Method for producing hydrogen by intensifying ammonia decomposition through cooperation of plasma and double-membrane reactor

Abstract

The invention discloses a method for producing hydrogen through plasma synergistic double-membrane enhanced ammonia decomposition, and belongs to the technical field of hydrogen energy. According to the method, in a plasma catalytic reactor integrated with a hydrogen separation membrane, efficient decomposition of ammonia is achieved within the temperature range of 100-500 DEG C by means of the synergistic effect of low-temperature plasma and an efficient catalyst, and the catalyst comprises at least one metal active component. Hydrogen generated in the reaction is separated in situ, so that the equilibrium limitation of the reaction is broken, and the conversion per pass is remarkably improved. And the tail gas of the reactor is further treated by a downstream multi-stage ammonia recovery membrane system (such as an ammonia selective molecular sieve membrane), so that high-efficiency and low-energy-consumption recovery and cyclic utilization of the unreacted ammonia are realized. According to the invention, the problems of high temperature, large energy consumption, limited conversion rate and the like of the traditional ammonia decomposition process are solved, and an efficient, energy-saving and environment-friendly technical scheme is provided for constructing a sustainable ammonia-hydrogen energy system.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy technology, specifically relating to a method for enhancing ammonia decomposition to produce hydrogen using a plasma-assisted dual-membrane reactor, and more particularly to a method for efficiently producing hydrogen from ammonia by utilizing the synergistic effect of low-temperature plasma, a high-efficiency catalyst, and a dual-membrane system. Background Technology

[0002] Hydrogen (H2) is considered a core component of future sustainable energy systems due to its clean and efficient properties. However, the cryogenic liquefaction storage and long-distance transportation of hydrogen face significant technological challenges and high economic costs, hindering the development of a hydrogen economy. Against this backdrop, ammonia (NH3), as a carbon-free hydrogen carrier, has attracted considerable attention due to its advantages, including high hydrogen storage density (17.6 wt%), mild liquefaction conditions, and well-developed global infrastructure. Therefore, developing efficient and low-carbon ammonia decomposition technologies is crucial for building an "ammonia-hydrogen economy."

[0003] Traditional ammonia decomposition technology mainly relies on thermocatalysis, but this method has inherent drawbacks. First, due to the kinetic limitations of the ammonia decomposition reaction, it typically needs to be carried out at high temperatures (>550°C), which not only leads to huge energy consumption and significant carbon emissions but also causes catalyst sintering and deactivation. Second, the reaction is reversible and limited by thermodynamic equilibrium; even at high temperatures, the single-pass conversion rate is difficult to achieve ideal levels, and the product hydrogen gas has an inhibitory effect on the reaction. To handle the large amount of unreacted ammonia in the tail gas, a cryogenic separation and recovery unit with extremely high energy consumption must be equipped, which seriously reduces the economic feasibility of this route.

[0004] Nonthermal plasma (NTP) technology provides a new approach for activating molecules at low temperatures. High-energy electrons (1-10 eV) in plasma can directly excite and dissociate NH3 molecules under mild conditions. A study published in Int. J. EnergyRes 2022, 46(3), 3572-3587 further evaluated the performance of hydrogen separation using Pd-Cu membranes in a catalytic plasma membrane reactor, finding that the synergistic effect of plasma and zeolite catalyst (SA-600A) can significantly improve hydrogen permeability. However, most of these studies remain at the level of simple combination of discrete devices, failing to achieve deep coupling between the reactor and the catalyst, especially lacking high-performance catalysts specifically designed for plasma environments. Therefore, there is still considerable room for improvement in the overall conversion efficiency and energy efficiency of the system. In particular, the "Debye shielding effect" that is prevalent in porous catalysts, i.e., the difficulty of plasma penetrating deep into the nanopores of the catalyst, makes it impossible to effectively utilize most active sites. This is a fundamental challenge facing plasma catalysis, and existing research has not provided an effective solution.

[0005] Furthermore, most existing studies focus on maximizing the single-pass conversion rate of the reactor, neglecting the construction of ultra-low-energy closed-loop systems by combining with efficient separation technologies to achieve higher atom economy and process sustainability. For example, the system reported in the published paper "IJHE 2019, 44(20), 9987-9993" combines a catalytic reactor with a plasma membrane reactor (PMR). Although it successfully obtained high-purity hydrogen, its process flow is still relatively complex, and the recovery and utilization of unreacted ammonia in the tail gas has not been optimized. A large amount of unreacted ammonia still needs to be processed in high-energy-consuming downstream separation units (such as cryogenic separation), which greatly increases the system complexity and operating costs, and reduces the overall economic efficiency.

