Nanotube synthesis methods catalytic

Since the synthesis of carbon nanotubes by Iijima [1, 2], a lot of investigations have been made on this kind of novel material [3-16]. Carbon nanotubes can be conventionally synthesized with several methods [17, 18], Recently, catalytic synthesis method has been developed to prepare carbon nanotubes on Co/Si02 [19, 20]. Hemadi et al. first extended the catalytic synthesis to the use of zeolites (NaY, HY and ZSM-5) as catalyst supports to synthesize carbon nanotubes [21]. 

Among the various experimental parameters, the choice of catalytic additives is of paramount importance. In the first place, the characteristic feature that is common to all SWNT synthesis methods is the participation of a catalyst. So far, no SWNT has been synthesized without the participation of a catalyst. From the pioneering work of lijima (3) it was recognized that the use of Ni, Fe, Co, or their mixtures influenced the shape, yield, and perhaps location of the nanotube-containing products. In more recent studies, important differences in SWNT yield and selectivity have been observed when the metals were varied (49). From the very first investigations, researchers... 

Carbon nanotubes synthesized by the catalytic route exhibit a less well-defined graphene structure compared to those formed by the arc-discharge method due to the low synthesis temperature. This can be rectified by submitting these nanotubes to a high temperature treatment in the range of 1800 to 2600 °C under an inert atmosphere. The heat-treated carbon nanotubes exhibit a more ordered graphene structure compared to their counterpart obtained after the low-temperature synthesis via catalytic route (Fig. 7.10A and B). 

CVD is a general method for the commercial production of carbon nanotubes. For this idea, the metal nanoparticles are mixed with a catalyst support such as MgO or AI2O3 to enhance the surface area for higher revenue of the catalytic reaction of the carbon feedstock with the metal particles. One matter in this synthesis method is the removal of the catalyst support via an acid treatment, which sometimes could destroy the primary structure of the carbon nanotubes. However, other catalyst supports that are soluble in water have verified effective for nanotube development. 

The primary synthesis methods for single and multi-walled carbon nanotubes include arc-discharge [203, 204], lase ablation [205], gas-phase catalytic growth from carbon monoxide [206], and chemical vapor deposition (CVD) from hydrocarbons [207-209], The scale-up limitation of arc discharge and laser ablation methods would make them cost prohibitive. One unique aspect of CVD technique is its ability to synthesize aligned arrays of carbon nanotubes with controlled diameter and length. The details on these methods go beyond the scope of this chapter. 

Single-walled nanotubes purified from Meijo University at Nagoya (SWNTs). These nanotubes were synthesized by electric arc discharge (iron was used as catalytic particles) and then purified by annealing at 693 K and a mild hydrochloric acid treatment [1(X)]. Double-walled nanotubes (DWNTs) synthesized by CVD at CIRIMAT at Toulouse University. These nanotubes were synthesized by the CVD process. Catalytic nanoparticles are formed from solid solutions of Mgi cCO cMOj,0. The synthesis method used is the same as that described by Bacsa et al. [101] but with small differences in the catalytic nanoparticles synthesis. 

New spatial forms of carbon - fullerenes, nanotubes, nanowires and nanofibers attract significant interest since the time of their discovery due to their unique physicochemical and mechanical properties [1-3]. There are three basic methods of manufacturing of the carbon nanomaterials (CNM) - laser evaporation, electric arc process, and catalytic pyrolysis of hydrocarbons. However, the multi-stage manufacturing process is a serious disadvantage for all of them. For example, the use of organic solvents (benzol, toluene, etc.) for separation of fullerenes from graphite soot results in delay of the synthesis process and decrease in the final product quantity. Moreover, some environmental problems can arise at this. 

