Preparation and application method of a catalyst for CO2 reduction and O2 regeneration

Abstract

The application discloses a preparation and application method of a catalyst for CO2 reduction and O2 regeneration, and belongs to the field of catalysts.The catalyst is prepared by the following steps: dissolving V2O5 powder and oxalic acid in deionized water, adding the mixture into isopropyl alcohol, stirring, and then performing high-pressure high-temperature reaction, washing and drying to obtain VO2 nano powder; mixing the VO2 nano powder with CeO2 powder and In2O3 powder in a certain proportion, adding the mixture into a certain amount of anhydrous ethanol, stirring and dispersing, performing solid-liquid separation, washing and drying, and then calcining to obtain mixed powder; performing surface modification on the prepared mixed powder to obtain surface-modified mixed powder; and using HZSM-5 molecular sieve to prepare a molecular sieve network template, and loading the prepared surface-modified mixed powder on the molecular sieve network template to obtain the catalyst for CO2 reduction and O2 regeneration.The catalyst prepared by the application is applied to catalyze low-energy electron adhesion reduction of CO2 to generate O2, and the catalytic efficiency and O2 generation rate of the CO2 reduction to generate O2 are effectively improved, and the continuous reduction of CO2 and the continuous and rapid supply of O2 in a closed environment are ensured.

Description

Technical Field

[0001] This invention belongs to the field of radiochemistry and radiation chemistry technology. More specifically, this invention relates to a method for preparing and applying a catalyst for CO2 reduction and O2 regeneration. Background Technology

[0002] Military confined spaces are among the most common operational environments and combat platforms for troops. Due to human metabolism, the operation of power equipment, and the oxidation of some materials, O2 in military confined spaces is rapidly consumed, producing CO2. If the generated CO2 is not removed in time, it will reach a concentration that is harmful to the human body, thus becoming the main factor threatening the safety of soldiers and affecting the long-term operational capability of military confined spaces.

[0003] CO2 concentration control is a crucial component of military confined space environmental control and life support systems, requiring it to be maintained at low levels. Military confined space environments have stringent CO2 concentration control requirements. For example, in nuclear submarines, CO2 concentrations generally need to be controlled below 0.8%, while in spacecraft cabins and other confined spaces far from the ground, CO2 concentrations must be controlled below 0.6%, significantly lower than in ground-based systems. CO2 concentration directly affects the composition and efficiency of CO2 purification products using ionizing radiation technology. Higher CO2 concentrations are beneficial for precise control and improved purification efficiency of carbon-containing fuels. However, low CO2 levels in confined spaces severely impact the efficiency of CO2 reduction by ionizing radiation. Furthermore, the air composition in military confined spaces is complex and diverse. In addition to the main atmospheric components such as nitrogen, oxygen, and rare gases, the operation of equipment, the volatilization of non-metallic materials, and human metabolism all generate various harmful gases, such as H2, CO, CH4, volatile organic compounds (VOCs), and odorous gases. The presence of these substances reduces the efficiency of low-energy electron attachment reduction of CO2 and results in overly complex product composition after CO2 reduction by ionizing radiation, increasing the difficulty of subsequent product separation and utilization. Therefore, selectively capturing and enriching CO2 in a confined space before participating in the low-energy electron attachment reduction reaction is key to improving the efficiency of low-energy electron radiation in purifying CO2.

[0004] Currently, common catalysts used in the catalytic reduction of carbon dioxide include various metal oxides and molecular sieves. For example, Chinese invention patent application number 202220524746.2 discloses an in-situ resource utilization system for air regeneration, which uses iridium dioxide (IrO2) as a catalyst at the anode of the catalytic device to catalyze the reduction of carbon dioxide to oxygen and carbon monoxide. Molecular sieves are mostly used to catalyze the reduction of carbon dioxide to other olefinic organic compounds. For example, Chinese invention patent application number 202210613814.7 discloses a process for the hydrogenation of carbon dioxide to aromatics using a bifunctional catalyst, which uses SAPO-n molecular sieve and HZSM-5 molecular sieve as catalysts. In the process of low-energy electron attachment reduction of CO2, both metal oxides and molecular sieves can be selected as catalysts. However, the catalytic effect and catalytic rate of single molecular sieve and metal oxide catalysts for the low-energy electron attachment reduction to oxygen are not ideal. In order to improve the rate of carbon dioxide attachment reduction to oxygen in a confined space, it is necessary to improve the existing catalysts for carbon dioxide attachment reduction. Summary of the Invention

