WO2005068067A1 - Appareil a arc electrique destine a fabriquer des fullerenes - Google Patents

Appareil a arc electrique destine a fabriquer des fullerenes Download PDF

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WO2005068067A1
WO2005068067A1 PCT/US2004/006886 US2004006886W WO2005068067A1 WO 2005068067 A1 WO2005068067 A1 WO 2005068067A1 US 2004006886 W US2004006886 W US 2004006886W WO 2005068067 A1 WO2005068067 A1 WO 2005068067A1
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anode
cathode
reactor chamber
carbon
fullerenes
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Michael Joseph Pepka
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Michael Joseph Pepka
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/087—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J19/088—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/152—Fullerenes
    • C01B32/154—Preparation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/158—Carbon nanotubes
    • C01B32/16—Preparation
    • C01B32/162—Preparation characterised by catalysts
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/18—Nanoonions; Nanoscrolls; Nanohorns; Nanocones; Nanowalls
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0809—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes employing two or more electrodes
    • B01J2219/0811—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes employing two or more electrodes employing three electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0822—The electrode being consumed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0824—Details relating to the shape of the electrodes
    • B01J2219/0826—Details relating to the shape of the electrodes essentially linear
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0803—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy
    • B01J2219/0805—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges
    • B01J2219/0807—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electric or magnetic energy giving rise to electric discharges involving electrodes
    • B01J2219/0837—Details relating to the material of the electrodes
    • B01J2219/0839—Carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0871—Heating or cooling of the reactor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0881—Two or more materials
    • B01J2219/0886—Gas-solid
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0894—Processes carried out in the presence of a plasma
    • B01J2219/0898—Hot plasma
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2202/00—Structure or properties of carbon nanotubes
    • C01B2202/02—Single-walled nanotubes
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2202/00—Structure or properties of carbon nanotubes
    • C01B2202/06—Multi-walled nanotubes

Definitions

  • a fullerene is a third form of pure carbon and is different from graphite and diamond, the only two forms known before 1985.
  • a fullerene structure is generally characterized as a two-dimensional carbon array, each carbon atom bonded to three other carbon atoms. The carbon array curves around to meet and j oin with itself as a molecule with cage-like structure and aromatic compound properties.
  • Buckyball contains 60 carbon atoms bonded together in a spherical surface relationship, a structural diagram of which resembles the familiar shape of a soccer ball. Buckyballs often occur in multilayers, that is, a fullerene with multiple concentric spherical surfaces.
  • Single-wall carbon nanotubes (SWNT) are fullerenes of closed-cage carbon molecules typically arranged in cross sectional hexagons and pentagons. Commonly known as “buckytubes,” these cylindrical carbon structures have extraordinary properties, including high electrical and thermal conductivity, as well as high strength and stiffness.
  • Multi-wall carbon nanotubes Concentric, or nested, single-wall carbon cylinders, known as multi-wall carbon nanotubes (MWNT) also occur ⁇ carbon nanotubes having two or more walls have been described.
  • Multi-wall nanotubes possess properties similar to the single- wall carbon nanotubes; however, single-wall carbon nanotubes have fewer defects, rendering them stronger, more conductive, and typically more useful than multi-wall carbon nanotubes.
  • Single-wall carbon nanotubes are believed to be much more free of defects than are multi-wall carbon nanotubes because multi-wall carbon nanotubes can survive occasional defects by forming bridges between the unsaturated carbon of the neighboring cylinders, whereas single-wall carbon nanotubes have no neighboring walls for defect compensation. Multi-wall nanotubes occur more commonly than single wall nanotubes.
  • a further form of fullerene is termed a nanohorn, comprising a single wall fullerene in a conal shape with conical walls at 20° from its longitudinal axis expanding from a smaller end closed by a cap of about 1 nm. diameter to a larger open end of about 2 nm diameter, much like a thimble.
