Showing papers on "Methane published in 1974"

The Origin and Distribution of Methane in Marine Sediments

Abstract: Methane has been detected in several cores of rapidly deposited (> 50 m/my) deep sea sediments. Other gases, such as carbon dioxide and ethane, are commonly present but only in minor and trace amounts, respectively. The methane originates predominantly from bacterial reduction of CO2, as indicated by complimentary changes with depth in the amount and isotopic composition of redox-linked pore water constituents: sulfate-bicarbonate and bicarbonate-methane.

Methane production in the interstitial waters of sulfate-depleted marine sediments.

Abstract: Methane in the interstitial waters of anoxic Long Island Sound sediments does not reach appreciable concentrations until about 90 percent of seawater sulfate is removed by sulfate-reducing bacteria. This is in agreement with laboratory studies of anoxic marine sediments sealed in jars, which indicate that methane production does not occur until dissolved sulfate is totally exhausted. Upward diffusion of methane or its production in sulfate-free microenvironments, or both, can explain the observed coexistence of measurable concentrations of methane and sulfate in the upper portions of anoxic sediments.

Mechanisms of Oil Displacement By Carbon Dioxide

Abstract: CO/sub 2/ can enhance the recovery of oil from porous rock by (1) solution gas drive, (2) swelling oil and reducing its viscosity, and (3) miscible effects. The most efficient use of carbon dioxide as an oil recovery agent is obtained at flooding pressures where miscible type displacement is achieved.The extraction of hydrocarbons (C/sub 3/ to C/sub 30/) from the crude oil in place by CO/sub 2/ at these pressures promotes a displacement efficiency which approaches 100%. This high displacement efficiency can be obtained at flooding temperatures below 200/sup 0/F and pressures below 3,000 psi with any crude oil containing appreciable hydrocarbons in the gasoline-light gas-oil range. Also, the process is applicable to waterflooded reservoirs which have been depleted of their gas and LPG components. The presence of methane in the injected CO/sub 2/ or in the reservoir oil reduces the overall recovery efficiency of the displacement process. A simple correlation is presented to determine the optimum displacement pressure for CO/sub 2/ floods.

Natural Gases in Marine Sediments

Abstract: Pathways and Environmental Requirements for Biogenic Gas Production in the Ocean.- Depth Distributions of Gases in Shallow Water Sediments.- Methane and Carbon Dioxide in Coastal Marsh Sediments.- Hydrocarbon Gas (Methane) in Canned Deep Sea Drilling Project Core Samples.- Dissolved Gases in Cariaco Trench Sediments: Anaerobic Diagenesis.- Isotopic Analysis of Gas from the Cariaco Trench Sediments.- The Origin and Distribution of Methane in Marine Sediments.- Geothermal Gases.- The Nature and Occurrence of Clathrate Hydrates.- Review of Gas Hydrates with Implication for Ocean Sediments.- Occurrence of Natural Gas Hydrates in Sedimentary Basins.- Experiments on Hydrocarbon Gas Hydrates in Unconsolidated Sand.- Effects of Gas Hydrates in Sediments.- Acoustics and Gas in Sediments: Applied Research Laboratories (ARL) Experience.- Gas Bubbles and the Acoustically Impenetrable, or Turbid, Character of Some Estuarine Sediments.- In Situ Indications of Gas Hydrate.- Pagoda Structures in Marine Sediments.- List of Contributors.

Production of methane-rich gas

Abstract: This is an improved continuous process for producing a clean methane-rich gas stream without the concomitant formation of particulate carbon which would ordinarily decrease the efficiency of the process and shorten the life of the catalyst. By-product superheated steam is simultaneously produced at a maximum temperature. The product stream may have a methane content up to 98 to 99 mole % or higher and a gross heating value up to 1000 BTU per SCF or more. Process steps include partial oxidation of a hydrocarbonaceous fuel under operating conditions that produce a synthesis gas containing 10 to 30 mole % methane (dry and CO2free basis) and a H2/CO mole ratio of 2.6 or higher, and reacting the methane-rich process gas stream in one to three catalytic methanation stages under critical operating conditions that increase the methane content in the process gas stream stepwise up to 98 mole % or higher without incipient soot formation for each corresponding CH4 content of the feed as one proceeds from one methanation step to another. Heat from the highly exothermic methanation reaction is used to make valuable by-product superheated steam. The product gas may be burned without polluting the atmosphere.

