Low-temperature and high-efficiency methanol steam reforming reaction process for hydrogen production

Abstract

The present application relates to the hydrogen production from methanol chemical process technical field, specifically disclose a kind of low-temperature efficient methanol steam reforming hydrogen reaction process, the reaction process includes the following steps: S1, raw material preparation: select industrial grade anhydrous methanol and high-purity deionized water as raw material, according to preset water alcohol molar ratio accurate metering ratio, two are input into batching tank constant temperature stirring mixture, stirring speed 300~500r / min, stirring time 5~10min, configuration obtains uniform stable methanol aqueous solution raw material liquid.The present application is additionally added with built-in stirring jacket heat-conducting oil heating horizontal gas mixing preheater, change traditional process only rely on natural heat transfer preheating gaseous raw material mode, by means of built-in stirring structure to gaseous methanol water mixed raw material is forced to disturb, cooperate with jacket heat-conducting oil uniform heating, raw material gas can be whole temperature stably maintained in 185℃-200℃ low-temperature interval, effectively solve the problem of large local temperature difference of raw material gas under low-temperature condition of traditional process.

Description

Technical Field

[0001] This invention relates to the field of methanol-to-hydrogen chemical process technology, and in particular to a low-temperature, high-efficiency methanol steam reforming process for hydrogen production. Background Technology

[0002] Methanol steam reforming for hydrogen production has become the mainstream hydrogen production technology for small and medium-sized hydrogen-using scenarios due to its convenient raw material storage and transportation, mild reaction conditions, and low hydrogen production cost. However, conventional methanol steam reforming hydrogen production processes in the industry generally suffer from core problems such as uneven heating of the raw material gas in the low-temperature range, poor reaction stability, high carbon monoxide production as a byproduct, and high hydrogen purification load.

[0003] Existing processes often employ conventional tubular heat exchangers for centralized preheating of vaporized methanol-water vapor. The gaseous material relies solely on natural convection for heat transfer within the pipelines and heat exchange equipment, lacking any forced disturbance. When the process is controlled within a low-temperature reaction range of 185℃-200℃, localized temperature deviations easily occur in the gaseous methanol-water mixture. Temperatures in some areas fall below the set reaction values, leading not only to a decrease in methanol reforming conversion rate but also to unreacted methanol entering subsequent purification units, significantly increasing the processing pressure on condensation and adsorption processes. Furthermore, uneven temperature distribution results in significant differences in catalytic reaction rates within the fixed-bed reactor, leading to an imbalance in the reaction load distribution on the catalyst surface. Excessive localized reactions can exacerbate side reactions, increasing the carbon monoxide content in the reformed gas mixture. Carbon monoxide is a toxic impurity that directly affects the quality of subsequent high-purity hydrogen products and shortens the lifespan of the composite adsorbent in the pressure swing adsorption system. Therefore, to address these issues, a low-temperature, high-efficiency methanol-water vapor reforming process for hydrogen production is proposed. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low-temperature, high-efficiency methanol steam reforming process for hydrogen production.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A low-temperature, high-efficiency methanol steam reforming process for hydrogen production includes the following steps:

[0007] S1. Raw material preparation: Select industrial-grade anhydrous methanol and high-purity deionized water as raw materials, and accurately measure and mix them according to the preset water-methanol molar ratio. Put the two into the mixing tank and stir at a constant temperature. The stirring speed is 300-500 r / min and the stirring time is 5-10 min to prepare a uniform and stable methanol-water solution.

[0008] S2. Raw material preheating and vaporization: The prepared methanol-water solution is quantitatively delivered to the preheating and vaporization unit through a metering pump. The raw material is preheated and vaporized at a constant temperature in stages to remove trace dissolved impurities in the raw material and obtain a gaseous methanol-water mixture with a dryness of ≥99.5%.

