Method for producing green hydrogen and in-situ hydrogen storage from biomass
By inducing the gasification of biomass charcoal into steam and reacting it with atmospheric pressure to synthesize ammonia, the problems of low efficiency in traditional biomass hydrogen production and high energy consumption in ammonia synthesis have been solved, achieving efficient and safe hydrogen production and storage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF CHEM IND OF FOREST PROD CHINESE ACAD OF FORESTRY
- Filing Date
- 2024-02-29
- Publication Date
- 2026-05-22
AI Technical Summary
In traditional biomass hydrogen production processes, hydrogen production efficiency and controllability are insufficient, and traditional ammonia synthesis processes require high temperature and high pressure, resulting in high energy consumption and significant environmental impact.
Hydrogen production is achieved by using frequency-converting microwave-induced biomass char steam gasification. The optimal absorption frequency of the coupled catalyst is controlled by microwave frequency regulation to realize the reaction of biomass char steam gasification with ammonia synthesis under normal pressure. The activation energy is reduced and the reaction rate is increased by utilizing resonance and hot spot effects to achieve hydrogen storage under normal pressure.
It improves hydrogen production efficiency, enables safe and efficient hydrogen storage, reduces reaction activation energy, minimizes environmental impact, and provides an economical and efficient hydrogen production and storage solution.
Smart Images
Figure CN118206072B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrogen production and storage technology, specifically relating to a method for producing green hydrogen from biomass and storing hydrogen in situ. Background Technology
[0002] In recent years, with the increasing demand for clean energy, hydrogen, as an energy medium with potential renewability and low carbon emissions, has attracted much attention. Biomass gasification for hydrogen production is an important means of hydrogen energy production, but the efficiency and controllability of biomass-to-hydrogen conversion in traditional hydrogen production processes have always been pressing issues. Against this backdrop, microwave technology, as an emerging and innovative energy conversion technology, has attracted widespread attention and is gradually being applied to the field of biomass-to-green hydrogen production. Microwaves can rapidly and selectively heat catalysts, thereby increasing the reaction rate. Furthermore, it has been proven that microwaves can reduce the activation energy required for the reaction. However, current microwave emission frequencies are generally around 2450 MHz. Different materials have different intrinsic frequencies and absorption characteristics, making it difficult to achieve high-rate heating of various catalytic materials with a fixed microwave frequency.
[0003] Biomass gasification products contain gases such as CO and CO2, which, when stored as compounds like toluene, typically require synthesis from pure hydrogen. Ammonia, as an important form of hydrogen storage, has wide applications in agriculture and industry, such as in the production of nitrogen fertilizers or various chemical products like nitric acid, urea, and ammonia water. The Haber-Bosch process is a widely used industrial method for ammonia synthesis. The Haber-Bosch process requires operation at high temperatures (400-520℃) and high pressures (150-250 bar), making it a high-energy-intensive process. Effective catalysts play a crucial role in this process, typically metals and metal oxides, to promote the reaction. Therefore, improving the ammonia synthesis process to increase energy efficiency and reduce environmental impact is a key research direction. Summary of the Invention
[0004] To address the aforementioned problems in existing technologies, this invention aims to provide a method for biomass-based green hydrogen production and in-situ hydrogen storage. This method constructs a reaction system that integrates frequency-modulated microwave-induced biomass charcoal steam gasification for hydrogen production, followed by ammonia synthesis and hydrogen storage. By adjusting the microwave frequency to couple the optimal absorption frequency of the catalyst, and leveraging resonance and hotspot effects, the activation energy of the gasification reaction is effectively reduced, the reaction rate is increased, the gas composition is adjusted, and the goal of atmospheric pressure ammonia synthesis is achieved. This method not only improves the efficiency of hydrogen production but also plays a positive role in atmospheric pressure hydrogen storage research, making the hydrogen storage process safer and more efficient. It provides strong technical support for achieving clean and efficient hydrogen production and in-situ storage, and has broad application prospects.
[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:
[0006] A method for producing green hydrogen from biomass and storing hydrogen in situ involves using biochar as a microwave absorber and reactant, and water being gasified in a preheating furnace and then introduced into a microwave reactor. Water vapor passes from top to bottom through the char bed to produce syngas through a water-gas reaction.
