Hydrocarbon decomposition with aerosolized catalyst

Abstract

Producing hydrogen gas includes combining a gaseous feedstock stream with a particulate catalyst, wherein the gaseous feedstock stream comprises a gaseous hydrocarbon, and the particulate catalyst is selected to promote decomposition of the gaseous hydrocarbon; entraining the particulate catalyst in the gaseous feedstock stream to yield an aerosolized reaction mixture comprising aerosolized catalyst particles; and heating the aerosolized reaction mixture to decompose the gaseous hydrocarbon, thereby yielding a product stream comprising elemental carbon and hydrogen gas.

Description

Attorney Docket No.: 44807-0480W01 / JHU C18203HYDROCARBON DECOMPOSITION WITH AEROSOLIZED CATALYSTCROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Patent Application No. 63 / 636,940 filed on April 22, 2024, which is incorporated by reference herein in its entirety.FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made in part with United States Government support under contract DE-AR0001019 awarded by the Advanced Research Projects Administration - Energy, part of the U.S. Department of Energy. The U.S. Government has certain rights in the invention.TECHNICAL FIELD

[0003] The presently disclosed subject matter provides a process to produce hydrogen and solid carbon from hydrocarbons.BACKGROUND

[0004] Hydrocarbons such as methane, ethane, propane, higher alkanes, isomers thereof, and polymers such as polyethylene are molecules that contain only carbon and hydrogen as elemental components. Many fuels comprised of hydrocarbons create significant quantities of greenhouse gasses such as carbon dioxide when they are combusted. Methods including plasma decomposition, molten bubbler reactors, and thermocatalytic decomposition have been used to split apart hydrocarbons into solid carbon and hydrogen. The hydrogen can be used as a clean burning fuel, and the solid carbon can be used or sequestered.SUMMARY

[0005] This disclosure describes a process for hydrocarbon decomposition in which an aerosolized catalyst powder is entrained in an inlet gas stream of a reactor. As used herein, "‘entrained’7powder generally refers to powder having a particle size small enough such that the particles move with the gas stream at the same velocity as the gas stream. Suitable powders include carbon nanoparticles (e.g., carbon black), as well as composites of metal and carbon, and other powders that can be entrained in the gas and absorb heat. Especially for carbon and metal-based powders, entrained aerosolized powder particles are very’ efficient heat absorbers, and this heat can be efficiently coupled to the carrier gas. As a result.Attorney Docket No.: 44807-0480W01 / JHU C18203 temperature profiles in the reactor are more controlled and uniform than when using fluidized beds, and uniformity of powder morphology can be maintained.

[0006] For a hydrocarbon decomposition reactor with aerosolized powder, heat may be supplied in multiple heating zones. In one example, electric heaters in a first heating zone bring the powder and gas up to the desired reaction temperature, and heat is supplied by electric heaters in a second heating zone to maintain the reaction temperature. Because the concentration of powder particles is low in the gas stream, there tends to be reduced powder build-up.

[0007] Upon exit from the reactor volume, the gas and powder stream can be cooled by conventional heat exchangers and separated using filters. In some cases, the powder upon exit of the reactor can be re-entrained in a flowing gas and re-used by re-introducing the powder back into the inlet of the reactor. In certain cases, the powder particles increase in size due to carbon deposition and can no longer be entrained in a flowing gas. Entrainable and non-entrainable powder can be separated by filtration. The non-entrainable powders can be ground up, breaking them into smaller particles that can again be entrained in the gas and recycled into the reactor. Entrainment into the inlet gas stream to aerosolize the particles can in some cases be spontaneous, but in other cases can be aided by agitation of the gas / powder mixture by physical mechanisms. Ultrasonic transducers placed in the gas stream or against the tubes carrying the gas and powder can be used to break up non-aerosolized clumps of catalyst for entrainment as an aerosol in the gas stream.

[0008] The use of an aerosolized catalyst in the input stream of hydrocarbon decomposition can also improve the overall thermal efficiency of reactor systems through recuperative heat exchange, in which the inlet stream is preheated by using it to cool the outlet stream of the reactor. The working temperature of a methane decomposition reactor may vary from 800 °C to over 2000 °C, depending on the configuration of the reactor. Thus, it can be advantageous to cool the hydrogen reaction stream by heat exchange with the methane inlet stream, heating the methane to as close to the working temperature as possible. However, uncatalyzed methane decomposition will occur on the hot walls of the heat exchanger at temperatures above 500 °C. This process tends to form tar-like deposits that clog the tubes over time - commonly referred to as “fouling” - and for at least this reason, methane is typically not pre-heated above 500 °C. However, by using an aerosol methane decomposition catalyst in the inlet stream, the deposition typically occurs on the aerosol particles as the temperature heats up, at least because the aerosol particles provide a greater surface area than the tube walls. Thus, undesired methane decomposition in the heatAttorney Docket No.: 44807-0480W01 / IHU C18203 exchanger can be avoided, and waste heat from the reactor can be efficiently transferred to the methane + catalyst inlet stream. This effect can significantly improve the overall system efficiency.

[0009] The details of one or more embodiments of the subject matter of this disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.BRIEF DESCRIPTION OF DRAWINGS

[0010] FIG. 1 shows a schematic representation of an example chemical reactor in which gas and gas-entrained aerosol powder are simultaneously introduced into the reactor.

[0011] FIG. 2 shows a schematic representation of an example chemical reactor in which gas and gas-entrained aerosol powder are simultaneously introduced into a heat exchanger prior to entering the reactor, drawing off heat from the exit stream.

[0012] FIG. 3 shows a schematic wherein the heating elements in configuration (a) are inside the reactor vessel and in configuration (b) are outside the vessel.

[0013] FIG. 4 shows a schematic. In configuration (a), the first zone is heated by microwave and the second zone by resistive heating elements. In configuration (b), heating is accomplished by radiative heating elements or radiative tubes through which hot sand or molten salt is circulated in the reactor.

