Methane limiting oxygen concentrations

Based on these results, the authors concluded that the optimum conditions for the production of higher alcohols from methane series hydrocarbons are as follows pressure, from 130 to 200 atm the lowest possible temperature the residence time in the heated reactor, less than 10 s and as high as possible (within safe operation limits) oxygen concentration. It was concluded that, in the oxidation of alkanes, low pressure favours the formation of lower alcohols and organic acids, whereas high pressure promotes the formation of higher alcohols and aldehydes [26]. 

The presence of alkali on the surface of mixed oxides, added as a promoter or fixed into the solid structure as in layered perovskites, significantly improved the C2 yield, suggesting that these elements influence the oxygen species responsible for the formation of methyl radicals and/or limit the concentration of those oxygen sites associated with the total oxidation of methane. 

Grade C, Type II is typical of Hquid oxygen used as a rocket propellant oxidizer. Particulate content is limited because of the critical clearances found in mechanical parts of the rocket engine. In addition to water, acetylene and methane are limited because, on long standing, oxygen evaporation could cause concentration of these combustible contaminants to reach hazardous levels. 

Ethylene oxide is produced by adding ethylene, oxygen, a methane diluent, and recycled carbon dioxide to a continuous reactor. Gaseous compositions are controlled carefully to keep the concentrations outside the explosion limits. 

Chloroform in aqueous solutions at concentrations ranging from 1 to 10% of the solubility limit were subjected to y rays. At a given radiation dose, as the concentration of the solution decreased, the rate of decomposition increased. As the radiation dose and solute concentration were increased, the concentrations of the following degradation products also increased methane, ethane, carbon dioxide, hydrogen, and chloride ions. Conversely, the concentration of oxygen decreased with increased radiation dose and solute concentration (Wu et al, 2002). 

The ACGIH has not assigned a numerical threshold limit value (TLV) for occupational exposure to methane because the limiting factor is the available oxygen, the minimal content of which should be 18% by volume under normal atmospheric pressure at concentrations below those required to produce any severe oxygen deprivation, methane presents an explosive and flammable hazard. ... 

The enhancement in CO hydrogenation activity of Rh is ascribed to the presence of Ti + sites at the perimeter of TiOx islands. It is proposed that these sites interact with the oxygen in CO chemisorbed on nearby Rh atoms and assist in the disociation of CO. Since the disociation of CO is believed to be the rate-limiting step in this reaction, the participation of Ti + in this step leads to a higher activity. The dependence of the methanation rate on TiOx coverage, seen in Fig. 5, is attributable to the variation in the concentration of Ti + centers with TiOx coverage. 

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