Method and device for continuous hydrogen production by catalytic cracking of methane based on carbon-based circulating supports

Abstract

This invention provides a method and apparatus for continuous hydrogen production via methane catalytic cracking based on a carbon-based circulating carrier, comprising the following steps: selecting a carbon-based material as a circulating carrier and feeding it into a cracking reactor; introducing methane into the cracking reactor, where it undergoes a cracking reaction with the circulating carrier under anaerobic conditions, generating deposited carbon that is at least partially deposited on the surface and within the pores of the circulating carrier, forming a carbon-carrying carrier; drawing the gas generated from the cracking reactor outlet, removing the carbon-carrying carrier after gas-solid separation; introducing the carbon-carrying carrier into a regeneration reactor; introducing a regeneration medium into the regeneration reactor to cause the deposited carbon on the carbon-carrying carrier to undergo a gasification reaction to obtain a regenerated carrier, adjusting the deposited carbon removal ratio and solids removal ratio, and then returning the regenerated carrier to the cracking reactor to participate in the cracking reaction. This invention has a reasonable structure, ensuring the circulating flow of the carrier to participate in the cracking reaction, and can meet the requirements for long-term stable industrial operation.

Description

Technical Field

[0001] This invention relates to the field of hydrogen production technology, and more specifically, to a method and apparatus for continuous hydrogen production by catalytic cracking of methane based on a carbon-based circulating carrier. Background Technology

[0002] Methane (CH4) is not only an important primary energy source and chemical feedstock, but also a gas with a significant greenhouse effect. Depending on the accounting methods and feedback effect settings used, the global warming potential (GWP100) of methane on a 100-year timescale is typically in the range of approximately 27-30. With the increasing demand for emission control from natural gas development and utilization, coal mine gas, and related industrial processes, how to achieve high-value resource utilization while reducing emissions has become a core focus of current engineering and industrial attention.

[0003] In current technologies, hydrogen energy is considered an important low-carbon energy carrier, but industrial hydrogen production still relies primarily on fossil fuel routes. Steam methane reforming (SMR) has advantages in terms of maturity and relatively low cost, but it also comes with high CO2 emission intensity. According to literature, its typical emission intensity ranges from approximately 7.5 to 12 tCO2 / tH2, requiring carbon capture and storage / utilization technologies to significantly reduce its carbon footprint. Unlike steam methane reforming (SMR), catalytic cracking / thermal catalytic decomposition of methane (CDM / TCD) follows the reaction CH4 → C(s) + 2H2(g), theoretically enabling a "COx-free direct generation" route on the hydrogen production side, and can co-produce carbon-fixing materials. Therefore, it has potential advantages in the synergistic direction of "low-carbon hydrogen production + solid carbon products." However, related studies have pointed out that this technology has many drawbacks, including: high demand for high-temperature drive, activity decay caused by carbon buildup, increased bed pressure drop and blockage, as well as difficulties in gas-solid separation and insufficient stability of solid circulation during continuous scale-up. These drawbacks are the main problems limiting its application in industry.

[0004] In terms of catalyst systems, metal-based catalysts (such as Ni / Fe / Co) can reduce the onset temperature of methane catalytic cracking / thermal catalytic decomposition reactions and increase the rate to a certain extent. However, these catalysts are prone to sintering, phase transformation and deactivation under high-temperature carbon deposition environment. Their regeneration process usually requires the introduction of oxidizing gas to remove carbon deposits. During this process, the catalyst suffers irreversible structural damage and may bring the risk of impurity contamination to the hydrogen production side.

[0005] In contrast, carbon-based materials offer advantages such as readily available raw materials, resistance to impurities, and certain autocatalytic characteristics, and have been widely studied for the thermal catalytic decomposition of methane. However, they also face common problems such as deposited carbon covering active sites and clogging catalyst pores, leading to reaction instability. Furthermore, improper control of regeneration conditions and regeneration depth (i.e., the proportion of deposited carbon removal) can result in excessive gasification or ablation of the carbon framework structure, leading to unsustainable performance and failing to meet the requirements for long-term stable industrial operation. Therefore, a continuous hydrogen production method for methane catalytic cracking based on carbon-based circulating supports is urgently needed to address these issues. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method and apparatus for continuous hydrogen production by catalytic cracking of methane based on a carbon-based circulating support, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides a continuous hydrogen production method for methane catalytic cracking based on a carbon-based circulating support, comprising the following steps: Carbon-based materials were selected as the circulating carriers and sent to the pyrolysis reactor. Methane is fed into a cracking reactor and undergoes a cracking reaction with a circulating carrier under anaerobic conditions. The generated deposited carbon is at least partially deposited on the surface and in the pores of the circulating carrier, forming a carbon-carrying carrier. The gas produced by pyrolysis is drawn out from the outlet of the pyrolysis reactor, and after gas-solid separation, the carbon-carrying carrier is removed, and then fine dust removal is performed to obtain low-dust gas. The carbon-carrying carrier enters the regeneration reactor; In the regeneration reactor, a regeneration medium is introduced to cause the deposited carbon on the carbon-carrying carrier to undergo a gasification reaction to obtain a regenerated carrier. The ratio of deposited carbon removal and solids removal is adjusted, and the regeneration tail gas is discharged. The regenerated carrier is then returned to the pyrolysis reactor to continue participating in the pyrolysis reaction.

[0008] Furthermore, the discharge section of the regeneration reactor is equipped with a carbon discharge port for continuously or intermittently discharging a portion of the carbon products.

[0009] Furthermore, the circulating carrier includes one or more of activated carbon, carbon black, porous carbon, mesoporous carbon, carbon fiber, carbon felt, graphitized carbon, hard carbon-soft carbon composite material, and composite particles formed by coating carbon material onto an inert framework. The circulating carrier is in the form of powder, granules, spherical particles, honeycomb, or carrier coating. The particle size of the circulating carrier is 75-150 μm.

[0010] Furthermore, the temperature of the pyrolysis reactor is 850-1050℃, and the pressure is 0.1-0.4MPa; The temperature of the regeneration reactor is 650-950℃.

[0011] Furthermore, the regeneration medium includes one or both of CO2 and water vapor; When both coexist, the volume ratio of CO2 to water vapor is 0-10, where 0 indicates that the regeneration medium is only water vapor.

[0012] Furthermore, the carbon removal rate is 20%-70%; Once the baseline bed pressure drop ΔP0 is established in the initial stage of stable operation of the pyrolysis reactor, if the measured bed pressure drop ΔP of the pyrolysis reactor during operation satisfies ΔP / ΔP0 = 1.05-1.50, it is determined that a carbon deposition accumulation trend has occurred, and the carbon deposition removal ratio and solids removal ratio are adjusted accordingly. The adjustment of the deposited carbon removal ratio and solids removal ratio includes the following steps: When the bed pressure drop ΔP / ΔP0 of the pyrolysis reactor increases to a preset threshold and the methane conversion rate in the pyrolysis reactor decreases, the proportion of deposited carbon removal is increased. When the bed pressure drop ΔP / ΔP0 of the pyrolysis reactor increases to a preset threshold and the methane conversion rate remains within a preset stable range, the solids removal ratio is increased, and the proportion of deposited carbon removal is increased accordingly. When the CO to CO2 volume ratio at the regeneration tail gas outlet of the regeneration reactor is lower than the set value and the methane conversion rate decreases, the proportion of deposited carbon removal can be increased by one or more of the following methods: increasing the regeneration medium flow rate, increasing the regeneration steam ratio, increasing the regeneration temperature, and extending the regeneration residence time. When the volume ratio of CO to CO2 at the outlet of the regeneration reactor is higher than the set value and the activity of the circulating carrier gradually decreases, the proportion of deposited carbon removal and the solids discharge ratio should be reduced accordingly. The solids removal ratio is defined as the proportion of the mass of solid carbon separated and recovered as a product to the total mass of solid carbon generated from methane cracking within the same statistical period, with a solids removal ratio of 0.1%–15%.

[0013] An apparatus for realizing a continuous hydrogen production method by catalytic cracking of methane based on a carbon-based circulating carrier, characterized in that it includes a cracking reactor, a regeneration reactor, a cracking-side gas-solid separation unit, and a regeneration-side gas-solid separation unit. The top of the pyrolysis reactor is provided with a pyrolysis gas outlet, which is connected to the pyrolysis-side gas-solid separation unit. The bottom of the pyrolysis reactor is provided with a pyrolysis-side carrier discharge outlet, the top of the regeneration reactor is provided with a regeneration-side carrier inlet and a regeneration tail gas outlet, and the bottom of the regeneration reactor is provided with a regeneration medium inlet and a solid discharge outlet. A sealed return and carrier circulation unit is provided between the pyrolysis-side waiting carrier discharge port and the regeneration-side waiting carrier inlet at the top of the regeneration reactor, and between the regenerated carrier discharge port at the bottom of the regeneration reactor and the carrier return port on the pyrolysis reactor. The regenerated exhaust gas outlet is connected to the regenerated side gas-solid separation unit.

