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WO2025049036A1 - Procédé de fabrication de nanotubes de carbone assisté par plasma - Google Patents

Procédé de fabrication de nanotubes de carbone assisté par plasma Download PDF

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Publication number
WO2025049036A1
WO2025049036A1 PCT/US2024/040571 US2024040571W WO2025049036A1 WO 2025049036 A1 WO2025049036 A1 WO 2025049036A1 US 2024040571 W US2024040571 W US 2024040571W WO 2025049036 A1 WO2025049036 A1 WO 2025049036A1
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Prior art keywords
plasma
metal
carbon
catalyst
vol
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Inventor
Robert J. Colby
Robert A. Johnson
Sophie LIU
Ning Ma
Steven Pyl
Sumathy RAMAN
Emre TÜRKÖZ
Kun Wang
Jonathan Mitchell
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ExxonMobil Technology and Engineering Co
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ExxonMobil Technology and Engineering Co
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    • 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
    • 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
    • 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
    • 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
    • B01J2219/0892—Materials to be treated involving catalytically active material

Definitions

  • This application relates to systems and methods for production of carbon nano-scale structures, such as carbon nanotubes or carbon nanofibers.
  • FC-CVD Floating catalyst chemical vapor deposition
  • a typical FC-CVD process includes introducing a feed comprising a precatalyst and a carbon source into a tubular reactor at relatively high temperature of -1,000 °C or greater.
  • the pre-catalyst is transformed into active catalyst, and the carbon source is decomposed to generate a reactive carbon intermediate which is further reacted with the catalyst to form carbon nanotubes.
  • Pre-catalysts are usually organometallic iron sources such as ferrocene.
  • the iron (or other metal) from the catalyst precursors tends to deposit on the walls of the reactor. This can result in loss of 50 mol % or more of the metal from the pre-catalyst. Additionally, after this metal deposition begins, coke formation is also observed on the walls of conventional reactors. Deposition occurs because when the pre-catalyst is decomposed at a temperature typically between 700° C. and 1000° C, the resulting metal has a higher phase stability as an atom deposited on a surface, as opposed to remaining in the gas phase. As a result, when a pre-catalyst is heated through the temperature range 700° C.-1000 0 C, deposition of metal on exposed surfaces can occur.
  • Disclosed herein is an example method for forming carbon nanotubes comprising: volatilizing a metal in a plasma to form an active catalyst; flowing the active catalyst and a carbon source into a floating catalyst chemical vapor deposition reactor; and pyrolyzing at least a portion of the carbon source on the active catalyst in a pyrolysis zone of the floating catalyst chemical vapor deposition reactor to form carbon nanotubes on the active catalyst.
  • a reaction system for forming carbon nanotubes comprising: a floating catalyst chemical vapor deposition reactor comprising a pyrolysis zone; and a plasma configured to generate a volatilized metal from a metal source; wherein the plasma and the floating catalyst chemical vapor deposition reactor are directly fluidically coupled, wherein the floating catalyst chemical vapor deposition reactor is configured to coalesce the volatilized metal to form active catalyst, wherein the floating catalyst chemical vapor deposition reactor is configured to pyrolyze a carbon source to produce pyrolyzed carbon on the active catalyst, and wherein the floating catalyst chemical vapor deposition reactor is configured to form carbon nanotubes on the active catalyst from the pyrolyzed carbon on the active catalyst.
  • FIG. 1 is an illustrative depiction of an FC-CVD process in accordance with certain embodiments of the present disclosure.
  • FIG. 2 is a scanning electron microscope micrograph of carbon nanotubes produced in accordance with certain embodiments of the present disclosure.
  • FIG. 3 is a scanning electron microscope micrograph of carbon nanotubes produced in accordance with certain embodiments of the present disclosure.
  • FIG. 4 is a scanning electron microscope micrograph of carbon nanotubes produced in accordance with certain embodiments of the present disclosure.
  • FIG. 5 is a scanning electron microscope micrograph of carbon nanotubes produced in accordance with certain embodiments of the present disclosure.
  • Carbon fibers, nanofibers, and nanotubes are allotropes of carbon that have a cylindrical nanostructure.
  • Carbon nanofibers and nanotubes are members of the fullerene structural family, which includes the spherical carbon balls termed “fullerene.’'
