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The present invention relates generally to the manufacture of carbon nanomaterials. More particularly, the present invention relates to method for fabricating graphitic carbon nanostructures that have a high porosity of particles surface.
Carbon nanostructures, such as fullerenes, carbon nanotubes and carbon onions (multilayer fullerenes), are materials of increasing interest due to their exclusive physical and chemical properties. Graphitic materials can be conductive and create unique nanomaterials such as carbon nanotubes or onion type of carbon nanostructure. The unique properties of graphite can be attributed to highly crystalline or graphitic carbon materials. Usual methods for the synthesis of these materials, such as chemical vapor deposition (CVD), arc-discharge, laser ablation and plasma radiation, are principally limited to high energy assisted conditions at high temperature during the oriented arrangement of stable graphite structures, because of the highly stable graphite structure. Solvothermal synthesis and hot injection are also known to be an applicable method for synthesis of graphitic carbon nanomaterials. Y. Yan et. al. reported the method to synthesis small carbon nanoparticles with uniform diameters of 3-6 nm, carbon onion particles with larger diameters of 30-80 nm, and carbon nanoropes with a length of hundreds of nm and a width of 3-20 nm, by using these methods. Amorphous carbons could transform into various carbon nanostructures because of hydrothermal or solvothermal treatment with a mediocre temperature, which requires strong reductants or expensive carbon sources.
Graphitic nanostructures, such as carbon onions and one-dimensional (1D) graphitic nanostructures have rarely been reported by solution methods since it is difficult to prepare graphite carbon nanostructures in solution-phase because of lack of a suitable force in forming sheet-like crystal structures. The solvothermal synthesis is a simple method to achieve the carbon nanostructures with high yield; while the hot injection method offers a broad synthesis strategy which could be applied into various aromatic molecular polymerization systems in preparing high-quality carbon nanostructures. To obtain the graphitic structure at lower temperature many studies have been carried out on carbonization in the presence of a metal catalyst. The catalyst mostly is a salt of metal such as iron, nickel, or cobalt which is mixed with carbon precursor. Using catalytic graphitization, graphitic materials can be produced at temperatures between 600-1400oC.
A novel synthesis method for fabricating graphitic carbon nanostructures (GCNs) has been presented from sawdust but mixed of several types of nanoparticles by M.Sevilla et. al. This method was established based on the use of catalysts (Fe or Ni) that allows the direct conversion of sawdust into highly graphitized carbon material. The following procedure was used to acquire these graphitic nanoparticles: (a) impregnation of the sawdust particles with iron or nickel salts, (b) carbonization of the impregnated material at a temperature of 900 or 1000 °C, and (c) selective removal of the non-graphitized carbon (amorphous carbon) by an oxidant. The final product is made up of nanosized graphitic carbon structures (i.e., nanocapsules, nanocoils, nanoribbons), which have a good crystallinity.
US Patent (20030099592) describes a method for preparing nanostructures comprise of a primary layered non-cylindrical nanostructure support and at least one type of secondary substantially graphitic nanostructure grown. Both the primary layered nanostructure support and the layered substantially graphitic secondary nanostructure are substantially crystalline, wherein the secondary nanostructure, which will preferably be carbon, has a smaller diameter than the primary non-cylindrical nanostructure.
Another patent (US2008241422 (A1)) presents the method for the aerosol synthesis of carbon nanostructures under atmospheric pressure comprising of a spark generation step of generating a spark between a graphite electrode made of carbon and a metal electrode made of a catalytic metal inducing the graphitization of carbon and vaporizing the carbon component of the graphite electrode. The metal component of the metal electrode utilizes the heat produced by the spark, thereby generating carbon vapor and metal vapour. The carbon nanostructure generation step comprises of cooling and condensing the carbon vapor and the metal vapor to form a graphitic carbon layer and catalytic metal particles. The search of carbon nanostructures involves the graphitic carbon layer on the surface of the catalytic metal particles and covered by the catalytic metal particles.
3) Summary: .
