Method for hydrothermally preparing hydrogen from household garbage and application of method

Abstract

The invention provides a method for hydrothermally preparing hydrogen from household garbage and application of the method, and relates to the technical field of solid waste resource.The method comprises the following steps that pretreated household garbage is subjected to a hydrothermal reaction under catalysis of Fe2O3-CuO / Al2O3, a product is separated, and hydrogen is obtained; wherein the dosage of Fe2O3-CuO / Al2O3 accounts for 0.5%-2% of the mass of the household garbage; the hydrothermal reaction comprises a stepped heating stage, a dynamic constant-temperature reaction stage and a gradient cooling stage. Organic components in the household garbage can be fully utilized and converted into hydrogen through the hydrothermal reaction, reduction, harmlessness and resourceful treatment of the household garbage are achieved, and the technical effects of improving the hydrogen yield and purity, reducing the production cost and enhancing the industrial feasibility of the process are achieved.

Description

Technical Field

[0001] This invention relates to the technical field of solid waste resource utilization, and in particular to a method for hydrothermal hydrogen production from municipal solid waste and its application. Background Technology

[0002] With rapid global economic development and continuous population growth, the amount of municipal solid waste generated is increasing daily. Traditional methods of municipal solid waste disposal, such as landfill and incineration, not only occupy a large amount of land resources but also cause secondary pollution to the environment. For example, leachate from landfills pollutes soil and groundwater, while incineration releases harmful gases such as dioxins and sulfides into the atmosphere. At the same time, the energy crisis and environmental pollution problems are becoming increasingly serious, making the search for clean and renewable energy a top priority.

[0003] Hydrogen, as a highly efficient and clean energy carrier, produces only water as a combustion byproduct, causing no environmental pollution. Furthermore, it boasts high energy density and is considered a crucial direction for future energy development. However, current hydrogen production methods, such as fossil fuel reforming and water electrolysis, suffer from high costs, reliance on non-renewable resources, and high energy consumption. Therefore, developing a technology that can effectively treat municipal solid waste while producing hydrogen at low cost is of significant practical importance.

[0004] While existing technologies have attempted to produce hydrogen using biomass hydrothermal processes, they suffer from problems such as incomplete pretreatment leading to low reaction efficiency, poor catalyst selectivity resulting in low hydrogen yield, and cumbersome product separation and purification processes when dealing with complex municipal solid waste.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for hydrothermal preparation of hydrogen from municipal solid waste, which can fully utilize the organic components in municipal solid waste and convert them into hydrogen through a hydrothermal reaction, thereby achieving the reduction, harmlessness and resource utilization of municipal solid waste. This method also achieves the technical effects of improving hydrogen yield and purity, reducing production costs and enhancing the industrial feasibility of the process.

[0007] The second objective of this invention is to provide an application of a method for hydrothermal hydrogen production from municipal solid waste, which is beneficial for the resource utilization of solid waste.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, a method for hydrothermal preparation of hydrogen from municipal solid waste includes the following steps: Pretreated municipal solid waste was subjected to a hydrothermal reaction under the catalysis of Fe2O3-CuO / Al2O3, and the products were separated to obtain hydrogen gas. The amount of Fe2O3-CuO / Al2O3 used accounts for 0.5%-2% of the mass of municipal solid waste; The hydrothermal reaction includes a stepped heating stage, a dynamic isothermal reaction stage, and a gradient cooling stage. The stepped heating stage includes first heating from room temperature to 140℃-160℃ at a rate of 4℃ / min-6℃ / min, and then heating from 140℃-160℃ to 250℃-350℃ at a rate of 8℃ / min-10℃ / min. The dynamic isothermal reaction stage includes real-time monitoring of the hydrogen concentration in the gaseous products. When the hydrogen concentration is below 15%, the rotation speed is increased by 20-30 r / min and 0.1%-0.2% catalyst is added. The gradient cooling stage includes first cooling from the reaction temperature to 190℃-210℃ at a rate of 7℃ / min-9℃ / min, and then cooling from 190℃-210℃ to room temperature at a rate of 11℃ / min-13℃ / min.

[0009] Furthermore, the preprocessing includes the following steps: First, the household waste is screened to obtain organic waste. Then, the organic waste is crushed to obtain crushed organic waste. Finally, the crushed organic waste is desalinated to obtain pre-treated household waste.

[0010] Furthermore, the screening includes manual preliminary screening and intelligent fine screening; Preferably, the manual preliminary screening includes screening and separating construction waste and hazardous waste; Preferably, the intelligent fine screening includes automated sorting of waste through near-infrared spectroscopy recognition equipment and AI image recognition system, screening and separating metal, glass and plastic; Preferably, the organic waste includes at least one of kitchen waste, paper, and wood.

[0011] Furthermore, the crushing includes a graded crushing process; Preferably, the graded crushing process includes the following steps: Under the protection of inert gas, the organic waste is first coarsely crushed to a particle size of 20mm-30mm, and then finely crushed to a particle size of 2mm-5mm.

[0012] Furthermore, the desalination process includes the following steps: The crushed organic waste is desalinated using a combination of water washing and ultrasonic assistance. Preferably, the mass ratio of the crushed organic waste to water is 1:3 to 1:5; Preferably, the power of the ultrasonic wave is 300W-500W and the frequency is 20kHz-40kHz; Preferably, the desalination rate of the desalination treatment is above 90%.

[0013] Furthermore, the specific surface area of ​​the Fe2O3-CuO / Al2O3 is ≥150m². 2 / g, with an average particle size of 20nm-30nm; Preferably, the pore size distribution of the Fe2O3-CuO / Al2O3 is concentrated between 2nm and 5nm.

[0014] Furthermore, the Fe2O3-CuO / Al2O3 is reduced and activated in a hydrogen atmosphere before use; Preferably, the flow rate of the hydrogen gas used for reduction and activation is 50 mL / min to 100 mL / min; Preferably, the reduction and activation temperature is 300℃-400℃, and the time is 2h-3h.