[0009] S3. Preheating and Insulation of Gaseous Methanol-Water Mixture: Construct a horizontal gas mixing preheater with a built-in stirrer and heat transfer oil heating. Introduce the gaseous methanol-water mixture obtained in S2 into the horizontal gas mixing preheater with a built-in stirrer and heat transfer oil heating. Start the horizontal gas mixing preheater with a built-in stirrer and heat the gaseous methanol-water mixture in the preheater to 185℃-200℃. Stir the gaseous methanol-water mixture in the preheater to ensure uniform heating and temperature uniformity, keeping the temperature of the gaseous methanol-water mixture between 185℃ and 200℃.

[0010] S4. Catalyst pretreatment: The modified copper-based composite catalyst packed in the fixed-bed reformer is purged and reduced in situ to remove air, moisture and impurities adsorbed on the catalyst surface, so as to fully activate the active sites of the catalyst.

[0011] S5. Low-temperature reforming hydrogen production reaction: After activation, the reactor is heated to the reaction temperature. A gaseous methanol-water mixture with a temperature maintained at 185℃-200℃ is uniformly fed into the fixed-bed reforming reactor. The temperature, pressure and material space velocity in the reactor are controlled to produce a low-temperature methanol-water vapor reforming reaction, continuously generating a reformed mixture containing hydrogen, carbon dioxide and trace amounts of carbon monoxide.

[0012] S6. Mixed gas pressure stabilization and buffer: The reformed mixed gas discharged from the reactor is introduced into the buffer pressure stabilization tank to stabilize the mixed gas pressure and flow rate, eliminate the gas flow pulsation caused by reaction fluctuations, and ensure the stability of the subsequent purification process.

[0013] S7. Mixed gas condensation and impurity removal: The regulated reformed mixed gas is sent to the condensation unit for low-temperature condensation to remove unreacted liquid methanol, free water and heavy component impurities from the mixed gas, and obtain a preliminarily purified dry mixed gas.

[0014] S8. High-precision adsorption purification: The pre-purified dry mixed gas is sent into the pressure swing adsorption purification system. Through the selective adsorption of carbon oxides and residual methanol impurities by the composite adsorbent, high-purity hydrogen products with qualified purity and extremely low impurity content are obtained.

[0015] Preferably, in step S1, the water-ethanol molar ratio of industrial-grade anhydrous methanol to high-purity deionized water is controlled at 1.1-1.8:1, and the constant temperature mixing temperature in the mixing tank is set to 40℃-60℃.

[0016] Preferably, in S2, the preheating vaporization unit adopts a multi-stage tube vaporizer, with the preheating temperatures of 70℃, 110℃, and 140℃ respectively, and the constant temperature vaporization temperature controlled at 150℃-170℃.

[0017] Preferably, in step S3, the internal stirring paddle speed of the jacketed heat transfer oil heated horizontal gas mixing preheater is 80-150 r / min, and the circulating temperature of the heat transfer oil inside the jacket is maintained at 190℃-205℃.

[0018] Preferably, in step S4, the catalyst is purged in situ using room temperature nitrogen as the purging medium for 2-4 hours; the reduction activation uses a mixture of hydrogen and nitrogen as the reducing gas, with a reduction temperature of 170℃-180℃ and an activation time of 6-8 hours.

[0019] Preferably, in step S5, the internal reaction pressure of the fixed-bed reforming reactor is controlled at 0.15-0.35 MPa.

[0020] Preferably, in step S6, the buffer pressure stabilizing tank is equipped with multiple porous rectifier plates, and the pressure difference between the stabilizing pressure inside the tank and the outlet pressure of the fixed bed reforming reactor is controlled within ±0.02MPa.

[0021] Preferably, in step S7, the condensation unit adopts a shell-and-tube type low-temperature condenser, the condensation temperature is controlled at 5℃-15℃, and the liquid impurities generated during condensation are uniformly returned to the mixing tank for recycling.