Now, the use of both the EW and SE methods provides a possibility to manufacture novel CNM - fullerenes, nanotubes, etc. In this case we can reach the conclusion, that CNM are produced under very non-equilibrium conditions, namely under conditions of the high-energy plasmochemistry synthesis in organic mediums. At this conjuncture intensive flows and extreme densities of matters occur. It results in production of CNM due to self-organization and directional catalytic transformations. 

Abstract. Nanocarbon materials and method of their production, developed by TMSpetsmash Ltd. (Kyiv, Ukraine), are reviewed. Multiwall carbon nanotubes with surface area 200-500 m2/g are produced in industrial scale with use of CVD method. Ethylene is used as a source of carbon and Fe-Mo-Al- mixed oxides as catalysts. Fumed silica is used as a pseudo-liquid diluent in order to decrease aggregation of nanotubes and bulk density of the products. Porous carbon nanofibers with surface area near 300-500 m2/g are produced from acetylene with use of (Fe, Co, Sn)/C/Al203-Si02 catalysts prepared mechanochemically. High surface area microporous nanocarbon materials were prepared by activation of carbon nanofibers. Effective surface area of these nanomaterials reaches 4000-6000 m2/g (by argon desorption method). Such materials are prospective for electrochemical applications. Methods of catalysts synthesis for CVD of nanocarbon materials and mechanisms of catalytic CVD are discussed. 

An exhaustive study has been carried out recently on the synthesis of BN nanotubes and nanowires by various CVD techniques.17 The methods examined include heating boric acid with activated carbon, multi-walled carbon nanotubes, catalytic iron particles or a mixture of activated carbon and iron particles, in the presence of ammonia. With activated carbon, BN nanowires are obtained as the primary product. However, with multi-walled carbon tubes, high yields of pure BN nanotubes are obtained as the major product. BN nanotubes with different structures were obtained on heating boric acid and iron particles in the presence of NH3. Aligned BN nanotubes are obtained when aligned multi-walled nanotubes are used as the templates (Fig. 40). Prior to this report, alignment of BN nanotubes was achieved by the synthesis of the BN nanotubule composites in the pores of the anodic alumina oxide, by the decomposition of 2,4,6-trichloroborazine at 750 °C.116 Attempts had been made earlier to align BN nanotubes by... 

We have developed solvothermal synthesis as an important method in research of metastable structures. In the benzene-thermal synthesis of nanocrystalline GaN at 280°C through the metathesis reaction of GaClj and U3N, the ultrahigh pressure rocksalt type GaN metastable phase, which was previously prepared at 37 GPa, was obtained at ambient condition [5]. Diamond crystallites were prepared from catalytic reduction of CCI4 by metallic sodium in an autoclave at 700°C (Fig.l) [6]. In our recent studies, diamond was also prepared via the solvothermal process. In the solvothermal catalytic metathesis reaction of carbides of transition metals and CX4 (X = F, Cl, Br) at 600-700°C, Raman spectrum of the prepared sample shows a sharp peak at 1330 cm" (Fig. 1), indicating existence of diamond. In another process, multiwalled carbon nanotubes were synthesized at 350°C by the solvothermal catalytic reaction of CgCle with metallic potassium (Fig. 2) [7]. 

Exhaustive studies have been carried out on the synthesis of BN nanotubes and nanowires by various CVD techniques [225]. The methods examined include heating boric acid with activated carbon, multi-walled carbon nanotubes, catalytic iron particles or a mixture of activated carbon and iron particles, in the presence of ammonia. With activated carbon, BN nanowires are obtained as the primary prod-... 

Synthesis of one dimensional, two dimensional and three dimensional nanostructured metal oxides have attracted a great deal of interest for the past many years. Because of their size dependent catalytic and optoelectronic properties, they can be broadly tuned through size variation. Recently, extensive efforts have been made to synthesize one dimensional metal oxides nanostructures such as nanowires, nanobelts, nanotubes, nanorods, nanorings etc [Fig.2], Various methods have been used in literature for development of nanostructured metal oxides of varying shape and sizes are as follows. 

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