WO2022120472A1 - Nanotubes de nitrure de bore et leur procédé de production - Google Patents

Nanotubes de nitrure de bore et leur procédé de production Download PDF

Info

Publication number
WO2022120472A1
WO2022120472A1 PCT/CA2021/051752 CA2021051752W WO2022120472A1 WO 2022120472 A1 WO2022120472 A1 WO 2022120472A1 CA 2021051752 W CA2021051752 W CA 2021051752W WO 2022120472 A1 WO2022120472 A1 WO 2022120472A1
Authority
WO
WIPO (PCT)
Prior art keywords
boron
bnnts
gas stream
nitrogen
gas
Prior art date
Application number
PCT/CA2021/051752
Other languages
English (en)
Inventor
Xavier Cauchy
Original Assignee
Tekna Plasma Systems Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tekna Plasma Systems Inc. filed Critical Tekna Plasma Systems Inc.
Priority to JP2023534711A priority Critical patent/JP2023553897A/ja
Priority to CA3204686A priority patent/CA3204686A1/fr
Publication of WO2022120472A1 publication Critical patent/WO2022120472A1/fr

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
    • C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
    • C01B21/0641—Preparation by direct nitridation of elemental boron
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
    • C01P2004/13—Nanotubes

Definitions

  • This application generally relates to the field of boron nitride nanotubes and processes for producing boron nitride nanotubes.
  • BNNTs Boron nitride nanotubes
  • BNNTs are one-dimensional nanomaterials composed of boron and nitrogen covalently bonded in a honeycomb lattice. Owing to the unique atomic structure, BNNTs have numerous advantageous intrinsic properties such as superior mechanical strength, high thermal conductivity, electrically insulating behavior, piezoelectric property, neutron shielding capability, and oxidation resistance. Therefore, BNNTs have been proposed in various applications, such as BNNT-polymer composites, BNNT-metal composites, and biological applications.
  • BNNT synthesis methods have severe shortcomings, including one or more of having low yield, short tubes, discontinuous production, poor crystallinity (i.e., many defects in molecular structure), and poor alignment.
  • US 9,862,604 describes a process for producing BNNTs (the “HABS” process) that uses h-BN powder as feedstock fed into an inductively coupled plasma torch.
  • the production rate obtained was up to 20 g/h and the process produced BNNT materials with several different morphologies in the same run, including laminated flexible cloth-like materials, fibril-like materials and thin transparent films, which could be recovered at various locations such as on filter surface in a filtration chamber as well as on walls of a pipe located between the reactor and the filtration chamber.
  • the as produced BNNTs materials were characterized with a purity of about 50% and contained non-tubular impurities in the form of unreacted h-BN powder, B-containing polymers and elemental B.
  • the present disclosure relates to boron nitride nanotubes (BNNTs) having an average diameter of about 10 nm or less and having an impurity content of ⁇ 20 wt.%, wherein the impurity content is measured after manufacture of the BNNTs and prior to a purification process.
  • BNNTs boron nitride nanotubes
  • the BNNTs may have one or more of the following characteristics:
  • the impurity content comprises one or more of elemental boron content, h-BN, amorphous BN and BNH derivatives.
  • the impurity content comprises ⁇ 15 wt.%, preferably ⁇ 10 wt.%, preferably ⁇ 5 wt.%, more preferably ⁇ 1 wt.% of elemental boron.
  • the impurity content comprises ⁇ 15 wt.%, preferably ⁇ 10 wt.%, preferably ⁇ 5 wt.%, more preferably ⁇ 1 wt.% of h-BN, amorphous BN and BNH derivatives.
  • the average diameter is from about 2 nm to about 10 nm.
  • the present disclosure also relates to a process for producing boron nitride nanotubes (BNNTs) comprising a) contacting a boron source with a plasma jet to obtain a heated gas stream containing gaseous boron species, wherein the plasma jet is generated from a plasma gas which is free from hydrogen, b) cooling the gas stream to obtain a cooled gas stream, and c) incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • BNNTs boron nitride nanotubes
  • this process may have one or more of the following characteristics:
  • the boron source is in liquid, solid or gaseous form.
  • the boron source includes boron in particulate form and wherein exposing the boron source to the plasma jet causes vaporization of the boron source to obtain the heated gas stream containing gaseous boron species.
  • the boron source includes h-BN in particulate form.
  • plasma of the plasma jet is generated with a plasma gas comprising argon, helium or a combination thereof.
  • the plasma gas further comprises nitrogen (N2).
  • step b) causes nucleation of boron particles.
  • step c) comprises contacting the cooled gas stream with the nitrogen-containing gas under conditions to cause nitridation of the boron particles and form the BNNTs.
  • the nitrogen-containing gas comprises ammonia (NHj).
  • the nitrogen-containing gas further comprises nitrogen (N2).
  • the present disclosure also relates to an apparatus for producing boron nitride nanotubes (BNNTs) comprising a first section comprising an inlet for feeding a boron source to a vaporization zone in the first section, a plasma-generating device for generating a plasma jet in the vaporization zone, the first section being configured for exposing the boron source to the plasma jet to obtain a heated gas stream containing gaseous boron species, wherein the plasma jet is generated from a plasma gas which is free from hydrogen, and a second section in fluid communication with the first section, the second section being configured for cooling the gas stream to obtain a cooled gas stream and incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • BNNTs boron nitride nanotubes
  • this apparatus may have one or more of the following characteristics:
  • the inlet is configured for feeding the boron source in liquid, solid or gaseous form.
  • the boron source includes boron in particulate form, the first section being configured for exposing the boron source to the plasma jet causing vaporization of the boron source.
  • the boron source includes h-BN in particulate form.
  • the plasma-generating device generates the plasma jet from a plasma gas comprising argon, helium or a combination thereof
  • the plasma gas further includes nitrogen (N2).
  • the second section is configured for cooling the gas stream and cause nucleation of boron particles.
  • the second section includes a first portion and a second portion, wherein the first portion causes nucleation of boron particles and wherein the second portion is configured for contacting the cooled gas stream with the nitrogen-containing gas under conditions to cause nitridation of the boron particles and form the BNNTs.
  • the nitrogen-containing gas comprises ammonia (NHj).
  • the nitrogen-containing gas further comprises nitrogen (N2).
