Nanotechnology – Eun-Hwa Hong, Kun-Hong Lee, Chang-Mo Ryu, Jong-Hoon Han, Jae-eun Yoo, IIJIN NANOTECH Co Ltd, POHANG UNIVERSITY OF SECIENCE AND TECHNOLOGYY FOUNDATION, Iljin Nanotech Co Ltd, Pohang University of Science and Technology Foundation POSTECH
Abstract for “Method and apparatus for synthesizing carbon nanotubes”
“A method for synthesizing carbon-nanotubes is provided, as well as a carbon nanotube synthesizing device. The reactor is heated using a variety of heating methods, including microwave irradiation and electromagnetic inductive heating, radiofrequency heating, laser heating, or radio frequency heating. A catalyst is then introduced to the reactor. The reactor is fed with carbon source gas, hydrogen sulfide, carbon source and hydrogen sulfide gases, or carbon source and hydrogen gas, or inert and carbon gas. This allows for the production of carbon nanotubes using the locally heated catalyst.
Background for “Method and apparatus for synthesizing carbon nanotubes”
“1. “1.
“The invention concerns the synthesizing of carbon nanotubes and, more specifically, to a method for synthesizing these nanotubes using local heating. The apparatus is used to accomplish this.”
“2. “2.
It is well-known that a carbon nanotube can be microscopically formed so that one carbon element is combined and three neighboring carbon elements. A hexagonal ring is formed when the carbon atoms combine, and a plan composed of repeated hexagonal rings, like a honeycomb, is rolled to form a cylindrical shape. The carbon nanotube’s diameter is usually several angstroms to several tens or thousands of nanometers. Its length is several tens to several thousands of times greater than its diameter. This carbon nanotube is well-known for its metal property as well as semiconductive property. It also has excellent physical and electric properties. The carbon nanotube’s conductivity and/or Semiconductivity have been widely used in a wide range of fields.
Conventionally, carbon nanotubes can be synthesized using a variety of methods, including an arc discharge method (or laser evaporation), a thermal chemical vapour deposition (CVD), or a catalytic synthesizing process. These processes are done at temperatures ranging from several hundred to several thousand degrees Celsius or in a vacuum to remove the high temperature conditions.
“Moreover, these conventional methods heat an entire reactor to reach a reaction temperature for the production of carbon nanotubes. All substances, such as catalysts and reactant gases, that are added to the reactor are heated. When a catalyst is loaded onto a support or substrate, it should be made of heat-resistant material that can tolerate high reactions temperatures as described above. This means that the choice of a substrate or support for loading a catalyst should be limited.
“To address the above problems, the invention provides a method for synthesizing carbon-nanotubes. This allows a support or substrate to load a catalyst that is not heated at high temperatures by heating it locally.
“It is a second aspect of the present invention that provides a carbon nanotube synthesizing device used for performing this method.”
To achieve the first feature, the invention provides a method for synthesizing carbon-nanotubes. The method involves the introduction of a catalyst into a reactor. A reactant gas containing carbon source gases is then supplied over the catalyst. Carbon nanotubes are then grown from the heated catalyst.
“The local heating can be achieved using radio frequency heating, electromagnetic inductive heating or laser heating.
“To realize the second feature, the invention provides an apparatus for synthesizing nanotubes. This apparatus comprises a reactor to receive a catalyst, a reactant gases supplier for supplying reactant gases containing carbon source gas into a reactor, and a local heat for heating the catalyst in the reactor.
“The apparatus could also include a supplier of catalyst gas for the supply of catalyst into the reactor’s gas phase.”
“The local heater could include a microwave generator to generate microwaves and a microwave guide that connects to the reactor. The microwave guide guides the microwaves to reach the reactor. A high-frequency coil may be installed around the reactor. It also might include a power supply to apply high-frequency currents to the high frequency coil. A radio frequency generator may be installed near the reactor. A local heater might include a laser beam source installed near the reactor and a lens to focus the laser beams generated from the laser beam generator.
“According the present invention, carbon Nanotubes can be synthesized at lower temperatures, that is, when the whole reactor is kept at a low temperature by local heating. A substrate or support for loading a catalyst can be made of glass or polymer material.
“The following description will detail an embodiment of the invention with reference to the attached illustrations. The scope and spirit of the present invention are not limited to the above-described embodiments. Many variations are possible. To help anyone with knowledge of the art, the embodiments of the present invention are provided. The drawings show members in exaggerated shapes. The same reference numbers denote the same members.