  • nanohorns were found among MWNT produced by laser ablation. They are found in clusters of hundreds or thousands of individual nanohorns apparently held together by van der
  • the clusters appear as nearly homogeneous puffballs, averaging over about 80 nanometers (nm) in diameters, having no preferred or defined growth center, that is, a point from which the nanohorn cluster grows. Characteristically, the nanohorns appear to orient somewhat with their smaller, capped end directed outward. At about 600° K the nanohorn cap closing the smaller end breaks off or opens leaving a frusto-conical single wall carbon nanostructure. Being both single wall carbon nanostructures, nanohorns and SWNT generally share the same properties and advantages, especially the nanohorns without its cap.
  • the nanohorn structure may be more advantageous than the SWNT structure due to its vast surface area; a typical nanohorn surface area in a nanohorn cluster is approximately 250 square meters per gram.
  • a typical nanohorn surface area in a nanohorn cluster is approximately 250 square meters per gram.
  • single-wall carbon nanotubes and nanohorns are a possible strengthening reinforcement in composite materials.
  • the intrinsic electronic properties of single- wall carbon nanotubes and nanohorns also make them electrical conductors and useful in applications involving field emission devices, such as flat-panel displays and in polymers used for radiofrequency interference and electromagnetic shielding that require electrical conductance properties.
  • single- wall carbon nanotubes, ropes of single- wall carbon nanotubes and nanohorns are useful in electrically conductive coatings, polymers, paints, solders, fibers, electrical circuitry, and electronic devices, including batteries, capacitors, transistors, memory elements, current control elements, switches and electrical connectors in micro-devices such as integrated circuits and semiconductor chips used in computers.
  • the single wall nanotubes and nanohorns are also useful as antennas at optical frequencies as constituents of non-linear optical devices and as probes for 2 scanning probe microscopy such as are used in scanning tunneling microscopes (STM) and atomic force microscopes (AFM).
  • the nanotubes and nanqhorns themselves and materials and structures comprising carbon these nanostractures are also useful as supports for t4 catalysts in chemical processes, such as hydrogenation, polymerization and cracking, and in devices such as fuel cells.
  • L6 All known processes for formation of single-wall nanotubes involve a transition- metal catalyst, residues of which are invariably present in the resulting fullerenes.
  • L 8 Likewise, these processes also result in production of varying amounts of carbon material that are not in the form of single-wall nanotubes. In the following, this non- 10 nanotube carbon material is referred to as "amorphous carbon.”
  • One of several methods of synthesizing fullerenes is by DC arc discharge.
  • black body emission is intense.
  • the intense light produced by black body emission in the electric arc method causes a photochemical reaction that diminishes the yields of fullerenes by forming large carbon clusters in the carbon vapor near the electrodes where the vaporized carbon concentration is high and close to the intense light.
  • the fullerenes are exposed to extremely intense UV radiation only briefly, and if carbon rods are heated resistively, only small amounts of UV radiation are produced.
  • larger electrodes that would be used to make fullerenes at high rates by vaporizing more anodic carbon large amounts of UV radiation is produced, which causes the unwanted photochemical reaction of the newly formed fullerenes with the carbon vapors.
  • Nanotubes produced by this method vary in structure, although one structure tends to predominate.
  • the laser vaporization process produces an improved yield of single- wall carbon nanotubes, the product is still heterogeneous, and the nanotubes tend to be too tangled for many potential uses of these materials.
  • the laser vaporization of carbon is a high-energy process, requiring substantial power input for vaporization of graphite.
  • Another way to synthesize carbon nanotubes is by catalytic decomposition of a carbon-containing gas by nanometer-scale metal particles supported on a substrate.
  • the carbon feedstock molecules dissociate on the metal particle surface and the resulting carbon atoms combine to form nanotubes.
  • the method typically produces imperfect multi-walled carbon nanotubes, but under the certain reaction conditions, can produce excellent single- wall carbon nanotubes.
  • One example of this method involves the disproportionation of CO to form single-wall carbon nanotubes and CO 2 catalyzed by transition metal catalyst particles comprising Mo, Fe, Ni, Co, or mixtures thereof residing on a support, such as alumina.
