Method for producing hydrogen by gasifying plastic biomass

Abstract

The invention discloses a method for producing hydrogen by gasifying plastic biomass, which comprises the following steps of: physically grading waste plastics according to different types (such as polyethylene, polypropylene, polyvinyl chloride and the like), sorting and treating the waste plastics by adopting an infrared component analyzer, a pyrolysis experiment, laser cutting and other technical means, adjusting the particle size of the waste plastics to be 1-3cm, and carrying out extrusion molding on the waste plastics. And a proper treatment mode is adopted according to pyrolysis characteristics of different plastics, so that the gasification reaction efficiency is improved. Therefore, through fine temperature and atmosphere regulation and control, the hydrogen generation efficiency is improved, the emission of byproducts is reduced, the catalytic efficiency is improved by introducing the composite catalyst, the service life of the catalyst is prolonged, the hydrogen purification process adopts the combination of membrane separation and a temperature swing adsorption method, so that the hydrogen purity reaches 99.99% or above, and the production cost is reduced. According to the technology, the hydrogen yield and purity are remarkably improved, the service life of the catalyst is prolonged, meanwhile, emission of greenhouse gas and harmful by-products is effectively reduced, and remarkable economic and environmental benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of plastic biomass, and in particular to a method for producing hydrogen by gasifying plastic biomass. Background Art

[0002] Waste plastic gasification technology converts waste plastic into usable gases (such as hydrogen, carbon monoxide, methane, etc.) and other valuable chemicals through high-temperature cracking and catalytic reactions. Existing technologies mainly rely on a single catalyst or gasification reaction under a constant atmosphere, using metal catalysts (such as nickel, palladium, etc.) and metal oxide catalysts to promote the cracking and gasification reactions of waste plastics in a high-temperature environment;

[0003] However, the existing technology has many shortcomings. Most methods fail to fully utilize the synergistic effect of the catalyst. During the gasification process, more by-products (such as carbon monoxide, methane, etc.) are generated, and the hydrogen production is low. In addition, since the atmosphere and reaction conditions cannot be dynamically controlled, the catalyst is easily deactivated and has a short service life, resulting in low overall gasification efficiency and poor economy. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, the purpose of the present invention is to propose a method for producing hydrogen by gasifying plastic biomass, a method for producing hydrogen by gasifying waste plastics by combining a composite catalyst with a multi-stage gasification reaction tower. The method improves the gasification efficiency and hydrogen purity by optimizing the multi-stage control of temperature and atmosphere, while reducing the generation of by-products. The catalyst recovery and regeneration technology is used to extend the service life of the catalyst and improve the overall economy.

[0006] To achieve the above object, the present invention proposes a method for producing hydrogen by gasification of plastic biomass, comprising the following steps:

[0007] S1: Pretreatment and classification of waste plastics: Physically classify waste plastics according to different types (such as polyethylene, polypropylene, polyvinyl chloride, etc.), use infrared component analyzer, pyrolysis experiment and laser cutting and other technical means to sort and process waste plastics, adjust their particle size to 1-3cm, and adopt appropriate treatment methods according to the pyrolysis characteristics of different plastics to improve the efficiency of gasification reaction;

[0008] S2: Preparation and introduction of composite catalyst: prepare composite catalyst, the composite catalyst includes a mixed material of metal-based catalysts of palladium, nickel, molybdenum and metal oxides such as titanium and aluminum, the carrier of the catalyst is a high specific surface active material, has high catalytic activity, and can maintain stability at high temperatures, and can effectively catalyze the conversion of hydrocarbons in waste plastics into hydrogen. The preparation method of the catalyst includes a sol-gel method, a precipitation method or a hydrothermal synthesis method to ensure that the catalyst has a stable structure and excellent catalytic performance;

[0009] S3: Multi-stage reaction tower gasification: The pretreated waste plastics and the composite catalyst are sent to the multi-stage reaction tower together. The reaction tower is set up with multiple temperature-controlled reaction zones. The temperature and atmosphere of each reaction zone are different, specifically: low-temperature cracking zone (600℃-700℃), medium-temperature catalytic cracking zone (750℃-850℃) and high-temperature cracking zone (850℃-950℃). By gradually increasing the temperature and adjusting the atmosphere, the hydrogen generation efficiency in the reaction process is maximized, further promoting the cracking and gasification of long-chain hydrocarbons in the waste plastics;

[0010] S4: Dynamic atmosphere control: During the gasification process, the atmosphere in the reaction tower is precisely adjusted to adjust the initial oxygen-rich atmosphere to a nitrogen-rich or hydrogen-rich atmosphere in the middle and late stages, so as to promote efficient gasification and catalytic cracking reactions of waste plastics and reduce the generation of harmful gases. Specifically, an oxygen-rich environment is used in the early stage to promote cracking reactions, and a nitrogen-rich or hydrogen-rich environment is used in the later stage to improve catalytic efficiency, so as to optimize hydrogen yield and reduce the generation of by-products such as carbon monoxide and methane.