Referring to FIG. “Referring to FIG. 1. A method for synthesizing carbon-nanotubes according an embodiment of this invention can be done using a carbon-nanotube synthesizing device as shown in FIG. 6. FIG. 6. is proposed as a way to realize the concept of local heating suggested by the embodiments of the present invention.
“Referring FIGS. The carbon nanotube synthesizing apparatus shown in FIGS. 2, 3, and 6 is described in FIGS. 6. A reactor 100 is used to receive a boat 150 that loads with catalyst powder 135 or a substrate 135, which loads with catalyst 135. Is the catalytic powder 135 made? The catalyst 135 in FIG. is loaded into the catalytic powder 135 to make it. 2 is formed, for instance, of a transition metal on support 130. You can also make the reactor 100 as a quartz tube.
The reactor 100 has a local heater 200 to supply microwaves with heat to the catalyst powder 135?. This is substantially the catalyst 135. A local heater 200 could include a microwave generator 250 to generate microwaves, and a guide 210 to guide the microwaves towards the reactor 100.
A reactant gas supplier 300 is installed for supplying a reactant gaz used to synthesize carbon nanotubes. A discharger 600 is also installed for discharging a reaction gas. Gas bombes may be used to supply a carbon source gas, such as hydrogen sulfide or hydrocarbon (H2S), or to supply hydrogen gas (H2), or an inert gaz which can be supplied with the carbon source and mass flow controllers. On/off valves 350 are also installed to the ducts connecting the reactant gas supplier 300 and the reactor 100. These allow for the control of a gas flow rate. There may be multiple sets of the MFC 310, the bombe and the on/off 350.
“The catalyst 135 can be supplied with a loading of a precursor or transition metal on the substrate 130 or support 130, as shown in FIGS. It can be supplied in gas phase if required. For example, to supply a catalyst in gas phase with a precursor to a metal like iron (Fe), nickel, or cobalt, for example, ferrocene (10H10) or iron pentacarbonyl (5Fe(CO),5) must be vaporized.
A catalytic gas supplier 400 can be added to reactor 100 to meet this requirement. Catalytic gas supplier 400 contains a saturator (410) for vaporizing solid or liquid catalysts or precursors, a water bathtub 430 to accommodate the saturator (410), and a circulator (450) for controlling water temperature in the water baths 430 and circulating water. The reactor 100 is fed a gaseous catalyst by the saturator (410) via a conduit. This catalyst acts in the reactor 100.
“Here, the four-port 370 is located at the intersection of the conduits connected to the reactant gases supplier 300 and catalytic gas suppliers 400. It can be used to induce the flow of a liquid. A temperature controller 500 can be used to maintain the catalyst in gasphase when supplying it with catalyst. The temperature controller 500 has a sliding unit and a temperature reading unit. The temperature controller 500 measures and displays the internal temperature of reactor 100 with a thermocouple or similar device. It then reads the result and maintains that temperature so that a catalyst is able to be injected into reactor 100 in gas phase.
“A method for synthesizing carbon nanotubes with such a carbon-nanotube synthesizing device as described above will also be described using the flowchart in FIG. 1. Step 1100: A catalyst 135 from FIG. In step 1100, a catalyst 135 of FIG. 2 or 3 is added to reactor 100 as shown in FIG. 6. The catalyst 135 can be made by loading a precursor or transition metal onto the powder type support 130. 2 or on the substrate 131, as shown in FIG. 3. What is the catalyst powder 135? The catalyst powder 135 may be manufactured by loading it on the powder support 130. It can then be placed on the boat 150 or the like, and introduced into the reactor 100. Alternately, the reactor 100 may be used to introduce the substrate 131 if the catalyst 135 has been loaded onto the substrate 131.
“For catalyst 135, a transitional metal such as iron or nickel or a compound consisting of the transitional metal, such as cobalt, nickel, or cobalt, or a metal sulfide like cobalt sulfide. Iron sulfide. Nickel sulfide. Metal sulfide. An organic compound, such as cobalt naphtenate, that contains the transition metal can also be used as catalyst 135
“The catalyst 135 can be made by loading the precursor to a transition metal containing iron or nickel on the support 130 in FIG. 2. Using an impregnation, incipient moisture or an ion exchange method. The catalyst powder 135 can be made from the 135-manufactured catalyst. The catalyst 135 may also be used after it has been reduced, calcinated, sulfided or carbonized to give it a variety of properties.