[0022] Preferably, in step S8, the pressure swing adsorption purification system uses a composite adsorbent composed of activated carbon, molecular sieve, and activated alumina, and the adsorption working pressure is 0.2-0.4 MPa.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. This invention adds a jacketed thermal oil-heated horizontal gas mixing preheater with built-in stirring, changing the traditional process that relies solely on natural heat exchange to preheat gaseous raw materials. By using a built-in stirring structure to forcibly disturb the gaseous methanol-water mixture, combined with uniform heating from the jacketed thermal oil, the overall temperature of the raw material gas can be stably maintained in the low-temperature range of 185℃-200℃. This effectively solves the problem of large local temperature differences in the raw material gas under low-temperature conditions in traditional processes. After the raw material gas temperature is uniform, the reaction starting point is consistent when it enters the fixed-bed reactor, significantly improving the conversion rate of methanol reforming reaction. This greatly reduces the flow of unreacted methanol with the mixed gas to subsequent processes, reducing the impurity treatment load of the condensation unit and pressure swing adsorption unit from the source, reducing the wear and tear on adsorbent and condensation equipment, and avoiding the problem of reaction stagnation and reduced production capacity due to low raw material gas temperature. This allows for the stable implementation of low-temperature hydrogen production.

[0025] 2. This invention systematically limits and optimizes the parameters of each step in the entire process, forming a complete matching system from raw material ratio, vaporization classification, catalyst activation to reaction parameters and post-treatment conditions. The modified copper-based composite catalyst undergoes in-situ purging and gradient reduction activation, thoroughly removing surface-adsorbed impurities and air, fully activating active sites, and maintaining high catalytic activity even at low temperatures of 185℃-200℃. The uniform feed gas combined with the highly active catalyst effectively suppresses side reactions during reforming, significantly reducing the generation of toxic byproducts such as carbon monoxide in the mixed gas. This improves the purity of the final hydrogen product, reduces the toxic effects of carbon monoxide on the adsorbent, extends the replacement cycle of the composite adsorbent in the pressure swing adsorption system, and lowers equipment maintenance and consumable procurement costs.

[0026] 3. In this invention, a buffer pressure stabilizing tank is installed at the rear end of the reforming reactor, along with a multi-layer porous rectifier plate structure. This can quickly absorb the gas flow pulsations of the mixed gas discharged from the reactor, stabilizing the pressure and flow rate of the entire system. Traditional processes lack a pressure stabilizing and buffering stage, and reaction fluctuations within the reactor are directly transmitted to the condensation and adsorption processes, easily causing malfunctions in the operating conditions of subsequent equipment and sudden changes in operating load.

[0027] 4. The overall process in this invention relies on low-temperature reaction conditions, which significantly reduces the energy consumption of the heating system compared to the traditional high-temperature methanol reforming hydrogen production process. Under the premise of ensuring high hydrogen production efficiency and high product purity, it achieves a triple reduction in energy consumption, raw material loss and operation and maintenance costs, resulting in a significant improvement in overall economic benefits. Attached Figure Description

[0028] Figure 1 This is a flowchart of a low-temperature, high-efficiency methanol steam reforming process for hydrogen production proposed in this invention. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0030] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] Reference Figure 1 A low-temperature, high-efficiency methanol steam reforming process for hydrogen production begins with the S1 feedstock preparation step. The feedstock used in this step is commercially available industrial-grade anhydrous methanol with a purity of not less than 99.5%. The accompanying feedstock is electronic-grade high-purity deionized water with a conductivity ≤1μS / cm, preventing impurities from contaminating subsequent catalysts and adsorbents. The water-to-methanol molar ratio is 1.1-1.8:1, with a preferred ratio of 1.5:1 in this embodiment. This ratio balances methanol reforming conversion rate and feedstock utilization, representing the optimal range under low-temperature conditions. The batching equipment is a vertical sealed batching tank equipped with a jacketed water circulation thermostatic structure, a top-mounted mechanical stirrer, and a precise metering inlet. Before operation, the inside of the batching tank is cleaned and dried to ensure no residual impurities or accumulated water remain. First, a measured amount of industrial-grade anhydrous methanol is added to the mixing tank using a metering device. Then, high-purity deionized water of the corresponding ratio is slowly added. The stirring device is started, and the stirring speed is set to 300-500 r / min (400 r / min is used in this embodiment). The stirring time is controlled to 5-10 minutes (8 minutes in this embodiment). Simultaneously, the mixing tank jacket temperature control system is activated to stabilize the mixing temperature in the tank at 50°C. The purpose of constant temperature stirring is to ensure that methanol and deionized water are fully miscible, avoiding localized uneven concentrations, and ultimately preparing a methanol-water solution with uniform composition and stable properties. After the raw material preparation is completed, the mixing tank is kept under slight positive pressure and sealed to prevent methanol evaporation, which could lead to raw material loss and safety hazards.

