Molten salt reactor system for methane pyrolysis

Abstract

A reactor system active for thermally decomposing methane under effective conditions, comprising a molten salt medium and a reaction vessel, wherein the molten salt is contained within the reaction vessel using various methods of catalyst distribution within the vessel such that as methane passes through the vessel, it contacts a catalyst that causes a thermal decomposition reaction, thereby reducing carbon dioxide emissions and producing molecular hydrogen. The catalyst may be disposed within the reaction vessel either as suspended particles or in a structured packing form.

Description

[Technical Field]

[0001] The present invention relates to a reactor system and related processes for carrying out a chemical reaction, the system comprising at least one reactor containing a catalyst. More specifically, the present invention relates to methane pyrolysis by a molten salt reactor system. [Background technology]

[0002] The reforming of methane, light hydrocarbons, or coal is a common process for producing hydrogen on a large scale. While such methods are highly optimized and well-understood in the industry, they are associated with the production of carbon dioxide. Alternatively, the pyrolysis of methane or light hydrocarbons is another approach to hydrogen production and may result in reduced carbon dioxide emissions compared to conventional methods of methane reforming. In the pyrolysis process, hydrocarbon molecules are converted to gaseous hydrogen and solid carbon via an endothermic reaction without forming carbon dioxide as a reaction product. Major challenges in the methane pyrolysis process include coke accumulation in undesirable parts of the reactor and heat input in the reaction zone. Novel and efficient solutions are needed to facilitate methane pyrolysis.

[0003] Molten salts are well-known media for carrying out endothermic reactions, such as the decomposition of hydrocarbons at high temperatures. See U.S. Patent No. 3,210,268. The thermal decomposition of methane or natural gas into carbon and hydrogen is particularly well-suited to molten salt reactors. In such reactors, the molten salt liquid acts as a heat transfer medium while preventing the accumulation of carbon species on undesirable parts of the reactor, such as the internal walls and elements. In the absence of molten salt, coke deposits must be removed periodically by other means, such as oxidation of carbon by exposure to vapor or air. Such practices generate further carbon dioxide emissions, thereby undermining one of the main driving forces behind the use of methane thermal decomposition. The thermal decomposition process of natural gas produces hydrogen with reduced carbon dioxide emissions compared to hydrocarbon reforming or coal gasification. See "Financial and Ecological Evaluation of Hydrogen Production Processes on Large Scale," Otto Machhammer et al., Chem.Eng.Technol.39, No.6, 1185-93 (2016).

[0004] According to known reactor systems, mixtures of halide salts and chlorides, specifically alkali metal and alkaline earth metal chlorides (e.g., sodium chloride, potassium chloride), can function as heat transfer fluids in high-temperature reactions (600-1000°C) while remaining chemically stable at high temperatures for reactions with natural gas feedstocks and pyrolysis products. According to these known systems, catalytic activity for methane activation is limited to alkali chloride salts, thereby requiring high reaction temperatures (T>900°C) to reach the desired methane conversion level. See "Catalytic Methane Pyrolysis in Molten MnCl2-KCl," Dohyung Kang et al., Applied Catalysis B:Environmental, Volume 254, 659-666 (2019). Achieving high methane conversion at temperatures below 1000°C increases the overall energy efficiency of the process and mitigates the material-related challenges typically present in high-temperature processes. The dispersion of catalyst materials (metal particles and / or supported metal particles) in molten salt can promote methane decomposition at lower temperatures while allowing control of the solid carbon form. See International Patent Application No. 2019 / 197256(A1). Thus, molten salt-based catalyst systems can combine the heat transfer and antifouling advantages of simple molten salts or salt mixtures (e.g., sodium chloride, or a mixture of sodium chloride and potassium chloride) with the improved activity of solid catalysts.

[0005] Known design options based on bubble column reactors are already available when the product is in liquid or gaseous form. For example, current designs of packed bubble column reactors and slurry bubble column reactors are limited to cases where the product is in liquid or gaseous form.

[0006] In conventional packed bubble reactors, catalyst particles are typically within a millimeter size range and are confined to a portion of the reactor in a fixed position. Such systems are at risk of clogging due to generated carbon particles trapped in the spaces between catalyst particles. Over time, the catalyst particle layer behaves like a deep filter, and carbon particles formed during methane pyrolysis accumulate in the voids between catalyst particles.

