Showing papers on "Methane published in 1969"

Tri-substituted methanes as organic photoconductors

Abstract: Alkylbis(N,N-dialkylaminoaryl)methane, cycloalkylbis(N,Ndialkylaminoaryl)methane and cycloalkenylbis(N,N-dialkylaminoaryl)methane are useful as photoconductors in electrophotographic elements.

Acid gas removal from gas mixtures

Abstract: An improved solvent and process for treating and separating acid gas, particularly hydrogen sulfide from gas mixtures containing the same, such as natural gas mixtures containing hydrogen sulfide, carbon dioxide and methane. The process involves the use of a solvent comprising a mixture of dimethyl ethers of polyethylene glycols to absorb the hydrogen sulfide and part of the carbon dioxide under superatmospheric pressure. The solvent containing dissolved hydrogen sulfide and carbon dioxide is flashed at reduced pressure to remove most of the carbon dioxide and produce a ''''semilean'''' solvent. Part of the semilean solvent is recycled to an intermediate part of the absorber; the remaining semilean solvent containing hydrogen sulfide is subjected to an oxygen containing gas under conditions that result in complete removal of the hydrogen sulfide to produce a ''''lean'''' solvent. The lean solvent is recycled to the top of the absorber. By the use of two solvent feeds to the absorber, the economy of the process is improved.

High Performance, Platinum Activated Tungsten Oxide Fuel Cell Electrodes

Abstract: HYDROCARBON fuels (methane, propane and so on) are relatively inert and can only be electrochemically oxidized using either high loading noble metal-black electrodes in phosphoric acid at 150° C or high temperature molten carbonate (or solid oxide) electrolyte cells at 600–1,000° C (ref. 1). Alternatively the fuel may be “reformed”, producing impure hydrogen (containing carbon dioxide and some carbon monoxide) which may be fed into a low temperature (> 100° C) acid fuel cell. Carbon monoxide, however, poisons platinum black by strongly adsorbing on its surface (with high coverage) at normal fuel cell anode potentials. Little opportunity exists for water molecules to adsorb on sites adjacent to surface CO molecules—a necessary condition for the removal of the latter by anodic oxidation2

The Photochemistry of Methane in the Jovian Atmosphere

Abstract: The photochemistry of methane in the Jovian atmosphere is reviewed and the photolysis of acetylene, ethylene and ethane is discussed. Approximate photochemical calculations are made for a mixed atmosphere of CH4 and H2 with a CH4 mixing ratio of 10−3. In regions where diffusion effects axe important, the solutions are modified to include these effects. Ethane is found to he the most abundant hydrocarbon produced in the photolysis of methane and has a mixing ratio on the order of 10−8 to 10−7. The densities of CH3, C2H2 and C2H2 are also given as a function of the H2 density. In the model CH4 is irreversibly converted into more complex hydrocarbons. It is suggested that the CH4 abundance is maintained on Jupiter by the downward transport of the more complex hydrocarbons into the hotter regions of the atmosphere where they undergo thermal decomposition to produce methane, which in turn is transported upward to replenish the methane lost in phoatolysis.

Distribution of methane and carbon monoxide between the atmosphere and natural waters

Abstract: Methane and carbon monoxide concentrations in the atmosphere and in natural waters were measured during an oceanographic cruise between Washington, D.C. and Puerto Rico. The concentration of methane was highest in the upper Potomac River and decreased as the ocean was approached. Methane was at equilibrium between the atmosphere and the open ocean, where its average concentration in the atmosphere was 1.24 +/- 0.03 ppm. Conversely, carbon monoxide concentrations increased in the open ocean relative to the river and bay waters. Equilibrium was not observed for carbon monoxide, and the net transport of this gas appears to be from the water into the atmosphere for all samples analyzed. Atmospheric carbon monoxide concentrations ranged from 0.075 to 0.44 ppm.

The reaction kinetics of gaseous hydrogen atoms with graphite.

Abstract: : The kinetics of reaction between solid graphite and gaseous atomic hydrogen was studied in the temperature range 450-1200K. The products of reaction are molecular hydrogen and methane. The rate exhibits an activation energy of 5.55 kcal/mole and is a function of the concentration of both hydrogen atoms and hydrogen molecules. Near 800K the rate goes through a maximum value, probably because of the thermodynamic instability of methane. A mechanism for the reaction is proposed. (Author)

Catalytic oxidation of methane over noble metals

Abstract: The complete oxidation of methane over palladium, platinum, rhodium and iridium has been studied using a microcalorimetric technique. The results indicated that methane may be adsorbed on two types of reaction site, one of which also adsorbs oxygen. The activation energies are proportional to the Pauling bond energies of the oxygen-metal bond in the region where the order in oxygen is low.

