Methane from decomposition

Kim et al. [123] conducted the kinetic study of methane catalytic decomposition over ACs. Several domestic (South Korea) ACs made out of coconut shell and coal were tested as catalysts for methane decomposition at the range of temperatures 750-900°C using a fixed-bed reactor. The authors reported that no significant difference in kinetic behavior of different AC samples was observed despite the differences in their surface area and method of activation. The reaction order was 0.5 for all the AC samples tested and their activation energies were also very close (about 200 kj/mol) regardless of the origin. The ashes derived from AC and coal did not show appreciable catalytic effect on methane decomposition. 

Li, Y. et al., Simultaneous production of hydrogen and nanocarbon from decomposition of methane on nickel-based catalyst, Energy Fuel, 14,1188, 2000. 

The combination of C02 injection and methane production over specific PT regimes allows the heat effects of C02 hydrate formation and methane hydrate decomposition to nullify each other resulting in a sustainable delivery process which both reduces C02 emissions to combat global warming and recovers methane to supplement the declining reserves of conventional natural gas (Fig. 4). This gas hydrate phase-behaviour in response to the dissociation and formation processes clearly demonstrates the potential of C02 enhanced CH4 recovery from the Mallik gas hydrate deposit. 

Methanogen An organism capable of producing methane from the decomposition of organic material... 

Recently, several new processes for methane thermal decomposition were reported in the literature. In one report, the authors proposed a methane decomposition reactor consisting of a molten metal bath.8 Methane bubbles through molten tin or copper bath at high temperatures (900°C and higher). The advantages of this system are efficient heat transfer to a methane gas stream and ease of carbon separation from the liquid metal surface by density difference. In... 

Rates of the losses of methyl and methane from the molecular ion of methylcyclopentane have been determined over the time range 40 ps to microseconds [288]. The loss of ethylene from methylcyclopentane and decompositions of methylcyclohexane were also investigated. With support from I3C labelling, it was suggested that at times shorter than 1 ns, methyl was lost from the intact cyclopentane ion, but that at longer times ring opening preceded the decomposition. 

The bis(chlorosilyl)methanes were the same products as those obtained from the direct reaction of silicon with a mixture of methylene chloride and hydrogen chloride, indicating that some of the starting chloroform decomposed to methylene chloride during the reaction. When the isolated tris(chlorosilyl)methanes were fed into the reactor under the reaction conditions, they did not decompose to bis(chlorosilyl)methanes. The decomposition of chloroform was suppressed and the production of polymeric carbosilanes reduced by adding hydrogen chloride to chloroform. As a result, the deactivation problem of elemental silicon was eliminated. Cadmium was a good promoter for the reaction, while zinc was found to be an inhibitor. 

Reaction (2) corresponds to the successive reactions (3) to (8). Because H is dissociatively adsorbed on Ni, numerous highly reactive hydrogen atoms are available on the surface and consequently, hydrogenation reactions (3), (5) and (7) are catalysed on nickel. Reactions (9b and 10) describe the decomposition of the ligand C Hj. Incorporation of aliphatic carbon is represented by reaction (lOa) that of interstitial or graphitic carbon is represented by reaction (10b). Incorporation of condensed species is represented by reactions (9c) and (9d). The methanation of carbon on nickel, reaction (12), has been extensively studied and references therein), generally from decomposition of CO, because it plays a key... 

In contrast, only methane, propylene, butadiene (all three in approximately equal quantities), and hydrogen comprise the major products obtained from decomposition of either cis- or trans-2-butenes under a variety of conditions (5). While isomerization occurred in all cases, equilibrium isomer distribution was never achieved. Ethylene was observed among the products at high temperatures and high conversion levels. Skeletal isomerization has not been observed however, at low temperatures (6,7) substantial conversion to 1-butene has been reported. 

The effect of electrical fields on the radiolysis of ethane has been examined by Ausloos et and this study has shown that excited molecules contribute a great deal to the products. The experiments were conducted in the presence of nitric oxide, and free-radical reactions were therefore suppressed. The importance of reactions (12)-(14) was clearly demonstrated by the use of various isotopic mixtures. Propane is formed exclusively by the insertion of CH2 into C2H6 and the yield is nearly equal to the yield of molecular methane from reaction (14). Acetylene is formed from a neutral excited ethane, probably via a hot ethylidene radical. Butene and a fraction of the propene arise from ion precursors while n-butane appears to be formed both by ionic reactions and by the combination of ethyl radicals. The decomposition of excited ethane to give methyl radicals, reaction (15), has been shown by Yang and Gant °° to be relatively unimportant. The importance of molecular hydrogen elimination has been shown in several studies ° °. ... 

With the exception of formic acid, the lower fatty acids are quite stable np to relatively high temperatures. Cahours and Berthelot early notedos the thermal stability of these acids, and the latter reported that acetic acid did not decompose until above a dull red heat. More recently Senderens showed that acetic, propionic, /i-butyric, isobutyric, and isovaleric acids were perfectly stable at temperatures as high as 460° C.os At higher temperatures these acids undergo pyrogenic decomposition to yield simple and stable substances. In the case of acetic acid, Nef 01 reported the presence of methane, carbon dioxide, carbon monoxide, ethylene, hydrogen, and acetone in the products from decomposition. 

Because of the possible importance of the process for the production of a liquid motor fuel from coal and the possible bearing it might have on the synthesis of oxygenated products from water-gas, a considerable amount of research has been expended on the problem both in this country and abroad.111 The reverse reactions, however, are of limited importance since at the temperatures required, the aliphatic hydrocarbons higher than methane undergo decomposition reactions in the presence of the active catalysts. 

Kinetics of decomposition at short times (methyl radical from the n-butane [825], 2, 2-dimethylbutane [240] and 2, 2-dimethylpentane [240] ions, loss of ethyl from n-heptane, n-hexane and n-octane ions [522, 825], loss of methane from the neopentane ion [825], and loss of ethane from the 3-ethylpentane ion... 

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