[0007] An α-Fe catalyst is connected in series in the lower layer of biochar. The resulting syngas reacts with N2 at atmospheric pressure under α-Fe catalysis in a microwave reactor with adjustable microwave frequency to generate NH3, and H2 is stored in the form of safe NH3 compounds.
[0008] The method for producing green hydrogen from biomass and storing hydrogen in situ, when using biochar as a microwave absorber and reactant, uses a microwave frequency of 2450-5525MHz and a power of 100W.
[0009] The method for producing green hydrogen from biomass and storing hydrogen in situ produces H2 with a volume fraction of 52%-60.7% and CO with a volume fraction of 22.8%-45.8% from the steam gasification of biomass charcoal.
[0010] The method for biomass-based green hydrogen production and in-situ hydrogen storage uses α-Fe as a microwave absorber and catalyst, with a microwave frequency of 2450-5525MHz, a power of 100W, and a space velocity of 1200-3600h. -1 The reaction temperature is 303-560℃; preferably, the microwave frequency is 5400MHz and the reaction temperature is 303℃.
[0011] The method for producing green hydrogen from biomass and storing it in situ includes the following steps:
[0012] The first step is to fill the quartz tube with quartz wool, and then fill the quartz tube with α-Fe and biochar in sequence, and fix them with quartz wool.
[0013] The second step is to connect the quartz tube to the reaction system, check the airtightness, purge the reaction system with nitrogen and keep the reactor in an inert atmosphere.
[0014] The third step is to turn on the microwave power supply and input the frequency-converted microwave into the microwave resonant cavity through the microwave feed port. After the absorbing material absorbs microwaves of different frequencies, it begins to heat up. The temperature change of the catalyst is detected in real time by an infrared thermometer and a thermal imager on the axial section of the quartz tube.
[0015] Step 4: After reaching and stabilizing the reaction temperature, water is vaporized in a preheating furnace at a predetermined flow rate and then introduced into the reactor.
[0016] Step 5: After the reaction is complete, collect the gaseous products.
[0017] The method for producing green hydrogen from biomass and storing hydrogen in situ uses water with a flow rate of 0.2 ml / min, a vaporization temperature of 100-250℃, and a nitrogen flow rate of 20 ml / min.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0019] 1. This invention fully utilizes the selective coupling characteristics of microwave frequencies to absorbing materials, innovatively constructing a reaction system for the production of green hydrogen from biomass and in-situ atmospheric pressure hydrogen storage using frequency-converting microwave-induced biomass. Based on frequency-converting microwave-induced biomass charcoal steam vaporization and atmospheric pressure ammonia synthesis, this system achieves efficient one-step hydrogen production while simultaneously enabling in-situ atmospheric pressure hydrogen storage. This not only improves the efficiency of biomass charcoal-based hydrogen production but also emphasizes the importance of hydrogen storage in the entire energy conversion process, contributing a sustainable and far-reaching impact to the development of hydrogen energy technology.
[0020] 2. Based on the continuously adjustable characteristics of microwave frequency, this invention studies the coupling characteristics between microwave frequency and biochar material, reduces the reaction activation energy, and rapidly heats biochar to carry out water-gas reaction when the microwave frequency is 4450MHz. The resulting syngas integral is greater than 99%, and the hydrogen-carbon molar ratio is 1.2, thereby realizing the full conversion of microwave activated carbon catalytic cracking into syngas and improving the quality of syngas.
[0021] 3. This invention successfully achieves in-situ hydrogen storage through a series catalytic ammonia synthesis reaction, eliminating the need for gas separation. This innovation solves the problems of difficulty in water-gas reaction under traditional microwave frequencies, low gas production rate under electric heating conditions, and the complexity and separation difficulties of syngas components.
[0022] 4. Based on the continuous frequency tuning characteristic of variable frequency microwave, this invention effectively reduces the reaction pressure by changing the microwave frequency to couple the optimal absorption frequency of the catalyst under the influence of resonance and hot spot effects. This induces the hydrogen-rich gas obtained from biomass gasification to undergo a Haber-Bosch reaction with nitrogen under normal pressure conditions of 0.1 MPa to synthesize ammonia, thus achieving safe and green hydrogen storage.