[0014] FIG. 5 shows the reactor comprising of (a) pre-heat zone, (b) reaction zone, and (c) adiabatic zone.

[0015] FIG. 6 shows the reactor system, which comprises a partial catalyst recirculation loop that passes through a mechanical mill.

[0016] FIG. 7 shows a schematic showing the powder injector system into the aerosol chamber, which could be a spray dryer, eductor, or a venturi powder sprayer that can operate either as a continuous injector or a pulsed injector.

[0017] FIG. 8 shows a schematic where, in configuration (a), powders are aerosolized with an internal ultrasonic horn, and in (b), an external ultrasonic horn is used to aerosolize powders.

[0018] FIG. 9 show s a schematic in which, in configuration (a), powders are aerosolized with an electrostatic field generator. In configuration (b), pow ders are aerosolized by impacting them onto a deflection surface.Attorney Docket No.: 44807-0480W01 / JHU C18203

[0019] FIG. 10 shows a schematic of the aerosol chamber in configuration (a) the powders are aerosolized by impacting the powder mixture onto an upright cone deflection surface, and in configuration (b) the deflection surface is an inverted cone.DETAILED DESCRIPTION

[0020] FIG. 1 shows a detailed schematic of a reactor system 100 for hydrocarbon decomposition with aerosolized catalyst powder. Feedstock is provided to the reactor system through one or more of streams through one or more of inlets 101, 102, and 103. Inlet 101 provides the feedstock to a catalyst powder hopper 104. Inlet 102 provides the feedstock to the system downstream from the catalyst powder hopper 104, and inlet 103 provides the feedstock to the reactor 107.

[0021] In some cases, the feedstock consists of, consists essentially of, or includes gaseous hydrocarbons (e.g., methane). In some implementations, the feedstock includes heavier hydrocarbons (e.g., ethane, propane, butane, pentane, hexane, paraffins, and isomers thereof). In some cases, the feedstock includes hydrocarbons that are solid at room temperature (e.g., polyethylene). Typically, these hydrocarbons will vaporize in the reactor. In some cases, the feedstock includes aromatic hydrocarbons (e.g., benzene or toluene).

[0022] In some cases, the feedstock contains other components, such as gases (e.g., carbon dioxide, carbon monoxide, water, or a combination thereol). Within the reactor 107, these other molecules may react, changing their relative composition within the exit stream of the reactor. For instance, the reactor can be configured to produce synthesis gas, a mixture including hydrogen and carbon monoxide, by introducing a mixture of methane and carbon dioxide.

[0023] The catalyst powder hopper 104 is configured to contain the aerosolizable catalyst powder and to inject the powder into conduit 105 going toward the reactor 107. Injection of the catalyst powder may be achieved by a variety of mechanisms. In one example, a rotating blade distributor injects the powder into the conduit 105. In another example, an eductor (e.g., using the Venturi effect) is used to draw powder from the conduit 105 through a pressure drop caused by rapidly flowing gas in inlet 102.

[0024] Aerosolized powders tend to have an attractive force between particles (e.g., electrostatic forces) that cause the powder to aggregate. In some cases, the powder in catalyst powder hopper 104 is of such a shape and density that it immediately aerosolizes upon injection into a moving gas stream. In other cases, an aerosolizer 106 is used to separate the aggregates into individual aerosolized particles. In one example, aerosolizer 106 is anAttorney Docket No.: 44807-0480W01 / JHU C18203 ultrasonic transducer that imparts a high frequency sound wave to the flow gas. In another example, a mechanical agitator is used to aerosolize the particles.

[0025] The catalyst powder typically includes one or more of carbon, iron, nickel, and cobalt, with the content of each element in a range of 0 wt.% to 100 wt.% of the catalyst powder. Although the powder is generally referred to herein as a catalyst, all elements of the powder may not function as a true catalyst (e.g.. may not lower the activation barrier for the decomposition of hydrocarbons). The catalyst powder can be a carbonaceous (e.g., carbon- containing) powder in the form of spherical particles, flakes, or aggregates. The spherical particles can be carbonaceous spheres with a surface roughness less than 100 nm. The carbonaceous powders can be flake-like with an average thickness in a range of 350 nm to 5 pm. The carbonaceous powder can include aggregates (e.g., fractal aggregates) with individual particle sizes in a range of 150 nm to 5 pm, and an aggregate size in a range of 5 pm to 50 pm. In some cases, the carbonaceous powder has surface metal particles such as Ni, Fe, Co, or alloys or mixtures thereof with average diameter less than 250 nm. A bulk density of the carbonaceous powder is typically in a range of 2.2 g / cm3to 5 g / cm3, based on pure element densities of Fe: 7.87 g / cm3(Fe), Ni: 8.9 g / cm3(Ni), and Co: 8.9 g / cm3(Co). In some cases, metal particles of Ni, Fe, Co, or alloys or mixtures thereof may be found inside the carbonaceous powder particles.

[0026] Reactor 107 provides the volume in which the chemical reaction of interest occurs (e.g.. hydrocarbon decomposition to yield hydrogen gas and solid carbon). If the feedstock contains < 20 vol% carbon dioxide, carbon monoxide, or water, the reaction product may include carbon monoxide or carbon dioxide. In some cases, the reaction product includes undecomposed or partially decomposed hydrocarbon.

