Apparatus and method for catalytic pyrolysis of light hydrocarbons

Abstract

1. A method for producing graphene and hydrogen, the method comprising: heating a hydrocarbon feed comprising light hydrocarbons to about 500°C to produce a preheated hydrocarbon feed; heating ferrocene in a first reactor to a temperature above the sublimation temperature of the ferrocene; introducing a portion of the preheated hydrocarbon feed into the first reactor, wherein the light hydrocarbons react with the ferrocene to produce a mixture comprising light hydrocarbon gas and sublimated ferrocene; combining the mixture comprising the light hydrocarbon gas and the sublimated ferrocene with the preheated hydrocarbon feed to produce a reactor feed stream; and introducing the main reactor feed to a second reactor operating at about 1000°C to produce a product mixture comprising hydrogen and solid carbon particles.

Description

[Technical Field]

[0001] This application relates generally to the production of carbon and hydrogen by the pyrolysis of hydrocarbons. More particularly, this disclosure relates to an apparatus and method for producing various forms of solid carbon by the pyrolysis of light hydrocarbons, such as methane, in the presence of a catalyst, and for isolating and recovering the hydrogen and the solid carbon produced. [Background technology]

[0002] Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a two-dimensional lattice. Since its inception, graphene has been found to be beneficial in many fields, including, but not limited to, water purification, medicine, architecture, electronic chips, and quantum computing. Each of these applications typically requires a graphene material with specific properties that can vary depending, for example, on the length and number of graphene layers that form the graphene material.

[0003] Some existing methods for forming graphene involve catalytic pyrolysis of hydrocarbons such as methane or natural gas into solid carbon and hydrogen. In such processes, the hydrogen produced is often an unused or unwanted by-product. Summary of the Invention [Problem to be solved by the invention]

[0004] Industrial demand for solid carbon and hydrogen continues to grow, and therefore there is a continuing need to develop improved methods and equipment for producing solid carbon and hydrogen.

[0005] Provided herein are methods and apparatus for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, onions, etc.) by pyrolysis of a hydrocarbon feedstock into hydrocarbons, as well as methods and apparatus for recovering hydrogen gas, a by-product of pyrolysis that may also be present in the hydrocarbon feedstock. [Means for solving the problem]

[0006] In one aspect, an apparatus for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen is provided, the apparatus comprising an elongated reactor having a first end and a second end, the first end configured to receive a hydrocarbon feedstock; a channel defined for conveying a fluid between the first end and the second end, the fluid being a reaction mixture comprising the hydrocarbon feedstock; a terminal compartment attached to the second end, the terminal compartment being selectively permeable to hydrogen gas and impermeable to other components of the reaction mixture; and a hydrogen collection compartment attached to the second end for receiving hydrogen gas from the terminal compartment, the hydrogen collection compartment being impermeable to hydrogen gas.

[0007] In one embodiment, the reactor further comprises an inlet between the first end and the second end for adding catalytic metal particles to the reaction mixture.

[0008] In another embodiment, the reactor is constructed of iron.

[0009] In yet another embodiment, the terminal section is constructed from stainless steel.

[0010] In yet another embodiment, the reactor further comprises at least one heating element for heating the reaction mixture within the channel.

[0011] In yet another embodiment, the reactor further comprises a sleeve disposed proximate to and surrounding the at least one heating element, the sleeve being constructed from a hydrogen-impermeable material and defining an enclosed space between the sleeve and the reactor.

[0012] In yet another embodiment, the hydrogen impermeable material is a ceramic material.

[0013] In yet another embodiment, the channels contain catalytic packing in the form of metal beads.

[0014] In yet another embodiment, the metal beads are iron.

[0015] In another aspect, a method for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen is provided, comprising: introducing a hydrocarbon feed into a first region of a reactor; heating the first region to about 300°C or greater to decompose the hydrocarbons and produce a reaction mixture containing initial carbon; introducing the reaction mixture into a second region of the reactor; heating the second region to about 1000°C or greater to react the initial carbon with catalytic metal particles to produce solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) fibers; and extracting hydrogen gas from the reaction mixture as the mixture exits the second region and contacts an end of the reactor coated with a material that is permeable only to hydrogen gas.

[0016] In one embodiment, the reaction mixture comprises co-transported catalytic metal particles / compounds.

[0017] In another embodiment, the interior surface of the second region is nucleated with metal catalyst particles / compounds before the hydrocarbon feed is introduced into the reactor.

