Catalytic carbon deposition CCVD

Multiwall carbon nanotubes (MWCNTs) have been synthesized by catalytic chemical vapor deposition (CCVD) of ethylene on several mesoporous aluminosilicates impregnated with iron. The aluminosilicates were synthesized by sol-gel method optimizing the Si/Al ratios from 6 to 80. The catalysts are characterized by nitrogen adsorption, X-ray diffraction, 27A1 NMR, thermogravimetric analysis (TGA) and infrared. The MWCNTs are characterized by TGA and transmission and scanning electron microscope. 

Review on Catalytic Chemical Vapour Deposition (CCVD) Growth of Single Walled Carbon Nanotubes and their Characterization... 

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. 

VAPOR-GROWN CARBON FIBERS (VGCF) AND CATALYTIC CHEMICAL VAPOR-DEPOSITED (CCVD) FILAMENTS... 

Synthesis of CNT over oxides supports by Catalytic Chemical Vapor Deposition (CCVD) is one of the most important techniques for mass production of non-aligned CNT. It could be useful for the production of composite materials, field emission sources, fuel cells, supercapacitors among others technological applications. The CCVD method consists on the decomposition of a gas or a liquid precursor, which supplies carbon to the surface of the catalytic particles (e.g. Fe) in a tube furnace at temperatures around 900 °C. This technique is scalable for mass production at lower temperatures and could be adapted for continuous production. 

The catalytic chemical vapor deposition (CCVD) technique is far more developed and has great potential to be applied industrially. This technique allows for mass production at lower temperatures than the previously described methods and can be adapted for continuous production [69]. This method consists of decomposing a gas or a liquid precursor, which supplies carbon on catalytic particles (Fe, Ni, Co) in a mbe furnace at temperatures between 500 and 1,100 °C (Fig. 5.4). Besides the classic oven, heated by electric heaters, plasma furnaces (PECVD, Plasma-Enhanced Chemical Vapor Deposition) microwaves (nuCTowave, MW-PECVD), or DC (direct current, dc-PECVD) are also used. 

Colomer JF, Stephan C, Lefrant S, Tendeloo GV, Willems 1, Kanya Z, et al. Large-scale synthesis of single-wall carbon nanotubes by catalytic chemical vapor deposition CCVD method. Chem Phys Lett 2000 317 83-9. 

Mukhopadhyay K, Koshio A, Sugai T, Tanaka N, Shinohara H, Konya Z, et al. Bulk production of quasi-ahgned carbon nanotube bundles by the catalytic chemical vapour deposition (CCVD) method. Chem Phys Lett 1999 303 117-24. 

Since their discovery by Ijima in the early nineties as a byproduct of fullerene synthesis [1], carbon nanotubes have received a growing interest. A huge number of synthesis routes have been proposed, ranging from laser ablation of carbon target, catalytic chemical vapour deposition (CCVD), liquid phase synthesis, plasma methods, and so forth [2]. Also, a large variety of application niches have been identified that render nanotubes a promising material [3]. 

A floating catalyst method, which has been used for the large-scale production of carbon nanotubes, was applied in the synthesis of double-walled BNNTs by Kim et al." Borazine was chosen as the precursor for BN formation because of its chemical composition (1 1 B/N ratio) and high volatility. In this catalytic chemical vapor deposition (CCVD) technique, a mixture of ammonia and nitrogen gas (in a flow ratio of 100 3 sscm), borazine vapor along with a nickelocene catalyst flowed... 

Carbon nanotubes can be synthesized by different techniques including arc-discharge [58,59], laser ablation [60-63] and various catalytic chemical vapor depositions (CCVD) [64-67]. 

The term vapor grown carbon fiber (VGCF) is an International Union of Pure and Applied Chemistry (lUPAC) recommendation and Tibbetts [1] believes that this term has won general acceptance for the class of material where a carbonaceous gas, in the presence of a small metal particle acting as a catalyst, forms a carbon filament. However, Dresselhaus and co-authors [2] use the term CCVD filament in their book, which stands for catalytic chemical vapor deposition and is certainly more descriptive of their mode of preparation, but is, unfortunately, not the generally accepted term. 

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