[0032] Next, the S2 raw material preheating and vaporization process is carried out. The prepared methanol-water solution is transported to a high-precision metering pump by the pressure of the mixing tank itself. The metering pump is a variable frequency positive displacement pump, which can accurately control the flow rate of the raw material and ensure a constant material delivery rate for the entire process. The raw material is quantitatively fed into the preheating and vaporization unit by the metering pump. This unit is equipped with a multi-stage tube vaporizer, consisting of three stages of progressive preheating and one stage of constant-temperature vaporization. The first-stage tube preheater heats the liquid to 70°C, mainly to initially raise the temperature of the room-temperature raw material and reduce the subsequent vaporization load. The second-stage preheater heats the liquid to 110°C to further increase the liquid temperature. The third-stage preheater heats the liquid to 140°C, bringing the raw material close to the saturation vaporization temperature. After three stages of progressive preheating, the liquid raw material enters the constant-temperature vaporizer, where the internal temperature is stably controlled at 160°C. This temperature is lower than the high-temperature range of methanol decomposition and ensures that the methanol-water solution is fully vaporized. The feed liquid undergoes a phase change within the vaporization unit. Trace amounts of dissolved air and suspended solid impurities in the feed liquid are carried away and separated by the airflow, ultimately producing a gaseous methanol-water mixture with a dryness of ≥99.5%. This process employs a step-by-step heating vaporization mode to avoid problems such as explosive boiling and gas-liquid entrainment caused by instantaneous high-temperature vaporization of the feed liquid, ensuring the stability of the gaseous feed component and laying the foundation for the subsequent homogenization and preheating process.

[0033] Next, the S3 gaseous methanol-water mixture raw material preheating and insulation process is performed. This process is the core improvement of this invention, abandoning the traditional single-tube heat exchanger and selecting a jacketed heat transfer oil heating horizontal gas mixing preheater with built-in stirring. This equipment has a horizontal cylindrical structure with a sealed heat transfer oil jacket on the outside of the cylinder. A continuous spiral stirring paddle is installed axially inside the cylinder. The raw material inlet and outlet are respectively set at both ends of the equipment, and it is equipped with an independent heat transfer oil circulation heating system and stirring drive motor. The gaseous methanol-water mixture raw material produced in S2 is introduced into the equipment through the inlet, and the heat transfer oil circulation system is started. The heat transfer oil circulation temperature in the jacket is controlled at 190℃-205℃, and in this embodiment, it is set to 198℃. The heat transfer oil uniformly heats the gaseous material inside the cylinder. At the same time, the built-in stirring device is started, and the stirring paddle speed is set to 80-150 r / min, and in this embodiment, 120 r / min is selected. The stirring paddle continuously forces and mixes the gaseous material inside, completely breaking the temperature stratification phenomenon formed by natural convection of the gaseous material. The overall temperature control system of the equipment precisely heats and maintains the internal gaseous raw materials at a constant temperature of 185℃-200℃, and in this embodiment, it is stably controlled at 192℃. The residence time of the gaseous raw materials inside the equipment is controlled within 15-25 seconds, ensuring that the temperature of all materials is completely uniform, without any localized high or low temperature areas. The gaseous raw materials processed in this step have a uniform temperature and stable composition, fundamentally solving the defect of large temperature differences in raw material temperatures in traditional low-temperature hydrogen production processes, and providing qualified feedstock for subsequent low-temperature reforming reactions.