[0014] Furthermore, the sealed return and carrier circulation unit includes a first flow sealing valve, a purge desorption assembly, a second flow sealing valve, a riser pipe, and a return inclined pipe. The pyrolysis-side prepared carrier discharge port is connected to the regeneration-side prepared carrier inlet at the top of the regeneration reactor via the first flow sealing valve. The regenerated carrier outlet at the bottom of the regeneration reactor is connected to the carrier return port of the pyrolysis reactor via a purge and desorption assembly, a second flow sealing valve, a riser, and a return inclined pipe.

[0015] Furthermore, a gas distribution plate is provided at the bottom of the pyrolysis reactor, the gas distribution plate is connected to the inner wall of the pyrolysis reactor, the bottom of the gas distribution plate is connected to the methane inlet pipe, and a carrier replenishment port is provided at the bottom of the pyrolysis reactor; The regeneration reactor is equipped with a carbon discharge port on the discharge section, and the carbon discharge port is connected to the grading and screening end. The purging and desorption assembly includes an inert purging chamber disposed on a transition cavity between the regenerated carrier outlet and the second flow sealing valve in the regeneration reactor, the inert purging chamber being connected to a pipeline of inert gas.

[0016] Furthermore, both the pyrolysis-side gas-solid separation unit and the regeneration-side gas-solid separation unit include a cyclone separator and a settling device; The settling device is connected in series with the cyclone separator. The input end of the settling device is connected to the pyrolysis gas outlet or the regeneration tail gas outlet, and the output end of the settling device is connected to the input end of the cyclone separator. The cyclone separator of the pyrolysis-side gas-solid separation unit is connected to a high-temperature filter, and the output end of the high-temperature filter is connected to a hydrogen purification end. The output end of the cyclone separator of the regeneration side gas-solid separation unit is connected to the exhaust gas utilization and treatment end.

[0017] Furthermore, the pyrolysis reactor is a bubble bed pyrolysis reactor, a circulating fluidized bed reactor, or a riser reactor; The regeneration reactor is a bubbling fluidized bed, a circulating fluidized bed, or a moving bed regenerator.

[0018] Furthermore, the regeneration reactor is a moving bed regenerator with axial functional partitions. The moving bed regenerator includes a first regeneration zone and a second regeneration zone that are interconnected. The first regeneration zone is located at the upper part of the regeneration reactor, and the second regeneration zone is located at the lower part of the regeneration reactor.

[0019] Furthermore, the regeneration medium inlet is divided into at least two gas distribution branches via an internal or external manifold of the moving bed regenerator. One gas distribution branch is connected to the first gas distributor at its bottom, and the other gas distribution branch is connected to the second gas distributor at its lower part. Each of the two gas distribution branches is equipped with a flow regulating component.

[0020] Furthermore, there are two regeneration medium inlets, one of which is located at the bottom of the moving bed regenerator and connected to the first gas distributor at its bottom; Another regeneration medium inlet is located on the lower side wall of the moving bed regenerator and connected to the second gas distributor at its bottom.

[0021] Furthermore, the inert purge chamber includes a first purge-desorption chamber and a second purge-desorption chamber, which are arranged in series along the flow direction of the regenerated carrier. The first purge desorption chamber and the second purge desorption chamber are connected in series vertically by gravity. The regenerated carrier outlet at the bottom of the regeneration reactor is connected to the solid inlet at the top of the first purge desorption chamber. The solid outlet at the bottom of the first purge desorption chamber is connected to the solid inlet at the top of the second purge desorption chamber. The solid outlet at the bottom of the second purge desorption chamber is connected to the input end of the second flow sealing valve. The output end of the second flow sealing valve is then connected to the lower end of the riser pipe, and the upper end of the riser pipe is connected to the carrier return port on the pyrolysis reactor through the return inclined pipe. Beneficial effects

[0022] By participating in the pyrolysis reaction through a circulating carrier, some of the generated carbon deposits on the surface and within the pores of the circulating carrier, forming a carbon-carrying carrier. Another portion of the deposited carbon will detach from the carrier surface under gas-solid disturbance or friction, forming free carbon particles. The carbon-carrying carrier and the deposited carbon will enter the regeneration reactor for gasification along with the bed solids. By adjusting the carbon removal ratio, the regeneration tail gas is discharged. After gasification and regeneration, the carbon-carrying carrier becomes a regenerated carrier and flows back to the pyrolysis reactor. This avoids the deposited carbon covering the active sites of the carrier and clogging the pores, allowing it to continue participating in the pyrolysis reaction. By adjusting the carbon removal ratio and the solids discharge ratio, the carbon skeleton structure is prevented from being over-gasified or ablated, thus avoiding unsustainable performance and meeting the requirements for long-term stable operation in industrial applications. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a flowchart of a continuous hydrogen production method for methane catalytic cracking based on a carbon-based circulating support according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an apparatus for a continuous hydrogen production method based on a carbon-based circulating carrier using methane catalytic cracking according to an embodiment of the present invention. Figure 3 This is a schematic diagram of an apparatus for a continuous hydrogen production method based on a carbon-based circulating carrier using methane catalytic cracking, according to an embodiment of the present invention. In the diagram: 1. Cracking reactor; 2. First flow sealing valve; 3. Regeneration reactor; 4. Purge and desorption assembly; 5. Second flow sealing valve; 6. Riser; 7. Return inclined pipe; 8. Cracking-side gas-solid separation unit; 9. High-temperature filter; 10. Hydrogen purification end; 11. Regeneration-side gas-solid separation unit; 12. Tail gas utilization and treatment end; 13. Carbon discharge port; 14. Grading and screening end; 15. Cracking-side pre-regenerated carrier discharge port; 16. Regeneration-side pre-regenerated carrier inlet; 17. Regenerated carrier outlet; 18. Carrier return port. Detailed Implementation

[0024] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0025] like Figure 1 As shown, the present invention provides a technical solution: a continuous hydrogen production method for methane catalytic cracking based on a carbon-based circulating support, comprising the following steps: Carbon-based materials were selected as the circulating carriers and sent to pyrolysis reactor 1; Methane is fed into cracking reactor 1 and undergoes a cracking reaction with the circulating carrier under anaerobic conditions. The generated deposited carbon is at least partially deposited on the surface and in the pores of the circulating carrier, forming a carbon-carrying carrier. The gas produced by pyrolysis is drawn out from the outlet of pyrolysis reactor 1, and after gas-solid separation, the carbon-carrying carrier is removed, and then fine dust removal is performed to obtain low-dust gas. The carbon-carrying carrier enters the regeneration reactor 3; In regeneration reactor 3, a regeneration medium is introduced to cause the deposited carbon on the carbon-carrying carrier to undergo a gasification reaction, resulting in a regenerated carrier. The carbon removal ratio and solids discharge ratio are adjusted, and the regeneration tail gas is discharged. The regenerated carrier is then returned to pyrolysis reactor 1 to continue participating in the pyrolysis reaction. This design utilizes a circulating carrier in the pyrolysis reaction. Part of the generated deposited carbon is deposited on the surface and within the pores of the circulating carrier, forming a carbon-carrying carrier. Another part of the deposited carbon will detach from the carrier surface under gas-solid disturbance or friction, forming free carbon particles. The carbon-carrying carrier and the deposited carbon will enter the regeneration reactor 3 along with the bed solids for gasification. The regeneration tail gas is discharged by adjusting the carbon removal ratio. After gasification and regeneration, the carbon-carrying carrier becomes a regenerated carrier and is returned to pyrolysis reactor 1. This avoids the deposited carbon covering the active sites of the carrier and clogging the pores, allowing it to continue participating in the pyrolysis reaction. By adjusting the carbon removal ratio, excessive gasification or ablation of the carbon skeleton structure is avoided, which could lead to unsustainable performance. This design meets the requirements for long-term stable operation in industrial applications.

[0026] The discharge section of the regeneration reactor 3 is equipped with a carbon discharge port 13 for continuous or intermittent discharge of a portion of the carbon product. This design, through the continuous or intermittent discharge of a portion of the carbon product via the carbon discharge port 13, coordinates with the replenishment of the circulating carrier. The carbon discharge product and the replenishment strategy of the circulating carrier are linked to the deposition carbon removal ratio / carrier circulation volume to stabilize the system carbon inventory and avoid agglomeration and blockage.

[0027] The recycling carrier includes one or more of the following: activated carbon, carbon black, porous carbon, mesoporous carbon, carbon fiber, carbon felt, graphitized carbon, hard carbon-soft carbon composite material, and composite particles formed by coating carbon material onto an inert framework. The circulating carrier can be in the form of powder, granules, spherical particles, honeycomb, or carrier coating. The particle size of the circulating carrier is 75-150 μm; Recycling supports also include one or more of the following: native carbon materials, carbon materials modified by surface functional group regulation, defect regulation, pore structure regulation, and a small amount of co-catalytic components; The small amount of co-catalytic components includes one or more of transition metals, alkali metals, alkaline earth metals, and oxides, carbonates and salts of the above metals, wherein the transition metals include Ni, Fe, Co, Cu or Mo; and the alkali metals and alkaline earth metals include K, Na, Ca or Mg. The modification can be achieved by one or more of the following methods: impregnation, ion exchange, deposition-precipitation, sol-gel, in-situ growth, and plasma thermal treatment.