[0018] In yet another aspect, a method for producing solid carbon and hydrogen is provided, the method comprising: heating a hydrocarbon feed comprising light hydrocarbons to about 500°C to produce a preheated hydrocarbon feed; heating one or more metal catalyst compounds in a first reactor to a temperature above the sublimation temperature of the one or more catalyst compounds; introducing a portion of the preheated hydrocarbon feed into the first reactor, where the light hydrocarbons react with the one or more metal catalyst compounds (which may initially be in the form of solid particles) to produce a mixture comprising light hydrocarbon gas and one or more sublimated metal catalyst compounds; combining the preheated hydrocarbon feed with the mixture comprising light hydrocarbon gas and the sublimated one or more metal catalyst compounds to produce a reactor feed stream; and introducing the main reactor feed to a second reactor operating at about 1000°C to produce a product mixture comprising the hydrogen and the solid carbon.

[0019] In yet another aspect, a method for producing solid carbon and hydrogen is provided, the method comprising: heating a hydrocarbon feed comprising light hydrocarbons to about 500°C to produce a preheated hydrocarbon feed; heating one or more metal catalyst compounds (which may initially be in the form of solid particles) in a first reactor to a temperature above the sublimation temperature of the one or more metal catalyst compounds; introducing the preheated hydrocarbon feed to the first reactor, wherein the light hydrocarbons react with the one or more metal catalyst compounds to produce a reactor feed stream comprising light hydrocarbon gases and sublimated metal catalyst compounds; and introducing the reactor feed stream to a second reactor operating at about 1000°C to produce a product mixture comprising the hydrogen and the solid carbon.

[0020] In yet another aspect, a method for producing solid carbon and hydrogen is provided, the method comprising: heating a hydrocarbon feed comprising light hydrocarbons to about 500°C to produce a preheated hydrocarbon feed; introducing solid particles of one or more metal catalyst compounds into the preheated hydrocarbon feed and suspending the solid particles in the preheated hydrocarbon feed using a vibratory or ultrasonic tool, thereby producing a reactor feed stream; and introducing the reactor feed stream to a second reactor operated at about 1000°C to produce a product mixture comprising the hydrogen and the solid carbon.

[0021] In yet another aspect, a method for producing solid carbon and hydrogen is provided, the method comprising introducing a hydrocarbon feed stream comprising light hydrocarbons into a catalytic pyrolysis reactor, the reactor being a packed bed reactor having solid particles comprising a metal catalyst compound, the particles having a size of about 5 mm to about 50 mm, or a fluidized bed reactor having particles comprising a metal catalyst compound having a size of about 1 mm to about 10 mm; and producing a product mixture comprising the hydrogen and the solid carbon.

[0022] In some embodiments, the metal catalyst compound comprises iron.

[0023] In some embodiments, the one or more metal catalyst compounds is ferrocene.

[0024] In some embodiments, the solid carbon comprises solid carbon (eg, graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.).

[0025] In some embodiments, the light hydrocarbons include methane.

[0026] In yet another aspect, an apparatus for catalytic pyrolysis of light hydrocarbons is provided, the apparatus having a first end and a second end, the first end configured to receive a feed comprising the light hydrocarbons; a channel defined for conveying a fluid between the first end and the second end, the fluid being a reaction mixture comprising the light hydrocarbons, the channel defined by a material permeable to hydrogen, the channel containing one or more metal catalyst compounds (which may be in the form of solid particles) that catalytically convert the light hydrocarbons to hydrogen and solid carbon; and a compartment or outlet for removing hydrogen that has passed through the hydrogen permeable material.

[0027] In some embodiments, the metal catalyst compound comprises iron.

[0028] In some embodiments, the one or more metal catalyst compounds is ferrocene.

[0029] In some embodiments, the solid carbon comprises solid carbon (eg, graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.).

[0030] In some embodiments, the light hydrocarbons include methane.

[0031] Hereinafter, embodiments will be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view of an exemplary embodiment of an apparatus for the production of solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 2] 1 is a cross-sectional view of another exemplary embodiment of an apparatus for the production of solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen, the apparatus further configured to control hydrogen content. [Figure 3] FIG. 1 shows a schematic of a reactor and heating system for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 4] FIG. 1 illustrates a system for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 5] FIG. 1 illustrates a system for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 6] FIG. 1 illustrates a packed bed reactor for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 7] FIG. 4 is a more detailed diagram of a process similar to that shown in FIG. 3. [Figure 8] FIG. 1 illustrates an exemplary embodiment of a reactor vessel for catalytic pyrolysis of hydrocarbons into solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 9] FIG. 1 illustrates another exemplary embodiment of a reactor vessel for catalytic pyrolysis of hydrocarbons into solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 10] FIG. 5 is a more detailed diagram of a process similar to that shown in FIG. 4. [Figure 11] FIG. 1 illustrates another exemplary embodiment of a process for catalytic conversion of a hydrocarbon feed to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 12] FIG. 1 illustrates yet another exemplary embodiment of a process for catalytic conversion of a hydrocarbon feed to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 13]FIG. 1 illustrates yet another exemplary embodiment of a process for catalytic conversion of a hydrocarbon feed to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 14] FIG. 1 illustrates yet another exemplary embodiment of a process for catalytic conversion of a hydrocarbon feed to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 15] FIG. 1 illustrates yet another exemplary embodiment of a process for catalytic conversion of a hydrocarbon feed to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. [Figure 16] FIG. 1 illustrates yet another exemplary embodiment of a process for catalytic conversion of a hydrocarbon feed to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. DETAILED DESCRIPTION OF THE INVENTION

