Catalytic decomposition of hydrocarbon

During the last years, several authors have reported the production of carbon nanotubes by the catalytic decomposition of hydrocarbons in the presence of metals[l-5]. More recently, carbon nanotubes were also found as by-products of arc-discharge[6] and hydrocarbon flame[7] production of fullerenes. 

Fig. 4. Schematic drawing of the apparatus used for the catalytic decomposition of hydrocarbon.

MWCNT synthesized by catalytic decomposition of hydrocarbon does not contain nanoparticle nor amorphous carbon and hence this method is suitable for mass production. The shape of MWCNT thus produced, however, is not straight more often than that synthesized by arc-discharge method. This differenee could be aseribed to the strueture without pentagons nor heptagons in graphene sheet of the MWCNT synthesized by the catalytic decomposition of hydrocarbon, which would affect its electric conductivity and electron emission. 

Fe, Co or Ni is also crucial in the catalytic decomposition of hydrocarbon. In order to efficiently obtain CNT and to control its shape, it is necessary and indispensable to have enough information on chemical interaction between carbon and these metals. It is quite easy for the catalytic synthesis method to scale up the CNT production (see Chap. 12). In this sense, this method is considered to have the best possibility for mass produetion. It is important to further improve the process of catalytie synthesis and, in order to do so, clarifieation of the mechanism of CNT growth is necessary to control the synthesis. CNT can be synthesized by the chemical reaction at relatively low... 

Chesnokov, V.V., and Buyanov, R.A. (2000) Formation of carbon strings at catalytic decomposition of hydrocarbons on metals of a subgroup of iron and their alloys, Uspekhi khimii, 69, No 7, 675-692 (in Russian). 

In the course of IR pyrolysis, according to mass spectrometry and gas chromatography data, various gas products of destruction of PAN polymeric chain are present in the reaction chamber, including hydrocarbons such as ethylene and propylene [17, 18], These hydrocarbons provide the carbon source. Catalytic decompositions of hydrocarbons at high intensity IR-radiation in the presence of metallic Gd leads to the formation of carbon nanostructures such as observed bamboo-like CNT. It is well known that Ni, Co Fe have conventionally been used widely as metallic catalysts for high temperature pyrolysis of hydrocarbons. Recently bimetallic components was shown to be more effective than single metals as catalysts. Especially transition metals with addition of rare-earth metals such as Y, Ce, Tb, La and Ho [19]. In this work catalytic activity of single metallic Gd in the IR-pyrolysis of hydrocarbons are found by us for the first time. 

The synthesis of CNTs is reeeiving considerable interest and the main goal is to obtain large scale produetion of highly pure CNTs. There are three basic methods for synthesis of SWCNTs and MWCNTs eleetrical arch discharge, laser ablation (laser vaporization) and ehemical vapor deposition (CVD) (or catalytic decomposition of hydrocarbons) [1,7, 9,10, 25,26],... 

C.2. Detecting Hydroxyl Radicals in the Microwave-assisted Photo catalytic Decomposition of Hydrocarbons... 

Since zeolites are typical acid-base catalysts, their acid-base properties are of great importance in investigating the catalytic decomposition of hydrocarbons. Three methods — titration, temperature-programmed desorption, and characterization by test reaction — are employed to measure acid-base properties. In this study, n-hexane was used as a model hydrocarbon and its decomposition over HY, HCeY, HSmY, and HCuY zeolites was investigated. Depending on the metal exchanged, n-hexane conversion and product distribution were observed to vary in the higher ccmversion r ion. The relation between product distribution and the acid-base properties of the zeolites are discussed. 

Derivation (1) Reaction of steam with natural gas (steam reforming) and subsequent purification (2) partial oxidation of hydrocarbons to carbon monoxide and interaction of carbon monoxide and steam (3) gasification of coal (see Note 1) (4) dissociation of ammonia (5) thermal or catalytic decomposition of hydrocarbon gases (6) catalytic reforming of naphtha (7) reaction of iron and steam (8) catalytic reaction of methanol and steam (9) electrolysis of water (see Note 2). In view of the importance of hydrogen as a major energy source of the future, development of the most promising of these methods may be expected. 

Large scale synthesis of carbon nanofibers by catalytic decomposition of hydrocarbon... 

In recent years a new type of carbon nanostructure has been synthesized from catalytic decomposition of hydrocarbons. These fibrous materials are graphitic nanofibers (GNFs). 

The catalytic decomposition of carbon-contaming compounds is an extensively investigated method, also known as catalytic chemical vapor deposition (CCVD). One of the advantages of this method is the potential for large-scale production at a lower energy consumption and overall cost than with other methods. The CCVD method is essentially the same as that used for a long time in the synthesis of other filamentous forms of carbon, such as nanofibers or fibrils. The CCVD method involves the catalytic decomposition of hydrocarbons or carbon monoxide on transition metal particles. The major difference with those processes that produce nanofibers is in the structure of the catalyst. To produce SWNT, the size of the metal cluster needs to be very small. Therefore, the success of a CCVD method lies in the design of the catalyst. 

J F Colomer, Syntfaesis of sii le-wall carbon nanotubes by catalytic decomposition of hydrocarbons , Chem. Conmun, 1999. 

Gierak, A. and Leboda, R. 1989. Preparation of carbonaceous adsorbents by catalytic decomposition of hydrocarbons for chromatographic applications. J. Chromatogr. 483 197-207. 

Carbon fibers are also produced from the catalytic decomposition of hydrocarbon gases. These vapor-grown fibers can be prodnced at snbmicrometer diameters and show great potential in battery applications. Larger vapor-grown fibers can be produced rapidly by pulse injection and show promise as filler material in composites. 

Carbon nanotubes have been formed by many different methods, eight having been reviewed by Joumet and Bernier (1998). Two of them have been studied extensively catalytic decomposition of hydrocarbons and CO, and vaporization... 

A closely related type of material to MWNT is graphite nanofibers (GNF), developed by Baker and Rodriguez (Rodriguez et al., 1995). GNF are prepared by catalytic decomposition of hydrocarbons on metals or metal alloys at temperamres... 

Cheng, H.M. Li, F. Sun, X. Brown, S.D.M Pimenta, M.A. Marucci, A. Dresselhaus, G. Dresselhaus, M.S. (1998). Bulk morphology and diameter distribution of single-walled carbon nanotubes synthesized by catalytic decomposition of hydrocarbons. Chemical Physics Letters, 289,602-610. 

MWCNTs can be prepared by two distinct methods catalytic decomposition of hydrocarbons such as acefylene, ethylene, or camphor vapor, or an electric arc technique. 

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