TW201341609A - Methods and system for forming carbon nanotubes - Google Patents

Methods and system for forming carbon nanotubes Download PDF

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TW201341609A
TW201341609A TW101143104A TW101143104A TW201341609A TW 201341609 A TW201341609 A TW 201341609A TW 101143104 A TW101143104 A TW 101143104A TW 101143104 A TW101143104 A TW 101143104A TW 201341609 A TW201341609 A TW 201341609A
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stream
gas
system
reactor
configured
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TW101143104A
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Chinese (zh)
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Robert Dean Denton
Dallas Noyes
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Exxonmobil Upstream Res Co
Solid Carbon Prod Llc
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Publication of TW201341609A publication Critical patent/TW201341609A/en

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    • DTEXTILES; PAPER
    • D01NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01FCHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/127Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00Nanotechnology for materials or surface science, e.g. nanocomposites
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00Manufacture or treatment of nanostructures
    • CCHEMISTRY; METALLURGY
    • C01INORGANIC CHEMISTRY
    • C01BNON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00Carbon; Compounds thereof
    • C01B32/15Nano-sized carbon materials
    • C01B32/158Carbon nanotubes
    • C01B32/16Preparation
    • C01B32/164Preparation involving continuous processes
    • DTEXTILES; PAPER
    • D01NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01FCHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/127Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
    • D01F9/1271Alkanes or cycloalkanes
    • D01F9/1272Methane
    • DTEXTILES; PAPER
    • D01NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01FCHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/127Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
    • D01F9/1278Carbon monoxide
    • DTEXTILES; PAPER
    • D01NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01FCHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/127Carbon filaments; Apparatus specially adapted for the manufacture thereof by thermal decomposition of hydrocarbon gases or vapours or other carbon-containing compounds in the form of gas or vapour, e.g. carbon monoxide, alcohols
    • D01F9/133Apparatus therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01JCHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00002Chemical plants
    • B01J2219/00004Scale aspects
    • B01J2219/00006Large-scale industrial plants
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00Technologies relating to chemical industry
    • Y02P20/10General improvement of production processes causing greenhouse gases [GHG] emissions
    • Y02P20/12Energy input
    • Y02P20/129Energy recovery
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product
    • Y02P70/62Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear
    • Y02P70/621Production or treatment of artificial filaments or the like
    • Y02P70/623Energy efficient measures, e.g. motor control or heat recovery

Abstract

The present invention describes systems and methods for forming carbon nanotubes. One method involves forming a carbon nanotube using a feed gas in a first reactor. The carbon nanotubes are separated from the reactor effluent to form a waste stream. The feed gas, dry waste stream, or both are heated using waste heat from the waste stream. The waste stream is quenched in an ambient temperature heat exchanger to condense the water vapor to form a dry waste stream.

Description

Method and system for forming carbon nanotubes Related application

U.S. Patent Application Serial No. 13/263,311, entitled "Method for Producing Solid Carbon by Reducing Carbon Oxides", No. 10, 2011, which is incorporated herein by reference. In the case of the International Patent Application No. PCT/US2010/029934, entitled "Method for Producing Solid Carbon by Reducing Carbon Oxides", No. Priority, which was filed on April 5, 2010), which in turn advocates U.S. Provisional Patent Application No. 61/170,199 (issued April 17, 2009, entitled "Solution of Solid Carbon by Reduction of Carbon Oxide" The method of Producing Solid Carbon by Reducing Carbon Oxides, the disclosure of which is incorporated herein by reference.

This technology relates to industrial scale processes for forming carbon fiber and carbon nanomaterials.

This section is intended to introduce various embodiments of the present technology, which may be associated with example embodiments of the present technology. This discussion is generally believed to help provide a framework to facilitate a better understanding of the particular implementation of the technology. Therefore, it should be The explanation should be read from this point of view without necessarily having to be allowed by the prior art.

Materials that have been formed primarily from solid or elemental carbon have been used in many products for many years. For example, carbon black is a high carbon content material that is used as a reinforcing compound in pigments and in rubber and plastic products such as tires. Carbon black is often formed by incomplete pyrolysis of a hydrocarbon such as methane or a heavy aromatic oil. Thermal carbon black formed by pyrolysis of natural gas includes large non-agglomerated particles, such as particles having a size in the range of 200-500 nm. Furnace blacks formed by pyrolysis of heavy oils include particles that are much less cohesive or tacky, ranging from 10 to 100 nm, and the particles stick together to form a structure. In either case, the particles may be formed from a layer of graphene sheets having open ends or edges. Chemically, open edges form reactive regions that can be used to absorb, bind to substrates, and the like.

Recent renewed elemental carbon forms, such as fullerene, have been developed and are beginning to evolve in commercial applications. In contrast to the more open structure of carbon black, the Fuller system is formed from carbon in a closed graphene structure (i.e., where the edge bonds are bonded to other edges to form spheres, tubes, etc.). Two structures (carbon nanofibers and carbon nanotubes) have many potential applications, from batteries and electronic equipment to the use of concrete for the construction industry. The carbon nanomaterial may have a single layer of graphene or multiple nested walls of graphene, or form a fiber structure in the form of a cup or plate from a stacked sheet group. The end of the carbon nanotube tube often covers a hemispherical structure and has a Fuller-like structure. Unlike carbon black, a large-scale manufacturing method of carbon nanomaterials has not yet been realized. However, research has been conducted on many of the proposed manufacturing methods.

Arc-based, laser-based ablation technology and chemical gas Phase deposition is typically used to produce carbon nanotubes from carbon surfaces. For example, in Karthikeyan et al., "Large Scale Synthesis of Carbon Nanotubes" (E-Journal of Chemistry, 2009, 6(1), 1-12), it is used to produce carbon nanotubes. The technology of the tube. In one of the techniques described, an arc is used in the presence of a metal catalyst to achieve a productivity of about 1 gram per minute when the graphite is vaporized from the electrode. Other techniques described use laser ablation in an inert gas stream to vaporize carbon from the target electrode. However, laser technology uses high purity graphite and high power lasers, but provides low carbon nanotube yields that make it impractical for large scale synthesis. The third technique described by these authors is based on chemical vapor deposition (CVD) in which hydrocarbons are thermally decomposed in the presence of a catalyst. In some studies, these techniques have achieved productivity of up to several kilograms per hour at 70% purity. However, none of the methods can be practically used for large-scale commercial production.

Hydrocarbon pyrolysis is used to make carbon black and various carbon nanotubes as well as fullerene products. There are various different methods of producing and obtaining different forms of solid carbon by pyrolysis of hydrocarbons by using temperature, pressure, and presence of a catalyst to dominate the solid carbon form formed. For example, Kauffman et al. (U.S. Patent 2,796,331) discloses a method for producing various forms of fibrous carbon from hydrocarbons using hydrogen sulfide as a catalyst in the presence of residual hydrogen, and for concentrating the fibrous carbons on a solid surface. The method above. Kauffman also advocates the use of coke oven gas as a source of hydrocarbons.

In other studies, the flame-based technology is described in Vander Wal, RL et al., "Flame Synthesis of Single-Walled Carbon Nanotubes and Nanofibers." (Microgravity Combustion and Chemically Reacting Systems, 7th International Symposium, August 2003, 73-76 (NASA Research Publication: NASA/CP-2003-212376/REV1)). This technique introduces a CO or CO/C 2 H 2 mixture with a catalyst into a flame to form a carbon nanotube. The authors noted that high efficiency can be achieved using flame based technology for the manufacture of carbon black. However, the authors note that scaling the scale of synthetic flames presents many challenges. Specifically, the total time for catalyst particle formation, carbon nanotube formation, and carbon nanotube growth is limited to about 100 ms.

International Patent Application Publication No. WO/2010/120581 to Noyes discloses a process for producing various forms of solid carbon products by reducing carbon oxides using a reducing agent in the presence of a catalyst. The carbon oxides are typically carbon monoxide or carbon dioxide. The reducing agent is usually a hydrocarbon gas or hydrogen. The morphology of the desired solid carbon product can be controlled by the particular catalyst, the reaction conditions, and the optional additives used in the reduction. The process is carried out at low pressure and a low temperature quenching procedure is used to remove water from the feed stream.

While the techniques described can be used to form carbon nanotubes, none of these methods suggest practical methods for mass or industrial scale manufacturing. Specifically, both the amount formed and the process efficiency are low.