[0027] Heat can be supplied to reactor 107 by a variety of methods (e.g., resistive heating, inductive heating, microwave hearing, or via a firebox burning hydrocarbons or hydrogen or a mix of both). When heat is provided by resistive heating, resistive heating elements can be positioned inside the reaction zone, outside the reaction zone, or both. When positioned in the reactor, the heat generated by the resistive heating elements can be effectively coupled to the aerosolized powder and entraining gas. Temperatures at which hydrocarbons decompose to solid carbon and hydrogen generally range from 800 °C upward, with a typical temperature range between 1000 °C and 1300 °C when resistive heating elements are used. In one example, heating elements are positioned in the reaction zone and the walls of the reactor 107 are lined with insulation in order to keep heat within the reaction zone. In some cases, the heating elements are advantageously made of heating wire that doesAttorney Docket No.: 44807-0480W01 / JHU C18203 not chemically react with hydrocarbons. That is, while there may be deposition of carbon on the heating elements, the formation of chemical carbide compounds may be avoided.

[0028] The product stream exits from the reaction zone of reactor 107 and passes through a heat exchanger 108. The product stream typically includes a mixture of two or more of the following components: catalyst (aerosolized or not), carbon deposited on the catalyst, hydrocarbons (unreacted or partially decomposed), hydrogen, carbon monoxide (e.g., if the feedstock includes carbon oxides), and solid material that may have formed during hydrocarbon deposition. The configuration of the heat exchanger 108 may be shell and tube, or a plate heat exchanger depending on the properties of the materials to be cooled. When the heat exchanger 108 is shell and tube, the product stream ty pically passes through the tube side of the heat exchanger.

[0029] Once cooled, the product stream passes into a collection hopper 109, which contains one or more filters configured to separate gaseous and solid products. Gaseous species such as hydrogen exit the reactor system in an exit stream through outlet 110, and solids exit in an exit stream through outlet 111. After leaving the collection hopper 109, some solids may be removed completely from the system in a stream through outlet 112. In some embodiments, it may be advantageous to divert at least some of the solid products back to the catalyst powder hopper 104. In this case, the diverted fraction of the products passes through conduit 113. If these products are too large to be aerosolized, they may be ground more finely with mechanical grinder 114 prior to re-introduction to the catalyst powder hopper 104 as a stream through inlet 1 15.

[0030] FIG. 2 shows an embodiment of a reactor system 200 in which the entrained aerosol powder and reactant gas is first passed through a heat exchanger before being introduced to the reactor. This configuration can improve the overall energy efficiency of the hydrocarbon decomposition process described with respect to FIG. 1.

[0031] Feedstock is provided to the reactor system through one or more of streams through one or more of inlets 201, 202, and 203. Inlet 201 provides the feedstock to a catalyst powder hopper 204. Inlet 202 provides the feedstock to the system downstream from the catalyst powder hopper 204, and inlet 203 provides the feedstock to the reactor 207.

[0032] In some cases, the feedstock consists of, consists essentially^ of, or includes gaseous hydrocarbons (e.g., methane). In some implementations, the feedstock includes heavier hydrocarbons (e.g., ethane, propane, butane, pentane, hexane, paraffins, and isomers thereof). In some cases, the feedstock includes hydrocarbons that are solid at roomAttorney Docket No.: 44807-0480W01 / JHU C18203 temperature (e.g., polyethylene). Typically, these hydrocarbons will vaporize in the reactor. In some cases, the feedstock includes aromatic hydrocarbons (e.g., benzene or toluene).

[0033] In some cases, the feedstock contains other components, such as gases (e.g., carbon dioxide, carbon monoxide, water, or a combination thereof). Within the reactor 207, these other molecules may react, changing their relative composition within the exit stream of the reactor. If the reactor is configured to produce synthesis gas, a mixture including hydrogen and carbon monoxide, this may be preferable.

[0034] The catalyst powder hopper 204 is configured to contain the aerosolizable catalyst powder and to inject the powder into conduit 205 going toward the reactor 207. Injection of the catalyst powder may be achieved by a variety of mechanisms. In one example, a rotating blade distributor injects the powder into the conduit 205. In another example, an eductor (e.g., using the Venturi effect) is used to draw powder from the conduit 205 through a pressure drop caused by rapidly flowing gas in inlet 202.

[0035] Aerosolized powders tend to have an attractive force between particles (e.g., electrostatic forces) that cause the powder to aggregate. In some cases, the powder in catalyst powder hopper 204 is of such a shape and density that it immediately aerosolizes upon injection into a moving gas stream. In other cases, an aerosolizer 206 is used to separate the aggregates into individual aerosolized particles. In one example, aerosolizer 206 is an ultrasonic transducer that imparts a high frequency sound wave to the flow gas. In another example, mechanical agitation is used to aerosolize the particles.

[0036] The catalyst powder typically includes one or more of carbon, iron, nickel, and cobalt, with the content of each element is in a range of 0 wt.% to 100 wt.%. Although the powder is generally referred to herein as a catalyst, deposition of carbon may occur on materials that do not lower the activation barrier for a chemical reaction. The catalyst powder can be a carbonaceous (e.g., carbon-containing) powder in the form of spherical particles, flakes, or aggregates. The spherical particles can be carbonaceous spheres with a surface roughness less than 100 nm. The carbonaceous pow ders can be flake-like with an average thickness in a range of 350 nm to 5 pm. The carbonaceous powder can include aggregates (e.g.. fractal aggregates) with individual particle sizes in a range of 150 nm to 5 pm, and an aggregate size in a range of 5 pm to 50 pm. In some cases, the carbonaceous powder has surface metal particles such as Ni, Fe, Co, or alloys or mixtures thereof with average diameter less than 250 nm. A bulk density of the carbonaceous pow der is typically in a range of 2.2 g / cm3to 5 g / cm3, based on pure element densities of Fe: 7.87 g / cm3(Fe). Ni: 8.9 g / cm3(Ni).Attorney Docket No.: 44807-0480W01 / JHU C18203 and Co: 8.9 g / cm3(Co). In some cases, metal particles of Ni, Fe, Co, or alloys or mixtures thereof may be found inside the carbonaceous powder particles.