Temperature effects on anaerobic fermentation of domestic refuse

Abstract: Anaerobic fermentation of organic solid waste can provide a significant source of fuel gas (methane). Application of this process requires a better understanding of the kinetics of the biological system. The literature is replete with kinetic studies of this process as applied to waste solids from water pollution control systems. Much of this work has been conducted in the mesophilic temperature range. Increased temperatures yield higher reaction rates that will improve the economics of the process. The rate limiting step in the fermentation of refuse is the hydrolysis of the complex organic solids, in particular cellulose. Cellulose is a major component of the refuse. A laboratory study employing domestic refuse has shown the effect of temperature on the rate of methane fermentation. The optimum mesophilic temperature was found to be 42°C, while the optimum thermophilic temperature was at least 60°C. No data was obtained beyond the 60°C temperature. Reaction rate constants are presented for anaerobic fermentation of domestic refuse. Because of the characteristics of the substrate it−was not possible to obtain the necessary measurements for evaluation of constants in the Monod model. An overall system constant was developed.

Interrelations between sulfate-reducing and methane-producing bacteria in bottom deposits of a fresh-water lake. I. Field observations

Abstract: Observations on the seasonal periodicity in bottom deposits of Lake Vechten indicated an ecological relationship between sulfate-reducing and methane-producing bacteria. Sulfate reducers are most abundant at depths of 0 to 2 cm in the mud at pS2- values of about 11 and redox potential values of-100 to-150 mV. Maximum number of methane producers are situated at depths of 3 to 6 cm in the mud at pS2- values of about 14, redox potential values of-250 to-300 mV and maximum values of the methane concentration.

Measurement of microbial oxidation of methane in lake water

Abstract: A radiotracer method which measures rates of oxidation of methane to cell material, extracellular products, and carbon dioxide has been applied to two lakes and indicates that methane oxidation occurred in a narrow band where methane and oxygen occurred together in the water column. Oxidation rates of 1.0 µM hr−1 were recorded in a eutrophic lake; rates in a meromictic lake reached 0.15 µM hr−1. Usually a third of the carbon from oxidized methane was found in cell material and extracellular products and the rest was converted to carbon dioxide. This ratio was observed to change at very low oxygen concentrations.

Isolation and Characterization of Bacteria That Grow on Methane and Organic Compounds as Sole Sources of Carbon and Energy

Abstract: Bacteria capable of growth on methane and a variety of complex organic substrates as sole sources of carbon and energy have been isolated Conditions used to rigorously establish the purity of the cultures are described One facultative methylotroph has been studied in detail This organism has peripherally arranged pairs of intracytoplasmic membranes characteristic of obligate methylotrophs This isolate apparently utilizes the serine pathway of formaldehyde fixation The location of methane oxidizers in a dimictic lake indicates that these organisms prefer less than saturating levels of dissolved oxygen Laboratory experiments confirmed the preference of these organisms for atmospheres containing less oxygen than air

Rapid method for the radioisotopic analysis of gaseous end products of anaerobic metabolism.

Abstract: A gas chromatographic procedure for the simultaneous analysis of 14C-labeled and unlabeled metabolic gases from microbial methanogenic systems is described. H2, CH4, and CO2 were separated within 2.5 min on a Carbosieve B column and were detected by thermal conductivity. Detector effluents were channeled into a gas proportional counter for measurement of radioactivity. This method was more rapid, sensitive, and convenient than gas chromatography-liquid scintillation techniques. The gas chromatography-gas proportional counting procedure was used to characterize the microbial decomposition of organic matter in anaerobic lake sediments and to monitor 14CH4 formation from H2 and 14CO2 by Methanosarcina barkeri.