The specific examples disclosed herein propose a system for making carbon nanotubes. The system includes a configuration configured to use waste from the exhaust stream The feed gas feed gas heater is thermally heated and a reactor configured to form a carbon nanotube from the feed gas. A separator is configured to separate the carbon nanotubes from the reactor effluent stream to form an exhaust stream. The system includes a water removal system having an ambient temperature heat exchanger and a separator configured to separate a quantity of water from the exhaust stream to form a dry exhaust stream.

Another specific example proposes a method for forming a carbon nanotube. The method includes forming a carbon nanotube using a feedstock feed gas in a first reactor and separating the carbon nanotubes from the reactor effluent to form a waste stream. The feed gas, dry exhaust stream, or both are heated using waste heat from the waste stream. The waste stream is quenched in an ambient temperature heat exchanger to condense water vapor to form a dry exhaust stream.

Another specific example proposes a reaction system for forming a carbon nanotube. The reaction system includes two or more reactors configured to form a carbon nanotube from a gas stream comprising methane and carbon dioxide. In the reaction system, the effluent from each reactor prior to the final reactor is used as a feed stream to the downstream reactor, and the effluent stream from the final reactor contains a spent stream of reactant waste. A separation system is located downstream of each reactor, wherein each separation system is configured to remove carbon nanotubes from the effluent from the reactor. A feed heater is located downstream of each separation system, wherein each feed heater includes a heat exchanger configured to heat the feed gas stream for subsequent reactors using waste heat from the effluent from the reactor, and wherein The feed heater downstream of the final reactor is configured to heat the gas stream for the first reactor. The ambient temperature heat exchanger is located downstream of each feed heater, wherein each ambient temperature is hot The exchanger is configured to remove water from the effluent to form a feed stream for subsequent reactors. The compressor is configured to increase the pressure of the spent stream that is depleted of the reactants. An ambient temperature heat exchanger located downstream of the compressor is configured to remove water from the waste stream from which the reactants are depleted. The gas fractionation system is configured to separate the waste stream from which the reactants are depleted into a methane-rich stream and a carbon dioxide-rich stream. The mixer is configured to blend the methane-rich stream or the carbon dioxide-rich stream to the initial feed stream.

In the following detailed description sections, specific specific examples of the present technology are described. However, to the specific embodiments of the present technology or the specific scope of the application described below, it is intended to be used as an example only and the description of the specific examples are provided. Therefore, the present invention is not limited to the specific embodiments described below, but includes all alternatives, modifications, and equivalents within the spirit and scope of the appended claims.

First, for ease of reference, the specific terms used in the present application and their meanings in the content are explained. To the extent that the terms used herein are not defined below, the broadest definition of the term is given to a person skilled in the art, as reflected in at least one printed publication and issued patent. In addition, the present technology is not limited by the terms of the following description, and all equivalents, synonymous, new developments, and terms or techniques for the same or similar purposes are considered to be within the scope of the claims.

The carbon fiber, the nanofiber, and the nanotube are isomorphs of carbon having a cylindrical nanostructure. Carbon nanofibers and nanotubes are a family of fullerite structures The Fowler structure family includes a spherical carbon sphere called the "Fullite Body". The wall of the carbon nanotube is formed from a carbon sheet having a graphene structure. As used herein, a nanotube can include a single layer of wall nanotubes of any length and a multilayer wall nanotube. It is to be understood that the term "carbon nanotubes" as used herein and in the scope of the patent application includes other fullerene bodies of carbon, such as carbon fibers, carbon nanofibers, and other carbon nanostructures.

"Compressor" is a device for compressing a working gas (including a gas-vapor mixture or exhaust gas) and includes a pump, a turbo compressor, a reciprocating compressor, a piston compressor, a rotary vane or a screw compressor, and Apparatus and combination for compressing working gases. In some embodiments, a particular type of compressor is preferred, such as a turbo compressor. Piston compressors may be used herein to include screw compressors, rotary vane compressors, and the like.

A "device" as used herein is a collection of physical equipment that processes or transports chemical or energy products. In the broadest sense, the term "device" applies to any equipment that can be used to generate energy or form a chemical product. Examples of facilities include polymerization equipment, carbon black equipment, natural gas processing equipment, and power generation equipment.

"Hydrocarbon" is an organic compound mainly comprising elemental hydrogen and carbon, but may also be present in a small amount of nitrogen, sulfur, oxygen, metals or any other element of any amount. As used herein, hydrocarbon generally refers to a component found in natural gas, oil, or chemical processing facilities.

As used herein, the term "natural gas" means a multicomponent gas obtained from a crude oil well or from a subterranean gas zone. The composition and pressure of natural gas can vary significantly. Usually the natural gas stream contains methane (CH 4) as a main component, i.e., the natural gas stream is more than 50 mole% methane. The natural gas stream may also contain ethane (C 2 H 6 ), high molecular weight hydrocarbons (eg, C 3 -C 20 hydrocarbons), one or more acid gases (eg, hydrogen sulfide), or any combination thereof. Natural gas may also contain minor amounts of contaminants such as water, nitrogen, iron sulfide, waxes, crude oil or any combination thereof. The natural gas stream can be substantially purified prior to use in the specific examples to remove compounds that may act as poisons.

"Low BTU natural gas" is a gas that includes a significant proportion of CO 2 when recovered from a gas storage layer. For example, low BTU natural gas may include 10 moles or more of CO 2 in addition to hydrocarbons and other components. In some cases, low BTU natural gas may mostly include CO 2 .

When "substantially" is used to mean the quantity or amount of material, or its particular characteristics, it refers to an amount sufficient to affect the material or feature that is intended to be provided. In some instances, the exact allowable degree of deviation depends on the specific content.

Overview

The specific examples described herein suggest systems and methods for producing carbon fibers, nanofibers, and nanotubes (CNTs) on a commercial scale using materials that can include near stoichiometric mixtures of carbon dioxide and methane. In some embodiments, the CH 4 of the feedstock is more, while in other embodiments, the feedstock has more CO 2 . The process is carried out under high temperature and pressure conditions using a Bosch reaction, as discussed in Figure 2. The method can be energy neutral to slightly endothermic. At least a portion of the heat from the reaction can be collected for heating the feed gas to provide a portion of the heat used by the process during continuous operation. Due to the use of the high pressure process, the ambient temperature heat exchanger is sufficient to remove water vapor from the product stream without the use of a cryocooler. After separating the product formed during the reaction from the water, any residual amount of the limited reagent is separated from the exhaust gas mixture using a gas fractionation system and the reagent is recycled to the process.

As used herein, ambient temperature heat exchangers can include water quenchers, air coolers, or any other cooling system that is in heat exchange with a source that is substantially ambient temperature. It can be appreciated that the ambient temperature is substantially the temperature of the outside air at the location of the facility, for example from about -40 ° C to about +40 ° C, depending on the location of the facility. In addition, different types of ambient temperature heat exchangers can be used depending on the current ambient temperature. For example, a facility that uses a water chiller during the summer may use an air cooler during the winter. It can be appreciated that a suitable type of ambient temperature heat exchanger can be used at any point of the ambient temperature heat exchanger described herein. The type of ambient temperature heat exchanger in the entire plant can vary depending on the amount of cooling required.

Specific examples described herein may use carbon oxides as the primary carbon source to produce industrial quantities of carbon products, particularly such as fullereere, carbon nanotubes, carbon nanofibers, carbon fiber graphite, carbon black, and graphene. The balance of possible products can be adjusted by the conditions used for the reaction, including catalyst composition, temperature, pressure, starting materials, and the like. In a reactor system, carbon oxides are catalytically converted to solid solid carbon and water. These carbon oxides are available from a variety of sources, including the atmosphere, combustion gases, process gases, well gases and other natural and industrial sources.

The process of the invention uses two starting materials: a carbon oxide such as carbon dioxide (CO 2 ); and a reducing agent such as methane (CH 4 ). The reducing agent may include other hydrocarbon gases, hydrogen (H 2 ), or a mixture thereof. Hydrocarbon gas can serve as both an additional carbon source and as a reducing agent for carbon oxides. Other gases, such as syngas, may be produced as intermediate compounds in the process or included in the feed, and may also be used as a reducing agent. Syngas includes carbon monoxide (CO) and hydrogen (H 2 ), thus comprising carbon oxides and reducing agents in a single mixture. Syngas can be used as all or part of the feed gas.