[0006] Therefore, there is an urgent need to develop a new ammonia decomposition hydrogen production technology that can operate under mild conditions and integrates efficient reaction, in-situ product separation, and low-energy recovery of raw materials. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a plasma-coordinated dual-membrane enhanced ammonia decomposition method for hydrogen production, which aims to achieve efficient ammonia conversion, online hydrogen separation, and low-energy closed-loop recycling of unreacted ammonia under mild conditions.

[0008] Technical Principle: This invention deeply couples and integrates dielectric barrier discharge (DBD) plasma technology, a catalyst specifically designed for the plasma environment, and two membrane separation technologies with different functions. First, inside the reactor, high-energy electrons and active species generated by the low-temperature plasma activate ammonia molecules at a lower temperature and synergistically interact with the catalyst surface to accelerate ammonia decomposition. Simultaneously, the first type of membrane (hydrogen separation membrane) integrated within the reactor selectively and in real time removes the product hydrogen from the reaction zone, continuously shifting the reaction equilibrium towards a direction favorable to product formation, thereby significantly improving the single-pass conversion rate. The exhaust gas from the reactor then enters a separation system composed of the second type of membrane (ammonia selective permeation membrane). This membrane has excellent selectivity for ammonia, enabling efficient recovery of gaseous ammonia at room temperature and direct recycling, avoiding the high energy consumption of traditional cryogenic separation.

[0009] The technical solution of the present invention is as follows: A method for enhancing ammonia decomposition to produce hydrogen using a plasma-coordinated dual-membrane reactor includes the following steps: introducing ammonia-containing feed gas into a plasma catalytic reactor integrated with a hydrogen separation membrane; generating low-temperature plasma by applying an electric field within the plasma catalytic reactor, and carrying out an ammonia decomposition reaction under the action of a catalyst, thereby decomposing ammonia into hydrogen and nitrogen in one step; during the reaction, the generated hydrogen is separated in situ and exported through the hydrogen separation membrane; the catalyst contains at least one metallic active component.

[0010] It also includes passing tail gas containing unreacted ammonia, nitrogen, and hydrogen into an ammonia recovery membrane separation system to separate and recover the unreacted ammonia.

[0011] The plasma is a dielectric barrier discharge plasma.

[0012] The plasma catalytic reactor provides a reaction temperature of 100-500 °C, preferably 350-450 °C. The reaction pressure is atmospheric pressure.

[0013] The active metal component includes one or more of Ru, Ni, Fe, Co, Pt, and Pd.

[0014] The catalyst is a conventional catalyst in the art, including supported catalysts or unsupported catalysts (such as metal mesh and / or metal foam); preferably, the catalyst is a supported catalyst. Further, the metal active component is distributed in the form of nanoparticles on the outer surface of the support. Even further, the supported catalyst is prepared by atomic layer deposition (ALD), such as a Ru / SiO2 catalyst, or by other preparation methods that enable the active component to be preferentially distributed on the outer surface of the catalyst. This method makes the metal active component highly dispersed in the form of nanoparticles on the outer surface of the support, so as to effectively overcome the Debye shielding effect of plasma.

[0015] The hydrogen separation membrane is a hydrogen selective permeation membrane known in the art, including a metal membrane, a molecular sieve membrane, or a polymer membrane. The plasma catalytic reactor is a coaxial dielectric barrier discharge reactor, and its dielectric tube is composed of a porous ceramic substrate. The hydrogen separation membrane is loaded on the inner or outer surface of the porous ceramic substrate. The dielectric tube is filled with a catalyst and is equipped with a high-voltage electrode and a grounding electrode.

[0016] The thickness of the hydrogen separation membrane is ≤2μm.

[0017] The ammonia recovery membrane separation system uses an ammonia-selective permeation membrane, including a zeolite membrane, a polymer membrane, or a mixed matrix membrane. Preferably, the ammonia recovery membrane is an ammonia-selective molecular sieve membrane, and more preferably, the ammonia recovery membrane is a MIF molecular sieve membrane.

[0018] The ammonia recovered by the ammonia recovery membrane separation system is recycled as raw material gas.