“The substrate 130 or support 130 may be made of silicon oxide (SiO2), or aluminum oxide (Al2O3) that is not heated by microwaves. You can also use the carbon (C) powder support 130 which can be heated using microwaves and other similar methods. You can place the catalyst 135 on the support 130 on the boat 150 in FIG. 6. The catalyst 135 may be placed on the support 130 using deposition or painting. The catalyst 135 can also be applied to substrate 131 by spraying, painting, or deposition. The catalyst 135 can be used immediately after loading or after it has been reduced and calcinated or sulfiding, carbonized.
Below are examples of how to load the catalyst 135 onto the support 130.
“TEST EXAMPLE 1”.
“The catalyst 135 is loaded on the support 130, or the substrate 133. It is then placed on the boat 150 and inserted in the reactor 100. The reactor 100 is then filled with heat-resistant material like quartz wool 190 to prevent heat transmission from the outside to the inside. The next step is 1200 in FIG. 1. A reactant gas is then supplied to the reactor 100. Preferably, the reactant gas contains a carbon source gaz.
“In step 1300 the catalyst 135 can be locally heated by irradiating microwaves on the reactor 100 accommodating catalyst 135 or catalyst powder 135?” The catalyst 135 is made of a material that can be dielectrically heated using microwaves. As such, microwaves are used to heat the catalyst 135 as shown in FIG. 2. You can generate microwaves with either 2.45 GHz or 800 W power.
“This heating can be restricted to the catalyst 135 so that the reactant gases, the substrate 131, support 130 and boat 150 not supplied into reactor 100 are not heated. The support 130, boat 150, and substrate 131 can be made of glass or other polymer materials such as plastic.
“As shown at FIGS. 3. and 4. Carbon nanotubes 170 are made from the catalyst 135 using the reaction of a reactant gas containing carbon source gases that has been locally heated. This is step 1300 in FIG. 1. As the carbon source gas, you can use hydrocarbon gas like methane gas (acetylene gas), propane gas, or benzene. Alternately, you can use a reactant gas where hydrocarbon gas is mixed in with hydrogen gas. An inert gas may also be used as a carrier.
“Results of synthesizing carbon-nanotubes using catalyst powder 135 FIG. 7 shows the scan electron microscope (SEM), image of Fe (5 wt.%)/C. 7.”
“As mentioned above, in case of catalyst powder 135? Both the catalyst 135 or the support 130 can both be heated at the same time. The catalyst 135 cannot be heated if it is loaded on the substrate 130 or substrate 135, which are made of silicon oxide (SiO2), or glass, that is not heated with microwaves. Hydrocarbon gas and hydrogen sulfide gas can be combined to create carbon nanotubes.
“TEST EXAMPLE 2”.
Instead of using iron, cobalt, or nickel as a catalyst for the production of carbon nanotubes, a compound that contains the transition metal can be used to act as a catalyst. It can also be heated locally by microwaves. SiO2 can be used to form support 130. It is not heated by microwaves and can also be used to make carbon nanotubes.
“TEST EXAMPLE #3”
“Meanwhile also, in the case where plastic is used to form support 130, carbon nanotubes are possible by microwave heating.”
“TEST EXAMPLE”
Carbon nanotubes can also be made if a glass substrate is used instead of a plastic one.
“TEST EXAMPLE”
“A glass substrate is coated with cobalt naphthalate and dried. This allows the catalyst cobalt naphtenate to be loaded on the substrate. The catalyst is the glass substrate that has been loaded with cobalt naphtenate. Next, the reactor is filled with C2H2S and H2S at a flow rate 10 ml/min. The reactor is then purged by removing the reactor. The glass substrate is then irradiated with microwaves for nine minutes. The glass substrate is not heated in this step. Instead, only the catalyst is heated locally and selectively to synthesize carbon nanotubes. FIG. FIG. 11 shows an SEM image of the synthesized carbon-nanotubes. Alternately, C2H2S and H2S can be diluted with water and flowed into the reactor at a flow of 10 ml/min.3 ml/min.117 ml/min. Microwaves are used to irradiate the substrate for 5 mins to trigger the reaction of H2 gas with the C2H2, C2S and H2 gases so that carbon nanotubes may be synthesized. FIG. FIG. 12 shows a SEM image of carbon nanotubes synthesized in this manner.”