  • the method can use inexpensive feedstocks and moderate temperatures, the yield of single- wall carbon nanotubes is limited due to rapid surrounding of the catalyst particles by a dense tangle of single- wall carbon nanotubes, which acts as a barrier to diffusion of the feedstock gas to the catalyst surface, limiting further nanotube growth. Large amounts of other forms of carbon, such as amorphous carbon and multi-wall carbon nanotubes are also present in the resulting product.
  • All-gas phase processes can be used to form single-wall carbon nanotubes.
  • single-wall carbon nanotubes are synthesized using benzene as the carbon-containing feedstock and ferrocene as a transition metal catalyst precursor.
  • single-wall carbon nanotubes By controlling the partial pressures of benzene and ferrocene and by adding thiophene as a catalyst promoter, single-wall carbon nanotubes can be produced. However, this method also suffers from simultaneous production of multi- wall carbon nanotubes, amorphous carbon, and other products of hydrocarbon pyrolysis under the high temperature conditions necessary to produce high quality single-wall carbon nanotubes.
  • Another method for producing single- wall carbon nanotubes involves an all-gas phase method using high pressure CO as the carbon feedstock and a gaseous transition metal catalyst precursor. This method is effective in making single wall carbon nanotubes without simultaneously making multi-wall nanotubes.
  • the method produces single- wall carbon nanotubes in high purity; less than about 10 wt % of the carbon in the solid product is attributable to other carbon-containing species, including both graphitic and amorphous carbon.
  • the carbon nanotubes from this product are of high quality and purity, there is still a need for a method for producing single- wall carbon nanotubes at higher catalyst productivity and feedstock yields in order to improve the process economics and produce high quality single-wall carbon nanotubes at lower cost.
  • the search for methods to produce single- wall carbon nanotubes and nanohorn clusters at high yield and high catalyst productivity has been an on-going need in order to make nanotubes and nanohorns economically viable in various applications.
  • a primary object of the invention is enhanced production of fullerenes, and more specifically single wall nanotubes. Another object is the enhanced production of clusters of nanohorns. A further object is efficient production of single wall nanotubes. A yet further object is custom production of a preferred diameter and length of single wall nanotubes and nanohorns.
  • the reactor chamber comprises a cooled cathode with a surface presented to an end of at least one anode bar. Each of the cathode and the anode end mutually present a broad areal surface to the other.
  • areal is meant to indicate a functional two-dimensional surface, that is, exploiting the two-dimensional nature of the surface.
  • the typical arc welding rod is 1/8" inch diameter and is functionally employed as a point during operation with its end directed at a welding target, an electrical cathode.
  • the carbon bar of the present invention has an end and typical cross-section of 1 cm by 1 cm for the purpose of establishing a two- dimensional reactor chamber wall and therefore has an areal extent to contain a plasma of atomized carbon together with an opposing cathode wall.
  • the anode end is intentionally small to avoid photochemical reactions caused by anode blackbody emission.
  • the present invention by design ignores the black body emission and exploits the confining nature of the areal surface of the large anode end that enables a pressurized atmosphere of atomized carbon to be maintained between the anode areal surface and the cathode, also with an areal surface opposite the anode end.
  • the cathode and anode are electrically connected to a high amperage power source such that when the anode is brought in near contact with the cathode an electric arc strikes between them over a gap.
  • the anode and cathode have matching surfaces maintained with a constant gap across the surfaces.
  • the gap is very small, resulting in a white-hot anode opposite a cooled cathode.
  • the carbon anode end vaporizes under the electric arc to produce a pressurized reactor chamber.
  • the anode is fed toward the cathode to maintain the preferred gap, which adds to the carbon plasma pressure.
  • gaseous carbon is ejected in high velocity visible jet streams from the reactor chamber open chamber sides. It is suspected that the rate of ejection from the reactor chamber overcomes the photochemical reaction that occurs when the atomized carbon is allowed to dwell around the anode with high blackbody emission.