  • the walls of the carbon nanotubes are formed from sheets of carbon in a graphene structure.
  • nanotubes include single wall nanotubes and multiple wall nanotubes of any length.
  • FC-CVD floating catalyst chemical vapor deposition
  • Conventional FC-CVD processes for producing caron nanotubes include forming an active catalyst in-situ within an FC-CVD reactor by thermal decomposition of a pre-catalyst to form the active catalyst.
  • Commonly used pre-catalysts include compounds containing iron, cobalt, and/or nickel containing with some specific examples including Fe(CO)s and organometallic compounds such as ferrocene. The metal in the pre-catalyst is converted to the active metal catalyst.
  • FC-CVD floating catalyst chemical vapor deposition
  • the methods disclosed herein utilize plasma to directly volatilize a metal to form an active catalyst which can be fed directly into an FC-CVD reactor without additional quenching.
  • the presently disclosed methods for producing carbon nanotubes in FC-CVD have several advantages over conventional methods of producing carbon nanotubes including that the active catalyst can be directly produced from cheaper sources of metal such as the elemental metallic form of the metal.
  • the disclosed methods have higher utilization of elemental metal as compared to conventional FC-CVD processes thereby requiring less catalyst per unit of carbon nanotube produced.
  • the active catalyst produced by the methods disclosed herein allows for increased rate of carbon nanotube production by reducing reactor residence time and facilitating reactor scale-up with more efficient use of reactor volume.
  • the active catalyst produced by the methods disclosed herein also has less tendency to deposit on reactor walls. Additionally, the plasma volatilization step allows for fine control of catalyst morphology and particle size, thus giving additional process control variables to affect the physical properties of the carbon nanotubes produced and to control coke formation.
  • Another advantage of the presently disclosed systems and methods for production of carbon nanotubes includes that the hydrocarbon source and active catalyst can be well mixed before introduction into the FC-CVD reactor. It is desirable to have a well-mixed flow- of activated catalyst and hydrocarbon into the FC-CVD reactor such that the formation of carbon nanotubes is increased.
  • FC-CVD reactors require a mixing means which induce turbulence into the hydrocarbon source and pre-catalyst to thoroughly mix the hydrocarbon source and precatalyst prior to the pre-catalyst decomposing to the active catalyst.
  • efficient formation of carbon nanotubes at the product end of the reactor is facilitated by having a substantially laminar flow with little or no mixing.
  • conventional FC-CVD reactors the initial mixing of reactants can be achieved in a variety of manners, so that the flow is well-mixed even though the amount of turbulence in the flow is reduced or minimized.
  • reactants can be well-mixed in a small-scale reactor while maintaining a Reynolds number below 1 ,000, or even below 500.
  • creating a well-mixed flow- at the beginning of the reactor will result in a turbulent gas flow with a Reynolds number greater than 5,000.
  • a means for reducing the Reynolds number of the flow to roughly 500 or less, and preferably to about 10 is required as the flow reaches the product end of the reactor.
  • the systems and methods for production of carbon nano-scale structures disclosed herein allow for thorough mixing of the hydrocarbon source and active catalyst and does not require additional rector components to reduce the Reynolds number to below 5,000.
  • the plasma generated active catalyst allows for turbulent flow production of carbon nano-scale structures where the flow through the FC-CVD reactor has a Reynolds number greater than 5,000.
  • the flow through the FC-CVD reactor has a Reynolds number in a range of 5,000 to 20,000.
  • the flow through the FC-CVD reactor has a Reynolds number in a range of 5,000 to 8,000, 5,000 to 10,000, 5,000 to 15,000, or 5,000 to 20,000.
  • Turbulent flow production of carbon nano-scale structures may have several advantages as compared to conventional FC-CVD processes, including, that the active catalyst and carbon source are well mixed within the FC-CVD reactor, heat transfer in turbulent flow is much greater than laminar flow, and carbon nano-structures with relatively lower levels of entanglement can be produced.
  • a reactor system for carbon nanotube formation performs at least three types of reactions.
  • One reaction is plasma volatilization of a metal (M) with heat generated from plasma to form an active catalyst (M*) as shown in Reaction 1.
  • a second reaction is pyrolysis of a carbon source such as methane to provide H2 and pyrolyzed carbon (C*) for forming the carbon nanotubes as shown in Reaction 2.