[0019] The plasma reactor tail gas outlet is connected to an ammonia recovery membrane separation system, which includes at least two membrane modules connected in series.

[0020] The membrane assembly includes a porous ceramic substrate, with an ammonia-selective permeation membrane loaded on the outside of the porous ceramic substrate and placed inside a metal casing.

[0021] The plasma catalytic reactor further includes a quartz tube as the outer shell, a porous ceramic substrate being a porous α-Al2O3 tube coaxially disposed inside the quartz tube, a high-voltage electrode inserted and fixed in the central channel of the porous α-Al2O3 tube, a grounding electrode wound around the outer wall of the porous α-Al2O3 tube, a hydrogen separation membrane loaded on the inner wall of the porous α-Al2O3 tube, and a catalyst filling the annular region between the high-voltage electrode and the hydrogen separation membrane.

[0022] The beneficial effects of this invention are as follows: 1. Mild reaction conditions and significantly reduced energy consumption: Through the synergistic effect of plasma and catalyst, the high temperature (>550 ℃) required for traditional ammonia decomposition is reduced to 100-500 ℃, and it can operate efficiently under the preferred mild conditions of 350-450 ℃, which significantly reduces heating energy consumption and related carbon emissions.

[0023] 2. Overcoming equilibrium limitations and achieving high conversion efficiency: By integrating a hydrogen separation membrane into the reactor, the product H2 is removed in situ, effectively overcoming the thermodynamic equilibrium limitations and significantly improving the single-pass conversion rate of NH3 (in the preferred example, the relative improvement is 24.8%).

[0024] 3. Energy-saving raw material recovery and sustainable process: The high-efficiency S-1 zeolite membrane is used to recover NH3 in the exhaust gas, realizing direct gas phase circulation at normal temperature and pressure, avoiding the high compression and phase change energy costs required by traditional cryogenic separation, and realizing closed-loop utilization of raw materials.

[0025] 4. High system integration, combining reaction, separation and recovery functions in a compact manner, reducing equipment complexity and energy consumption: Integrating the three major functions of reaction, product separation and raw material recovery into a compact system demonstrates a high degree of systems engineering innovation and provides an economical, feasible and environmentally friendly new technical route for ammonia-to-hydrogen production. Attached Figure Description

[0026] Figure 1 These are HAADF-STEM images and particle size distribution diagrams of the ALD-Ru / SiO2 catalyst used in this invention and the Im-Ru / SiO2 catalyst prepared by the impregnation method.

[0027] Figure 2 This is a scanning electron microscope (SEM) image of the S-1 zeolite membrane used in this invention.

[0028] Figure 3 This is a schematic diagram of the structure of the plasma-enhanced dual-membrane ammonia decomposition system (PEDMADS) proposed in this invention.

[0029] Figure 4This is a schematic cross-sectional view of the internal structure of the plasma catalytic reactor used in this invention.

[0030] Figure 5 This is a photograph of the plasma-membrane coupled catalytic device (plasma membrane catalytic reactor) in this invention.

[0031] Figure 6 This is a comparison chart of the ammonia decomposition performance of different catalysts under plasma conditions in this invention.

[0032] Figure 7 This is a comparison chart of the ammonia decomposition performance of the present invention under different operating conditions, used to demonstrate the synergistic effect of plasma and Pd film.

[0033] Figure 8 This is a graph showing the performance relationship of the integrated system of this invention at different reaction temperatures.

[0034] Figure 9 This is a performance relationship diagram of the integrated system of the present invention under different raw material gas flow rates.

[0035] Figure 10 This is a graph showing the permeation performance of the Pd membrane prepared in this invention at 400 °C in a mixed gas.

[0036] Figure 11 This is a graph showing the separation performance of the S-1 membrane under different NH3 feed concentrations in this invention.

