases (ethane and pentane) in the perfusion chamber head space. Liver injury was assessed by the leakage of cytosolic enzymes, AST and LDH, into the perfusate. Livers perfused at 42°5°C showed significant rises (p < 0°05) in AST and LDH after 60 min of perfusion but perfusion at 42°5°C with deferoxamine added, was not significantly different from perfusion at 37°C. Perfusion at 42°5°C caused an increase in GSH into the perfusate at a level significantly (p < 0°05) greater than at 37°C. GSH levels in the liver after 60 min of perfusion decreased from 4°82 ° 0°76 μM/gm at 37°C to 1°48°0°54μM/gm at 425°C (p < 0°05) but only fell to 3°42 ° 1°23 μM/gm at 42°5°C with deferoxamine added. Efflux of iron into the perfusate increase significantly with time and temperature. Low molecular weight chelated iron within the liver after perfusion increased from 5°88 ° 1°46 nM/gm at 37°C to 25°8 nM/gm at 42°5°C (p < 0°05). Perfusate total aldehyde levels increased from 0°085 ° 0°056 to 0°32 ° 0°09 μM/ml after 60 min at 37°C and 0°87 ° 0°45 to 201 ° 0°90 μM/ml at 42°5°C (n = 8). There was a significant decrease in total aldehyde levels at 42°5°C with the addition of deferoxamine to the perfusate, 0°36 ° 0°14 to 0°86 ° 0°27 μM/ml, when compared to 42°5°C levels (p < 0°05). Levels of ethane and pentane in the perfusion chamber head space showed no significnt changes with time or temperature of perfusion. The data suggest that lipid peroxidation may play a causal role in hyperthermia induced liver toxicity and that iron plays a major role in this injury. Failure of hydrocarbon analysis to support this conclusion appears related to the use of membrane oxygenators.

Hydrogen in petroleum geochemistry

ABSTRACT950 samples were analysed to study the possibility of using information on hydrogen in the evaluation of regional, zonal and local hydrocarbon potential. The main method for identifying that hydrogen is of natural origin is by comparison with the δD of hydrogen of technical origin that is −792‰. As an added criterion for recognizing the origin of hydrogen in wells the investigation of changes in gas composition within the borehole section is proposed. The distribution of hydrogen in the free and adsorbed states and the role of hydrogen in hydrocarbon gas formation have been evaluated. These data combined with tests on hydrogen absorption establish a difference between oil and gas generation in terrigenous and carbonate rocks caused by different types of organic matter and by the ability of hydrogen to be preserved in the crystal lattice of carbonate minerals. This absorbed hydrogen promotes HC generation and also changes the physical properties of limestones producing fundamentally different styles of fracture genesis.

EFFECT OF PREHYDROGENATION ON HYDROCONVERSION OF MAYA RESIDUUM, PART II: HYDROGEN INCORPORATION

Maya 650{sup 0}F residuum (Maya AR) was prehydrogenated over a standard hydroprocessing catalyst. The 650{sup 0}F residuum of this product (HMaya AR) and Maya AR were then separately hydroprocessed further at selected conditions. The products were examined by elemental, {sup 1}H and {sup 13}C NMR analyses to determine the how hydrogen was incorporated during processing. For all processing steps, hydrogen was incorporated in capping fragments formed during cracking reactions, as well as in hydrogenation reactions, heteroatom removal, and hydrocarbon gas formation, but the distribution of the hydrogen was dependent upon the type and severity of the process. For the direct hydroconversion of Maya AR, 25 to 30% of the total hydrogen was incorporated for heteroatom removal and hydrocarbon gas formation. The remaining hydrogen was incorporated in hydrogenation and cracking reactions. The hydrogen incorporation during each specific processing step is discussed, along with an evaluation of the prehydrogenation step as a residuum conversion process option. These results are compared to previously reported hydrogen incorporation measurements on other feeds and processing methods.

Production of ethane by rats treated with the colon carcinogen, 1,2-dimethylhydrazine