[0015] Furthermore, the separation process sequentially includes gas-liquid separation, gas purification, and hydrogen purification; Preferably, the gas-liquid separation includes three-stage gas-liquid separation; Preferably, the three-stage gas-liquid separation includes gravity sedimentation separation, cyclone separation, and membrane separation in sequence; Preferably, the residence time for gravity settling separation is at least 10 minutes; Preferably, the separation efficiency of the cyclone separator is ≥98%; Preferably, the separation efficiency of the membrane separation is ≥99.5%; Preferably, the gas purification includes water washing purification and alkaline washing purification; Preferably, the hydrogen purification includes hydrogen purification using a pressure swing adsorption device.

[0016] Furthermore, the pressure swing adsorption device adopts a 4-6 tower process; Preferably, the adsorbent used in the pressure swing adsorption device includes a metal-organic framework material; Preferably, the metal-organic framework material includes HKUST-1; Preferably, the pressure of the pressure swing adsorption device is 0.8MPa-1.2MPa, and the adsorption time is 3min-5min.

[0017] Secondly, the application of any of the above-mentioned methods for hydrothermal hydrogen production from municipal solid waste in the resource utilization of solid waste.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention provides a method for hydrothermal hydrogen production from municipal solid waste, which can fully utilize the organic components in municipal solid waste to convert them into hydrogen through a hydrothermal reaction, thereby achieving the reduction, harmlessness, and resource utilization of municipal solid waste. It also provides a new and sustainable approach to hydrogen production. The invention employs a highly efficient composite catalyst, Fe2O3-CuO / Al2O3, to pretreat the municipal solid waste. Furthermore, it utilizes an innovative reaction control mechanism—a stepped heating and dynamic isothermal reaction mechanism combined with gradient cooling and heat recovery technology—which not only improves reaction efficiency but also reduces energy consumption. The energy consumption per unit of hydrogen produced is reduced by 15%-20% compared to existing technologies. In summary, through the synergistic cooperation of each step and its process parameters, the present invention not only effectively improves hydrogen yield and purity and reduces production costs but also enhances the industrial feasibility of the process.

[0019] The application of the hydrothermal hydrogen production method for municipal solid waste provided by this invention is beneficial for the resource utilization of solid waste. Detailed Implementation The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] According to a first aspect of the present invention, a method for hydrothermal preparation of hydrogen from municipal solid waste is provided, comprising the following steps: Pretreated municipal solid waste was subjected to a hydrothermal reaction under the catalysis of Fe2O3-CuO / Al2O3, and the products were separated to obtain hydrogen. The amount of Fe2O3-CuO / Al2O3 used can account for 0.5%-2% of the mass of municipal solid waste, for example, 0.5%, 1%, 1.5%, 2%, but is not limited to this. Hydrothermal reactions include, but are not limited to, a stepped heating stage, a dynamic isothermal reaction stage, and a gradient cooling stage. The stepped heating stage includes, but is not limited to, first heating from room temperature to 140℃-160℃ at a rate of 4℃ / min-6℃ / min, and then heating from 140℃-160℃ to 250℃-350℃ at a rate of 8℃ / min-10℃ / min. The dynamic isothermal reaction stage includes, but is not limited to, real-time monitoring of the hydrogen concentration in the gaseous products. When the hydrogen concentration is below 15%, the rotation speed is increased by 20-30 r / min and 0.1%-0.2% catalyst is added. The gradient cooling stage includes, but is not limited to, first cooling from the reaction temperature to 190℃-210℃ at a rate of 7℃ / min-9℃ / min, and then cooling from 190℃-210℃ to room temperature at a rate of 11℃ / min-13℃ / min.

[0021] It should be noted that the hydrothermal reaction can use a 316L stainless steel reactor that is resistant to high temperatures (≥500℃) and high pressures (≥20MPa). The inner wall of the reactor can be coated with a 0.5mm-1mm thick titanium alloy coating (Ti-6Al-4V), which is beneficial to improve corrosion resistance and wear resistance. The volume of the reactor is determined according to the actual production scale, generally ranging from 50L to 500L. It can be equipped with a high-precision temperature control system (temperature control accuracy ±1℃), a pressure control system (pressure control accuracy ±0.05MPa), a double-layer stirring device (inner anchor-type stirring paddle + outer propeller-type stirring paddle), as well as an online gas sampling port and a liquid circulation outlet.

[0022] During the stepped heating stage, the inlet and outlet valves of the reactor are closed, and the double-layer stirring device is started. The inner anchor-type stirring paddle rotates at 80 r / min-120 r / min, and the outer propeller-type stirring paddle rotates at 150 r / min-250 r / min. The reactor's electric heating system is used for stepped heating. Specifically, in the first stage, the temperature is increased from room temperature to 150°C at a rate of 5°C / min, and in the second stage, the temperature is increased from 150°C to 250°C-350°C at a rate of 8°C / min-10°C / min. During the heating process, the pressure can be controlled in real time through the online pressure monitoring system, and the pressure inside the reactor increases synchronously with the temperature to 8MPa-15MPa.

[0023] Once the temperature inside the reactor reaches the set temperature, it enters the dynamic isothermal reaction stage. The reaction time is determined based on the composition of the waste and the reaction temperature, ranging from 1 to 3 hours. During this stage, the concentration of hydrogen in the gaseous products is monitored in real time by an automatic control system. When the hydrogen concentration is below 15%, the stirring speed is automatically increased (by 20 to 30 rpm) and 0.1% to 0.2% catalyst is added. When the pressure exceeds the set value of 1.5 MPa, a small amount of gas is released through a fine-tuning exhaust valve to maintain pressure stability. Under the action of high temperature, high pressure, and composite catalyst, the organic matter in the municipal solid waste undergoes a series of complex chemical reactions, including decomposition, hydrolysis, and reforming, generating gases such as hydrogen, carbon dioxide, carbon monoxide, and methane, as well as small amounts of liquid products such as organic acids and alcohols.