Carbon oxides (especially carbon dioxide) are abundant gases extracted from exhaust gases, low BTU wells, and from some process gases. Although carbon dioxide can also be extracted from air, other sources often have much higher concentrations and are a more economical source of carbon dioxide. In addition, carbon dioxide can be obtained as a by-product of power generation. The use of CO 2 from such sources can reduce carbon dioxide emissions by converting a portion of the CO 2 to a carbon product.

The methods described herein can incorporate power generation and industrial processes for sequestering carbon oxides to enable them to be converted to solid carbon products. For example, the carbon oxides in the combustion or process off-gas can be separated and concentrated to become the feedstock for the process. In some cases, such methods can be directly incorporated into the process without separation and concentration, for example as an intermediate step in a multi-stage gas turbine power plant.

1 is a block diagram of a reaction system 100 that produces a carbon structure, such as a by-product of a carbon dioxide sequestration reaction. Providing a feed gas to the reactor system 100, 102, 102 of the feed gas mixture of CO 2 and CH 4 of. In some instances, the reaction may be used to sequester the exhaust gas from power plants and other flow CO 2. In other instances, the higher concentration of CH 4 gas flow from the low BTU gas in the fields. The feed gas 102 may be present in other components, such as C 2 H 6, C 2 H 4 and the like. In one embodiment, the feed gas 102 can be treated to remove such components, for example, for sale as a product stream.

The feed gas 102 is heated by the heat exchanger 104 to carry out the reaction. During continuous operation, the heating is carried out using heat 106 collected from the reaction. During startup, an auxiliary heater is used to provide initial heat as described further below. The heated feed gas 108 is fed to the reactor 110.

In reactor 110, a catalyst reacts with a portion of the heated feed gas 108 to form carbon nanotubes 112. As described in more detail below, reactor 110 can be a fluidized bed of any of a variety of different catalysts including, for example, metal particles, supported catalysts, and the like. The carbon nanotubes 112 are separated from the flow stream 114 exiting the reactor 110, leaving an exhaust stream 116 containing excess reagent and water vapor. The heat from the flow stream 114 is used to form the heated feed gas 108 before the flow stream 114 enters the chiller as the exhaust stream 116.

The exhaust stream 116 passes through an ambient temperature heat exchanger, such as a water chiller 118, which condenses the effluent 120. The resulting dried exhaust stream 122 is used as a feed stream to the gas fractionation system 124. It will be appreciated that the dry exhaust stream as used herein has a large amount of removed water, but still has a small amount of water vapor. For example, the dry exhaust stream may have a dew point greater than about 10 ° C and greater than about 20 ° C or higher. The dryer can be used to reduce the dew point prior to gas fractionation, for example, to -50 ° C or lower.

The gas fractionation system 124 removes a portion of the lowest concentration reagent and recycles it to the process, for example by blending the recycle 126 with the feed gas 102. The higher concentration gas or excess feed 128 can be disposed of, for example, by a downstream user for sale. For example, if CO 2 is the highest concentration gas in the blend with CH 4 , the gas fractionation system 124 can be used to remove any CH 4 remaining in the exhaust stream and return it as recycle 126. . This method functions as a homogeneous reaction between the reagent and the solid carbon, as further discussed with reference to FIG.

2 is a balanced C-H-O equilibrium diagram 200 between carbon 202, hydrogen 204, and oxygen 206, showing species that are balanced under various temperature conditions. There are ranges of reactions involving these three elements, in which various different equilibriums have been referred to as reactions. The equalization line at different temperatures across the graph shows the approximate area that will form solid carbon. For each temperature, solid carbon will form in the region above the associated equalization line, but will not form in the region below the equalization line.

Hydrocarbon pyrolysis is an equilibrium reaction between hydrogen and carbon that facilitates solid carbon production, typically with little or no oxygen or water present, for example, along an equilibrium line 208 from a higher hydrogen 204 content to a higher carbon 202 content. The Boudouard reaction (also known as carbon monoxide disproportionation) is an equilibrium reaction between carbon and oxygen that facilitates solid carbon production, usually with little or no hydrogen or water present, for example, from a higher oxygen content of 206 to a higher carbon 202. The equilibrium line 210 of the content.

The Bosch reaction is an equilibrium reaction that favors the production of carbon, oxygen and hydrogen in solid carbon production. In the C-H-O equilibrium map 200, the Bosch reaction is located in a triangular inner region between the solid carbon and the reagents containing various combinations of carbon, hydrogen and oxygen. Many points in the Bosch reaction zone facilitate the formation of CNTs and other forms of several solid carbon products. The reaction rate and product can be enhanced by the use of a catalyst such as iron. The choice of catalyst, reaction gas, and reaction conditions provides control over the type of carbon formed. As such, these methods open up new ways to make solid carbon products such as CNTs.

Reaction system

3 is a simplified flow diagram of a reaction system 300 for producing a carbon product from a gas feed comprising carbon dioxide and methane. As shown, the higher the reaction system 300 may be used or the CO 2 content higher CH 4 content of the feed gas 302. More specifically, the reactor system of FIG. 4 lines for discussion higher the CO 2 content of the feed to those discussed higher CH 4 content of the feed gas by gas 5 and FIG. In reaction system 300, feed gas 302 is combined with a recycle gas 304 having a reduced concentration of less gas. This can be done using static mixer 306.

The combined gas stream 308 is passed through a heat exchanger or a series of series heat exchangers 310 to be heated by the reactor effluent stream. The temperature of the heated gas stream 312 can be raised from about 90 °F (about 32.2 °C) to about 1400 °F (about 760 °C). This temperature may be sufficient to maintain the reaction during continuous operation. All or part of this heat may be provided by the package heater 314 during startup. Hot gas stream 316 is then introduced to first fluidized bed reactor 318. A general fluidized bed reactor that can be used in a specific example is discussed with reference to FIG. In the first fluidized bed reactor 318, a carbon nanotube system is formed on the catalyst particles. These catalyst particles and reaction systems are discussed further with reference to FIG.

The carbon nanotubes are carried in a reactor effluent stream 320 from a first fluidized bed reactor 318. The reactor effluent stream 320 can be at a temperature of about 1650 °F (about 899 °C) and can be cooled to provide, for example, heat to heat some or all of the reactants. Prior to or after cooling, the reactor effluent stream 320 is passed through a separation device, such as a first locked feed leak. Bucket 322 to remove the carbon nanotubes. The resulting exhaust stream 324 is used to provide heat in the heat exchanger 326. The carbon may also be removed in a second separation unit (not shown) at a temperature below the exhaust stream 324. This is particularly easy to accomplish when multiple heat exchangers in parallel can be used to cool the exhaust stream 324 while heating the feed gas supplied to the next reactor 336. Typically, all of the carbon solids are removed by a separation device prior to condensing any water vapor present in the exhaust stream 324. The cooled exhaust stream 328 is then passed through an ambient temperature heat exchanger 330 that further cools the condensed exhaust stream 328 and forms a quantity of water that condenses into a liquid, which is then fed to the stream. The container 332 is separated. Water 334 is removed from the separation vessel and a reactant stream 336 of about 100 °F (about 38 °C) is discharged overhead of the first separation vessel 332.

Reaction stream 336 is passed through heat exchanger 326 and heated by waste heat from exhaust stream 324. The heated stream 338 is fed to a second fluidized bed reactor 340 where additional carbon nanotubes are formed. However, the heated stream 338 may not be at a sufficiently high temperature sufficient to form a carbon nanotube in the second fluidized bed reactor 340, such as greater than about 1600 °F (about 871 °C). To increase the temperature of the heated stream 338, a second package heater 341 can be used. In some embodiments, the second reactor effluent stream 342 is used to provide heat to the second reactant stream 336. The second reactor effluent stream 342 is then fed to a second locked feed funnel 344 to separate the carbon product from the second reactor effluent stream 342. When the resulting exhaust stream 346 passes through the heat exchanger 310, it is used to provide heat to the combined gas stream 308.

