Formation of fullerenes in highly concentrated solar flux

Fields, C. L.; Pitts, Jennifer; Hale, Mary Jane; Bingham, Carl; Lewandowski, A.; King, David E.

doi:10.1021/j100136a008

Cited by 76 publications

(22 citation statements)

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“…Other methods of fullerene synthesis include ion sputtering and electron beam evaporation of graphite [16], vaporization of graphite using highly concentrated solar heating [17,18], resistive heating of graphite [19], laser ablation of graphite [5,20], inductive heating of graphite [21], and carbon particle evaporation in a hybrid thermal plasma [22]. Several production methods using non-graphitic raw materials have also been studied and found to produce fullerenes.…”

Section: Formation Offullerenes and Nanostructuresmentioning

confidence: 99%

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Combustion synthesis of fullerenes and fullerenic nanostructures

Goel

Hebgen

Sande

et al. 2002

Carbon

117

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Fullerenes are molecules comprised entirely of sp 2 -bonded carbon atoms arranged in pentagonal and hexagonal rings to form a hollow, closed-cage structure. Buckyballs, a subset which contains C 60 and C 70 , are single-shell molecules while fullerenic nanostructures can contain many shells and over 300 carbon atoms. Both fullerenes and nanostructures have an array of applications in a wide variety of fields, including medical and consumer products. Fullerenes were discovered in 1985 and were first isolated from the products of a laminar low-pressure premixed benzene/oxygen/argon flame operating at fuel-rich conditions in 1991. Flame studies indicated that fullerene yields depend on operating parameters such as temperature, pressure, residence time, and equivalence ratio. High-resolution transmission electron microscopy (HRTEM) showed that the soot contains nanostructures, including onions and nanotubes.Although flame conditions for forming fullerenes have been identified, the process has not been optimized and many flame environments of potential interest are unstudied. Mechanistic characteristics of fullerene formation remain poorly understood and cost estimation of large-scale production has not been performed. Accordingly, this work focused on: 1) studying fullerene formation in diffusion and premixed flames under new conditions to identify optimal parameters; 2) investigating the reaction of fullerenes with soot; 3) positively identifying C 60 molecules in HRTEM by tethering them to carbon black; and 4) providing a cost estimation for industrial fullerenic soot production.Samples of condensable material from laminar low-pressure benzene/argon/oxygen diffusion flames were collected and analyzed by high-performance liquid chromatography (HPLC) and HRTEM. The highest concentration of fullerenes in a flame was always detected just above the height where the fuel is consumed. The percentage of fullerenes in condensable material increases with decreasing pressure and the fullerene content of flames with similar cold gas velocities shows a strong dependence on length. A shorter flame, resulting from higher dilution or lower pressure, favors the formation of fullerenes rather than soot, exhibited by the lower amount of soot and precursors in such flames. This indicates a stronger correlation of fullerene consumption to soot levels than of fullerene formation to precursor concentration. The maximum flame temperature seems to be of minor importance in formation. The overall highest amount of fullerenes was found for a surprisingly high dilution of fuel with argon. The HRTEM analysis showed an increase of the curvature of the carbon layers, and hence increased fullerenic character, with increasing distance from the burner up to the point of maximum fullerene concentration, after which it decreases, consistent with the HPLC analysis. The soot shows highly ordered regions that appear to have been cells of fullerenic nanostructure formation. The samples also included fullerenic nanostructures such as tubes and sp...

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Section: Formation Offullerenes and Nanostructuresmentioning

confidence: 99%

“…The top plate, shown schematically in Figure 3-8, consists of a stainless steel disc (18 in. x / 2 in) that seals the chamber and contains three 1 /2-in.diameter access ports.…”

Section: Top Platementioning

confidence: 99%

Combustion synthesis of fullerenes and fullerenic nanostructures

Goel

Hebgen

Sande

et al. 2002

Carbon

117

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“…Some groups [32][33][34][35][36][37][38][39] have demonstrated that fullerenes can be produced using highly concentrated sunlight from a solar furnace. This method, which can be compared with the laser ablation one, uses a solar furnace to focus the sunlight on a graphite sample and vaporize carbon.…”

Section: Solar Energymentioning

confidence: 99%

Production of carbon nanotubes

Journet¹,

Bernier²

1998

Applied Physics A: Materials Science & Processing

327

115

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Carbon nanostructures such as single-walled and multi-walled nanotubes (SWNTs and MWNTs) or graphitic polyhedral nanoparticles can be produced using various methods. Most of them are based on the sublimation of carbon under an inert atmosphere, such as the electric arc discharge process, the laser ablation method, or the solar technique. But chemical methods can also be used to synthesize these kinds of carbon materials: the catalytic decomposition of hydrocarbons, the production by electrolysis, the heat treatment of a polymer, the low temperature solid pyrolysis, or the in situ catalysis.

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“…This particular feature of solar furnaces projects them as a potential tool for the materials processing. Some examples of the synthesis of materials with concentrated solar energy are: synthesis of fullerenes [5][6][7][8][9]; synthesis of tungsten carbide [10][11][12]; synthesis of molybdenum carbide [13]; synthesis of calcium carbide [14]; and processing of silicon carbide [15][16][17][18]. The main disadvantages of solar processes are the intermittent nature of solar energy and the initial investment costs of solar systems.…”

Section: Introductionmentioning

confidence: 99%

Solar production of WO3: a green approach

Villafán-Vidales

Jiménez-González

Bautista-Orozco

et al. 2015

Green Processing and Synthesis

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Abstract:The tungsten trioxide (WO 3 ) is a promising material with important technologic and scientific applications, due to its electrochromic, gasochromic and photochromic properties. Usually, this material is synthesized following several routes, for example, sputtering, chemical deposition, sol-gel, hydrothermal, among others. However, these methods are complicated, have long processing times and use several chemicals with the possibility of keeping undesirable impurities. In this context, concentrated solar energy is an interesting and feasible option to process materials at a low cost and without greenhouse gas emissions. In this work, a simple and green synthesis method of WO 3 by using the Solar Furnace of the Renewable Energy Institute of the National University of Mexico is presented. Tungsten oxide powder is obtained by means of tungsten electrodes in a high-temperature solar reaction chamber designed to work with concentrated solar energy under controlled conditions of the gas atmosphere. The oxidation reaction was carried out for three different temperatures: 600°C, 800°C and 1000°C, and for each temperature three different oxygen molar fractions were studied: 0.33, 0.41 and 1. Some results indicate the oxygen molar fraction does not affect the phase transformation and the WO 3 triclinic was the most stable phase, appearing in all the temperature ranges and concentrations. The synthesis reported in this paper is presented as a green alternative in the development of processes for the synthesis of WO 3 , which promote renewable energy sources with very low greenhouse gas emissions and without toxic residuals.

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Formation of fullerenes in highly concentrated solar flux

Cited by 76 publications

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Combustion synthesis of fullerenes and fullerenic nanostructures

Combustion synthesis of fullerenes and fullerenic nanostructures

Production of carbon nanotubes

Solar production of WO3: a green approach

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