  • a carbon source such as methane
  • C* pyrolyzed carbon
  • C* + M* - > Carbon Nanotubes [0025]
  • a portion of the pyrolyzed carbon (C*) forms amorphous carbon and/or graphitic carbon in addition to the carbon nanotubes.
  • the volatilization of metal in Reaction 1 can be carried out by any suitable plasma.
  • the plasma can be generated by any suitable type of plasma generator including, but not limited to DC plasma generators, RF plasma generators, microwave plasma generators, inductively coupled plasma generators, arc plasma generators, or a combination thereof.
  • the plasma generator produces plasma by a variety of means. For example, plasma is produced by arc discharge between two electrodes and metal is fed into the resulting plasma. Alternatively, or in addition, the metal can compose the electrodes themselves to be ablated off to produce volatilized metal. Alternatively, or in addition, metal is fed into a plasma torch sustained by a microwave plasma generator.
  • the temperature of the plasma ranges from 4,000 K - 7,000 K or any suitable temperature to volatilize the metal. Alternatively, from 4,000 K -5,000 K, 5,000 K - 6,000 K, 6,000 K - 7,000 K, or any ranges therebetween.
  • the metal includes iron, cobalt, manganese, tungsten, molybdenum, and combinations thereof.
  • the metal is introduced into the plasma by any suitable means.
  • the metal is introduced into the plasma in a liquid or solid form.
  • the metal is in a powder form, granular form, as an electrode within a plasma, as a solid piece such as a bar or wire, or combinations thereof.
  • the metal is introduced into the plasma in a liquid form such as a molten metal form or dissolved into a carrier fluid as a metal solution.
  • the plasma volatilization of the metal forms the active catalyst (M*) as a nanoparticle catalyst in an aerosol state.
  • the FC-CVD reactor is directly fluidly coupled to the plasma and the FC-CVD reactor is operated at a temperature cool enough to coalesce the volatilized metal to form nanoparticles of the active catalyst (M*).
  • the active catalyst (M*) has a particle size in a range of 1 nm to 100 nm. Alternatively, in a range of 1 nm to 75 nm, 1 nm to 50 nm, 1 nm to 25 nm, 1 nm to 10 nm, or any ranges therebetween.
  • the plasma volatilization of the metal forms an aerosol with a metal concentration suitable for forming carbon nanotubes such as a concentration of metal in a range of 1,000 pg/m 3 to 100,000 pg/m 3 .
  • a metal concentration suitable for forming carbon nanotubes such as a concentration of metal in a range of 1,000 pg/m 3 to 100,000 pg/m 3 .
  • a carrier gas is utilized with the plasma to carry the active catalyst (M*) particles.
  • Carrier gases include, without limitation, noble gasses such as argon, as well as nitrogen, helium and/or hydrogen, for example.
  • the carbon source for producing the pyrolyzed carbon (C*) for production of nanotubes includes Cl -CIO hydrocarbon alkanes, alkenes, alkynes, aromatics, and/or naphthenes. Some specific examples of carbon sources include methane, ethane, ethylene, acetylene, propane, propylene, butane, butadiene, benzene, and combinations thereof.
  • the carbon sources include hydrocarbons from refinery' streams such as an ethane steam cracker effluent and/or fluidized catalytic cracker (FCC) off gas.
  • the carbon source includes C1-C10 alcohols.
  • the pyrolysis of the carbon source in Reaction 2 can be carried out by any suitable methods.
  • the carbon source may be introduced into an FC-CVD reactor operated at a temperature suitable to pyrolyze at least a portion of the carbon source.
  • the carbon source is contacted with a plasma to pyrolyze the carbon source.
  • the carbon source is used as the carrier gas in the plasma thereby generating the pyrolyzed carbon as well as active catalyst (M*).
  • the carbon source is introduced into a separate plasma from the plasma which produces the active catalyst (M*).
  • the temperature in the pyrolysis environment can be up to 1000° C. or more, or up to 1100° C. or more, or up to 1200° C. or more, such as up to 1600° C. or possibly still higher.
  • the carbon source can be pre-heated before introduction into a pyrolysis zone such as in the FC-CVD reactor.
  • a feed to an FC-CVD reactor includes an active catalyst (M*) and a carbon source.
  • a feed to an FC-CVD reactor includes an active catalyst (M*) and a pyrolyzed carbon source (C*).