[0005] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0006] To achieve these objectives and other advantages according to the present invention, a method for preparing a catalyst for CO2 reduction and O2 regeneration is provided, comprising the following steps:

[0007] Step 1: Dissolve V2O5 powder and oxalic acid in deionized water, add to isopropanol and stir, then carry out high pressure and high temperature reaction. Wash and dry the black product to obtain VO2 nanopowder. Mix VO2 nanopowder with CeO2 powder and In2O3 powder in proportion, add to a certain amount of anhydrous ethanol, stir and disperse, separate solid and liquid, wash and dry, and calcine to obtain mixed powder.

[0008] Step 2: Surface-modify the prepared mixed powder to obtain surface-modified mixed powder;

[0009] Step 3: Prepare a molecular sieve mesh template using HZSM-5 molecular sieve, and load the prepared surface-modified mixed powder onto the molecular sieve mesh template to obtain a catalyst for CO2 reduction and O2 regeneration.

[0010] Preferably, in step one, the particle size of CeO2 powder is 5-100 nm, the particle size of In2O3 powder is 20-100 nm, and the particle size of V2O5 powder is 10-100 nm.

[0011] Preferably, in step one, the molar volume ratio of V2O5 powder, oxalic acid, deionized water, and isopropanol is 5-10 mmol: 15-25 mmol: 300-800 mL: 5-10 mL; and the mass-volume ratio of VO2 nanopowder, CeO2 powder, In2O3 powder, and anhydrous ethanol is 5-10 g: 1-3 g: 2-4 g: 100-250 mL.

[0012] Preferably, in step one, the high-temperature and high-pressure reaction specifically involves adding isopropanol to a mixed solution of V2O5 and oxalic acid, heating it to 60–90°C, maintaining the temperature for 2–4 hours, then transferring it to a high-pressure reactor, setting the pressure to 5–8 MPa, and raising the temperature to 250–350°C for 2–4 hours.

[0013] Preferably, in step one, the calcination temperature is 600–1000℃ and the calcination time is 5–12 hours.

[0014] Preferably, in step two, the specific method for surface modification of the prepared mixed powder includes:

[0015] S21. Prepare a base solution using ethylene glycol, tetraethyl orthosilicate, and sodium hydroxide solution. Add the mixed powder to the base solution, stir and heat, keep warm for a certain time, cool to room temperature, and let it stand and age for a period of time.

[0016] S22. The solid-liquid mixture is separated into powders, dried, and then heat-treated in a hydrogen atmosphere to obtain surface-modified powders.

[0017] Preferably, in step S21, the mass-to-volume ratio of the mixed powder, ethylene glycol, tetraethyl orthosilicate, and sodium hydroxide solution is 2-6 g: 5-10 mL: 1-3 mL: 1-5 mL, wherein the mass fraction of the sodium hydroxide solution is 20%-30%.

[0018] The stirring and heating temperature is 40-80℃, the holding time is 2-5 hours, and the standing and aging time is 12-24 hours.

[0019] Preferably, in step S22, the heat treatment temperature is 200–400°C and the heat treatment time is 20–60 min.

[0020] Preferably, the specific method of step three includes:

[0021] S31. The HZSM-5 molecular sieve is pulverized into 200-400 mesh powder. The HZSM-5 molecular sieve powder is added to ethanol, stirred evenly, and then allowed to stand. After evaporation and concentration into a paste, a certain amount of polyvinyl alcohol is added, stirred and mixed evenly, and the paste is coated on the surface of the grid template. The ethanol is removed by heating. The grid-shaped HZSM-5 molecular sieve is then removed from the grid template.