[0028] The temperature of pyrolysis reactor 1 is 850-1050℃, and the pressure is 0.1-0.4MPa; The temperature of regeneration reactor 3 is 650-950℃.

[0029] The regeneration medium includes one or both of CO2 and water vapor; When both coexist, the volume ratio of CO2 to water vapor is 0-10, where 0 indicates that the regeneration medium is only water vapor.

[0030] The carbon removal rate is 20%-70%; Once the baseline bed pressure drop ΔP0 is established in the initial stage of stable operation of the pyrolysis reactor 1, if the measured bed pressure drop ΔP of the pyrolysis reactor 1 during operation satisfies ΔP / ΔP0 of 1.05-1.50, preferably 1.10-1.30, then it is determined that a carbon deposition accumulation trend has occurred, and the carbon deposition removal ratio and solids removal ratio are adjusted accordingly. Adjusting the deposition carbon removal ratio and solids removal ratio includes the following steps: When the bed pressure drop ΔP / ΔP0 of the cracking reactor 1 increases to a preset threshold and the methane conversion rate in the cracking reactor 1 decreases, the proportion of deposited carbon removal is increased. When the bed pressure drop ΔP / ΔP0 of the cracking reactor 1 increases to the preset threshold and the methane conversion rate remains within the preset stable range, the solids discharge ratio is increased and the proportion of deposited carbon removal is increased accordingly. When the CO / CO2 volume ratio at the regeneration tail gas outlet of regeneration reactor 3 is lower than the set value and the methane conversion rate decreases, the carbon removal ratio is increased by one or more of the following methods: increasing the regeneration medium flow rate, increasing the regeneration steam ratio, increasing the regeneration temperature, and extending the regeneration residence time. The CO / CO2 volume ratio is controlled between 0.50 and 1.20. When the volume ratio of CO to CO2 at the outlet of the regeneration tail gas of the regeneration reactor 3 is higher than the set value and the activity of the circulating carrier gradually decreases, the proportion of deposited carbon removal and the solids discharge ratio are reduced accordingly. The solids discharge ratio is defined as the proportion of the mass of solid carbon separated and recovered as product within the same statistical period to the total mass of solid carbon generated from methane cracking. This ratio ranges from 0.1% to 15%. Solid carbon refers to the mass of solid carbon discharged through carbon discharge port 13 and graded and screened at the grading and screening end 14, after which it is recovered as product. The total carbon generated refers to the total amount of solid carbon generated from the cracking of methane in cracking reactor 1 within the statistical period. This design employs a hierarchical control logic—"cracking-side state criterion - regeneration-side intensity criterion - system-level carbon inventory adjustment"—through closed-loop control. In this study, the bed pressure drop ΔP / ΔP0 and methane conversion rate of pyrolysis reactor 1 are used to characterize the operating status of the pyrolysis side: ΔP / ΔP0 reflects the change in flow resistance caused by the accumulation of deposited carbon and free carbon in the bed, and the methane conversion rate reflects whether the activity window of the circulating carrier structure is sufficiently maintained; the CO / CO2 ratio and H2 generation in the discharged regeneration tail gas are used to characterize the gasification intensity and deposited carbon removal rate on the regeneration side, and serve as indicators for inferring the deposited carbon removal ratio; the solids discharge ratio, the feed amount of the circulating carrier, and the deposited carbon removal ratio together constitute system-level carbon inventory adjustment variables, used to control the total carbon inventory in the system to be within a safe window, avoiding agglomeration, blockage, and activity decay; when ΔP / ΔP0 increases and the methane conversion rate decreases, it indicates that carbon accumulation and activity decay coexist on the pyrolysis side, and the deposited carbon removal ratio should be increased first; when ΔP / ΔP0 increases but the methane conversion rate remains stable, it indicates that free carbon or deposited carbon on the outer surface of the system is the main accumulation, and the solids discharge ratio should be increased first, supplemented by a moderate increase. The carbon removal ratio is as follows: When the CO to CO2 volume ratio at the regeneration outlet is lower than the set value and the methane conversion rate decreases, it indicates insufficient regeneration. One or more methods should be used to increase the carbon removal ratio, such as increasing the regeneration medium flow rate, steam ratio, regeneration temperature, or extending the regeneration residence time. When the CO to CO2 volume ratio at the regeneration outlet remains consistently high while the activity of the circulating carrier gradually decreases, it indicates that the regeneration may be too strong. The carbon removal ratio should be appropriately reduced, and the amount of solids discharged from the carbon outlet should be decreased to avoid excessive gasification of the carbon skeleton. The carbon removal ratio is equivalent to the regeneration depth. The total apparent gas velocity of the regeneration medium is 0.005-0.10 m / s, preferably 0.01-0.06 m / s. When only CO2 regeneration is used, the apparent CO2 gas velocity is 0.005-0.08 m / s, preferably 0.01-0.05 m / s. When CO2 and steam are used for co-regeneration, the apparent steam gas velocity is 0.003-0.06 m / s, preferably 0.005-0.03 m / s.

[0031] In continuous hydrogen production, the solids-to-gas ratio is preferably achieved through a combination of low-proportion continuous emissions and condition-triggered enhanced emissions. During normal operation, a low solids-to-gas ratio is maintained to stabilize the system's carbon inventory. When pressure drop increases, free carbon accumulation intensifies, or conversion rate decreases, the solids-to-gas ratio can be temporarily increased in conjunction with enhanced deposited carbon removal to quickly restore stable system operation. Preferably, this ratio is controlled within the range of 0.1%–15%. During normal operation, the solids-to-gas ratio is preferably 0.1%–3%, more preferably 0.5%–2%, to maintain stable system carbon inventory. When pressure drop in the cracking reactor bed increases, free carbon accumulation intensifies, or methane conversion rate decreases, the solids-to-gas ratio can be temporarily increased to 3%–15%, more preferably 5%–10%, in conjunction with enhanced deposited carbon removal to quickly restore stable system operation.

[0032] An apparatus for realizing a continuous hydrogen production method based on carbon-based circulating carrier for catalytic cracking of methane includes a cracking reactor 1, a regeneration reactor 3, a cracking-side gas-solid separation unit 8, and a regeneration-side gas-solid separation unit 11. The top of the pyrolysis reactor 1 is provided with a pyrolysis gas outlet, which is connected to the pyrolysis-side gas-solid separation unit 8. The bottom of the pyrolysis reactor 1 is provided with a pyrolysis-side carrier discharge port 15, the top of the regeneration reactor 3 is provided with a regeneration-side carrier inlet 16 and a regeneration tail gas outlet, and the bottom of the regeneration reactor 3 is provided with a regeneration medium inlet and a solid discharge port. A sealed material return and carrier circulation unit is provided between the pyrolysis-side waiting carrier discharge port 15 and the regeneration-side waiting carrier inlet 16 at the top of the regeneration reactor 3, and between the regenerated carrier discharge port 17 at the bottom of the regeneration reactor 3 and the carrier return port 18 on the pyrolysis reactor 1. The regeneration tail gas outlet is connected to the regeneration-side gas-solid separation unit 11. This design involves sending a circulating carrier into the cracking reactor 1 to undergo a cracking reaction with methane. Part of the generated deposited carbon is deposited on the surface and within the pores of the circulating carrier, forming a carbon-carrying carrier. Another part of the deposited carbon will detach from the carrier surface under gas-solid disturbance or friction, forming free carbon particles. The carbon-carrying carrier and the deposited carbon will flow with the bed solids through the sealed return material and enter the regeneration reactor 3 for gasification together with the carrier circulation unit. By adjusting the deposited carbon removal ratio, the regeneration tail gas is discharged. After gasification and regeneration, the carbon-carrying carrier becomes a regenerated carrier and flows back to the cracking reactor 1. This avoids the deposited carbon covering the active sites of the carrier and clogging the pores, allowing it to continue participating in the cracking reaction. By adjusting the deposited carbon removal ratio, the circulating carrier can be recycled, avoiding excessive gasification or ablation of the carbon skeleton structure, which would lead to unsustainable performance. This design can meet the requirements of long-term stable operation in industrial applications.

[0033] The sealed return and carrier circulation unit includes a first flow sealing valve 2, a purge desorption assembly 4, a second flow sealing valve 5, a riser 6, and a return inclined pipe 7. The pyrolysis-side carrier discharge outlet 15 is connected to the regeneration-side carrier inlet 16 at the top of the regeneration reactor 3 via the first flow sealing valve 2. The regenerated carrier outlet 17 at the bottom of the regeneration reactor 3 is connected to the carrier return inlet 18 of the pyrolysis reactor 1 via the purge-desorption assembly 4, the second flow sealing valve 5, the riser 6, and the return inclined pipe 7. This design achieves a closed-loop carrier circulation between the pyrolysis reactor 1 and the regeneration reactor 3 through a "carrier to be generated transport path" and a "regenerated carrier return path": the carrier to be generated is transported from the pyrolysis reactor 1 to the regeneration reactor 3 via the first flow sealing valve 2, and the regenerated carrier is transported back to the pyrolysis reactor 1 from the regeneration reactor 3 via the purge-desorption assembly 4, the second flow sealing valve 5, the riser 6, and the return inclined pipe 7; the first flow sealing valve 2 and the second flow sealing valve 5 are used to form a gas seal isolation, and the purge-desorption assembly is used to remove the regeneration side gas entrained in the regenerated carrier, thereby inhibiting the entry of regeneration side gases such as CO, CO2, and H2O into the pyrolysis side and preventing the backflow of pyrolysis side gas to the regeneration side, thus realizing the carrier circulation between the pyrolysis reactor 1 and the regeneration reactor 3 and suppressing gas crosstalk between the two sides.