[0037] Figure 12 This is a schematic diagram of the five-stage S-1 membrane cascade system used in this invention for NH3 recovery, and the changes in NH3 concentration at each stage; Among them, 1 is the high-voltage electrode, 2 is the palladium film, 3 is the graphite sealing ring, 4 is the grounding electrode, 5 is the quartz tube, 6 is the porous α-Al2O3 tube, and 7 is the catalyst. Detailed Implementation

[0038] Example 1: Preparation of ALD-Ru / SiO2 catalyst This embodiment relates to the preparation of a high-efficiency plasma catalyst. The catalyst ALD-Ru / SiO2 was prepared in a commercial ALD reactor (MCRI FH-2). Ruthenium dicene (Ru(Cp)2) was used as the ruthenium precursor, and O2 was used as the reactant gas. The Ru(Cp)2 precursor source bottle was maintained at 60-100 °C, and deposition was carried out on a SiO2 support at a reaction chamber temperature of 300 °C. High-purity N2 was used as the carrier gas and purge gas. One ALD cycle consisted of: a 10-second Ru(Cp)2 pulse, a 30-second N2 purge, a 10-second O2 pulse, and a final 30-second N2 purge. Multiple ALD cycles were performed throughout the deposition process until the target catalyst loading was obtained. The prepared catalyst was characterized (e.g., ...). Figure 1As shown in the figure, the Ru nanoparticles have an average particle size of 1.56 ± 0.04 nm and exhibit an ultrafine and uniformly dispersed state on the carrier.

[0039] Example 2: Preparation of catalyst (Im-Ru / SiO2) by impregnation method 102 mg of ruthenium nitrite (III) was dissolved in 5 mL of deionized water and added dropwise to 5 g of fumed silica support. The solution was aged at room temperature for 12 hours, then dried overnight at 120 °C, and calcined in a muffle furnace at 400 °C for 4 hours. The catalyst was finally crushed and sieved to 20-40 mesh for later use. The obtained catalyst was characterized (e.g., ...). Figure 1 As shown in the figure, the average particle size of Ru nanoparticles is 2.12 ± 0.07 nm.

[0040] Table 1: Physicochemical properties of catalysts and supports a The BET method is adopted. b Total adsorption amount when P / P0=0.99. c Determined by the t-plot method. d V total - V micro。 e The BJH method was adopted. f Measured by ICP-OES.

[0041] Example 3: Preparation of ultrathin Pd films and S-1 zeolite films This embodiment involves the preparation of two key membranes in the system. (1) Preparation of ultrathin Pd film: A Pd film was prepared on a porous α-Al2O3 tube inner wall substrate (50 mm long, 12 mm outer diameter, 8 mm inner diameter) by electroless plating. The process included substrate pretreatment, surface activation, and metal deposition. The activation step was completed by immersing the substrate in an acidic stannous chloride sensitizing solution and an acidic palladium chloride activation solution. Finally, the activated substrate was immersed in an electroless plating solution containing palladium salt, hydrazine hydrate (reducing agent), and EDTA (complexing agent) for 20 minutes until a continuous and dense Pd layer was formed. The obtained Pd film was approximately 1.8 μm thick, with a dense surface and no defects.

[0042] (2) Preparation of S-1 zeolite film: S-1 film was prepared on the outer surface of porous α-Al2O3 tube substrate by a secondary growth method. First, a self-supporting five-membered ring (SPP) zeolite seed layer was coated on the substrate by dip-coating. Then, the substrate with the seed layer was placed in a precursor solution with a chemical composition of 1 TEOS: 0.15 TPAOH: 140 H2O and crystallized at 130℃ for 2 hours under single-mode microwave heating. Finally, the template agent was removed by washing, drying and ozone calcination to obtain a high-quality S-1 film. The obtained S-1 film has a thickness of about 900 nm and exhibits a highly preferred orientation (h0h) (e.g. Figure 2 (As shown). Gas permeation tests showed that the membrane had a separation factor of up to 686 for NH3 / H2 (70:30 mixture) at 25°C and 1 bar.

[0043] Example 4: Preparation of Pd films of different thicknesses The Pd film was prepared using the exact same steps as in Example 3(1), except that the deposition time in the chemical plating solution was extended to 60 minutes. The resulting Pd film had a dense and defect-free surface, but its thickness was measured to be approximately 5.2 μm, which was significantly thicker than the film prepared in Example 3(1).

