WO2022046297A1 - Système réacteur à micro-ondes renfermant un plasma à auto-allumage - Google Patents

Système réacteur à micro-ondes renfermant un plasma à auto-allumage Download PDF

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Publication number
WO2022046297A1
WO2022046297A1 PCT/US2021/041110 US2021041110W WO2022046297A1 WO 2022046297 A1 WO2022046297 A1 WO 2022046297A1 US 2021041110 W US2021041110 W US 2021041110W WO 2022046297 A1 WO2022046297 A1 WO 2022046297A1
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plasma
carbon
particles
reactor system
microwave
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PCT/US2021/041110
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English (en)
Inventor
David Tanner
Daniel Cook
Bryce H. Anzelmo
Ranjeeth Kalluri
Michael W. Stowell
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Lyten, Inc.
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Priority claimed from US17/008,401 external-priority patent/US20210053829A1/en
Application filed by Lyten, Inc. filed Critical Lyten, Inc.
Publication of WO2022046297A1 publication Critical patent/WO2022046297A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32192—Microwave generated discharge
    • H01J37/32211—Means for coupling power to the plasma
    • H01J37/32229—Waveguides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32192—Microwave generated discharge
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32357—Generation remote from the workpiece, e.g. down-stream
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/3244—Gas supply means
    • H01J37/32449—Gas control, e.g. control of the gas flow
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32623—Mechanical discharge control means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32798—Further details of plasma apparatus not provided for in groups H01J37/3244 - H01J37/32788; special provisions for cleaning or maintenance of the apparatus
    • H01J37/32807—Construction (includes replacing parts of the apparatus)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D45/00—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces
    • B01D45/12—Separating dispersed particles from gases or vapours by gravity, inertia, or centrifugal forces by centrifugal forces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/66—Regeneration of the filtering material or filter elements inside the filter
    • B01D46/70—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter
    • B01D46/71—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter with pressurised gas, e.g. pulsed air
    • 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
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30

Definitions

  • Chemical processing systems configured to propagate microwave energy to generate a plasma can produce carbon nanoparticles and aggregates, such as the materials described in U.S. Patent Application No. 15/594,032, entitled “Carbon Allotropes,” and in U.S. Patent Application No. 15/711,620 entitled “Seedless Particles With Carbon Allotropes,” which are assigned to the same assignee as the present application, and are incorporated herein by reference herein for all purposes.
  • the form-factors of the materials described herein are particles (such as nanoparticles or aggregates).
  • the form-factors are not films, which are arranged on objects or substrates.
  • the carbon particles described herein can be core-less or seedless (such as do not contain a core or a seed of a material other than carbon).
  • the carbon aggregates described herein can be characterized by a size that is substantially larger than comparable prior art particles.
  • Graphene can contain fewer than 15 layers of carbon atoms, or fewer than 10 layers of carbon atoms, or fewer than 7 layers of carbon atoms, or fewer than 5 layers of carbon atoms, or fewer than 3 layers of carbon atoms, or contains a single layer of carbon atoms, or contains from 1 to 10 layers of carbon atoms, or contains from 1 to 7 layers of carbon atoms, or contains from 1 to 5 layers of carbon atoms.
  • Few layer graphene (FLG) can contain from 2 to 7 layers of carbon atoms.
  • Many layer graphene (MLG) can contain from 7 to 15 layers of carbon atoms.
  • fullerene implies a molecule of carbon in the form of a hollow sphere, ellipsoid, tube, or other shapes.
  • Spherical fullerenes can also be referred to as Buckminsterfullerenes, or buckyballs.
  • Cylindrical fullerenes can also be referred to as carbon nanotubes.
  • Fullerenes are similar in structure to graphite, which is composed of stacked graphene sheets of linked hexagonal rings. Fullerenes may also contain pentagonal (or sometimes heptagonal) rings.
  • multi-walled fullerene implies fullerenes with multiple concentric layers.
  • amorphous carbon implies a carbon allotrope that has minimal or no crystalline structure.
  • One method for characterizing amorphous carbon is through the ratio of sp 2 to sp 3 hybridized bonds present in the material.
  • the sp 2 to sp 3 ratios can be determined by comparing the relative intensities of various spectroscopic peaks (including EELS, XPS, and Raman spectroscopy) to those expected for carbon allotropes with sp 2 or sp 3 hybridization.