[0024] After the reaction is completed, heating is stopped, and the jacketed water cooling system of the reactor is started to enter the gradient cooling stage. In the first stage, the temperature is reduced from the reaction temperature to 200℃ at a rate of 7℃ / min-9℃ / min. In the second stage, the temperature is reduced from 200℃ to room temperature at a rate of 11℃ / min-13℃ / min. During the cooling process, the heat is recovered to preheat the subsequent batches of deionized water, and the heat recovery rate is ≥40%.

[0025] In summary, this invention fully utilizes the organic components in municipal solid waste to convert them into hydrogen through a hydrothermal reaction, achieving the reduction, harmlessness, and resource recovery of municipal solid waste. It also provides a new and sustainable approach to hydrogen production. This invention employs a highly efficient composite catalyst, Fe2O3-CuO / Al2O3, to pretreat municipal solid waste. Furthermore, it utilizes an innovative reaction control mechanism—a stepped heating and dynamic isothermal reaction mechanism combined with gradient cooling and heat recovery technology—which not only improves reaction efficiency but also reduces energy consumption. The energy consumption per unit of hydrogen is reduced by 15%-20% compared to existing technologies. In conclusion, through the synergistic cooperation of each step and its process parameters, this invention not only effectively improves hydrogen yield and purity and reduces production costs but also enhances the industrial feasibility of the process.

[0026] In a preferred embodiment, the preprocessing includes the following steps: First, the household waste is screened to obtain organic waste. Then, the organic waste is crushed to obtain crushed organic waste. Finally, the crushed organic waste is desalinated to obtain pre-treated household waste.

[0027] In a preferred embodiment, screening includes, but is not limited to, manual primary screening and intelligent fine screening.

[0028] In this invention, manual primary screening includes, but is not limited to, screening and separating construction waste and hazardous waste; intelligent fine screening includes, but is not limited to, automatically classifying waste through near-infrared spectroscopy recognition equipment and AI image recognition system, screening and separating metals, glass and plastics.

[0029] The waste is sorted using a combination of manual initial screening and intelligent fine screening. First, large pieces of construction waste and hazardous waste are removed manually. Then, near-infrared spectroscopy recognition equipment and AI image recognition system are used to automatically classify the waste and accurately separate substances that are not conducive to hydrothermal reactions, such as metals, glass, and plastics (especially chlorinated plastics such as polyvinyl chloride).

[0030] It should be noted that the organic waste obtained after screening includes, but is not limited to, kitchen waste, paper, and at least one of wood, which can be used as raw materials for subsequent hydrothermal reactions, thus improving the efficiency of hydrogen production.

[0031] This invention achieves a reduction rate of municipal solid waste through intelligent sorting and screening and full-process resource utilization, avoiding secondary pollution caused by landfill and incineration; the hydrogen product emits no pollutants after combustion, which helps reduce carbon emissions and improve air quality compared with traditional fossil fuels.

[0032] In a preferred embodiment, crushing includes, but is not limited to, graded crushing.

[0033] In this invention, the graded crushing process includes the following steps: Under the protection of inert gas, the organic waste is first coarsely crushed to a particle size of 20mm-30mm, and then finely crushed to a particle size of 2mm-5mm.

[0034] The organic waste obtained after screening is first coarsely crushed by a jaw crusher (particle size controlled at 20mm-30mm), and then finely crushed by a horizontal shear crusher to ensure that the particle size of the waste particles is uniformly controlled between 2mm-5mm. Inert gas (nitrogen) can be used for protection during the crushing process to avoid oxidation of organic components.

[0035] In a preferred embodiment, the desalination process includes the following steps: The desalination of crushed organic waste is carried out by a combination of water washing and ultrasonic assistance.

[0036] The crushed organic waste is desalinated using a combination of water washing and ultrasonic assistance. The crushed organic waste and deionized water are mixed at a mass ratio of 1:3 to 1:5 and ultrasonically treated for 10 to 15 minutes in an ultrasonic device (power can be set to 300W-500W, frequency can be set to 20kHz-40kHz) while stirring at a speed of 50r / min-80r / min. After ultrasonic treatment, a disc centrifuge (separation factor ≥3000) is used to separate the solid and liquid.

[0037] In this invention, the desalination process, through the coordinated operation of each step and its parameters, enables the desalination rate of waste to reach over 90%, which helps to reduce the corrosion of subsequent reaction equipment and the interference of waste on the reaction process.

[0038] This invention employs a pretreatment process of "intelligent classification + graded crushing + ultrasonic desalination", which significantly improves the purity and reactivity of raw materials. Compared with traditional pretreatment methods, the hydrogen yield is increased by 20%-30%.

[0039] In a preferred embodiment, the specific surface area of ​​Fe2O3-CuO / Al2O3 is ≥150m². 2 / g, the average particle size can be 20nm-30nm, for example, 20nm, 22nm, 24nm, 26nm, 28nm, 30nm, but not limited to these; the pore size distribution of Fe2O3-CuO / Al2O3 is concentrated between 2nm-5nm.

[0040] It should be noted that Fe2O3-CuO / Al2O3 should be reduced and activated in a hydrogen atmosphere before use; The flow rate of hydrogen for reduction and activation can be 50 mL / min to 100 mL / min, for example, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min, 100 mL / min, but is not limited to this; The reduction activation temperature can be 300℃-400℃, for example, 300℃, 320℃, 340℃, 360℃, 380℃, 400℃, but is not limited to this. The time can be 2h-3h, for example, 2h, 2.2h, 2.4h, 2.6h, 2.8h, 3h, but is not limited to this.