According to the first aspect of the present disclosure, a method for creating graphitic carbon nanospheres (GCNSs) by a CVD method includes: supplying a carbon atom to a catalyser for forming the carbon nanoparticles; and controlling an amount of carbon supply with time and temperature. In this method carbon fibers are used as a supporting substrate for nanometal particles formation. Although there are some researches of producing graphitic carbon nanoparticles (CNPs), but none has studied it in the vertical fixed bed. This research has been carried out to study the formation of graphitic carbon nanoparticles in mass and pure production by using short carbon fiber in fixed bed reactor chemical vapour deposition (FBCVD). The synthesis of graphitic carbon nanoparticles (GCNPs) is done by the catalytic decomposition of acetylene over Fe/CF catalysts in a fixed bed reactor. The catalyst substrate is carbon fiber and metal catalyst with different content of iron are used to deposit on the CF surface. This study indicates that the optimum condition for the growth of GCNP is 600 °C for 1.8% Fe on carbon fiber with 2mm length for an 8 minutes deposition time and 15L/min acetylene flow rate. In this present invention graphitic carbon nanospheres have been produced in large amount of lattice images of various fullerenic carbons and aciniform of nanoparticles which are seldom reported in the literature.
This method includes: forming a catalyzer on a substrate, wherein the GCNS is formed using the catalyzer; arranging the substrate with the catalyzer in a reactor; heating the substrate to a synthesis temperature by pure nitrogen; supplying a raw materials (gases) into the reactor, providing a carbon supply source and reducing agent such as hydrogen; and controlling the concentration and a flow rate of the raw material gas at suitable values for optimization purpose.
4) Description: . .
Carbon nanostructures desire to be formed whilst carbon-containing compounds, such as hydrocarbons and carbon monoxide, interact with hot nanometal surfaces. Recently, it has been acknowledged that an exclusive set of chemical and physical properties can be achieved if one controls the growth and structural characteristics of carbon nanostructures by the use of selected parameters. Unfortunately, conventional methods for producing carbon nanostructures are not suitable for mass production of carbon nanostructures having relatively uniform narrow widths. The width of carbon nanostructures is typically influenced by the size of the catalytic metal particles from which they are grown, which is typically range from about 25 to 450 nm. Better control of, and narrower width nanostructures are highly beneficial for a variety of commercial applications. .
The present invention relates to a process for the mass production of graphitic carbon nanoparticles by decomposition of hydrocarbons on a catalyst in a vertical reactor, wherein the reactor can be operated batch wise or continuously. GCNP here are understood as spherical carbon particles having a diameter of between 35-150 nm, preferably 50 and 80 nm, diameter. These particles are made up of layers of ordered carbon atoms and have a core of different morphology. Because of their dimensions and specific particular properties, the graphitic carbon nanoparticles described are of industrial importance for the production of composite materials. Other possibilities lie in electronic uses, energy uses and medical uses.
The production of carbon nanotubes having diameters of less than 100 nm is also described for hydrocarbons and an Iron based catalyst, on which carbon supports will be decomposed at temperatures between 450-650oC. The known methods include, for example, arc, laser ablation and catalytic methods. In many cases, carbon black amorphous carbon and fibres having large diameters are formed as by-products. In the case of production via catalytic deposition of carbon from hydrocarbons which are gaseous under the reaction conditions acetylene, methane, ethane, ethylene, butane, butene, butadiene, benzene and further carbon-containing educts are mentioned as possible carbon contributor. The catalysts most often comprise of metals, metal oxides or decomposable or reducible metal components. For example, Fe, Mo, Ni, V, Mn, Sn, Co, Cu and others are mentioned as metals in the literature. The formation of carbon nanoparticles and the properties of the formed particles strongly depend on the metal component used as the catalyst or a combination of several metal components, the support material used and the interaction between the catalyst and support. The exhaust gas and its partial pressure, present of hydrogen or other gases, the reaction temperature and the residence time and the reactor used also influence the particle properties. Therefore best quality and high quantity of production is a particular challenge for an industrial process. .
For an industrial production of carbon nanoparticles, e.g. as an ingredient for improving the mechanical properties or conductivity of composite materials, a high space/time yield is to be aimed for, while preserving the particular properties of the nanoparticles and minimizing the energy and operating materials to be used. ..