[0007] Another type of conventional reactor for handling multiphase reaction systems is the slurry bubble reactor. In a slurry bubble reactor, typically, catalyst particles within a smaller size range, such as 100 microns, are circulated in the liquid to prevent carbon particles from clogging the reactor. For example, the system described in International Patent Application No. 2019 / 197256(A1) includes a reactor containing a molten salt medium in which one or more catalytically active metals having particle sizes varying from 1 nm to 0.5 mm, more preferably from 1 nm to 15 nm, are dispersed. However, such a design makes the separation of the catalyst from the carbon particles particularly difficult because both the carbon product particles and the solid catalyst particles are mixed in the reactor. Furthermore, solid catalyst particles within the nanoscale range tend to form aggregates, thereby resulting in insufficient contact with the reaction gas and loss of catalyst surface area.

[0008] Due to the solid nature of the carbon products, a new reactor concept is required in the methane pyrolysis process. [Overview of the project]

[0009] A novel molten salt reactor system for the pyrolysis process of methane or natural gas has been shown to reduce carbon dioxide emissions and produce hydrogen molecules. During the pyrolysis reaction, the novel reactor, which houses the molten salt catalyst system, includes four distinct phases: methane or natural gas as feedstock and gaseous products from the reaction, liquid molten salt, solid catalyst, and solid carbon products. The reactor design is crucial for proper control of all four phases. The reactor and process conditions enable improved gas-solid catalyst contact with an appropriate ratio between gas mass and bubble surface area for heat transfer. Carbon products are continuously removed from the reactor with minimal loss of the liquid phase and solid catalyst.

[0010] In some embodiments, the process for methane pyrolysis in a molten salt medium includes exposing methane gas to a molten salt medium and a solid catalyst within the volume of a reaction vessel under conditions effective in converting at least a portion of the methane to hydrogen and solid carbon, and removing at least a portion of the solid carbon. The molten salt medium may specifically include halide salts and chloride salts. The solid catalyst may be placed in the reaction vessel either as suspended particles in the molten salt medium or in a structured packing form.

[0011] In some embodiments, a reactor system for carrying out a chemical reaction comprises one or more hydrocarbon supply lines supplied to one or more reactor sections containing a molten salt and a solid catalyst, wherein the solid catalyst is disposed in the reactor either as suspended particles in the molten salt or in a structured packing form, and the one or more reactor sections comprises a lower part of a reaction vessel and an upper part of a reaction vessel.

[0012] In some embodiments, the reactor system described herein further includes suspended catalyst particles confined to the bottom of the reaction vessel so that the catalyst particles can move freely within the bottom of the reaction vessel. In some embodiments, the reactor is configured to carry out a pyrolysis reaction resulting in the production of solid carbon particles by foaming a hydrocarbon feed through a molten salt so that hydrocarbon bubbles come into contact with the suspended catalyst particles. In some embodiments, the reactor is further configured to allow the solid carbon particles produced by the pyrolysis reaction to move upward with the movement of bubbles and the flow of molten salt to accumulate in a carbon-rich layer located at the top of the reaction vessel.

[0013] In some embodiments, the reactor system described herein has a capacity of approximately 1,500 kg / m³ 3 ~Approx. 3,800kg / m 3 Catalyst particles having a density of are included at the bottom of the reaction vessel. In other embodiments, the catalyst density is approximately 2,000 kg / m³. 3 ~Approx. 2,500kg / m 3 In some embodiments, the catalyst particles have an average size of approximately 0.6 mm to 6 mm in diameter. In some embodiments, the flow rate of the hydrocarbon supply is approximately 0.7 kg / m³. 2 / min ~ approx. 20kg / m 2 It is per minute.

[0014] In some embodiments, the reactor system described herein further comprises a pump located outside the reaction vessel, which circulates the molten salt to and from a storage tank fluidly connected to the reaction vessel, and the pump drives the circulation of the molten salt and controls the flow rate of the molten salt circulation. In some embodiments, the flow rate of the molten salt circulation is approximately 5 kg / m³ 2 / sec ~ approx. 130kg / m 2 It is per second.