  • aggregate implies a plurality of particles or nanoparticles that are connected together by Van der Waals forces, by covalent bonds, by ionic bonds, by metallic bonds, or by other physical or chemical interactions. Aggregates can vary in size considerably, but in general are larger than about 500 nm.
  • particle or “particles” imply any size particles, including nanoparticles and aggregates.
  • FIG. 1A shows a schematic of graphite, where carbon forms multiple layers of a two-dimensional, atomic-scale, hexagonal lattice in which one atom forms each vertex.
  • Graphite as shown here, is made of single layers of graphene.
  • Figure IB shows a schematic of a carbon nanotube, where carbon atoms form a hexagonal lattice that is curved into a cylinder. Carbon nanotubes can also be referred to as cylindrical fullerenes.
  • the carbon nanoparticles and aggregates produced by any one or more of the reactors or reactor configurations described herein can be characterized by a well-ordered structure with high purity as illustrated by an idealized carbon nanoparticle 100 shown in Figure IE.
  • the carbon allotrope in Figure IE contains two connected multi-walled spherical fullerenes (MWSFs) 101 and 102 with layers of graphene 103 coating the connected MWSFs 101 and 102.
  • the allotrope shown in Figure IE is also core-less (such as does not contain a core of a material other than carbon at the center of the spherical fullerene).
  • the nanoparticle shown in Figure IE has a relatively high uniformity since the ratio of MWSFs to graphene is high, is well-ordered since there are no point defects (such as missing carbon atoms) and no distorted carbon lattices.
  • the nanoparticle also has a high purity since there are no elements (such as a core of impurities) other than carbon, in contrast with low uniformity mixtures of MWSFs mixed with other carbon allotropes, poorly-ordered MWSFs with many point defects and distorted lattices, and low purity MWSFs (such as with seed particles at the core).
  • the connected MWSFs can contain a core.
  • the core can be a void, or a carbon-based material that is not an MWSF (such as amorphous carbon), or a seed that is not carbon-based.
  • the aggregates described herein can contain graphene, such as containing up to 15 layers, and one or more other carbon allotropes in addition to graphene, and have a ratio of graphene to other carbon allotropes from 20% to 80%, a high degree of order (such as a Raman signature with the ratio of the intensity of the 2D-mode peak to the G-mode peak greater than 0.5), and a high purity (such as the ratio of carbon to other elements, other than H, is greater than 99.9%).
  • graphene such as containing up to 15 layers
  • a ratio of graphene to other carbon allotropes from 20% to 80%
  • a high degree of order such as a Raman signature with the ratio of the intensity of the 2D-mode peak to the G-mode peak greater than 0.5
  • a high purity such as the ratio of carbon to other elements, other than H, is greater than 99.9%
  • the ratio graphene to graphite can be from 5% to 95%, or from 10% to 90%, or from 10% to 80% or from 10% to 60%, or from 10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to 90%, or from 60% to 90%, or from 80% to 90%, or greater than 5%, or greater than 10%, or greater than 20%, or greater than 30%, or greater than 40%, or greater than 50%, or greater than 60%, or greater than 70%, or greater than 80%, or greater than 90%.
  • the particles can be produced using the methods described herein contain graphite and graphene, and do not contain a core composed of impurity elements other than carbon. In some cases, the aggregates of the particles have large diameters (such as greater than 10 microns across).
  • the aggregates described herein can contain graphene, MWSFs or connected MWSFs, and optionally graphite, and have a ratio of graphene to MWSF from 20% to 80%, a high degree of order (such as a Raman signature with ratio of the intensities of the D-mode peak to G-mode peak from 0.95 to 1.05), and a high purity (such as the ratio of carbon to other elements, other than H, is greater than 99.9%).
  • a ratio of graphene to MWSF from 20% to 80%
  • a high degree of order such as a Raman signature with ratio of the intensities of the D-mode peak to G-mode peak from 0.95 to 1.05
  • a high purity such as the ratio of carbon to other elements, other than H, is greater than 99.9%.