[0037] When hydrocarbon gasses are heated to high temperatures (e.g., above approximately 500°C), hydrocarbon gas mixtures exhibit hot wall cracking or “fouling,” which refers to carbon deposition on nearby hot walls. Fouling is particularly problematic in heat exchangers, where it is often difficult to remove the carbon deposits, leading to increased downtime and higher operational costs. For at least this reason, the inlet stream of a hydrocarbon decomposition reactor is generally not pre-heated by heat exchange with the outlet stream.

[0038] Aerosolized catalyst powder or particles entrained in the hydrocarbon inlet stream are good heat absorbers and thus within a reaction zone of the reactor provide a surface for hydrocarbon decomposition. That is, hydrocarbon decomposition can occur on the powder surface, thereby reducing or eliminating deposition on a hot wall of a reactor or heat exchanger. Here, an aerosolized catalyst mixture allows preheating the mixture to over 500°C without the fouling the walls of a heat exchanger. Because the aerosolized catalyst mixture is fed into the hot reactor, the inlet stream can be pre-heated to nearly the reactor temperature itself (e.g., 1000 °C to 1300 °C). This relieves at least some of the burden of the reactor heating requirement, significantly increasing overall system efficiency. Reactor system efficiency improvements of over 25% can be achieved with this type of recuperative heat exchange.

[0039] Using recuperative heat exchange, the mixture of aerosolized powder and gas passes through the heat exchanger 208 before entering the reactor 207 through conduit 216. Reactor 207 provides the volume in which the chemical reaction of interest occurs, primarily hydrocarbon decomposition to yield hydrogen gas and solid carbon. If the input gas contains < 20 vol% carbon dioxide, carbon monoxide, or water, some fraction of the reaction product may contain carbon monoxide or carbon dioxide. In some cases, the reaction product includes undecomposed or partially decomposed hydrocarbon.

[0040] Heat can be supplied to reactor 207 by a variety of methods (e.g., resistive heating, inductive heating, microwave hearing, or via a firebox burning hydrocarbons or hydrogen or a mix of both). When heat is provided by resistive heating, resistive heating elements can be positioned inside the reaction zone, outside the reaction zone, or both. When positioned in the reactor, the heat generated by the resistive heating elements can be effectively coupled to the aerosolized powder and entraining gas. Temperatures at which hydrocarbons decompose to solid carbon and hydrogen generally range from 800 °C upward.Attorney Docket No.: 44807-0480W01 / JHU C18203 with a typical temperature range between 1000 °C and 1300 °C when resistive heating elements are used. In one example, heating elements are positioned in the reaction zone and the walls of the reactor 207 are lined with insulation in order to keep heat within the reaction zone. In some cases, the heating elements are advantageously made of heating wire that does not chemically react with hydrocarbons. That is, while there may be deposition of carbon on the heating elements, the formation of chemical carbide compounds may be avoided.

[0041] The product stream exits from the reaction zone of reactor 207 and passes through a heat exchanger 208. The product stream typically includes a mixture of two or more of the following components: catalyst (aerosolized or not), carbon deposited on the catalyst, hydrocarbons (unreacted or partially decomposed), hydrogen, carbon monoxide (e.g., if the feedstock includes carbon oxides), and solid material that may have formed during hydrocarbon deposition. The configuration of the heat exchanger 208 may be shell and tube, or a plate heat exchanger depending on the properties of the materials to be cooled. When the heat exchanger 208 is shell and tube, the product stream ty pically passes through the tube side of the heat exchanger.

[0042] Once cooled, the product stream passes into a collection hopper 209, which contains one or more filters configured to separate gaseous and solid products. Gaseous species such as hydrogen exit the reactor system in an exit stream through outlet 210, and solids exit in an exit stream through outlet 211. After leaving the collection hopper 209, some solids may be removed completely from the system in a stream through outlet 212. In some embodiments, it may be advantageous to divert at least some of the solid products back to the catalyst powder hopper 204. In this case, the diverted fraction of the products passes through conduit 213. If these products are too large to be aerosolized, they may be ground more finely with mechanical grinder 214 prior to re-introduction to the catalyst powder hopper 204 as a stream through inlet 215.

[0043] FIG. 3 shows a schematic of the reactor in which the heating elements 302 in configuration (a) are inside the reactor vessel 301. In configuration (b), heating elements 302 are outside the reactor vessel 301 and, at times, embedded into insulation 303.

[0044] FIG. 4 shows a schematic of various heating options available for the reactor 401. In configuration (a), the first zone is heated by a microwave system 402, and the second zone is heated by resistive heaters 403. Alternatively, the entire reactor, i.e., 401, could be heated by radiative elements 404 or by radiative tubes 405 that circulate either hot sand or molten salt.Attorney Docket No.: 44807-0480W01 / JHU C18203

[0045] FIG. 5 shows a schematic of reactor 501, which comprises a pre-heat zone 502, a reaction zone 503, and an adiabatic zone 504. Tunable amounts of heating power are supplied to each zone as needed.

[0046] FIG. 6 shows a view of the process wherein the catalyst and gas react in reactor 601, then cool through heat exchanger 602. Finally, the gas and solids that contain the catalyst are separated by filter 603. In the depicted configuration, a portion of the separated solids 604 is recirculated in the system by passing through a mechanical mill 605 before injecting into reactor 601 via the recirculation line 606.

[0047] FIG. 7 shows a schematic of the powder injector system 701 in the aerosol chamber 702, which could be a spray dryer, eductor, or Venturi powder sprayer that can operate either as a continuous injector or a pulsed injector generating the aerosol 703.

[0048] FIG. 8 is a schematic where aerosol chamber 801, in configuration (a), generates the aerosol with an internal ultrasonic horn 802, and in (b), an external ultrasonic horn 803 is used to aerosolize powders.

[0049] FIG. 9 is a schematic of aerosol chamber 901 in configuration (a), which uses an electrostatic field generator 902 to generate the aerosol. In configuration (b). powders are aerosolized by impacting them onto a deflection surface 903. The deflection surface is angled (e.g., between 10° and 75°) to the direction of a flow of the aerosolized reaction mixture.