  • a feed to an FC-CVD reactor includes a carrier gas.
  • a feed to an FC-CVD reactor includes hydrogen co-feed and/or a carrier gas. When present, the hydrogen co-feed can be introduced into the FC- CVD reactor in an amount of 500 mole % to 5000 mole % of the carbon source or pyrolyzed carbon source (C*) introduced into the FC-CVD reactor.
  • the hydrogen co-feed can be introduced into the FC-CVD reactor in an amount of 500 mole % to 1000 mole %, 1000 mole % to 2000 mole %, 2000 mole % to 5000 mole %, or any ranges therebetween.
  • the carrier gas can be introduced into the FC-CVD reactor in an amount of 1500 mole % to 10,000 mole % of the carbon source or pyrolyzed carbon source (C*) introduced into the FC-CVD reactor.
  • the carrier gas can be introduced into the FC-CVD reactor in an amount of 1500 mole % to 3000 mole %, 3000 mole % to 5000 mole %, 5000 mole % to 10,000 mole %, or any ranges therebetween.
  • the hydrogen containing gas can also include CO so that the hydrogen containing gas corresponds to a synthesis gas.
  • Synthesis gas can also optionally contain water and / or CO2.
  • using a hydrogen co-feed can provide an additional advantage for further reducing or minimizing carbon deposition within the reactor. Under pyrolysis conditions, both carbon atoms and hydrogen are formed. Carbon atoms can tend to be deposited on the surfaces of the reactor.
  • having a hydrogen co-feed can reduce or minimize the tendency for the carbon atoms to deposit on a surface and / or can facilitate removing carbon atoms that might deposit on a surface.
  • an increased amount of carbon can remain in the gas phase in some form until the gas flow reaches the cooler temperatures in the zone for formation of carbon nanotubes.
  • a feed to an FC-CVD reactor includes a sulfur source such as elemental sulfur and/or thiophene in an amount of 0.001 mol % to 5.0 mol % of the amount of methane or other carbon source introduced into the reactor.
  • a sulfur source such as elemental sulfur and/or thiophene in an amount of 0.001 mol % to 5.0 mol % of the amount of methane or other carbon source introduced into the reactor.
  • a feed to an FC-CVD reactor includes a carbon source in an amount of 1 vol.% to 10 vol.% of the feed.
  • a feed to an FC-CVD reactor includes a carbon source in an amount of from 1 vol.% to 3 vol.%, from 3 vol.% to 6 vol.%, or from 6 vol.% to 10 vol.%., or any ranges therebetween.
  • a feed to an FC-CVD reactor includes a hydrogen co-feed in an amount of 20 vol.% to 50 vol.%.
  • a feed to an FC-CVD reactor includes a hydrogen co-feed in an amount from 20 vol.% to 30 vol.%, from 30 vol.% to 40 vol.%, from 40 vol.% to 50 vol.%. or any other ranges therebetween.
  • a feed to an FC-CVD reactor includes a carrier gas in an amount of 50 vol.% to 80 vol.%.
  • a feed to an FC-CVD reactor includes a carrier gas in an amount of 50 vol.% to 60 vol.%, 60 vol.% to 70 vol.%, 70 vol.% to 80 vol.%, or any ranges therebetween.
  • the carbon source can be supplemented with a hydrocarbon that forms free radicals under the pyrolysis conditions.
  • a hydrocarbon that forms free radicals under the pyrolysis conditions.
  • free radicals By forming free radicals, the temperature needed for methane pyrolysis can be reduced.
  • One option can be to introduce propane and /or butane with a methane feed. Propane and butane are often available as part of a “condensate”’ stream at natural gas production sites.
  • Another option can be to use a free radical precursor that provides free radicals that have a longer lifetime.
  • Toluene is an example of a hydrocarbon that can provide stabilized free radicals within the pyrolysis environment. When additional hydrocarbons are used to provide free radicals in the pyrolysis environment, the amount of additional hydrocarbons can correspond to 0.
  • One or more of the components of the feed to the FC-CVD reactor can be heated prior to introduction into the FC-CVD reactor.
  • One option for heating the gas flow can be to use multiple heating stages.
  • an initial heating stage can correspond to a furnace used for heating reactors, such as the type of furnace used in a steam cracking reaction system.