  • the present disclosure also relates to a process for producing boron nitride nanotubes (BNNTs) comprising a) providing a heated gas stream containing gaseous boron species, the heated gas being free from hydrogen, b) cooling the gas stream to obtain a cooled gas stream, while controlling the gas stream to obtain a substantially laminar gas flow, and c) incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • BNNTs boron nitride nanotubes
  • this process may have one or more of the following characteristics:
  • step b) further comprises controlling the cooling of the gas stream to obtain a substantially homogeneous cooling along a transverse cross section of the gas stream.
  • step b) causes nucleation of boron particles.
  • step c) comprises contacting the cooled gas stream with the nitrogen-containing gas under conditions to cause nitridation of the boron particles and form the BNNTs.
  • the nitrogen-containing gas comprises ammonia (NHj).
  • the nitrogen-containing gas further comprises nitrogen (N2).
  • the present disclosure also relates to an apparatus for producing boron nitride nanotubes (BNN s) comprising a) a first inlet for feeding a heated gas stream containing gaseous boron species, the heated gas being free from hydrogen, and b) an enclosure in fluid communication with the first inlet, the enclosure being configured for cooling the gas stream to obtain a cooled gas stream and comprising a second inlet for incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • BNN s boron nitride nanotubes
  • this apparatus may have one or more of the following characteristics:
  • the enclosure is configured for controlling the cooling of the gas stream to obtain a substantially homogeneous cooling along a transverse cross section of the gas stream.
  • the enclosure is configured for contacting the cooled gas stream with the nitrogencontaining gas under conditions to cause nitridation of the boron particles and form the BNNTs.
  • the nitrogen-containing gas comprises ammonia (NHj).
  • the nitrogen-containing gas further comprises nitrogen (N2).
  • the present disclosure also relates to an apparatus for producing boron nitride nanotubes (BNNTs) comprising a) a first inlet for feeding a heated gas stream containing gaseous boron species, the heated gas being free from hydrogen, and b) an enclosure in fluid communication with the first inlet, the enclosure being configured for controlling a temperature and a gas flow of the gas stream to obtain a controlled particle size distribution of boron particles and comprising a second inlet for incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • BNNTs boron nitride nanotubes
  • this apparatus may have one or more of the following characteristics:
  • the enclosure is configured for controlling cooling of the gas stream to obtain a substantially homogeneous cooling along a transverse cross section of the gas stream.
  • the enclosure is configured for contacting the cooled gas stream with the nitrogencontaining gas under conditions to cause nitridation of the boron particles and form the BNNTs.
  • the nitrogen-containing gas comprises ammonia (NHj).
  • the nitrogen-containing gas further comprises nitrogen (N2).
  • FIG. 1 shows a cross-sectional view of an apparatus for manufacturing BNNTs including a vaporization section, a nucleation section and a reaction section in accordance with an embodiment of the present disclosure.
  • Fig. 2 shows a cross-sectional view of a plasma generating device for use with the apparatus of Fig. 1.
  • FIG. 3 shows a cross-sectional view of a collecting section for collecting BNNTs in accordance with an embodiment of the present disclosure.
  • FIG. 4 shows a cross-sectional view of an apparatus for manufacturing BNNTs according to Example 1.
  • Fig. 5 shows a schematic view of the apparatus of Fig. 1 that shows a two-dimensional temperature field in various sections of the apparatus.
  • Figs. 6A and 6B show pictures of the inside of a cyclone (Fig. 6A) and of a canister (Fig. 6B) of the apparatus of Fig. 1 after a BNNT manufacturing run. The formation of bridges and fluffy materials indicates that nanotubes were formed.
  • FIG. 7 shows a schematic view of the apparatus of Fig. 1 with gaseous current lines within the different sections of the apparatus, which was obtained with a computational fluid dynamics simulation program using the Asys Fluent software and the following parameters: central argon gas at 24 slpm as well as sheath gas including 22 slpm argon gas and 66 splm nitrogen gas.
  • Fig. 8 shows a schematic view of the apparatus of Fig. 7 with the mass fraction of boron within the different sections of the apparatus.
  • Fig. 9 shows a graph illustrating the time spent by a mass element in the nucleation zone for each streamline of Fig. 7.
  • Pentaborane is believed to be the most likely compound to persist in the reactor since it is the most stable of all the boron hydrides.
  • the detection of the gas being difficult taken together with the fact of the very low potentially lethal concentration threshold makes relying on detection very hazardous to the operator.
  • the BNNTs described herein can be manufactured using a process and apparatus that are designed to avoid formation of hazardous boron hydrides.
  • the process may include providing a heated gas stream of boron species which is hydrogen-free, cooling the gas stream to obtain a cooled gas stream, while controlling the gas stream to obtain a substantially laminar gas flow, and incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • the process may include providing a heated gas stream of boron species which is hydrogen-free, controlling a temperature and a gas flow of the gas stream to obtain a controlled particle size distribution of boron particles, and contacting the boron particles with a nitrogencontaining gas under conditions to obtain the BNNTs.
  • the process may include contacting a boron source with a plasma jet to obtain a heated gas stream containing gaseous boron species, where the plasma jet is generated from a plasma gas which is free from hydrogen.