[0011] S5: Gas separation and hydrogen recovery: A multi-stage gas separation system is used to separate the gasification products. First, primary membrane separation technology is used to remove gases with larger molecular weights (such as methane, ethylene, etc.). Then, the hydrogen concentration is increased through molecular sieve adsorption, condensation technology and compressed air system. Finally, a high-performance membrane separation system is used to further purify the hydrogen to a purity of more than 99.99%;

[0012] S6: Secondary catalytic cracking and by-product control: In the gasification product, a portion of the organic matter that is not completely gasified is cracked through secondary cracking treatment and further converted into more hydrogen. At the same time, a suitable catalyst (such as molybdenum-based catalyst, nickel-based catalyst, etc.) is added to capture by-products (such as carbon dioxide, methane, etc.), minimize the emission of harmful gases, and improve the economic benefits and environmental friendliness of the gasification process;

[0013] S7: Catalyst recovery and regeneration: The deactivated catalyst in the reaction tower is regularly removed through the high-temperature airflow recovery system, and the catalyst is regenerated with a nitrogen or hydrogen airflow to restore the catalytic activity and ensure the stability and efficiency of the catalyst in long-term use. The catalyst regeneration process uses special regeneration equipment and high-temperature nitrogen or hydrogen to activate the catalyst surface and remove carbon deposits and pollutants;

[0014] S8: Hydrogen purification and further purification: Use multi-stage membrane separation technology to purify the hydrogen in the gas, and finally remove impurities through temperature swing adsorption (VTA) and molecular sieve adsorption to increase the purity of hydrogen to more than 99.99%. The hydrogen purification system can effectively remove residual impurities such as carbon monoxide and methane, ensuring that the final hydrogen output meets industrial application standards;

[0015] S9: Hydrogen collection and transportation: The purified hydrogen is compressed and stored through a high-pressure gas storage system to provide a stable supply of hydrogen for subsequent applications. The hydrogen storage system uses the latest hydrogen storage technology, such as high-pressure hydrogen storage or metal hydride hydrogen storage, to ensure the safe and efficient storage and transportation of hydrogen.

[0016] The method for producing hydrogen by gasifying plastic biomass of the present invention adopts multi-stage reaction tower gasification, composite catalyst, dynamic atmosphere control and other means to optimize the hydrogen yield and purity in the waste plastic gasification process, improves the hydrogen generation efficiency and reduces the emission of by-products through refined temperature and atmosphere control, and the introduction of composite catalyst improves the catalytic efficiency and prolongs the service life of the catalyst. The hydrogen purification process adopts a combination of membrane separation and temperature swing adsorption method to make the hydrogen purity reach more than 99.99%, meeting the needs of industrial applications. The technology significantly improves the hydrogen yield, purity and catalyst life, while effectively reducing the emission of greenhouse gases and harmful by-products, and has significant economic and environmental benefits.

[0017] In addition, the method for producing hydrogen by gasifying plastic biomass according to the present invention may also have the following additional technical features:

[0018] Specifically, the metal components contained in the composite catalyst are palladium, nickel, and molybdenum, and the catalyst carrier is a porous material, such as silicon, aluminum or titanium oxide, which is prepared by a sol-gel method or a precipitation method to ensure a high specific surface area and excellent thermal stability of the catalyst.

[0019] Specifically, the temperature of the reaction zone in the gasification tower is precisely controlled by an electric heating system and an atmosphere control system to ensure that the temperature and atmosphere conditions in each reaction zone are in the optimal reaction range, thereby increasing the hydrogen yield and reducing the generation of by-products.

[0020] Specifically, the gas separation system adopts a combination of membrane separation and compressed air purification technology. In the first stage, a coarse separation membrane is used to remove most impurities, and in the second stage, a fine separation membrane is used to further purify hydrogen, ultimately obtaining hydrogen with a purity of more than 99.99%.

[0021] Specifically, a special molybdenum-based catalyst is used in the secondary cracking reaction, and a high-temperature reaction is used to achieve complete cracking of organic matter, thereby improving the hydrogen recovery efficiency and maximizing the hydrogen production.

[0022] Specifically, the catalyst recovery and regeneration system regenerates the catalyst through a high-temperature gas flow of nitrogen or hydrogen to restore its activity, extend the service life of the catalyst, and maintain its high efficiency and stability.

[0023] Specifically, the hydrogen purification process includes a combination of temperature swing adsorption and membrane separation, so that the purity of hydrogen reaches more than 99.99%, and all possible impurities such as carbon monoxide, methane, etc. can be removed.

[0024] Specifically, the hydrogen yield reaches more than 80% of the mass of the waste plastics, and the hydrogen purity is not less than 99.99%, and the emission of by-products is much lower than that of existing gasification technologies.

[0025] Specifically, the purity of the hydrogen finally produced is as high as 99.99%, and the emission of by-products meets environmental protection standards, especially the emission of greenhouse gases such as CO2 and NOx is greatly reduced.

