Fullerene Production

The standard method to synthesize MWCNTs is based on the electric-arc experiment proposed by Ebbesen and Ajayan [8]. Basically, the production system is similar to the one used by Kratschmer et al. [11] to produce macroscopic quantities of C o and the main difference between the two experiments is the inert gas pressure, that must be rather low (20-100 mbar) for an efficient fullerene production [11], but must be increased to 350-700 mbar to generate nanotubes efficiently [8],... 

Lamb LD, Huffman DR (1993) Fullerene production. Journal of Physics and Chemistry of Solids 54 1635-1643. 

Continuous production of fullerenes was possible by pyrolysis of acetylene vapor in a radio-frequency induction heated cylinder of glassy polymeric carbon having multiple holes through which the gas mixture passes [44]. Fullerene production is seen at temperatures not exceeding 1500 K. The yield of fullerenes, however, generated by this method is less than 1%. A more efficient synthesis (up to 4.1% yield) was carried out in an inductively coupled radio-frequency thermal plasma reactor [45]. 

Takehara H, Fujiwara M, Arikawa M et al (2005) Experimental study of industrial scale fullerene production by combustion synthesis. Carbon 43 311-319... 

Alford JM, Bernal C, Cates M et al (2008) Fullerene production in sooting flames from 1,2,3,4-tetrahydronaphthalene. Carbon 46 1623-1625... 

Murayama H, Tomonoh S, Alford JM et al (2004) Fullerene production in tons and more from science to industry. Fullerenes, Nanotubes, Carbon Nanostruct 12 1-9... 

Fulcheri L, Schwob Y, Fabry F et al (2000) Fullerene production in a 3-phase AC plasma process. Carbon 38 797-803... 

Abstract Plasma polymerization is a technique for modifying the surface characteristics of fillers and curatives for rubber from essentially polar to nonpolar. Acetylene, thiophene, and pyrrole are employed to modify silica and carbon black reinforcing fillers. Silica is easy to modify because its surface contains siloxane and silanol species. On carbon black, only a limited amount of plasma deposition takes place, due to its nonreactive nature. Oxidized gas blacks, with larger oxygen functionality, and particularly carbon black left over from fullerene production, show substantial plasma deposition. Also, carbon/silica dual-phase fillers react well because the silica content is reactive. Elemental sulfur, the well-known vulcanization agent for rubbers, can also be modified reasonably well. 

Application of a plasma coating onto carbon black is very difficult compared to silica. It was only practically feasible for fullerene soot (left over from the fullerene production), which contains a large amount of reactive groups on its surface. Polyacetylene-plasma-treated fullerene soot provides an improved dispersion in SBR and in a SBR/EPDM blend compared to untreated fullerene black. However, the effect on the stress-strain properties is rather limited and the coating has only a slight effect on the final properties. 

NMA+) and 2,4,6-triphenyl-pyrylium tetrafluoroborate (TPP+) in the presence of biphenyl as cosensitizer were suitable for this reaction [174], The assumed mechanism of formation of do by this cosensitization is shown in Scheme 7. Reaction of do with H-donors such as te/t-butylmethylether, propionaldehyde and alcohols results in the formation of 1 1 adducts, the 1-substituted 1,2-dihydro-[60]fullerenes. Product structure support a H-abstraction process [212,213] rather than nucleophilic addition. In Scheme 8, the general formation of 1-substituted l,2-dihydro-[60]fullerenes is shown. Selected examples of the products obtained by this method are summarized in Table 10. 

On the Fig. 1 the graphs of the obtained dependencies are shown. One can see that soot, fullerenes and re-crystallized graphite are formed in all cases, and their yields depend on both current value and current type. Re-crystallized graphite is a byproduct of the fullerene synthesis which decreases the fullerene productivity and efficiency. It was established that the optimal regime of fullerene synthesis occurs at 44 kHz AC and 200 A. Under these conditions, a fullerene production rate of 16mg/min at a fullerene yield of 9% was obtained while the yield of re-crystallized graphite (7%) was minimal. 

Figure 1. Dependencies of basic setup characteristics on arc current value for DC, AC 50 Hz, and AC 44 kHz 1 - soot yield 2 - recrystalized graphite (RG) yield 3 - electrodes erosion rate 4 - fixllerene yield 5 - fullerene production rate.

Fullerene production rate, mg/min Fullerene production rate, mg/min Fullerene production rate, mg/min... 

The basic characteristics of devices for fullerene synthesis at atmospheric pressure were investigated. It was observed that the maximum fullerene production rate (16 mg/min) was obtained in arcs fed by AC of 44 kHz and 200 A. Under these conditions the amount of deposited re-crystallized graphite was minimal, and practically all evaporated carbon was transformed into soot containing 9% of fullerenes. 

The other method of amorphous fullerenes production -the ball milling amorphisation - was investigated. Samples of amorphous fullerenes were produced by application of the mechano-activation treatment (milling in a ball mill) and their structure (Fig. 6) and sorption properties were investigated. 

Baierl, T., et al. (1996), Comparison of immunological effects of fullerene C60 and raw soot from fullerene production on alveolar macrophages and macrophage like cells in vitro, Exp. Toxicol. Pathol., 48, 508-511. 

While in theory fullerene-like structures can be made up for any even number of carbon atoms (except for 22), the classical methods of fullerene production do... 

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