[0022] S32. Add the mixed powder to ethanol and stir to form a suspension. Immerse the grid-like HZSM-5 molecular sieve into the bottom of the suspension and heat to evaporate the ethanol. The catalyst for CO2 reduction and O2 regeneration is then prepared.

[0023] In S31, the mass-to-volume ratio of HZSM-5 molecular sieve powder, ethanol, and polyvinyl alcohol is 10-20g: 50-250mL: 1-4mL.

[0024] In S32, the mass-to-volume ratio of the mixed powder, ethanol, and HZSM-5 molecular sieve powder is 0.1–2 g: 10–20 g: 25–100 mL.

[0025] An application of a catalyst for CO2 reduction and O2 regeneration, which is used in an integrated system for CO2 purification and O2 regeneration to achieve low-energy electron attachment reduction of CO2 and regeneration of O2.

[0026] The present invention has at least the following beneficial effects:

[0027] The present invention provides a method for preparing a catalyst for CO2 reduction and O2 regeneration. This involves mixing and calcining metal oxide VO2 nanopowder, In2O3 powder, and CeO2 powder, followed by surface modification, and then loading the mixture onto an HZSM-5 molecular sieve mesh template. The HZSM-5 molecular sieve mesh template serves not only as a carrier for the metal oxide powders (VO2 nanopowder, In2O3 powder, CeO2 powder) but also as an important catalyst in the CO2 catalytic reduction process. Utilizing the large specific surface area of ​​the HZSM-5 molecular sieve mesh template and the superior catalytic reduction effect of the surface-modified metal oxide powders, the method achieves an organic combination of the two catalysts: metal oxide powder and HZSM-5 molecular sieve. This forms a composite catalyst structure of metal oxide powder and HZSM-5 molecular sieve, which synergistically and complementaryly completes the process of reducing CO2 to O2 through low-energy electron attachment, improving the catalytic reduction effect of CO2 through low-energy electron attachment and enhancing both CO2 catalytic reduction efficiency and O2 generation rate.

[0028] This invention modifies the surface of metal oxide powders (VO2 nanopowder, In2O3 powder, CeO2 powder) before loading them onto an HZSM-5 molecular sieve template. Hydroxyl defects are introduced onto the surface of these powders, creating a unique hydrogen-bonded microenvironment that effectively captures weakly bound electrons and stabilizes the adsorption of CO2 reaction intermediates. During the low-energy electron-attachment reduction of CO2, CO2 and water vapor are first pre-adsorbed onto the surface of the metal oxide powders (VO2 nanopowder, In2O3 powder, CeO2 powder), followed by the capture of weakly bound electrons and surface free radical reactions. Finally, surface free radical intermediates capture electrons to form negative ion fragments, which desorb and form carbon-containing products. The surface of the medium catalytic material contains electron-rich trapping centers, which can promote the capture of weakly bound electrons, reduce the energy barrier required for CO2 reduction, selectively regulate CO2 reduction products, and improve CO2 reduction efficiency and O2 generation rate.

[0029] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of an integrated system for purifying CO2 and regenerating O2 using low-energy electron radiation in a confined space.

[0031] Figure 2 A schematic diagram of the low-energy electron source and beam monitoring module;

[0032] Figure 3 This is a TEM image of the VO2 nanopowder prepared in step one of Example 1;

[0033] Figure 4 This is a TEM image of the VO2 nanopowder prepared in step one of Example 2;

[0034] Figure 5 This is a TEM image of the VO2 nanopowder prepared in step one of Example 3;

[0035] Figure 6 Thermogravimetric (TG) curve of the VO2 nanopowder prepared in step one of Example 1;

[0036] Figure 7 The image shows the XRD pattern of the VO2 nanopowder prepared in step one of Example 1. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0038] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0039] Example 1

[0040] This embodiment provides a method for preparing a catalyst for CO2 reduction and O2 regeneration, including the following steps:

