Carbon methanation

In the heating and cracking phase, preheated hydrocarbons leaving the atomizer are intimately contacted with the steam-preheated oxygen mixture. The atomized hydrocarbon is heated and vaporized by back radiation from the flame front and the reactor walls. Some cracking to carbon, methane, and hydrocarbon radicals occurs during this brief phase. 

When ethylene is polymerized, the reactor temperature should be well controlled to avoid the endothermic decomposition of ethylene to carbon, methane, and hydrogen ... 

Fig. 22.5. Concentrations of components (sulfate, sulfide, carbonate, methane, and acetate) and species (O2 and H2) that make up redox couples, plotted against temperature, during a model of the mixing of fluid from a hot subsea hydrothermal vent with cold seawater. Model assumes redox couples remain in chemical disequilibrium, except between 02(aq) and H2(aq). As the mixture cools past about 38 °C, the last of the dihydrogen from the vent fluid is consumed by reaction with dioxygen in the seawater. At this point the anoxic mixture becomes oxic as dioxygen begins to accumulate.

Atmospheric concentrations of (a) carbon methane, and (c) nitrous oxide over the past... 

Reactions may exhibit kinetic isotope effects as a result of the lighter isotope reacting faster. To illustrate this type of isotope effect, consider the oxidation of methane in the atmosphere (22). The oxidation is initiated by a reaction with the hydroxyl free radical (OH) in which OH irreversibly abstracts a hydrogen atom from the carbon. Methane molecules containing the lighter carbon isotope react faster, and as a consequence, the 613C value of the product is lower. 

Methane Methane is readily degraded aerobically by methanotrophs, which are members of the domain Bacteria that form CO2 and H2O from the methane, using it as a source of energy and carbon. Methane may also be anaerobically degraded in some marine environments by a microbial consortium consisting of an archaeon (e.g. a member of the Methanosarcinales) and a eubacterium (e.g. a member of the Desulfosarcinales) (e.g. Orphan et al., 2001). The archaeon forms H2 and CO2 from the methane, and the eubacterium uses the H2 to reduce seawater sulphate to H2S. The overall reaction brought about by this consortium is ... 

Hydrocarbon—Compound made from atoms of hydrogen and carbon. Methane (CH4) and propane (CjHg) are simple, gaseous hydrocarbons. Oil can vary from tar to very light liquid hydrocarbon to natural gas. 

For the purpose of utilization in the formation of hydro-oxygenated compounds of carbon, methane is partly burned so as to obtain a gaseous... 

The reaction with the lowest yield of standard free energy is methane fermentation with the products carbonate, methane, ammonia and phosphate. For details of these reactions, see Chapter 4. 

Aldehydes and ketones contain a carbonyl group (C=0) in which the carbonyl carbon is not directly attached to any atoms other than hydrogen or carbon. Aldehydes have either one or two hydrogens directly attached to the carbonyl carbon. Ketones contain only carbons directly attached to the carbonyl carbon. Methanal (common name formaldehyde) is the only aldehyde with two hydrogens attached to the carbonyl carbon. The simplest aldehyde with one hydrogen attached to the carbonyl carbon is ethanal (common name acetaldehyde). The simplest ketone is propanone (common names dimethyl ketone, acetone). 

Claypool G. E., Lorenson T. D. and Johnson C. A. (2(X)3) Authigenic Carbonates, Methane Generation and Oxidation in Continental Rise and shelf sediments, ODP Leg 188 Sites 1165 and 1166, Offshore Antarctica (Prydz Bay). In Proceedings of ODP, Scientific Results (eds. P. E. O Brien, A. K. COOPER, C. Richter and Shipboard Scientific Party), Vol. 188, pp. 1 -15. Available online from World Wide Web E-mail http //www-odp.tamu.edu/ publications/188 SR/VOLUME/CHAPTERS/004.PDF [cited 2003-02-10]. 

If the reaction temperature becomes too high, alternative decomposition reactions of ethylene to give a mixture of carbon, methane, and hydrogen may occur. These are also strongly exothermic, for example, the decomposition of ethylene to carbon and methane alone evolves 34 kcal/mol, and once initiated such reactions may cause pressure increases of explosive violence. Thus efficient control of reaction temperature is of paramount importance. 

Catalysts perform a crucial role during fuel processing. They should most catalyze the desired reactions (i.e., forming H2 and reducing CO) and least catalyze any undesired reactions (e.g., formation of carbon, methane and any other hydrocarbon compounds, and consumption of H2). Cheekatamarla... 

The characteristics of the storage system of active carbon-methane... 

Today carbon monoxide is readily accessible. It can be made easily by the gasification of either carbon, methane, higher boiling paraffins or crude oil. Gasification can be achieved by reacting the named materials either... 

Under ammonia synthesis conditions. Ruthenium is an active catalyst for the activated carbons methanation, which leads to the losing of supports and the... 

One of the important reasons of activated carbon supported ruthenium catalyst, which has not been widely applied, is the loss of activated carbon as support due to methanation. Therefore, it has theoretical and practical significance to study the reaction mechanism of activated carbon methanation and inhibition of methanation for ruthenium catalysts. 

Based on the above analysis, the main method of inhibition of activated carbon methanation is to reduce the edge carbon atoms which have unsaturated bond. The measures are listed as the following ... 

Zhu YF, The study of reaction and inhibition mechanism of activated carbon methanation on ruthenium catalysts. Dissertation, Hangzhou Zhejiang University of Technology. 2005. 

TABLE 8 Rama Ionization Oatector Rasponsa Factors Baaed on Pareantaga by Mass of Carbon, Methane Used as Unity... 

One of the well-known phenomena in high-pressure polyethylene processes is a rapid ethylene decomposition reaction or thermal runaway, known as decomp. At 300°C, ethylene and even polyethylene decompose to carbon, methane, hydrogen, and other hydrocarbon by-products. When the decomposition reaction takes place, the reactor pressure builds up quickly and the reactor must be vented, shut down, and flushed for a long period of time before a new startup is initiated. The resulting economic loss will be quite... 

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