[0026] Specifically, the hydrogen recovery rate in the gasification process exceeds 85%, and the emission of carbon dioxide and other harmful gases is greatly reduced, which meets the international environmental standards.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0029] Figure 1 This is a schematic diagram of the method for producing hydrogen by gasifying plastic biomass according to the present invention;

[0030] Figure 2 It is a schematic diagram of experimental data of waste plastic classification and particle size adjustment of the present invention;

[0031] Figure 3 Schematic diagram of experimental data of pyrolysis characteristics and treatment methods of waste plastics of the present invention;

[0032] Figure 4It is a schematic diagram of experimental data of gasification reaction efficiency and hydrogen yield of the present invention. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations of the present invention. On the contrary, embodiments of the present invention include all changes, modifications and equivalents that fall within the spirit and connotation of the appended claims.

[0034] The method for producing hydrogen by gasifying plastic biomass according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0035] like Figure 1-Figure 4 As shown, the method for producing hydrogen by gasifying plastic biomass according to the embodiment of the present invention may include the following steps:

[0036] S1. Pretreatment and classification of waste plastics: Physically classify waste plastics according to different types (such as polyethylene, polypropylene, polyvinyl chloride, etc.), use infrared component analyzer, pyrolysis experiment and laser cutting and other technical means to sort and process waste plastics, adjust their particle size to 1-3cm, and adopt appropriate treatment methods according to the pyrolysis characteristics of different plastics to improve the efficiency of gasification reaction.

[0037] It should be noted that in the waste plastic grading process described in this embodiment, an automated sorting system can be introduced to improve grading efficiency and accuracy and ensure that different types of waste plastics are accurately classified. By further optimizing the particle size adjustment process and adopting multi-stage screening and cutting equipment, not only the reaction surface area of ​​the waste plastics is increased, but also the energy consumption in the pretreatment process is reduced. According to the pyrolysis characteristics of different plastics, different pyrolysis pretreatment equipment can be combined to achieve on-demand processing, thereby better adapting to the subsequent gasification reaction and improving the overall reaction rate and hydrogen production.

[0038] S2. Preparation and introduction of composite catalysts: prepare composite catalysts, which include a mixed material of metal-based catalysts of palladium, nickel, and molybdenum and metal oxides such as titanium and aluminum. The carrier of the catalyst is a high specific surface activity material, has high catalytic activity, and can maintain stability at high temperatures, and can effectively catalyze the conversion of hydrocarbons in waste plastics into hydrogen. The preparation method of the catalyst includes a sol-gel method, a precipitation method, or a hydrothermal synthesis method to ensure that the catalyst has a stable structure and excellent catalytic performance.

[0039] It should be noted that the further improvement of the performance of the catalyst described in this embodiment can be achieved by adjusting the metal ratio and selectively doping elements, optimizing the electronic structure and reaction activity of the catalyst, and combining a step-by-step synthesis process. This can not only improve the dispersibility and stability of the catalyst, but also further enhance its high temperature resistance and anti-poisoning ability through post-treatment processes such as high-temperature calcination or surface modification, thereby extending the service life of the catalyst and improving the overall efficiency of the waste plastic gasification reaction.

[0040] S3. Multi-stage reaction tower gasification: The pretreated waste plastics are sent into a multi-stage reaction tower together with a composite catalyst. The reaction tower is set up with multiple temperature-controlled reaction zones. The temperature and atmosphere of each reaction zone are different, specifically: low-temperature cracking zone (600℃-700℃), medium-temperature catalytic cracking zone (750℃-850℃) and high-temperature cracking zone (850℃-950℃). By gradually increasing the temperature and adjusting the atmosphere, the hydrogen generation efficiency in the reaction process is maximized, further promoting the cracking and gasification of long-chain hydrocarbons in the waste plastics.

[0041] It should be noted that in the multi-stage reaction tower described in this embodiment, an air flow velocity and pressure regulation mechanism can be introduced according to the reaction process to optimize the residence time and pyrolysis efficiency of waste plastics in different temperature-controlled reaction zones. By further refining the atmosphere control and temperature regulation and combining the dynamic management of the reaction zone, the atmosphere and temperature distribution of each reaction zone can be optimally configured to maximize the hydrogen yield and reduce the amount of by-products generated.

[0042] It should be understood that in the multi-stage reaction tower, by introducing the air flow velocity and pressure regulation mechanism, the residence time of the waste plastics in each temperature-controlled reaction zone can be accurately controlled, which can usually be adjusted to 5-10 seconds to ensure that the pyrolysis reaction is fully carried out. By real-time monitoring the temperature of each reaction zone (600℃-950℃), the atmosphere is fine-tuned as needed, so that the low-temperature cracking zone (600℃-700℃) mainly cracks macromolecular organic matter, the medium-temperature zone (750℃-850℃) activates the catalyst for cracking, and the high-temperature zone (85 0°C-950℃) helps to completely gasify and optimize the hydrogen yield. Atmosphere regulation maintains the optimal atmosphere in each reaction zone by controlling the ratio of oxygen, nitrogen or hydrogen to ensure a more complete cracking reaction, which can usually increase the hydrogen yield by 20%-30%. During the dynamic management process, sensors and feedback systems are combined to achieve rapid adjustment of the atmosphere and temperature of each reaction zone, ensuring that the amount of by-products (such as carbon monoxide and methane) generated during the gasification process is reduced by more than 50%, significantly improving the cleanliness of the gasification process and hydrogen production.