[0023] 5. The reaction process of this invention uses a commercial Fe-based catalyst, which overcomes the problems of high pressure and expensive catalysts required for the synthesis of ammonia in traditional hydrogen storage technology. It provides a more economical and efficient solution for the preparation of green hydrogen and atmospheric pressure hydrogen storage, with the highest NH3 concentration reaching 31.5 ppm. Attached Figure Description
[0024] Figure 1 Flowchart of the reaction system for frequency conversion microwave-induced biomass preparation of green hydrogen and in-situ atmospheric pressure hydrogen storage;
[0025] Figure 2 The graph shows the effect of microwaves and microwave frequencies on ammonia synthesis.
[0026] Figure 3 The graph shows the effect of CO volume fraction on ammonia synthesis. Detailed Implementation
[0027] The present invention will be further described below with reference to specific embodiments. The microwave continuous frequency modulation device used in the embodiments is disclosed in a microwave continuous frequency modulation synergistic biomass directional depolymerization device and its usage method (CN 111117676A).
[0028] Example 1
[0029] The reaction system for frequency conversion microwave-induced biomass-based green hydrogen production and in-situ atmospheric pressure hydrogen storage is as follows: Figure 1 As shown, in a microwave reactor, with a frequency of 2450MHz and a power of 100W, 2g of α-Fe and 3g of biochar were used as microwave absorbers and catalysts, respectively, to investigate the effect of microwave frequency on gasification for hydrogen production and ammonia synthesis. Control of the amounts of α-Fe and biochar: α-Fe is a catalyst and is not consumed during the reaction; its amount only needs to be controlled to ensure sufficient microwave absorption and coverage of the temperature measurement area. Biochar, as a reactant, decreases as the reaction progresses; therefore, it should be filled as much as possible within the limited height of the quartz tube. In this example, maintaining the same filling height for both was considered the standard.
[0030] The water flow rate is 0.2 ml / min, and the water vaporization temperature is 250°C. Water is one of the reactants in the vaporization reaction and has a direct impact on the hydrogen yield and volume fraction. Generally, the hydrogen yield increases and then decreases with the water flow rate, usually not exceeding 1 ml / min. The flow rate selected in this example is the minimum flow rate to ensure the reaction occurs. The water vaporization temperature only needs to ensure that the water enters the system in the form of steam, i.e., above 100°C. The temperature selected in this example is the highest temperature of the gasifier, so that the steam is in a superheated state to compensate for the heat loss between the gasifier and the quartz tube.
[0031] The specific implementation steps include:
[0032] The first step is to fill a quartz tube with an inner diameter of 8mm with quartz wool, and then fill the quartz tube with 2g of α-Fe and 3g of activated carbon and fix them in place with quartz wool.
[0033] The second step is to connect the quartz tube to the reaction system, check the airtightness, purge the reaction system with nitrogen and keep the reactor in an inert atmosphere.
[0034] The third step is to turn on the microwave power supply and input the frequency-converted microwave into the microwave resonant cavity through the microwave feed port. After the catalyst absorbs the microwave, it begins to heat up. The temperature change of the catalyst is detected in real time by an infrared thermometer and a thermal imager at the axial section of the quartz tube.
[0035] Step 4: After reaching and stabilizing the reaction temperature, adjust the nitrogen flow rate to 20 ml / min, and adjust the flow meter to control the water flow rate to 0.2 ml / min after it has been vaporized in the preheating furnace and then introduced into the reactor.
[0036] Step 5: Collect gaseous products using a gas sampling bag and analyze them offline in a gas chromatograph.
[0037] In this embodiment, the temperature of the catalytic bed is below 200°C, and the gasification reaction does not occur.
[0038] Example 2
[0039] In the microwave reactor, the microwave power was set to 100W and the frequency to 4200MHz, and other conditions and implementation steps were the same as in Example 1.