[0041] Step 1: Dissolve 6 mmol of V₂O₅ powder with a particle size distribution of 10–100 nm and 18 mmol of oxalic acid in 50 mL of deionized water. Add 600 mL of isopropanol and stir. Heat to 80 °C and maintain this temperature for 2 hours. Then transfer the mixture to a high-pressure reactor, set the pressure to 6 MPa, and raise the temperature to 250 °C. React for 4 hours. Wash and dry the black product to obtain VO₂ nanoparticles. TEM image of VO₂ nanoparticles is shown below. Figure 3 As shown, the thermogravimetric (TG) curve of VO2 nanoparticles is as follows. Figure 6 As shown, the XRD pattern of VO2 nanopowder is as follows. Figure 7 As shown;

[0042] 50g of VO2 nanopowder was mixed with 10g of CeO2 powder with a particle size of 5-100nm and 20g of In2O3 powder with a particle size of 20-100nm. The mixture was added to 1000mL of anhydrous ethanol, stirred and dispersed, separated into solid and liquid, washed and dried, and calcined at 600℃ for 6h to obtain the mixed powder.

[0043] Step 2: Surface modification of the prepared mixed powder, specifically including:

[0044] S21. Prepare a base solution using 50 mL of ethylene glycol, 10 mL of tetraethyl orthosilicate, and 10 mL of 20% sodium hydroxide solution. Add 40 g of mixed powder to the base solution, stir and heat to 60°C, keep warm for 2 hours, cool to room temperature, and let stand for 12 hours to age.

[0045] S22. The solid-liquid mixture is separated into powders, dried, and then heat-treated in a hydrogen atmosphere at a temperature of 300℃ for 40 minutes to obtain surface-modified powders.

[0046] Step 3: Prepare a molecular sieve mesh template using HZSM-5 molecular sieve, and load the prepared surface-modified mixed powder onto the molecular sieve mesh template. Specific methods include:

[0047] S31. Crush 100g of HZSM-5 molecular sieve into powder of 200-400 mesh. Add the HZSM-5 molecular sieve powder to 500mL of ethanol, stir evenly and let stand. After evaporation and concentration into a paste, add 10mL of polyvinyl alcohol, stir and mix evenly, coat the paste onto the surface of the grid template, and heat to remove the ethanol. Remove from the grid template to obtain a grid-shaped HZSM-5 molecular sieve.

[0048] S32. Add 10g of mixed powder to 250mL of ethanol and stir to form a suspension. Immerse the grid-like HZSM-5 molecular sieve into the bottom of the suspension and heat to evaporate the ethanol. The catalyst for CO2 reduction and O2 regeneration is then prepared.

[0049] Example 2

[0050] This embodiment provides a method for preparing a catalyst for CO2 reduction and O2 regeneration, including the following steps:

[0051] Step 1: Dissolve 8 mmol of V₂O₅ powder with a particle size distribution of 10–100 nm and 20 mmol of oxalic acid in 60 mL of deionized water. Add the solution dropwise to 600 mL of isopropanol and stir. Heat to 80 °C and maintain this temperature for 3 hours. Then transfer the solution to a high-pressure reactor, set the pressure to 6 MPa, and raise the temperature to 300 °C. React for 3 hours. Wash and dry the black product to obtain VO₂ nanoparticles. TEM image of the VO₂ nanoparticles is shown below. Figure 4 As shown;

[0052] 80g of VO2 nanopowder was mixed with 20g of CeO2 powder with a particle size of 5-100nm and 30g of In2O3 powder with a particle size of 20-100nm. The mixture was added to 100-250mL of anhydrous ethanol, stirred and dispersed, separated into solid and liquid, washed and dried, and calcined at 600-1000℃ for 5-12h to obtain the mixed powder.

[0053] Step 2: Surface modification of the prepared mixed powder, specifically including:

[0054] S21. Prepare a base solution using 80 mL of ethylene glycol, 20 mL of tetraethyl orthosilicate, and 40 mL of 20% sodium hydroxide solution. Add 50 g of mixed powder to the base solution, stir and heat to 60°C, keep warm for 3 hours, cool to room temperature, and let stand for 12 hours to age.

[0055] S22. The solid-liquid mixture is separated into powders, dried, and then heat-treated in a hydrogen atmosphere at a temperature of 300℃ for 50 minutes to obtain surface-modified powders.