A GCNPs manufacturing device is shown in FIG. 1A. The device includes a preheater 5, reactor tube 8, heater 7, supply pipe 4, distributor plate 6, first thermocouple 9, second thermocouple 10, first flowmeter 1, second flow meter 2, third flowmeter 3, differential pressure indicator 11, exhausting pipe 12, output flask 13, emission pipe 14, first cylinder 15, second cylinder 16 and third cylinder 17. In the reactor tube 8, a vertically oriented carbon nanoparticle is formed by the CVD method. The inlet gas is heated before reaching the hydrocarbon decomposition temperature by preheater 5. The heater 7 as a ring shaped electric furnace is arranged around the reactor tube 8 so that the heater 4 heats the inside of the reactor tube 8. The first cylinder 15 supplies raw material gas such as acetylene gas as a carbon source. The second cylinder 16 supplies carrier gas such as nitrogen gas. The third cylinder 17 supplies reducing agent gas as hydrogen gas. The supply pipe transports the raw material gas to the bottom of the reactor tube 8. The emission pipe 15 discharges residual gases from the reactor tube 8 after the raw material gases are used for the reaction.
After the processing temperature has been reached, for example 600oC, the nitrogen gas supply is reduced, and simultaneously, the acetylene and hydrogen gas is being supply to the reactor. Specifically, the acetylene gas is supplied at a gas flow rate of 20 lit/min with proportion: 50%, 25% and 25% C2H2/H2/N2. The acetylene gas supply continues for 8 min. During the second operation, 8 min, the acetylene gas supply is reduced from 20 lit/min to 15 lit/min. Acetylene gas is reduced to at least 10 lit/min. The prominent factor in this innovation is the catalyst which is supported on the carbon fibers. The carbon fibers surface are so smooth, therefore there are feeble interaction between the fiber surface and nanometal particles. The nanoparticle of iron oxide separate easily in the gaseous environment and participate in the reaction with carbon atoms.
The object of the present invention is therefore to develop a process for the production of multilayered carbon nanosphere having diameters of between 38 to 150 nm, preferably 50 to 80 nm, by fixed bed reactor which produces the highest possible product yield. The object is achieved in the process according to the invention for the production of graphitic carbon nanoparticles by decomposition of a gaseous hydrocarbon on a catalyst in a vertical bed by avoiding formation of amorphous carbon or other unusable type of nanoparticles.
5) Claims: :
1. A method for manufacturing a graphitic carbon nanosphere by a CVD method comprises of: supplying a carbon atom to a catalyser for formation of the carbon nanoparticles; and controlling the temperature, amount of catalyst and amount of carbon supply with time.
2. The method according to claim 1, wherein controlling the amount of catalyst concentration include: setting the amount of iron salt used in the synthesis.
3. The method according to claim 1, wherein controlling the amount of carbon supply include: setting the amount to be the first amount in the first step of synthesis of the carbon nano particles; and setting the amount to be a second amount in the second step of synthesis, the second amount is smaller than the first amount, and the second step is performed after the first step.
4. A method for manufacturing graphitic carbon nanoparticles by a FBCVD method comprise of: supplying a raw material gas into a vertical reactor in which the raw material gas provides a carbon source; and controlling of a concentration and a flow rate of the raw material gas as illustrated in FIG 1A.
5. The method according to claim 3, further comprises of: controlling a preheater temperature as shown in FIG 1A-5.
6. The method according to claim 3, further comprises of: controlling a synthesis temperature as shown in FIG 1A-9, 10.
7. The method according to claim 4, wherein controlling the concentration and the flow rate includes: setting the concentration to the first concentration or setting the flow rate to the first flow rate in the first step of synthesis of the graphitic carbon nanoparticles (CNPs) as illustrated in FIG 1A-2,3, 4.
8. The method according to claim 5, wherein the first step is defined by time.
9. The method according to claim 2, further comprises of: arranging a substrate in the reactor to form the CNP, wherein a catalyser for growth of the carbon nanoparticles is supported on the substrate.
10. A method for manufacturing a GCNPs by a FBCVD method comprises of: forming a catalyser on a substrate by impregnation method, wherein the carbon nanoparticles is formed using the catalyser; arranging the substrate with the catalyser in a vertical reactor; heating the substrate by inert gas to be a synthesis temperature; supplying a raw material gas into the bottom of the reactor, the raw material gas provides the carbon source; and control the concentration and a flow rate of the raw material gas, wherein the controlling of the concentration and the flow rate includes: setting the concentration to the first concentration or setting the flow rate to a first flow rate at a first step of synthesis of the graphitic carbon nanoparticles; and setting the concentration to the second concentration or setting the flow rate in the second flow rate at the second step of synthesis of GCNPs, the second concentration is smaller than the first concentration, and the second flow rate is smaller than the first flow rate, and the second step is performed after the first step.
