Methane pressure

During the incubation period, methane pressure builds up in submicroscopic voids. These voids grow slowly due both to internal methane pressure and applied stress. When the... 

Circone, S. Stem, L.A. Kirby, S.H. (2004a). The effect of elevated methane pressure... 

A suspension of potassiumperoxodisulfate in a mixture of trifluoroacetic acid and trifluoroacetic acid anhydride at a methane pressure of 20-30 atmospheres methane and 80-100 °C in the presence of catalytic amounts of 18 and 20 leads to the formation of the trifluoroacetic acid methylester. Scheme 23 shows the oxidative character of the reaction which formally can be described as CH4 [CH3]" -1- H -l- 2e". 

For the catalytic functionalization of methane 0.21 mmol of compoimd 18 and 100 equivalents K2S2O8 are suspended in a mixture of 60 mL trifluoroacetic acid and 10 mL trifluoroacetic acid anhydride and are transferred into an autoclave. With an initial methane pressure of 20 atmospheres and a temperature of 80 °C the only product is trifluoroacetic acid methylester (510% yield relative to palladium). 

Both reactions exhibit a similar order with respect to methane pressure on each metal and the constant difference of —0.5 in the order with respect to deuterium pressure suggests that reaction B involves one less hydrogen atom than reaction A. The orders are consistent with the following mechanisms for the rate-detennining steps... 

The oxygen consumption in the partial combustion process is a function of the preheat temperatures of the gas and oxygen, the heat leak from the combustion zone, and the efficiency of the burner which is measured by the terminal temperature required for a given conversion of methane. Pressure and space velocity are also important variables but their effect can easily be obscured by small changes in burner performance or terminal temperature. 

Fig. 3. Cycling operation with pure methane pressure profiles (continuous line and left hand scale), adsorbed volume of methane per volume of composite block (symbol ( ) and right-hand scale).

In a typical reaction, a 5 mL glass-lined, stirred, high-pressure reactor containing 20-50 mM of catalyst [HgS04, Pt(bpym)Cl2 or 20-mesh Au powder] was added 3mL 96% H2S04 with methane (pressure 300-800 psig). If Au was used H2Se04... 

Also, relevant thermodynamic data (Table 4.2) indicate that the rise of the methane pressure during standard aromatization of C2 C4 alkanes must result in the direct insertion of methane into aromatic hydrocarbons at 720 770 K (450 500°C) that is, by reaction 2C3H8 -F CFI4 CgFIsCFIs + 6FI2 (see Table 4.2). 

Fig. 11. Rates of products formation as a function of methane pressure in the COS-...

The mole fraction of methane, CH4, dissolved in water can be calculated from the Henry s Law constants of 4.13 X 10 atm at 25°C and 5.77 X 10 atm at 50.°C. Calculate the solubility of methane at these temperatures for a methane pressure of 10. atm above the solution. Does the solubility increase or decrease with increasing temperature (See Exercise 17 for interpretation of units.)... 

Wolczanski also investigated the chemistry of a tantalum imido system. In this system, elimination of hydrocarbon from the bis-amido imido complex occurs with difficulty at 183°C to give an amido bis-imido complex. The elimination is reversible, with the bis-imido species not being directly observed (Scheme 10). Under methane pressure, the phenyl complex loses benzene and adds methane. Neopentane, benzene, and toluene (benzylic activation) were also found to undergo activation, but not cyclohexane. The authors conclude from their equilibrium studies that the differences in metal-carbon bond strengths are approximately equal to the differences in carbon-hydrogen bond... 

The volume of 1 kmol of methane at 300 K is 2.5 mT Compare the methane pressure calculated by (a) the ideal gas equation, (b) the virial equation, (c) the Redlich-Kwong equation, and (d) the Soave equation. The following data are available ... 

The decomposition of methane in the glow discharge has been investigated for many years. At low pressures ethane was the major product13. As the methane pressure... 

Compartment A contained two electrodes for applying an electric field during irradiation. Both the polarity on, and field strength between the electrodes were variable. EB-A was only 1 mm. from Electrode 1, so that when this electrode was negatively biased, at least 96% of the positive ions formed in EB-A at a methane pressure of 0.1 torr were collected (40). 

Figure 6. Abundance of the CHS and CtHs radicals produced by the radiolysis of methane with 100 e.v. electrons as a function of methane pressure...

Both systems are capable of methane activation. When a solution of ( -C5Me5)Ir(CO)2 is irradiated under methane pressure, insertion produces ( y -C5Me5)IrCO(H)(CH3) in ca. 20% yield . The low kinetic barrier to alkane activation is shown by the reaction of methane even at 12 K with the species generated by photolysis of ( -C5Me5)Ir(CO)2 to give the hydridomethyl species . 

Taking p(H20) = 3 x 10-2, p(C02) = 3x 10-4, p(H2) = 5 x 10-5, we find an equilibrium pressure for methane of 100 bar. The calculation ignores the fact that the supply of hydrogen is limited and the methane pressure cannot exceed the initial pressure of hydrogen, but the result demonstrates the... 

Example 7.5. The equilibrium liquid from the flash drum at 100°F and 485 psia in Example 7.2 is fed to a stabilizer to remove the remaining hydrogen and methane. Pressure at the feed plate of the stabilizer is 165 psia (1138 kPa). Calculate the percent vaporization of the feed if the pressure is decreased adiabatically from 485 to 165 psia by valve and pipe line pressure drop. 

The temperature dependence of methane combustion over Pd-SAPO-5 at various methane pressures is shown in Figure 24. Clearly, methane conversion increased with decreasing CH4 concentration, which agrees well with the chemical equilibrium. When 0.5 vol% methane was supplied, combustion of CH4 began at 573 K, and 90 percent conversion was attained at 723 K. Furthermore, the methane was completely oxidized above 823 K. 

The methane migration during coal mining is caused by loss of the in-situ equilibrium between the coal skeleton stress and methane pressure. The interactions between coal deformation and methane migration have several aspects effective stress change in coal seams due to excavation and mining, porosity change and methane content increase,... 

In order to investigate reaction kinetics, DSC experiments were performed at different heating rates ()3= 10, 20, and 50 K/nnin). The inert gas was argon at 1 bar pressure and a flow rate of 5 cmVmin. Additional experimental runs were performed in methane at 10 bar pressure and at a flow rate of 5 cmVmin in order to study the influence of a hydrocarbon atmosphere and to simulate the thermal cracking process. Unfortunately, methane pressure highter than 10 bar was not available, so the conditions of the cracking process could not be simulated perfectly. 

When D2O was substituted for H2O no deuterium was found in the unreacted methane analysed mass spectrometrically at 10% conversion of methane to carbon monoxide. No H-D exchange with hydrogens of methane has been observed in the CH4 -h H2O -h D2 system. In the case of nickel catalyst supported on y-alumina F containing 7.0% Ni) the kinetic dependences (log rate versus log Pch4 nd log Ph2o) e different. Some incorporation of deuterium into methane was found when the CH4 -h D2O reaction was carried out at 10 torr of CH4. The rate of the reaction Wfor low methane pressures (at constant hydrogen pressure) has been found to be... 

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