  • the process may further include cooling the gas stream to obtain a cooled gas stream and incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • the apparatus may include a first section comprising an inlet for feeding a boron source to a vaporization zone in the first section, a plasma-generating device for generating a plasma jet in the vaporization zone, the first section being configured for exposing the boron source to the plasma jet to obtain a heated gas stream containing gaseous boron species, wherein the plasma jet is generated from a plasma gas which is free from hydrogen, and a second section in fluid communication with the first section, the second section being configured for cooling the gas stream to obtain a cooled gas stream and incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • the apparatus may include a first inlet for feeding a heated gas stream containing gaseous boron species, the heated gas being free from hydrogen, and an enclosure in fluid communication with the first inlet, the enclosure being configured for cooling the gas stream to obtain a cooled gas stream and comprising a second inlet for incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • the apparatus may include a first inlet for feeding a heated gas stream containing gaseous boron species, the heated gas being free from hydrogen, and an enclosure in fluid communication with the first inlet, the enclosure being configured for controlling a temperature and a gas flow of the gas stream to obtain a controlled particle size distribution of boron particles and comprising a second inlet for incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • the process and apparatus of the present disclosure may provide one or more advantages over prior art processes and apparatuses.
  • the process of the present disclosure can have one or more of the following advantageous characteristics: can avoid formation of hazardous boron hydrides, can be implemented as a true continuous process, can be highly efficient at generating boron vapor, can produce high yields of BNNTs, can be highly selective to smaller diameter BNNTs, can produce BNNTs that are reasonably pure, can be done at or about atmospheric pressure, can produce BNNTs that are easier to purify and to functionalize chemically, can be more environmentally friendly and can be scalable.
  • the present process is suitable for effective treatment of large quantities of feedstock, thereby allowing the commercial-scale production of small diameter BNNTs in a continuous manner.
  • BNNTs described herein also have advantageous characteristics.
  • the BNNTs of the present disclosure are few walled and have diameters of
  • ⁇ 10 nm for example 1-10 nm, or from about 2 nm to about 10 nm, such as about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9 nm, or about 10 nm, including any value there in-between.
  • the BNNTs may be single-to-few walled and may be greater than 50 microns long.
  • the as-produced BNNTs have low impurity content, for example may have
  • the impurities may include unreacted h-BN (hexagonal- BN) powder, B-containing polymers and elemental B.
  • the impurities may include elemental boron content, h-BN and BNH derivatives (e.g., amorphous B x N y H 2 macromolecules).
  • Such low levels of impurities in as-produced BNNTs are unexpected, particularly in view of existing commercial products for which the levels of impurities are often close to 50 wt.%, for example about 20-25% elemental B and about 20-25 wt.% h-BN and BNH derivatives (Soul-Hee Fee, et al., Purification of Boron Nitride Nanotubes Enhances Biological Applications Properties”, Int. J. of Mol. Sci., 2020, 21, 1529).
  • These impurities are known to hinder as a function of their concentration the ability of BNNTs to enhance performance properties.
  • the BNNTs may have ⁇ 15 wt.%, preferably ⁇ 10 wt.%, preferably ⁇ 5 wt.%, more preferably ⁇ 1 wt.% of elemental boron content.
  • the BNNTs may have ⁇ 15 wt.%, preferably ⁇ 10 wt.%, preferably ⁇ 5 wt.%, more preferably ⁇ 1 wt.% of h-BN and BNH derivatives.
  • the BNNTs may have ⁇ 15 wt.%, preferably ⁇ 10 wt.%, preferably ⁇ 5 wt.%, more preferably ⁇ 1 wt.% of elemental boron content, h-BN and BNH derivatives.
  • Fig. 1 shows a detailed, front elevation view of an embodiment of an apparatus 100 for producing the BNNTs of the present disclosure.
  • the apparatus 100 includes a plasma -generating device 120 producing plasma 112 and an evaporation section 200.
  • the apparatus 100 further includes a nucleation section 300 and a reaction section 400.
  • the apparatus 100 can further include a collecting system 500 as shown in Fig. 3.
  • the apparatus 100 includes other components such as casings, flanges, bolts, and the like, which are believed to be self-explanatory and are not described further herein.
  • the plasma-generating device 120 shown in Fig. 2 is an inductively coupled plasma (ICP) torch, and more specifically a radiofrequency (RF) inductively coupled plasma torch.
  • ICP inductively coupled plasma
  • RF radiofrequency
  • ICP torches examples include those commercialized by TEKNA Plasma Systems, Inc., such as PL-50, PN- 50, PL-35, PN-35, PL-70, PN-70, or PN-100.
  • the plasma-generating device 120 can be another kind of plasma torch, such as a direct current (DC) plasma torch (e.g., those commercialized by Praxair, Oerlikon-Metco, Pyrogenesis and Northwest Mettech), for example.
  • DC direct current
  • the plasma-generating device 120 shown in Fig. 2 includes an outer cylindrical torch body 181, an inner cylindrical plasma confinement tube 110, and at least one induction coil 126 in a coaxial arrangement.
  • the outer cylindrical torch body 181 can be made of a moldable composite material, for example a moldable composite ceramic material.
  • the inner cylindrical plasma confinement tube 110 can be made of ceramic material and is coaxial with the torch body 181.
  • the induction coil 126 is coaxial with and embedded in the torch body 181 to produce a RF (radio frequency) electromagnetic field whose energy ignites and sustains the plasma 112 confined in the plasma confinement tube 110.
  • a power level of the plasma-generating device 120 may, without loss of generality, vary between about 10 kW and about 400 kW for a commercial production scale unit, for example about 20 kW, about 25 kW, about 30 kW, about 35 kW, about 40 kW, about 45 kW, about 50 kW, about 55 kW, about 60 kW, about 65 kW, about 70 kW, about 75 kW, about 80 kW, about 85 kW, about 90 kW, about 95 kW, about 100 kW, and the like.
  • the plasma is produced from a plasma central gas 20 preferably an inert gas, such as argon, helium, or any combinations thereof.
  • the plasma central gas 20 is substantially hydrogen-free to avoid generating harmful levels of boron hydrides compounds.
  • the plasma central gas 20 is typically supplied within the plasma confinement tube 110 through a head 185 of the plasma-generating device 120 at the upper end of the torch body 181.
  • RF current is supplied to the induction coil(s) 126 via power leads (not shown).
  • the plasma central gas 20 can be inserted in the plasma-generating device 120 so that its flow is coaxial with the torch body 181.
  • the plasma central gas 20 can be inserted in the plasma-generating device 120 so that its flow is at an angle with respect to the torch body 181, for example.
  • the apparatus 100 can be configured to inject at least one plasma sheath gas 40 at one or more locations downstream, upstream, or within the plasma confinement tube 110.
  • the head 185 includes an inlet for the plasma sheath gas 40 adjacent an inlet for the plasma central gas 20.
  • the plasma sheath gas 40 can stabilize the plasma discharge at the center of the tube and can protect the plasma confinement tube 110 from high heat fluxes emanating from the plasma discharge.