  • the ratio of graphene to MWSFs or connected MWSFs can be from 5% to 95%, or from 10% to 90%, or from 10% to 80% or from 10% to 60%, or from 10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to 90%, or from 60% to 90%, or from 80% to 90%, or greater than 5%, or greater than 10%, or greater than 20%, or greater than 30%, or greater than 40%, or greater than 50%, or greater than 60%, or greater than 70%, or greater than 80%, or greater than 90%.
  • the particles produced using the methods described herein contain MWSFs or connected MWSFs, and the MWSFs do not contain a core composed of impurity elements other than carbon.
  • the aggregates of the particles have large diameters (such as greater than 10 microns across).
  • the aggregates described herein can contain graphene, amorphous carbon, and optionally graphite, and have a ratio of graphene to amorphous carbon from 1% to 10%, and have a high purity (such as the ratio of carbon to other elements, other than H, is greater than 99.9%).
  • the ratio of graphene to amorphous carbon can be from 5% to 95%, or from 1% to 90%, or from 1% to 80%, or from 1% to 60%, or from 1% to 40%, or from 1% to 20%, 10% to 90%, or from 10% to 80% or from 10% to 60%, or from 10% to 40%, or from 10% to 20%, or from 20% to 40%, or from 20% to 90%, or from 40% to 90%, or from 60% to 90%, or from 80% to 90%, or greater than 5%, or greater than 10%, or greater than 20%, or greater than 30%, or greater than 40%, or greater than 50%, or greater than 60%, or greater than 70%, or greater than 80%, or greater than 90%.
  • the particles produced using the methods described herein can contain amorphous carbon, and do not contain a core composed of impurity elements other than carbon. In some cases, the aggregates of the particles have large diameters (such as greater than 10 microns across).
  • the carbon material can have a ratio of carbon to other elements, except hydrogen, greater than 60%, or greater than 70%, or greater than 80%, or greater than 90%, or greater than 99%, or greater than 99.5%, or greater than 99.7%, or greater than 99.9%, or greater than 99.95%.
  • the median size of the carbon aggregates can be from 1 micron to 50 microns, or from 2 microns to 20 microns, or from 5 microns to 40 microns, or from 5 microns to 30 microns, or from 10 microns to 30 microns, or from 10 microns to 25 microns, or from 10 microns to 20 microns.
  • the size distribution of the carbon aggregates can have a 10th percentile from 1 micron to 10 microns, or from 1 micron to 5 microns, or from 2 microns to 6 microns, or from 2 microns to 5 microns.
  • the size of the particles that make up the aggregates can vary in size and can be smaller than 10 nm or up to hundreds of nanometers in size.
  • the nanoparticles that make up the aggregates have an average diameter in a range from 5 to 500 nm, or from 5 to 250 nm, or from 5 to 100 nm, or from 5 to 50 nm, or from 10 to 500 nm, or from 10 to 250 nm, or from 10 to 100 nm, or from 10 to 50 nm, or from 40 to 500 nm, or from 40 to 250 nm, or from 40 to 100 nm, or from 50 to 500 nm, or from 50 to 250 nm, or from 50 to 100 nm.
  • the size of aggregates can be measured using TEM images.
  • the size of the aggregates can be measured using a laser particle size analyzer (such as a Fritsch Analysette 22 MicroTec plus).
  • the surface area of the carbon aggregates when measured using the Brunauer-Emmett-Teller (BET) method with nitrogen as the adsorbate (such as the “BET method using nitrogen”, or the “nitrogen BET method”) or the Density Functional Theory (DFT) method, can be from 50 to 300 m2/g, or from 100 to 300 m2/g, or from 50 to 200 m2/g, or from 50 to 150 m2/g, or from 60 to 110 m2/g, or from 50 to 100 m2/g, or from 70 to 100 m2/g.
  • a carbon aggregate containing MWSFs or connected MWSFs, as defined above, can have high specific surface area.
  • the carbon aggregate can have a BET specific surface area from 10 to 300 m2/g, or from 10 to 200 m2/g, or from 10 to 100 m2/g, or from 10 to 50 m2/g, or from 50 to 500 m2/g, or from 100 to 200 m2/g, or from 100 to 300 m2/g, or from 100 to 1000 m2/g.