  • the required carbon plasma pressure is maintained by feeding the anode longitudinally toward the cathode to replenish the plasma at the rate that carbon is expelled from the reactor chamber both in the visible jets and the core deposits (and any other process that exhausts carbon from the reactor chamber, such as in invisible oxides of carbon).
  • the required rate referred to herein (including in the claims below) as the anode feed rate, is that rate that generates and maintains the visible jet streams of atomized carbon.
  • the anode feed rate is a range of rates, all of which include the defining characteristic of generating the visible jets of carbon from the sides of the reactor chamber.
  • an initial anode feed rate the rate at which the visible jet streams are first generated
  • the range of anode feed rate therefore extends between the initial anode feed rate and that rate at which reactor chamber collapses and the anode is driven into physical contact with the cathode. It has been found that a typical feed rate for a carbon bar of 1 cm. by 1 cm. is typically approximately 2.5 cm per minute.
  • the cathode is typically cylindrical rotatable on a cylinder axis to present a change of surface to the anode.
  • the cylinder is a container holding water that circulates into and out of the cylinder.
  • the cathode can also be planar, equivalently presenting a change of surface to the anode by laterally translating the cathode.
  • the anode is mounted on a carriage adjustable in two dimensions useful in maintaining the gap and in aligning the anode end smaller than the cathode with a preferred cathode location.
  • the carriage may also be vertically adjustable to locate the anode along the cathode longitudinally.
  • Gaseous carbon ejected from the reactor chamber from open chamber sides cools in a nonair gas enveloping the reactor chamber and surrounding regions into single wall nanohorn clusters that are collected by a reduced pressure tube (“vacuum”) that collects and sorts nanohorns by size.
  • vacuum reduced pressure tube
  • a portion of the ejected carbon accumulates along the ejection path, forming deposits of fullerenes, refened to as cores, on the cooled cathode that are dislodged when the cathode rotates to a new position.
  • the actual process of obtaining accumulations of fullerenes on the cathode about the reactor chamber is not clearly understood. Therefore, representation of deposits of atomized carbon or generally accumulation is meant to include all other processes for achieving the agglomerate accumulations.
  • the cores are found to comprise 50%
  • the process is scaled with multiple anodes forming multiple reactor chambers with a common cathode.
  • Each anode is mounted to a common carriage that feeds the anodes concurrently toward the cathode in first forming arcs in each reactor chamber and then in maintaining a very hot atmosphere of vaporized carbon in each reactor chamber with an arc gap of only approximately 1-2 mm.
  • vaporized carbon is expelled from the chamber.
  • the temperature in the reactor is uniformly hot such that formations of amorphous carbon within the chamber do not occur.
  • FIG. 1 is a perspective view of the apparatus, including the anode carriage, cathode, and nanohorn collector.
  • FIG. 2 is perspective view of the collector opposite the gas conduit with the anode therebetween presented to the cathode
  • FIG. 3 is a top planar view of a flat end anode presented to a convex curved cathode forming a reactor chamber therebetween.
  • FIG. 4 is a cut-away cross sectional view of the reactor chamber.
  • FIG. 5 is a perspective view of the cylindrical cathode also showing a plurality of anode bars presented orthogonal to the cathode side.
  • FIG. 6a is a perspective view of a planar cathode shown with typical accumulations of fullerene deposits. The figure shows a plurality of anodes aligned vertically with ends presented to the cathode.
  • FIG. 6b is a perspective view of the planar cathode of FIG. 6a, also shown with typical accumulations of fullerene deposits after the anodes have been repositioned at the cathode.
  • FIG. 7 is a cut-away view of the nanohorn collector.
  • FIG. 8 is an artistic representation of a single wall nanotube depicting carbon atoms as balls interconnected hexagonally by electron bonds.
  • FIG. 9 is an artistic representation of a multi-wall nanotube, shown with two concentric single wall tubes.
  • FIG. 10 is an artistic representation of a single wall nanotube of hexagonally interconnected SP2 carbons shown growing from catalysts of metal atoms.