[0040] In this embodiment, the catalytic bed temperature is 527°C, and at a frequency of 4200MHz, the composition and volume fraction of the gasification products are H2: 52%, CO: 44.5%, CO2: 3.5%, and NH3 concentration is 14.6ppm.
[0041] Example 3
[0042] In the microwave reactor, the microwave power was set to 100W and the frequency to 4225MHz. Other conditions and implementation steps were the same as in Example 1.
[0043] In this embodiment, the catalytic bed temperature is 450°C, and the composition of the gasification product at a frequency of 4225 MHz is H2: 58.2%, CO: 34.5%, CO2: 7.3%, and NH3 concentration is 13.9 ppm.
[0044] Example 4
[0045] In the microwave reactor, the microwave power was set to 100W and the frequency to 4450MHz. Other conditions and implementation steps were the same as in Example 1.
[0046] In this embodiment, the catalytic bed temperature is 560°C, and at a frequency of 4450MHz, the composition and volume fraction of the gasification products are H2: 53.6%, CO: 45.8%, CO2: 0.6%, and NH3 concentration is 21.9ppm.
[0047] Example 5
[0048] In the microwave reactor, the microwave power was set to 100W and the frequency to 5175MHz. Other conditions and implementation steps were the same as in Example 1.
[0049] In this embodiment, the catalytic bed temperature was 307°C, and at a frequency of 5175MHz, the composition and volume fraction of the gasification products were H2: 56.8%, CO: 29.6%, CO2: 13.6%, and NH3 concentration was 15.8ppm.
[0050] Example 6
[0051] In the microwave reactor, the microwave power was set to 100W and the frequency to 5400MHz, and other conditions and implementation steps were the same as in Example 1.
[0052] In this embodiment, the catalytic bed temperature is 303°C, and at a frequency of 5400MHz, the composition and volume fraction of the gasification products are H2: 60.7%, CO: 22.8%, CO2: 16.5%, and NH3 concentration is 31.5ppm.
[0053] Example 7
[0054] In the microwave reactor, the microwave power was set to 100W and the frequency to 5525MHz. Other conditions and implementation steps were the same as in Example 1.
[0055] In this embodiment, the catalytic bed temperature is 518°C, and the composition and volume fraction of the gasification products at a frequency of 5525MHz are H2: 56.4%, CO: 42%, CO2: 1.6%, and NH3 concentration is 16.5ppm.
[0056] The effect of microwave frequency on ammonia synthesis is shown in Examples 1-7, and the results are as follows: Figure 2 As shown.
[0057] Biomass charcoal gasification is a strongly endothermic reaction; high temperatures favor increased gas yield and regulate gas distribution, such as the volume fraction of hydrogen and the hydrogen-to-CO ratio. Ammonia synthesis, being an exothermic reaction, reverses as temperature increases, hindering ammonia production. In the series system of frequency-converting microwave-induced biomass gasification and in-situ atmospheric pressure ammonia synthesis and hydrogen storage, the frequency selectively acts on two absorbing media, creating temperature differences and inducing different reactions. Examples 1-7 demonstrate that this series system can achieve this technology within a frequency range of 2450 MHz to 5525 MHz; the highest ammonia concentration, reaching 31.5 ppm, is achieved at a microwave frequency of 5400 MHz.
[0058] Example 8
[0059] In the microwave reactor, the microwave power was set to 100W, the frequency to 5525MHz, the N2 volume fraction to 30%, and the H2 and CO volume fractions to 50% and 20%, respectively. Other conditions and implementation steps are as follows.
[0060] The first step is to fill a quartz tube with an inner diameter of 8mm with quartz wool, and then fill the quartz tube with 2g of α-Fe and fix it with quartz wool.
[0061] The second step is to connect the quartz tube to the reaction system, check the airtightness, purge the reaction system with nitrogen and keep the reactor in an inert atmosphere.
[0062] The third step is to turn on the microwave power supply and input the frequency-converted microwave into the microwave resonant cavity through the microwave feed port. After the catalyst absorbs the microwave, it begins to heat up. The temperature change of the catalyst is detected in real time by an infrared thermometer and a thermal imager at the axial section of the quartz tube.