[0050] FIG. 10 is a schematic of aerosol chamber 1001 in configuration (a), powder aerosolization is achieved by impacting the powder mixture onto a deflection surface of an upright cone 1002. In some examples, the upright cone has a cone angle >20° and < 160°. In configuration (b), the deflection surface is an inverted cone 1003. In some examples, the inverted cone has a cone angle >20° and < 120°.

[0051] Reducing build-up of carbonaceous deposits on a wall of a heat exchanger can include combining a particulate catalyst with a gaseous feedstock stream comprising a gaseous hydrocarbon to yield an aerosolized reaction mixture, flowing the aerosolized reaction mixture through the heat exchanger, thereby heating the aerosolized reaction mixture, decomposing the gaseous hydrocarbon to yield elemental carbon and hydrogen gas. and depositing the elemental carbon on the particulate catalyst. This can be achieved by any combination of any components described herein with respect to various reactor systems.

[0052] Although this disclosure contains many specific embodiment details, these should not be construed as limitations on the scope of the subject matter or on the scope of what maybe claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in this disclosure in the context of separateAttorney Docket No.: 44807-0480W01 / JHU C18203 embodiments can also be implemented, in combination, in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments, separately, or in any suitable sub-combination. Moreover, although previously described features may be described as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can, in some cases, be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

[0053] Although the disclosed inventive concepts include those defined in the attached claims, it should be understood that the inventive concepts can also be defined in accordance with the following embodiments.

[0054] Embodiment 1 is a method of producing hydrogen gas, the method comprising: combining a gaseous feedstock stream with a particulate catalyst, wherein the gaseous feedstock stream comprises a gaseous hydrocarbon, and the particulate catalyst is selected to promote decomposition of the gaseous hydrocarbon; entraining the particulate catalyst in the gaseous feedstock stream to yield an aerosolized reaction mixture comprising aerosolized catalyst particles; and heating the aerosolized reaction mixture to decompose the gaseous hydrocarbon, thereby yielding a product stream comprising elemental carbon and hydrogen gas.

[0055] Embodiment 2 is the method of embodiment 1, wherein the gaseous feedstock stream further comprises carbon dioxide.

[0056] Embodiment 3 is the method of embodiment 1 or 2, wherein the gaseous feedstock stream further comprises hydrogen gas.

[0057] Embodiment 4 is the method of any one of embodiments 1-3, wherein a flow rate of the gaseous feedstock stream is in a range of 1 slpm to 100,000 slpm.

[0058] Embodiment 5 is the method of any one of embodiments 1-4, wherein the particulate catalyst comprises carbon, iron, nickel, cobalt, or any alloy or mixture thereof.

[0059] Embodiment 6 is the method of any one of embodiments 1-5, wherein the gaseous hydrocarbon comprises methane.

[0060] Embodiment 7 is the method of any one of embodiments 1-6. wherein the gaseous hydrocarbon comprises an alkane or alkene with 2-10 carbon atoms.

[0061] Embodiment 8 is the method of any one of embodiments 1-7, wherein the gaseous hydrocarbon comprises an alkane or alkene with 2-10 carbon atoms.

[0062] Embodiment 9 is the method of any one of embodiments 1-8, wherein the gaseous hydrocarbon comprises a vaporized polymer.Attorney Docket No.: 44807-0480W01 / JHU C18203

[0063] Embodiment 10 is the method of embodiment 9, wherein the vaporized polymer comprises polyethylene.

[0064] Embodiment 11 is the method of any one of embodiments 1-10, wherein the product stream further comprises one or more oxides of carbon.

[0065] Embodiment 12 is the method of any one of embodiments 1-11, wherein the product stream further comprises some of the aerosolized catalyst particles from the aerosolized reaction mixture.

[0066] Embodiment 13 is the method of any one of embodiments 1-12, wherein combining the gaseous feedstock stream with the particulate catalyst comprises injecting the particulate catalyst into the gaseous feedstock stream.

[0067] Embodiment 14 is the method of any one of embodiments 1-13. further comprising heating the gaseous feedstock stream, the particulate catalyst, or both before combining the gaseous feedstock stream and the particulate catalyst.

[0068] Embodiment 15 is the method of any one of embodiments 1-14, further comprising dispersing the particulate catalyst in an aerosol chamber before combining the gaseous feedstock stream and the particulate catalyst.

[0069] Embodiment 16 is the method of any one of embodiments 1-15, wherein combining the gaseous feedstock stream with the particulate catalyst comprises injecting the particulate catalyst into the gaseous feedstock stream.

[0070] Embodiment 17 is the method of embodiment 16, further comprising dry spraying the particulate catalyst in an aerosol chamber before injecting the particulate catalyst into the gaseous feedstock stream.

[0071] Embodiment 18 is the method of embodiment 17, wherein the dry spraying is pulsed.

[0072] Embodiment 19 is the method of any one of embodiments 1-18, wherein combining the gaseous feedstock stream with the particulate catalyst comprises drawing, with the Venturi effect, the particulate catalyst into a stream comprising the gaseous feedstock stream.

[0073] Embodiment 20 is the method of any one of embodiments 1-19. wherein heating the aerosolized reaction mixture occurs in two or more heating stages.

[0074] Embodiment 21 is the method of any one of embodiments 1-20, wherein heating the aerosolized reaction mixture comprises heating in a range of 800 - 1500 °C.Attorney Docket No.: 44807-0480W01 / JHU C18203

[0075] Embodiment 22 is the method of any one of embodiments 1-21, wherein heating the aerosolized reaction mixture comprises resistive heating, inductive heating, heating via combustion, or heating with microwave radiation.