  • the plasma 112 can be generated from the plasma central gas 20 alone or from both the plasma central gas 20 and plasma sheath gas 40.
  • the plasma sheath gas 40 may be any plasma sheath gas known in the art, except for hydrogen — in other words, similar to the case of the plasma central gas 20, the plasma sheath gas 40 is also substantially hydrogen-free to avoid generating harmful levels of boron hydrides.
  • the plasma sheath gas comprises argon (Ar), nitrogen (N2), or a mixture thereof.
  • the apparatus 100 further includes a feedstock injector 114 to inject a boron-containing precursor material 130 (sometimes referred-to as “boron-containing feedstock”).
  • the boron- containing feedstock 130 may be in liquid, gas or powder form.
  • the feedstock injector 114 may be coaxial with the torch body 181 and configured to inject the precursor material 130 into the plasma 112.
  • the boron-containing feedstock 130 may be continuously injected into the high temperature induction plasma 112 to form a heated gas stream containing gaseous boron species.
  • the feedstock evaporates in the plasma 112 releasing boron vapors into the evaporation section 200.
  • Boron nitride (BN) powders may be preferred for many methods. In some methods, BN releases nitrogen during vaporization, and may require the apparatus 100 to have additional heating capacity. Cubic BN powders may be suitable, although this material is quite expensive rendering its use for making BNNTs less attractive. Both B and BN powders are available in dozens of industrial grades. Typically, smaller particles vaporize more easily.
  • the precursor material 130 can be mixed with a carrier gas prior to, concomitantly with, or after its injection in the apparatus 100 through the injector 114.
  • the carrier gas is typically a gas that does not react with the precursor material 130.
  • the carrier gas can be the same type of gas as the plasma central gas 20 and/ or can include a mixture of gases and can facilitate transportation of the precursor material 130. Similar to the plasma central gas 20, the carrier gas is also substantially hydrogen-free to avoid generating harmful levels of boron hydrides.
  • the plasma-generating device 120 is in fluid communication with the evaporation section 200, through an exit outlet (e.g., an exit nozzle) as shown in Fig. 2.
  • the plasma-generating device 120 is configured for generating a plasma jet from the plasma 112 that, upon contacting the precursor material 130, heats the latter at a temperature that allows the production of a heated gas stream containing gaseous boron species in the evaporation section 200. This heating may be extended to a zone downstream, defined by the plasma afterglow 146, which is a portion of the plasma jet generated from the plasma 112 that extends below the plasma-generating device 120 along a longitudinal axis of the apparatus 100.
  • the evaporation section 200 is configured to define an elongated vaporization chamber 250.
  • the evaporation section 200 also causes the heated gas stream containing gaseous boron species in the evaporation section 200 to homogenize thus reducing presence of gas gradients that could otherwise form nucleation pockets and disrupt the process described herein.
  • the evaporation section 200 can be sized and configured to maintain a temperature in the range of about 3000 K to about 3500 K in the gases surrounding the plasma afterglow 146 as shown for example in Fig. 5.
  • FIG. 5 is a schematic view of an apparatus 100 that shows a two-dimensional temperature field in various sections of the apparatus 100 when operated with an argon induction plasma, a radio frequency power supply with an oscillator frequency of 4 MHz and a plate power of 50 kW.
  • vaporization requires that the dispersed boron temperature be held above its vaporization temperature for a time enough to convert it to gas.
  • the duration is dependent on at least the size of the feedstock particles and the local temperature, but typically may be on the order of about 1 millisecond to 100s of milliseconds.
  • the apparatus 100 may further include an isolating material 230 that encloses at least a portion of the evaporation section 200 to control the temperature within the elongated vaporization chamber 250 and/ or that encloses at least a portion of the nucleation section 300 to also control the temperature within a nucleation chamber 350, which will be further described below.
  • the evaporation section 200 is in fluid communication with the nucleation section 300.
  • the nucleation section 300 is configured to allow a substantially homogeneous cooling across different gas streamlines (corresponding to eventual different boron particles paths) and allow controlled nucleation and growth of boron particles.
  • the thermal history of a first particle on a first gas stream line (or particle path) is substantially identical to that one of a second particle on a second and different gas stream line (or second particle path).
  • the nucleation section 300 is sized and configured to cause cooling of the gas containing boron species to reach a cooled T2 temperature from an initial T1 temperature.
  • the T1 temperature may be but without being limited to a temperature above 3000 K and the T2 temperature may be but without being limited to a temperature of from about 1400K to about 2500 K.
  • T1 may be about 3200 K and T2 may be about 2700 K, as shown in Fig. 5.
  • the nucleation section 300 is configured such that the nucleation chamber 350 has a tapered shape with a cross-section that increases in diameter along the longitudinal axis of the apparatus 100 extending away from the evaporation section 200.
  • the nucleation chamber 350 allows a substantially controlled homogeneous cooling of the reactant gases across different gas streamlines, in particular within a nucleation zone 380 defined between T2 and Tl, which minimizes formation of byproducts and affords better control of physiochemical properties of the resulting nanotubes.
  • the boron vapor cooling may be locally induced by a condenser, such as described in U.S. Pat. No. 8,753,578 (which is herein incorporated by reference).
  • the condenser can take many forms, such as, for example, a cooled copper rod or tungsten wire or networks or grids thereof. Primary considerations are that the condenser can survive the ambient temperature of the boron nucleation section 300 and that the flow stream can pass readily over/ through it.
  • metal catalysts are pure metals, metal oxides, metal salts or any mixture thereof. Mixed metal oxides are of note.
  • the metal catalyst may contain, for example, nickel, iron, cobalt, cerium, yttrium, molybdenum or any mixture thereof. Such metal catalysts are generally known in the art.
  • carbon-doped BNNTs e.g., B-C-N nanotubes, BCNNT
  • the one or more sources of carbon may be in any physical form, for example, a solid, liquid or gas.