[0033] Throughout this application, one or more of the terms "front," "rear," "back," "vertical," "vertically," "horizontal," "horizontally," "up," "down," "upward," "downward," "inward," "outward," "upper," "lower," "right," and "left" are used for convenience and to help describe features of the application, for example, as shown in the accompanying drawings.

[0034] Described below are methods and apparatus for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) by pyrolysis of hydrocarbons from a hydrocarbon feedstock, and for recovering hydrogen gas, a by-product of pyrolysis, that may be present in the hydrocarbon feedstock.

[0035] FIG. 1 illustrates an apparatus or reactor 10 for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. The reactor 10 includes a tube 12 defining a continuous gas passageway 3 between a first end, or inlet 1, of the tube 12 and a second end, or outlet 11. A hydrocarbon-containing feedstock 34 (also referred to herein as a "treat gas"), such as methane or natural gas, can flow through the inlet. A furnace 16 having a helical electrical resistance heating element 18 surrounds the reactor 10 to heat a first reaction zone 13 within the tube 12. Similarly, a second furnace 20 having a helical electrical resistance heating element 22 surrounds the reactor 10 to heat a second reaction zone 15 within the tube 12.

[0036] In alternative embodiments, there may be multiple tubes 12, and / or the tubes 12 may define a curved or straight continuous gas passage 3. Although two heating elements (18, 22) and furnaces (16, 20) are shown, the reactor 10 may have any number of heating elements / furnaces (collectively "heating elements"). The heating elements may be of any suitable type, such as, for example, standard induction heating elements or flame heating elements.

[0037] Heating elements 18 and 22 may be heated to suitable temperatures to establish a desired temperature profile within tube 12 and produce solid carbon (e.g., graphite, graphene, carbon fibers, carbon nanotubes, fullerenes, etc.). For example, elements 18 and 22 may be operated so that tube 12 exhibits a lower temperature (e.g., 300°C) in zone 13 near inlet 1 and a higher temperature (e.g., 1000°C) in zone 15 near outlet 11. The hydrocarbon feedstock 34 may be diluted with other gases, such as hydrogen. The flow rate of feedstock 34 into tube 12 may be adjusted as desired. Higher flow rates of feedstock 34 entering tube 12 may result in longer and / or thinner graphene fibers 6 and other solid carbon products. Various elements, primarily metals, may be combined with gas stream 3 in zone 13, for example, in the form of organic or inorganic salts.

[0038] In some embodiments, iron pentacarbonyl vapor may be provided in or upstream of zone 13. As the gas flows through heated zone 13, the metal compound, in this example an iron compound, decomposes to produce iron particles 36, the size of which is exaggerated in Figures 1 and 2 for ease of illustration. The metal catalyst compound may be iron, as previously discussed, and may hereinafter also be referred to as "catalyst."

[0039] Iron particles 36 may be entrained in the gas stream and transported through the tube 12 toward the outlet 11. Methane may be cracked from the natural gas within the heating zone 15. The resulting initial carbon may react with the iron particles 36 to produce fine graphene filaments 6. Any produced graphene filaments 6 may be thickened by depositing additional initial carbon onto them with additional individual filaments. Once the reaction is complete, the graphene filaments 6 and / or any other produced solid carbon subspecies may be recovered in any suitable manner. For example, a suitable tool, such as a ring or set of rings configured to be inserted into the tube 12, may be used to scrape or knock the solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) off the inner wall of the tube 12.

[0040] Reactor 10 has an end section 7, which may be constructed of a material that is permeable to hydrogen gas and substantially or completely impermeable to other gases within tube 12, such as methane or inert gases. End section 7 may be attached (e.g., threaded or welded) to outlet 11 of tube 12. During pyrolysis of the hydrocarbon feedstock, hydrogen passes through end section 7 (see arrow 19) and enters hydrogen collection section 2, which may be constructed of a material that is impermeable to or resists the passage of hydrogen, such as a ceramic material or iron. Hydrogen 5 then exits collection section 2 via outlet 4 defined in collection section 2 and may be further processed or stored (not shown).

