Cracking of methane

Aiello, R. et al., Hydrogen production via direct cracking of methane over Ni/Si02 Catalyst deactivation and regeneration, Appl. Catal. A General, 192, 227, 2000. 

Steinfeld, A. et al., Production of filamentous carbon and hydrogen by solar thermal catalytic cracking of methane, Chem. Eng. Sci., 52,3599, 1997. 

One of the possible problems in a steam reforming membrane reactor is the formation of carbon, either by cracking of methane (Reaction 4) or the Bou-douard reaction (Reaction 5). 

The reverse reaction, steam cracking of methane, involves the same elementary steps as the methanation reaction. The kinetics for that reaction have been developed for a single direct mechanism by Snagovskii and Ostrovskii (39). 

Clearly the rate equation for the cracking of methane, i.e. for the coke formation is not fundamentally different from that of one of the main reactions (12). What remains to be done is to link the coke content of the catalyst to the rate of the main reactions. Thereby a specific aspect of coke formation on Ni/alumina catalysts has to be accounted for, namely whisker formation. The rate equation (16) is not directly applicable because it contains the concentration of coke adsorbed on the Ni-surface, which is not accessible, just like Cc 4., C. i,... The latter are eliminated through adsorption-isotherms in favor of the measurable gas phase partial pressures PcH4. Ph2> but this is not possible for coke. What is done in the derivation of (5) and (6), where the same problem is already encountered, is to manipulate the expressions so as to factor out the Cq, thus yielding the... 

Ahmed S, Aitani A, Rahman F, Ali Al-Dawood, Al-Muhaish F (2009) Decomposition of hydrocarbons to hydrogen and carbon. Appl Catal A-Gen 359 1-24 Aiello R, Fiscus JE, Eoye HC, Amiridis MD (2000) Hydrogen production via the direct cracking of methane over Ni/SiO catalyst deactivation and regeneration. Appl Catal A-Gen 192 227-234... 

It seems more interesting to utilize the discovered mechanisms of methane conversion into higher hydrocarbons for catalytic cracking of methane into carbon and hydrogen. 

Hydrogen can also be produced by the direct thermolysis or thermocatalytic decomposition ( cracking ) of methane or other hydrocarbons. The energy requirement per mole of methane is in fact less than that for steam reforming (although only half as much hydrogen is produced) and the process is simpler. 

In accordance with these equations, ethane, ethylene, acetylene and elemental carbon are produced by the cracking of methane. Activation energy of this process is 76 kcal mol. The formation of acetylene starting from methane or ethane are endothermic processes ... 

The results of the samples regenerated by H2 and O2 after the POM and R reactions and the catalyst submitted to carbon deposition by cracking of methane are similar. 

Hydrogen Production by Catalytic Cracking of Methane Using Ni-A Os Catalysts. Influence of the Operating Conditions... 

The reaction of direct cracking of methane over nickel catalysts has recently been receiving attention as an alternative route to the production of hydrogen from natural gas [5-10], This reaction is moderately endothermic, and is displaced towards the carbon formation at temperatures above 560 C ... 

Cracking of methane or other hydrocarbons, combustion of hydrogen, and sequestration of carbon... 

If compression of hydrogen is replaced by Uquefaction (-1-50,000 kJ/kgjjj), approxi-rrrately 85% of the heat of combustion of methane is lost as discarded carbon and required for cracking of methane and Hquefaction of hydrogen. 

Ya and ZP prepared carbon molecular sieves from cheap condensed petroleum cokes. The cokes were impregnated with potassium hydroxide and the resulting activated carbon micropore system was modified by cracking of methane or liquefied petroleum gas. The activation of the coke with potassium hydroxide produced high surface area activated carbons with pores of 0.85 nm average diameter. This pore diameter was reduced to between 0.58 and 0.33 nm on deposition of carbon, and the miCTOpore volume remained almost unchanged. 

---