  • Some examples of carbon sources are elemental carbon (e.g. graphitic carbons, amorphous carbons), carbon monoxide, carbon dioxide, hydrocarbons (e.g. acetylene, methane), or any mixture thereof.
  • doping of boron nitride nanotubes with carbon permits band gap engineering to tailor electronic and/ or thermal properties of the nanotubes for specific applications.
  • the nucleation section 300 is in fluid communication with the reaction section 400. Initial cooling of the vapors in the nucleation section 300 permits nucleation of boron particles that can then react with nitrogen species downstream in the reaction section 400 to start the formation of BNNTs.
  • the reaction section 400 further may include one or more inlets for incorporating nitrogen-containing gas in the reaction chamber 450 to contact the boron particles and form the BNNTs.
  • the nitrogen-containing gas may include ammonia (NHj) and may be injected into the reaction chamber 450 downstream from the nucleation section 300 in admixture with or without a carrier gas.
  • Carrier gases can be suitably inert gases, for example argon, helium or a mixture thereof and/ or may include another nitrogen-containing gas, such as nitrogen (N2).
  • BNNTs continue to grow in their passage through the reaction chamber 450. As the reaction mixture cools further down in the reaction chamber 450, the continued growth of the BNNTs is ultimately terminated.
  • the reaction chamber 450 can be cooled with a cooling fluid jacket in which cooling fluid flows, for example water or a cooling gas.
  • the reaction section 400 may be configured to allow injection of a gas pre-heated to a desired temperature into the reaction chamber 450 that may extend over at least a longitudinal portion of the reaction chamber 450 to assist in maintaining a temperature suitable for BNNTs synthesis.
  • the injection of hot gases allows a flatter temperature profile along the longitudinal axis, and therefore a longer residence time at a temperature suitable for producing BNNTs.
  • the gas injected into the reaction chamber 450 includes nitrogen (N2). Structural specifics for injecting such gases are described, for example, in PC / CA2020/051365 (the contents of which are hereby incorporated by reference) and for conciseness sake will thus not be further described here.
  • the temperature in the reaction section 400 can be above the melting point of boron and below the boiling point of boron.
  • the temperature in the reaction section 400 can be in the range of from about 1000 °C to about 2000 °C, as shown in Fig. 5. In some embodiments, the temperature may gradually cool down along the longitudinal axis to gradually terminate the reaction.
  • reaction section 400 is in fluid communication with a collecting section where BNNTs are collected.
  • the BNNTs are collected using known collecting systems, as described in for example US 9,862,604 (which is incorporated herein by reference), which makes use of a vacuum pump to draw BNNT-laden gases through porous filters that capture the BNNTs.
  • the collecting system may include a collecting chamber in fluid communication with the reaction chamber through a pipe.
  • a vacuum pump connected to vacuum port draws the BNNTs- laden gases through porous filters disposed in the collecting chamber, whereupon the BNNTs are deposited on the filters and on internal walls of the pipe while the gases are drawn out. BNNTs can then be collected off the filters and the pipe.
  • the BNNTs are collected using collecting system 500 as described in Fig. 3.
  • the collecting system 500 may include an inlet in fluid communication with the reaction chamber 450, where the inlet allows BNNTs-laden gas stream 605 to flow through a feeding conduit 610.
  • a vacuum pump can be connected downstream the collecting system 500 to draw BNNTs-laden gases 605 through the collecting system 500, for example.
  • the collecting system 500 includes a feeding mechanism 640 that linearly feeds a screen or wire mesh filter 625 from a roll 615 such that at least a portion of the filter mesh 625 intersects the stream 605 through the feeding conduit 610.
  • the screen or wire mesh filter 625 may have 5 mm or less spacing (pores), for example less than 1 mm, for allowing the stream 605 to go through while capturing BNNTs thereon.
  • the screen or wire mesh filter 625 may be made from a suitable material, for example stainless steel wire.
  • the screen or wire mesh filter 625 When the portion of the screen or wire mesh filter 625 is linearly fed through the feeding conduit 610, the screen or wire mesh filter 625 intersects with streams of the BNNTs-laden gases 605 such that BNNTs deposit on the screen or wire mesh filter 625 to form a BNNTs-loaded screen or wire mesh filter 635.
  • the collecting system 500 may further include a recovery mechanism 620 that is disposed on one side of the feeding conduit 610 across from the feeding mechanism 640.
  • the feeding mechanism 640 may thus be configured to feed the screen or wire mesh filter 625 from the roll 615 along a transverse direction (shown with the arrow in Fig. 3) towards the recovery mechanism 620, where the BNNTs loaded screen or wire mesh filter 625 is loaded into roll 645.
  • the collecting system 500 can include a redundant system where the feeding mechanism 640 and the recovery mechanism 620 together form a recovery structure A and where the collecting system 500 includes a recovery structure B that can be substantially identical to the recovery structure A.
  • the recovery structure B can be located downstream from the recovery structure A.
  • the recovery structure B can be located upstream from the recovery structure A.
  • the recovery structure B may include a feeding mechanism 615’ and a recovery mechanism 620’ that together operate substantially the same way as the corresponding mechanisms 615, 620 in the recovery structure A.
  • an operator can open / close valve system 630 on the recovery structure A and open / close valve system on the recovery system B to switch from one recovery structure to the other.
  • an operator can open valve system 630 on the recovery structure A to operate this recovery structure while closing valve system 630’ on the recovery system B to turn the latter off.
  • Such may allow, for example, the operator to operate the recovery structure A while loading / unloading a roll of screen or wire mesh from the feeding mechanism 615’ and/or recovery mechanism 620’.
  • the collecting system 500 may include one or more recovery structures and/or one or more feeding conduit(s) 610 each having its own collecting system.
  • the formation of BNNTs in the present disclosure is at least in part controlled by the size of the boron nanoparticles formed upstream of the reaction section. Therefore, if one is looking to maximize the amount of particles with the correct size, it is advantageous to ensure having a tight particle size distribution (PSD) and that this PSD is within the correct range.
  • PSD particle size distribution