  • Conventional furnaces can be used to heat one or more of the components of the FC-CVD feed to a temperature of 1000 °C or higher. Additional heating to further increase the temperature to 1100 °C or more, or 1200 °C or more, can be provided by a variety of methods.
  • One option can be to use electric heating to heat the walls of the conduit containing the gas flow.
  • the conduit for heating the gas flow prior to entering the reactor can be sized appropriately to allow for efficient heat transfer.
  • Other options can include induction heating or plasma heating. Because pyrolysis is an endo thermic process, the temperature of the gas flow can decrease as the pyrolysis reaction proceeds. Thus, it can be desirable to heat the gas flow to a temperature above 1000 °C., so that a sufficient volume within the reactor will be above 1000 °C as the endothermic pyrolysis process cools the flow. Some additional pyrolysis can still occur after the flow cools to below 1000 °C. but the reaction rate is slower. Still another option can be to include electric heating elements within the gas flow.
  • the carbon source for pyrolysis and / or the pyrolyzed carbon source (C*) and/or active catalyst (M*) can be mixed prior to introduction into the FC-CVD reactor and/or be mixed in the reactor by introducing the feed components into the FC-CVD.
  • at least one of the carbon sources for pyrolysis and the active catalyst (M*) can be mixed with the heated gas flow prior to entering the reactor.
  • a portion of the heated gas flow and /or a portion of the hydrocarbons for pyrolysis can be introduced into the reactor at a downstream location in the reactor relative to the direction of flow. Introducing different portions of the gas flow at different locations within the reactor can assist with managing the reaction profile in the reactor.
  • the amount of methane available for pyrolysis in the early parts of the reactor can be reduced or minimized, to further reduce the likelihood of early carbon nanotube formation and / or early deposition of carbon on the surfaces of the reactor.
  • the FC-CVD reactor is operated at a temperature in a range of 800 °C to 1600 °C. Alternatively, from 800 °C to 1000 °C, 1000 °C to 1200 °C, 1200 °C to 1600 °C, or any ranges therebetween. In embodiments, the FC-CVD reactor is operated at a pressure in a range of 50 kPa to 200 kPa. In embodiments, the FC-CVD reactor is operated at atmospheric pressure (101.325 kPa). Alternatively, at a pressure in a range of 50 kPa to 100 kPa, 100 kPa to 150 kPa, 150 kPa to 200 kPa, or any ranges therebetween.
  • the velocity of the gas within the reactor can be relatively high.
  • the velocity within the reactor can determine the residence time of the reactants within the pyrolysis zone.
  • a high velocity in combination with a low concentration of hydrocarbons in the total flow and a temperature greater than 1000 °C a high level of conversion can be achieved while having a low residence time.
  • Having a low residence time in the pyrolysis zone of the reactor can reduce or minimize carbon deposition on surfaces in the reactor prior to the products reaching the zone for carbon nanotube formation.
  • the average residence time for the reactor can range from 0.05 seconds to 5.0 seconds, or 0.05 seconds to 1.0 seconds, or 0. 1 seconds to 5.0 seconds, or any ranges therebetween.
  • the FC-CVD reactor includes a horizontal FC-CVD reactor and/or a vertical FC-CVD reactor.
  • the FC-CVD reactor can include any suitable configuration including, but not limited to, a flat-flame reactor the reactants are introduced into the plasma, a co-flow reactor where the reactants are introduced into the plasma from the top and bottom creating a coflowing flame, a counter-flow reactor where the reactants are introduced into the plasma from opposite directions, and/or a slot burner configuration where the plasma emits from a slot which the reactants are introduced.
  • FIG. 1 is an illustrative depiction of an FC-CVD process 100 in accordance with certain embodiments of the present disclosure. While only elements necessary to understand the principal operation of FC-CVD process 100 are shown in FIG. 1, one of ordinary skill in the art will readily appreciate that additional elements and/or steps can be integrated into FIG. 1 without detracting from the disclosed embodiments.
  • FC-CVD process 100 begins with introducing carrier gas stream 102 into plasma 104. In plasma 104 a metal pre-catalyst is volatilized by plasma to form a metal aerosol.
  • the metal pre-catalyst can be of any form such as a powder form, granular form, as an electrode within the plasma, as a solid piece such as a bar or wire or introduced as a metal solution in aqueous carrier.