[0034] A gas distribution plate is provided at the bottom of the cracking reactor 1. The gas distribution plate is connected to the inner wall of the cracking reactor 1. The bottom of the gas distribution plate is connected to the methane inlet pipe. A carrier replenishment port is provided at the bottom of the cracking reactor 1. The discharge section of the regeneration reactor 3 is equipped with a carbon discharge port 13, which is connected to the grading and screening end 14. The purge-desorption assembly 4 includes an inert purge chamber located in the transition cavity between the regenerated carrier outlet 17 and the second flow sealing valve 5 of the regeneration reactor 3. The inert purge chamber is connected to an inert gas pipeline. This design continuously or intermittently discharges a portion of the carbon product through the carbon discharge port 13, in conjunction with the replenishment of the circulating carrier through the carrier replenishment port. The carbon discharge product and circulating carrier replenishment strategy are linked to the deposited carbon removal ratio / carrier circulation volume to stabilize the system carbon inventory and prevent agglomeration and blockage. The purge-desorption assembly 4 removes CO / CO2 and other entrained substances from the carrier and directs them to the regeneration tail gas side. The carbon discharge port 13 is located on the discharge section of the regeneration reactor 3, which refers to the lower solid discharge area that the regenerated circulating carrier passes through before being discharged from the bottom of the regeneration reactor 3. The grading and screening end 14 is preferably a solid sorting unit located downstream of the carbon discharge port 13, used to sort the discharged carbon-containing solids and free carbon particles. The solid sorting unit, consisting of a sieving device, a cyclone classifier, and a sedimentation separation device, performs particle size and density classification. The classified solids can be output as carbon products and waste solids, respectively. The carbon products can be collected and recycled, while the waste solids can be further treated or discharged. Specifically, the gas introduced to the regeneration tail gas side is as follows: the purge desorption assembly 4 is equipped with a purge tail gas outlet. The CO, CO2, and H2O gases that are purged and stripped are mixed with the purge gas and discharged through this outlet. The purge tail gas is then incorporated into the regeneration tail gas side treatment channel through the purge tail gas branch. Since a second flow sealing valve 5 is installed downstream of the purge desorption assembly 4, the stripped gas will not enter the cracking side along the return path of the regenerated carrier, reducing the risk of impurities such as CO / CO2 / H2O entering the hydrogen production side.

[0035] Both the pyrolysis-side gas-solid separation unit 8 and the regeneration-side gas-solid separation unit 11 include a cyclone separator and a settling device. The settling device and the cyclone separator are connected in series. The input end of the settling device is connected to the pyrolysis gas outlet or the regeneration tail gas outlet, and the output end of the settling device is connected to the input end of the cyclone separator. A high-temperature filter 9 is connected to the cyclone separator of the pyrolysis side gas-solid separation unit 8, and the output end of the high-temperature filter 9 is connected to the hydrogen purification end 10. The output end of the cyclone separator in the regeneration-side gas-solid separation unit 11 is connected to the exhaust gas utilization treatment end 12. This design achieves fine dust removal through the cyclone separator, settling tank, and high-temperature filter 9 in the pyrolysis-side gas-solid separation unit 8, and through the cyclone separator and settling tank in the regeneration-side gas-solid separation unit 11. The exhaust gas utilization treatment end 12 is preferably located downstream of the regeneration-side gas-solid separation unit 11 and is used for energy recovery, component utilization, or purification of the regenerated exhaust gas. The regenerated exhaust gas mainly includes CO, CO2, H2, and H2O, and may contain a small amount of entrained dust. The exhaust gas utilization treatment unit includes a heat exchanger, waste heat recovery unit, cooling condenser, gas-liquid separator, dehydration unit, combustion treatment unit, and absorption / … The adsorption purification unit and syngas utilization unit, etc., can be used as fuel gas or syngas feedstock for further utilization, or can be discharged in compliance with standards after purification; the hydrogen purification end 10 is preferably set downstream of the high temperature filtration unit on the cracking side, and is used to remove impurities, separate and purify the cracking product gas. The cracking product gas mainly includes H2, unreacted CH4 and a small amount of light hydrocarbons and trace particulate impurities. The hydrogen purification unit adopts a combination of pressure swing adsorption device, membrane separation device and adsorption purification to obtain product hydrogen of target purity. Among them, the unreacted methane obtained by separation can be returned to cracking reactor 1 or used as fuel gas.

[0036] Cracking reactor 1 can be a bubble bed pyrolyzer, a circulating fluidized bed, or a riser reactor 6; The regeneration reactor 3 is a bubbling fluidized bed, circulating fluidized bed, or moving bed regenerator.

[0037] The regeneration reactor 3 is a moving bed regenerator with axial functional partitions. The moving bed regenerator includes a first regeneration zone and a second regeneration zone that are interconnected. The first regeneration zone is located at the upper part of the regeneration reactor 3, and the second regeneration zone is located at the lower part of the regeneration reactor 3. The first regeneration zone uses a low carbon removal ratio, while the second regeneration zone uses a high carbon removal ratio. Low and high carbon removal ratios are achieved by varying the regeneration medium flow rate, CO2 to water vapor volume ratio, zone temperature, and average residence time of the circulating carrier, respectively. This design utilizes a regeneration reactor 3, which is an existing moving bed or similar reactor capable of segmented operation. The innovation of this invention lies primarily in its "zonal operation mode and functional allocation." The regeneration reactor 3 is preferably a moving bed regenerator. The first and second regeneration zones do not necessarily correspond to two completely independent new devices; rather, they are preferably two functional zones arranged sequentially along the carrier movement direction within the same regeneration reactor 3. Each zone can achieve different carbon removal ratios through one or more of the following methods: axial zoning, segmented temperature control, segmented air intake, and segmented residence time, thereby realizing staged regeneration. With the first regeneration zone located at the top of the regeneration reactor 3 and the second regeneration zone at the bottom, the carbon-carrying circulating carrier self-regenerates... After entering from the top of reactor 3, the gas flows through the first and second regeneration zones sequentially before exiting from the bottom. The regeneration medium flows counter-currently from bottom to top through each regeneration zone. In the moving bed regenerator, solids typically move slowly downwards under gravity, while the gas typically contacts the solids counter-currently. Therefore, the use of upper and lower partitions allows for the formation of different carbon removal ratio zones within the same reactor. Preferably, the local carbon removal ratio in the first regeneration zone is controlled at 5%–30%, and in the second regeneration zone at 10%–50%. The total carbon removal ratio after accumulating the two zones is preferably controlled at 20%–70%, more preferably at 15%–65%, and even more preferably at 25%–55%. When the methane conversion rate on the cracking side remains stable and the bed pressure drop does not increase significantly, the carbon removal ratio is preferably controlled at 20%–40%. When the bed pressure drop increases, free carbon accumulation intensifies, or the methane conversion rate decreases, the carbon removal ratio can be temporarily increased to 40%–65%.

[0038] The first regeneration zone is located at the top of the regeneration reactor 3. It is mainly used for a relatively mild preliminary regeneration of the carbon-carrying circulating carrier, which preferentially removes loose carbon deposits on the outer surface, interparticle blockages, and some pore-deposited carbon, thereby restoring the main mass transfer channels and reducing the risk of local over-gasification in the subsequent carbon removal ratio regeneration stage. The second regeneration zone is located at the bottom of the regeneration reactor 3. It is mainly used to further remove residual carbon deposits at a higher carbon removal ratio and adjust the surface structure of the circulating carrier, restoring its pore structure, defect exposure degree, and surface oxygen-containing functional group state to the target window, thereby improving the methane activation capacity and cycle stability after returning to the cracking side.

[0039] Reference Figure 3The first regeneration zone and the second regeneration zone can be formed by one or more of the following methods: segmented temperature control, segmented air intake, segmented residence time control, or setting internal partition components. Preferably, the first regeneration zone adopts a lower carbon removal ratio and the second regeneration zone adopts a higher carbon removal ratio. The lower and higher carbon removal ratios can be achieved by different regeneration medium flow rates, CO2 to water vapor ratios, zone temperatures, and average residence times of the circulating carrier.