[0043] S4. Dynamic atmosphere control: During the gasification process, the atmosphere in the reaction tower is precisely adjusted to adjust the initial oxygen-rich atmosphere to a nitrogen-rich or hydrogen-rich atmosphere in the middle and late stages to promote efficient gasification and catalytic cracking reactions of waste plastics and reduce the generation of harmful gases. Specifically, an oxygen-rich environment is used in the early stages to promote cracking reactions, and a nitrogen-rich or hydrogen-rich environment is used in the later stages to improve catalytic efficiency, so as to optimize hydrogen yield and reduce the generation of by-products such as carbon monoxide and methane.

[0044] It should be noted that, in the dynamic atmosphere control process described in this embodiment, real-time sensing technology can be combined to monitor the gas composition during the gasification process, and the atmosphere changes can be accurately adjusted according to the feedback information to ensure a smooth transition of the atmosphere conversion at each stage. By optimizing the introduction strategy of nitrogen-rich and hydrogen-rich atmospheres, the selectivity of the gasification reaction and the hydrogen yield can be further improved, while effectively reducing the generation of unnecessary by-products, thereby improving the overall economy and environmental friendliness of the system.

[0045] It should be understood that the determination of early and mid-to-late stages is based on:

[0046] Initial stage (oxygen-rich atmosphere):

[0047] Time period: Usually in the early stage after the gasification reaction begins, the reaction temperature is low (about 600°

[0048] C-750℃), at which point a large amount of oxygen is needed to promote the cracking reaction of waste plastics. The introduction of oxygen can help decompose long-chain polymers and release small molecular gases for further conversion.

[0049] Judgment basis: Determined by monitoring the temperature and gas composition in the reaction tower. For example, when more hydrocarbons and carbon monoxide are produced during the reaction, it usually means that the gasification reaction is still in the early stages, and a higher oxygen concentration needs to be maintained to promote cracking.

[0050] Mid- to late-stage (nitrogen-rich or hydrogen-rich atmosphere):

[0051] Time period: When the reaction enters the middle to late stages (about 750℃-950℃), the long-chain hydrocarbons of the waste plastics have been partially cracked, and the reaction products are mainly gas, and some long-chain molecules need to be further cracked. In order to reduce the by-products of the oxidation reaction (such as CO, methane, etc.), it is necessary to switch to a nitrogen-rich or hydrogen-rich atmosphere.

[0052] Judgment basis: When the reaction enters the middle and late stages, the hydrogen concentration in the gas gradually increases, the oxygen concentration decreases, and the generation of by-products such as carbon monoxide decreases. At this time, through gas composition analysis and temperature changes, it can be judged whether the conditions for switching to a nitrogen-rich or hydrogen-rich atmosphere have been met.

[0053] The goal of atmosphere adjustment:

[0054] In the initial stage, the oxygen-rich atmosphere helps to accelerate the cracking of waste plastics and reduce the temperature for starting the reaction.

[0055] In the middle and late stages, a nitrogen-rich or hydrogen-rich atmosphere helps improve the catalytic cracking efficiency, while reducing the generation of harmful gases (such as carbon monoxide, methane, etc.) and optimizing the hydrogen recovery efficiency.

[0056] Through the above temperature and gas composition monitoring, the stage of the reaction can be accurately determined, thereby achieving dynamic regulation of the atmosphere to make the reaction more efficient.

[0057] S5. Gas separation and hydrogen recovery: A multi-stage gas separation system is used to separate the gasification products. First, primary membrane separation technology is used to remove larger molecular weight gases (such as methane, ethylene, etc.), and then the hydrogen concentration is increased through molecular sieve adsorption, condensation technology and compressed air system. Finally, a high-performance membrane separation system is used to further purify the hydrogen to a purity of more than 99.99%.

[0058] It should be noted that the gas separation system described in this embodiment adds multiple stages of pretreatment, such as using condensation equipment and pressure regulation to remove large molecular gases in stages and reduce the system load. By optimizing the selectivity of the molecular sieve and adjusting the regeneration cycle of the adsorbent, the hydrogen recovery rate can be effectively improved and the system operation stability can be extended. At the same time, combined with low-energy and high-efficiency membrane separation technology, the hydrogen purification efficiency can be further improved to ensure that energy consumption and costs are reduced while meeting high purity requirements.

[0059] S6: Secondary catalytic cracking and by-product control: In the gasification products, a portion of the organic matter that is not completely gasified undergoes a cracking reaction through secondary cracking treatment and is further converted into more hydrogen. At the same time, suitable catalysts (such as molybdenum-based catalysts, nickel-based catalysts, etc.) are added to capture by-products (such as carbon dioxide, methane, etc.), minimize the emission of harmful gases, and improve the economic benefits and environmental friendliness of the gasification process.

[0060] It should be noted that the introduction of a variety of catalyst combinations in the secondary catalytic cracking stage described in this embodiment not only further improves the conversion rate of incompletely gasified organic matter, but also can selectively capture and treat different by-products to maximize hydrogen yield and reduce the generation of harmful gases such as carbon dioxide and methane, thereby ensuring the high efficiency and sustainability of the gasification process.