  • the density of the carbon aggregates as-synthesized can be less than 0.1 g/cm3, or less than 0.5 g/cm3, or less than 0.25 g/cm3, or less than 0.2 g/cm3, or less than 0.1 g/cm3, or less than 0.05 g/cm3, or from 0.01 g/cm3 to 1 g/cm3, or from 0.01 g/cm3 to 0.5 g/cm3, or from 0.01 g/cm3 to 0.25 g/cm3, or from 0.01 g/cm3 to 0.2 g/cm3, or from 0.01 g/cm3 to 0.1 g/cm3, or from 0.01 g/cm3 to 0.075 g/cm3, or from 0.01 g/cm3 to 0.05 g/cm3.
  • the carbon aggregates when compressed (such as into a disk, pellet, etc.), and optionally annealed, have an electrical conductivity greater than 500 S/m, or greater than 1000 S/m, or greater than 2000 S/m, or from 500 S/m to 20,000 S/m, or from 500 S/m to 10,000 S/m, or from 500 S/m to 5000 S/m, or from 500 S/m to 4000 S/m, or from 500 S/m to 3000 S/m, or from 2000 S/m to 5000 S/m, or from 2000 S/m to 4000 S/m, or from 1000 S/m to 5000 S/m, or from 1000 S/m to 3000 S/m.
  • the density after compression is approximately 1 g/cm3, or approximately 1.2 g/cm3, or approximately 1.5 g/cm3, or approximately 2 g/cm3, or approximately 2.2 g/cm3, or approximately 2.5 g/cm3, or approximately 3 g/cm3.
  • compression pressure 2000 psi to 12000 psi are used, and the compressed material can be annealed at temperatures from 500°C and 1500°C, or from 800°C to 1000°C.
  • a carbon aggregate containing MWSFs or connected MWSFs, as defined above, has high electrical conductivity.
  • a carbon aggregate containing MWSFs or connected MWSFs, as defined above is compressed into a pellet and the pellet has electrical conductivity greater than 500 S/m, or greater than 1000 S/m, or greater than 2000 S/m, or greater than 3000 S/m, or greater than 4000 S/m, or greater than 5000 S/m, or greater than 10000 S/m, or greater than 20000 S/m, or greater than 30000 S/m, or greater than 40000 S/m, or greater than 50000 S/m, or greater than 60000 S/m, or greater than 70000 S/m, or from 500 S/m to 100000 S/m, or from 500 S/m to 1000 S/m, or from 500 S/m to 10000 S/m, or from 500 S/m to 20000 S/m, or from 500 S/m to 100000 S/m, or from 1000 S/m to 10000 S/m, or from from
  • the carbon nanoparticles and aggregates described herein are characterized by Raman spectroscopy to determine the species of carbon allotropes present, and their degree of order.
  • the main peaks in the Raman spectra for graphite and graphene are the G-mode, the D-mode, and the 2D-mode.
  • the G-mode peak has a wave number of approximately 1580 cm-1 and is attributed to the vibration of carbon atoms in sp2-hybridized carbon networks.
  • the D-mode peak has a wave number of approximately 1350 cm-1 and can be related to the breathing of hexagonal carbon rings with defects.
  • the 2D-mode peak is a second-order overtone of the D-mode and has a wave number of approximately 2690 cm-1.
  • the graphite- and graphene-containing carbon materials have a Raman spectrum (using 532 nm incident light) with a 2D-mode peak and a G-mode peak, and the 2D/G intensity ratio is greater than 0.2, or greater than 0.5, or greater than 1.
  • Raman spectroscopy can also be used to characterize the structure of MWSFs.
  • the Raman G-mode is typically at 1582 cm-1 for planar graphite but can be downshifted for MWSFs (such as to 1565-1580 cm-1).
  • the D-mode is observed at approximately 1350 cm-1 in the Raman spectra of MWSFs.
  • the ratio of the intensities of the D-mode peak to G-mode peak (such as the D/G intensity ratio) is related to the degree of order of the MWSFs, where a lower D/G intensity ratio indicates higher degree of order.
  • a D/G intensity ratio near or below 1 indicates a relatively high degree of order, and a D/G intensity ratio greater than or equal to 1.2 indicates lower degree of order.
  • a carbon nanoparticle or a carbon aggregate containing MWSFs or connected MWSFs, as described herein, has a Raman spectrum with a first Raman peak at about 1350 cm-1 and a second Raman peak at about 1580 cm-1, when using 532 nm incident light.