[0041] Under certain conditions, such as high temperature and / or pressure, tube 12, constructed of iron in this exemplary embodiment, may be permeable to some hydrogen. Therefore, if desired, device 10 may include an impermeable (to hydrogen) sleeve 8 disposed around tube 12 and heater 20 to collect any hydrogen that may pass through tube 12. Sleeve 8 may be constructed of or include a hydrogen-impermeable material, such as, for example, a ceramic material or iron. Any number of such sleeves 8 may be provided as desired.

[0042] Referring to FIG. 2 , the apparatus 10 may further include one or more hydrogen collection lines 35 constructed of a hydrogen-permeable material, such as 304 stainless steel. The lines 35 can be used to remove hydrogen from within the tubes 12, providing some control over the hydrogen content within the reactor 10, which may be beneficial for the pyrolysis reaction. Such lines 35 may also increase turbulence within the tubes 12. Increased turbulence may enhance the uniformity of graphene distribution on the walls of the tubes 12. Other components or modifications to the tubes 12 may be used alone or in combination with the lines 35 to increase turbulence therein. In certain embodiments, plasma heating and / or microwave heating may be used alone or in combination with the aforementioned heaters. In some embodiments, the tubes 12 may be constructed of a ceramic material or another material impermeable to hydrogen gas. In some embodiments, a graphene (and other solid carbon subspecies) collection device, such as a fabric or mesh filter, may be installed within the tubes 12. In some embodiments, tube 12 is a tubular iron reactor, and graphene fibers 6 and other solid carbon sub-species may grow on the interior walls of tube 12, primarily within region 15. The predominant location of graphene fibers 6 and / or growth / deposition or other solid carbon sub-species may vary depending on factors such as the dimensions of tube 12 and the temperature profile therein.

[0043] Various metal particles can be obtained from suitable precursor compounds and used as nuclei for graphene filament formation. For example, iron particles can be formed by evaporating a ferric nitrate solution on a suitable surface and decomposing the resulting iron oxide residue. Nucleation effectiveness depends at least in part on the metal particle size; therefore, the metal particle size (degree of elemental metal agglomeration) can be adjusted, for example, depending on the desired graphene filament growth rate and properties. As will be appreciated by those skilled in the art, the dissociation rate and particle formation rate are temperature-dependent and may vary depending on the metal precursor used. Generally, one or more variables, such as the temperature profile across the tube 12, the dimensions and configuration of the tube 12, the location of introduction of the metal precursor, the type of metal nuclei, and the flow rate of the gas stream, can be adjusted to obtain the desired type of graphene.

[0044] In some embodiments, fibers may be grown on the interior surface of the tube 12 on which metal nuclei have been deposited. Prior to the initiation of pyrolysis, the interior wall may be nucleated by in-situ decomposition of a metal precursor compound, such as an iron carbonyl compound. In one embodiment, the metal precursor may be iron pentacarbonyl, Fe(CO), which may be injected into a stream of inert gas (e.g., argon) at ambient temperature, after which the iron carbonyl evaporates. The inert gas stream carries vapors into the reactor, and the flow rate of the stream may be controlled to achieve a desired dispersion of iron particles within the tube 12.

[0045] As described below, in some embodiments, the catalyst reacts with a stream (102) that is primarily composed of methane gas and may contain small amounts of other hydrocarbon gases, such as ethane, propane, or other gases often found in trace amounts in oil field produced gas. Gases added to or contained in the oil field gas may be HS, mercaptans, and / or other sulfur-containing compounds. Such sulfur gases may be important in forming various types of graphite, graphene, and other solid carbon subspecies.

[0046] In some embodiments, as shown in FIG. 3 , which illustrates a reactor system 100, the catalyst is provided as a gas suspension, which may be mixed with a feed stream 102 (which may be referred to as “methane gas” or “methane gas stream”), which may consist primarily of methane gas preheated to 500° C. in a heater (110). The feed stream 102 may be at ambient temperature prior to preheating in the heater 110. Two or more preheaters may be included. A portion of the methane gas stream (i.e., the feed stream 102) may first be diverted through a catalyst solution 118 and bubbled through a liquid to support the suspended catalyst. A diffuser 116 may be used to bubble the liquid through the liquid catalyst solution 118 in another vessel 108. The mixed stream 106 then enters an open reactor 114, where it may be heated to 950 to 1100° C. depending on the catalyst used. A preheater 110 (which may be, for example, a resistance heater, an induction heater, a plasma heater, a microwave heater, or a flame-source heater) may form a preheat reactor feed 112 that enters an open reactor 114. In such a reactor 114, solid carbon, such as graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc., may be formed along with hydrogen, methane, and reaction by-products, more generally, as output 120 of the reactor system 100 shown in Figure 3. If required, this may include a liquid catalyst recycle in addition to the preheater 110, as previously described.