Although only two fluidized bed reactors 318 and 340 are shown, reaction system 300 may contain more reactors as desired. The number of reactors is determined by the amount of raw materials and the amount of each raw material desired. In some cases, three, four or more reactors may be used, wherein the effluent stream from each reactor provides heat to the feed gas of the next reactor in the sequence. Moreover, the reactors are not necessarily fluidized bed reactors, as other configurations may be used in specific examples. For example, a fixed bed reactor, a tubular reactor, a continuous feed reactor, or any of several other configurations can be used.

After providing heat to the combined gas stream 308, the cooled waste stream 348 passes through the ambient temperature heat exchanger 350 and is then fed to the separation vessel 352. Water 354 settles in the separation vessel 352 and is removed from the bottom. The resulting gas stream 356 is about 100 °F (about 38 °C) and has a pressure of about 540 psia (about 3,720 kPa). In one embodiment, the gas is then dried to a low dew point in a dryer (not shown). The stream enters a compressor 358 that increases the pressure of the gas stream 356 to about 1050 psia (about 7,240 kPa) to form a high pressure stream 360 that passes through another ambient temperature heat exchanger 362. If a dryer is not used, the high pressure stream 360 is fed from ambient temperature heat exchanger 362 to a separation vessel 364 for removing any remaining water.

The dried gas stream 366 is then sent to a gas fractionation system 368, from which the gas feed system 368 separates the feed 370. In a suitable excess of the reaction from CO 2 based system 300, 370 may overfeeding comprising predominantly CO 2, mainly recycled gas may comprise CH 4. In an appropriate excess of the reaction CH 4 based system 300, 370 may overfeeding comprising predominantly CO 2, mainly recycled gas may comprise CH 4. In some embodiments, excess feed 370, recycle gas 304, or a portion of both can be tapped to provide a fuel gas stream, a flush gas stream, or both for the apparatus.

The reaction conditions employed can result in significant degradation of the metal surface as indicated by the choice of the catalyst itself which can comprise degraded beads. Accordingly, the method is designed to reduce the amount of metal exposed to the process conditions and is further discussed with reference to the following figures.

4A, 4B and 4C are simplified flow diagrams of other reaction systems 400 for making carbon nanotubes from a gas feed comprising carbon dioxide and methane. In Fig. 4, similar digital items are as shown in Fig. 3. The method of numbered diamond process corresponding to the analog value, the higher the CO 2 content as provided in Table 1, the feed gas 402. The second set of simulated values is provided in Table 2. As shown in the second simulation, many of the results show that under some conditions, the overall process can be slightly endothermic. In this case, the additional heat provided by the second package heater 341 can be used to increase carbon nanotube production while reducing the production of other products, such as amorphous carbon. As for Figure 3, feed gas 402 is passed through static mixer 306 where it is combined with high methane recycle gas 404. The combined gas stream 308 passes through a heat exchanger 310, for example, including a multiple shell heat exchanger and a tube heat exchanger 406. The main difference between this detailed flow chart 4 and Figure 3 is the use of a heat exchanger to cool the reactor effluent streams 320 and 342 prior to separating the CNTs from the reactor effluent streams 320 and 342.

In this particular example, the heated gas stream 312 is flowing through the second heat. The exchanger was previously raised in heat exchanger 310 to a temperature of about 800 °F (about 427 °C). In the second heat exchanger 408, the heated gas stream 312 flows through the first ceramic soaking block heat exchanger 410 as indicated by arrow 412. The heat stored in the first ceramic soaking block heat exchanger 410 is exchanged with the heated gas stream 312 and the temperature can be raised to about 1540 °F (838 °C).

Although the first ceramic soaking block heat exchanger 410 is used to heat the heated gas stream 312, the second ceramic soaking block heater 414 is used to cool the second reactor effluent stream 342 by This flow proceeds through the second ceramic soaking block heater 414 as indicated by arrow 416. When the second ceramic soaking block heat exchanger 414 reaches a selected temperature, or the first ceramic soaking block heat exchanger 410 drops to a selected temperature, the position of the inlet valve 418 and the outlet valve 420 are varied. In other words, the valve that opens is closed and the valve that is closed is opened. Changing the position of the valves causes any of the ceramic soaking block heat exchangers 410 or 414 to be heated by the flow from the reactor 340 and to heat the heated gas stream 312 for ceramic heat block heat exchange. Which of the devices 414 or 410 changes. After flowing through the ceramic soaking block heat exchanger 410 or 414, the flow system can be as shown in FIG.

The second heat exchanger 326 can also include a shell and tube heat exchanger 422, in which case the shell and tube heat exchanger 422 will have a temperature of the second reactant stream 336 from point 11 of about 100 °F (about 37.8 °C). Increase to about 715 °F (about 379.4 ° C) to point 12. The second reactant stream 336 is then passed through another heat exchanger 424 that includes two ceramic soaking block heat exchangers 426. The ceramic soaking block heat exchangers 426 are configured to have The exchange stream is shown as the second heat exchanger 408 discussed above. Other portions of system 400 are similar to those described in Figure 3, except that process values may vary and the associated process values for the system are shown in Table 1 or Table 2 for other simulations. Furthermore, more than two reactor systems can be used in this specific example.

In this particular example, the CNT separation system 426 includes a cyclone separator 428, a locked addition funnel 430, and a filter 432. After most of the CNTs are deposited in the lock-up addition funnel 430 by the cyclone reactor 428, the remaining CNTs are separated from the exhaust streams 324 and 346 using a filter 432. This can help prevent clogging or other problems caused by residual CNTs in the exhaust streams 324 and 346. Filter 432 may especially include a bag filter. The CNT separation system 426 is discussed in more detail with reference to FIG.

After removal of the last of the high pressure water stream 360 from the third separation vessel 364, 366 to the gas flow fractionation system 434 via the drying gas, the gas fractionation system 434 can be isolated from the high methane recycle gas CO 2 waste stream 436 404. Gas fractionation system 434 is further discussed with reference to FIG. Individual streams 404 and 436 can be used to supply other gases of the process. For example, fuel gas stream 438 may be separated from high methane recycle gas 404 and used to power turbines, boilers, or other equipment to, for example, provide power to system 400. Moreover, CO 2 can be separated from the waste gas stream 436 440 flush. This flushing gas stream 440 can be used to cool and rinse the CNTs as described in FIG. The flushing gas can also be used as a variety of different cleaning functions in the apparatus, such as blowing residual CNTs out of the ceramic heat exchanger 410, 414 or 426 when the flow is reversed.

The process conditions shown in Tables 1 and 2 are intended only as examples of conditions that can be found in the device, such as those determined by simulation. The actual conditions can vary significantly and the conditions shown can be drastically changed. A similar equipment configuration can be used for high methane feed gas, as discussed in Figure 5. Additionally, the recycle and effluent waste streams can contain significant amounts of hydrogen and carbon monoxide, for example, greater than about 5 mole percent each, greater than about 10 mole percent each, or even greater than 20 mole percent each. These components are typically present in the feed and all non-CO 2 product streams (ie, recycled methane) always contain some CO and H 2 .

5A, 5B, and 5C are simplified flow diagrams of other reaction systems 500 for making carbon nanotubes from a gas feed comprising carbon dioxide and methane. In Fig. 5, similar digital items are as shown in Figs. 3 and 4. In addition, some numbers are not shown to simplify the figure. In this particular example, the feed gas may have a higher methane content than carbon dioxide, such as about 80 mole % CH 4 and 20 mole % CO 2 , although any ratio may be used. Similarly, the recirculation gas to the CO 2 content of greater than 504 CH 4 content of the feed gas can be formed from about 51 mole% CO 2 and 49 mole% CH 4 of the reactor. The remainder of the method is similar to the system 400 discussed in FIG. However, since the waste stream 506 CH 4 energy sold to the market, it can be configured by using the counter to produce a higher purity CH 4 (e.g. about 99 mole% CH 4 or more persons) of the gas fractionation system 508. A gas fractionation system 508 that can be used is further discussed with reference to FIG. For system 400 discussed with respect to FIG. 4, flush gas stream 510 can be taken from recycle gas 504 and fuel gas stream 512 can be taken from CH 4 waste stream 506. It will be appreciated that the waste stream is only for this method. The CH 4 waste stream 506 of Figure 5 and the CO 2 waste stream 436 of Figure 4 can be sold to, for example, a pipeline operator.