[0041] In this invention, the Fe2O3-CuO / Al2O3 catalyst can be prepared by the following method: (1) Carrier pretreatment γ-Al2O3 with a particle size of 50μm-100μm was selected as the support. It was placed in a nitric acid solution with a concentration of 1mol / L-2mol / L and stirred at 60℃-80℃ for 2-3 hours to activate the surface. Then it was washed with deionized water until neutral and dried at 100℃-120℃ for 6-8 hours to obtain the activated Al2O3 support. (2) Preparation of metal salt solutions According to the molar ratio of Fe2O3 to CuO of 3:1, ferric nitrate (Fe(NO3)3)3 was weighed out. 9H2O) and copper nitrate (Cu(NO3)2) Dissolve 3H2O in deionized water to prepare a mixed solution with a total metal ion concentration of 0.5 mol / L to 1 mol / L; Citric acid was added to the resulting mixed solution as a chelating agent. The molar ratio of citric acid to total metal ions was 1.2-1.5:1. The mixture was stirred until completely dissolved to form a homogeneous metal salt-citric acid mixed solution. (3) Sol-gel preparation The activated Al2O3 support was slowly added to the obtained metal salt-citric acid mixed solution. The mass of the Al2O3 support accounted for 30% of the total mass of the catalyst. The mixture was stirred at 50℃-60℃ for 30-60 minutes to fully wet the support. Then, 25%-28% ammonia water was added dropwise to the mixture to adjust the pH value to 6-7. The mixture was stirred for 1-2 hours to form a stable sol. The sol is allowed to stand at 80℃-90℃ to evaporate the water, forming a gel. (4) Drying and roasting The obtained gel was placed in a vacuum drying oven and dried at a vacuum of -0.08 MPa to -0.1 MPa and 80℃ to 100℃ for 12 to 16 hours to remove moisture. The dried gel was then placed in a muffle furnace and heated to 200℃ to 250℃ at a rate of 2℃ / min to 3℃ / min, and held for 2 to 3 hours to decompose organic matter. The temperature was then increased to 500℃ to 600℃ at a rate of 5℃ / min to 6℃ / min, and held for 4 to 6 hours to form a crystalline phase, completing the calcination process. After natural cooling, the gel was ground and sieved (sieve mesh size 100-200 mesh) to obtain the Fe2O3-CuO / Al2O3 catalyst with a specific surface area ≥150 m². 2 / g, with an average particle size of 20nm-30nm and a pore size distribution concentrated between 2nm-5nm; (5) Catalyst activation Before use, the Fe2O3-CuO / Al2O3 catalyst is reduced and activated in a hydrogen atmosphere. The hydrogen flow rate during reduction and activation is 50 mL / min-100 mL / min, the temperature is 300℃-400℃, and the time is 2h-3h, thereby improving the activity of the catalyst and obtaining the activated catalyst.

[0042] The Fe2O3-CuO / Al2O3 catalyst preparation process in this invention is highly innovative. Through steps such as nitric acid activation on the support, citric acid chelation, step-by-step calcination, and hydrogen reduction activation, the catalyst exhibits high selectivity and stability, with a hydrogen selectivity of over 75% and a service life exceeding 50 batches, far surpassing existing single metal oxide catalysts.

[0043] It should be noted that the pretreated domestic waste and deionized water are added to the reactor at a mass ratio of 1:2 to 1:4 to form a uniform slurry, and then the activated catalyst is added (the amount added can be 0.5%-2% of the mass of domestic waste).

[0044] In a preferred embodiment, the separation process includes, but is not limited to, gas-liquid separation, gas purification, and hydrogen purification.

[0045] In this invention, gas-liquid separation includes, but is not limited to, three-stage gas-liquid separation.

[0046] The three-stage gas-liquid separation process includes, but is not limited to, gravity sedimentation separation, cyclone separation, and membrane separation.

[0047] After the reaction products are cooled, they enter a three-stage gas-liquid separator through the liquid outlet of the reactor for three-stage gas-liquid separation. Specifically, the first stage of separation can be gravity sedimentation (retention time of at least 10 min), the second stage of separation can be cyclone separation (separation efficiency ≥ 98%), and the third stage of separation can be membrane separation (membrane pore size 0.1 μm, separation efficiency ≥ 99.5%). The separated liquid mainly contains organic acids, alcohols, and other substances, and enters the subsequent resource recovery system.

[0048] In a preferred embodiment, gas purification can be achieved through water washing or alkaline washing.

[0049] The gas exiting the gas-liquid separator first enters a spray-type water scrubbing tower for water washing and purification. A counter-current washing method can be used. The water scrubbing tower is filled with Pall ring packing (25mm in diameter), and the water flow rate to gas flow rate ratio can be 1:5, thereby effectively removing dust, some organic acids, and impurities such as alcohols from the gas. Then, the gas enters an alkaline scrubbing tower for alkaline washing and purification. A 10%-15% sodium hydroxide solution can be used for washing, and the alkaline solution flow rate to gas flow rate ratio can be 1:8, thereby removing more than 95% of acidic gases such as carbon dioxide, resulting in purified gas.

[0050] In a preferred embodiment, hydrogen purification includes, but is not limited to, using a pressure swing adsorption (PSA) device for hydrogen purification.

[0051] After purification, the gas first enters a molecular sieve dryer (using 3A molecular sieve) to remove moisture (the dew point is lowered to below -40℃), and then enters a pressure swing adsorption (PSA) device for hydrogen purification.

[0052] In this invention, the pressure swing adsorption device can adopt a 4-6 tower process, and the adsorbent can be a novel metal-organic framework material (MOFs, such as HKUST-1). Adsorption is carried out at a pressure of 0.8MPa-1.2MPa for 3-5 minutes. Hydrogen is then recovered by depressurization (to 0.1MPa) and desorption, thereby obtaining a hydrogen product with a purity of over 99.99% and a hydrogen recovery rate of ≥90%.

[0053] It should be noted that the liquid product after gas-liquid separation can be further separated in a distillation tower, and chemical raw materials such as acetic acid (purity ≥98%) and ethanol (purity ≥95%) can be recovered through distillation. In addition, the solid residue at the bottom of the reactor is washed and dried, and then subjected to elemental analysis. If the carbon content is ≥30%, it can be used as a fuel rod feedstock. If the calcium and silicon content is high, it can be used as an additive for building materials.

[0054] This invention employs a three-stage gas-liquid separation and MOFs material PSA purification technology. With the coordinated operation of each step and its process parameters, the purity of the obtained hydrogen can reach over 99.99%, which can meet the requirements of industrial and fuel cell-grade hydrogen.

[0055] According to a second aspect of the present invention, the method for hydrothermal hydrogen production from municipal solid waste as described in any of the preceding claims is provided for application in the resource recovery of solid waste.