  • the apparatus 100 is advantageously designed to provide a controlled environment, conducive to homogeneous nucleation and uniform growth.
  • Fig. 8 shows the mass fraction of boron in the apparatus 100 implementing the process described herein, with the nucleation zone 380 shown within the dotted lines. Initially, and until the end of the so-called “uniformization” cylindrical zone 250, the boron species are highly concentrated close to the inlet C of the cylindrical zone 250 and on the axis X of the apparatus 100. However, this concentration quickly fades and the deviation of concentration over the the cylindrical zone 250 decreases by a factor of about 4 between the inlet C and the outlet D of the cylindrical zone 250. The concentration then becomes substantially uniform over the nucleation zone 380.
  • the size of the nanoparticles is attributable to the amount of vapor which condenses on the particles.
  • a dynamic process one can relate to the time spent in the nucleation zone. The nascent particles will be entrained along the streamlines, so it is a matter of determining the time spent by a mass element in the nucleation zone for each streamline to assess the uniformity of the nucleation process.
  • Fig. 9 is a graph that shows this time for the example shown in Fig. 7 and Fig. 8.
  • the herein described process for producing boron nitride nanotubes may thus include a) contacting a boron source with a plasma jet to obtain a heated gas stream containing gaseous boron species, wherein the plasma jet is generated from a plasma gas which is free from hydrogen, b) cooling the gas stream to obtain a cooled gas stream, and c) incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • the herein described process for producing boron nitride nanotubes may thus include a) providing a heated gas stream containing gaseous boron species, the heated gas being free from hydrogen, b) cooling the gas stream to obtain a cooled gas stream, while controlling the gas stream to obtain a substantially laminar gas flow, and c) incorporating a nitrogen-containing gas into the cooled gas stream under conditions to obtain the BNNTs.
  • the herein described process for producing boron nitride nanotubes may thus include a) providing a heated gas stream of boron species which is hydrogen-free, b) controlling a temperature and a gas flow of the gas stream to obtain a controlled particle size distribution of boron particles, and c) contacting the boron particles with a nitrogencontaining gas under conditions to obtain the BNNTs.
  • the herein described process for producing boron nitride nanotubes may thus include a) providing a heated gas stream of boron species which is hydrogen-free, b) controlling a temperature and a gas flow of the gas stream to obtain a controlled particle size distribution of boron particles, and c) contacting the boron particles with a nitrogencontaining gas under conditions to obtain the BNNTs.
  • the average particle size refers to an average value of the particle sizes.
  • the average particle size refers to D50, i.e., the particle diameter at the 50% point on a particle size distribution curve when the total volume is 100%.
  • the term “substantially” refers to a degree of deviation that is sufficiently small so as to not measurably detract from the identified property (e.g., sphericity). The exact degree of deviation allowable may in some cases depend on the specific context.
  • plasma refers to a state of matter in which an ionized gaseous substance becomes highly electrically conductive to the point that long-range electric and magnetic fields dominate the behavior of the matter. Plasma is typically artificially generated by heating neutral gases or by subjecting that gas to a strong electromagnetic field.
  • plasma torch refers to a device for generating a direct flow of plasma.
  • plasma arc refers to a device for generating a direct flow of plasma.
  • plasma cutter refers to a device for generating a direct flow of plasma.
  • the abbreviation “pm” designates micrometers and the abbreviation “nm” designates nanometers.
  • PSD particle size distribution
  • the most easily understood method of determination is sieve analysis, where powder is separated on sieves of different sizes.
  • the PSD is defined in terms of discrete size ranges: e.g. a PSD of between 45 pm and 53 pm, when sieves of these sizes are used.
  • the PSD is usually determined over a list of size ranges that covers nearly all the sizes present in the sample.
  • Example 1 Comparative production of BNNTs with a prior art process
  • BNNTs were produced using an ICP plasma prior art process, which includes hydrogen gas in the plasma.
  • a total of 50 g of h-BN feedstock was fed over one hour for an average feed rate of 0.8 g/min into a 120 kW ICP plasma source (Pekna Plasma Systems Inc., Canada) in an apparatus as shown in Fig. 4.
  • This apparatus includes a fishtail section and a porous section.
  • a ceramic tube was inserted at the torch exit to create a hot region to promote feedstock vaporization and gases mixing. At the exit of the ceramic tube, a quick decrease in temperature initiates nucleation and nanoparticles formation.
  • IDTH immediate danger to human life or health
  • STEL short term exposure limit
  • TWA time weighted average
  • Example 3 the process of Example 1 was reproduced but using a 15 kW ICP plasma source (Tekna Plasma Systems Inc., Canada). The operating parameters are set forth in Table 3.
  • the present inventors propose that the presence of hydrogen in the plasma gas may cause the formation of NH species and BxHy species, where these species then convert into H 2 , B x H y and N 2 species, followed by quenching and formation of metallic boron nanoparticles and ammonia gas (NH 3 ), followed by exothermic nitridation of the nanoparticles thus forming BNNTs.
  • NH 3 metallic boron nanoparticles and ammonia gas
  • BNNT were obtained using a plasma in absence of hydrogen in accordance with an embodiment of the present disclosure.
  • a TekNano-15 plasma apparatus (Tekna Plasma Systems, Inc., Canada) was modified to accommodate the introduction of controlled amounts of ammonia gas downstream from the plasma afterglow.
  • ammonia gas was introduced in the porous section of the system, without any hydrogen injected into the plasma generating device.
  • This serves a dual purpose: (1) all boron particles are expected to be fully nucleated at the point of ammonia gas introduction, such that no more atomic boron can be available to react with hydrogen that would dissociate from the ammonia, thus suppressing the risk of boron hydrides formation and (2) since no hydrogen is introduced in the torch, there is no formation of hazardous borane hydrides.
  • the feedstock was MK-hBN-N70 at a feed rate of 0.7 g/min with 3 slpm Ar gas as a carrier. The experiment was conducted for 50 min during which 34 grams of feedstock were fed.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Inorganic Fibers (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