  • the carrier gas combines with the metal aerosol to form activated catalyst stream 138.
  • activated catalyst stream 138 is combined with recycle stream 122 and feed stream 134 to form reactor feed stream 112.
  • Hydrocarbon stream 124 contains the carbon source for producing carbon nanotubes.
  • hydrocarbon stream 124 is preheated in heat exchanger 126.
  • a portion of the hydrocarbon stream can be split into stream 128 and introduced into FC-CVD reactor 106.
  • FC-CVD reactor 106 the components introduced into FC-CVD reactor are reacted to from carbon nanotubes.
  • the carbon nanotubes can be removed from FC-CVD reactor 106 via stream 130 to collection unit 110.
  • Collection unit 110 may include a spool type collection unit or any other type of collection suitable for collecting carbon nanotubes to produce product nano tube stream 132.
  • a reactor effluent stream 114 is withdrawn from FC-CVD reactor 106 which may include unreacted components of feeds to FC- CVD reactor 106 which is introduced into separation unit 108.
  • Separation unit 108 includes equipment to separate the components of the reactor effluent stream 114 into recycle stream 118 and waste stream 116.
  • Recycle stream 118 may include the components of the reactor effluent stream 114 such as hydrogen, carrier gas, unreacted hydrocarbon, and other components useful to react to form further carbon nanotube product.
  • Recycle stream 1 18 may be heated in heat exchanger 120 and may optionally be split into recycle stream 122 for combining with activated catalyst stream 138 and recycle stream 136 for introduction into FC-CVD reactor 106.
  • the present disclosure may provide systems and methods for production of carbon nano-scale structures, such as carbon nanotubes or carbon nanofiber, and, more particularly, disclosed are systems and methods for production of carbon nano-scale structures using plasma generated active catalyst.
  • the methods and systems may include any of the various features disclosed herein, including one or more of the following Embodiments.
  • Embodiment 1 A method for forming carbon nanotubes comprising: volatilizing a metal in a plasma to form an active catalyst; flowing the active catalyst and a carbon source into a floating catalyst chemical vapor deposition reactor; and pyrolyzing at least a portion of the carbon source on the active catalyst in a pyrolysis zone of the floating catalyst chemical vapor deposition reactor to form carbon nanotubes on the active catalyst.
  • Embodiment 2 The method of embodiment 1 wherein the active catalyst and the carbon source turbulently flow through the floating catalyst chemical vapor deposition reactor.
  • Embodiment 3 The method of any of embodiments 1-2 wherein a Reynolds number of the active catalyst and the carbon source flowing through the floating catalyst chemical vapor deposition reactor is in a range of about 5,000 to about 20,000.
  • Embodiment 4 The method of any of embodiments 1-3 wherein the active catalyst is introduced into the floating catalyst chemical vapor deposition reactor without quenching.
  • Embodiment 5 The method of any of embodiments 1-4 wherein the metal comprises at least one metal selected from the group consisting of iron, cobalt, manganese, nickel, tungsten, molybdenum, and combinations thereof.
  • Embodiment 6 The method of any of embodiments 1-5 wherein the plasma is generated by at least one generator selected from the group consisting of a DC plasma generator, an RF plasma generator, a microwave plasma generator, an inductively coupled plasma generator, an arc plasma generators, and combinations thereof.
  • Embodiment 7. The method of any of embodiments 1-6 wherein the metal is introduced into the plasma as a powder, as granular form, as an electrode within the plasma, as a bar, as a wire, or a combination thereof.
  • Embodiment 8 The method of any of embodiments 1-7 wherein the metal is introduced into the plasma in a molten metal form and/or dissolved into a carrier fluid as a metal solution.
  • Embodiment 9 The method of any of embodiments 1-8 further comprising introducing a carrier gas into the plasma and wherein a feed to the floating catalyst chemical vapor deposition reactor includes the activated metal catalyst suspended in the carrier gas.
  • Embodiment 10 The method of embodiment 9 wherein the carrier gas comprises at least one gas selected from the group consisting of a noble gas, hydrogen helium, and combinations thereof.
  • Embodiment 11 The method of any of embodiments 1-10 wherein a feed to the floating catalyst chemical vapor deposition reactor comprises a carbon source in an amount of about 1 vol.% to about 10 vol.% of the feed, a hydrogen co-feed in an amount of about 20 vol.% to about 50 vol.%., and a carrier gas in an amount of about 50 vol.% to about 80 vol.%.