[0015] In some embodiments, the reactor system described herein, in combination, facilitates a pyrolysis reaction, thereby producing solid carbon particles, and further has a methane feed flow rate and a molten salt flow rate that result in bubbles that facilitate the separation of the carbon particles produced from the suspended catalyst as the bubbles move from the lower part of the reaction vessel to the upper part of the reactor.

[0016] In some embodiments, the reactor system described herein includes a solid catalyst disposed within the reaction vessel in a structured packing form, and the structured packing form has a void volume of from about 90% to about 99%.

[0017] In some embodiments, the heterogeneous reactor comprises a vessel that includes a reaction zone, a separation zone, and a gas stripping zone. The input of the feed gas is in fluid connection with the reaction zone, and the reaction zone is in fluid connection with the separation zone. In some embodiments, the reactor described herein further includes a carbon-rich layer positioned between the separation zone and the gas stripping zone. In some embodiments, the reaction zone includes a molten salt medium and a suspended catalyst and is further configured to enable a pyrolysis reaction to occur within the reaction zone. In some embodiments, a portion of the output product from the pyrolysis reaction is in the gas phase and a portion of the output product is in the slurry phase. The gas portion of the output product passes through a demister to remove molten salt droplets and exits the vessel via a primary outlet connection. In some embodiments, the carbon-rich layer is positioned above the separation zone and includes a flow of molten salt medium and carbon that exits the vessel via a secondary outlet connection.

[0018] In some embodiments, the reactor system disclosed herein further comprises a molten salt storage tank in fluid connection with a drain pump tank, the drain pump tank being in fluid connection with the reactor and configured to pump the material within the drain pump tank into the reactor.

[0019] In some embodiments, a process for reacting a gaseous mixed reactant in a molten salt reactor system that forms a hydrogen-containing product includes at least one hydrocarbon, and the process includes passing the gaseous mixed reactant through at least one reaction vessel containing a molten salt in which a catalyst is suspended; contacting the gaseous mixed reactant with the suspended catalyst as the gaseous mixed reactant rises through the at least one reaction vessel, thereby producing an output product containing at least hydrogen and carbon via pyrolysis; and separating the output product to produce at least a concentrated carbon stream and a hydrogen stream containing at least 95 wt% hydrogen. In some embodiments, the gaseous mixed reactant can be blended with renewable natural gas.

[0020] In some embodiments, the reactor includes a vessel containing a structured packed catalyst and an input of feed gas fluidly connected to the vessel through a gas sparger, and the structured packed catalyst further includes a catalyst surface. In some embodiments, the sparger is configured to generate bubbles of feed gas that are substantially uniformly distributed across the cross-section of the vessel. In some embodiments, the vessel is configured to circulate the feed gas through the structured packed catalyst, thereby causing a pyrolysis reaction to occur when the feed gas contacts the catalyst, thereby producing an output product containing at least hydrogen and carbon. In some embodiments, the structured packed catalyst has a void volume of about 90% to about 99% or about 97% to about 99%. In some embodiments, the feed gas flow per unit cross-sectional area per unit time is from about 1 kg / m 2 / min to about 25 kg / m 2 / min, or can be in the range of about 5 kg / m 2 / min to about 15 kg / m 2 / min.

[0021] In some embodiments, the reactor system disclosed herein further comprises a three-phase separation unit fluidly connected to the reactor via a main outlet, the three-phase separation unit being configured to separate gas and solid phase materials to a gas-solid separation unit, separate the molten salt medium recirculated to the reactor via a recirculation line, and separate the carbon flow to a carbon filter vessel via a carbon flow inlet. In some embodiments, the reactor system further comprises a molten salt storage tank fluidly connected to the reactor, configured to receive the molten salt medium from the reactor via a reactor drain line. In some embodiments, the reactor system further comprises a drainage pump tank fluidly connected to the molten salt storage tank via a transfer line, the drainage pump tank being configured to pump the molten salt into the reactor via a recirculation line.

[0022] In some embodiments, a process for reacting a gaseous reactant mixture containing at least one hydrocarbon in a gas-lift reactor system to form a gaseous product containing hydrogen includes passing the gaseous reactant mixture through at least one reaction vessel containing a structured packing catalyst, contacting the gaseous reactant mixture with the packing catalyst as it rises through the at least one reaction vessel, thereby producing an output product containing at least hydrogen and carbon via thermal decomposition, and separating the output product to produce at least a concentrated carbon stream and a hydrogen / hydrocarbon stream. In some embodiments, the gaseous reactant mixture contains methane or natural gas. In some embodiments, the gaseous reactant mixture contains renewable natural gas.