[0040] The regeneration medium inlet is divided into at least two gas distribution branches via an internal or external manifold of the moving bed regenerator. One gas distribution branch connects to the first gas distributor at the bottom, and the other connects to the second gas distributor in the lower middle section. Each gas distribution branch is equipped with a flow regulating component. This design, with a single regeneration medium inlet, allows the regeneration medium to enter from the main inlet at the bottom of the moving bed regenerator and then be divided into at least two gas distribution branches via an internal or external manifold. One branch connects to the first gas distributor at the bottom, and the other connects to the second gas distributor in the lower middle section. Each branch is equipped with a flow regulating component to achieve zoned gas supply to the first and second regeneration zones. Thus, although the moving bed regenerator has only one main inlet externally, different regeneration medium flow densities and compositions can be formed in different axial sections through the zoned gas distribution structure, thereby achieving regeneration environments of varying intensities. The flow regulating components are regulating valves, mass flow controllers, throttling elements, or combinations thereof, used to regulate the regeneration medium flow in the first and second gas distribution branches respectively, thereby creating zoned regeneration environments of different intensities.

[0041] Reference Figure 3 There are two regeneration medium inlets. One of the regeneration medium inlets is located at the bottom of the moving bed regenerator and connected to the first gas distributor at the bottom of the regenerator. It is used to supply the regeneration medium with high steam content or high flow rate to the second regeneration zone. Another regeneration medium inlet is located on the lower side wall of the moving bed regenerator and connected to the second gas distributor at its bottom. This inlet is used to supply the first regeneration zone with a regeneration medium that has a high CO2 content or a low flow rate. This design, through dual regeneration medium inlets, creates zoned environments with different carbon removal ratios in the upper and lower parts of the moving bed regenerator by adjusting the flow rate, composition, and zone temperature of the two inlets respectively.

[0042] The inert purge chamber includes a first purge-desorption chamber and a second purge-desorption chamber, which are arranged in series along the flow direction of the regenerated carrier. The first purge desorption chamber and the second purge desorption chamber are connected in series vertically by gravity. The regenerated carrier outlet 17 at the bottom of the regeneration reactor 3 is connected to the solid inlet at the top of the first purge desorption chamber. The solid outlet at the bottom of the first purge desorption chamber is connected to the solid inlet at the top of the second purge desorption chamber. The solid outlet at the bottom of the second purge desorption chamber is connected to the input end of the second flow sealing valve 5. The output end of the second flow sealing valve 5 is then connected to the lower end of the riser pipe 6, and the upper end of the riser pipe 6 is connected to the carrier return port 18 on the pyrolysis reactor 1 through the return inclined pipe 7. This design uses a closed first purge desorption chamber and a second purge desorption chamber, with a purge gas inlet and a purge tail gas outlet respectively. After regeneration, the carrier passes through the inert purge chamber in sequence. In the first purge desorption chamber, most of the entrained regeneration gas in the interparticle gaps and the weakly adsorbed gas on the outer surface are preferentially removed. In the second purge desorption chamber, the residual entrained gas and surface retained gas are further removed, thereby realizing a staged purge process of "first-stage coarse desorption and second-stage fine desorption". The two-stage purge tail gases are discharged from their respective tail gas outlets and are uniformly incorporated into the regeneration tail gas side for treatment.

[0043] Preferably, the first purge and desorption chamber uses a higher flow rate of purge gas to quickly replace the gas entrained between particles, and the second purge and desorption chamber uses a lower flow rate or cleaner purge gas to further reduce the concentration of residual CO, CO2 and H2O on the particle surface. The purge and desorption assembly 4 is used to reduce the concentration of regeneration side gas entrained with solids, while the second flow sealing valve 5 is used to block cross-flow caused by pressure difference between the two sides. The two work together to improve the gas isolation effect between the pyrolysis side and the regeneration side. The first and second purge-desorption chambers are independent units located downstream of the regeneration reactor 3. Their purge gas distribution components are independently configured and are not directly connected to the gas distribution plate inside the regeneration reactor 3. Preferably, the first purge-desorption chamber uses a higher flow rate of purge gas to quickly replace the regeneration side gas entrained in the interparticle gaps. The purge gas flow rate of the first purge-desorption chamber is preferably 0.20–0.60 Nm3 / h. The second purge-desorption chamber uses a lower flow rate and / or cleaner purge gas to further reduce the concentration of residual CO, CO2, and H2O on the particle surface and between particles. The purge gas flow rate of the second purge-desorption chamber is preferably 0.05–0.25 Nm3 / h.

[0044] Reference Figures 1-3 When continuous hydrogen production is required, the following is an example of the present invention: Example

[0045] When continuous hydrogen production is required using the equipment, the cracking reactor 1 is a bubbling bed cracking reactor, and the regeneration reactor 3 is a moving bed regeneration reactor. The circulating carrier is selected and pretreated, with granular activated carbon selected as the circulating carrier. The particle size is 150 μm, and the moisture content is <1 wt%. The activated carbon is pretreated at 800℃ for 2 hours under an inert atmosphere, such as N2, and then cooled and sealed for later use. The amount of solid bed material loaded into the bubbling bed cracking reactor is 2.0 kg.

[0046] The device operates continuously as follows: System inerting and heating: Close the upper and lower valves of the first flow sealing valve 2 and the second flow sealing valve 5, and introduce N2 into the pyrolysis side and the regeneration side respectively for inerting until the oxygen content at the pyrolysis side outlet is lower than the safety threshold (<0.5 vol%). Then heat the bubbling bed pyrolysis reactor and the moving bed regeneration reactor to the target temperature respectively.

[0047] Establishing the pyrolysis reaction: The bubbling bed pyrolysis reactor is stabilized at 900℃. Methane is introduced from the bottom gas distribution plate of the bubbling bed pyrolysis reactor, and the apparent gas velocity is controlled within the stable bubbling fluidization range. The pyrolysis product gas is discharged as product gas after being removed by the pyrolysis side gas-solid separation unit 8 and the high-temperature filter 9.

[0048] Establish a regeneration loop: The moving bed regeneration reactor is stabilized at 800℃. CO2 regeneration medium is introduced from the bottom of the moving bed regeneration reactor to form a countercurrent contact between the gas flowing from bottom to top and the carbon-carrying carrier flowing from top to bottom.

[0049] Solid cross-flow transfer: Close the lower valve of the first flow sealing valve 2 and open the upper valve to allow the carbon-carrying carrier from the bubbling bed pyrolysis reactor to enter the first flow sealing valve 2; After the loading is completed and the upper valve is closed, the inside of the first flow sealing valve 2 is subjected to differential pressure balance and inerting purging. CO2 or N2 can be used for purging. The purging exhaust gas is preferably incorporated into the tail gas treatment channel on the regeneration side. Then, the lower valve is opened to send the carrier to be generated into the moving bed regeneration reactor, realizing the loading-sealing-balancing / purging-discharging process. A stable circulating carrier throughput can be maintained through periodic or continuous lock hopper operation; by adjusting the feed amount per cycle, lock hopper cycle period, differential pressure balance time, and discharge time, the throughput of the carrier to be recycled entering the regeneration reactor 3 can be maintained stably.

[0050] Carrier return after regeneration: The bottom discharge from the moving bed regeneration reactor enters the purge and desorption assembly 4, and a small flow rate of N2 (1.0 Nm³) is introduced as purge gas. 3 / h, so that the CO / CO2 and other substances entrained in the carrier are stripped off and directed to the regeneration tail gas side; After purging, the carrier enters the second flow sealing valve 5 and is fed back into the bubbling bed pyrolysis reactor bed through the same "loading-sealing-balancing-discharging" steps as the first flow sealing valve 2.

[0051] Continuous carbon control / carbon discharge: Part of the carrier is led out from the waiting carrier branch and continuously discharged through the carbon discharge port 13 and enters the grading and screening end 14 for grading. The carbon products obtained from grading are collected. Fresh carrier can be added to the circulation loop at the same time to maintain the bed volume and mechanical properties.

[0052] The operating conditions are as follows: pyrolysis temperature 900℃, regeneration temperature 800℃, regeneration residence time 40 min, pyrolysis pressure 0.15 MPa, regeneration medium CO2, and regeneration medium flow rate 2.0 Nm³. 3 / h, the carbon removal rate is 40%.

[0053] Using the bed pressure drop ΔP / ΔP0 of the bubbling bed pyrolysis reactor as the stability criterion, the operation control and criteria are as follows: When the bed pressure drop ΔP / ΔP0 of cracking reactor 1 increases to 1.30 and the methane conversion rate in cracking reactor 1 is less than 96%, the proportion of deposited carbon removal is increased by 50%. When the bed pressure drop ΔP / ΔP0 of the cracking reactor 1 increases to 1.30 and the methane conversion rate is maintained at 96%, the solids removal ratio is increased by 10%, and the deposited carbon removal ratio is increased by 50% to suppress clogging and agglomeration. The CO / CO2 ratio in the regenerated exhaust gas is used as an indicator of the proportion of deposited carbon removed. When the CO to CO2 volume ratio at the regeneration tail gas outlet of regeneration reactor 3 is below 0.5 and the methane conversion rate is below 96%, it indicates insufficient regeneration. This can be addressed by increasing the CO2 flow rate of the regeneration medium to 2.6 Nm³. 3 / h or extend the regeneration residence time to 60 min to increase the deposition carbon removal rate to 50%; When the volume ratio of CO to CO2 at the regeneration tail gas outlet of regeneration reactor 3 is higher than 1.00 and the activity of the circulating carrier gradually decreases, the corresponding reduction of the deposited carbon removal ratio to 30% and the reduction of the solids discharge ratio to 0.5% indicate that the regeneration is too strong. The reduction of the deposited carbon removal ratio is necessary to avoid excessive gasification of the skeleton.