[0047] Alternatively, the catalyst may be distributed throughout the reactor 114, either alone or in combination with features of the liquid catalyst solution 118. This may be accomplished by installing a metal grid or in a manner similar to that used with latch rings in distillation columns of various sizes and shapes. Using this method, the reactor may be quickly opened, and most or all of the catalyst matrix may be easily and / or quickly drained and replaced with fresh catalyst. In this exemplary embodiment, larger stripes or fragments of graphite, graphene, and other carbon subspecies may be produced. The operating temperature may be between 950°C and 1050°C.

[0048] The catalyst may also be introduced by wetting the walls of the reactor 114 with a catalyst solution. The reactor 114 may be operated at 950 to 1150°C, and the gas feed may be preheated to 500°C before entering the reactor. This method may produce solid carbon containing a mixture of graphite and graphene in sizes ranging from 8 cm in length to 3 to 6 microns in length.

[0049] As shown in FIG. 4, the reactor system 100 may be part of a system for producing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen 300. The system 300 may include a filtration system 306 that receives the output 120 of the reactor system 100. The filtration system 306 may include one or more filters (e.g., a coarse filter 304 and a fine filter 308) that taper toward an outlet. The filtration system 306 may be closed as needed and periodically opened to remove the solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) therefrom, e.g., by shaking or vibration, to produce an outlet stream of gas, which may contain trace amounts of solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) (312), which may be further filtered, if needed, using an electrostatic filter 314. This may be emptied, e.g., by periodically shaking or vibrating. The gas 316, which is substantially or completely free of solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.), may then be conveyed to a heat exchanger 320 and cooled to produce a cooled outlet gas 322, which may contain hydrogen and methane. The outlet gas may then be conveyed to a filtration system, such as a pressure swing absorption (PSA) system 324, to produce hydrogen 326, which may be conveyed to storage 330. The PSA system 324 may also produce a recycled hydrocarbon feed 328 that is returned to the reactor system 100. If desired, the inlet feed 102 may be heated by the heat exchanger 320 to produce a preheated stream 112, which may be combined with the recycled stream 328 to produce a combined recycled preheated stream 113. If desired, the recycled preheated stream 113 may be further preheated within the reactor system 100.

[0050] As shown, multiple filters may be used to separate solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) from hydrocarbon / hydrogen gas, starting with a coarse filter, followed by a finer filter, then another finer filter, and so on until all solid carbon material is removed. Each coarse filter may retain some of the fine carbon material, and the final filter may be one micron or smaller and may work in conjunction with one or more other filters, so that one is being filtered while the other is being purified. The final filter may have a dead zone to allow the carbon to settle before it. If necessary, an electrostatic precipitator separator may be included.

[0051] Once the solid carbon is removed, the hydrocarbon stream (which may consist primarily of methane) and hydrogen gas may proceed to either a pressure swing absorption system or a membrane separation system, which separates the hydrogen and hydrocarbon gases. The membrane separation system provides hydrogen at or near 99.99% purity, and all other gases may be recycled. Because gas separation systems tend to have difficulty at high temperatures, a cooling stage before separation and a heating stage for the recycled hydrocarbon gas before returning it to the reactor feed may be provided. Pipes may be used for heating and cooling the inlet gas, or to use the inlet gas to heat the outlet gas to the reactor. Any remaining heat may be used to heat the original gas feed.

[0052] FIG. 5 shows another exemplary embodiment of a system including a hydrocarbon feed 402 (as described above) that produces solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. This hydrocarbon feed 402, optionally combined with a recycle stream, produces feed 401, which may be introduced into a fluidized-bed reactor 400 containing a metal catalyst. Feed 402 may proceed through the metal catalyst to produce a mixture of solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.), hydrocarbons, hydrogen, and other by-products (stream 404). The reactor may include a catalyst deposited on the reactor walls instead of or in combination with a catalytic fluid and / or have the catalyst in the form of an aerosol mixed with the feed upon entering reactor 400. Stream 404 is then introduced into a preheater 406, which may be heated by any of the means described above and, if necessary, may include an acoustic wave element to facilitate the passage of the produced solids. The preheated stream 408 produced by the preheater 406 may then be introduced into another heater 410, which may include an acoustic element (not shown) to facilitate the passage of generated solids, as described above. Any vessel described herein that may benefit from including an acoustic element to facilitate the passage of solids (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) (i.e., to generate vibrations of the vessel) may include such an acoustic element. If desired, the heater 410 may be, for example, a reactor, such as that described in FIG. 6, which produces a first hydrogen stream 412 and an output stream 414 of first hydrogen, hydrocarbons, and solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.). Stream 414 may be sent to a solids separator 416 (which may be any vessel suitable for separating solid carbon from hydrocarbons and residual hydrogen), which may then produce solids 420 for storage in a solids storage unit 418.Separator 416 may also produce a hydrogen and hydrocarbon stream 422, which then enters a hydrocarbon / hydrogen separation unit 424 (which may be, for example, a PSA unit) to produce a purified hydrogen stream 426, which may be combined with first hydrogen stream 412 to produce a purified hydrogen stream that is stored in hydrogen storage vessel 430. The separator may also produce a hydrocarbon recycle stream, which may be passed through compressor 407 to produce compressed hydrocarbon recycle stream 409, which may be combined with feed 402 to form feed 401. As previously mentioned, hydrogen stream 412 is optional and may be used alone or in addition to or in combination with reactor-type vessels (e.g., as shown with respect to FIG. 6 ).