[0076] Embodiment 23 is the method of any one of embodiments 1-22, wherein heating the aerosolized reaction mixture occurs at a pressure in a range of 0.1-100 bar or 5-10 bar.

[0077] Embodiment 24 is the method of any one of embodiments 1-23. further comprising cooling the product stream to yield a cooled product stream.

[0078] Embodiment 25 is the method of any one of embodiments 1-24, further comprising separating gases and solid material in the cooled product stream.

[0079] Embodiment 26 is the method of any one of embodiments 1-25. further comprising combining some of the solid material in the product stream with the particulate catalyst to be combined with the gaseous feedstock stream.

[0080] Embodiment 27 is the method of any one of embodiments 1-26, further comprising reducing a size of the solid material before combining with the particulate catalyst.

[0081] Embodiment 28 is a reactor system for decomposition of hydrocarbons, the reactor system comprising: a reactor configured to receive an aerosolized reaction mixture comprising a gaseous feedstock stream and a particulate catalyst, wherein the gaseous feedstock stream comprises a gaseous hydrocarbon and the particulate catalyst is selected to promote decomposition of the gaseous hydrocarbon into a product stream comprising elemental carbon and hydrogen gas; a heater coupled to the reactor and configured to heat an interior of the reactor; a first inlet configured to provide the gaseous feedstock stream to the reactor; a vessel configured to contain the particulate catalyst and combine the particulate catalyst with the gaseous feedstock stream; a heat exchanger configured to receive the product stream from the reactor; a separator configured to receive a cooled product stream from the heat exchanger and to separate solid material and gas in the cooled product stream; a first outlet configured to allow removal of the solid material from the separator; and a second outlet configured to allow removal of the gas from the separator.

[0082] Embodiment 29 is the reactor system of embodiment 28, wherein the reactor is configured to operate in a pressure range of 0. 1-100 bar or 5-10 bar.

[0083] Embodiment 30 is the reactor system of embodiment 28 or 29, wherein the heater is configured to heat the interior of the reactor to a temperature in a range of 800 - 1500 °C.Attorney Docket No.: 44807-0480W01 / JHU C18203

[0084] Embodiment 31 is the reactor system of any one of embodiments 28-30, wherein the heater comprises resistive heating elements inside a reaction zone, outside a reaction zone, or both of the reactor.

[0085] Embodiment 32 is the reactor system of any one of embodiments 28-31, wherein the heater is configured to provide microwave radiation to the interior of the reactor.

[0086] Embodiment 33 is the reactor system of any one of embodiments 28-32, wherein the heater comprises heating elements encased in ceramic.

[0087] Embodiment 34 is the reactor system of any one of embodiments 28-33, wherein the heater comprises heating elements that are inert to carbon-containing gases.

[0088] Embodiment 35 is the reactor system of any one of embodiments 28-34, wherein the heater comprises radiative elements configured to contain heating elements, hot sand, or molten salt heat transfer fluid inside the reactor.

[0089] Embodiment 36 is the reactor system of any one of embodiments 28-35, wherein the heater comprises a first chamber configured to heat the aerosolized reaction mixture with microwave radiation and a second chamber configured to heat the aerosolized reaction mixture with resistive heating elements.

[0090] Embodiment 37 is the reactor system of embodiment 36, wherein the heater further comprises one or more additional heating chambers.

[0091] Embodiment 38 is the reactor system of any one of embodiments 28-37, further comprising a first in-line heater upstream of the reactor and configured to heat the gaseous feedstock stream and a second in-line heater upstream of the reactor and configured to heat the particulate catalyst.

[0092] Embodiment 39 is the reactor system of embodiment 38, further comprising an adiabatic zone configured to receive the gaseous feedstock stream downstream of the first inline heater and the particulate catalyst downstream from the second in-line heater.

[0093] Embodiment 40 is the reactor system of any one of embodiments 28-39, further comprising a recycling loop configured to provide some of the solid material to the vessel.

[0094] Embodiment 41 is the reactor system of any one of embodiments 28-40, further comprising a mechanical mill configured to reduce a particle size of the particulate catalyst.

[0095] Embodiment 42 is the reactor system of any one of embodiments 28-41, further comprising an ultrasonic transducer coupled to the vessel and configured to aerosolize the particulate catalyst upstream of the reactor.Attorney Docket No.: 44807-0480W01 / JHU C18203

[0096] Embodiment 43 is the reactor system of any one of embodiments 28-42, further comprising a device configured to generate an electrostatic field in an aerosol chamber to disperse the particulate catalyst upstream of the reactor.

[0097] Embodiment 44 is the reactor system of any one of embodiments 28-43, further comprising an ultrasonic hom configured to aerosolize the particulate catalyst upstream of the reactor.

[0098] Embodiment 45 is the reactor system of any one of embodiments 28-44, further comprising an ultrasonic hom configured to aerosolize the aerosolized reaction mixture.

[0099] Embodiment 46 is the reactor system of embodiment 45, wherein the ultrasonic hom is positioned externally to a conduit earn ing the aerosolized reaction mixture.

[0100] Embodiment 47 is the reactor system of any one of embodiments 28-46, further comprising a powder sprayer coupled to the vessel and configured to draw the particulate catalyst from the vessel and combine the particulate catalyst with the gaseous feedstock stream.

[0101] Embodiment 48 is the reactor system of embodiment 47, wherein the particulate catalyst is drawn from the vessel via the Venturi effect.

[0102] Embodiment 49 is the reactor system of any one of embodiments 28-48, further comprising a sprayer coupled to the vessel and configured to spray the particulate catalyst in an aerosol chamber upstream of the reactor.

[0103] Embodiment 50 is the reactor system of embodiment 49, wherein the sprayer is configured to spray the particulate catalyst in a pulsed manner.

[0104] Embodiment 51 is the reactor system of embodiment 49, wherein the sprayer comprises an eductor.