[0044] Example 5: Construction of an integrated system (Construction of a plasma-enhanced two-membrane ammonia decomposition system) like Figure 3-5 As shown, the plasma-enhanced dual-membrane ammonia decomposition system includes a plasma catalytic reactor and an ammonia recovery membrane separation system. The plasma catalytic reactor includes a quartz tube 5 as the outer shell. A porous α-Al2O3 tube 6 with a Pd-coated membrane 2 obtained in Example 3 (1) or Example 4 is coaxially arranged inside the quartz tube 5. A high-voltage electrode 1 is inserted and fixed in the central channel of the porous α-Al2O3 tube 6. A grounding electrode 4 is wound around the outer wall of the porous α-Al2O3 tube 6. The catalyst 7 described in Example 1 is filled in the annular area between the high-voltage electrode and the porous α-Al2O3 tube. Graphite sealing rings at both ends of the plasma catalytic reactor are placed between the quartz tube and the porous α-Al2O3 tube. The tail gas outlet of the plasma reactor is connected to the ammonia recovery membrane separation system. The ammonia recovery membrane separation system includes five membrane modules connected in series. The membrane module includes a porous α-Al2O3 tube containing an S-1 zeolite membrane prepared in Example 3 (2), which is placed inside a metal membrane module (metal shell). The quartz tube 5 includes a lower raw material inlet, a purge gas inlet on the same side as the raw material inlet, and an upper H2 permeation outlet.

[0045] Inside the plasma catalytic reactor, a low-temperature plasma is generated by applying an electric field, and ammonia is decomposed into hydrogen and nitrogen under the action of a catalyst. During the reaction, the generated hydrogen is separated in situ through the Pd membrane 2 and discharged through the H2 permeation outlet of the quartz tube 5 in the outer shell. The tail gas containing unreacted ammonia, nitrogen and hydrogen is introduced into the ammonia recovery membrane separation system to separate and recover the unreacted ammonia.

[0046] Example 6: Comparative Test of Basic Performance of Different Catalysts To verify the effect of different preparation methods on catalyst activity in Examples 1 and 2, 0.5 g each of the two catalysts (ALD-Ru / SiO2 and Im-Ru / SiO2) were loaded into plasma reactors without Pd membranes (the plasma catalytic reactor described in Example 5, but without Pd membranes), and their reaction activity was tested under conditions of 400°C and 300 mL / min pure NH3 feed. Control groups consisting of pure plasma and pure SiO2 support were also set up. The test results are as follows: Figure 6 As shown in the figure, the NH3 conversion rate of the ALD-Ru / SiO2 catalyst reaches 52.1%, significantly higher than the 41.2% of the Im-Ru / SiO2 catalyst, and far superior to the control groups of pure SiO2 support (5.6%) and pure plasma (3.9%). This demonstrates the superiority of the ALD preparation method used in this invention in improving plasma catalytic activity. This is attributed to the catalyst prepared by the ALD method (Example 1, as shown in the figure). Figure 1 As shown in the figure, its active components are mainly distributed on the outer surface of the carrier, which effectively overcomes the "Debye shielding effect" mentioned in the background technology, allowing the active sites to fully contact the plasma.

[0047] Example 7: Effect of different catalyst loading amounts on performance To investigate the effect of catalyst loading, 0.25 g, 0.5 g, and 1.0 g of the ALD-Ru / SiO2 catalyst prepared in Example 1 were weighed and loaded into a plasma reactor without a Pd membrane (the plasma catalytic reactor described in Example 5, but without a Pd membrane). Reaction activity was tested under the same conditions as in Example 6 (400 °C, 300 mL / min pure NH3). The test results showed that with a loading of 0.25 g, the NH3 conversion rate was 40.5%. With a loading of 0.5 g, the NH3 conversion rate was 52.1%. With a loading of 1.0 g, the NH3 conversion rate was 55.3%. The results indicate that increasing the catalyst loading can improve the NH3 conversion rate, but the efficiency per unit mass of catalyst (space-time yield) decreases. Considering both reaction performance and catalyst dosage, 0.5 g is a preferred loading amount for this reactor structure.

[0048] Example 8: Ammonia decomposition performance test of plasma catalytic reactor This embodiment verifies the core synergistic effect of the plasma catalytic reactor of the present invention. Using the plasma catalytic reactor constructed in Example 5 (loaded with 0.5 g of the ALD-Ru / SiO2 catalyst from Example 1), the performance was compared under four different operating conditions at an NH3 feed rate of 300 mL / min and a reaction temperature of 400 °C. The results are as follows: Figure 7 As shown, the NH3 conversion rate of pure thermal catalysis (without plasma or Pd membrane) was only 9.6%. Under plasma catalysis (without Pd membrane), the conversion rate increased significantly to 52.1%, with a hydrogen production space-time yield (STY) of 1256 mmol g. -1 h -1 Furthermore, the integrated system combining plasma catalysis and in-situ Pd membrane separation employed in this invention further boosts the NH3 conversion rate to 65.0%, achieving a hydrogen production space-time yield (STY) of 1567 mmol g. -1 h -1 These results clearly demonstrate a synergistic enhancement effect between "plasma" and "in-situ separation of Pd membrane" in this invention.

