Steam, reaction with carbon

Fig. 9. Ideally, the predicted variation in the relative rates of the carbon-oxygen and carbon-steam reactions with temperature for a porous carbon.

Carbon dioxide and steam are the activating agents most commonly used, whose reactions with carbon are endothermic. These gases react with the carbon atoms in the precursor according to the following reactions ... 

DIETHYLMAGNESIUM (557-18-6) Violent reaction with moisture, water, steam. Contact with carbon dioxide causes ignition. 

OXICLORURO de FOSFORO (10025-87-3) Fumes in moist air. Contact with water, steam, or alcohols produces hydrochloric acid, phosphoric acid, and phosphine gas, which is pyrophoric, with possible ignition or explosion (may be a delayed reaction). Contact with air produces corrosive fumes. Violent reaction with carbon disulfide, 2,6-dimethylpyiidine-M-oxide, dimethyl sulfoxide, ferrocene-l,l -dicarboxylie acid, pyridine, zinc powder. Reacts, possibly -violently, with acids, alkali metals, alkalis, combustible materials, dimethyl formamide, organic matter, zinc powder. Incompatible with acetic anhydride, iV,A -dimethyl formamide, 2,5-dimethylpyrrole, sodium. Rapid corrosion of steel and most metals, except lead, occurs in the presence of moisture. 

It is also possible to reform methane by reaction with carbon dioxide, rather than with steam, so-called dry reforming ... 

Active carbons have been commercially produced by steam reaction with carbonaceous materials. The activating gas in the process is thought to penetrate the particle as a result of diffusion accompanied by chemical reactions. The endothermic character of the reactions may lead to a temperature decrease in the reaction zone while heat flows slowly to the deepest layers of the particle. Due to these factors, the burn-off of the carbonaceous substance is a function of the position within the particle. 

Mechanisms of reactions with molecular oxygen are well understood because they have received considerable research investment. There exist similarities of reactions with molecular oxygen and reactions with carbon dioxide and steam (water vapor). Initially, it is irrelevant to discuss in some detail the carbon-molecular oxygen reaction, but, as is clarified later, this discussion also provides meaningful clues as to how carbon atoms are extracted in a gasification process by carbon dioxide or steam. 

The endothermic character of the gasification reactions with carbon dioxide and steam facilitates the accurate control of experimental conditions in the furnace, but it also makes necessary the use of direct heating in order to maintain reaction temperatures. The heat supply is generated by introducing controlled amounts of air into the furnace to bum natural gas (when added) and the gases produced during activation (CO and H2) ... 

Molten carbonate cells have been operated on a variety of fuels carbon monoxide, hydrogen, kerosene and a variety of hydrocarbon gases mixed with steam. The reaction with carbon monoxide is... 

When the steam to carbon ratio in the reforming section is not reduced below the critical limit for carbide formation, it is possible, by adding an extra shift catalyst bed after the conventional shift unit, to reduce the carbon monoxide leakage to around 0.05 dry vol%. This means that less hydrogen will be lost by reaction with carbon monoxide in the methanator, and that tht synthesis loop will become more efficient due to the lower inert content in the make-up gas. 

Chemical Use. Both natural gas and natural gas Hquids are used as feedstocks in the chemical industry. The largest chemical use of methane is through its reactions with steam to produce mixtures of carbon monoxide and hydrogen (qv). This overall endothermic reaction is represented as... 

The soaking phase takes place in the rest of the reactor where the gas is at high temperatures. A portion of the carbon disappears by reactions with CO2 and steam. Some carbon, about 1—3 wt % of the oil feed, is present in the product gas. Natural gas feedstock produces only about 0.02 wt % of carbon. 

After the steam reforming step, the product gas stream contains a considerable quantity of carbon monoxide which may undergo reaction with additional steam, thereby increasing the hydrogen yield ... 

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