[0056] The application of the hydrothermal hydrogen production method for municipal solid waste provided by this invention is beneficial for the resource utilization of solid waste.

[0057] The present invention will be further illustrated below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0058] Example 1 A method for hydrothermal hydrogen production from municipal solid waste includes the following steps: (a) Pre-treatment of municipal solid waste 100 kg of municipal solid waste was collected, and after manual initial screening and intelligent sorting, 50 kg of organic waste was obtained, of which kitchen waste accounted for 55%, paper accounted for 25%, and wood accounted for 20%. Under the protection of inert gas, the organic waste is graded and crushed. Specifically, the organic waste is first coarsely crushed to 25mm, and then finely crushed to 3mm (particle size distribution standard deviation 0.6mm) to obtain crushed organic waste. The crushed organic waste was mixed with 300L of deionized water and treated in a 400W, 30kHz ultrasonic device for 15 minutes, while being stirred at a speed of 60r / min. Then it was separated by a disc centrifuge, with a desalination rate of 92%, to obtain pretreated domestic waste. This step employs a three-stage pretreatment system consisting of intelligent classification and screening, graded crushing, and ultrasonic-assisted desalination. Through an intelligent combination of near-infrared spectral recognition (resolution ≥1nm) and AI image recognition (accuracy ≥95%), it achieves precise removal of interfering substances such as plastics and metals (removal rate ≥99%). Graded crushing, combined with inert gas protection, controls particle size, resulting in more uniform raw materials. Ultrasonic-assisted desalination helps improve the desalination rate, thereby significantly reducing the risk of equipment corrosion. (b) Preparation of Fe2O3-CuO / Al2O3 catalyst (1) Take 50g of γ-Al2O3 support, place it in 1.5mol / L nitric acid solution, stir at 70℃ for 2.5 hours, wash until neutral, and dry at 110℃ for 7 hours; (2) Weigh 48.4gFe(NO3)3 9H2O and 12.1gCu(NO3)2 Dissolve 3H2O in 200mL of deionized water, add 21g of citric acid, and stir to dissolve and form a mixed solution; (3) Add the activated Al2O3 carrier to the mixed solution, stir at 55°C for 45 minutes, add ammonia water to adjust the pH to 6.5, continue stirring for 1.5 hours to form a sol, and let stand at 85°C to evaporate into a gel; (4) The gel was vacuum dried at -0.09 MPa and 90 °C for 14 hours, then heated to 220 °C at 2.5 °C / min and kept at 2.5 °C / min for 2.5 hours, then heated to 550 °C at 5.5 °C / min and kept at 5 hours. After cooling, it was ground through a 150-mesh sieve. (5) Fe2O3-CuO / Al2O3 catalyst was obtained by reducing the hydrogen at a flow rate of 80 mL / min and 350 °C for 2.5 hours. In this step, the support is activated with nitric acid to enhance its surface activity; citric acid chelation technology is used to achieve uniform dispersion of metal ions; a step-by-step calcination process is used to regulate the catalyst's microstructure; and reduction activation is performed under a hydrogen atmosphere to increase the number of catalytic active centers. Finally, the obtained Fe2O3-CuO / Al2O3 catalyst has a specific surface area ≥150 m². 2 / g, with a hydrogen selectivity of over 75% and a service life of over 50 batches; (c) Hydrothermal reaction Pretreated municipal solid waste and 200L of deionized water were added to a 500L titanium alloy coated reactor, and then 0.5kg of Fe2O3-CuO / Al2O3 catalyst was added to form a hydrothermal reaction system. Start the double-layer stirring device, with the inner layer rotating at 100 r / min and the outer layer at 200 r / min; First, a stepwise heating process is carried out, that is, the temperature is increased from room temperature to 150℃ at a rate of 5℃ / min, and then increased from 150℃ to 300℃ at a rate of 8℃ / min, with the final pressure controlled at 12MPa. The reaction was carried out under dynamic constant temperature for another 2 hours, and the hydrogen concentration in the gaseous products was monitored in real time. When the hydrogen concentration dropped to 14%, the stirring speed was increased to 220 r / min and 0.1 kg of catalyst was added. After the reaction is complete, the temperature is gradually reduced to room temperature. First, the temperature is reduced from the reaction temperature to 200℃ at a rate of 8℃ / min, and then from 200℃ to room temperature at a rate of 12℃ / min. The heat is recovered to preheat the deionized water, and the heat recovery rate is 42%. This step employs a comprehensive reaction control mechanism combining stepped heating, dynamic isothermal reaction, and gradient cooling. During the heating phase, two-stage rate control prevents localized overheating. In the isothermal phase, a hydrogen concentration feedback system automatically increases the stirring speed and replenishes the catalyst when the hydrogen concentration is <15%, addressing the issue of activity decay in the later stages of the reaction. The gradient cooling phase, combined with heat recovery technology (recovery rate ≥40%), reduces unit hydrogen energy consumption by 15%-20%. (d) Hydrogen separation and purification After the reaction products are cooled, they enter a three-stage gas-liquid separator through the liquid outlet of the reactor for three-stage gas-liquid separation. Specifically, the first stage of separation uses gravity sedimentation (residence time 10 min), the second stage of separation uses cyclone separation (separation efficiency ≥98%), and the third stage of separation uses membrane separation (membrane pore size 0.1 μm, separation efficiency ≥99.5%). The separated liquid mainly contains organic acids, alcohols and other substances, which enter the subsequent resource recovery system. The gas exiting the gas-liquid separator first enters a spray-type water scrubbing tower for water washing and purification, using a counter-current washing method. The water scrubbing tower is filled with Pall ring packing (25mm in diameter), and the water flow rate to gas flow rate ratio is 1:5, thereby effectively removing dust, some organic acids, and impurities such as alcohols from the gas. Then, the gas enters an alkaline scrubbing tower for alkaline washing and purification, using a 12% sodium hydroxide solution for washing. The alkaline solution flow rate to gas flow rate ratio can be 1:8, thereby removing more than 95% of acidic gases such as carbon dioxide, resulting in purified gas. After purification, the gas is dried by molecular sieve and then enters the PSA unit (4-tower process, using HKUST-1 adsorbent) for hydrogen purification. Adsorption is carried out at a pressure of 1.0 MPa for 4 minutes. Then, the hydrogen is recovered by depressurization (to 0.1 MPa) and desorption, yielding 5.2 kg of hydrogen with a purity of 99.992%, with a hydrogen recovery rate of 91%. The liquid byproducts are recovered by distillation, yielding 1.8 kg of acetic acid (purity 98.5%) and 0.6 kg of ethanol (purity 95.3%). The solid residue is processed and used as fuel rod feedstock. This step employs a purification system consisting of three-stage gas-liquid separation, deep purification, and MOFs material PSA. The three-stage separation (gravity sedimentation, cyclone separation, and membrane separation) achieves a gas-liquid separation efficiency of 99.5%. The combined process of water washing and alkaline washing removes more than 95% of acidic gases. The introduction of MOFs materials such as HKUST-1 as PSA adsorbents ensures hydrogen purity ≥99.99% and recovery rate ≥90%, meeting fuel cell-grade hydrogen standards.