It will be appreciated that the system for forming a carbon nanotube can include any number of reactors, any number of types, including the illustrated fluidized bed reactor. In one embodiment, only a single reactor is used to form the carbon nanotubes.

Reactor system

FIG. 6 is a diagram of a fluidized bed reactor 600 for forming a carbon nanotube 602. Hot gas feed stream 604 is fed through line 606 to the bottom of fluidized bed reactor 600. Control valve 608 can be used to regulate the flow of hot gas feed stream 604 into the reactor. The hot gas feed stream 604 flows through the distributor plate 610 and fluidizes the catalyst beads 612 in place by the reactor wall 614. As used herein, "fluidization" means that the catalyst beads 612 flow around each other to pass the bubbles, providing a flow of fluid. As discussed herein, the reaction conditions are very severe for any exposed metal surface because the metal surface will act as a catalyst for the reaction. Therefore, the reaction will cause the exposed metal surface to slowly degrade. Thus, the inner surface of the reactor (including reactor wall 614 and head end 615) and distributor plate 610 and other components can be made of a ceramic material to protect the surfaces.

When hot gas feed stream 604 flows through the fluidized bed of catalyst particles 612, CNTs 602 will be formed from catalyst beads 612. The flowing hot gas feed stream 604 carries the CNTs 602 to the overhead line 616 where the CNTs 602 are removed from the reactor 600. Depending on the flow rate, such as control valve 608 adjustment, some amount of catalyst beads 612 or particles fragmented from the contact beads 612 may be transported to the top line 616. Thus, the catalyst separator 618 can be used to separate the catalyst beads and larger particles from the reactor effluent stream 620 and return it to the reactor 600 via the recycle line 622. Any number of configurations can be used for the catalytic separator 618, including cyclones, settling tanks, addition funnels, and the like. The reactions occurring in a fluidized bed are discussed in more detail in Figure 7.

FIG. 7 is a schematic illustration of a catalytic reaction 700 for forming a carbon nanotube on a catalyst bead 702. The hot gas feed stream 706 in the initial reaction between a portion of the CH 4 and CO 2 704 results in the formation of a stoichiometric amount of CO and H 2. Excess source gas 706 is continuously passed through the reactor, which aids in fluidizing the bed and entraining CNT 708 and catalyst particles 710.

The reaction to form CNTs 708 occurs on the catalyst beads 702. The size of the CNT 708 and the type of CNT 708 (e.g., single layer or multi-wall CNT 708) may be controlled by the size of the particles 712. In other words, a core of iron atoms having a sufficient size at the boundary of the particles forms a nucleation site where the carbon product grows on the catalyst beads 702. Generally, smaller particles 712 will form fewer layers in CNT 708 and can be used to obtain single layer wall CNTs 708. Other parameters can also be used to influence the morphology of the final product, including reaction temperature, pressure, and feed gas flow rate.

CO and H 2 in the grain boundaries 714 of the reaction, the active catalyst particles are lifted from the catalyst beads 716 702, and forms H 2 O 718 708 and the CNT of solid carbon. The CNTs 708 are broken from the catalyst beads 702 and from the catalytic particles 710. The larger catalyst particles 710 can be captured and returned to the reactor, for example, by the catalyst separator 618 discussed with reference to Figure 6, while very fine catalyst particles 710 will be carried with the CNTs 708. The final product will comprise about 95 mole percent solid carbon and about 5 mole percent metal, such as iron. CNTs 708 are often coagulated to form clusters 720, which are a common form of final product. Portion of the CO and H 2 and passed through the reactor without the reactor effluent stream contaminant of the reactor.

As the reaction proceeds, the catalyst beads 702 degrade and eventually become consumed. Therefore, the reaction can be described in a metal dusting reaction. In some embodiments, the metal surface is protected from attack by a ceramic lining because the metal surface in contact with the reaction conditions not only degrades, but also forms a product of suitable quality.

Catalyst beads 702 can comprise any number of other metals, such as nickel, ruthenium, cobalt, rhodium, and other metals. However, the catalytic position on the catalyst beads 702 is in principle composed of iron atoms. In one embodiment, the catalyst beads 702 comprise metal particles, such as beads of about 25 to 50 mesh that can be used for spraying. In one embodiment, the catalyst can be a stainless steel ball bearing or the like.

Gas fractionation system

Figure 8 is a simplified flow diagram of a gas manufacturing process 800 that can be used in a reactor system for making carbon nanotubes. Gas fractionation system 800, such as may be used in a high overall CO 2 fractional distillation reactor system of FIG. 4 discussed. In gas fractionation system 800, feed gas 802 is fed to dryer 804 to reduce the dew point to about -70 °F (about -56.7 °C) or less. Feed gas 802 may correspond to dried gas stream 366 as discussed in Figures 3-5. Dryer 804 can be a fixed or fluidized drying machine tool that contains an adsorbent such as molecular sieves, desiccants, and the like. Other dryer technologies, such as a low temperature dryer system, can also be used. In some embodiments, the dryer can be located prior to compressor 358, which eliminates the need for ambient temperature heat exchanger 362.

Dry gas feed 806 is then fed to low temperature chiller 808 to lower the temperature to prepare for separation. Since CO 2 at -77 deg.] F (about -61 deg.] C) will condense out of the gas, a multi-stage quench system 810 may be used to level the temperature is reduced to about. The multi-stage quench system 810 can include a heat collection system 812 to heat the outlet gas using energy 813 from the dry feed gas 806.

The quench feed 816 is fed to a separation vessel 818 to separate the liquid stream 820 and the vapor stream 822. Vapor stream 822 is passed through expander 824 to reduce temperature by creating mechanical work during adiabatic expansion. In one embodiment, mechanical work 826 is used to drive a generator 828 that provides a portion of the power used in the device. In other embodiments, mechanical work 826 is used to drive a compressor, such as a refrigerant stream for compressing a multi-stage quench system 810. This expansion can form a two-phase stream 830.

The liquid stream 820 and the two phase stream 830 are fed to a separation column 832, such as at a different feed along the separation column 832. Heat is supplied to the separation column 832 by the reboiler 834. The reboiler 832 is heated by the flow from the heat exchanger 836. Heat exchanger 836 can be part of a chiller system that is warmer than separation column 832, but below ambient temperature. The bottom stream 838 is reinjected through the reboiler 834 and after the warming portion 840. Outlet stream 842 from the reboiler 834 of the product 844 provides CO 2. A portion 846 of the CO 2 product 844 can be recycled through the heat exchanger 836 to bring energy to the reboiler 834.

The overhead stream 848 from separation column 832 is a methane-rich stream comprising, for example, about 73 mole % CH 4 and about 23 mole % CO 2 . As before, the overhead stream 848 can be used in the chiller system 812 to cool the dry gas feed 806 and the overhead stream 848 to warm to form the recycle gas 850. Other components that may be present in the recycle gas 850 include, for example, about 3.5 mole % CO and H 2 . If methane is to be used for sale, such as in the high methane reaction system discussed with reference to Figure 6, a higher purity separation system can be used, as discussed in Figure 9.

9 is a simplified flow diagram of another gas production process 900 that can be used in a reactor system for making carbon nanotubes. In Figure 9, similar numbered items are discussed in Figure 8. In the gas fractionation process 900, it may be quenched directly fed 816 fed to the first separation column 902, the first separation column 902 is separated CO 2. The CO 2 is discharged from the first separation column 902 in the bottoms product stream 904. A portion of the bottoms product stream 904 is passed through a reboiler 906 which adds heat. The heated stream 908 is then reinjected into the first separation column 902. The residual bottoms stream 904 CO 2 product 910 is formed, which is recycled, for example as discussed with reference to FIG recycle gas 504.

The overhead stream 912 from the first separation column 902 is sent to a second separation column 914 to further purify the methane product. The bottoms product stream 916 from the second separation column 914 is pressurized by pump 918 and returned to the first separation column 902 as reflux stream 920. The overhead stream 922 from the second separation column 914 is passed through a chiller 924 that can use the nitrogen refrigeration unit 926 to achieve a much lower temperature. The quench stream is then aspirated to a separation vessel 928. The overhead stream from the separation vessel 928 930 CH 4 of the enriched product. The overhead stream 930 can be used to provide cooling of the dry gas feed 806, such as by feeding through a shared quench system 812. The bottoms product stream 934 from the separation vessel 928 is pressurized by a pump 936 and returned to the second separation column 914 as a reflux stream 938.