  • FIG. 1 la is an artistic representation of a single nanohorn, shown in side and end views.
  • FIG. 1 lb is an artistic representation of the nanohorn of FIG.
  • FIG. 12a is an artistic representation of a single nanohorn after it has been heated to remove the cap that closes its small end, shown in side and end views
  • FIG. 12b is an artistic representation of the single nanohorn of FIG. 12a, shown in a circular closed end view from front, back and side views.
  • FIG. 13 is a scan of actual nanohorn clusters using a scanning electron microscope. Clusters are seen as three ball-like structures apparently adhering together. The scan is valuable to show the nature of the cluster; individual nanohorns cannot be discerned. Actual nanohorn walls are thin and largely transparent to the image except when the electron scan passes through multiple nanohorn walls.
  • FIG. 14 is a scan of actual nanostructures.
  • the icicle-like elongated growths are believed to be multi-wall nanotubes.
  • DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The fullerene production apparatus 10 of the present invention shown in FIG. 1 comprises a cathode 12, which may or may not be carbon 100, and an anode 14 comprised of carbon spaced apart from the cathode 12 by a small gap 16 of approximately 0.1-2 mm.
  • the cathode 12 and the anode 14 at the gap 16 have opposing matching areal surfaces 12a and 14a with an extent 18 that defines an open- sided broad reactor chamber 20 between the extended anode and cathode opposing surfaces 12a, 14a.
  • the cathode 12 and anode 14 electrically connect to a power source 22, typically 20 to 70 volts at between 30 and 500 amps, such that an electric arc 24 is formed across the gap 16 that vaporizes anodic carbon 102, therein creating a pressurized reactor chamber 20 that exhausts vaporized carbon 102 under pressure in visible jets streams 26 of carbon from reactor chamber sides 28.
  • the reactor chamber 20 remains pressurized and jet streams 26 continue to flow as the anode 14 is fed into the reactor chamber 20 at an anode feed rate.
  • the amperage level and anode feed rate can be varied to produce several different mixes of fullerenes, including single wall nanotubes 30, multi-wall nanotubes 32, and nanohorns 34 and nanohorn clusters 36, shown in FIG. 9-14.
  • a typical range of power is 25 to 30 volts at 90 to 500 amps.
  • Nanohorn production in gaseous reaction chamber exhaust jets 26 is found to maximize with 190 amps with a high feed rate, which yields short multi-wall nanotubes of 5 to 20 nm diameters.
  • the electric arc 24 causes a high reactor chamber temperature, which, together with bombarding electrons from the cathode, continuously consumes the anode 14 and pressurizes the reactor chamber 20 with atomized carbon 102 as the anodic carbon is vaporized.
  • the chamber pressure causes the ejection the atomized carbon
  • the reactor chamber 20 is replenished as additional anodic carbon 102 is vaporized into the reactor chamber maintaining an effective constant pressure.
  • the opposing matching surfaces 12a and 14a forming the reactor chamber 20 typically comprise a concave cathodic surface 12b matching a convex anodic surface 14b.
  • the cathode 12 is cylindrical with a cylinder side 38 presented to the anode 14.
  • the anode 14 typically is an elongate rod 40 with a rectangular cross section of 1-2 cm per side.
  • the anode end 42 presents to the cathode 12.
  • Mismatched anodic and cathodic surfaces evolve into matched surfaces 12a and 14a as the anode 14 is advanced toward the cathode 12 initially in the reactor chamber 20.
  • the actual process involved is not yet clear. It is suspected that anode and cathode matching surfaces 12a, 14a of areal extent 18 are formed from initial mismatched anode and cathode surfaces as fullerenes from vaporized anodic carbon extend the cathode as the expelled carbon grows carbon deposits 44 onto the cathode surface.
  • Gaseous carbon ejected from the reactor chamber is deflected by the deposits as it in turn carves a smooth curved cathode surface in the deposits matching a smooth curved surface on the anode also carved by the stream of ejected gaseous carbon between the close cathode and anode surfaces separated by an equidistant gap throughout the surfaces of only approximately 0.1-2 mm.