[0059] Example 2 A method for hydrothermal hydrogen production from municipal solid waste includes the following steps: (a) Pre-treatment of municipal solid waste 150kg of municipal solid waste was collected, and after manual initial screening and intelligent sorting, 70kg of organic waste was obtained, of which kitchen waste accounted for 50%, paper accounted for 25%, and wood accounted for 25%. Under the protection of inert gas, the organic waste is graded and crushed. Specifically, the organic waste is first coarsely crushed to 20mm, and then finely crushed to 4mm (particle size distribution standard deviation 0.6mm) to obtain crushed organic waste. The crushed organic waste was mixed with 400L of deionized water and treated in a 500W, 40kHz ultrasonic device for 20 minutes, while being stirred at a speed of 60r / min. Then it was separated by a disc centrifuge, with a desalination rate of 93%, to obtain pretreated domestic waste. (b) Preparation of Fe2O3-CuO / Al2O3 catalyst Same as Example 1; (c) Hydrothermal reaction Pretreated municipal solid waste and 280L of deionized water were added to a 500L titanium alloy coated reactor, and then 1.4kg of Fe2O3-CuO / Al2O3 catalyst was added to form a hydrothermal reaction system. Start the double-layer stirring device, with the inner layer speed at 120 r / min and the outer layer speed at 250 r / min; First, a stepwise heating process is carried out, that is, the temperature is increased from room temperature to 150℃ at a rate of 5℃ / min, and then increased from 150℃ to 320℃ at a rate of 10℃ / min, with the final pressure controlled at 14MPa. The reaction was then carried out under dynamic constant temperature for 1.5 hours, and the hydrogen concentration in the gaseous products was monitored in real time. When the hydrogen concentration dropped to 14%, the stirring speed was increased to 220 r / min and 0.1 kg of catalyst was added. After the reaction is complete, the temperature is gradually reduced to room temperature. First, the temperature is reduced from the reaction temperature to 200℃ at a rate of 8℃ / min, and then from 200℃ to room temperature at a rate of 12℃ / min. The heat is recovered to preheat the deionized water, with a heat recovery rate of 45%. (d) Hydrogen separation and purification After the reaction products are cooled, they enter a three-stage gas-liquid separator through the liquid outlet of the reactor for three-stage gas-liquid separation. Specifically, the first stage of separation uses gravity sedimentation (residence time 10 min), the second stage of separation uses cyclone separation (separation efficiency ≥98%), and the third stage of separation uses membrane separation (membrane pore size 0.1 μm, separation efficiency ≥99.5%). The separated liquid mainly contains organic acids, alcohols and other substances, which enter the subsequent resource recovery system. The gas exiting the gas-liquid separator first enters a spray-type water scrubbing tower for water washing and purification, using a counter-current washing method. The water scrubbing tower is filled with Pall ring packing (25mm in diameter), and the water flow rate to gas flow rate ratio is 1:5, thereby effectively removing dust, some organic acids, and impurities such as alcohols from the gas. Then, the gas enters an alkaline scrubbing tower for alkaline washing and purification, using a 12% sodium hydroxide solution for washing. The alkaline solution flow rate to gas flow rate ratio can be 1:8, thereby removing more than 95% of acidic gases such as carbon dioxide, resulting in purified gas. After purification, the gas is dried by molecular sieve and then enters the PSA unit (4-tower process, using HKUST-1 adsorbent) for hydrogen purification. Adsorption is carried out at a pressure of 1.0 MPa for 4 minutes. The hydrogen is then recovered by depressurization (to 0.1 MPa) and desorption, yielding 7.8 kg of hydrogen with a purity of 99.995% and a hydrogen recovery rate of 92%. The liquid byproducts are recovered by distillation, yielding 2.5 kg of acetic acid (98.8% purity) and 0.9 kg of ethanol (95.5% purity). The solid residue is used as an additive in building materials.

[0060] Example 3 The only difference between this embodiment and Embodiment 1 is that in the pretreatment of domestic waste, the organic waste is first coarsely crushed to 20mm and then finely crushed to 2mm to obtain broken organic waste; The remaining steps and parameters are the same as in Example 1.

[0061] In this embodiment, 5.0 kg of hydrogen with a purity of 99.991% was obtained, and the hydrogen recovery rate was 87.57%.

[0062] Example 4 The only difference between this embodiment and Embodiment 1 is that in the pretreatment of domestic waste, the organic waste is first coarsely crushed to 30mm and then finely crushed to 5mm to obtain broken organic waste. The remaining steps and parameters are the same as in Example 1.

[0063] In this embodiment, 4.9 kg of hydrogen with a purity of 99.99% was obtained, and the hydrogen recovery rate was 85.81%.

[0064] Example 5 The only difference between this embodiment and Embodiment 1 is that, in the hydrothermal reaction, the temperature is first increased from room temperature to 150°C at a rate of 5°C / min, and then increased from 150°C to 250°C at a rate of 8°C / min. The remaining steps and parameters are the same as in Example 1.