The configurations and units discussed with reference to Figures 8 and 9 are merely examples. Any number of changes can be made to these systems. In addition, other gas separation systems can be used in the specific examples as long as the flow rate and purity level can be obtained.

Separation system

Figure 10 is a simplified flow diagram of a separation system 1000 in which a reactor effluent stream separates carbon nanotubes. The separation system 1000 overlaps the lock-type addition funnel 430 shown in Figures 4 and 5 and is used to separate CNTs from the program for packaging. Each reactor in the system can have separate package columns 1002 and 1004. Since different reactors can produce different amounts of CNTs, the equipment can be sized differently, but the functions can be the same. For example, in the first simulation, the amount of CNTs separated by the first package column 1002 can be about 162.7 tons per day (148,000 kilograms per day), while the amount removed to the second package column 1004 can be about 57.5 tons per volume. Day (52,000 kg / day).

Each package column 1002 and 1004 can have a sampling valve 1006 to remove CNTs from the locking addition funnel 430. Valve 1006 can be a rotary valve configured to enable passage of a particular amount of CNTs and gases during a portion of the rotational return point. In some embodiments, the sampling valve 1006 can be configured to complete Fully open the ball valve for a selected period of time to allow a selected amount of CNTs and gas to pass before being fully closed. The CNTs and gases are flowed into the barrel 1008 for rinsing and cooling.

After sampling valve 1006 is closed, you can open into the flushing stream 1010 to 1008 clear the tub residual gas, such as CO, H 2, H 2 O and CH 4. As noted above, the flushing stream 1010 can be taken from the CO 2 rich side of the gas fractionation system, such as the flushing gas stream 440 discussed with reference to FIG. 4, or the flushing gas stream 510 discussed with reference to FIG. The rinse outlet stream 1012 will carry some amount of CNTs and other fine particles and may pass through the filter 1014 before being returned to the process as a rinse feed 1016. The filter 1014 can be a bag filter, a cyclone or any suitable separation system. After the flushing is complete, the encapsulation valve 1018 will open to allow the CNT stream 1020 to flow to the fill station 1022 for packaging into a bucket or canister for sale.

The above separation system is only an example. Any number of other systems can be used in a specific example. However, such CNTs have a very low density, below about 0.5 g/cc, depending on the morphology distribution, and optimally can be packaged in a system configured to separate them from the atmosphere to reduce The amount lost to the equipment environment.

method

11 is a method 1100 for producing a carbon nanotube from a feed gas comprising methane and carbon dioxide. Method 1100 begins at block 1102 where a mixed CO 2 /CH 4 feedstock is obtained. This material can be obtained from any number of sources. As noted above, the feedstock may include natural gas recovered from an underground gas storage layer, waste gas from a power plant, or any number of gases from natural or plant sources.

At block 1104, the feedstock is combined with the recycle gas obtained from the offgas produced in the process. As described herein, the recycle gas can be obtained from the offgas by cryogenic gas fractionation and any number of other techniques. At block 1106, the combined gas stream is heated using waste heat collected from the reaction sequence. After heating, at block 1108, the combined gas stream is reacted with a metal catalyst in a reactor to form CNTs. At block 1110, the CNTs are separated from the exhaust. At block 1112, the separated CNTs are rinsed and packaged for delivery to the market.

The exhaust gas is cooled to remove excess water formed during the reaction. Since the process is carried out at high temperatures and pressures, the ambient temperature heat exchanger provides sufficient cooling to condense water vapor. The procedures described in blocks 1106 through 1114 will be repeated for each of the sequential reactors in the reaction system.

At block 1116, the offgas is fractionated into a CO 2 rich stream and a CH 4 rich stream. At block 1118, any stream containing excess reagents may be sold while another stream may be recycled to block 1104 for use in the process.

Other specific examples of the subject matter of the claim may include any combination of the elements listed in the following numbered paragraphs:

CLAIMS 1. A system for making a carbon nanotube comprising: a feed gas heater configured to heat a feed gas using waste heat from an exhaust stream; a reactor configured to receive from the feed The gas forms a carbon nanotube; a separator configured to separate the effluent stream from the reactor A carbon nanotube tube forms an exhaust stream; and a water removal system comprising an ambient temperature heat exchanger and a separator configured to separate a quantity of water from the exhaust stream to form a dry exhaust stream.

2. The system of paragraph 1, wherein the ambient temperature heat exchanger comprises a water chiller.

3. The system of paragraph 1 or 2, wherein the ambient temperature heat exchanger comprises an air cooled heat exchanger.

4. The system of paragraph 1, 2 or 3, comprising a package heater configured to heat a feed gas for initial startup of the system.

5. The system of any of the preceding paragraphs, comprising: a heat exchanger configured to heat the dry exhaust stream to form a second feed gas using waste heat from the exhaust stream; a second reactor Constructed to form a carbon nanotube from the second feed gas; a separator configured to separate the carbon nanotubes from the effluent stream from the second reactor to form a second exhaust stream, and Wherein the exhaust stream for the feed gas heater includes the second exhaust stream; and a water removal system configured to quench the second exhaust stream and remove a large amount of water using an ambient temperature heat exchanger The second exhaust stream separates water to form a second dry exhaust stream.

6. The system of paragraph 5, comprising a compressor configured to increase a pressure of the second dry exhaust stream; and a final water removal system configured to be removed from the second exhaust stream water.

7. The system of paragraph 5 or 6, which comprises a counter configured to separate via the second exhaust gas stream from the methane-enriched gas stream and the rich stream of the fractionation system 2 CO.

8. The system of paragraphs 5, 6 or 7, comprising a mixing system configured to mix the methane-rich stream into the feed gas prior to the feed gas heater.

9. The system of any one of claims 5 to 8, wherein the gas fractionation system comprises a low temperature condensation configured to separate a gas condensable at a temperature from a gas that does not condense at the temperature. system.

10. The system of paragraph 1 or 5, wherein the reactor is a fluidized bed reactor that fluidizes the catalyst using a reverse flow of feed gas.

11. The system of paragraph 10, wherein the catalyst comprises metal spray beads.

12. The system of paragraph 10 or 11, wherein the catalyst comprises metal beads comprising iron and nickel, chromium or any combination thereof.

13. The system of paragraph 10, 11 or 12, wherein the catalyst comprises metal beads having a size between about 25 mesh and 50 mesh.

The system of any of the preceding paragraphs, wherein the reactor is lined with a material configured to prevent degradation of the metal shell.

The system of any of the preceding paragraphs, wherein the pipe connection between the reactor and the cross heat exchanger is lined with a refractory material configured to protect the metal surface from degradation.

16. The system of any of the preceding paragraphs wherein the feed gas heater comprises a heat exchanger configured for use in a metal dusting environment.

17. A method for forming a carbon nanotube comprising: Using a feed gas to form a carbon nanotube in the first reactor; separating the carbon nanotubes from the reactor effluent to form a waste stream; heating the feed gas, drying the exhaust stream using waste heat from the waste stream Or both; and quenching the waste stream in an ambient temperature heat exchanger to condense water vapor to form the dry exhaust stream.

18. The method of paragraph 17, comprising feeding the dry waste stream to a second reactor; forming another portion of the carbon nanotubes in the second reactor; separating the carbon nanotubes to form a first a waste gas stream; heating the feed with waste heat from the second waste stream; and quenching the second waste stream in an ambient temperature heat exchanger to condense water vapor to form a second dry waste stream.

19. The method of paragraph 18, comprising compressing the second dry waste stream to form a compressed gas; passing the compressed gas through an ambient temperature heat exchanger to condense and remove any residual water vapor; fractionating the compressed gas To separate methane and carbon dioxide; and to add the methane to the feed gas.