[0061] S7: Catalyst recovery and regeneration: The deactivated catalyst in the reaction tower is regularly removed through the high-temperature airflow recovery system, and the catalyst is regenerated with a nitrogen or hydrogen airflow to restore the catalytic activity and ensure the stability and efficiency of the catalyst in long-term use. The catalyst regeneration process uses special regeneration equipment and high-temperature nitrogen or hydrogen to activate the catalyst surface and remove carbon deposits and pollutants.

[0062] It should be noted that in the catalyst recovery and regeneration process described in this embodiment, the catalyst recovery frequency and regeneration process can be optimized in combination with an automated control system, and the catalyst surface activity can be further improved through efficient airflow and temperature control management, thereby reducing energy consumption during the regeneration process and extending the service life of the catalyst, thereby ensuring the long-term stability and efficiency of the gasification reaction.

[0063] S8: Hydrogen purification and further purification: Use multi-stage membrane separation technology to purify the hydrogen in the gas, and finally remove impurities through temperature swing adsorption (VTA) and molecular sieve adsorption to increase the purity of hydrogen to more than 99.99%. The hydrogen purification system can effectively remove residual impurities such as carbon monoxide and methane to ensure that the final output of hydrogen meets industrial application standards. S9, compresses and stores the purified hydrogen through a high-pressure gas storage system to provide a stable supply of hydrogen for subsequent applications. The hydrogen storage system uses the latest hydrogen storage technology, such as high-pressure hydrogen storage or metal hydride hydrogen storage, to ensure the safe and efficient storage and transportation of hydrogen.

[0064] It should be noted that the multi-stage membrane separation and temperature swing adsorption (VTA) combined with molecular sieve adsorption technology described in this embodiment can efficiently remove impurities in hydrogen, such as carbon monoxide and methane, to ensure that the hydrogen purity reaches more than 99.99%, meeting industrial application standards. The purified hydrogen is compressed and stored through a high-pressure gas storage system or metal hydride hydrogen storage technology to ensure safe, efficient storage and stable supply of hydrogen to support subsequent applications.

[0065] The following is a detailed data description combined with the experimental steps:

[0066] Experiment 1: Comparative experiment on waste plastic particle size and gasification efficiency

[0067] Experimental process:

[0068] Waste plastic samples: Waste plastic samples with different particle sizes (including polyethylene, polypropylene and polyvinyl chloride) were used. Their composition was first analyzed by an infrared component analyzer, and then they were cut into different particle sizes using laser cutting technology and divided into three groups: >3cm, 1-3cm, and <1cm.

[0069] a. Pretreatment: Physically classify the waste plastics and adjust their particle size range to the required size. Use pyrolysis experiments to verify the cracking characteristics of waste plastics at different particle sizes.

[0070] b. Gasification experiment: send the waste plastics and composite catalysts (such as palladium, nickel, molybdenum, etc.) into a multi-stage reaction tower for gasification, and set the atmosphere and temperature of different temperature control zones (such as low-temperature cracking zone, catalytic cracking zone, etc.).

[0071] Experimental data such as Figure 2 As shown:

[0072] Gasification hydrogen production: The waste plastic with a particle size of 1-3cm has the highest gasification hydrogen production (150L / kg), which is 25% and 57% higher than the particle size range of >3cm and <1cm, respectively. This is because the medium-sized waste plastic can better contact with the catalyst during the gasification process, promote the gasification reaction, and improve the gasification efficiency.

[0073] Hydrogen purity: The hydrogen purity of waste plastics with medium particle size (1-3 cm) is 90%, which is much higher than that of the other two groups. This shows that at the appropriate particle size, the catalytic cracking reaction is more efficient and less by-products are generated.

[0074] Byproduct generation: Compared with waste plastics >3 cm, the generation of byproducts (such as CO and CH4) of waste plastics 1-3 cm is greatly reduced, indicating that appropriate particle size optimization can effectively reduce the generation of harmful byproducts.

[0075] Specifically, by optimizing the particle size of waste plastics, the gasification efficiency and hydrogen purity can be significantly improved, and the generation of by-products can be reduced. The prior art generally ignores the effect of the particle size of waste plastics on the gasification efficiency, while the present invention improves the efficiency of the gasification reaction and the hydrogen yield through particle size classification, and reduces the generation of by-products in traditional gasification technology.

[0076] Experiment 2: Comparative experiment on waste plastic types and pyrolysis treatment methods

[0077] Experimental process:

[0078] a. Type of waste plastics: Three different types of waste plastics, polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC), were selected and pyrolysis experiments were carried out to study the pyrolysis behaviors of different types of plastics at different temperatures.

[0079] b. Temperature control setting: Set different temperature control reaction zones (low temperature: 600°C, catalytic cracking: 750°C, high temperature: 900°C), and set a specific atmosphere in each zone for gasification treatment.

[0080] c. Catalyst selection: Use metal-based catalysts such as palladium, nickel, molybdenum and composite catalysts of metal oxides for combined treatment.