Chemisorption and exchange with deuterium of methane on metals

Abstract: The interaction of methane with metal catalysts has received less attention than that of hydrocarbons containing two or more carbon atoms [1]. Yet methane is interesting because its electronic structure resembles that of a rare gas and it possesses high symmetry and small reactivity. Also, it is the most stable of the alkanes and one of the few thermodynamically stable at room temperature. The temperature at which methane should spontaneously decompose (δG° = 0) is 570°C [2] and its reactions may give valuable information [4].

Carbon isotope fractionations in natural gases

Abstract: THE origin of gaseous hydrocarbons has been considerably illuminated by isotope analyses of natural gases We shall try here to establish a model, explaining the isotopic fractionations of methane as a function of the thermocatalytic development of the corresponding source material Because the origin of gaseous hydrocarbons is closely related to the formation of crude oil on one hand and the thermocatalytic state of the organic source material on the other, isotopic investigations can be of great interest in exploration for hydrocarbons

Interrelations between sulfate-reducing and methane-producing bacteria in bottom deposits of a fresh-water lake. II. Inhibition experiments.

Abstract: A possible substrate interrelationship between methane-producing and sulfate-reducing bacteria has been studied in bottom deposits of Lake Vechten. Inhibition of methanogenesis in mud samples by chlorine-containing analogues of methane resulted in accumulation of acetate. Fluoroacetate reduced the concentration of methane by about 75%. With carbon tetrachloride, accumulation of hydrogen gas was observed. These results indicate that acetate is the main precursor of methanogenesis in mud. After addition of β-fluorolactate, lactate accumulated and H2S was no longer produced, which indicates that lactate is the main source of energy for sulfate reduction in mud. At the same time the concentration of methane increased possibly due to the lower concentration of H2S, which has a toxic effect on methanogenesis. Experiments with intact mud cores provide evidence that the described phenomena occur also in situ.

Nitrogen Fixation and Co-oxidation of Ethylene by a Methane-utilizing Bacterium

Abstract: SUMMARY: A methane-oxidizing bacterium, isolated from soil, was capable of fixing nitrogen. Nitrogenase activity could be assayed by acetylene reduction when the bacterium was growing on methanol but not when growing on methane, although 15N2 was fixed. Bacteria growing on methane co-oxidized ethylene but methanol-growing cells did not. The organism was extremely sensitive to oxygen when dependent on N2 as nitrogen source, a consequence of the sensitivity of its nitro-genase towards oxygen.

Method for removal of methane from coalbeds

Abstract: A method for removing methane gas from underground coalbeds prior to mining the coal which comprises drilling at least one borehole from the surface into the coalbed. The borehole is started at a slant rather than directly vertically, and as it descends, a gradual curve is followed until a horizontal position is reached where the desired portion of the coalbed is intersected. Approaching the coalbed in this manner and fracturing the coalbed in the major natural fraction direction cause release of large amounts of the trapped methane gas.

C 1 -C 4 hydrocarbons in the North and South Pacific

Abstract: Low molecular weight hydrocarbons in the surface waters of the North and South Pacific have been measured. Methane concentrations average 4.2 × 10 ?5 ml/1, while the C 2 -C 4 hydrocarbons averaged 1–5 × 10 ?6 ml/l. A large broad peak was found between 10° N and 10° S for the unsaturated hydrocarbons. Large concentrations of the C 1 -C 4 hydrocarbons were found in the different types of Antarctic sea ice. Atmospheric methane concentrations averaged 1.44 ± 0.04 ppm and decreased to 1.36 ± 0.04 ppm at the Intertropical Convergence Zone (ITC). DOI: 10.1111/j.2153-3490.1974.tb01953.x

High quality methane gas through modified anaerobic digestion

Abstract: Conventional anaerobic digestion, as practiced in municipal waste treatment plants, is modified to yield high-quality methane gas. Upwards of 98 percent methane is produced rather than the normal 60 to 70 percent methane (diluted with carbon dioxide). The process, wherein digestion is conducted under several atmospheres of pressure, involves the application of Henry's Law. Digesting sludge is used as a scrubbing agent. According to one system a recirculation loop features pressure release and degassing of carbon dioxide. Degassed sludge is then pumped, under pressure, back into a digestion tank. The recirculation rate is designed to maintain sludge in the digester in an unsaturated state with regard to carbon dioxide solubility. This keeps the carbon dioxide from precipitating out of the sludge within the digestion tank and results in high purity methane production. Another system accomplishes similar results by periodically depressurizing the digestion tanks to allow carbon dioxide to escape. This configuration requires no recirculation for degassification.