[0049] Example 9: Performance Study of Plasma Catalytic Reactor at Different Reaction Temperatures Using the plasma catalytic reactor constructed in Example 5 (employing a 1.8 μm Pd membrane and 0.5 g of ALD-Ru / SiO2 prepared in Example 1), the effect of different reaction temperatures on system performance was investigated at an NH3 flow rate of 300 mL / min. The results are as follows: Figure 8 As shown, when the reaction temperature was increased from 380℃ to 440℃ by adjusting the discharge power, the conversion rate of NH3 significantly increased from about 55% to about 92%. Furthermore, the effects of three temperature points—150℃, 300℃, and 450℃—on the system performance were investigated. At 150℃, the NH3 conversion rate was 10.2%; at 300℃, it was 31.5%; and at 450℃, it was 93.1%. These results indicate that the system of this invention can operate over a wide temperature range of 100-500℃, and achieves extremely high conversion rates within the preferred range of 350-450℃.

[0050] Example 10: Performance Study of Plasma Catalytic Reactor under Different Feed Gas Flow Rates At a reaction temperature of 400°C, the effect of different NH3 feed flow rates on system performance was investigated using the plasma catalytic reactor constructed in Example 5 (employing a 1.8 μm Pd membrane and 0.5 g of ALD-Ru / SiO2 prepared in Example 1). The results are as follows: Figure 9As shown, when the NH3 feed flow rate increased from 150 mL / min to 500 mL / min, the single-pass conversion of NH3 decreased from approximately 82% to approximately 48%. However, the overall space-time yield (STY) of hydrogen production increased from approximately 980 mmol g / L. -1 h -1 Increased to approximately 1920 mmol g -1 h -1 This demonstrates that the system of the present invention can flexibly balance conversion rate and yield by adjusting the flow rate.

[0051] Example 11: Permeation performance test of Pd membrane To verify the effectiveness of the hydrogen separation membrane used in this invention, the gas permeation performance of the ultrathin Pd membrane (1.8 μm) prepared in Example 3 (1) was tested at 400 °C with an equimolar mixture of H2 / NH3 / N2 as feed. The test results are as follows: Figure 10 As shown. From Figure 10 As can be seen, the H2 permeation flux (left axis) is as high as approximately 4.5 × 10⁻⁶. -7 mol·m -2 ·s -1 ·Pa -1 The permeation fluxes of NH3 and N2 are extremely low (both less than 5 × 10⁻⁶). -10 mol·m -2 ·s -1 ·Pa -1 Calculations (right axis) show that the membrane has an H2 / NH3 separation factor of 827 and an H2 / N2 separation factor of 893. These results demonstrate that the Pd membrane possesses extremely high hydrogen selective permeability, ensuring in-situ separation of product hydrogen in the subsequent integrated reactor.

[0052] Example 12: Performance Testing of an Integrated System Using a Thicker Pd Film The integrated system constructed in Example 5 (using the 5.2 μm Pd membrane from Example 4 and 0.5 g of ALD-Ru / SiO2 prepared in Example 1) was used for performance testing under the same conditions as in Example 8 (NH3 feed 300 mL / min, reaction temperature 400 °C, combination of plasma catalysis and membrane separation). The test results showed that the NH3 conversion rate of this system was 58.2%. While this conversion rate is still higher than that of the membrane-free system (52.1%), it is lower than that of the system using the 1.8 μm membrane (65.0%). This is because the thicker Pd membrane (5.2 μm) increases hydrogen permeation resistance, reducing the efficiency of in-situ hydrogen separation and thus weakening the synergistic enhancement effect.

[0053] Example 13: Study on the separation performance of S-1 ammonia recovery membrane The separation performance of the S-1 membrane prepared in Example 3 (2) was tested at 25°C and 1 bar for a binary NH3 / H2 mixture. The results are as follows: Figure 11 As shown, when the NH3 concentration in the feed gas increased from 10 mol% to 90 mol%, the NH3 / H2 separation factor continuously increased from approximately 120 to approximately 930. At an NH3 concentration of 70 mol%, the separation factor reached as high as 686, exhibiting extremely high ammonia selectivity, demonstrating its feasibility and superiority for ammonia recovery from tail gas.