[0023] In some embodiments, a process for preparing hydrogen by the reaction of hydrocarbons in the presence of a catalyst is described, which is carried out in a reactor system comprising one or more hydrocarbon supply lines supplied into one or more reactor sections containing a structured packed catalyst.

[0024] The features and advantages of the present invention will be obvious to those skilled in the art. Many modifications can be made by those skilled in the art, but such modifications will be within the spirit of the present invention. [Brief explanation of the drawing]

[0025] A more detailed description of the present invention, which has been briefly summarized above, can be obtained by referring to the embodiments of the present invention shown in the accompanying drawings and described herein. However, it should be noted that the accompanying drawings show only some embodiments of the present invention and should therefore not be considered to limit the scope of the invention, and other equally valid embodiments may be recognized. [Figure 1] This is a schematic diagram of one embodiment of a suspension catalyst molten salt reactor system. [Figure 2] This is a schematic diagram of one embodiment of a structured packed catalyst gas lift reactor system. [Modes for carrying out the invention]

[0026] Figure 1 is an exemplary schematic diagram of a molten salt pyrolysis reactor system. According to at least one embodiment, the system includes a reaction vessel 100 having at least three zones: a bottom reaction zone 103 with a catalyst, an intermediate catalyst / carbon separation zone 104, and an upper gas release zone 105. Effective conditions for the reactor temperature may be in the range of 600°C to 1000°C or 850°C to 950°C. The reactor pressure may be in the range of 1 bar (absolute pressure) to 10 bar (absolute pressure) or 5 bar (absolute pressure) to 10 bar (absolute pressure). According to some embodiments of the present invention, the catalyst is a solid catalyst. According to some embodiments, the solid catalyst is suspended in a molten salt medium.

[0027] According to at least one embodiment, the system described herein can accelerate high-temperature catalytic methane pyrolysis using a molten salt that melts below 1000°C. In some embodiments, the molten salt is stable under methane pyrolysis reaction conditions at temperatures above 700°C, preferably about 700°C to about 1050°C. In some embodiments, the molten salt is present in the reaction zone at temperatures above its melting point. For the molten salt to function as an effective support for the suspended catalyst, it is essential that it is thermally and chemically stable under pyrolysis reaction conditions. That is, the molten salt cannot be reduced by the reactant feed mixture under conditions that are dominant in the reaction zone.

[0028] According to at least one embodiment of the present invention, the system includes a conduit 101 for supplying a feed gas (natural gas or methane) to a reaction vessel 100 through a gas spurger 102. The function of the spurger is to uniformly distribute the methane or natural gas across the reactor cross-section and to facilitate the generation of small bubbles of the feed gas in the molten salt medium, which promotes effective contact between the feed gas and the catalyst. The feed gas may include a mixture of methane, hydrogen, and other light hydrocarbons. In some embodiments, methane is the component having the largest volume fraction. In some embodiments, hydrogen is the component having the largest volume fraction. According to at least one embodiment, the hydrogen fraction is present in the feed in varying amounts (but not limited to) 1 to 35% by weight. The feed gas enters the reaction vessel from either the bottom or the top of the vessel via a downward-facing conduit. The embodiment illustrated in Figure 1 shows a bottom entry configuration, but a top entry configuration is also feasible. According to one embodiment, the spurger can be any conventional spurger design capable of withstanding the reaction conditions described herein. The pyrolysis reaction primarily occurs in the bottom zone of reactor 103. Small bubbles of methane generated from the sparger rise through the molten salt medium and come into contact with suspended catalyst particles. The resulting pyrolysis reaction takes place at the contact surface between the bubbles and the catalyst sites, thereby producing at least hydrogen and elemental carbon from the conversion of methane. The elemental carbon particles resulting from the conversion of methane either move freely through the voids between the suspended catalysts or adhere to the bubbles and move upward through the carbon / catalyst separation zone 104 to the upper liquid surface of the reactor.