  • the carbon materials containing the MWSFs can have a Raman spectrum (using 532 nm incident light) with a D- mode peak and a G-mode peak, and the D/G intensity ratio is from 0.9 to 1.1, or less than about 1.2.
  • Hydrogen gas and carbon particles exiting the one or more reactors 110 are next cooled using an effluent cooler (heat exchanger) 120, in preparation for the gas-solids separation.
  • the cooled hydrogen gas and carbon particles enter a first cyclone separator 121 A, and then a second cyclone separator 121B.
  • the hydrogen gas and carbon particles that have not been filtered out by the cyclone separators are further filtered by the back-pulse filter system 123.
  • the back-pulse filter system 123 is also fed by a back- pulse gas line 160 to enable the cleaning of the filter elements within the back-pulse filter system 123.
  • the carbon particles filtered by the cyclone separators 121 A and 121B and filter system 123 are transported to a supersack for storage at arrow 127.
  • the hydrogen with the carbon particles filtered out is then further cooled in the dry cooler 125.
  • the hydrogen gas is stored in the H2 accumulator 126 to accommodate any flow difference between the hydrogen gas flow exiting the dry cooler 125 and entering the subsequent system components, and then compressed in the H2 compressor 128, before being purified in the pressure swing absorber (PSA) 130.
  • the purified hydrogen gas is sent to the H2 storage system 131, and the unpurified hydrogen that was rejected by the PSA 130 is sent to the flare 140 to be burned off.
  • the example system shown in Figure 2A also includes a hydrogen recycling line 150.
  • a hydrogen stream from the PSA 130 is routed back to the input of the compressor 104.
  • the gas line 160 that supplies the back-pulse gas for cleaning the filter elements in the back-pulse filter system 123 is also provided from a hydrogen stream from the PSA 130.
  • Gases that are produced as separated components in the microwave chemical processing system can be recycled.
  • purified and/or unpurified hydrogen can be recycled from one location in the microwave chemical processing system to another location in the system.
  • the purified hydrogen from the PSA and/or unpurified hydrogen rejected by the PSA can be routed back to the microwave plasma reactor.
  • the purified and/or unpurified hydrogen can be provided directly to the microwave plasma reactor, or it can be pre-treated (such as by a compressor, drier, or a purification system) before being provided to the microwave plasma reactor.
  • the purified hydrogen from the PSA and/or unpurified hydrogen rejected by the PSA can be routed back to the back-pulse filter to serve as the back-pulse gas.
  • the example system 200 shown in Figure 2A has particular components chosen to facilitate the conversion of compressed NG into hydrogen gas and carbon particles.
  • Systems for converting hydrocarbons (such as NG) into hydrogen and carbon particles may have additional components or may omit one or more of the components shown in the system in Figure 2A. Where there are different input materials and/or separated components, the systems can have different components.
  • the biogas in microwave chemical processing systems for the conversion of biogas into hydrogen gas and carbon particles, the biogas can be pre-treated before being converted into hydrogen gas and carbon particles in the microwave plasma reactors.
  • compositions and purities of biogas and in some cases water, carbon dioxide, hydrogen sulfide and/or other components of the biogas can be removed prior to conversion in the microwave plasma reactors.
  • Several of the elements in the microwave chemical processing systems are described in greater detail below.
  • Disclosed multi-stage gas-solid separation systems can contain multiple stages, where the first stage is designed to filter out the largest particles, and each subsequent stage is designed to filter out smaller particles than the preceding stage, such that the last stage is designed to filter out the smallest particles.
  • the particle sizes filtered by each stage can have various size ranges.
  • greater than 30%, or greater than 40%, or greater than 50%, or greater than 60%, or greater than 70%, or greater than 80%, or greater than 90%, or greater than 95%, or greater than 99%, of the carbon particles are filtered after the separated components are filtered by the first cyclone separator.
  • greater than 30%, or greater than 40%, or greater than 50%, or greater than 60%, or greater than 70%, or greater than 80%, or greater than 90%, or greater than 95%, or greater than 99% of the carbon particles are filtered after the separated components are filtered by the first cyclone separator and the second cyclone separator.