“In a method for synthesizing carbon nanotubes, according to the embodiments of the present invention, a catalyst may be supplied into reactor 100 in a gas phase and not in a powder form. A catalyst precursor, such as iron pentacarbonyl or ferrocene, is vaporized using the saturator (410) of FIG. 6, or similar, and then supplied to the reactor 100.
“In this instance, the catalyst precursors or catalysts that are supplied into reactor 100 are heated using a local heating method such as a microwave heating method. The catalysts can float in reactor 100. The reactor 100 can produce carbon nanotubes from floating catalysts. This is possible by reacting hydrocarbon or other similar substances. Carbon nanotubes can also be made in gas phase by using catalysts as described above. This allows for mass production of carbon nanotubes.
“FIG. “FIG. FIG. 6 shows a carbon nanotube synthesizing device. 6. is used to irradiate microwaves in order to achieve the local heating described by the embodiments of the invention. An electromagnetic inductive heating technique can be used to heat the local area. FIG. 13 shows a carbon nanotube-synthesizing apparatus with a local heater 200. It is possible to propose a high frequency coil 215 around reactor 100. The high-frequency wire 215 can then be connected to a high frequency power supply 255. The high-frequency coil 215 is energized by high-frequency current. This creates an electromagnetic field around high-frequency coil 215. The reactor 100 can heat the catalyst 135 by a change of the electromagnetic field.
“FIG. “FIG. A laser heating method can be used to heat the local area, as illustrated in FIG. 14. A laser beam generator 710, for example, is located near reactor 100. The laser beams 750 produced by the laser beam generator 710 focus on a lens 725 that is held by a 727 lens holder to enable the present invention’s local heating. The catalyst 135 or catalyst powder 135 can be used in this instance. The reactor 100 can be controlled to heat the catalyst 135 or the catalyst powder 135 by controlling the focus of the laser beams.
“FIG. “FIG. A radio frequency heating method can be used to heat the local area, as illustrated in FIG. 15. A RF generator 800, for example, is located near reactor 100. The RF generator 800 can generate RF to heat the embodiments of the invention. The RF can be used to heat the catalyst 135 in the gas phase or catalyst powder 135 can be heated selectively.”
The present invention improves on a traditional method for synthesizing carbon-nanotubes at high temperatures by heating the entire reactor. The present invention allows carbon nanotubes to be made even if the entire reactor is kept at a lower temperature. A local heating method can be used to heat a catalyst, even if the reactor temperature is kept low. A substrate or support made of glass, or polymer materials such as plastic, that cannot be used at high temperatures can be used.
“Although this invention has been described in relation to a specific embodiment, it will be obvious to someone of ordinary skill that modifications to the described embodiment can be made without departing form the spirit and scope.
Summary for “Method and apparatus for synthesizing carbon nanotubes”
“1. “1.
“The invention concerns the synthesizing of carbon nanotubes and, more specifically, to a method for synthesizing these nanotubes using local heating. The apparatus is used to accomplish this.”
“2. “2.
It is well-known that a carbon nanotube can be microscopically formed so that one carbon element is combined and three neighboring carbon elements. A hexagonal ring is formed when the carbon atoms combine, and a plan composed of repeated hexagonal rings, like a honeycomb, is rolled to form a cylindrical shape. The carbon nanotube’s diameter is usually several angstroms to several tens or thousands of nanometers. Its length is several tens to several thousands of times greater than its diameter. This carbon nanotube is well-known for its metal property as well as semiconductive property. It also has excellent physical and electric properties. The carbon nanotube’s conductivity and/or Semiconductivity have been widely used in a wide range of fields.
Conventionally, carbon nanotubes can be synthesized using a variety of methods, including an arc discharge method (or laser evaporation), a thermal chemical vapour deposition (CVD), or a catalytic synthesizing process. These processes are done at temperatures ranging from several hundred to several thousand degrees Celsius or in a vacuum to remove the high temperature conditions.
“Moreover, these conventional methods heat an entire reactor to reach a reaction temperature for the production of carbon nanotubes. All substances, such as catalysts and reactant gases, that are added to the reactor are heated. When a catalyst is loaded onto a support or substrate, it should be made of heat-resistant material that can tolerate high reactions temperatures as described above. This means that the choice of a substrate or support for loading a catalyst should be limited.
“To address the above problems, the invention provides a method for synthesizing carbon-nanotubes. This allows a support or substrate to load a catalyst that is not heated at high temperatures by heating it locally.