[0029] Unlike conventional systems that use finely divided nanoscale metal and / or metal oxide catalysts dispersed in a molten medium, some embodiments of the present invention include a suspended catalyst. According to at least one embodiment, the catalyst particles are suspended such that they have sufficient voids to allow the generated solid carbon to move out of the catalyst layer and thus prevent clogging in the catalyst layer. The flow conditions (gas flow rate and molten salt flow rate) and catalyst properties (particle size and density) are optimized to suspend the catalyst and prevent entrainment of the catalyst from the reactor. The catalyst density is approximately 1,500 kg / m³ 3 ~Approx. 3,800kg / m 3 Or approximately 2,000 kg / m 3 ~Approx. 2,500kg / m 3 The catalyst particle size may be within the range of approximately 0.6 mm to 6 mm or approximately 0.8 mm to 4 mm. Due to the size of the suspended catalyst, catalyst aggregation is reduced compared to conventional systems incorporating smaller nanoscale catalyst particles. The methane supply per unit cross-sectional area per hour is approximately 0.7 kg / m³. 2 / min ~ approx. 20kg / m 2 / min or approximately 1.4 kg / m 2 / min ~ approx. 5kg / m 2 It can be within the range of / min. The molten salt circulation flow rate is approximately 5 kg / m³. 2 / sec ~ approx. 130kg / m 2 / second or approximately 35 kg / m 2 / sec ~ approx. 75kg / m 2 It may be within the range of / second.

[0030] The bottom reaction zone 103 generates a gas stream containing solid carbon products and hydrogen. The gas stream may contain at least 50 volume percent hydrogen, preferably at least 75 volume percent hydrogen, and more preferably at least 90 volume percent hydrogen. Since no carbon dioxide is formed in this bottom reaction zone, there is no need to separate carbon dioxide from the hydrogen before it can be used in other processes. In addition to the hydrogen in the gas stream, any unreacted methane does not adversely affect most downstream processes, including ammonia synthesis. This offers advantages over other hydrogen production processes, such as steam methane reforming, which produces carbon dioxide.

[0031] The gas phase flow containing hydrogen products and unconverted methane passes through the gas release zone 105 at the top of the reactor. In some embodiments, the gas release zone at the top of the reactor is designed for initial separation of the gas phase from the encompassing molten salt droplets and carbon particles. In some embodiments, it is designed with an expansion to reduce the gas velocity within the expansion and thus improve the sedimentation of droplets and particles. In some embodiments, the gas release zone includes a demister 107 for removing molten salt droplets from the gas flow. The gas flow then exits the reactor from the top and enters the gas-solid separation unit 109 to remove encompassing carbon particles. The gas-solid separator can be any conventional design capable of handling reaction conditions, particularly high-temperature operation. Examples include cyclones, filters, and combinations of both. After exiting the separation unit, the gas, free of particles and molten salt droplets, enters the gas separation and purification unit 111 to separate the hydrogen products from the unconverted methane. The unconverted methane stream 113 is supplied back into the reactor through the feed inlet conduit 101. The hydrogen 112 produced from the reactor may be the final product or may be used in the process as a fuel gas to provide a heat source for the reactor.

[0032] In the reaction vessel 100, the secondary heat source 106 may be located either inside or outside to provide heat for the molten salt system and to regulate the reactor temperature. Figure 1 shows one possible embodiment including the external configuration of the secondary heat source 106. Those skilled in the art will understand that other configurations and locations of the secondary heat source are feasible. In some embodiments, the heater may be an electric heater made from a material capable of withstanding high temperatures. Examples include ceramic heaters or heaters made from special high-temperature alloys. In some embodiments, the heater may also be a combustion heater that uses hydrogen produced from the process as a fuel gas.