  • the concentration by mass of adsorbed hydrocarbons can be from 1% to 20%, or from 1% to 10%, or from 1% to 5%, or from 0.1% to 20%, or from 0.1% to 10%, or from 0.1% to 5%, or from 0.1% to 1%, or from 0.01% to 20%, or from 0.01% to 10%, or from 0.01% to 5%, or from 0.01% to 1%, or from 0.01% to 0.1%.
  • the cyclone separators have a cylindrical and/or conical interior, an input, and an output.
  • the input of the cyclone separators can be configured to receive a gas that contains a first particle concentration.
  • the cylindrical and/or conical interior contains a rotating flow of gas and particles (such as a vortex) and uses rotational effects (such as vortex separation) to separate the particles from the gas.
  • the output of the cyclone separators can be configured to expel a gas that contains a second particle concentration. Since some fraction of the particles are filtered by the cyclone separator, the second particle concentration is less than the first particle concentration.
  • the cyclone separators additionally contain a solids collection port, through which the particles that are filtered by the cyclone separator can be removed.
  • the solids collection port is connected to a load lock system, such that the particles that are filtered by the cyclone separator can be removed without exposing the interior of the cyclone separator to air.
  • the solids collection ports of the cyclone separators are connected to a jacketed (such as cooled, or heated) hopper to store the collected particles.
  • Solids collection ports of the cyclone separators are connected to a jacketed hopper, which is in turn connected to an additional particle storage unit (such as a vessel, a sack, a bag, or a supersack), which is used to store the collected particles and/or prepare for shipping.
  • a mechanical system (such as conveyor, belt, auger, screw type of system, or piston push rod) is included in the cyclone separators to transport the filtered particles from the internal environment to the output, to aid in particle collection.
  • the length (such as the dimension approximately aligned with the axis of the vortex) of the interior of the cyclone separator is from 0.1 m to 10 m, or from 0.1 m to 5 m, or from 0.1 m to 2 m, or from 0.1 m to 1 m, or from 0.1 m to 0.5 m, or from 0.5 m to 10 m, or from 0.5 m to 5 m, or from 0.5 m to 2 m, or from 0.5 m to 1.5 m, or greater than 0.1 m, or greater than 0.2 m, or greater than 0.5 m, or greater than 1 m, or greater than 1.5 m, or greater than 2 m, or greater than 5 m.
  • the cyclone separators described herein enable a high fraction of microwave plasma produced particles to be collected (such as greater than 90%), even though the particles are small (such as median size less than 10 microns) and have low densities (such as less than 0.2 g/cm3). Furthermore, the cyclone separators can operate at high gas flows (such as greater than 5 slm) and maintain high collection efficiencies (such as greater than 90%). The cyclone separators can also be integrated in-line with microwave plasma reactors without disturbing the environment within the reactor (such as the gas flows and oxygen levels). Additionally, the cyclone separators are compatible with hot separated components output from the reactors.
  • the back-pulse filters additionally contain a solids collection port, through which the particles that are filtered by the back-pulse filter can be removed.
  • the solids collection port is connected to a load lock system, such that the particles that are filtered by the back-pulse filter can be removed without exposing the interior of the back-pulse filter to air.
  • the solids collection ports of the back-pulse filter are connected to a jacketed (such as cooled, or heated) hopper to store the collected particles.
  • Solids collection ports of the back- pulse filter are connected to a jacketed hopper, which is in turn connected to an additional particle storage unit (such as a vessel, a sack, a bag, or a supersack), which is used to store the collected particles and/or prepare for shipping.
  • a mechanical system (such as conveyor, belt, auger, screw type of system, or piston push rod) is included in the back-pulse filter to transport the filtered particles from the internal environment to the output, to aid in particle collection.
  • the back-pulse filter system can contain one or more back-pulse filters, and a valve system for directing flow through the one or more back-pulse filters in forward or reverse directions.
  • Each back-pulse filter in the system can be in a filtering state or a cleaning state.
  • the gas and particle mixture is flowing through filter elements inside the back-pulse filters in a forward direction (such as from the upstream to the downstream side of the filter element).
  • the filter elements can be porous, such as sintered particles, a screen or mesh, and the particles can be filtered out of the mixture and be captured in the pores of the filter elements.