[0056] Step 3: Prepare a molecular sieve mesh template using HZSM-5 molecular sieve, and load the prepared surface-modified mixed powder onto the molecular sieve mesh template. Specific methods include:

[0057] S31. Crush 150g of HZSM-5 molecular sieve into 200-400 mesh powder. Add the HZSM-5 molecular sieve powder to 500mL of ethanol, stir evenly, and let stand. After evaporation and concentration into a paste, add 20mL of polyvinyl alcohol, stir and mix evenly, coat the paste onto the surface of a grid template, and heat to remove the ethanol. Remove the grid template to obtain a grid-shaped HZSM-5 molecular sieve.

[0058] S32. Add 15g of mixed powder to 250mL of ethanol and stir to form a suspension. Immerse the grid-like HZSM-5 molecular sieve into the bottom of the suspension and heat to evaporate all the ethanol. The catalyst for CO2 reduction and O2 regeneration is then prepared.

[0059] Example 3

[0060] This embodiment provides a method for preparing a catalyst for CO2 reduction and O2 regeneration, including the following steps:

[0061] Step 1: Dissolve 10 mmol of V₂O₅ powder with a particle size distribution of 10–100 nm and 25 mmol of oxalic acid in 80 mL of deionized water. Add the solution dropwise to 800 mL of isopropanol and stir. Heat to 90 °C and maintain this temperature for 4 hours. Then transfer the solution to a high-pressure reactor, set the pressure to 8 MPa, and raise the temperature to 350 °C. React for 2 hours. Wash and dry the black product to obtain VO₂ nanoparticles. TEM image of the VO₂ nanoparticles is shown below. Figure 5 As shown;

[0062] 100g of VO2 nanopowder was mixed with 30g of CeO2 powder with a particle size of 5-100nm and 40g of In2O3 powder with a particle size of 20-100nm in a certain proportion. The mixture was added to 1200mL of anhydrous ethanol, stirred and dispersed, separated into solid and liquid, washed and dried, and calcined at 1000℃ for 8h to obtain the mixed powder.

[0063] Step 2: Surface modification of the prepared mixed powder, specifically including:

[0064] S21. Prepare a base solution using 100 mL of ethylene glycol, 30 mL of tetraethyl orthosilicate, and 50 mL of 20% sodium hydroxide solution. Add 60 g of the mixed powder to the base solution, stir and heat to 40–80 °C, keep warm for 2–5 h, cool to room temperature, and let stand for 12–24 h.

[0065] S22. The solid-liquid mixture is separated into powders, dried, and then heat-treated in a hydrogen atmosphere at a temperature of 400℃ for 60 minutes to obtain surface-modified powders.

[0066] Step 3: Prepare a molecular sieve mesh template using HZSM-5 molecular sieve, and load the prepared surface-modified mixed powder onto the molecular sieve mesh template. Specific methods include:

[0067] S31. Crush 200g of HZSM-5 molecular sieve into powder of 200-400 mesh. Add the HZSM-5 molecular sieve powder to 1500mL of ethanol, stir evenly, and let stand. After evaporation and concentration into a paste, add 40mL of polyvinyl alcohol, stir and mix evenly, coat the paste onto the surface of a grid template, and heat to remove the ethanol. Remove the grid template to obtain a grid-shaped HZSM-5 molecular sieve.

[0068] S32. Add 20g of mixed powder to 1000mL of ethanol and stir to form a suspension. Immerse the grid-like HZSM-5 molecular sieve into the bottom of the suspension and heat to evaporate the ethanol. The catalyst for CO2 reduction and O2 regeneration is then prepared.

[0069] Comparative Example 1

[0070] This comparative example provides a method for preparing a catalyst for CO2 reduction and O2 regeneration. Compared with Example 1, the method omits the second step of surface modification of the mixed powder. Instead, 10g of the mixed powder is loaded onto 100g of HZSM-5 molecular sieve mesh template, and the remaining processes are the same as in Example 1.