[0033] According to at least one embodiment, elemental carbon produced from the conversion of methane moves upward with the movement of bubbles and molten salt liquid and can accumulate in a carbon-rich layer 114 at the top of the reactor. Because the solid carbon product in the molten salt has lower settling properties, the solid carbon product remains in the carbon-rich layer, making separation easier. The solid carbon product can be used as a raw material for producing colored pigments, fibers, foils, cables, activated carbon, or tires. In addition, the solid carbon product can be mixed with other materials to modify the mechanical, thermal, and / or electrical properties of those materials. The final carbon form of the solid carbon product is controlled by the selection of salt, metal-containing catalyst, and reaction conditions. According to some embodiments, the carbon-rich layer includes a region near the top surface of the molten salt where carbon particles formed during the pyrolysis process accumulate due to a combination of buoyancy and lift from the gas. According to at least one embodiment, some of the carbon contained in the carbon-rich layer 114 at the top of the reaction vessel can be recovered from the reactor through a circulating flow of molten salt liquid, which flows 115 into a gas-liquid-solid three-phase separation vessel 116. Those skilled in the art will understand that other methods for recovering the carbon contained in the carbon-rich layer are feasible, including, for example, the use of a skimmer pump or conveyor mechanism. In the gas-liquid-solid three-phase separator, the separated gas 120 is fed into a gas-solid separation unit 109, while the molten salt liquid remains on one side 117 of the separation unit. The solid carbon flows over the overflow weir 119 of the separator and accumulates on the opposite side 118 of the separator. The carbon-rich zone 118 within the separator still contains a small amount of molten salt liquid and can be drawn into a high-temperature filtration vessel 122 to recover the carbon product 123. According to at least one embodiment, the filtration vessel facilitates a physical process of separating carbon particles from the molten salt by passing the carbon molten salt slurry through a filter medium that does not allow carbon particles to pass through. The molten salt liquid, entrained with carbon particles, is returned to the molten salt storage tank 127. The molten salt-rich zone 117 in the separator may still contain some fine carbon particles, which can be discharged into the molten salt storage tank 127 after passing through the heat exchanger 126 and cooled to the operating temperature of the storage tank.According to some embodiments, a heat exchanger 126 is optionally included depending on the operating temperature of the molten salt storage tank 127 and the pump 130. According to some embodiments, the heat exchanger is a specific form of cooling device that lowers the temperature of the molten salt medium. The molten salt storage tank may be any container that can contain molten salt. According to some embodiments, the inner wall of the container is lined with a refractory material that is resistant to salt corrosion. The molten salt liquid in the storage tank 127 can be transferred to the pump drain tank 129 through a conduit 128 based on the pressure difference between the two tanks. Both tanks may be designed to have self-draining capabilities, such as a non-uniform bottom design. A high-temperature molten salt pump 130 submerged in the pump drain tank 129 is used to circulate the molten salt back to the bottom of the reactor. Self-draining capabilities may be useful when performing maintenance on the tanks and the pumps contained therein. A primary heating device 131 is used to heat the circulating molten salt flow to reach a target reactor temperature. According to some embodiments, the heating device is a heat exchanger. In an alternative configuration, the pump 130 can be submerged in the storage tank 127, thereby eliminating the need for a second tank.

[0034] Figure 2 is an illustrative schematic diagram of a structured packed catalyst gas lift reactor system. According to at least one embodiment of the present invention, the system comprises a reaction vessel 200 containing a structured packed catalyst 203 for the conversion of methane. Those skilled in the art will understand that the term structured packed catalyst may refer to a structured packing comprising a catalytic material, configured to allow reactants to flow through the packing, and thus allowing such reactants to come into contact with the catalytic material, thereby causing a reaction to occur and produce a specific product material.