11. The method according to claim 10, wherein the first step is an initial step of beginning the synthesis based on a predetermined time, controlling the concentration and the flow rate further includes switching the inert gas to the process gas when the temperature reach to synthesis temperature.
12. The method according to claim 11, further comprises of: supplying a carrier gas into the reactor, wherein the raw material gas is acetylene gas and the second concentration is smaller than the first concentration and the second flow rate is smaller than the first flow rate.
13. The method according to claim 10, further comprises of: measuring a metal concentration on a surface of the substrate, wherein the first step is an initial step from the beginning of synthesis to a predetermined time.
14. A method according in claim 4, exhibits the aciniform of an extraordinary porous materials, graphitic layers, lattice surface of particles and FIG.1B, 2B, 3B, 4B.
A low cost method of producing graphitic carbon nanosphere (GCNS) in large quantities and low temperature is revealed. The present invention illustrates the improved the synthesis of carbon nanostructure by a fixed bed CVD procedure. From the typical concentrations of gaseous species in the stainless steel vertical reactor, hydrocarbon circumstance including C2H2 and nanoparticle of iron oxide can be the precursors for the formation of GCNS in the CVD chamber.
8)Brief description of drawing
FIGURE 1A: Sketch of a typical fix-bed reactor setup. A cylindrical reactor is affixed within a high-temperature furnace with appropriate temperature, pressure, and gas flow controls, connected to a data logging system.
FIGURE 1B: Low magnificent image of production
FIGURE 2B: Aciniform image of carbon nanoparticle
FIGURE 3B: Graphitic layers of each particle detect in this image.
FIGURE 4B: This image show the rough and porous surface of carbon nanoparticle which is suitable to settle other nanoparticle.
Bahagian C / Part C:
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Pangkalan data /Databases
Kata kunci Carian / Keyword search
United States Patent and Trademark Office (USPTO)
1.Graphitic carbon nanostructures
2.Onion type of carbon nanoparticles
European Patent Office (EPO)
1.Graphitic carbon nanostructures
2.Onion type of carbon nanoparticles
Intellectual Property Office of Singapore
1.Graphitic carbon nanostructures
2.Onion type of carbon nanoparticles
The Industrial Property Digital Library (IPDL, JPO) http://www19.ipdl.inpit.go.jp/PA1/cgi-bin/PA1INIT?1175476102765
1.Graphitic carbon nanostructures
2.Onion type of carbon nanoparticles
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WRITING PATENT SPECIFICATION
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Field of Invention
The field of invention is a general broad statement describing the art or technology to which the invention relates.
The background describes the known prior art, the disadvantages / needs that are being overcome / met by the disclosed invention.
The background frequently identifies prior patents, US and foreign. Key features of the invention compared with the prior art are described and explained.
This section should present the general idea of the claimed invention in summarized form. The summary may point out the advantages of the invention and how it solves previously existing problems, preferably those problems identified in the background of the invention.
The description starts off with general background information and progresses to more detailed information about the invention (could be product or process and its parts).
The description must be written as complete and thorough as any new information to the patent application cannot be added once it is filed. Changes can only be made to the subject matter that could be reasonably inferred from the original drawings or description.
Each claim should be a single sentence, and where a claim sets forth a number of elements or steps, each element or step of the claims should be separated by a line indentation.
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The abstract is a short summary of your invention and how it can be used. The abstract should consist the following;
Description of the invention and what it is used for;
Description of the main components and how they work;
Fairly short, not more than 150 words.
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PRIOR ART SEARCH
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Prior art may include;
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2.0 Why to Search for Prior Art?
Prior art search will help you to:
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write your patent application
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The results of a good patent search should reveal any identical, similar, or partially similar inventions to the one you might patent.
3.0 Where to Search for Prior Art?
1. United States Patent and Trademark Office (The USPTO)
Covers issued and published U.S. patents from 1790
2. European Patent Office
Contains patents from all over the world
3. Intellectual Property Office of Singapore
4. Patent Cooperation Treaty Application (PCT)
Contains published PCT applications dating back to 1978
4.0 How to Search for Prior Art?
An on-line prior art search can be done by a keyword search
List the keywords that you would use to describe the invention
Think of all possible aspects of the invention and choose keyword that describe each aspect
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