[0071] Comparative Example 2

[0072] This comparative example provides a method for preparing a catalyst for CO2 reduction and O2 regeneration. Compared with the other examples in Example 1, 10g of VO2 nanopowder was surface modified and loaded onto 100g of molecular sieve mesh template. CeO2 powder and In2O3 powder were not added. The rest of the process was the same as in Example 1.

[0073] Comparative Example 3

[0074] This comparative example provides a method for preparing a catalyst for CO2 reduction and O2 regeneration. Compared with the other examples in Example 1, 10g of CeO2 nanoparticles were surface-modified and loaded onto 100g of molecular sieve mesh template. No VO2 powder or In2O3 powder was added. The rest of the process was the same as in Example 1.

[0075] Comparative Example 4

[0076] This comparative example provides a method for preparing a catalyst for CO2 reduction and O2 regeneration. Compared with the other examples in Example 1, 10g of In2O3 nanoparticles were surface-modified and loaded onto 100g of molecular sieve mesh template. No VO2 powder or CeO2 powder was added. The rest of the process was the same as in Example 1.

[0077] Comparative Example 5

[0078] This comparative example provides a method for preparing a catalyst for CO2 reduction and O2 regeneration. Compared with the other examples in Example 1, this comparative example uses HZSM-5 molecular sieve as raw material and prepares HZSM-5 molecular sieve into a molecular sieve mesh template according to the method in step three of Example 1, without loading with metal oxides.

[0079] The catalysts prepared in Examples 1-3 and Comparative Examples 1-5 for CO2 reduction and O2 regeneration were applied to... Figures 1-2 The integrated system for purifying CO2 and regenerating O2 in a confined space using low-energy electron radiation, as shown, includes:

[0080] The CO2 reduction reaction chamber 1 has a reaction chamber 2 inside, and a stage 3 for placing the catalyst is provided in the reaction chamber 2. The CO2 reduction reaction chamber 1 is provided with an electron gun interface 4.

[0081] A low-energy electron source 5 is connected to the CO2 reduction reaction chamber 1 via an electron gun interface 4, and the electron beam extraction port 51 of the low-energy electron source 5 corresponds to the stage 3.

[0082] The CO2 enrichment device 6 is connected to a circulation pump (not shown). The CO2 enrichment device 6 is equipped with a CO2 capture module and a heating module connected to the CO2 capture module. The CO2 enrichment device 6 is connected to the CO2 reduction reaction chamber 1 through a pipeline.

[0083] A steam generator 7 is connected to the CO2 reduction reaction chamber 1 via a pipe.

[0084] Working Principle: This invention provides an integrated system for purifying CO2 and regenerating O2 in a confined space using low-energy electron radiation. First, the CO2 capture module in the CO2 enrichment device 6 selectively adsorbs CO2 from the air pumped in by the circulating pump (the air in a confined space has a complex and diverse composition, mainly composed of nitrogen, oxygen, rare gases, CO2, and other gases). Once the CO2 capture module reaches saturation, it desorbs CO2 by heating the module. The desorbed CO2 is then transported to the reaction chamber 2 through a pipeline. After the CO2 in the reaction chamber 2 reaches a certain amount, the steam generator 7 supplies a certain amount of water to the reaction chamber 2. Then, the low-energy electron source 5 generates a low-energy electron beam, which is guided to the catalyst surface in the reaction chamber 2. The low-energy electrons adhere to and reduce CO2 / H2O to generate O2 and carbon-based fuel, thus achieving CO2 removal and O2 regeneration. The catalysts prepared in Examples 1-3 and Comparative Examples 1-5 for CO2 reduction and O2 regeneration were placed on stage 3 for catalytic CO2 reduction and O2 regeneration. Adding a medium catalyst material that captures CO2 / H2O, provides weakly bound electrons, and lowers the energy barrier for CO2 reaction intermediate formation within the reaction chamber can effectively regulate the low-energy electron-attached CO2 reduction activity and the selectivity of carbon-containing products. The catalysts prepared in Examples 1-3 and Comparative Examples 2-5, which introduce hydroxyl defects on the surface of metal oxides, are ideal choices for medium materials. They can form a special hydrogen-bonded microenvironment on the surface, achieving effective capture of weakly bound electrons and stabilization of CO2 reaction intermediate adsorption. In the low-energy electron-attached CO2 reduction process, CO2 and water vapor are first pre-adsorbed on the catalyst material surface, followed by the capture of weakly bound electrons and surface free radical reactions. Finally, surface free radical intermediates capture electrons to form negative ion fragments, which desorb and form carbon-containing products. The surface of the medium catalytic material contains electron-rich trapping centers, which can promote the capture of weakly bound electrons, reduce the energy barrier required for CO2 reduction, selectively regulate CO2 reduction products, and improve CO2 reduction efficiency.