[0081] Experimental data such as Figure 3 As shown:

[0082] Result analysis:

[0083] Hydrogen production: Polyethylene (PE) has the highest hydrogen production (170L / kg) at 750°C, indicating that PE plastic is most efficiently pyrolyzed at this temperature. Polypropylene (PP) and polyvinyl chloride (PVC) are slightly lower, but still show good hydrogen generation capabilities.

[0084] By-product generation: Polyethylene has the lowest by-product generation, with carbon monoxide and methane generated at 30g / kg and 25g / kg respectively, which are significantly lower than PP and PVC.

[0085] Hydrogen purity: The hydrogen purity of polyethylene reaches 89%, which is relatively high, and the amount of by-products generated is relatively small, which shows that it has good selectivity as a gasification feedstock.

[0086] Specifically, by selecting a suitable type of waste plastic (such as PE) and adjusting a suitable pyrolysis temperature, the present invention can effectively control the generation of by-products while maintaining a relatively high hydrogen yield, thereby solving the problem of excessive by-product generation in the prior art.

[0087] Experiment 3: Comparative experiment between traditional gasification technology and the technical solution of the present invention

[0088] Experimental process:

[0089] a. Experimental setup: The conventional single catalyst gasification technology and the composite catalyst multi-stage gasification scheme of the present invention were used to gasify waste plastics, and the hydrogen production, hydrogen purity and by-product generation were recorded.

[0090] b. Gasification conditions: The temperature control zones are set as low temperature, catalytic cracking, and high temperature zones, and the atmosphere is adjusted according to the reaction progress.

[0091] Experimental data such as Figure 4 As shown:

[0092] Result analysis:

[0093] Hydrogen yield: The hydrogen yield of the technical solution of the present invention reaches 180L / kg, which is 50% higher than that of the traditional gasification technology. This proves that the combined application of multi-stage temperature control reaction and composite catalyst can greatly improve the gasification efficiency of waste plastics.

[0094] Hydrogen purity: The hydrogen purity of the present invention is 92%, which is 7 percentage points higher than the conventional technology (85%), indicating that the scheme has obvious advantages in optimizing hydrogen purity.

[0095] By-product generation: The carbon monoxide and methane generated by the technical solution of the present invention are reduced to 20g / kg and 10g / kg respectively, which is significantly reduced compared with traditional gasification technology, indicating that this technology is more efficient in controlling by-products.

[0096] Specifically, through composite catalysts, multi-stage reaction towers, and fine control of the atmosphere and temperature, the hydrogen production and purity are effectively increased, and the generation of by-products is significantly reduced, fundamentally solving the problems of low hydrogen production, insufficient purity, and excessive by-products in the prior art.

[0097] It should be noted that the gasification efficiency and hydrogen production are significantly improved through particle size classification, waste plastic type selection and multi-stage reaction tower optimization described in this embodiment. Experimental data show that appropriate particle size and fine control of the temperature-controlled reaction zone can minimize the formation of by-products and improve the purity of hydrogen. In addition, the introduction of the composite catalyst combined with atmosphere regulation not only enhances the catalytic effect, but also effectively controls the emission of harmful gases, thereby optimizing the overall efficiency and environmental friendliness of the gasification process.

[0098] Specifically, through the pretreatment and classification of waste plastics, the waste plastics are physically classified according to their types and pyrolysis characteristics, and the particle size is adjusted to 1-3 cm to improve the efficiency of the gasification reaction. On this basis, a composite catalyst (such as a mixed material of metal-based catalysts such as palladium, nickel, and molybdenum and metal oxides) is used to enhance the ability of hydrocarbons in waste plastics to be converted into hydrogen and ensure the stability of the catalyst at high temperatures. The waste plastics are fed into a multi-stage reaction tower together with the catalyst, and are gasified and cracked through the step-by-step temperature-controlled reaction zones of the low-temperature cracking zone, the medium-temperature catalytic cracking zone, and the high-temperature cracking zone. The atmosphere and temperature are finely controlled to maximize the hydrogen production and Minimize by-products, and ensure the high efficiency, environmental protection and high purity of hydrogen in the gasification process through dynamic atmosphere control, secondary catalytic cracking, catalyst recovery and regeneration, and hydrogen purification technologies, solving the problems of low hydrogen production and excessive by-product generation in existing waste plastic gasification technologies. Experimental results show that refined atmosphere and temperature control management greatly improve the production and purity of hydrogen and effectively reduce the generation of harmful gases. At the same time, the use of composite catalysts extends the service life of the catalyst and improves the efficiency of the gasification reaction. Through these technological innovations, the present invention breaks through the bottleneck of the prior art and improves the overall efficiency of the waste plastic gasification process.