  • the arc 24 is struck initially and moves between the anode and cathode surfaces 14a and 12b between closest electrode locations.
  • Anodic carbon 102 is vaporized and deposited on the cooled cathode 12 within the reactor chamber 20, accumulating until the cathode surface with deposits 44 matches the anode surface even as the anode 14 is vaporized.
  • This initial surface step is obviated by commencing the process with a cathodic surface comprising a section presented to the anode 14 with a concave surface 12b and an anode 14 with a convex surface 14b matching the cathodic section concave surface 12b.
  • the anode 14 mounts on a carriage 50 typically with two orthogonal axes of adjustment 52 and 54, a first axis 54 of which is aligned orthogonal to the cathode 12.
  • the carriage 50 may also be vertically adjustable to locate the anode 14 at a preferred position on the cathode 14. Adjustment of the anode 14 on the first axis 54 feeds the anode 14 toward the cathode 12. In operation, the anode 14 is adjusted toward the cathode 12 on the first axis 54 to maintain a preferred gap 16 as the anode 14 is consumed.
  • the preferred gap 16 is that which maintains the anode surface opposite the cathode 12 during operation in white-hot condition, which is approximately 0.1-2 mm. It has been experimentally determined that the atmospheric environment about the reactor 20 influences fullerene production.
  • a selective non-air gas 56 such as nitrogen or argon routed through a gas conduit 58 directed generally at the reactor chamber 20 envelopes the reactor chamber 20 and atomized carbon ejected in jets 26 from the reactor chamber 20, shielding the reactor chamber and the atomized carbon from ambient air and water vapor, which may be detrimental to the fullerene production process.
  • One or more collectors 60 directed at the jet streams 26 collect nanohorns 1036 formed in the jet streams 26 as they cool away from the reactor chamber 20.
  • the collectors 60 are positioned to substantially collect the non-air gas 56 that envelops the jet streams 26, typically opposite the gas conduit 58 so the non-air gas 56 shields the jets 26 of ejected carbon 102 from air, which minimizes formation of oxides of carbon, as it sweeps the formed nanohorns 34 into the collector 60.
  • the collectors 60 comprise a low-pressure tube 62, or "vacuum,” adapted to draw ejected fullerenes into a collector reservoir 64.
  • the collector 60 further comprises a separator 66 that sorts collected nanohorn fullerenes by size.
  • the separator 66 comprises a series of bags 66' of ever smaller filtering mesh.
  • Each bag typically envelops a bag of a smaller mesh down to a first, or finest mesh bag. It has also been experimentally determined that production efficiency and size of single wall nanotubes 30 and nanohorns 34 is enhanced by certain metal catalysts 68, usually a Group VIIIB transition metal such as Mo, Fe, Ni, Co, or mixtures thereof.
  • metal catalysts 68 usually a Group VIIIB transition metal such as Mo, Fe, Ni, Co, or mixtures thereof.
  • one or more metal catalysts 68 are integrated into the carbon anode 14.
  • the catalyst may be homogeneous throughout the anode or it may be filled in a groove longitudinal with the anode (not shown).
  • fullerenes of carbon are discharged from the reactor chamber 20 and grow loosely in deposits 44 attached to the cathodic surface 12. These fullerenes, mostly MWNT, continue to accumulate at the sides of the reactor chamber 20, pushing the accumulation outward as new fullerenes accumulate.
  • the reactor chamber 20 evolves to include a reactor portion 45 extending from the opposing cathodic and anodic surfaces toward and around the anode, spaced therefrom such that vaporized anodic carbon exhausts the reactor between the cathodic deposit and alongside said anode.
  • Fullerene deposits 44, or cores, are harvested by dislodging them from the cathode 12.
  • the anode 14 is withdrawn from the cathode 12 thereby ending the electric arc 24 and defeating the reactor chamber 20.