[0065] In this embodiment, 4.7 kg of hydrogen gas with a purity of 99.219% was obtained, and the hydrogen recovery rate was 82.31%.

[0066] Example 6 The only difference between this embodiment and Embodiment 1 is that, in the hydrothermal reaction, the temperature is first increased from room temperature to 150°C at a rate of 5°C / min, and then increased from 150°C to 350°C at a rate of 10°C / min. The remaining steps and parameters are the same as in Example 1.

[0067] In this embodiment, 4.8 kg of hydrogen gas with a purity of 99.327% was obtained, and the hydrogen recovery rate was 84.06%.

[0068] Example 7 The only difference between this embodiment and Embodiment 1 is that in the hydrothermal reaction, the dynamic isothermal reaction is carried out for 2 hours, and the hydrogen concentration in the gaseous products is monitored in real time. When the hydrogen concentration drops to 14%, the stirring speed is increased to 230 r / min and 0.2 kg of catalyst is added. The remaining steps and parameters are the same as in Example 1.

[0069] In this embodiment, 4.6 kg of hydrogen gas with a purity of 99.274% was obtained, and the hydrogen recovery rate was 80.56%.

[0070] Example 8 The only difference between this embodiment and Embodiment 1 is that, in the hydrothermal reaction, the gradient cooling to room temperature is first reduced from the reaction temperature to 190°C at a rate of 8°C / min, and then reduced from 190°C to room temperature at a rate of 12°C / min. The remaining steps and parameters are the same as in Example 1.

[0071] In this embodiment, 4.5 kg of hydrogen gas with a purity of 99.197% was obtained, and the hydrogen recovery rate was 78.81%.

[0072] Example 9 The only difference between this embodiment and Embodiment 1 is that, in the hydrothermal reaction, the temperature gradient cooling to room temperature is first reduced from the reaction temperature to 210°C at a rate of 8°C / min, and then reduced from 210°C to room temperature at a rate of 12°C / min. The remaining steps and parameters are the same as in Example 1.

[0073] In this embodiment, 4.4 kg of hydrogen gas with a purity of 99.192% was obtained, and the hydrogen recovery rate was 77.06%.

[0074] Comparative Example 1 The only difference between this comparative example and Example 1 is that step (a) of pretreatment of domestic waste was not performed; The remaining steps and parameters are the same as in Example 1.

[0075] Compared with Example 1, the drawback of this comparative example is that the purity, yield and recovery rate of hydrogen will decrease significantly due to problems such as impurity interference, catalyst failure and reaction runaway, while increasing equipment corrosion and maintenance costs.

[0076] This comparative example yielded 1.3 kg of hydrogen gas with a purity of 99.012%, and the hydrogen recovery rate was 45.45%.

[0077] Comparative Example 2 The only difference between this comparative example and Example 1 is that, in the hydrothermal reaction, Fe2O3 is used instead of Fe2O3-CuO / Al2O3 catalyst; The remaining steps and parameters are the same as in Example 1.

[0078] Compared with Example 1, the drawback of this comparative example is that it will lead to a significant decrease in hydrogen production, purity and recovery rate due to problems such as insufficient active centers, selectivity imbalance and weakened stability, while prolonging the reaction time and reducing the value of by-products.

[0079] This comparative example yielded 2.6 kg of hydrogen gas with a purity of 99.021%, and the hydrogen recovery rate was 57.91%.

[0080] The results demonstrate that the synergistic effect of Fe2O3 and CuO in the composite catalyst and the dispersion stabilization function of the Al2O3 support are the core to achieving efficient hydrogen production, and single-component catalysts cannot replace their comprehensive performance.

[0081] Comparative Example 3 The only difference between this comparative example and Example 1 is that the hydrothermal reaction did not involve a stepwise heating process, but instead directly heated from room temperature to 300°C at a rate of 5°C / min. The remaining steps and parameters are the same as in Example 1.

[0082] Compared with Example 1, the drawback of this comparative example is that it leads to uneven temperature in the reaction system, intensified carbonization of raw materials, impaired catalyst activity and a surge in side reactions, ultimately resulting in a significant decrease in hydrogen purity, yield and recovery rate, while also increasing equipment wear and separation costs.

[0083] This comparative example yielded 2.3 kg of hydrogen gas with a purity of 98.801%, and the hydrogen recovery rate was 56.37%.

[0084] The results show that the stepped heating process, through segmented control of "low-temperature hydrolysis-high-temperature reforming", can ensure efficient conversion of raw materials and stable function of catalysts, while direct heating cannot replace its value in precise control of the reaction process.

[0085] Comparative Example 4 The only difference between this comparative example and Example 1 is that during the dynamic isothermal reaction in the hydrothermal reaction, the hydrogen concentration in the gaseous products was monitored in real time. When the hydrogen concentration dropped to 14%, the stirring speed was not increased and no catalyst was added. The remaining steps and parameters are the same as in Example 1.

[0086] Compared with Example 1, the drawback of this comparative example is that it leads to a decrease in the mass transfer efficiency of the reaction system, irreversible decay of catalyst activity, and runaway side reactions, which ultimately results in a significant decrease in hydrogen purity, yield and recovery rate, while also increasing the difficulty of equipment cleaning and separation costs.

[0087] This comparative example yielded 2.0 kg of hydrogen gas with a purity of 98.500%, and the hydrogen recovery rate was 54.50%.

[0088] The results show that the dynamic feedback mechanism of "stirring speed adjustment and catalyst replenishment" can maintain the efficiency in the later stage of the reaction and ensure the quality of the product.

[0089] Comparative Example 5 The only difference between this comparative example and Example 1 is that the hydrothermal reaction was not subjected to a gradient cooling to room temperature, but was instead cooled directly from the reaction temperature to room temperature at a rate of 8°C / min. The remaining steps and parameters are the same as in Example 1.

[0090] Compared with Example 1, the drawback of this comparative example is that it can cause problems such as reverse product reaction, thermal stress damage to equipment, gas-liquid separation failure and a sharp increase in energy consumption, which ultimately leads to a significant decrease in hydrogen purity, yield and recovery rate, while also increasing equipment maintenance costs and safety risks.