[0034] Then, the S4 catalyst pretreatment process is carried out. Before the entire unit is put into operation, the modified copper-based composite catalyst packed inside the fixed-bed reforming reactor needs to undergo in-situ purging and reduction activation treatment. The fixed-bed reforming reactor is a vertical cylindrical structure, with the catalyst layered and packed in the reactor bed. Porous support plates and packing layers are set above and below the bed to prevent catalyst particles from being carried away by the airflow. First, high-purity nitrogen at room temperature is used as the purging medium, with a nitrogen purity ≥99.99%. The nitrogen is introduced from the bottom of the reactor and passes through the catalyst bed from top to bottom. The purging time is set to 2-4 hours, and in this embodiment, it is 3 hours. Through nitrogen purging, all air, free moisture, and dust impurities adsorbed on the catalyst surface and in the interparticle gaps are removed from the reactor, avoiding impurities from affecting the catalyst activity. After purging, the process is switched to a hydrogen-nitrogen mixed reducing gas, with hydrogen accounting for 8%-12% of the gas volume (10% in this embodiment). The reactor internal temperature is gradually increased to 170℃-180℃ (175℃ in this embodiment), and isothermal reduction activation is performed for 6-8 hours (7 hours in this embodiment). After reduction activation, the metal oxides on the surface of the modified copper-based composite catalyst are reduced to active metal components, and the active sites inside the catalyst are fully activated, enabling low-temperature catalytic reforming reactions. A slight positive pressure is maintained inside the reactor after pretreatment to prevent outside air from re-entering.

[0035] After catalyst pretreatment, the reactor proceeds to the S5 low-temperature reforming hydrogen production process. The overall temperature of the fixed-bed reforming reactor is slowly increased to maintain a stable temperature of 192°C, consistent with the temperature of the gaseous feedstock at the front end. The gaseous methanol-water mixture, treated in S3 and kept at a constant temperature, is uniformly fed into the bottom of the reactor. The material passes through the catalyst bed from bottom to top, undergoing the main methanol-water vapor reforming reaction. Simultaneously, reactor operating parameters are strictly controlled: according to claim 6, the internal reaction pressure is controlled between 0.15-0.35 MPa; in this embodiment, 0.25 MPa is used. Under the catalytic action of the modified copper-based composite catalyst, methanol and water vapor undergo a reforming reaction, with hydrogen and carbon dioxide as the main products and only trace amounts of carbon monoxide as a byproduct. Due to the uniform temperature of the gaseous feedstock at the front end, sufficient catalyst activity, and consistent reaction rates throughout the reactor, there is no localized overheating or reaction imbalance in the bed, resulting in a methanol conversion rate of over 96%. The reformed gas mixture generated after the reaction is discharged from the top outlet of the reactor. The main components of the mixture are hydrogen and carbon dioxide, with trace amounts of carbon monoxide, unreacted methanol vapor and water vapor. The entire reaction process operates in a low temperature range of 185℃-200℃, eliminating the need for the high-temperature heating system of traditional processes and significantly reducing energy consumption.

[0036] After the reformed gas mixture exits the reactor, it enters the S6 gas mixture stabilization and buffering process. The reactor outlet pipeline is directly connected to the buffer pressure stabilizing tank. This tank is a vertical pressure-bearing tank with three layers of staggered perforated flow straighteners inside. The flow straighteners have a hole diameter of 3-5mm, which can divert and rectify the high-speed gas flow. After the reformed gas mixture enters the tank, the gas flow pulsation is fully absorbed by the tank cavity and the flow straighteners. The pressure inside the tank is monitored in real time and automatically adjusted to ensure that the pressure difference between the tank and the reactor outlet pressure is controlled within ±0.02MPa. In traditional processes, even small fluctuations in the reactor reaction load can cause drastic changes in gas flow pressure and velocity, directly impacting subsequent condensation and adsorption equipment. This buffer pressure stabilizing tank acts as an isolation mechanism, keeping the pressure and velocity of the gas mixture exiting the tank constant, completely eliminating the negative impact of reaction fluctuations. The gas mixture stays in the buffer pressure stabilizing tank for about 20 seconds. After pressure stabilization, it is smoothly conveyed to the next process from the side outlet of the tank.