[0054] The results of Example 1 show that the method of the present invention can achieve a single-pass conversion rate of 96.7% for methane cracking, with a hydrogen purity of 99% in the product, indicating that the process has high methane conversion efficiency and excellent hydrogen separation effect. Meanwhile, the initial catalyst specific surface area was 729.96 m² / g, and the regenerated catalyst specific surface area was 723.19 m² / g, with a specific surface area retention rate of 99.07%, a decrease of only 0.93%. These results demonstrate that the present invention can effectively maintain the stability of the catalyst's main structure while efficiently and continuously producing hydrogen, avoiding significant over-gasification or ablation of the carbon skeleton. Example

[0055] The device is the same as in Example 1, except that the operating conditions, operation control, and criteria are changed as follows: The operating conditions are as follows: pyrolysis temperature 900℃, regeneration temperature 800℃, regeneration residence time 40 min, pyrolysis pressure 0.15 MPa, regeneration medium CO2, regeneration medium flow rate 2.0 Nm3 / h, and deposited carbon removal ratio 30%. Using the bed pressure drop ΔP / ΔP0 of the bubbling bed pyrolysis reactor as the stability criterion, the operation control and criteria are as follows: When the bed pressure drop ΔP / ΔP0 of pyrolysis reactor 1 increases to 1.1 and the methane conversion rate in pyrolysis reactor 1 is less than 96%, the proportion of deposited carbon removal is increased to 40%. When the bed pressure drop ΔP / ΔP0 of the cracking reactor 1 increases to 1.1 and the methane conversion rate is maintained at 96%, the solids removal ratio is increased by 10%, and the deposited carbon removal ratio is increased by 40% accordingly to suppress clogging and agglomeration. The CO / CO2 ratio in the regenerated exhaust gas is used as an indicator of the proportion of deposited carbon removed. When the CO to CO2 volume ratio at the regeneration tail gas outlet of regeneration reactor 3 is less than 0.5 and the methane conversion rate is less than 96%, it indicates insufficient regeneration. The deposition carbon removal ratio can be increased to 40% by increasing the CO2 flow rate of the regeneration medium to 2.6 Nm3 / h or extending the regeneration residence time to 60 min. When the volume ratio of CO to CO2 at the regeneration tail gas outlet of regeneration reactor 3 is higher than 1.00 and the activity of the circulating carrier gradually decreases, the corresponding reduction of the deposited carbon removal ratio to 20% and the reduction of the solids discharge ratio to 0.5% indicate that the regeneration is too strong. The reduction of the deposited carbon removal ratio is necessary to avoid excessive gasification of the skeleton.

[0056] The results of Example 2 show that the method of the present invention can achieve a single-pass conversion rate of 96.7% for methane cracking, with a hydrogen purity of 99% in the product, indicating that the process has high methane conversion efficiency and excellent hydrogen separation effect. Meanwhile, the initial catalyst specific surface area was 729.96 m² / g, and the regenerated catalyst specific surface area was 703.19 m² / g, with a specific surface area retention rate of 96.33%, a decrease of only 3.67%. These results demonstrate that this embodiment can maintain the stability of the catalyst's main structure while achieving efficient and continuous hydrogen production, avoiding significant over-gasification or ablation of the carbon skeleton. Example

[0057] The device is the same as in Example 1, except that the operating conditions, operation control, and criteria are changed as follows: The operating conditions are as follows: pyrolysis temperature 900℃, regeneration temperature 800℃, regeneration residence time 40 min, pyrolysis pressure 0.15 MPa, regeneration medium CO2, regeneration medium flow rate 2.0 Nm3 / h, and deposited carbon removal ratio 50%. Using the bed pressure drop ΔP / ΔP0 of the bubbling bed pyrolysis reactor as the stability criterion, the operation control and criteria are as follows: When the bed pressure drop ΔP / ΔP0 of cracking reactor 1 increases to 1.45 and the methane conversion rate in cracking reactor 1 is less than 96%, the proportion of deposited carbon removal is increased to 60%. When the bed pressure drop ΔP / ΔP0 of the cracking reactor 1 increases to 1.45 and the methane conversion rate is maintained at 96%, the solids removal ratio is increased by 10%, and the deposited carbon removal ratio is increased by 60% to suppress clogging and agglomeration. The CO / CO2 ratio in the regenerated exhaust gas is used as an indicator of the proportion of deposited carbon removed. When the CO to CO2 volume ratio at the regeneration tail gas outlet of regeneration reactor 3 is less than 0.5 and the methane conversion rate is less than 96%, it indicates insufficient regeneration. The deposition carbon removal ratio can be increased to 60% by increasing the CO2 flow rate of the regeneration medium to 2.6 Nm3 / h or extending the regeneration residence time to 60 min. When the volume ratio of CO to CO2 at the regeneration tail gas outlet of regeneration reactor 3 is higher than 1.00 and the activity of the circulating carrier gradually decreases, the corresponding reduction of the deposited carbon removal ratio to 40% and the reduction of the solids discharge ratio to 0.5% indicate that the regeneration is too strong. The reduction of the deposited carbon removal ratio is necessary to avoid excessive gasification of the skeleton.

[0058] The results of Example 3 show that the method of the present invention can achieve a single-pass conversion rate of 96.7% for methane cracking, with a hydrogen purity of 99% in the product, indicating that the process has high methane conversion efficiency and excellent hydrogen separation effect. Meanwhile, the initial catalyst specific surface area was 729.96 m² / g, and the regenerated catalyst specific surface area was 736.62 m² / g, an increase of approximately 0.91% compared to the initial value. These results demonstrate that this embodiment not only maintains the stability of the catalyst's main structure while achieving efficient and continuous hydrogen production, but also effectively restores the pores and active surfaces obscured by deposited carbon, avoiding significant over-gasification or ablation of the carbon skeleton.

[0059] In summary, Examples 1-3 demonstrate that under mild regeneration conditions with CO2 as the regeneration medium, the clogging carbon deposits on the surface of the carbon-carrying carrier can be effectively removed. The pressure drop in the pyrolysis reactor bed decreases significantly after regeneration, and the methane conversion rate recovers and re-enters the stable operating range. These results indicate that single-stage mild regeneration can effectively relieve some pore blockage and restore active sites, and no significant pulverization or instability of the circulating carrier was observed, indicating that the carbon skeleton did not undergo significant over-gasification. Example

[0060] The apparatus is the same as in Example 1, but the regeneration reactor 3 is replaced with a partitioned moving bed regenerator: it is divided into an upper first regeneration zone and a lower second regeneration zone along the height direction, and is equipped with two regeneration medium inlets or a single inlet + partitioned gas distribution structure to achieve regeneration environments of different intensities. The circulating carrier is selected and pretreated, and activated carbon / carbon black composite particles are selected as the circulating carrier: activated carbon is used as the skeleton, and 20wt% carbon black is added as a thermally conductive and defect site replenishing phase; it is used after pretreatment at 750℃ for 2h in N2 atmosphere, and the bed material of the pyrolysis reactor 1 is 2.0kg.

[0061] The device operates continuously as follows: (Same as in Example 1, except for the regeneration zone and the medium) Cracking reactor 1 is stabilized at 900℃, and CH4 is introduced from the bottom for cracking to produce hydrogen. Regeneration reactor 3 employs a combined CO2 and steam regeneration process. First regeneration zone: temperature 800℃, regeneration medium is mainly CO2, control the gasification rate to remove channel blockage, the first regeneration zone is the upper mild open zone; Preferably, the local carbon removal ratio in the first regeneration zone is controlled at 20%, which is used to preferentially remove loose carbon deposits on the outer surface, interparticle blockages, and some carbon deposits at the pore openings. Second regeneration zone: temperature 900℃, increase the proportion of water vapor to enhance gasification and active site regeneration, wherein the second regeneration zone is the lower structure recovery zone; The local carbon removal rate in the second regeneration zone is controlled at 20%, which is used to further remove residual carbon deposits and restore the pore structure and surface activity of the circulating carrier. The overall carbon removal rate after the two zones are accumulated is preferably controlled at 20%–70%, and more preferably at 30%–60%.

[0062] The volume ratio of CO2 to water vapor is 1:1, and the flow rate is adjusted by a steam flow valve.

[0063] The solid cross-flow transfer, purging, lock hopper return, and carbon discharge / feeding methods are the same as in Example 1.

[0064] The operation control and criteria are as follows: When the bed pressure drop ΔP / ΔP0 of cracking reactor 1 rises to 1.2 and the CO / CO2 volume ratio is low, below 0.6 and the methane conversion rate decreases, it indicates insufficient regeneration. The temperature of the second regeneration zone should be increased to 920℃ or the steam ratio should be increased. The CO / CO2 ratio in the regenerated exhaust gas is used as an indicator of the proportion of deposited carbon removed. When the bed pressure drop ΔP / ΔP0 is stable at 1-1.05, but the CO / CO2 ratio remains high, exceeding 1.2, and the performance of the circulating carrier declines, it indicates that the regeneration is too strong. The temperature of the second regeneration zone should be reduced to 700℃ or the steam ratio should be adjusted accordingly. By implementing a zoned regeneration process, the sequential control of "gentle opening followed by enhanced recovery" is achieved, enabling the circulating carrier to maintain a stable bed pressure drop and hydrogen production rate even after multiple cycles.