20. A reaction system for forming a carbon nanotube comprising: two or more reactors configured to form a carbon nanotube from a gas stream comprising methane and carbon dioxide, wherein prior to the final reactor The effluent from each reactor is used as a feed stream to the downstream reactor, and wherein the effluent stream from the final reactor comprises a spent stream that is depleted of reactants; a separation system downstream of each reactor, wherein the separation system is configured to remove carbon nanotubes from the effluent from the reactor; a feed heater downstream of each separation system, wherein the feed heater includes A heat exchanger configured to heat a feed gas stream for a subsequent reactor using waste heat from the effluent of the reactor, and wherein the feed heater downstream of the final reactor is configured to be heated for use a gas stream of a first reactor; an ambient temperature heat exchanger downstream of each feed heater, wherein the ambient temperature heat exchanger is configured to remove water from the effluent to form a feed for subsequent reactors a compressor; the compressor configured to increase the pressure of the waste stream that is depleted of the reactant; an ambient temperature heat exchanger downstream of the compressor configured to remove water from the waste stream from which the reactant is depleted; a fractionation system configured to separate the reactant waste-laden waste stream into a methane-rich stream and a carbon dioxide-rich stream; and a mixer configured to incorporate the methane-rich stream or the carbon dioxide-rich stream Into the initial Flow.

21. The reaction system of paragraph 20, wherein one of the reactors comprises a fluidized bed reactor using metal beads as a catalyst.

22. The reaction system of paragraph 20 or 21, comprising a separation vessel downstream of each ambient temperature heat exchanger, wherein the separation vessel is configured to separate liquid water from the gas stream.

23. The reaction system of paragraph 20, 21 or 22, comprising a configuration A package heater that heats the initial feed stream for equipment startup.

24. The reaction system of paragraph 20, 21, 22 or 23, wherein the package heater is for heating a feed stream supplied to a subsequent reactor.

25. The reaction system of paragraph 23 or 24, wherein the package heater is configured as a field mounted heater, or is an electric heater, a commercially available heater configured to heat the gas, or any combination.

26. The reaction system of paragraph 23, 24 or 25, wherein the package heater is configured to heat the reducing gas stream without substantial damage.

While the present invention may be susceptible to various modifications and alternative forms, the specific examples discussed above are illustrative only. However, it should be understood again that such techniques are not intended to be limited to the particular embodiments disclosed herein. In fact, this technology includes all alternatives, modifications, and equivalents of the true spirit and scope of the patent application.

102/302/402/802‧‧‧ Feed gas

104/310/326/424/836‧‧‧ heat exchanger

106‧‧‧Hot

108‧‧‧heated feed gas

110‧‧‧Reactor

112/602‧‧‧Carbon nanotubes

114‧‧‧current flow

116/324/346‧‧‧Exhaust flow

118‧‧‧Water chiller

120/334/354‧‧‧ water

122‧‧‧Dry waste gas flow

124/368/434/508/800‧‧‧ gas fractionation system

126‧‧‧Recycling

128‧‧‧Excess feed

202‧‧‧Carbon

204‧‧‧ hydrogen

206‧‧‧Oxygen

208/210‧‧‧equal line

300/400/500‧‧‧Reaction system

304/504/850‧‧‧Recycled gas

306‧‧‧Static mixer

308‧‧‧Combined gas flow

312‧‧‧heated gas flow

314/341‧‧‧Package heater

316‧‧‧ hot gas flow

318/340/600‧‧‧ Fluidized Bed Reactor

320/342/620‧‧‧Reactor effluent logistics

322/344/430‧‧‧Locked addition funnel

328‧‧‧ cooled exhaust gas stream

330/350/362‧‧‧ ambient temperature heat exchanger

332/352/364/818/928‧‧‧Separation container

336‧‧‧Reaction Logistics

338/908‧‧‧heated stream

348‧‧‧ cooled waste stream

356‧‧‧Gas flow

358‧‧‧Compressor

360‧‧‧High pressure flow

366‧‧‧dry gas flow

370‧‧‧Excess feed

402‧‧‧High CO 2 content feed gas

404‧‧‧High methane recycle gas

406‧‧‧Multiple shell and tube heat exchangers

408‧‧‧second heat exchanger

410/414/426‧‧‧Ceramic soaking block heat exchanger

412/416‧‧‧ arrow

418‧‧‧Inlet valve

420‧‧‧Export valve

422‧‧‧Shell tube heat exchanger

426/1000‧‧‧Separation system

428‧‧‧Cyclone separator

432/1014‧‧‧Filter

436‧‧‧CO 2 waste stream

438/512‧‧‧fuel gas flow

440/510‧‧‧ flushing gas flow

506‧‧‧CH 4 waste stream

604/706‧‧‧ hot gas feed stream

606‧‧‧ pipeline

608‧‧‧Control valve

610‧‧‧Distributor board

612/702‧‧‧ Catalyst beads

614‧‧‧reactor wall

615‧‧‧ head end

616‧‧‧Top pipeline

618‧‧‧catalyst separator

622‧‧‧Recycling pipeline

708‧‧‧CNT

710‧‧‧catalyst particles

712‧‧‧ granules

714‧‧‧ grain boundaries

716‧‧‧Active Catalyst Particles

718‧‧‧H 2 O

720‧‧‧ cluster

804‧‧‧Dryer

806‧‧‧ Dry gas feed

808‧‧‧Cryogenic chiller

810‧‧‧Multi-stage quenching system

812‧‧‧Heat collection system

813‧‧‧Energy

816‧‧‧Quenched feed

820‧‧‧ liquid flow

822‧‧‧Vapor flow

824‧‧‧Expander

826‧‧‧Mechanical work

828‧‧‧Generator

830‧‧‧Two-phase flow

832/902/914‧‧‧ separation tower

834/906‧‧‧ reboiler

838‧‧‧ bottom stream

Section 840‧‧‧

842‧‧‧Export stream

844/910‧‧‧CO 2 product

846‧‧‧ Part 846 of the CO 2 product 844

848/912/922/930‧‧‧ top flow

904/916/934‧‧‧ bottom product stream

918/936‧‧‧ pump

920/938‧‧‧Return flow

924‧‧‧Quencher

926‧‧‧Nitrogen Freezer Unit

1002/1004‧‧‧Package column

1006‧‧‧Sampling valve

1008‧‧‧ barrel

1010‧‧‧ flushing flow

1012‧‧‧ rinse outlet flow

1016‧‧‧Washing and returning materials

1018‧‧‧Package valve

1020‧‧‧ CNT flow

1022‧‧‧fill station

The advantages of the present technology will be better understood by reference to the following detailed description and drawings.

1 is a block diagram of a reaction system for producing a carbon nanotube (for example, as a by-product of a carbon dioxide sequestration reaction); FIG. 2 is a balanced CHO equilibrium diagram between carbon, hydrogen, and oxygen, which is shown at various temperature conditions. a balanced species; Figure 3 is a simplified flow diagram of a reaction system for producing carbon nanotubes from a gas feed comprising carbon dioxide and methane; 4A, 4B and 4C are simplified flow diagrams of other reaction systems for producing carbon nanotubes from a gas feed comprising carbon dioxide and methane; Figures 5A, 5B and 5C are for feeding from a gas comprising carbon dioxide and methane A simplified flow chart of other reaction systems for making carbon nanotubes; Figure 6 is a diagram of a fluidized bed reactor for forming carbon nanotubes; and Figure 7 is a catalyst for forming carbon nanotubes on catalyst beads. Schematic diagram of the reaction; Figure 8 is a simplified flow diagram of a gas manufacturing procedure that can be used in a reactor system for making carbon nanotubes; Figure 9 is another gas manufacturing procedure that can be used in a reactor system for making carbon nanotubes. Simplified flow chart; Figure 10 is a simplified flow diagram of a separation system for separating a carbon nanotube from a reactor effluent stream; and Figure 11 is a method for producing a carbon nanotube from a feed gas comprising methane and carbon dioxide.