“It is a second aspect of the present invention that provides a carbon nanotube synthesizing device used for performing this method.”
To achieve the first feature, the invention provides a method for synthesizing carbon-nanotubes. The method involves the introduction of a catalyst into a reactor. A reactant gas containing carbon source gases is then supplied over the catalyst. Carbon nanotubes are then grown from the heated catalyst.
“The local heating can be achieved using radio frequency heating, electromagnetic inductive heating or laser heating.
“To realize the second feature, the invention provides an apparatus for synthesizing nanotubes. This apparatus comprises a reactor to receive a catalyst, a reactant gases supplier for supplying reactant gases containing carbon source gas into a reactor, and a local heat for heating the catalyst in the reactor.
“The apparatus could also include a supplier of catalyst gas for the supply of catalyst into the reactor’s gas phase.”
“The local heater could include a microwave generator to generate microwaves and a microwave guide that connects to the reactor. The microwave guide guides the microwaves to reach the reactor. A high-frequency coil may be installed around the reactor. It also might include a power supply to apply high-frequency currents to the high frequency coil. A radio frequency generator may be installed near the reactor. A local heater might include a laser beam source installed near the reactor and a lens to focus the laser beams generated from the laser beam generator.
“According the present invention, carbon Nanotubes can be synthesized at lower temperatures, that is, when the whole reactor is kept at a low temperature by local heating. A substrate or support for loading a catalyst can be made of glass or polymer material.
“The following description will detail an embodiment of the invention with reference to the attached illustrations. The scope and spirit of the present invention are not limited to the above-described embodiments. Many variations are possible. To help anyone with knowledge of the art, the embodiments of the present invention are provided. The drawings show members in exaggerated shapes. The same reference numbers denote the same members.
Referring to FIG. “Referring to FIG. 1. A method for synthesizing carbon-nanotubes according an embodiment of this invention can be done using a carbon-nanotube synthesizing device as shown in FIG. 6. FIG. 6. is proposed as a way to realize the concept of local heating suggested by the embodiments of the present invention.
“Referring FIGS. The carbon nanotube synthesizing apparatus shown in FIGS. 2, 3, and 6 is described in FIGS. 6. A reactor 100 is used to receive a boat 150 that loads with catalyst powder 135 or a substrate 135, which loads with catalyst 135. Is the catalytic powder 135 made? The catalyst 135 in FIG. is loaded into the catalytic powder 135 to make it. 2 is formed, for instance, of a transition metal on support 130. You can also make the reactor 100 as a quartz tube.
The reactor 100 has a local heater 200 to supply microwaves with heat to the catalyst powder 135?. This is substantially the catalyst 135. A local heater 200 could include a microwave generator 250 to generate microwaves, and a guide 210 to guide the microwaves towards the reactor 100.
A reactant gas supplier 300 is installed for supplying a reactant gaz used to synthesize carbon nanotubes. A discharger 600 is also installed for discharging a reaction gas. Gas bombes may be used to supply a carbon source gas, such as hydrogen sulfide or hydrocarbon (H2S), or to supply hydrogen gas (H2), or an inert gaz which can be supplied with the carbon source and mass flow controllers. On/off valves 350 are also installed to the ducts connecting the reactant gas supplier 300 and the reactor 100. These allow for the control of a gas flow rate. There may be multiple sets of the MFC 310, the bombe and the on/off 350.
“The catalyst 135 can be supplied with a loading of a precursor or transition metal on the substrate 130 or support 130, as shown in FIGS. It can be supplied in gas phase if required. For example, to supply a catalyst in gas phase with a precursor to a metal like iron (Fe), nickel, or cobalt, for example, ferrocene (10H10) or iron pentacarbonyl (5Fe(CO),5) must be vaporized.
A catalytic gas supplier 400 can be added to reactor 100 to meet this requirement. Catalytic gas supplier 400 contains a saturator (410) for vaporizing solid or liquid catalysts or precursors, a water bathtub 430 to accommodate the saturator (410), and a circulator (450) for controlling water temperature in the water baths 430 and circulating water. The reactor 100 is fed a gaseous catalyst by the saturator (410) via a conduit. This catalyst acts in the reactor 100.