  • the particles that are captured in the pores of the filter elements inside of the back-pulse filters can be dislodged by directing gas flow through the filter elements in the reverse direction (such as from the downstream to the upstream side of the filter element).
  • a plurality of back-pulse filters is arranged in parallel such that a first back- pulse filter of the plurality of back-pulse filters can be in the cleaning state while other back- pulse filters of the plurality of back-pulse filters are in the filtering state.
  • This enables the overall back-pulse filter system to continuously filter particles from the microwave plasma reactor, without having to stop particle production to clean the filters.
  • the number of back- pulse filters arranged in parallel can be from, for example, 2 to 10, and the number of back- pulse filters in the filtering state and the cleaning state can change throughout a processing run.
  • the back-pulse filters in the gas-solids separation systems operate at pressures from 0.1 psig (pounds per square inch gauge) to 300 psig, or from 0.1 psig to 200 psig, or from 0.1 psig to 100 psig, or from 0.1 psig to 10 psig, or from 1 psig to 300 psig, or from 1 psig to 200 psig, or from 1 psig to 100 psig, or from 1 psig to 10 psig, or from 10 psig to 200 psig, or from 10 psig to 100 psig, or greater than 0.1 psig, or greater than 1 psig, or greater than 10 psig, or greater than 100 psig.
  • the back-pulse filter systems described herein enable a high fraction of microwave plasma produced particles to be collected (such as greater than 99%), even though the particles are small (such as median size less than 1 microns) and have low densities (such as less than 0.2 g/cm3). Furthermore, the back-pulse filter systems can operate at high gas flows (such as greater than 5 slm) and maintain high collection efficiencies (such as greater than 90%). The back-pulse filter systems can also be integrated in-line with microwave plasma reactors without disturbing the environment within the reactor (such as the gas flows and oxygen levels). Additionally, the back-pulse filter systems are compatible with hot separated components output from the reactors. The back-pulse filter systems described herein also enable truly interruption-free continuous operation by combining more than one back-pulse filters in parallel configured with a system of valves that allow some filters to be filtering while others are being cleared with back-pulses.
  • a cyclone separator 121 and a back-pulse filter system 123 are configured with hoppers in Figure 2B, for storing the carbon particles filtered by the cyclone separators and back-pulse filter systems.
  • Other components of the microwave chemical processing system that are integrated into the skids are not shown for simplicity.
  • FIG. 3C shows where there is one microwave energy generator 381 coupled to multiple FEWGs 382, and the reaction zones of the FEWGs are all connected together such that there is a single outlet 383 to collect the separated components.
  • an opening can have a substantially a half-sinusoidal shape having a substantially 1 :2 aspect ratio.
  • the wave has energy maxima at the midpoints of the waveguide throat, as shown.
  • the choice of dimensions, aspect ratios, and/or aspects of tuning the opening serve to flatten the e-field, which in turn serves to shape the plasma.
  • a tuned e-field shape can result in a wide plasma. The foregoing phenomena can be exploited regardless of the frequency of the microwave.
  • Figure 3L shows an illustrative numeric example.
  • the method 410 includes step 412 of providing an input material comprising a hydrocarbon gas; step 414 of processing the input material into separate components using a microwave plasma reactor, wherein the separated components contain hydrogen gas and carbon particles; and step 416 of filtering the carbon particles from the hydrogen gas using a multi-stage gas-solid separator system.
  • the multi-stage gas-solid separator system comprises: a first cyclone separator having an output; and a back-pulse filter system.
  • the first cyclone separator filters the carbon particles from the separated components; and the back-pulse filter system filters the carbon particles from the output from the first cyclone separator.
  • Example 1 Microwave Chemical Processing System Gas-Solid Separation System
  • a hydrocarbon was the input material for the reactor, and separated components were hydrogen gas and carbon particles containing graphite and graphene.
  • the carbon particles were separated from the hydrogen gas in a multi-stage gassolid separation system. After exiting the reactor, the hydrogen gas and carbon particles were processed through a cyclone separator first stage, and the output from the cyclone separator was then processed through a back-pulse filter second stage.
  • the particle size distribution of the carbon particles captured in the cyclone separator first stage in this example is shown in Figure 5C.