[0065] The results of Example 4 show that the method of the present invention can achieve a single-pass methane cracking conversion rate of 97.23% and a hydrogen purity of 99% in the product, indicating that the process has high methane conversion efficiency and excellent hydrogen separation effect. Meanwhile, the initial catalyst specific surface area was 1025.10 m² / g, and the regenerated catalyst specific surface area was 1003.19 m² / g, with a specific surface area retention rate of 97.86%, a decrease of only 2.14%. These results demonstrate that this embodiment can maintain the stability of the catalyst's main structure while achieving efficient and continuous hydrogen production, avoiding significant over-gasification or ablation of the carbon skeleton.

[0066] The zoned regeneration method is more effective than single-intensity regeneration in addressing both the needs of "de-clogging" and "preservation of the support structure." The first regeneration zone prioritizes the removal of deposited carbon on the outer surface and near the orifice, restoring the main mass transfer channels; the second regeneration zone further removes residual deposited carbon and improves the surface structure of the support. Through staged control, when the regenerated circulating support returns to the pyrolysis side, the methane conversion rate is restored more fully, the bed pressure drop fluctuation is smaller, and the main structure of the support is well preserved, indicating that zoned regeneration helps avoid localized excessive gasification and framework ablation. Example

[0067] The apparatus is the same as in Example 1, but without changing the principle of strict gas separation between the pyrolysis side and the regeneration side, the carrier return path is enhanced: the purge section of the purge desorption assembly 4 is designed as a two-stage series first purge desorption chamber and second purge desorption chamber, or the desorption efficiency is improved by extending the purge residence time, and a short-range "steady-state desorption section" is set before the second flow sealing valve 5 is added back to the bubbling bed pyrolysis reactor to further reduce the probability of entrained gas from the regeneration side entering the pyrolysis side; in addition, independent heating / heat exchange units can be configured in the bubbling bed pyrolysis reactor and the moving bed regeneration reactor respectively to maintain heat balance.

[0068] Taking K-promoted activated carbon as an example, the circulating carrier was prepared by selecting pretreated activated carbon with a particle size of 150 μm, preparing K2CO3 or KOH aqueous solution and introducing a small amount of alkali metal co-catalytic components by impregnation, so that the mass fraction of K element in the carbon-based material is 2wt%; after impregnation for 12 h, it was filtered, dried at 105℃, and then calcined at 850℃ for 3 h under N2 atmosphere to stabilize the K species and form a surface structure that is conducive to the initial activation of CH4. The resulting circulating carrier was loaded into the bubble bed pyrolysis reactor with a bed material amount of 2.0 kg.

[0069] The device operates continuously as follows: The temperature of the bubbling bed pyrolysis reactor was lowered to 850°C, and methane entered the pyrolysis reactor from the bottom; the moving bed regeneration reactor used a single CO2 regeneration medium and the regeneration temperature was 800°C.

[0070] The solid transporter transfer employs a dual-valve locking hopper method using a first flow sealing valve 2 and a second flow sealing valve 5. Each hopper cycle includes four steps: "loading - sealing - balancing / purging - discharging". The preferred purging gas is N2. After regeneration, the carrier is discharged in the purging and desorption assembly 4 at a concentration of 1.0 Nm³. 3 After being purged with inert gas at a rate of / h, the gas is then fed back into the bubble bed pyrolysis reactor via the second flow sealing valve 5.

[0071] In this embodiment, the carbon removal ratio is controlled by adjusting the CO2 flow rate, regeneration temperature, and average residence time of the carbon-carrying circulating carrier in the regenerator in the regeneration reactor 3.

[0072] The operating conditions are as follows: pyrolysis temperature 850℃, regeneration temperature 800℃, regeneration residence time 40 min, pyrolysis pressure 0.15 MPa, regeneration medium CO2, and regeneration medium flow rate 2.0 Nm³. 3 / h, the carbon removal rate is 40%.

[0073] Using the bed pressure drop ΔP / ΔP0 of the bubbling bed pyrolysis reactor as the stability criterion, the operation control and criteria are as follows: When the bed pressure drop ΔP / ΔP0 of pyrolysis reactor 1 increases to 1.30 and the methane conversion rate in pyrolysis reactor 1 is less than 96%, the proportion of deposited carbon removal is increased by 50%. When the bed pressure drop ΔP / ΔP0 of the cracking reactor 1 increases to 1.30 and the methane conversion rate is maintained at 96%, the solids removal ratio is increased by 10%, and the deposited carbon removal ratio is increased by 50% to suppress clogging and agglomeration. The CO / CO2 ratio in the regenerated exhaust gas is used as an indicator of the proportion of deposited carbon removed. When the CO to CO2 volume ratio at the regeneration tail gas outlet of regeneration reactor 3 is less than 0.5 and the methane conversion rate is less than 96%, it indicates insufficient regeneration. The deposition carbon removal ratio can be increased to 50% by increasing the CO2 flow rate of the regeneration medium to 2.6 Nm3 / h or extending the regeneration residence time to 60 min. When the volume ratio of CO to CO2 at the regeneration tail gas outlet of regeneration reactor 3 is higher than 1.00 and the activity of the circulating carrier gradually decreases, the corresponding reduction of the deposited carbon removal ratio to 30% and the reduction of the solids discharge ratio to 0.5% indicate that the regeneration is too strong. The reduction of the deposited carbon removal ratio is necessary to avoid excessive gasification of the skeleton.

[0074] The results of Example 5 show that the method of the present invention can achieve a single-pass methane cracking conversion rate of 97.04%, with a hydrogen purity of 99% in the product, indicating that the process has high methane conversion efficiency and excellent hydrogen separation effect. Meanwhile, the initial catalyst specific surface area was 523.25 m² / g, and the regenerated catalyst specific surface area was 523.19 m² / g, with a specific surface area retention rate of 99.99%, a decrease of only about 0.01%. These results demonstrate that this embodiment can maintain the stability of the catalyst's main structure while achieving efficient and continuous hydrogen production, avoiding significant over-gasification or ablation of the carbon skeleton.

[0075] In an alkali metal-promoted carbon-based circulating support system, a combination of two-stage purging-desorption and mild regeneration effectively reduces the risk of CO, CO2, and H2O entrained in the regenerated support entering the pyrolysis side. Furthermore, it maintains good activity recovery at a relatively low pyrolysis initiation temperature. No significant structural collapse or severe ablation was observed in the regenerated circulating support, indicating that this method promotes activity recovery while maintaining the stability of the circulating support's main structure.

[0076] To achieve long-term stable operation, the solids removal ratio is set to 10% based on the pressure drop ΔP / ΔP0 of the pyrolysis bed and the maintenance of the circulating carrier activity. Fresh carrier is added to maintain the bed material quantity and mechanical properties of the circulating carrier. The pyrolysis and regeneration sides are kept separate throughout the process. The pressure difference balance in the lock hopper and the purge gas are uniformly incorporated into the regeneration tail gas side for centralized treatment. The solids removal ratio is the proportion of the mass flow rate of solids discharged from the circulating solids loop per unit time to the total circulating solids flow rate, preferably controlled within the range of 0.1%–15%. During normal continuous operation, it is preferably 0.5%–2%. When the pyrolysis bed pressure drop increases, free carbon accumulation intensifies, or the methane conversion rate decreases, it can be temporarily increased to 5%–10%. In this embodiment, the solids removal ratio is 1% during normal operation and 10% during the enhanced emission stage. The pyrolysis and regeneration sides are kept separate throughout the process. The pressure difference balance in the lock hopper and the purge gas are uniformly incorporated into the regeneration tail gas side for centralized treatment.

[0077] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0078] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A continuous hydrogen production method for methane catalytic cracking based on a carbon-based circulating support, characterized in that, Includes the following steps: Carbon-based materials were selected as the circulating carriers and sent to the pyrolysis reactor (1). Methane is fed into the cracking reactor (1) and undergoes a cracking reaction with the circulating carrier under anaerobic conditions. The generated deposited carbon is at least partially deposited on the surface and in the pores of the circulating carrier, forming a carbon-carrying carrier. The gas produced by pyrolysis is drawn out from the outlet of the pyrolysis reactor (1), and after gas-solid separation, the carbon-carrying carrier is removed, and then the gas is subjected to fine dust removal to obtain low dust gas. The carbon-carrying carrier is introduced into the regeneration reactor (3); In the regeneration reactor (3), a regeneration medium is introduced to cause the deposited carbon on the carbon-carrying carrier to undergo a gasification reaction to obtain a regenerated carrier. The ratio of deposited carbon removal and the solids discharge ratio are adjusted to discharge the regeneration tail gas. The regenerated carrier is then returned to the pyrolysis reactor (1) to continue participating in the pyrolysis reaction.