“Here, the four-port 370 is located at the intersection of the conduits connected to the reactant gases supplier 300 and catalytic gas suppliers 400. It can be used to induce the flow of a liquid. A temperature controller 500 can be used to maintain the catalyst in gasphase when supplying it with catalyst. The temperature controller 500 has a sliding unit and a temperature reading unit. The temperature controller 500 measures and displays the internal temperature of reactor 100 with a thermocouple or similar device. It then reads the result and maintains that temperature so that a catalyst is able to be injected into reactor 100 in gas phase.
“A method for synthesizing carbon nanotubes with such a carbon-nanotube synthesizing device as described above will also be described using the flowchart in FIG. 1. Step 1100: A catalyst 135 from FIG. In step 1100, a catalyst 135 of FIG. 2 or 3 is added to reactor 100 as shown in FIG. 6. The catalyst 135 can be made by loading a precursor or transition metal onto the powder type support 130. 2 or on the substrate 131, as shown in FIG. 3. What is the catalyst powder 135? The catalyst powder 135 may be manufactured by loading it on the powder support 130. It can then be placed on the boat 150 or the like, and introduced into the reactor 100. Alternately, the reactor 100 may be used to introduce the substrate 131 if the catalyst 135 has been loaded onto the substrate 131.
“For catalyst 135, a transitional metal such as iron or nickel or a compound consisting of the transitional metal, such as cobalt, nickel, or cobalt, or a metal sulfide like cobalt sulfide. Iron sulfide. Nickel sulfide. Metal sulfide. An organic compound, such as cobalt naphtenate, that contains the transition metal can also be used as catalyst 135
“The catalyst 135 can be made by loading the precursor to a transition metal containing iron or nickel on the support 130 in FIG. 2. Using an impregnation, incipient moisture or an ion exchange method. The catalyst powder 135 can be made from the 135-manufactured catalyst. The catalyst 135 may also be used after it has been reduced, calcinated, sulfided or carbonized to give it a variety of properties.
“The substrate 130 or support 130 may be made of silicon oxide (SiO2), or aluminum oxide (Al2O3) that is not heated by microwaves. You can also use the carbon (C) powder support 130 which can be heated using microwaves and other similar methods. You can place the catalyst 135 on the support 130 on the boat 150 in FIG. 6. The catalyst 135 may be placed on the support 130 using deposition or painting. The catalyst 135 can also be applied to substrate 131 by spraying, painting, or deposition. The catalyst 135 can be used immediately after loading or after it has been reduced and calcinated or sulfiding, carbonized.
Below are examples of how to load the catalyst 135 onto the support 130.
“TEST EXAMPLE 1”.
“The catalyst 135 is loaded on the support 130, or the substrate 133. It is then placed on the boat 150 and inserted in the reactor 100. The reactor 100 is then filled with heat-resistant material like quartz wool 190 to prevent heat transmission from the outside to the inside. The next step is 1200 in FIG. 1. A reactant gas is then supplied to the reactor 100. Preferably, the reactant gas contains a carbon source gaz.
“In step 1300 the catalyst 135 can be locally heated by irradiating microwaves on the reactor 100 accommodating catalyst 135 or catalyst powder 135?” The catalyst 135 is made of a material that can be dielectrically heated using microwaves. As such, microwaves are used to heat the catalyst 135 as shown in FIG. 2. You can generate microwaves with either 2.45 GHz or 800 W power.
“This heating can be restricted to the catalyst 135 so that the reactant gases, the substrate 131, support 130 and boat 150 not supplied into reactor 100 are not heated. The support 130, boat 150, and substrate 131 can be made of glass or other polymer materials such as plastic.
“As shown at FIGS. 3. and 4. Carbon nanotubes 170 are made from the catalyst 135 using the reaction of a reactant gas containing carbon source gases that has been locally heated. This is step 1300 in FIG. 1. As the carbon source gas, you can use hydrocarbon gas like methane gas (acetylene gas), propane gas, or benzene. Alternately, you can use a reactant gas where hydrocarbon gas is mixed in with hydrogen gas. An inert gas may also be used as a carrier.
“Results of synthesizing carbon-nanotubes using catalyst powder 135 FIG. 7 shows the scan electron microscope (SEM), image of Fe (5 wt.%)/C. 7.”
“As mentioned above, in case of catalyst powder 135? Both the catalyst 135 or the support 130 can both be heated at the same time. The catalyst 135 cannot be heated if it is loaded on the substrate 130 or substrate 135, which are made of silicon oxide (SiO2), or glass, that is not heated with microwaves. Hydrocarbon gas and hydrogen sulfide gas can be combined to create carbon nanotubes.