La présente divulgation concerne des nanotubes de nitrure de bore (BNNT) tels que produits ayant de faibles teneurs en impuretés, un procédé et un appareil pour leur fabrication. Les BNNT ont un diamètre moyen d'environ 10 nm ou moins et ont une teneur en impuretés ≤ 20 % en poids, la teneur en impuretés étant mesurée après la fabrication des BNNT et avant un procédé de purification. Le procédé et l'appareil sont conçus pour fournir un courant de gaz chauffé d'espèces de bore qui est exempt d'hydrogène, refroidir le courant de gaz et incorporer un gaz contenant de l'azote dans le courant de gaz refroidi dans des conditions permettant d'obtenir les BNNT. Le procédé et l'appareil permettent ainsi de fabriquer des BNNT tout en évitant la formation d'hydrures de bore dangereux.
PCT/CA2021/051752 2020-12-08 2021-12-07 Nanotubes de nitrure de bore et leur procédé de production WO2022120472A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2023534711A JP2023553897A (ja) 2020-12-08 2021-12-07 窒化ホウ素ナノチューブ及びそれを生成するための方法
CA3204686A CA3204686A1 (fr) 2020-12-08 2021-12-07 Nanotubes de nitrure de bore et leur procede de production

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US202063122817P 2020-12-08 2020-12-08
US63/122,817 2020-12-08