  • the cathode 12 is then shifted from a first cathode section opposite the anode having deposit accumulations of fullerenes to a second section opposite the anode, moving a prior cathodic surface opposite the anode away from the anode.
  • the cylinder is rotated on its axis 19.
  • it is translated laterally from the anode.
  • the cathode comprises a cylindrical container 70 holding a coolant 71, typically water.
  • a coolant 71 typically water.
  • water or other coolant
  • the cathode container 70 cylindrical or planar, is closed with a lid 72 that prevents escape of water.
  • the anode comprises a plurality of parallel anode bars 14' all connected to the carriage 50 and each opposing a section of a common cathode 12 such that the carriage 50 translates the anode bars 14' together toward the common cathode, each spaced apart therefrom by a respective gap, and each forming a reactor chamber with the cathode.
  • Each is connected to an independent power source 22' such that an electric arc 24 is formed across the respective gaps 18 to each produce fullerenes.
  • the respective gaps 18 are a common separation between respective anodes and the common cathode.

Abstract

L'invention concerne une chambre de réaction à arc électrique, haute température, située entre une anode de carbone consommable et une cathode refroidie produisant du carbone atomisé éjecté à partir de la chambre en flux visible à vitesse gazeuse dans laquelle des nanocornets à paroi unique se forment à mesure que le carbone gazeux refroidit à distance de la chambre. Afin de réaliser une atmosphère de carbone atomisé sous pression dans la chambre de réacteur entre l'anode et la cathode ainsi qu'un arc sur toutes les surfaces superficielles d'électrode entière, l'anode et la cathode présentent des surfaces de couplage entre lesquelles se trouve un espace constant. Par conception, l'espace est très petit résultant en une anode incandescente qui est consommée à une vitesse d'avance d'anode élevée. Un gaz non aérien enveloppe la chambre de réaction et les zones environnantes, ce qui isole la chambre de réaction et les flux de jet de l'air environnant. Le gaz transporte également les nanocornets formés dans un ('vide') réduit qui collecte et trie les nanocornets par taille.
PCT/US2004/006886 2003-12-23 2004-03-04 Appareil a arc electrique destine a fabriquer des fullerenes WO2005068067A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103585942A (zh) * 2013-11-12 2014-02-19 厦门福纳新材料科技有限公司 电弧法富勒烯高效生产装置
WO2015070642A1 (fr) * 2013-11-12 2015-05-21 厦门福纳新材料科技有限公司 Source d'arc à fullerène et appareil d'obtention de fullerène comprenant la source d'arc

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5227038A (en) * 1991-10-04 1993-07-13 William Marsh Rice University Electric arc process for making fullerenes
US5587141A (en) * 1994-02-25 1996-12-24 Director-General Of Industrial Science And Technology Method and device for the production of fullerenes
US20030015414A1 (en) * 2000-04-18 2003-01-23 Hisashi Kajiura Method and system for production fullerene
WO2003064321A1 (fr) * 2002-02-01 2003-08-07 Nanofilm Technologies International Pte Ltd Production de nanotubes

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5227038A (en) * 1991-10-04 1993-07-13 William Marsh Rice University Electric arc process for making fullerenes
US5587141A (en) * 1994-02-25 1996-12-24 Director-General Of Industrial Science And Technology Method and device for the production of fullerenes
US20030015414A1 (en) * 2000-04-18 2003-01-23 Hisashi Kajiura Method and system for production fullerene
WO2003064321A1 (fr) * 2002-02-01 2003-08-07 Nanofilm Technologies International Pte Ltd Production de nanotubes

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103585942A (zh) * 2013-11-12 2014-02-19 厦门福纳新材料科技有限公司 电弧法富勒烯高效生产装置
WO2015070642A1 (fr) * 2013-11-12 2015-05-21 厦门福纳新材料科技有限公司 Source d'arc à fullerène et appareil d'obtention de fullerène comprenant la source d'arc
CN103585942B (zh) * 2013-11-12 2015-12-16 厦门福纳新材料科技有限公司 电弧法富勒烯高效生产装置

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