[0035] According to at least one embodiment of the present invention, the structured packed catalyst is made from a metal element having catalytic activity for the conversion of methane. According to some embodiments, the structured packed catalyst has a high void capacity to help reduce flow resistance in the reactor and improve the molten salt circulation rate. The void capacity of the packed catalyst can vary in the range of about 90% to 99% or about 97% to 99%. The natural gas or methane feed 201, along with the recirculated methane 211, enters the reaction vessel from either the bottom or the top of the vessel via a downward-facing conduit. A gas sparger 202 is used to generate small bubbles and distribute the gas uniformly across the cross-section of the reaction vessel. According to one embodiment, the sparger can be any conventional sparger design capable of withstanding the reaction conditions described herein. The methane gas flows through the structured packed catalyst in the form of bubbles in the molten salt. The presence of bubbles in the reactor creates a hydrostatic pressure difference between reactor 200 and the recirculation loop, which includes the three-phase separator 206, recirculation conduit 217, and primary heat exchanger 219. This hydrostatic pressure difference generates the circulation of the molten salt liquid through the reactor and recirculation loop, which is referred to herein as gas lift. The high void capacity of the structured packed catalyst provides improved contact between methane and the catalyst material and further promotes the movement of carbon from the reaction zone so that carbon fouling, a problem encountered in conventional reactor designs, is significantly minimized. The structured packed catalyst provides a low pressure drop within the reactor, which helps maintain the circulation of the molten salt within the reactor. According to some embodiments, the circulation of the molten salt arises from foaming and gas lift within the reactor. The actual circulation flow rate that can be achieved depends on the reactor and recirculation loop configuration, the methane supply rate, the flow resistance from the structured packed catalyst, and the reactor operating conditions. According to some embodiments, the reactor system may optionally include a pump to facilitate circulation within the reactor, either in combination with the reactor bubble lift disclosed herein or as an independent circulation mechanism. According to some embodiments, the methane supply per unit cross-sectional area per hour is approximately 1 kg / m³ 2 / min ~ approx. 25kg / m 2 / min or approximately 5kg / m 2 / min ~ approx. 15kg / m2 It could be within the range of / minutes.

[0036] According to at least one embodiment, other components described herein may be used in combination with a reactor, including a structured packed catalyst design comprising a three-phase separation unit 206, a gas-solid separation unit 208, a gas separation and purification unit 209, a high-temperature carbon filtration unit 215, a primary heat exchanger 219, and a secondary heat source 204 for the reactor. According to some embodiments, a molten salt storage tank 220 and a pump drain tank 221 are also used in this concept, together with a molten salt pump 222, for filling or discharging molten salt, reactor maintenance, storage and melting molten salt, and optionally for improving the circulation of molten salt within the reactor loop. In some embodiments, the molten salt pump 222 may operate at a relatively low temperature, at least above the melting temperature of the molten salt blend. For example, for a system operating with a molten salt blend having a melting temperature of 660°C, the molten salt pump may operate at a temperature above about 700°C to minimize the risk of molten salt solidification. Preferably, the molten salt pump may operate at a temperature about 50–100°C above the melting temperature of the molten salt blend. In some embodiments, the gas lift reactor may be equipped with a gas release section at the top of the reactor, allowing a portion of the gas flow to exit the reactor from the top and enter the gas-solid separation unit 208. The other portion of the gas flow, along with the carbon and molten salt liquid, may exit the reactor from the side and enter the three-phase separation unit 206. The embodiments are described below. 1 A process for the thermal decomposition of methane in a molten salt medium, Exposing methane gas to a molten salt medium and a solid catalyst within the volume of a reaction vessel under conditions effective for converting at least a portion of methane to hydrogen and solid carbon, This includes removing at least a portion of the solid carbon, The molten salt medium comprises a halide salt and a chloride salt. A process in which the solid catalyst is placed in the reaction vessel either as suspended particles in the molten salt medium or in a structured packing form. Appearance 2 A reactor system for carrying out a chemical reaction, comprising one or more hydrocarbon supply lines supplied to one or more reactor sections containing a molten salt and a solid catalyst, wherein the solid catalyst is disposed in the reactor either as suspended particles in the molten salt or in a structured packing form, and the one or more reactor sections comprises a lower part of the reaction vessel and an upper part of the reaction vessel. Appearance 3 The reactor system according to embodiment 2, wherein the solid catalyst is disposed in the reactor as suspended particles in the molten salt. Pattern 4 The suspended catalyst particles are confined to the lower part of the reaction vessel so that the catalyst particles can move freely within the lower part of the reaction vessel. The reactor is configured to perform a thermal decomposition reaction that results in the generation of solid carbon particles by causing methane gas to foam through the molten salt so that methane bubbles come into contact with the suspended catalyst particles. The reactor system according to embodiment 3, wherein the reactor is further configured to allow the solid carbon particles produced by the thermal decomposition reaction to move upward with the movement of the bubbles and the flow of the molten salt to accumulate in the carbon-rich layer located at the top of the reaction vessel. Appearance 5 The methane supply flow rate is approximately 0.7 kg / m³. 2 / min ~ approx. 20kg / m 2 The reactor system according to embodiment 4, wherein the rate is / min. Appearance 6 The reaction vessel further comprises a pump located outside the reaction vessel, The molten salt is circulated to and from the storage tank, which is fluidly connected to the reaction vessel. The reactor system according to embodiment 3, wherein the pump drives the circulation of the molten salt and controls the flow rate of the molten salt circulation. Appearance 7 The flow rate of the molten salt circulation is approximately 5 kg / m³. 2 / sec ~ approx. 130kg / m 2 The reactor system according to embodiment 6, wherein the rate is / second. Appearance 8 The methane supply flow rate and molten salt flow rate, in combination, promote the thermal decomposition reaction, thereby generating solid carbon particles, and further, The reactor system according to embodiment 3, wherein bubbles are introduced when bubbles move from the lower part of the reaction vessel to the upper part of the reactor, thereby promoting the separation of the carbon particles generated from the suspension catalyst. Appearance 9 The reactor system according to embodiment 2, wherein the solid catalyst is arranged in the reaction vessel in a structured packed form. Appearance 10 The reactor system according to embodiment 9, wherein the solid catalyst, arranged in a structured packed form within the reaction vessel, has a void volume of approximately 90% to approximately 99%.