[0054] Example 14: Separation performance study of S-1 ammonia recovery membrane under different pressures The effect of transmembrane pressure on the separation performance of NH3 / H2 (70:30 mixture) was investigated on the S-1 membrane prepared in Example 3 (2) at 25°C. The total inlet pressure was increased to 5 bar while maintaining atmospheric pressure on the permeate side. The test results showed that the NH3 / H2 separation factor was 510 under these conditions. Although the separation factor decreased compared to 1 bar (686), it remained at a very high level. This demonstrates that the ammonia recovery membrane of the present invention has good applicability within a certain pressure fluctuation range.

[0055] Example 15: Performance Verification of Downstream Multi-Stage Ammonia Recovery System Using the integrated system constructed in Example 5, the exhaust gas (NH3 concentration 24.05%) from the combination of plasma catalysis and in-situ Pd membrane separation in Example 8 was passed into an ammonia recovery membrane separation system consisting of five S-1 membrane modules connected in series. The recovery process and results are as follows. Figure 12 As shown, the separated NH3 is returned to the recycling system. After five-stage membrane separation, the NH3 concentration in the tail gas successfully decreased from the initial 24.05% to 3.93%, with a cumulative ammonia removal rate exceeding 87.1%. This clearly demonstrates that the multi-stage membrane recovery scheme of this invention can efficiently and with low energy consumption recover unreacted ammonia, achieving closed-loop recycling of raw materials.

Claims

1. A method for enhancing ammonia decomposition and hydrogen production using a plasma-assisted dual-membrane reactor, characterized in that, The process includes the following steps: passing an ammonia-containing feed gas into a plasma catalytic reactor integrated with a hydrogen separation membrane; generating a low-temperature plasma by applying an electric field within the plasma catalytic reactor, and decomposing the ammonia into hydrogen and nitrogen under the action of a catalyst; during the reaction, the generated hydrogen is separated in situ and exported through the hydrogen separation membrane; the catalyst contains at least one metallic active component.

2. The method according to claim 1, characterized in that, It also includes passing tail gas containing unreacted ammonia, nitrogen, and hydrogen into an ammonia recovery membrane separation system to separate and recover the unreacted ammonia.

3. The method according to claim 1 or 2, characterized in that, The plasma is a dielectric barrier discharge plasma; and / or, The plasma catalytic reactor provides a reaction temperature of 100-500 ℃.

4. The method according to claim 1 or 2, characterized in that, The active metal component includes one or more of Ru, Ni, Fe, Co, Pt, and Pd; and / or, The catalyst also includes a support.

5. The method according to claim 4, characterized in that, The active metal component is distributed on the outer surface of the carrier in the form of nanoparticles.

6. The method according to claim 5, characterized in that, The catalyst was prepared by atomic layer deposition (ALD).

7. The method according to claim 1, characterized in that, The hydrogen separation membrane is a hydrogen selective permeation membrane, and the plasma catalytic reactor is a coaxial dielectric barrier discharge reactor. Its dielectric tube is composed of a porous ceramic substrate, and the hydrogen separation membrane is loaded on the inner or outer surface of this porous ceramic substrate. The dielectric tube is filled with a catalyst (7) and equipped with a high-voltage electrode (1) and a grounding electrode (4); and / or, The thickness of the hydrogen separation membrane is ≤2μm.

8. The method according to claim 2, characterized in that, The ammonia recovery membrane separation system employs an ammonia selective permeation membrane; and / or, The ammonia recovered by the ammonia recovery membrane separation system is recycled as raw material gas.

9. The method according to claim 2 or 8, characterized in that, The plasma reactor tail gas outlet is connected to an ammonia recovery membrane separation system, which includes at least two membrane modules connected in series.

10. The method according to claim 7, characterized in that, The plasma catalytic reactor also includes a quartz tube (5) as the outer shell, a porous ceramic substrate being a porous α-Al2O3 tube (6) coaxially disposed inside the quartz tube (5), a high-voltage electrode (1) inserted and fixed in the central channel of the porous α-Al2O3 tube, a grounding electrode (4) wound around the outer wall of the porous α-Al2O3 tube, a hydrogen separation membrane loaded on the inner wall of the porous α-Al2O3 tube, and a catalyst (7) filling the annular region between the high-voltage electrode and the hydrogen separation membrane.

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