  • the mass basis cumulative particle size distribution 510 corresponds to the left y-axis in the graph (Q3(x) [%]).
  • the histogram of the mass particle size distribution 520 corresponds to the right axis in the graph (dQ3(x) [%]).
  • the median particle size captured in the cyclone separator in this example was approximately 33 pm, the 10th percentile particle size was approximately 9 pm, and the 90th percentile particle size was approximately 103 pm.
  • the mass density of the particles collected in the cyclone separator was approximately 10 g/L.
  • Figure 5 C also shows the results from a second experiment of this first
  • the particles produced in this example contained graphite, graphene, amorphous carbon, and no seed particles.
  • the particles in this example had a ratio of carbon to other elements (other than hydrogen) of approximately 99.5% or greater.
  • Figures 6A, 6B, and 6C show TEM images of as-synthesized carbon nanoparticles of this example showing the graphite, graphene, and amorphous carbon allotropes. The layers of graphene and other carbon materials can be clearly seen in the images.
  • the particle size distribution of the carbon particles captured in the cyclone separator first stage in this example is shown in Figure 6D.
  • the mass basis cumulative particle size distribution 610 corresponds to the left y-axis in the graph (Q3(x) [%]).
  • the histogram of the mass particle size distribution 620 corresponds to the right axis in the graph (dQ3(x) [%]).
  • the median particle size captured in the cyclone separator in this example was approximately 14 pm, the 10th percentile particle size was approximately 5 pm, and the 90th percentile particle size was approximately 28 pm.
  • the graph in Figure 6D also shows the number basis cumulative particle size distribution 630 corresponding to the left y-axis in the graph (Q0(x) [%]).

Abstract

La présente invention concerne un système réacteur qui comprend une source d'énergie micro-ondes qui génère une énergie micro-ondes et un guide d'ondes d'amplification de champ (FEWG) couplé à la source de micro-ondes. Le FEWG comprend une zone d'amplification de champ ayant une section transversale qui diminue sur une longueur du FEWG. La zone d'amplification de champ comprend une entrée de gaz d'alimentation qui reçoit un gaz d'alimentation, une zone de réaction qui génère un plasma en réponse à l'excitation du gaz d'alimentation par l'énergie micro-ondes, une entrée de traitement qui injecte une matière première dans la zone de réaction et une zone rétrécie qui retient une partie du plasma et combine le plasma et la matière première sous l'effet de l'énergie micro-ondes à l'intérieur de la zone de réaction. Une chambre de détente est en communication fluidique avec la zone rétrécie et facilite la détente du plasma. Une sortie délivre une pluralité de particules incluant du carbone issues du plasma détendu et de la matière première.
PCT/US2021/041110 2020-08-31 2021-07-09 Système réacteur à micro-ondes renfermant un plasma à auto-allumage WO2022046297A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001122690A (ja) * 1999-10-26 2001-05-08 Toyo Kohan Co Ltd マイクロ波プラズマｃｖｄ装置及びダイヤモンド薄膜を形成する方法
US20020050323A1 (en) * 2000-10-27 2002-05-02 Michel Moisan Device for the plasma treatment of gases
JP2004346385A (ja) * 2003-05-23 2004-12-09 Hamamatsu Kagaku Gijutsu Kenkyu Shinkokai マイクロ波プラズマ発生方法、マイクロ波プラズマ発生装置および前記装置を使用してダイヤモンド薄膜を製造する方法
US20140159572A1 (en) * 2011-04-28 2014-06-12 Gasplas As Method for processing a gas and a device for performing the method
US20180226229A1 (en) * 2017-02-09 2018-08-09 Lyten, Inc. Microwave Chemical Processing Reactor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001122690A (ja) * 1999-10-26 2001-05-08 Toyo Kohan Co Ltd マイクロ波プラズマｃｖｄ装置及びダイヤモンド薄膜を形成する方法
US20020050323A1 (en) * 2000-10-27 2002-05-02 Michel Moisan Device for the plasma treatment of gases
JP2004346385A (ja) * 2003-05-23 2004-12-09 Hamamatsu Kagaku Gijutsu Kenkyu Shinkokai マイクロ波プラズマ発生方法、マイクロ波プラズマ発生装置および前記装置を使用してダイヤモンド薄膜を製造する方法
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