  • Embodiment 12 The method of any of embodiments 1-11 wherein the carbon source comprises a Cl -CIO hydrocarbon.
  • Embodiment 13 The method of any of embodiments 1-12 wherein the carbon source comprises a Cl -CIO alcohol.
  • Embodiment 14 The method of any of embodiments 1-13 wherein the carbon source comprises ethane steam cracker effluent and/or fluidized catalytic cracker off gas.
  • Embodiment 15 A reaction system for forming carbon nanotubes comprising: a floating catalyst chemical vapor deposition reactor comprising a pyrolysis zone; and a plasma configured to generate a volatilized metal from a metal source; wherein the plasma and the floating catalyst chemical vapor deposition reactor are directly fluidically coupled, wherein the floating catalyst chemical vapor deposition reactor is configured to coalesce the volatilized metal to form active catalyst, wherein the floating catalyst chemical vapor deposition reactor is configured to pyrolyze a carbon source to produce pyrolyzed carbon on the active catalyst, and wherein the floating catalyst chemical vapor deposition reactor is configured to form carbon nanotubes on the active catalyst from the pyrolyzed carbon on the active catalyst.
  • Embodiment 16 The reaction system of embodiment 15 wherein the metal source comprises iron electrodes and wherein the plasma comprises arc plasma.
  • Embodiment 17 The reaction system of any of embodiments 15-16 wherein the source is generated by at least one source selected from the group consisting of a DC plasma generator. an RF plasma generator, a micro wave plasma generator, an inductively coupled plasma generator, an arc plasma generator, and combinations thereof.
  • a DC plasma generator an RF plasma generator, a micro wave plasma generator, an inductively coupled plasma generator, an arc plasma generator, and combinations thereof.
  • Embodiment 18 The reaction system of any of embodiments 15-17 wherein the metal source in a powder form, a granular form, as an electrode within the plasma, as a bar, as a wire, or a combination thereof.
  • Embodiment 19 The reaction system of any of embodiments 15-18 wherein the metal source comprises at least one metal selected from the group consisting of iron, cobalt, manganese, nickel, tungsten, molybdenum, and combinations thereof.
  • Embodiment 20 The reaction system of any of embodiments 15-19 further comprising a feed to the floating catalyst chemical vapor deposition reactor, wherein the feed comprises the carbon source in an amount of about 1 vol.% to about 10 vol.% of the feed, a hydrogen co-feed in an amount of about 20 vol.% to about 50 vol.%., and a carrier gas in an amount of about 50 vol.% to about 80 vol.%.
  • Embodiment 21 The reaction system of any of embodiments 15-20 wherein the carbon source comprises a Cl -CIO hydrocarbon.
  • Embodiment 22 The reaction system of any of embodiments 15-21 wherein the carbon source comprises a Cl -CIO alcohol.
  • Embodiment 23 The reaction system of any of embodiments 15-22 wherein the carbon source comprises ethane steam cracker effluent and/or fluidized catalytic cracker off gas.
  • Embodiment 24 The reaction system of any of embodiments 15-23 wherein the carbon source comprises synthesis gas.
  • carbon nanotubes were synthesized using ethylene feed with iron nanoparticle catalyst generated by plasma.
  • the experiment was performed in a down-flow quartz reactor at 900 °C and ambient pressure.
  • the catalyst feed w as generated by flowing the nitrogen through a particle generator which generates iron nanoparticle catalyst via spark ablation of iron electrodes.
  • the particle generator was operated at 1.3 kV voltage and 10 mA current for the duration of the experiment.
  • the flux of nanoparticles generated was measured before and after the reaction using a differential mobility analyzer and the flux was observed to be steady at about 10 4 p.g/m 3 .
  • the notional residence time in the reactor was about 1.4 sec at the reaction temperature.
  • the reaction was carried out for a period of 2 hours and the gaseous products from the reactor effluent were continuously analyzed by a gas chromatography thermal conductivity detector (GC-TCD) to measure methane, ethane, and acetylene. Thereafter, the feeds were stopped, and the reactor allowed to cool down under flowing nitrogen. The carbon product deposited on the reactor tube was recovered for SEM analysis.