[0037] After pressure stabilization, the mixed gas enters the S7 mixed gas condensation and impurity removal process. This process uses a shell-and-tube cryogenic condenser, with the reformed mixed gas flowing through the tubes and cryogenic circulating cooling water flowing through the shell. The condensation temperature is controlled between 5℃ and 15℃; in this embodiment, it is set to 10℃. Under cryogenic conditions, unreacted methanol vapor, free water vapor, and a small amount of heavy component impurities in the mixed gas undergo rapid phase change and condense into liquid, accumulating in the liquid collection chamber at the bottom of the condenser. Gaseous non-condensable gases such as hydrogen, carbon dioxide, and carbon monoxide are discharged from the top of the condenser, becoming a preliminarily purified dry mixed gas. An automatic drain valve is installed at the bottom of the condenser, and the liquid methanol and mixed water produced during condensation are periodically discharged and transported through a return pipeline to the upstream S1 batching tank for recycling and reuse, achieving raw material recycling and reducing waste. This process can remove more than 98% of liquid impurities from the mixed gas, significantly reducing the processing load of the subsequent pressure swing adsorption system. Simultaneously, cryogenic condensation does not cause hydrogen loss, ensuring hydrogen production yield.

[0038] Finally, the S8 high-precision adsorption purification process is performed. The dry mixed gas, after condensation and impurity removal, is fed into a pressure swing adsorption (PSA) purification system. This system is a multi-tower continuous PSA device, filled with a composite adsorbent prepared according to claim 9, which is composed of activated carbon, molecular sieves, and activated alumina in a specific ratio. The system's adsorption working pressure is set at 0.3 MPa. Under this pressure condition, the composite adsorbent selectively adsorbs carbon dioxide, carbon monoxide, and trace amounts of residual methanol impurities in the mixed gas, while hydrogen is not adsorbed and passes directly through the adsorption bed, exiting from the top of the adsorption tower. After adsorption saturation, the adsorption towers are regenerated through depressurization, rinsing, and pressurization. Multiple towers work alternately to achieve continuous purification operations.

[0039] Throughout the continuous operation of the entire process, all connecting pipelines between processes utilize seamless industrial steel pipes. The outer walls of the pipelines are entirely covered with a 30mm thick aluminum silicate insulation layer. Temperature drop in the pipelines is controlled according to claim 10, ensuring a temperature drop of ≤3℃ per 10 meters. This effectively prevents condensation of gaseous raw materials and mixed gases during transport, further ensuring stable operation throughout the entire process. From raw material addition to finished hydrogen production, the parameters of each process are matched, and the equipment functions complement each other. Based on the design concepts of low-temperature reaction, uniform preheating of raw materials, multi-stage purification, and recycling, the process achieves low-temperature, high-efficiency, low-energy-consumption, and low-cost methanol steam reforming for hydrogen production.