Total secondary ionization coefficients and breakdown potentials of hydrogen, methane, ethylene, carbon monoxide, nitrogen, oxygen and carbon dioxide between mild steel coaxial cylinders

Abstract: Breakdown potentials of hydrogen, methane, ethylene, carbon monoxide, nitrogen and carbon dioxide were measured at room and at elevated temperatures, and oxygen at 296 °K, using mild steel cylindrical electrodes. The gas pressure was varied over a range of almost four orders of magnitude, and the temperature of both the gas and the metal electrodes from 294-468 °K. Two discharge tubes, having different electrode diameters but the same material composition, were employed. The breakdown potential values at constant gas density, and for positive and negative wire (inner electrode), were found to be independent of gas temperature over the whole of the pressure and temperature ranges covered. It has been found that, with the exception of nitrogen, the similarity theorem is obeyed in the gases studied. This theorem was found to hold for positive as well as negative wire breakdown over a very wide range of gas pressure. The total electron yield due to secondary ionization processes was evaluated over a wide range of E/po values. The value of the total secondary ionization coefficient varied over a range of seven orders of magnitude, depending on the nature of the gas and the ion energy. The total secondary ionization coefficient was found to be independent of target and gas temperature in the gases studied, over the range 294-468 °K.

Infrared spectra, rotational correlation functions, band moments, and intermolecular mean squared torques of methane dissolved in liquid noble gases

Abstract: Extensive measurements of the infrared (i.r.) absorption spectra of liquid methane and of methane dissolved in liquid argon, krypton, and xenon have been carried out. Band profiles for the v3 and v...

A shock-tube investigation of the ignition of lean methane and n-butane mixtures with oxygen

Abstract: An investigation has been made of the ignition of shock-heated mixtures of methane and oxygen highly diluted with argon. The shocked-gas temperatures and pressures covered the ranges 1800° to 2500°K and 200 to 300 Torr, respectively. The ignition delay were inversely proportional to the oxygen concentration and a plot of log10(t[O2]) against inverse temperature yielded an apparent activation energy of 32 kcal mole−1. The addition of trace amounts of n-butane greatly reduced the ignition-delay times. A theoretical model has been used to study the ignition mechanism which utilizes the numerical integration of the reaction-rate expresions. Reasonable agreement with experimental data can be achieved if the major initiation reaction is the first-order dissociation of methane. The only oxidation reaction of the methyl radical is its bimolecular reaction with oxygen and, to achieve reasonable agreement with experiment, this must be assigned a value of about 0.8×1010 cm3 mole−1 sec−1 at 1875°K.

An evaluation of rate data for the reactions of atomic Oxygen (O3P) with methane and ethane

Abstract: This review presents in tabular and graphical form rate data on the reactions of atomic oxygen (O3P) with methane and ethane. The reliability of these data is discussed and suggested values of the rate constants are given over specified temperature intervals. Specific values are given for 298 and 1000°K.

Low pressure ethylene recovery process

Abstract: Process for the removal of methane from a hydrocarbon feed containing ethylene, methane and higher boiling hydrocarbons with minimum loss of ethylene. Methane is separated overhead from the feed in a separation zone at a first lower pressure; a first portion of this overhead vapor is expanded through an expansion motor producing an energy output, a second portion of the overhead vapor is compressed to a second pressure greater than the first pressure in a compressor driven by the motor output. The compressed vapor portion is then cooled to condense the major portion of the methane and the condensed methane is returned to the separation zone as reflux and recovering ethylene as bottoms from the separation zone. The methane vapor is recovered as fuel gas.

The combustion of methane in a jet-mixed reactor

Abstract: The combustion of premixed methane-oxygen-nitrogen mixtures in the range T=1400–1800°K and P=0.3–1.1 atm was investigated in a small (2.9 cc) conical reactor fed by a single-choked sonic-flow jet (see Fig. 3). Reaction products were chromatographically analyzed and these data, in conjunction with metered inputs and measured combustion temperatures, were used to derive over-all burning-rate correlations for methane and carbon monoxide in the temperature range 1450–1750K°, at pressures from 0.3–0.8 atmospheres, with equivalence rations from 0.5–0.8. The over-all rate expressions found were dX/dt=kx exp(−Ex/RT)fxfO21/2fH2O1/2(P/RT)2 where X=CH4 kx=5.3×1015 liters/g mole see when P/RT=g moles/liter Ex=57±5 kcal. X=CO kx=1.8×1010 liters/g mole sec Ex=25±5 kcal. The data support the widely held belief that the rate-limiting step in methane oxidation in lean flames in this temperature range is the reaction of methane with hydroxyl radical followed after some less well understood fast steps by a second rate-limiting reaction of carbon monoxide with hydroxyl. The data also indicate that three-body collisions involving two free radicals are of limited importance in fast methane oxidation. An extensive computer simulation of the performance of a jet-mixed reactor wherein methane burns in two major steps (1, CH4→CO+2H2O followed by 2, CO→CO2) was carried out. The results of this simulation showed that, for a fast reaction with a high activation energy, significant inhomogeneities (i.e., departure from the approximation of perfect mixing) in reactant concentrations existed because of inadequate mixing within the reactor. (The computations also showed that the assumption of perfect mixing is reasonable if the reaction being studied is slow and of low activation energy.)