“TEST EXAMPLE 2”.
Instead of using iron, cobalt, or nickel as a catalyst for the production of carbon nanotubes, a compound that contains the transition metal can be used to act as a catalyst. It can also be heated locally by microwaves. SiO2 can be used to form support 130. It is not heated by microwaves and can also be used to make carbon nanotubes.
“TEST EXAMPLE #3”
“Meanwhile also, in the case where plastic is used to form support 130, carbon nanotubes are possible by microwave heating.”
“TEST EXAMPLE”
Carbon nanotubes can also be made if a glass substrate is used instead of a plastic one.
“TEST EXAMPLE”
“A glass substrate is coated with cobalt naphthalate and dried. This allows the catalyst cobalt naphtenate to be loaded on the substrate. The catalyst is the glass substrate that has been loaded with cobalt naphtenate. Next, the reactor is filled with C2H2S and H2S at a flow rate 10 ml/min. The reactor is then purged by removing the reactor. The glass substrate is then irradiated with microwaves for nine minutes. The glass substrate is not heated in this step. Instead, only the catalyst is heated locally and selectively to synthesize carbon nanotubes. FIG. FIG. 11 shows an SEM image of the synthesized carbon-nanotubes. Alternately, C2H2S and H2S can be diluted with water and flowed into the reactor at a flow of 10 ml/min.3 ml/min.117 ml/min. Microwaves are used to irradiate the substrate for 5 mins to trigger the reaction of H2 gas with the C2H2, C2S and H2 gases so that carbon nanotubes may be synthesized. FIG. FIG. 12 shows a SEM image of carbon nanotubes synthesized in this manner.”
“In a method for synthesizing carbon nanotubes, according to the embodiments of the present invention, a catalyst may be supplied into reactor 100 in a gas phase and not in a powder form. A catalyst precursor, such as iron pentacarbonyl or ferrocene, is vaporized using the saturator (410) of FIG. 6, or similar, and then supplied to the reactor 100.
“In this instance, the catalyst precursors or catalysts that are supplied into reactor 100 are heated using a local heating method such as a microwave heating method. The catalysts can float in reactor 100. The reactor 100 can produce carbon nanotubes from floating catalysts. This is possible by reacting hydrocarbon or other similar substances. Carbon nanotubes can also be made in gas phase by using catalysts as described above. This allows for mass production of carbon nanotubes.
“FIG. “FIG. FIG. 6 shows a carbon nanotube synthesizing device. 6. is used to irradiate microwaves in order to achieve the local heating described by the embodiments of the invention. An electromagnetic inductive heating technique can be used to heat the local area. FIG. 13 shows a carbon nanotube-synthesizing apparatus with a local heater 200. It is possible to propose a high frequency coil 215 around reactor 100. The high-frequency wire 215 can then be connected to a high frequency power supply 255. The high-frequency coil 215 is energized by high-frequency current. This creates an electromagnetic field around high-frequency coil 215. The reactor 100 can heat the catalyst 135 by a change of the electromagnetic field.
“FIG. “FIG. A laser heating method can be used to heat the local area, as illustrated in FIG. 14. A laser beam generator 710, for example, is located near reactor 100. The laser beams 750 produced by the laser beam generator 710 focus on a lens 725 that is held by a 727 lens holder to enable the present invention’s local heating. The catalyst 135 or catalyst powder 135 can be used in this instance. The reactor 100 can be controlled to heat the catalyst 135 or the catalyst powder 135 by controlling the focus of the laser beams.
“FIG. “FIG. A radio frequency heating method can be used to heat the local area, as illustrated in FIG. 15. A RF generator 800, for example, is located near reactor 100. The RF generator 800 can generate RF to heat the embodiments of the invention. The RF can be used to heat the catalyst 135 in the gas phase or catalyst powder 135 can be heated selectively.”
The present invention improves on a traditional method for synthesizing carbon-nanotubes at high temperatures by heating the entire reactor. The present invention allows carbon nanotubes to be made even if the entire reactor is kept at a lower temperature. A local heating method can be used to heat a catalyst, even if the reactor temperature is kept low. A substrate or support made of glass, or polymer materials such as plastic, that cannot be used at high temperatures can be used.
“Although this invention has been described in relation to a specific embodiment, it will be obvious to someone of ordinary skill that modifications to the described embodiment can be made without departing form the spirit and scope.
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