2. The method for continuous hydrogen production from methane catalytic cracking based on a carbon-based circulating support according to claim 1, characterized in that, The regeneration reactor (3) is equipped with a carbon discharge port (13) in the discharge section for continuous or intermittent discharge of some carbon products.

3. The method for continuous hydrogen production from methane catalytic cracking based on a carbon-based circulating support according to claim 1, characterized in that, The circulating carrier includes one or more of activated carbon, carbon black, porous carbon, mesoporous carbon, carbon fiber, carbon felt, graphitized carbon, hard carbon-soft carbon composite material, and composite particles formed by coating carbon material onto an inert framework. The circulating carrier is in the form of powder, granules, spherical particles, honeycomb, or carrier coating. The particle size of the circulating carrier is 75-150 μm.

4. The method for continuous hydrogen production from methane catalytic cracking based on a carbon-based circulating support according to claim 3, characterized in that, The temperature of the pyrolysis reactor (1) is 850-1050℃ and the pressure is 0.1-0.4MPa; The temperature of the regeneration reactor (3) is 650-950℃.

5. The method for continuous hydrogen production from methane catalytic cracking based on a carbon-based circulating support according to claim 2, characterized in that, The regeneration medium includes one or both of CO2 and water vapor; When both coexist, the volume ratio of CO2 to water vapor is 0-10, where 0 indicates that the regeneration medium is only water vapor.

6. The method for continuous hydrogen production from methane catalytic cracking based on a carbon-based circulating support according to claim 5, characterized in that, The carbon removal rate of the deposited material is 20%-70%; When the reference bed pressure drop ΔP0 is established in the early stage of stable operation of the pyrolysis reactor (1), if the measured bed pressure drop ΔP of the pyrolysis reactor (1) during operation satisfies ΔP / ΔP0 = 1.05-1.50, it is determined that there is a trend of carbon deposition accumulation, and the carbon deposition removal ratio and solids discharge ratio are adjusted. The adjustment of the deposited carbon removal ratio and solids removal ratio includes the following steps: When the bed pressure drop ΔP / ΔP0 of the cracking reactor (1) increases to a preset threshold and the methane conversion rate in the cracking reactor (1) decreases, the proportion of deposited carbon removal is increased. When the bed pressure drop ΔP / ΔP0 of the cracking reactor (1) increases to the preset threshold and the methane conversion rate remains within the preset stable range, the solids discharge ratio is increased and the carbon removal ratio is increased accordingly. When the CO to CO2 volume ratio at the regeneration tail gas outlet of the regeneration reactor (3) is lower than the set value and the methane conversion rate decreases, the carbon removal ratio can be increased by one or more of the following methods: increasing the regeneration medium flow rate, increasing the regeneration steam ratio, increasing the regeneration temperature, and extending the regeneration residence time. When the volume ratio of CO to CO2 at the outlet of the regeneration tail gas of the regeneration reactor (3) is higher than the set value and the activity of the circulating carrier gradually decreases, the proportion of deposited carbon removal and the solids discharge ratio are reduced accordingly. The solids removal ratio is defined as the proportion of the mass of solid carbon separated and recovered as a product to the total mass of solid carbon generated from methane cracking within the same statistical period, with a solids removal ratio of 0.1%–15%.

7. An apparatus for implementing the continuous hydrogen production method for methane catalytic cracking based on a carbon-based circulating support as described in claim 1, characterized in that, It includes a pyrolysis reactor (1), a regeneration reactor (3), a pyrolysis-side gas-solid separation unit (8), and a regeneration-side gas-solid separation unit (11). The top of the pyrolysis reactor (1) is provided with a pyrolysis gas outlet, which is connected to the pyrolysis-side gas-solid separation unit (8). The pyrolysis reactor (1) is provided with a pyrolysis-side carrier discharge port (15) at the bottom, the regeneration reactor (3) is provided with a regeneration-side carrier inlet (16) and a regeneration tail gas outlet at the top, and the regeneration reactor (3) is provided with a regeneration medium inlet and a solid discharge port at the bottom. A sealed return and carrier circulation unit is provided between the pyrolysis-side waiting carrier discharge port (15) and the regeneration-side waiting carrier inlet (16) at the top of the regeneration reactor (3), and between the regenerated carrier discharge port (17) at the bottom of the regeneration reactor (3) and the carrier return port (18) on the pyrolysis reactor (1). The regenerated exhaust gas outlet is connected to the regenerated side gas-solid separation unit (11).

8. The apparatus for continuous hydrogen production from methane via catalytic cracking based on a carbon-based circulating support according to claim 7, characterized in that, The sealed return and carrier circulation unit includes a first flow sealing valve (2), a purge desorption assembly (4), a second flow sealing valve (5), a riser pipe (6), and a return inclined pipe (7). The pyrolysis-side carrier discharge port (15) is connected to the regeneration-side carrier inlet (16) at the top of the regeneration reactor (3) via the first flow sealing valve (2). The regenerated carrier outlet (17) at the bottom of the regeneration reactor (3) is connected to the carrier return port (18) of the pyrolysis reactor (1) via the purge and desorption assembly (4), the second flow sealing valve (5), the riser (6), and the return inclined pipe (7).

9. The apparatus for continuous hydrogen production from methane catalytic cracking based on a carbon-based circulating support according to claim 8, characterized in that, The bottom of the pyrolysis reactor (1) is provided with a gas distribution plate, which is connected to the inner wall of the pyrolysis reactor (1), and the bottom of the gas distribution plate is connected to the methane inlet pipe. The regeneration reactor (3) is provided with a carbon discharge port (13) on the discharge section, and the carbon discharge port (13) is connected to the grading and screening end (14). The purge and desorption assembly (4) includes an inert purge chamber disposed on the transition cavity between the regenerated carrier outlet (17) and the second flow sealing valve (5) of the regeneration reactor (3), the inert purge chamber being connected to a pipeline of inert gas.

10. The apparatus for continuous hydrogen production from methane catalytic cracking based on a carbon-based circulating support according to claim 8, characterized in that, Both the pyrolysis-side gas-solid separation unit (8) and the regeneration-side gas-solid separation unit (11) include a cyclone separator and a settling device; The settling device is connected in series with the cyclone separator. The input end of the settling device is connected to the pyrolysis gas outlet or the regeneration tail gas outlet, and the output end of the settling device is connected to the input end of the cyclone separator. The cyclone separator of the pyrolysis side gas-solid separation unit (8) is connected to a high-temperature filter (9), and the output end of the high-temperature filter (9) is connected to a hydrogen purification end (10). The output end of the cyclone separator of the regeneration side gas-solid separation unit (11) is connected to the exhaust gas utilization treatment end (12).

11. The apparatus for continuous hydrogen production from methane via catalytic cracking based on a carbon-based circulating support according to claim 9, characterized in that, The pyrolysis reactor (1) is a bubble bed pyrolyzer, a circulating fluidized bed, or a riser (6) reactor; The regeneration reactor (3) is a bubbling fluidized bed, a circulating fluidized bed, or a moving bed regenerator.

12. The apparatus for continuous hydrogen production from methane via catalytic cracking based on a carbon-based circulating support according to claim 11, characterized in that, The regeneration reactor (3) is a moving bed regenerator with axial functional partitions. The moving bed regenerator includes a first regeneration zone and a second regeneration zone that are interconnected. The first regeneration zone is located at the upper part of the regeneration reactor (3), and the second regeneration zone is located at the lower part of the regeneration reactor (3).

13. The apparatus for continuous hydrogen production from methane via catalytic cracking based on a carbon-based circulating support according to claim 12, characterized in that, The regeneration medium inlet is divided into at least two gas distribution branches via an internal or external manifold of the moving bed regenerator. One gas distribution branch is connected to the first gas distributor at its bottom, and the other gas distribution branch is connected to the second gas distributor at its lower part. Each of the two gas distribution branches is equipped with a flow regulating component.

14. The apparatus for continuous hydrogen production from methane via catalytic cracking based on a carbon-based circulating support according to claim 12, characterized in that, The regeneration medium inlet is provided in two places, one of which is located at the bottom of the moving bed regenerator and connected to the first gas distributor at the bottom of it; Another regeneration medium inlet is located on the lower side wall of the moving bed regenerator and connected to the second gas distributor at its bottom.

15. The apparatus for continuous hydrogen production from methane via catalytic cracking based on a carbon-based circulating support according to claim 9, characterized in that, The inert purge chamber includes a first purge-desorption chamber and a second purge-desorption chamber, which are arranged in series along the flow direction of the regenerated carrier. The first purge desorption chamber and the second purge desorption chamber are connected in series vertically by gravity. The regenerated carrier outlet (17) at the bottom of the regeneration reactor (3) is connected to the solid inlet at the top of the first purge desorption chamber. The solid outlet at the bottom of the first purge desorption chamber is connected to the solid inlet at the top of the second purge desorption chamber. The solid outlet at the bottom of the second purge desorption chamber is connected to the input end of the second flow sealing valve (5). The output end of the second flow sealing valve (5) is then connected to the lower end of the riser pipe (6), and the upper end of the riser pipe (6) is connected to the carrier return port (18) on the pyrolysis reactor (1) through the return inclined pipe (7).

Images