Publications (1)

Publication Number Publication Date
WO2022120472A1 true WO2022120472A1 (fr) 2022-06-16

Family

ID=81973028

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CA2021/051752 WO2022120472A1 (fr) 2020-12-08 2021-12-07 Nanotubes de nitrure de bore et leur procédé de production

Country Status (3)

Country Link
JP (1) JP2023553897A (fr)
CA (1) CA3204686A1 (fr)
WO (1) WO2022120472A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150125374A1 (en) * 2013-11-01 2015-05-07 Bnnt, Llc Induction-coupled plasma synthesis of boron nitride nanotubes
WO2015164777A1 (fr) * 2014-04-24 2015-10-29 Bnnt, Llc Fibres de nanotubes de nitrure de bore en continu
KR102143989B1 (ko) * 2019-10-25 2020-08-12 재단법인 철원플라즈마 산업기술연구원 질화붕소 나노튜브 제조 장치

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150125374A1 (en) * 2013-11-01 2015-05-07 Bnnt, Llc Induction-coupled plasma synthesis of boron nitride nanotubes
WO2015164777A1 (fr) * 2014-04-24 2015-10-29 Bnnt, Llc Fibres de nanotubes de nitrure de bore en continu
KR102143989B1 (ko) * 2019-10-25 2020-08-12 재단법인 철원플라즈마 산업기술연구원 질화붕소 나노튜브 제조 장치

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
FATHALIZADEH AIDIN, PHAM THANG, MICKELSON WILLIAM, ZETTL ALEX: "Scaled Synthesis of Boron Nitride Nanotubes, Nanoribbons, and Nanococoons Using Direct Feedstock Injection into an Extended-Pressure, Inductively-Coupled Thermal Plasma", NANO LETTERS, AMERICAN CHEMICAL SOCIETY, US, vol. 14, no. 8, 13 August 2014 (2014-08-13), US , pages 4881 - 4886, XP055939837, ISSN: 1530-6984, DOI: 10.1021/nl5022915 *
KEUN SU KIM; MYUNG JONG KIM; CHEOL PARK; CATHARINE C FAY; SANG-HYON CHU; CHRISTOPHER T KINGSTON; BENOIT SIMARD: "Scalable manufacturing of boron nitride nanotubes and their assemblies: a review", SEMICONDUCTOR SCIENCE TECHNOLOGY, IOP PUBLISHING LTD, GB, vol. 32, no. 1, 1 December 2016 (2016-12-01), GB , pages 013003, XP020311807, ISSN: 0268-1242, DOI: 10.1088/0268-1242/32/1/013003 *
KIM KEUN SU, SIGOUIN GABRIELA, CHO HYUNJIN, COUILLARD MARTIN, GALLERNEAULT MARY, MOON SE YOUN, LEE HUN SU, KIM MYUNG JONG, JANG SE: "Insight into BN Impurity Formation during Boron Nitride Nanotube Synthesis by High-Temperature Plasma", ACS OMEGA, ACS PUBLICATIONS, US, vol. 6, no. 41, 19 October 2021 (2021-10-19), US , pages 27418 - 27429, XP055939844, ISSN: 2470-1343, DOI: 10.1021/acsomega.1c04361 *
YU JUN; LI BILL C.; ZOU JIN; CHEN YING: "Influence of nitriding gases on the growth of boron nitride nanotubes", JOURNAL OF MATERIAL SCIENCE, KLUWER ACADEMIC PUBLISHERS, DORDRECHT, vol. 42, no. 11, 1 June 2007 (2007-06-01), Dordrecht , pages 4025 - 4030, XP036678438, ISSN: 0022-2461, DOI: 10.1007/s10853-006-0381-4 *

Also Published As

Publication number Publication date
CA3204686A1 (fr) 2022-06-16
JP2023553897A (ja) 2023-12-26

Similar Documents

Publication Publication Date Title
US8013269B2 (en) Induction plasma synthesis of nanopowders
US8859931B2 (en) Plasma synthesis of nanopowders
US7967891B2 (en) Method producing metal nanopowders by decompositon of metal carbonyl using an induction plasma torch
US7846414B2 (en) Method for producing carbon nanotubes using a DC non-transferred thermal plasma torch
US20100300358A1 (en) Apparatus for producing single-wall carbon nanotubes
US7438880B2 (en) Production of high purity ultrafine metal carbide particles
EP3077100B1 (fr) Procédé et appareil de production de nanotubes de carbone
Lin et al. Synthesis of Ni nanoparticles with controllable magnetic properties by atmospheric pressure microplasma assisted process
Kim et al. Thermal plasma synthesis of ceramic nanomaterials
WO2022120472A1 (fr) Nanotubes de nitrure de bore et leur procédé de production
Jin et al. Spheroidization of molybdenum powder by radio frequency thermal plasma
Bai et al. RF Plasma Synthesis of Nickel Nanoparticles from Liquid Precursor
KIM et al. Patent 2877060 Summary
WO2007044013A1 (fr) Procédé de préparation de nanoparticules de métal de transition superparamagnétiques

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21901748

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 3204686

Country of ref document: CA

WWE Wipo information: entry into national phase

Ref document number: 2023534711

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21901748

Country of ref document: EP

Kind code of ref document: A1