[0053] FIG. 6 illustrates a reactor that may be used as the heater 410 described above, or that may be suitable for implementation in other processes described herein and variations thereto that will be apparent to one skilled in the art. The reactor 500 may receive a hydrocarbon feed 502 containing primarily methane, which may further include other light hydrocarbon gases such as ethane and propane, as well as any other suitable additives that may promote the formation of graphene and other carbon subspecies, as described above. The reactor may have a selectively permeable reactor core 504 containing a metal, preferably iron, catalyst packing 506 (e.g., a catalyst described above). The core 504 may be permeable to hydrogen gas that exits the core 504 and is introduced into a space 514, and / or may be released directly from the reactor. The reactor may be heated by an induction coil 512, as shown in FIG. 6, and / or by other suitable means. A product stream 510 comprising hydrocarbons, residual hydrogen, and solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) exits core 504 and may be delivered for further processing (e.g., utilizing processes / vessels described herein).

[0054] FIG. 7 is a more detailed version of a process similar to that shown in FIG. 3, including the same reference numbers for similar elements and including additional details regarding process conditions (e.g., temperature, pressure, and flow ratio of stream 122).

[0055] 8 shows an exemplary embodiment of a reactor vessel 600. A hydrocarbon feed (e.g., feed 102) may be converted to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.), hydrogen, and residual hydrocarbons. Vessel 600 may have steel wool or another form of metal matrix to facilitate the conversion of hydrocarbons to solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.). Vessel 602 is a drawing of vessel 600, showing how the gas feed can enter the side of the reactor, and the top of the reactor may be opened, and the catalyst matrix and / or packing may be changed, as needed.

[0056] 9 illustrates another exemplary embodiment of a reactor vessel 604 for catalytic pyrolysis of hydrocarbons into hydrogen and solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.). The catalyst may be introduced at the top of the reactor and deposited on the reactor walls. As shown, the feed (e.g., feed 102) may be introduced at the top of the vessel 604.

[0057] FIG. 10 is a more detailed version of a process similar to that shown in FIG. 4, including the same reference numbers for similar elements and including additional details regarding process conditions (e.g., temperature, pressure, and flow ratio of stream 122).

[0058] FIG. 11 illustrates another exemplary embodiment of a process for catalytic conversion of a hydrocarbon feed 702, primarily comprising methane, to hydrogen and solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.). As shown, the feed 702 may be heated, may have a catalyst introduced therein, and then may be introduced into a reactor vessel 700. The heated feed combined with the catalyst may be introduced into a tube matrix 708, where the hydrocarbon may be preceded by a surrounding space 710, similar to a shell-and-tube heat exchanger arrangement. A heated fluid may be heated, for example, by a heater 706, and then circulated through the space 710. The heated fluid may be, for example, a molten salt. The hydrogen and solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) may be collected in a tank 712, from which the hydrogen may be transferred to a hydrogen reservoir.

[0059] FIG. 12 illustrates a process 800 for the sublimation (pyrolysis) of ferrocene into an uncombusted process methane stream. A light hydrocarbon feedstock, or process gas 801 (described above), may be introduced into a preheater 802, which may preheat the process gas 801 to above 500°C, producing a preheated stream 803. The preheated stream 803 is introduced into a pressurized vessel or apparatus (first reactor 804), which may be a catalytic reactor. The first reactor 804 may be externally heated and filled with solid ferrocene and / or other suitable metal catalyst compounds, which may be present, for example, as solid particles. The first reactor 804 is heated, for example, by resistive or inductive methods, to heat the ferrocene therein to a temperature above its sublimation temperature, which may vary depending on the pressure within the first reactor 804. The temperature within the first reactor 804 may be maintained at, for example, 500°C. Preheated stream 803 may be introduced into one end of first reactor 804 and contacted with heated ferrocene. A mixture containing saturated gas and sublimated ferrocene 805 may then be discharged from first reactor 804 and reintroduced into preheated stream 803 to produce feed stream 806 for second reactor 807, which may operate at, for example, 1000°C. In second reactor 807, pyrolysis may occur, thereby forming product mixture 808 containing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.), hydrogen, and residual hydrocarbons. Separation of at least the hydrogen from product mixture 808 may be performed downstream.

