Carbon, filamentous

Pyrolysis of methane under the action of pulsed microwave radiation in the presence of solid catalysts has been reported by Russian authors [71, 72], The application of pulse microwave power was shown to be a promising means of production of hydrogen syngas, ethyne, and filament carbon. 

A series of kinetic studies on the carbon filament formation by methane decomposition over Ni catalysts was reported by Snoeck et al. [116]. The authors derived a rigorous kinetic model for the formation of the filamentous carbon and hydrogen by methane cracking. The model includes the following steps ... 

The rigorous kinetic modeling with the incorporation of the diffusion step allows explaining the deactivation of the carbon filament growth and the influence of the affinity for carbon formation on the nucleation of the filamentous carbon. 

Ermakova, M. and Ermakov, D., Ni/SiOz and Fe/Si02 catalysts for production of hydrogen and filamentous carbon via methane decomposition, Catal. Today, 77, 225, 2002. 

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

Carbon Precipitation (4 Filamentous Carbon and Deposition Formation... 

ASTM D4018-81 standard test method for tensile properties of continuous filament carbon and graphite yams, strands, roving, and tow... 

Filamentous carbon Type of carbon that grows in long filaments or tubular structures on the inner walls of metal surfaces. 

Of particular interest are catalytic methane decomposition reactions producing special (e.g. filamentous) forms of carbon. For example, researchers have reported catalytic decomposition of methane over Ni catalyst at 500°C with the production of hydrogen and whisker carbon26 and concentrated solar radiation was used to thermally decompose methane into hydrogen and filamentous carbon.27 The advantages of this system included efficient heat transfer due to direct irradiation of the catalyst, and C02-free operation. 

The growth of filamentous carbon along with the gas phase product analysis has been used to determine the influence of sulfur on the iron catalyzed decomposition of carbon containing gas mixtures at 600°C. Pretreatment of the metal in H2S was found to initially suppress the reactions leading to carbon deposition from the decomposition of CO/H2 mixtures. After a short time the activity was restored to approximately the same level as that exhibited by an unadulterated iron powder, suggesting that most of the sulfur atoms were being removed from the surface. The small residual fraction of adatoms did, however, induce modifications in the structural characteristics of the filamentous carbon deposit and also altered the reactivity pattern of the iron towards decomposition of a CO/C2H4/H2 mixture. 

W. Holstein, The roles of ordinary and soret diffusion in the metal-catalysed formation of filamentous carbon,/. Catal. 152, 42-51 (1995). 

Figure 12. Carbon deposition on metal particles as a function of metal temperature. The dominating form is filamentous carbon, and more conventional forms occur in sizeable quantities only in extremely high-temperature catalytic processes. (After [24]).

Polycrystalline Amorphous Epitaxial silicon Carbon fiber Filaments Carbon nanotubes Silicon dioxide Tungsten Silicon nitride Titanium nitride... 

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