PVT Properties of Methane and Propene to 10 kbar and 200°C

Abstract: Isotherms of CH4 and C3H6 have been determined between about 1 and 10 kbar at temperatures of 35°, 100°, and 200°C. The results are reported.

Reactions of nitroalkanes in the gas phase. Part 1.—Pyrolysis of nitromethane

Abstract: The pyrolysis of nitromethane has been studied between 305 and 440°C. The reaction is pressure dependent. Above 150 mm, it is approximately first order, k= 1014.1 exp (–55,200/RT) sec–1. The principal products are methane, carbon monoxide, nitrogen, nitric oxide, hydrogen cyanide and water. The results are explained by considering the reactions of methyl: CH3·+ CH3NO2→ CH4+·CH2NO2, CH3·+ NO2→ CH3NO2, CH3·+ NO2→ CH3O·+ NO, CH3·+ NO → CH3NO The product distribution depends on the relative concentrations of nitric oxide and nitrogen dioxide in the system, and this is confirmed by studying the ratio of products formed on addition of excess formaldehyde and nitrogen dioxide.

Ion–Molecule Reactions in Alpha‐Particle‐Irradiated Methane and Water Vapor

Abstract: Ion–molecule reactions in methane and water vapor are investigated for the various primary, intermediate, and secondary species formed in parent gases bombarded by 1–3.5‐MeV alpha particles. Reaction rates for CH4+ and CH3+ colliding with methane gas and for H2O+ and OH+ colliding with water vapor are given and compared to similar data obtained by others using electron ionization. Single alphas are detected, counted, and their number compared to the number of ions formed in the reaction chamber. A pulsed time‐of‐flight type of mass spectrometer is used to vary ion–molecule reaction times and to separate ions according to their mass to charge ratios. The well‐defined “zero” time of interaction in this pulse counting experiment allows one to estimate a “lifetime” for shortlived intermediates; the results indicate a lifetime near 0.18 μsec for the excited (C2H7+)* ion formed as a collision complex of CH3+ and CH4. These experiments also reveal that collisions between either the OH+ or H2O+ ions with water va...

Trapping of the methyl cation by carbon monoxide; formation of acetic acid from methane

Abstract: The formation of acetic acid from methane, carbon monoxide, antimony pentafluoride, and water is reported, confirming the occurrence of the methyl cation (CH3+) in the oligocondensation of methane and indicating that protonated methane (CH5+) is not involved in this reaction.

Electric Discharge Reactions in Mixtures of Phosphine, Methane, Ammonia and Water

Abstract: Electric discharge reactions in mixtures of phosphine with methane, ammonia and water, obtaining biologically significant inorganic and organic phosphorus compounds

Pressure‐Induced Infrared Spectrum of Methane

Abstract: Abstract : The pressure-induced infrared absorption spectrum of gaseous methane was observed using a 10m cell and 4-10 atm. pressure in the region 200-550 cm. The intensity can be expressed according to the relation: A(nu) = gamma(nu)(d sq), where A(nu) is the absorbance at frequency nu, and d is the gas density. The spectrum is interpreted in terms of rotational transitions in a pair of CH4 molecules possessing a transient dipole moment induced by the octopole moment of the molecule. (Author)

Studies of methane absorption in the Jovian atmosphere. II

Abstract: Methane abundance in Jovian atmosphere deduced from line equivalent widths, obtaining line intensity for J manifolds

Destruction of methane in water gas by reaction of CH3 with OH radicals

Abstract: The decay of residual methane in the burned gas from fuel-rich methane oxygen flames can be expressed − d [CH 4 ]/ dt =9×10 14 ([CH 4 ][H 2 O]/[H 2 ]) exp (−117 kcal/ RT ) moles cm −3 sec −1 in the ranges [H 2 O]/[H 2 ]=0.6 to 1.1, and T =1970° to 2190° K. The equilibria CH 4 =CH 3 +0.5 H 2 H 2 O=OH+0.5 H 2 are both satisfied, and the probable interpretation of the experimental expression is that methane decays at the rate of reaction of CH 3 with OH radicals. If so, the rate constant for this radical-radical reaction is 4(±2)×10 12 cm 3 mole −1 sec −1 , and is insensitive to temperature in the range covered.

The photochemistry of Jupiter above 1000 Å.

Abstract: Jovian photochemistry above 1000 A appears to consist of four zones: 1) photolysis of methane at 1216 A and a total pressure of less than 10−5 atm; 2) photolysis of ammonia at 1700–2200 A and a total pressure of less than 5×10−4 atm; 3) photolysis of both methane and ammonia at 1350–1450 A at a total pressure of about 10−4 atm; and 4) photolysis of ammonia at 1450–1700 A at a total pressure 1000 A because of the reducing atmosphere. Methane and ammonia persist in the atmosphere because photochemical mechanisms for their destruction ultimately results in their reformation by reaction of such species as CH2, NH and NH2 with H2.