Steam Reforming of Hydrocarbons on Noble Metal Catalysts (Part 1)

Abstract: The catalytic activity of Group VIII transition metals except Os for methanesteam reaction under atmospheric pressure at 350∼600°C was investigated. The following activity sequence was obtained: Ru∼Rh>Ni>Ir>Pd∼Pt>>Co∼Fe.Ru and Rh were found to possess high and stable activity over a wide range of steam/methane ratio. The rate of reaction on a Rh-silica catalyst was found to be of the zeroth and 0.5th order with respect to methane and steam, respectively.

Occurrence of Natural Gas Hydrates in Sedimentary Basins

Abstract: Clathrates are a special variety of inclusion compound in which the guest molecules fit into separate spherical or nearly spherical chambers within the host molecule, and when the host molecule is water and the guest molecules are largely gases or liquids with low boiling points found in natural gas, the clathrates are termed natural gas hydrates. They are solid compounds, resembling ice or wet snow in appearance, and form both below and above the freezing point of water under specific PT conditions. The water molecules form pentagonal dodecahedra, which can be arranged into two different structures, leaving interstitial space in the form of either tetrakaidecahedra or hexakaidecahedra. Methane and hydrogen sulfide can be accommodated in all the spaces, ethane and carbon dioxide can fit in both the tetrakaidecahedra and the hexakaidecahedra, but propane and isobutane fit only in the hexakaidecahedra. Normal butane, pentane, and hexane are not known to form hydrates. PT diagrams describing the initial conditions for hydrate formation indicate that, relative to methane, all common components of natural gas (except nitrogen and the rare gases) raise the hydrate formation temperature, propane and ethane being the most effective. The presence of dis-solved salts in the water, or nitrogen and rare gases in the natural gas, depresses the temperature of initial hydrate formation.

Production, modification, and consumption of atmospheric trace gases by microorganisms

Abstract: Some trace gases are contained in the atmosphere in appreciable amounts: methane, carbon monoxide, hydrogen, nitrous oxide. The bulk of these gases is of biological origin. Hydrogen is a primary product of microbial metabolism under anaerobic conditions. However, before reaching the atmosphere, it is converted by methane bacteria to methane, by nitrate reducing bacteria to nitrogen and to nitrous oxide and by sulfate reducing bacteria to hydrogen sulfide. Carbon monoxide is produced from certain organic compounds. Hydrogen, methane, and carbon monoxide are quickly oxidized by microorganisms under aerobic conditions. However, especially methane and carbon monoxide reach the atmosphere. The literature dealing with the microorganisms and biochemical reactions involved in the production and conversion of trace gases is reviewed. DOI: 10.1111/j.2153-3490.1974.tb01947.x

Production of gases

Abstract: The invention is generally concerned with a process for the production of gaseous products by a chemical reaction, at least one reactant being liquid at normal temperature and pressure, which process comprises conducting the said reaction at a given pressure or a given temperature in the presence of a proportion of at least one of the reactants in the liquid phase, thereby controlling the temperature or the pressure of the reaction. The process is particularly useful for the catalytic gasification of light hydrocarbons with steam with water being present in the liquid phase, to produce a product gas which consists substantially of methane and carbon dioxide.

Prediction of soot formation rates: a new approach

Abstract: Five processes controlling the production of soot from gaseous hydrocarbons are distinguished: gas reactions producing radical fragments on which nucleation may begin; nucleation; coagulation; growth; and oxidation. A fundamental model capable of taking into account all these processes is described. The model is applied to the conditions of a practical rocket engine, in which production of soot in the exhaust jet is governed by the rate of pyrolysis of methane in the chamber. Predictions made for these conditions agree with experimental results. The rate controlling processes and key intermediate species are identified.