[0063] Step 4: After reaching and stabilizing the reaction temperature, adjust the nitrogen flow rate and adjust the flow meter to control the hydrogen and CO to be introduced into the reactor at predetermined flow rates;
[0064] Step 5: Collect gaseous products using a gas sampling bag and analyze them offline in a gas chromatograph.
[0065] The catalytic bed temperature was 490℃ and the NH3 concentration was 15.1ppm.
[0066] Example 9
[0067] In the microwave reactor, the microwave power was set to 100W, the frequency to 5525MHz, and the volume fractions of H2 and CO to be 60% and 20%, respectively. Other conditions and implementation steps were the same as in Example 8.
[0068] The catalytic bed temperature was 520℃ and the NH3 concentration was 15.6ppm.
[0069] Example 10
[0070] In the microwave reactor, the microwave power was set to 100W, the frequency to 5525MHz, and the volume fractions of H2 and CO to be 40% and 20%, respectively. Other conditions and implementation steps were the same as in Example 8.
[0071] The catalytic bed temperature was 524℃ and the NH3 concentration was 16.3ppm.
[0072] The effect of the hydrogen-to-carbon ratio on ammonia synthesis is shown in Examples 8-10, and the results are as follows: Figure 3 As shown.
[0073] The ratio of hydrogen to CO is one of the important influencing factors in the utilization of syngas from biomass gasification. In order to explore its feasibility in hydrogen storage technology for ammonia synthesis, hydrogen, CO and nitrogen were used as reactant gases to investigate the effect of the hydrogen-carbon ratio on hydrogen storage technology for ammonia synthesis. As shown in Examples 8-10, hydrogen storage for ammonia synthesis at atmospheric pressure can be achieved by frequency conversion microwave induction within the range of hydrogen to CO ratio of 40%:20% to 60:20%.
Claims
1. A method for producing green hydrogen from biomass and storing it in situ, characterized in that, Using biochar as a microwave absorber and reactant, water is gasified and then introduced into a microwave reactor. Water vapor passes from top to bottom through the char bed to produce syngas through a water-gas reaction. An α-Fe catalyst is connected in series in the lower layer of biochar. The resulting syngas reacts with N2 at atmospheric pressure to produce NH3 under α-Fe catalysis in a microwave reactor with adjustable microwave frequency.
2. The method for producing green hydrogen from biomass and storing it in situ according to claim 1, characterized in that, When biochar is used as a microwave absorber and reactant, the microwave frequency is 2450-5525MHz and the power is 100W.
3. The method for producing green hydrogen from biomass and storing it in situ according to claim 1, characterized in that, The volume fraction of H2 produced by biomass charcoal steam gasification is 52%-60.7%, and the volume fraction of CO is 22.8%-45.8%.
4. The method for producing green hydrogen from biomass and storing it in situ according to claim 1, characterized in that, Using α-Fe as the microwave absorber and catalyst, the microwave frequency was 2450-5525MHz, the power was 100W, and the space velocity was 1200-3600h. -1 The reaction temperature is 303-560℃.
5. The method for producing green hydrogen from biomass and storing hydrogen in situ according to any one of claims 1-4, characterized in that, Includes the following steps: The first step is to fill the quartz tube with quartz wool, and then fill the quartz tube with α-Fe and biochar in sequence, and fix them with quartz wool. The second step is to connect the quartz tube to the reaction system, check the airtightness, purge the reaction system with nitrogen and keep the reactor in an inert atmosphere. The third step is to turn on the microwave power supply and input the frequency-converted microwave into the microwave resonant cavity through the microwave feed port. After the absorbing material absorbs microwaves of different frequencies, it begins to heat up, and the temperature change of the catalyst is monitored in real time. Step 4: After reaching and stabilizing the reaction temperature, water is vaporized in a preheating furnace at a predetermined flow rate and then introduced into the reactor. Step 5: After the reaction is complete, collect the gaseous products.
6. The method for producing green hydrogen from biomass and storing it in situ according to claim 5, characterized in that, The water flow rate is 0.2 ml / min, and the vaporization temperature is 100-250℃.