[0060] 13 illustrates process 810. Process 810 differs from process 800 in that it has a first reactor 804 vessel large enough to produce a mixture 815 containing saturated gas and sublimated ferrocene that can be fed directly to a second or main reactor 816, instead of a slipstream or partial mass flow through a smaller catalytic sublimation device (i.e., first reactor 814). Main reactor 816 may be operated at, for example, 1000° C., and may produce a product mixture 817 containing solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.), hydrogen, and residual hydrocarbons.

[0061] FIG. 14 illustrates another process 820 for catalytic pyrolysis of light hydrocarbons to produce solid carbon (e.g., solid carbon and / or hydrogen). In process 820, solid particulate ferrocene may be introduced into preheated stream 803 for a non-combustion pyrolysis reaction. In process 820, equipment 818 may introduce solid particulate ferrocene and / or similar catalytic compounds into preheated stream 803 to assist in the conversion of light hydrocarbons (e.g., methane) to hydrogen and solid carbon particles. Such equipment 818 may use a vibratory or sonic tool to suspend particles swept within the methane process stream, producing a feed stream 819 for sublimation and reaction in main pyrolysis reactor 821. Equipment 818 may include, for example, a venturi delivery system and a grinding wheel. Reactor 821 may produce a product mixture 822 including solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.), hydrogen, and residual hydrocarbons.

[0062] 15 illustrates yet another process 830 for catalytic pyrolysis of light hydrocarbons to produce solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. The process 830 includes a primary reactor 835, which may be, for example, a packed-bed reactor, whereby a pressure vessel is filled with solid ferrocene and may be resistively or inductively heated. The process gas stream 801 may be introduced, without preheating if desired, into the primary reactor 835 where catalytic pyrolysis may occur. The ferrocene particles may vary in size and, in addition to catalyzing the pyrolysis, may also serve as a source of heat exchange (i.e., a heat source for the light hydrocarbons in the reactor 835).

[0063] 16 illustrates yet another process 840 for catalytic pyrolysis of light hydrocarbons to produce solid carbon (e.g., graphite, graphene, carbon fiber, carbon nanotubes, fullerenes, etc.) and hydrogen. Process 840 is similar to process 820, except that one or more apparatus 918 for introducing solid particulate ferrocene and / or similar catalytic compounds is located before preheater 802, which may operate at, for example, 500°C. A feed stream 903 for reactor 821 exits preheater 802, and includes heated light hydrocarbons and catalytic particles / compounds suspended therein. In some embodiments, one or more apparatus 918 may be located before and / or after preheater 802.

[0064] In some embodiments, primary reactor 835 may be a fluidized bed reactor. In embodiments where a fluidized bed is used, solid ferrocene particles may be smaller and suspended in the light hydrocarbon gas stream within reactor 835, as compared to ferrocene used in a packed bed reactor. Such suspended particles may be removed from the pressure containment vessel (reactor 835) by, for example, distillation or mechanical separation. In some embodiments, heat from the gaseous component of the product stream (i.e., the exhaust from the pyrolysis reactor) may be used alone or in combination with a preheater to heat the inlet process gas.

[0065] 12-16 may be heated inductively, resistively, or by any other suitable method (e.g., another method described above). Metal catalyst compounds (e.g., other ferrous catalysts) may be used in place of or in combination with ferrocene in the processes described herein.

[0066] The term "metal catalyst compound" as used herein is understood to refer to any catalyst compound capable of catalyzing the thermal cracking of hydrocarbons. Surprising results have been found when ferrocene is used alone as the catalyst compound. It has been found that the use of ferrocene alone as the metal catalyst compound can substantially increase the efficiency of the thermal cracking of light hydrocarbons while reducing reactor fouling. In some cases, the use of ferrocene alone has approximately doubled the efficiency of the thermal cracking of light hydrocarbons. The use of ferrocene in part, rather than alone, also significantly improves results.

[0067] Where considered appropriate for simplicity and clarity of description, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. Additionally, numerous specific details are described in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those skilled in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures, and materials have not been described in detail so as not to obscure the embodiments described herein. Additionally, the description should not be considered to limit the scope of the embodiments described herein.