302‧‧‧ Feed gas

310,326‧‧‧ heat exchanger

324,346‧‧‧Exhaust flow

334, 354 ‧ water

368‧‧‧ gas fractionation system

300‧‧‧Reaction system

304‧‧‧Recycled gas

306‧‧‧Static mixer

308‧‧‧Combined gas flow

312‧‧‧heated gas flow

314,341‧‧‧Package heater

316‧‧‧ hot gas flow

318,340‧‧‧Fluidized bed reactor

320,342‧‧‧Reactor effluent logistics

322,344‧‧‧Locked addition funnel

328‧‧‧ cooled exhaust gas stream

330,350,362‧‧‧ ambient temperature heat exchanger

332,352,364‧‧‧Separate container

336‧‧‧Reaction Logistics

338‧‧‧heated stream

348‧‧‧ cooled waste stream

356‧‧‧Gas flow

358‧‧‧Compressor

360‧‧‧High pressure flow

366‧‧‧dry gas flow

Claims (26)

  1. A system for making a carbon nanotube comprising: a feed gas heater configured to heat a feed gas using waste heat from an exhaust stream; a reactor configured to form from the feed gas a carbon nanotube; a separator configured to separate the carbon nanotubes from the reactor effluent stream to form an exhaust stream; and a water removal system comprising an ambient temperature heat exchanger and configured to A large amount of water is separated from the exhaust stream to form a separator for the dry exhaust stream.
  2. The system of claim 1, wherein the ambient temperature heat exchanger comprises a water chiller.
  3. The system of claim 1, wherein the ambient temperature heat exchanger comprises an air cooled heat exchanger.
  4. A system as claimed in clause 1, which comprises a package heater configured to heat a feed gas for initial startup of the system.
  5. The system of claim 1, comprising a heat exchanger configured to heat the dry exhaust stream to form a second feed gas using waste heat from the exhaust stream; a second reactor configured Forming a carbon nanotube from the second feed gas; a separator configured to separate the carbon nanotubes from the effluent stream from the second reactor to form a second exhaust stream, and wherein The exhaust stream of the feed gas heater includes the second exhaust stream; and a water removal system configured to quench with an ambient temperature heat exchanger The second exhaust stream removes a quantity of water and separates water from the second exhaust stream to form a second dry exhaust stream.
  6. A system of claim 5, comprising a compressor configured to increase a pressure of the second dry exhaust stream; and a final water removal system configured to be removed from the second exhaust stream water.
  7. The patentable scope of application of the system of item 6, comprising a counter configured to separate by the second exhaust gas stream from the methane-enriched gas stream and the rich stream of the fractionation system 2 CO.
  8. A system of claim 7, comprising a mixing system configured to mix the methane-rich stream into the feed gas prior to the feed gas heater.
  9. The system of claim 7, wherein the gas fractionation system comprises a cryogenic condensation system configured to separate a gas condensable at a temperature from a gas that does not condense at the temperature.
  10. The system of claim 1, wherein the reactor is a fluidized bed reactor fluidizing a catalyst using a reverse flow of a feed gas.
  11. The system of claim 10, wherein the catalyst comprises metal spray beads.
  12. The system of claim 10, wherein the catalyst comprises metal beads comprising iron and nickel, chromium or any combination thereof.
  13. For example, the system of claim 10, wherein the catalyst comprises Metal beads having a size between about 25 mesh and 50 mesh.
  14. The system of claim 1, wherein the reactor is lined with a material configured to prevent degradation of the metal shell.
  15. The system of claim 1, wherein the pipe connection between the reactor and the cross heat exchanger is lined with a fire resistant material configured to protect the metal surface from degradation.
  16. The system of claim 1, wherein the feed gas heater comprises a heat exchanger configured for use in a metal dusting environment.
  17. A method for forming a carbon nanotube comprising: forming a carbon nanotube using a feed gas in a first reactor; separating the carbon nanotubes from the reactor effluent to form a waste stream; The waste heat of the waste stream heats the feed gas, the dry exhaust stream, or both; and quenches the waste stream in an ambient temperature heat exchanger to condense water vapor to form the dry exhaust stream.
  18. The method of claim 17, comprising: feeding the dry waste stream to a second reactor; forming another portion of the carbon nanotubes in the second reactor; separating the carbon nanotubes to Forming a second exhaust stream; heating the feed with waste heat from the second waste stream; and quenching the second waste stream in an ambient temperature heat exchanger to condense water vapor to form a second dry waste stream.
  19. The method of claim 18, comprising compressing the second dry waste stream to form a compressed gas; The compressed gas is passed through an ambient temperature heat exchanger to condense and remove any residual water vapor; the compressed gas is fractionated to separate methane and carbon dioxide; and the methane is added to the feed gas.
  20. A reaction system for forming a carbon nanotube comprising: two or more reactors configured to form a carbon nanotube from a gas stream comprising methane and carbon dioxide, wherein each reaction prior to the final reactor The effluent of the reactor is used as a feed stream to the downstream reactor, and wherein the effluent stream from the final reactor comprises a spent stream of reactant waste; a separation system downstream of each reactor, wherein the separation system is configured to The effluent from the reactor removes the carbon nanotubes; a feed heater downstream of each separation system, wherein the feed heater comprises waste heat that is configured to use the effluent from the reactor for subsequent use a heat exchanger for the feed gas stream of the reactor, and wherein the feed heater downstream of the final reactor is configured to heat the gas stream for the first reactor; ambient temperature heat downstream of each feed heater An exchanger wherein the ambient temperature heat exchanger is configured to remove water from the effluent to form a feed stream for a subsequent reactor; a compressor configured to increase waste of the reactants Pressure; ambient temperature heat exchanger downstream of the compressor, which is configured by opposing waste stream to remove water from the reaction of the lack of material consumption; gas fractionation system configured by opposing to the reaction of the waste stream of spent material consumption Separating into a methane-rich stream and a carbon dioxide-rich stream; and a mixer configured to blend the methane-rich stream or the carbon dioxide-rich stream to the initial feed stream.
  21. A reaction system according to claim 20, wherein one of the reactors comprises a fluidized bed reactor using metal beads as a catalyst.
  22. A reaction system according to claim 20, comprising a separation vessel downstream of each ambient temperature heat exchanger, wherein the separation vessel is configured to separate the liquid water from the gas stream.
  23. A reaction system according to claim 20, comprising a package heater configured to heat an initial feed stream for plant startup.
  24. The reaction system of claim 23, wherein the package heater is for heating a feed stream supplied to a subsequent reactor.
  25. The reaction system of claim 23, wherein the package heater is configured as a field-mounted heater, or is an electric heater, a commercially available heater configured to heat the gas, or any thereof combination.
  26. The reaction system of claim 23, wherein the package heater is configured to heat the reducing gas stream without substantial damage.
TW101143104A 2011-12-12 2012-11-19 Methods and system for forming carbon nanotubes TW201341609A (en)

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US8679444B2 (en) 2009-04-17 2014-03-25 Seerstone Llc Method for producing solid carbon by reducing carbon oxides
CN104271498B (en) 2012-04-16 2017-10-24 赛尔斯通股份有限公司 The method and structure of oxycarbide is reduced with non-iron catalyst
US9090472B2 (en) 2012-04-16 2015-07-28 Seerstone Llc Methods for producing solid carbon by reducing carbon dioxide
WO2013158161A1 (en) * 2012-04-16 2013-10-24 Seerstone Llc Methods and systems for capturing and sequestering carbon and for reducing the mass of carbon oxides in a waste gas stream
NO2749379T3 (en) 2012-04-16 2018-07-28
JP6379085B2 (en) 2012-04-16 2018-08-22 シーアストーン リミテッド ライアビリティ カンパニー Method for treating off-gas containing carbon oxides
US9896341B2 (en) 2012-04-23 2018-02-20 Seerstone Llc Methods of forming carbon nanotubes having a bimodal size distribution
US9604848B2 (en) 2012-07-12 2017-03-28 Seerstone Llc Solid carbon products comprising carbon nanotubes and methods of forming same
CN104619640B (en) 2012-07-13 2017-05-31 赛尔斯通股份有限公司 Method and system for forming ammonia and solid carbon product
US9779845B2 (en) 2012-07-18 2017-10-03 Seerstone Llc Primary voltaic sources including nanofiber Schottky barrier arrays and methods of forming same
WO2014085378A1 (en) 2012-11-29 2014-06-05 Seerstone Llc Reactors and methods for producing solid carbon materials
EP3129133A4 (en) 2013-03-15 2018-01-10 Seerstone LLC Systems for producing solid carbon by reducing carbon oxides
EP3113880A4 (en) 2013-03-15 2018-05-16 Seerstone LLC Carbon oxide reduction with intermetallic and carbide catalysts
IN2014CH03106A (en) * 2014-12-15 2015-05-22 Rao Mandapati Venkateswer

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US7138100B2 (en) * 2001-11-21 2006-11-21 William Marsh Rice Univesity Process for making single-wall carbon nanotubes utilizing refractory particles
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US20060100469A1 (en) * 2004-04-16 2006-05-11 Waycuilis John J Process for converting gaseous alkanes to olefins and liquid hydrocarbons
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