Claims

1. A process for the thermal decomposition of methane in a molten salt medium, Exposing methane gas to a molten salt medium and a solid catalyst within the volume of a reaction vessel under conditions effective for converting at least a portion of methane to hydrogen and solid carbon, This includes removing at least a portion of the solid carbon, The molten salt medium comprises a halide salt and a chloride salt. The solid catalyst is disposed in the reaction vessel either as suspended particles in the molten salt medium or in a structured packed form, and the catalyst particles are distributed at a density of 1,500 kg / m³. ３ ~3,800kg / m ３ A process having a density and an average size of 0.6 mm to 6 mm in diameter.

2. A reactor system for carrying out a chemical reaction, comprising one or more hydrocarbon supply lines supplied to one or more reactor sections within a reaction vessel, wherein the reactor section comprises a molten salt and a solid catalyst, the solid catalyst being disposed in the reactor either as suspended particles in the molten salt or in a structured packed form, and the one or more reactor sections comprising a lower part of the reaction vessel and an upper part of the reaction vessel, the catalyst particles being 1,500 kg / m³ ３ ~3,800kg / m ３ A reactor system having a density and an average size of 0.6 mm to 6 mm in diameter.

3. The reactor system according to claim 2, wherein the solid catalyst is disposed in the reactor as suspended catalyst particles in the molten salt.

4. The suspended catalyst particles are confined to the lower part of the reaction vessel so that the catalyst particles can move freely within the lower part of the reaction vessel. The reactor is configured to perform a thermal decomposition reaction that results in the generation of solid carbon particles by causing methane gas to foam through the molten salt so that methane bubbles come into contact with the suspended catalyst particles. The reactor system according to claim 3, wherein the reactor is further configured to allow the solid carbon particles produced by the thermal decomposition reaction to move upward with the movement of the bubbles and the flow of the molten salt to accumulate in the carbon-rich layer located at the top of the reaction vessel.

5. The reactor sets the methane supply flow rate to 0.7 kg / m³. ２ / min~20kg / m ２ The reactor system according to claim 4, configured to enable a rate of 1 / minute.

6. The reaction vessel further comprises a pump located outside the reaction vessel, The molten salt is circulated to and from the storage tank, which is fluidly connected to the reaction vessel. The reactor system according to claim 4, wherein the pump drives the circulation of the molten salt and controls the flow rate of the molten salt circulation.

7. The reactor controls the flow rate of the molten salt circulation to 5 kg / m³. ２ / sec ~ 130kg / m ２ The reactor system according to claim 6, configured to enable a rate of / second.

8. The reactor combines the methane supply stream and the molten salt stream to produce bubbles that promote the thermal decomposition reaction, thereby generating solid carbon particles, and further, The reactor system according to claim 6, configured to facilitate the separation of the solid carbon particles generated from the suspended catalyst particles when bubbles move from the lower part of the reaction vessel to the upper part of the reactor.

9. The reactor system according to claim 2, wherein the solid catalyst is arranged in the reaction vessel in a structured packed form.

10. The reactor system according to claim 9, wherein the solid catalyst, arranged in a structured packed form within the reaction vessel, has a void volume of 90% to 99%.

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