[0068] The examples and corresponding figures used herein are for illustrative purposes only. Different configurations and terminology may be used without departing from the principles described herein. For example, components and modules may be added, removed, modified, or arranged in different connections without departing from these principles.

[0069] The steps or operations in the flowcharts and figures described herein are merely examples. There may be many variations on these steps or operations without departing from the principles described above. For example, the steps may be performed in a different order, or steps may be added, deleted, or modified.

[0070] While the foregoing principles have been described with reference to particular embodiments, various modifications, such as those set forth in the appended claims, will be apparent to those skilled in the art.

Claims

1. 1. A method for producing solid carbon and hydrogen, comprising: heating a hydrocarbon feed comprising light hydrocarbons to about 500°C to produce a preheated hydrocarbon feed; heating one or more metal catalyst compounds in a first reactor to a temperature above the sublimation temperature of the one or more metal catalyst compounds; introducing a portion of the preheated hydrocarbon feed into the first reactor, wherein the light hydrocarbons react with the one or more metal catalyst compounds to produce a mixture comprising light hydrocarbon gases and one or more sublimated metal catalyst compounds; combining the mixture comprising light hydrocarbon gas and the sublimated one or more metal catalyst compounds with the preheated hydrocarbon feed to produce a reactor feedstream; introducing the primary reactor feed into a second reactor operated at about 1000°C to produce a product mixture comprising hydrogen and the solid carbon; A method comprising:

2. 1. A method for producing solid carbon and hydrogen, comprising: heating a hydrocarbon feed comprising light hydrocarbons to about 500°C to produce a preheated hydrocarbon feed; heating one or more metal catalyst compounds in a first reactor to a temperature above the sublimation temperature of the one or more metal catalyst compounds; introducing the preheated hydrocarbon feed into the first reactor, wherein the light hydrocarbons react with the one or more metal catalyst compounds to produce a reactor feed stream comprising light hydrocarbon gases and sublimated metal catalyst compounds; introducing the reactor feed stream, including the solid carbon and the hydrogen, into a second reactor operated at about 1000°C to produce a product mixture; A method comprising:

3. 1. A method for producing solid carbon and hydrogen, comprising: heating a hydrocarbon feed comprising light hydrocarbons to about 500°C to produce a preheated hydrocarbon feed; introducing solid particles comprising one or more metal catalyst compounds into the preheated hydrocarbon feed and suspending the solid particles in the preheated hydrocarbon feed using a vibratory or ultrasonic tool, thereby producing a reactor feedstream; introducing the reactor feed stream into a second reactor operating at about 1000°C to produce a product mixture comprising the hydrogen and the solid carbon; A method comprising:

4. 1. A method for producing solid carbon and hydrogen, comprising: introducing a hydrocarbon feed stream comprising light hydrocarbons into a catalytic pyrolysis reactor; The reactor comprises: a packed bed reactor having solid particles comprising a metal catalyst compound, the solid particles having a size of about 5 mm to about 50 mm; or a fluidized bed reactor having solid particles comprising a metal catalyst compound, said solid particles having a size of about 1 mm to about 10 mm; and wherein a product mixture is produced comprising said hydrogen and said solid carbon.

5. 5. The method of claim 1, wherein the one or more metal catalyst compounds comprises iron.

6. 5. The method of claim 1, wherein the one or more metal catalyst compounds is ferrocene.

7. 5. The method of claim 1, wherein the solid carbon comprises graphene, graphite, carbon nanotubes, carbon fibers, and / or fullerenes.

8. 5. The method of claim 1, wherein the light hydrocarbons comprise methane.

9. 1. An apparatus for catalytic pyrolysis of light hydrocarbons, comprising: a first end and a second end, the first end configured to receive a feed comprising the light hydrocarbons; a channel defined for conveying a fluid between the first end and the second end, the fluid being a reaction mixture comprising the light hydrocarbons, the channel being defined by a material permeable to hydrogen, the channel having solid particles comprising one or more metal catalyst compounds for catalytically converting the light hydrocarbons to hydrogen and solid carbon; a compartment or outlet for removing hydrogen passing through said hydrogen permeable material; Equipment having:

10. 10. The device of claim 9, wherein the one or more metal catalyst compounds comprise iron.

11. 11. The apparatus of claim 9 or 10, wherein the one or more metal catalyst compounds is ferrocene.

12. 11. The device of claim 9 or 10, wherein the solid carbon comprises graphene, graphite, carbon nanotubes, carbon fibers, and / or fullerenes.

13. 11. The apparatus of claim 9 or 10, wherein the light hydrocarbons include methane.

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