Carbonaceous particle synthesis

Apart from manifold structures, carbons can have various shapes, forms, and textures, including powders with different particle size distributions, foams, whiskers, foils, felts, papers, fibers [76, 77], spherical particles [76] such as mesocarbon microbeads (MCMB s) [78], etc. Comprehensive overviews are given, for example in [67, 71, 72], Further information on the synthesis and structures of carbonaceous materials can be found in [67, 70, 72, 75, 79]. Details of the surface composition and surface chemistry of carbons are reviewed in Chapter II, Sec. 8, and in Chapter III, Sec. 6, of this handbook. Some aspects of surface chemistry of lithiated carbons will also be discussed in Sec. 5.2.2.3. 

The underlying concept of this method for the synthesis of filamentous carbonaceous nanomaterials is fairly simple. As the temperature rises above a certain limit, which depends on the thermodynamic and kinetic para meters of carbon containing compounds, such as hydrocarbons, such compounds tend to pyrolyze in the air free conditions to form free carbon. For example, the noncatalytic pyrolysis of methane can be achieved at ambient pressure and at temperatures above 900—1000 K to produce soot (near spherical nanosized carbon particles) and hydrogen ... 

The major difficulty of this process arose from the physically and chemically unstable catalyst. The ircm particles broke down in size very rapidly under the synthesis conditions. The fluffy nature of the product made fluidizaticm difficult, if not impossible. Also, catalyst particles were waxed up, i.e., coated with carbonaceous materials, and activity decreased significantly (S22). 

The micro-Znanostructure of the carbon component of the CS surface seems to be close to that of carbon black particles since the conditions of their synthesis are similar in many aspects. However, as distinct from carbon black particles the size of carbonaceous deposits at a matrix surface is determined to a great extent by the nature and porosity of a substrate and sizes of its particles. Therefore, the morphology and the texture of carbons in CS may considerably differ from that of carbon blacks (Gun ko and Leboda 2002, Gun ko et al. 2002c). 

Organic-rich extraterrestrial samples such as meteorites, micrometeorites, interplanetary dust particles (IDPs) and samples returned by spacecraft provide a unique record of the chemical processes in the early solar system and in the interstellar medium. In particular, detailed structural and isotopic analyses of carbonaceous meteorites have revealed a rich organic inventory and provided evidence of the synthesis of complex organic molecules in the interstellar medium and on the asteroidal parent bodies of meteorites [1,2], The organic matter in carbonaceous meteorites is present at levels of up to 5% and can be divided into solvent-soluble (l%-25%) and insoluble (75%-99%) fractions, the former characterized by considerable structural, isomeric, and isotopic diversity [2,3], and the latter characterized by a high molecular weight and complex aromatic network [4]. 

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