[0105] Embodiment 52 is the reactor system of any one of embodiments 28-51, further comprising a sprayer configured to dry spray the particulate catalyst into the reactor.

[0106] Embodiment 53 is the reactor system of embodiment 49, wherein the sprayer is configured to dry spray the particulate catalyst in a pulsed manner.

[0107] Embodiment 54 is the reactor system of embodiment 49, wherein the sprayer comprises an eductor.

[0108] Embodiment 55 is the reactor system of any one of embodiments 28-54, further comprising a deflection surface configured to disperse the particulate catalyst in the reactor by aerosolized reaction mixture.

[0109] Embodiment 56 is the reactor system of embodiment 55, wherein the deflection surface comprises a flat plate perpendicular to a flow of the aerosolized reaction mixture.Attorney Docket No.: 44807-0480W01 / JHU C18203

[0110] Embodiment 57 is the reactor system of embodiment 55, wherein the deflection surface is angled (e.g., between 10° to 75°) to the direction of a flow of the aerosolized reaction mixture.

[0111] Embodiment 58 is the reactor system of embodiment 55, wherein the deflection surface comprises an upright cone (e.g., cone angle >20° and < 160°).

[0112] Embodiment 59 is the reactor system of embodiment 55, wherein the deflection surface is an inverted cone (e.g.. cone angle >20° and < 120°).

[0113] Embodiment 60 is a method of reducing build-up of carbonaceous deposits on a wall of a heat exchanger, the method comprising: combining a particulate catalyst with a gaseous feedstock stream comprising a gaseous hydrocarbon to yield an aerosolized reaction mixture; flowing the aerosolized reaction mixture through the heat exchanger, thereby heating the aerosolized reaction mixture; decomposing the gaseous hydrocarbon to yield elemental carbon and hydrogen gas; and depositing the elemental carbon on the particulate catalyst.

[0114] Particular embodiments of the subject matter have been described. Other embodiments, alterations, and permutations of the described embodiments are within the scope of the following claims as will be apparent to those skilled in the art. While operations are depicted in the drawings or claims in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed (some operations may be considered optional), to achieve desirable results.

[0115] Accordingly, the previously described example embodiments do not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure.

Claims

Attorney Docket No.: 44807-0480W01 / JHU C18203WHAT IS CLAIMED IS:

1. A method of producing hydrogen gas, the method comprising: combining a gaseous feedstock stream with a particulate catalyst, wherein the gaseous feedstock stream comprises a gaseous hydrocarbon, and the particulate catalyst is selected to promote decomposition of the gaseous hydrocarbon; entraining the particulate catalyst in the gaseous feedstock stream to yield an aerosolized reaction mixture comprising aerosolized catalyst particles; and heating the aerosolized reaction mixture to decompose the gaseous hydrocarbon, thereby yielding a product stream comprising elemental carbon and hydrogen gas.

2. The method of claim 1, wherein the gaseous feedstock stream further comprises carbon dioxide.

3. The method of claim 1, wherein the gaseous feedstock stream further comprises hydrogen gas.

4. The method of claim 1, wherein a flow rate of the gaseous feedstock stream is in a range of 1 slpm to 100,000 slpm.

5. The method of claim 1 , wherein the particulate catalyst comprises carbon, iron, nickel, cobalt, or any alloy or mixture thereof.

6. The method of claim 1, wherein the gaseous hydrocarbon comprises methane.

7. The method of claim 1, wherein the gaseous hydrocarbon comprises an alkane or alkene with 2-10 carbon atoms.

8. The method of claim 1, wherein the gaseous hydrocarbon comprises an aromatic hydrocarbon.

9. The method of claim 1 , wherein the gaseous hydrocarbon comprises a vaporized polymer.Attorney Docket No.: 44807-0480W01 / JHU C1820310. The method of claim 9, wherein the vaporized polymer comprises polyethylene.

11. The method of claim 1, wherein the product stream further comprises one or more oxides of carbon.

12. The method of claim 1, wherein the product stream further comprises some of the aerosolized catalyst particles from the aerosolized reaction mixture.

13. The method of claim 1, wherein combining the gaseous feedstock stream with the particulate catalyst comprises injecting the particulate catalyst into the gaseous feedstock stream.

14. The method of claim 1, further comprising heating the gaseous feedstock stream, the particulate catalyst, or both before combining the gaseous feedstock stream and the particulate catalyst.

15. The method of claim 1, further comprising dispersing the particulate catalyst in an aerosol chamber before combining the gaseous feedstock stream and the particulate catalyst.

16. The method of claim 1, wherein combining the gaseous feedstock stream with the particulate catalyst comprises injecting the particulate catalyst into the gaseous feedstock stream.

17. The method of claim 16, further comprising dry spraying the particulate catalyst in an aerosol chamber before injecting the particulate catalyst into the gaseous feedstock stream.

18. The method of claim 17, wherein the dry spraying is pulsed.

19. The method of claim 1, wherein combining the gaseous feedstock stream with the particulate catalyst comprises drawing, with the Venturi effect, the particulate catalyst into a stream comprising the gaseous feedstock stream.

20. The method of claim 1, wherein heating the aerosolized reaction mixture occurs in two or more heating stages.Attorney Docket No.: 44807-0480W01 / JHU C1820321. The method of claim 1, wherein heating the aerosolized reaction mixture comprises heating in a range of 800 - 1500 °C.

22. The method of claim 1, wherein heating the aerosolized reaction mixture comprises resistive heating, inductive heating, heating via combustion, or heating with microwave radiation.

23. The method of claim 1, wherein heating the aerosolized reaction mixture occurs at a pressure in a range of 0.1-100 bar or 5-10 bar.

24. The method of claim 1 , further comprising cooling the product stream to yield a cooled product stream.

25. The method of claim 24, further comprising separating gases and solid material in the cooled product stream.

26. The method of claim 25, further comprising combining some of the solid material in the product stream with the particulate catalyst to be combined with the gaseous feedstock stream.