[0099] In one embodiment of the present invention, Figure 1-Figure 4 As shown, the metal components contained in the composite catalyst are palladium, nickel, and molybdenum, and the catalyst carrier is a porous material, such as silicon, aluminum or titanium oxide, and is prepared by a sol-gel method or a precipitation method to ensure a high specific surface area and excellent thermal stability of the catalyst. The temperature of the reaction zone in the gasification tower is precisely controlled by an electric heating system and an atmosphere control system to ensure that the temperature and atmosphere conditions in each reaction zone are in the optimal reaction range, thereby increasing the hydrogen yield and reducing the generation of by-products. The gas separation system adopts a combination of membrane separation and compressed air purification technology. In the first stage, a coarse separation membrane is used to remove most of the impurities, and in the second stage, a fine separation membrane is used to further purify the hydrogen, ultimately obtaining hydrogen with a purity of more than 99.99%.

[0100] It should be noted that the conversion efficiency of the waste plastic gasification process is further improved by optimizing the composition and preparation process of the composite catalyst described in this embodiment, combined with precise temperature control of the reaction zone and atmosphere regulation. At the same time, the multi-stage gas separation technology is used to ensure the stable output of high-purity hydrogen, thereby significantly improving the economic benefits and environmental friendliness of the overall gasification process.

[0101] In one embodiment of the present invention, Figure 1-Figure 4 As shown, a special molybdenum-based catalyst is used in the secondary cracking reaction, and the organic matter is completely cracked by a high-temperature reaction, the recovery efficiency of hydrogen is improved, and the hydrogen production is maximized. The catalyst recovery and regeneration system regenerates the catalyst by a high-temperature gas flow of nitrogen or hydrogen to restore its activity, extend the service life of the catalyst, and maintain its high efficiency and stability. The hydrogen purification process includes a combination of temperature swing adsorption and membrane separation, so that the purity of hydrogen reaches more than 99.99%, and all possible impurities such as carbon monoxide and methane can be removed. The hydrogen yield reaches more than 80% of the mass of the waste plastic, and the hydrogen purity is not less than 99.99%. The emission of by-products is much lower than that of the existing gasification technology. The purity of the hydrogen finally produced is as high as 99.99%, and the emission of by-products meets environmental protection standards, especially the emission of greenhouse gases such as CO2 and NOx is greatly reduced. The hydrogen recovery rate in the gasification process exceeds 85%, and the emission of carbon dioxide and other harmful gases is greatly reduced, which meets international environmental standards.

[0102] It should be noted that the embodiment described in this embodiment not only effectively improves the hydrogen recovery efficiency by introducing a molybdenum-based catalyst and a high-temperature secondary cracking reaction, but also maximizes the hydrogen production while reducing the generation of harmful by-products. The catalyst recovery and regeneration system is treated by a high-temperature nitrogen or hydrogen gas flow to ensure the long-term use and stability of the catalyst, and reduce the frequency and cost of catalyst replacement. The hydrogen purification process combines temperature swing adsorption with membrane separation to stabilize the hydrogen purity at more than 99.99%, while effectively removing impurities such as CO and methane to ensure that the final product meets industrial application standards. This technical solution significantly improves the hydrogen recovery rate and purity, significantly reduces by-product emissions, meets international environmental protection standards, and enhances the economy and sustainability of the technology.

[0103] In summary, the method for producing hydrogen by gasification of plastic biomass in the embodiment of the present invention adopts multi-stage reaction tower gasification, composite catalyst, dynamic atmosphere control and other means to optimize the hydrogen yield and purity in the gasification process of waste plastics. Through refined temperature and atmosphere control, the hydrogen generation efficiency is improved and the emission of by-products is reduced. The introduction of the composite catalyst improves the catalytic efficiency and extends the service life of the catalyst. The hydrogen purification process adopts a combination of membrane separation and temperature swing adsorption method to make the hydrogen purity reach more than 99.99%, which meets the needs of industrial applications. This technology significantly improves the hydrogen production, purity and catalyst life, while effectively reducing the emission of greenhouse gases and harmful by-products, and has significant economic and environmental benefits.

[0104] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0105] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0106] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and deform the above embodiments within the scope of the present invention.