Ethane was exhaled by rats treated with the colon carcinogen, 1,2-dimethylhydrazine (DMH). At 1 hr, ethane production (mean ± SD) was 0.2 ± 0.2 nmol/ kg (controls) and 5.2 ± 1.3, 13.7 ± 3.4, and 27.7 ± 9.6, respectively, for DMH injections of 0.15 mmol/kg (20 mg/kg of the dihydrochloride salt), 0.45 mmol/kg, and 1.35 mmol/kg. Rates of ethane evolution tapered off after 2hr, but persisted for up to 3 hr at the lower dose, and up to 5–6 hr at the higher dose. Although ethane is produced in vivo during lipid peroxidation, experiments with vitamin E, a potent lipid antioxidant, indicated that lipid peroxidation was unlikely to be the source of ethane in DMH-treated rats: pretreatment with vitamin E had no effect on ethane formation from DMH but did suppress ethane production from rats treated with carbon tetrachloride, an inducer of hepatic lipid peroxidation. When rats were injected with 1,2-diethylhydrazine in place of DMH, large amounts of ethane and ethylene were produced (9800 and 5600 nmol/kg/hr). The hydrocarbon gases exhaled by rats may arise from dimerization of methyl radicals (· CH 3) generated during the metabolism of DMH, and from ethyl radicals (· CH 2CH 3) generated during the metabolism of 1,2-diethylhydrazine. Previously, it was shown that methane and ethane are formed from methyl radicals in vitro. Other investigators have observed formation of hydrocarbon gases during the in vitro metabolism of monoalkylhydrazines by microsomes, and ethyl radicals, derived from monoethylhydrazine, have been detected by electron spin-resonance spectroscopy. The results presented here suggest that in vivo metabolism of DMH may produce methyl radicals. Methyl radicals are capable of interacting with biomolecules. Their indiscriminate reaction with tissue constituents may be a contributory factor in DMH-induced carcinogenesis.

An XPS investigation of the interaction of CH 4, C 2H 2, C 2H 4 and C 2H 6 with a barium surface

The generation and pumping of hydrocarbon gases by a barium getter layer in electronic vacuum devices has been investigated by characterizing a barium film in an ultra high vacuum equipment by means of XPS before, during and after exposures to respectively CH 4, C 2H 2, C 2H 4 and C 2H 6. The reaction conditions (temperatures and pretreatment of the surface, background pressure and exposure doses) closely resemble those in electronic vacuum devices. The probability that a barium layer will react with CH 4 and C 2H 6 was below the detection limit. C 2H 2 and C 2H 4 give rise to the formation of barium carbide compounds and with a high reaction probability. In addition, the interaction with C 2H 2 reveals the formation of carbon-containing surface complexes. Investigations by means of XPS on the C Is spectral features show the presence of at least two groups of carbon-containing surface complexes, which behave differently in response to moderate heating and to an exposure to water vapour. In cases where oxygen is present at the surface, oxygen-containing (hydro) carbon adsorbates are present too. XPS observations of the behaviour of these surface complexes show similarities with reaction steps in the mechanisms proposed for the hydrogenation of CO in the Fischer-Tropsch synthesis of hydrocarbons. Low-pressure hydrogenation of these adsorbates containing hydrocarbons and oxygen can led to the formation of hydrocarbon gases in electronic vacuum devices.

Volatiles associated with alkaline igneous rift activity: Fluid inclusions in the Ilímaussaq intrusion and the Gardar granitic complexes (south Greenland)

Fluid inclusions in minerals from Si-oversaturated and Si-undersaturated alkalic igneous complexes belonging to the Precambrian Gardar Rift Province in South Greenland contain distinctly different carbon-bearing gases: granites and quartz syenites are characterized by CO 2 and only minor CH 4 whereas agpaitic nepheline syenites are dominated by hydrocarbons (essentially CH 4) and contain only insignificant amounts of CO 2 and/or CO. In the alkaline Ilímaussaq Intrusion the hydrocarbon-rich gases may well reflect equilibration with graphite at magmatic temperatures and at oxygen fugacities approaching those defined by the synthetic MW buffer reaction. In general, formation of hydrocarbon gases in agpaitic nepheline syenites is considered to reflect the fulfillment of three basic conditions: (1) low oxygen fugacities; (2) a wide temperature range of crystallization and a low-temperature solidus; and (3) retention of volatiles during crystallization. The characteristic carbon-bearing vapour associated with continental alkaline igneous activity is, however, considered to be CO 2.

Hydrocarbon gases produced during in vitro peroxidation of polyunsaturated fatty acids and decomposition of preformed hydroperoxides.

Hydrocarbon gases have been used previously as an index of lipid peroxidation in vivo and in vitro. In vitro experiments are reported on the formation of hydrocarbon gases from peroxidizing omega-3 and omega-6 fatty acids. Hydrocarbon gases were not released during a 20-hr peroxidation phase but were released following the decomposition of hydroperoxides by addition of excess ascorbic acid. The major hydrocarbon gas products in iron, copper, or hematin catalyzed peroxidation systems were ethane or ethylene from linolenic acid, and pentane from linoleic acid and arachidonic acid. Calculations of the ratios of hydrocarbon gases formed were based on fatty acid decrease and/or change in diene conjugation and peroxide values. Depending on the fatty acid, catalyst, and calculation basis used, pentane formation was as high as 1.3 mol %, ethane 4.3 mol %, and ethylene 10.6 mol %.