[0040] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A low-temperature, high-efficiency methanol steam reforming process for hydrogen production, characterized in that, The reaction process includes the following steps: S1. Raw material preparation: Select industrial-grade anhydrous methanol and high-purity deionized water as raw materials, and accurately measure and mix them according to the preset water-methanol molar ratio. Put the two into the mixing tank and stir at a constant temperature. The stirring speed is 300-500 r / min and the stirring time is 5-10 min to prepare a uniform and stable methanol-water solution. S2. Raw material preheating and vaporization: The prepared methanol-water solution is quantitatively delivered to the preheating and vaporization unit through a metering pump. The raw material is preheated and vaporized at a constant temperature in stages to remove trace dissolved impurities in the raw material and obtain a gaseous methanol-water mixture with a dryness of ≥99.5%. S3. Preheating and Insulation of Gaseous Methanol-Water Mixture: Construct a horizontal gas mixing preheater with a built-in stirrer and heat transfer oil heating. Introduce the gaseous methanol-water mixture obtained in S2 into the horizontal gas mixing preheater with a built-in stirrer and heat transfer oil heating. Start the horizontal gas mixing preheater with a built-in stirrer and heat the gaseous methanol-water mixture in the preheater to 185℃-200℃. Stir the gaseous methanol-water mixture in the preheater to ensure uniform heating and temperature uniformity, keeping the temperature of the gaseous methanol-water mixture between 185℃ and 200℃. S4. Catalyst pretreatment: The modified copper-based composite catalyst packed in the fixed-bed reformer is purged and reduced in situ to remove air, moisture and impurities adsorbed on the catalyst surface, so as to fully activate the active sites of the catalyst. S5. Low-temperature reforming hydrogen production reaction: After activation, the reactor is heated to the reaction temperature. A gaseous methanol-water mixture with a temperature maintained at 185℃-200℃ is uniformly fed into the fixed-bed reforming reactor. The temperature, pressure and material space velocity in the reactor are controlled to produce a low-temperature methanol-water vapor reforming reaction, continuously generating a reformed mixture containing hydrogen, carbon dioxide and trace amounts of carbon monoxide. S6. Mixed gas pressure stabilization and buffer: The reformed mixed gas discharged from the reactor is introduced into the buffer pressure stabilization tank to stabilize the mixed gas pressure and flow rate, eliminate the gas flow pulsation caused by reaction fluctuations, and ensure the stability of the subsequent purification process. S7. Mixed gas condensation and impurity removal: The regulated reformed mixed gas is sent to the condensation unit for low-temperature condensation to remove unreacted liquid methanol, free water and heavy component impurities from the mixed gas, and obtain a preliminarily purified dry mixed gas. S8. High-precision adsorption purification: The pre-purified dry mixed gas is sent into the pressure swing adsorption purification system. Through the selective adsorption of carbon oxides and residual methanol impurities by the composite adsorbent, high-purity hydrogen products with qualified purity and extremely low impurity content are obtained.

2. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In step S1, the water-ethanol molar ratio of industrial-grade anhydrous methanol to high-purity deionized water is controlled at 1.1-1.8:1, and the constant temperature mixing temperature in the mixing tank is set to 40℃-60℃.

3. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In S2, the preheating vaporization unit adopts a multi-stage tube vaporizer, with the preheating temperatures of 70℃, 110℃, and 140℃ respectively, and the constant temperature vaporization temperature is controlled between 150℃ and 170℃.

4. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In S3, the speed of the built-in agitator in the jacketed heat transfer oil heating horizontal gas mixing preheater is 80-150 r / min, and the temperature of the heat transfer oil circulation inside the jacket is maintained at 190℃-205℃.

5. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In S4, the catalyst is purged in situ using room temperature nitrogen as the purging medium for 2-4 hours; the reduction activation uses a mixture of hydrogen and nitrogen as the reducing gas, with a reduction temperature of 170℃-180℃ and an activation time of 6-8 hours.

6. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In S5, the internal reaction pressure of the fixed-bed reforming reactor is controlled at 0.15-0.35 MPa.

7. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In S6, the buffer pressure stabilizing tank is equipped with multiple porous rectifier plates, and the pressure difference between the stabilizing pressure inside the tank and the outlet pressure of the fixed bed reforming reactor is controlled within ±0.02MPa.

8. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In S7, the condensation unit adopts a shell-and-tube type low-temperature condenser, and the condensation temperature is controlled at 5℃-15℃. The liquid impurities generated during condensation are uniformly returned to the batching tank for recycling.

9. The low-temperature, high-efficiency methanol steam reforming process for hydrogen production according to claim 1, characterized in that, In S8, the pressure swing adsorption purification system uses a composite adsorbent composed of activated carbon, molecular sieve, and activated alumina, with an adsorption working pressure of 0.2-0.4 MPa.

Images