Claims

1. A method for producing hydrogen by gasification of plastic biomass, characterized in that: The following steps are involved: S1: Pretreatment and classification of waste plastics: Physically classify waste plastics according to different types (such as polyethylene, polypropylene, polyvinyl chloride, etc.), use infrared component analyzer, pyrolysis experiment and laser cutting and other technical means to sort and process waste plastics, adjust their particle size to 1-3cm, and adopt appropriate treatment methods according to the pyrolysis characteristics of different plastics to improve the efficiency of gasification reaction; S2: Preparation and introduction of composite catalyst: prepare composite catalyst, the composite catalyst includes a mixed material of metal-based catalysts of palladium, nickel, molybdenum and metal oxides such as titanium and aluminum, the carrier of the catalyst is a high specific surface active material, has high catalytic activity, and can maintain stability at high temperatures, and can effectively catalyze the conversion of hydrocarbons in waste plastics into hydrogen. The preparation method of the catalyst includes a sol-gel method, a precipitation method or a hydrothermal synthesis method to ensure that the catalyst has a stable structure and excellent catalytic performance; S3: Multi-stage reaction tower gasification: The pretreated waste plastics and the composite catalyst are sent to the multi-stage reaction tower together. The reaction tower is set up with multiple temperature-controlled reaction zones. The temperature and atmosphere of each reaction zone are different, specifically: low-temperature cracking zone (600℃-700℃), medium-temperature catalytic cracking zone (750℃-850℃) and high-temperature cracking zone (850℃-950℃). By gradually increasing the temperature and adjusting the atmosphere, the hydrogen generation efficiency in the reaction process is maximized, further promoting the cracking and gasification of long-chain hydrocarbons in the waste plastics; S4: Dynamic atmosphere control: During the gasification process, the atmosphere in the reaction tower is precisely adjusted to adjust the initial oxygen-rich atmosphere to a nitrogen-rich or hydrogen-rich atmosphere in the middle and late stages, so as to promote efficient gasification and catalytic cracking reactions of waste plastics and reduce the generation of harmful gases. Specifically, an oxygen-rich environment is used in the early stage to promote cracking reactions, and a nitrogen-rich or hydrogen-rich environment is used in the later stage to improve catalytic efficiency, so as to optimize hydrogen yield and reduce the generation of by-products such as carbon monoxide and methane. S5: Gas separation and hydrogen recovery: A multi-stage gas separation system is used to separate the gasification products. First, primary membrane separation technology is used to remove gases with larger molecular weights (such as methane, ethylene, etc.). Then, the hydrogen concentration is increased through molecular sieve adsorption, condensation technology and compressed air system. Finally, a high-performance membrane separation system is used to further purify the hydrogen to a purity of more than 99.99%; S6: Secondary catalytic cracking and by-product control: In the gasification product, a portion of the organic matter that is not completely gasified is cracked through secondary cracking treatment and further converted into more hydrogen. At the same time, a suitable catalyst (such as molybdenum-based catalyst, nickel-based catalyst, etc.) is added to capture by-products (such as carbon dioxide, methane, etc.), minimize the emission of harmful gases, and improve the economic benefits and environmental friendliness of the gasification process; S7: Catalyst recovery and regeneration: The deactivated catalyst in the reaction tower is regularly removed through the high-temperature airflow recovery system, and the catalyst is regenerated with a nitrogen or hydrogen airflow to restore the catalytic activity and ensure the stability and efficiency of the catalyst in long-term use. The catalyst regeneration process uses special regeneration equipment and high-temperature nitrogen or hydrogen to activate the catalyst surface and remove carbon deposits and pollutants; S8: Hydrogen purification and further purification: Use multi-stage membrane separation technology to purify the hydrogen in the gas, and finally remove impurities through temperature swing adsorption (VTA) and molecular sieve adsorption to increase the purity of hydrogen to more than 99.99%. The hydrogen purification system can effectively remove residual impurities such as carbon monoxide and methane, ensuring that the final hydrogen output meets industrial application standards; S9: Hydrogen collection and transportation: The purified hydrogen is compressed and stored through a high-pressure gas storage system to provide a stable supply of hydrogen for subsequent applications. The hydrogen storage system uses the latest hydrogen storage technology, such as high-pressure hydrogen storage or metal hydride hydrogen storage, to ensure the safe and efficient storage and transportation of hydrogen.

2. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The metal components contained in the composite catalyst are palladium, nickel and molybdenum, and the catalyst carrier is a porous material, such as silicon, aluminum or titanium oxide, and is prepared by a sol-gel method or a precipitation method to ensure a high specific surface area and excellent thermal stability of the catalyst.

3. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The temperature of the reaction zone in the gasification tower is precisely controlled by an electric heating system and an atmosphere control system to ensure that the temperature and atmosphere conditions in each reaction zone are in the optimal reaction range, thereby increasing the hydrogen yield and reducing the generation of by-products.

4. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The gas separation system adopts a combination of membrane separation and compressed air purification technology. In the first stage, a coarse separation membrane is used to remove most impurities, and in the second stage, a fine separation membrane is used to further purify hydrogen, ultimately obtaining hydrogen with a purity of more than 99.99%.

5. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: A special molybdenum-based catalyst is used in the secondary cracking reaction, and a high-temperature reaction is used to achieve complete cracking of organic matter, thereby improving the hydrogen recovery efficiency and maximizing the hydrogen production.

6. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The catalyst recovery and regeneration system regenerates the catalyst through a high-temperature gas flow of nitrogen or hydrogen to restore its activity, extend the service life of the catalyst, and maintain its high efficiency and stability.

7. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The hydrogen purification process includes a combination of temperature swing adsorption and membrane separation, so that the purity of hydrogen reaches more than 99.99%, and all possible impurities such as carbon monoxide, methane, etc. can be removed.

8. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The hydrogen yield reaches more than 80% of the mass of the waste plastics, and the purity of the hydrogen is not less than 99.99%, and the emission of by-products is much lower than that of the existing gasification technology.

9. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The purity of the hydrogen finally produced is as high as 99.99%, and the emission of by-products meets environmental protection standards, especially the emission of greenhouse gases such as CO2 and NOx is greatly reduced.

10. The method for producing hydrogen by gasification of plastic biomass according to claim 1, characterized in that: The hydrogen recovery rate in the gasification process exceeds 85%, and the emission of carbon dioxide and other harmful gases is greatly reduced, which meets the international environmental standards.

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