Effects of Precursors and Plasma Parameters on Fullerene Synthesis in RF Thermal Plasma Reactor

Abstract

Synthesis of fullerenes from graphite powders of different grade was studied in a radiofrequency (RF) plasma reactor. Dependence of fullerene yield on the properties and feed rate of precursors and on the helium content of plasma gas was studied in details. The fullerene yield was influenced by the mean size and the thermal conductivity of graphite particles on the one hand, and the helium content of the gas phase on the other. Soot containing fullerene mixture of 5.9% was produced in best conditions found in this work. The main component of the fullerene mixture was C 60 . In addition, it contained about 30% of C 70 (corresponding to a C 60 /C 70 mass

Modeling of Induction Plasma Process for Fullerene Synthesis: Effect of Plasma Gas Composition and Operating Pressure

“…Recently, it has been demonstrated that large-scale production of fullerenes is feasible by evaporating carbon-containing materials in RF induction thermal plasma reactors [11][12][13][14][15][16][17][18][19] (see Fig. 1).…”

“…Cota-Sanchez et al [15] extensively explored a fullerene synthesis process by an RF plasma jet (2)(3)(4)(5) to investigate the effect of the operating parameters on the fullerene formation, e.g., operating pressure, plate power, and carbon feed rate. Todorovic-Markovic et al reported the dependence of the fullerene yield on the properties of the graphite powder, e.g., mean aggregate size and thermal conductivity, as well as on the helium content in the plasma gas [17][18][19]. In order to investigate the influence of the plasma forming gas and operating pressure on the fullerene synthesis in an RF plasma process, Wang et al [11] developed a two-dimensional (2-D) model without considering the carbon particle injection.…”

“…In fact, many of the speculations and interpretations suggested by researchers are in conflict with each other. For example, the higher yield rate of fullerenes as the helium content increases in the plasma gas was mainly explained by the fast evaporation of feedstock materials due to its good thermal conductivity [17], but it was deduced by Wang et al [11] that a sharp temperature gradient along the central axis observed in the helium plasma is mainly responsible for the effective formation of fullerenes. Based on this argument, Wang et al [11] further claimed that low operating pressures would promote the formation of fullerenes because a higher axial velocity obtained by the fast expansion of plasma gas can increase the temperature gradients experienced by fullerenes precursors.…”

Effect of the solid precursors on the formation of nanosized TiBx powders in RF thermal plasma

“…The argon and the helium were of 4.6 purity. Selection of working parameters was based on tests for the synthesis of nanoparticles using the same technique [9][10][11][12][13]27]. Helium was added both to the plasma and the carrier gas because of its high thermal conductivity and enthalpy, compared to other inert gases [11].…”

“…Titanium diboride (TiB 2 ) is a non-oxide refractory ceramic material with excellent properties such as high melting point (3225 °C), high hardness (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35), high thermal (60-120 W/(m K)) and electrical conductivity (~10 5 S/cm), resistance to mechanical erosion and chemical corrosion. This combination of properties makes TiB 2 a candidate for high performance applications including wear resistant parts, metal melting crucibles, composite and electrode materials [1,2].…”