  • FIG. 2 and FIG. 3 are SEM images of the recovered carbon product. It was observed that single wall and multi-wall carbon nanotubes were produced.
  • carbon nanotubes were synthesized using iron nanoparticles generated by plasma with an ethane/helium co-feed.
  • the experiment was performed in a down-flow quartz reactor at 900 °C and ambient pressure.
  • the feed to the reactor was 12 standard cubic centimeters (seem) ethylene of 95% ethane / 5% helium, 131.4 seem hydrogen, and a catalyst feed including 300 seem of N2 containing iron nanoparticles.
  • the catalyst feed was generated by flowing the nitrogen through a particle generator which generates iron nanoparticle catalyst via spark ablation of iron electrodes.
  • the particle generator was operated at 1.3 kV voltage and 10 mA current for the duration of the experiment.
  • the flux of nanoparticles generated was measured before and after the reaction using a differential mobility analyzer and the flux was observed to be steady at about 10 4 p.g/m 3 .
  • the notional residence time in the reactor was about 1 .4 sec at the reaction temperature.
  • the reaction was carried out for a period of 2 hours and the gaseous products from the reactor effluent were continuously analyzed by a gas chromatography thermal conductivity detector (GC-TCD) to measure methane, ethane, and acetylene. Thereafter, the feeds were stopped, and the reactor allowed to cool down under flowing nitrogen.
  • the carbon product deposited on the reactor tube was recovered for SEM analysis.
  • FIG. 4 and FIG. 5 are SEM images of the recovered carbon product. It was observed that single wall and multi-wall carbon nanotubes were produced.
  • compositions, methods, and processes are described herein in terms of “comprising,” “containing,” “having,” or “including” various components or steps, the compositions and methods can also "consist essentially of’ or ‘‘consist of the various components and steps.
  • the phrases, unless otherwise specified, “consists essentially of and “consisting essentially of’ do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the disclosure, additionally, they do not exclude impurities and variances normally associated with the elements and materials used.

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Abstract

L'invention concerne un procédé de formation de nanotubes de carbone qui peut comprendre : la volatilisation d'un métal à l'état de plasma pour former un catalyseur actif ; l'écoulement du catalyseur actif et d'une source de carbone dans un réacteur de dépôt chimique en phase vapeur de catalyseur flottant ; et la pyrolyse d'au moins une partie de la source de carbone sur le catalyseur actif dans une zone de pyrolyse du réacteur de dépôt chimique en phase vapeur de catalyseur flottant pour former des nanotubes de carbone sur le catalyseur actif.
PCT/US2024/040571 2023-08-31 2024-08-01 Procédé de fabrication de nanotubes de carbone assisté par plasma Pending WO2025049036A1 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN120270982A (zh) * 2025-04-08 2025-07-08 江西中科景合新能源科技股份有限公司 一种均匀控温的碳纳米管生产方法

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Publication number Priority date Publication date Assignee Title
US8137653B1 (en) * 2011-01-30 2012-03-20 Mcd Technologies S.A R.L. System and method for producing carbon nanotubes
US20220185670A1 (en) * 2020-12-16 2022-06-16 Exxonmobil Research And Engineering Company Reactor for carbon nanotube and nanofiber production
CA3232446A1 (fr) * 2021-10-19 2023-04-27 Lg Chem, Ltd. Appareil de synthese de nanotubes de carbone
CA3232423A1 (fr) * 2021-10-19 2023-04-27 Lg Chem, Ltd. Procede de synthese de nanotubes de carbone

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8137653B1 (en) * 2011-01-30 2012-03-20 Mcd Technologies S.A R.L. System and method for producing carbon nanotubes
US20220185670A1 (en) * 2020-12-16 2022-06-16 Exxonmobil Research And Engineering Company Reactor for carbon nanotube and nanofiber production
CA3232446A1 (fr) * 2021-10-19 2023-04-27 Lg Chem, Ltd. Appareil de synthese de nanotubes de carbone
CA3232423A1 (fr) * 2021-10-19 2023-04-27 Lg Chem, Ltd. Procede de synthese de nanotubes de carbone

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN120270982A (zh) * 2025-04-08 2025-07-08 江西中科景合新能源科技股份有限公司 一种均匀控温的碳纳米管生产方法

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