Oxidation of methane

Oxidation of Methane. The direct selective transformation of methane to methanol and formaldehyde, two valuable industrial chemicals is a goal that is extremely 

It includes the steam reforming of methane over a nickel catalyst to synthesis gas followed by the copper-catalyzed transformation of the latter to methanol (see Section 3.5.1). Finally, formaldehyde is produced by oxidative dehydrogenation of methanol. 

One disadvantage of this technology is the large energy requirement of the first, highly endothermic, step. The process is also inefficient in the sense that it first transforms methane in an oxidative reaction to carbon monoxide, which, in turn, is reduced to methanol, and the latter is oxidized again to formaldehyde. The direct conversion of methane, therefore, would be a more efficient way in the production of methanol and formaldehyde. 

The main problems associated with the direct oxidation of methane are the higher reactivity of the products (methanol and formaldehyde) compared to methane, and the thermodynamically more favorable complete combustion of methane to carbon oxides and water  

Therefore, finely tuned reaction conditions to achieve high conversion without total oxidation are required. At present, however, there is no commercially viable process satisfying these requirements. 

Partial oxidation reactions have been examined to oxygenate hydrocarbons such as methane in the absence of catalyst in SCH2O, whereas in SCCO2, Xe, and Kr, partial oxidations using heterogeneous metal catalysts have been studied by Knopf et al. [77], Suppes et al. [78] and McHugh et al. [79]. Non-cata- 

Penninger [97] also demonstrated that water functions as a significant reactant affecting the decomposition pattern of di-n-butylphthalate in the temperature range from 305 °C up to 390 °C and water densities up to 0.31 g/nd. It favors hydrolytic decomposition, which results in o-phthalic acid, butanol and butene, whereas in the absence of water the thermolysis results in only 

None of the products formed in the reactions described above is considered to significantly change the reaction rates and product distributions by acting as a catalyst. However, Siskin et al. [106] reported that in the hydrolysis of methyl 1-naphthoate at 343 °C naphthalene was predominantly formed because the potential for autocatalysis arises. They concluded that decarboxylation of naphthoic acid, the main product at a lower temperature of 250 °C, led to the formation of naphthalene at 343 °C the reaction is catalyzed by the generated carbonic acid. In the hydrolysis of typical p-keto esters, ethylacetoacetate was completely converted to acetone, eAanol, and CO2 within 30 min at 250 °C. Under the same conditions, r-butyl acetate degraded into a bright red, insoluble mixture of unidentifled products resulting from polymerization of isobutylene [107]. 

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Very extensive investigations have been conducted on the oxidation of methane over a number of heterogeneous catalysts, particularly —MgO... 

With the addition of CO caused by photochemical oxidation of methane, a significant flux enters the atmosphere annually, but the principal global contributions are terrestrial, anthropogenic and from atmospheric photolysis of methane. 

The main reaction occurring in the secondary reformer is the partial oxidation of methane with a limited amount of air. The product is a mixture of hydrogen, carhon dioxide, carhon monoxide, plus nitrogen, which does not react under these conditions. The reaction is represented as follows ... 

The oxidation of nitric oxide, NO, is a reaction involved in smog production. It is moderately rapid at normal temperatures. The oxidation of methane, CHt (household gas), however, occurs so slowly at room temperature that we may say that, for all practical purposes it doesn t react at all. Again, the difference in the reaction rates must depend upon specific characteristics of the reactants, NO and CH,. 

By far the majority of the million or so known compounds of carbon also contain hydrogen and oxygen. There are several important types of oxygen-containing organic compounds and they can be studied as an oxidation series. For instance, the compound methanol, CH3OH, is very closely related to methane, as their structural formulas show. Methanol can be regarded as the first step in the complete oxidation of methane to carbon dioxide and water. 

Methanol can be produced relatively cheaply as a bulk chemical by the oxidation of methane. Several processes have been developed to produce feed-grade SCP using methanol as a substrate. We will now examine one such process in depth, to show how a process is developed, from inception to production scale, and how the many problems encountered can be tackled and overcome. 

The lower than expected yields can be explained by the nature of methane oxidation to methanol in these bacteria. This reaction, catalysed by methane mono-oxygenase, is a net consumer of reducing equivalents (NADH), which would otherwise be directed to ATP generation and biosynthesis. In simple terms the oxidation of methane to methanol consumes energy, lowering the yield. 

The second principle was the great defensive strength of an established, capital intensive procedure. In the overall process for making acrylonitrile via acetylene, very big plants were needed for making the acetylene either by partial oxidation of methane or from carbide furnaces. Manufacture of HCN from methane involved further expense ... 

Oxidation of methane is one of the sources of atmospheric CO. Another internal source of importance is the oxidation of terpenes and... 

For direct oxidation of methane, it is shown [12] that the mechanism is ... 

Direct oxidation of methane to methanol is an obvious dream reaction ... 

The catalytic partial oxidation of methane into CO and H2 according to... 

Schouten S, SG Wakeham, EC Hopmans, JSS Damste (2003) Biogeochemical evidence that thermophilic archaea mediate the anaerobic oxidation of methane. Appl Environ Microbiol 69 1680-1686. 

For the partial oxidation of methane a catalytic membrane system under development by researchers at the Argonne National laboratory [8] effectively... 

Li/MgO(100) Mo(lOO) thin film (selective oxidation of methane to ethane) (7)... 

The Active Oxygen for Direct Oxidation of Methane to Methanol in the Presence of Hydrogen... 

Partial oxidation of methane to synthesis gas over Ru/Ti02 catalysts... 

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