[0091] This comparative example yielded 2.38 kg of hydrogen gas with a purity of 98.902%, and the hydrogen recovery rate was 48.57%.

[0092] The results show that the gradient cooling process can ensure product stability, equipment safety and process economy, while direct cooling cannot replace its value in optimizing the process.

[0093] In summary, this invention removes impurities and optimizes raw material morphology through a three-stage pretreatment process (intelligent sorting + graded crushing + ultrasonic desalination), solving the problems of complex composition and equipment corrosion. It also utilizes a composite catalyst activated by hydrogen reduction to form Fe. 2+ / Cu + The active center, combined with Al2O3 support dispersion, improves catalytic efficiency and acid resistance stability, overcoming the problems of poor catalyst selectivity and easy deactivation. The step-heating-dynamic isothermal-gradient cooling control process, combined with hydrogen concentration feedback regulation, inhibits reverse reaction and by-product formation, solving the problems of low reaction efficiency and uneven product.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for producing hydrogen from municipal solid waste by hydrothermal treatment, characterized by, The method comprises the following steps: The pretreated household garbage is subjected to hydrothermal reaction under the catalysis of Fe2O3-CuO / Al2O3, and the product is separated to obtain the hydrogen gas; The amount of Fe2O3-CuO / Al2O3 accounts for 0.5%-2% of the mass of the household garbage; The hydrothermal reaction comprises a stepwise temperature rising stage, a dynamic constant temperature reaction stage and a gradient temperature falling stage; The stepwise temperature rising stage comprises first rising the temperature from room temperature to 140-160 ℃ at a rate of 4-6 ℃ / min, and then rising the temperature from 140-160 ℃ to 250-350 ℃ at a rate of 8-10 ℃ / min; The dynamic constant temperature reaction stage comprises monitoring the hydrogen concentration in the gaseous product in real time, and when the hydrogen concentration is lower than 15%, the rotating speed is increased by 20-30 r / min and 0.1%-0.2% of the catalyst is added; The gradient temperature falling stage comprises first falling the temperature from the reaction temperature to 190-210 ℃ at a rate of 7-9 ℃ / min, and then falling the temperature from 190-210 ℃ to room temperature at a rate of 11-13 ℃ / min.

2. The method of claim 1, wherein the hydrogen is produced by hydrothermal treatment of the household waste. The pretreatment comprises the following steps: First, the household garbage is screened to obtain organic garbage, and then the organic garbage is crushed to obtain crushed organic garbage, and then the crushed organic garbage is subjected to desalination treatment to obtain the pretreated household garbage.

3. The method of claim 2, wherein the hydrogen is produced by hydrothermal treatment of the household waste. The screening comprises manual preliminary screening and intelligent fine screening; Preferably, the manual preliminary screening comprises screening and separating construction waste and hazardous waste; Preferably, the intelligent fine screening comprises automatically classifying the garbage through a near-infrared spectrum recognition device and an AI image recognition system, and screening and separating metal, glass and plastic; Preferably, the organic garbage comprises at least one of kitchen waste, paper and wood.

4. The method for producing hydrogen from household garbage by hydrothermal process according to claim 2, wherein The crushing comprises a staged crushing treatment; Preferably, the staged crushing treatment comprises the following steps: Under the protection of inert gas, the organic garbage is first coarsely crushed to a particle size of 20-30 mm, and then finely crushed to a particle size of 2-5 mm.

5. The method of claim 2, wherein the waste is selected from the group consisting of food waste, paper waste, plastic waste, and combinations thereof. The desalination treatment comprises the following steps: The crushed organic garbage is subjected to desalination treatment by means of water washing combined with ultrasonic wave assistance; Preferably, the mass ratio of the crushed organic garbage to water is 1:3-1:5; Preferably, the power of the ultrasonic wave is 300-500 W, and the frequency is 20-40 kHz; Preferably, the desalination rate of the desalination treatment is above 90%.

6. The method for producing hydrogen from household garbage by hydrothermal treatment according to any one of claims 1 to 5, wherein The specific surface area of the Fe2O3-CuO / Al2O3 is ≥ 150 m 2 / g, and the average particle size is 20 nm-30 nm; Preferably, the pore size distribution of the Fe2O3-CuO / Al2O3 is concentrated between 2-5 nm.

7. The method of claim 6, wherein the hydrogen is produced by hydrothermal treatment of the household waste. The Fe2O3-CuO / Al2O3 is subjected to reduction activation in a hydrogen atmosphere before use; Preferably, the hydrogen flow rate of the reduction activation is 50-100 mL / min; Preferably, the temperature of the reduction activation is 300-400 ℃, and the time is 2-3 h.

8. The method for producing hydrogen from household garbage by hydrothermal treatment according to any one of claims 1 to 5, wherein The separation comprises gas-liquid separation, gas purification and hydrogen purification in sequence; Preferably, the gas-liquid separation comprises three-stage gas-liquid separation. Preferably, the three-stage gas-liquid separation comprises gravity settling separation, cyclone separation and membrane separation in sequence; Preferably, the residence time of the gravity settling separation is at least 10 min; Preferably, the separation efficiency of the cyclone separation is ≥98%; Preferably, the separation efficiency of the membrane separation is ≥99.5%; Preferably, the gas purification comprises water washing purification and alkali washing purification; Preferably, the hydrogen purification comprises hydrogen purification by a pressure swing adsorption device.

9. The method for hydrothermal hydrogen production from municipal solid waste according to claim 8, characterized in that, The pressure swing adsorption device adopts a 4-6 tower process; Preferably, the adsorbent used by the pressure swing adsorption device comprises a metal organic framework material; Preferably, the metal organic framework material comprises HKUST-1; Preferably, the pressure of the pressure swing adsorption device is 0.8-1.2 MPa, and the adsorption time is 3-5 min.

10. Application of the method for preparing hydrogen from household garbage by hydrothermal process according to any one of claims 1-9 in solid waste resource treatment.