27. The method of claim 26, further comprising reducing a size of the solid material before combining with the particulate catalyst.

28. A reactor system for decomposition of hydrocarbons, the reactor system comprising: a reactor configured to receive an aerosolized reaction mixture comprising a gaseous feedstock stream and a particulate catalyst, wherein the gaseous feedstock stream comprises a gaseous hydrocarbon and the particulate catalyst is selected to promote decomposition of the gaseous hydrocarbon into a product stream comprising elemental carbon and hydrogen gas; a heater coupled to the reactor and configured to heat an interior of the reactor; a first inlet configured to provide the gaseous feedstock stream to the reactor;Attorney Docket No.: 44807-0480W01 / JHU C18203 a vessel configured to contain the particulate catalyst and combine the particulate catalyst with the gaseous feedstock stream; a heat exchanger configured to receive the product stream from the reactor; a separator configured to receive a cooled product stream from the heat exchanger and to separate solid material and gas in the cooled product stream; a first outlet configured to allow removal of the solid material from the separator; and a second outlet configured to allow removal of the gas from the separator.

29. The reactor system of claim 28, wherein the reactor is configured to operate in a pressure range of 0.1-100 bar or 5-10 bar.

30. The reactor system of claim 28, wherein the heater is configured to heat the interior of the reactor to a temperature in a range of 800 - 1500 °C.

31. The reactor system of claim 28, wherein the heater comprises resistive heating elements inside a reactor zone, outside a reaction one. or both of the reactor.

32. The reactor system of claim 28, wherein the heater is configured to provide microwave radiation to the interior of the reactor.

33. The reactor system of claim 28, wherein the heater comprises heating elements encased in ceramic.

34. The reactor system of claim 28, wherein the heater comprises heating elements that are inert to carbon-containing gases.

35. The reactor system of claim 28, wherein the heater comprises radiative elements configured to contain heating elements, hot sand, or molten salt heat transfer fluid inside the reactor.

36. The reactor system of claim 28, wherein the heater comprises a first chamber configured to heat the aerosolized reaction mixture with microwave radiation and a second chamber configured to heat the aerosolized reaction mixture with resistive heating elements.Attorney Docket No.: 44807-0480W01 / JHU C1820337. The reactor system of claim 36, wherein the heater further comprises one or more additional heating chambers.

38. The reactor system of claim 28, further comprising a first in-line heater upstream of the reactor and configured to heat the gaseous feedstock stream and a second in-line heater upstream of the reactor and configured to heat the particulate catalyst.

39. The reactor system of claim 38, further comprising an adiabatic zone configured to receive the gaseous feedstock stream down stream of the first in-line heater and the particulate catalyst downstream from the second in-line heater.

40. The reactor system of claim 28, further comprising a recycling loop configured to provide some of the solid material to the vessel.

41. The reactor system of claim 28, further comprising a mechanical mill configured to reduce a particle size of the particulate catalyst.

42. The reactor system of claim 28, further comprising an ultrasonic transducer coupled to the vessel and configured to aerosolize the particulate catalyst upstream of the reactor.

43. The reactor system of claim 28, further comprising a device configured to generate an electrostatic field in an aerosol chamber to disperse the particulate catalyst upstream of the reactor.

44. The reactor system of claim 28, further comprising an ultrasonic horn configured to aerosolize the particulate catalyst upstream of the reactor.

45. The reactor system of claim 28, further comprising an ultrasonic hom configured to aerosolize the aerosolized reaction mixture.

46. The reactor system of claim 45, wherein the ultrasonic hom is positioned externally to a conduit carrying the aerosolized reaction mixture.Attorney Docket No.: 44807-0480W01 / JHU C1820347. The reactor system of claim 28, further comprising a powder sprayer coupled to the vessel and configured to draw the particulate catalyst from the vessel and combine the particulate catalyst with the gaseous feedstock stream.

48. The reactor system of claim 47, wherein the particulate catalyst is drawn from the vessel via the Venturi effect.

49. The reactor system of claim 28, further comprising a sprayer coupled to the vessel and configured to spray the particulate catalyst in an aerosol chamber upstream of the reactor.

50. The reactor system of claim 49, wherein the sprayer is configured to spray the particulate catalyst in a pulsed manner.

51. The reactor system of claim 49, wherein the sprayer comprises an eductor.

52. The reactor system of claim 28, further comprising a sprayer configured to dry spray the particulate catalyst into the reactor.

53. The reactor system of claim 52, wherein the sprayer is configured to dry spray the particulate catalyst in a pulsed manner.

54. The reactor system of claim 52, wherein the sprayer comprises an eductor.

55. The reactor system of claim 28, further comprising a deflection surface configured to disperse the particulate catalyst in the reactor by aerosolized reaction mixture.

56. The reactor system of claim 55, wherein the deflection surface comprises a flat plate perpendicular to a flow of the aerosolized reaction mixture.

57. The reactor system of claim 55, wherein the deflection surface is angled between 10° and 75° relative to the direction of a flow of the aerosolized reaction mixture.

58. The reactor system of claim 55, wherein the deflection surface comprises an upright cone having a cone angle >20° and < 160°.Attorney Docket No.: 44807-0480W01 / JHU C1820359. The reactor system of claim 55, wherein the deflection surface is an inverted cone having a cone angle >20° and < 120°.

60. A method of reducing build-up of carbonaceous deposits on a wall of a heat exchanger, the method comprising: combining a particulate catalyst with a gaseous feedstock stream comprising a gaseous hydrocarbon to yield an aerosolized reaction mixture; flowing the aerosolized reaction mixture through the heat exchanger, thereby heating the aerosolized reaction mixture; decomposing the gaseous hydrocarbon to yield elemental carbon and hydrogen gas; and depositing the elemental carbon on the particulate catalyst.

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