[0085] Low-energy electrons attach to CO2 molecules to form transient negative ion molecules (CO2) in an electron-molecule resonance state. 2- The CO2 gas then decays and dissociates into neutral O2 molecules and negatively charged carbanion fragments. This process not only reduces CO2 back to O2, but the generated carbanions can also participate in subsequent chemical reactions to produce specific carbon-containing products such as hydrocarbons, alcohols, and carboxylic acids. When using a low-energy electron source to generate low-energy electrons to attach and dissociate moistened CO2 gas, O2 and small amounts of hydrocarbons and alcohols were detected in the products, which are believed to be caused by the reaction of carbanions and H2O. In addition, because the energy of the attached electrons matches the C=O bond energy in CO2 (8.4 eV, 803 kJ / mol), selective regulation of specific products such as hydrocarbons, alcohols, and carboxylic acids can be achieved.

[0086] By controlling the voltage, power, and focusing magnetic field strength of the low-energy electron source 5, parameters such as the energy, energy dissipation, and flux intensity of the low-energy electron beam can be adjusted, enabling precise control of O2 production and carbon-containing fuels. During the ionizing radiation reduction of CO2, CO2 can not only be reduced and regenerated into O2, but the generated carbon anion fragments can also participate in subsequent chemical reactions to produce fuel products such as hydrocarbons, alcohols, and carboxylic acids. This invention is applicable to various military confined space applications, improving the long-term operational capability and wartime survivability in military confined spaces.

[0087] The structure of the low-energy electron source 5 includes:

[0088] The gun body 52 has a cathode 53 and an anode 54 opposite to the cathode 53 inside.

[0089] A gate 55 is disposed at the rear end of the anode 54;

[0090] A guiding and focusing module is disposed at the rear end of the gate 55, the guiding and focusing module comprising:

[0091] The guide tube 56 has its central axis coincident with the central axis of the anode 54, cathode 53, and gate 55, and the guide tube 56 is connected to the electron beam extraction port 51;

[0092] Multiple Helmholtz coils 57 are disposed outside the guide tube 56.

[0093] The cathode 53 emits electrons, the grid 55 controls the actual emission area of ​​the cathode 53 and pre-focuses the electron beam, and the anode 54 accelerates the electrons. The cathode 53 is set to a negative high voltage, and the anode 54 is grounded to create a potential difference. The thermionic electrons emitted by the cathode 53 are accelerated to form a low-energy electron beam. The grid 55 controls the focusing of the low-energy electron beam and the number of emitted electrons. The cathode 53 of the low-energy electron source 5, heated and excited to generate a large number of low-energy electrons, is the core component of the low-energy electron beam control system. The choice of material for the cathode 53 plays a decisive role in the emission capability and lifetime of the low-energy electron source. The cathode 53 needs to be made of a material with a high melting point and high resistivity. After passing a strong current, the cathode 53 is heated to over 1000℃. Furthermore, a material with low work function needs to be selected. When the outer electrons of the atoms on the surface of the cathode 53 are excited by a certain amount of thermal energy, they will break free from the atomic nucleus and become free electrons.

[0094] Low-energy electrons, influenced by the Earth's magnetic field and spatial dispersion field, will exhibit a space charge effect, thus increasing the energy divergence of the low-energy electron beam. To overcome the electron beam dispersion caused by the space charge effect, a guiding and focusing magnetic field is needed to constrain the trajectory of the low-energy electrons. The main component of the guiding and focusing module is a Helmholtz coil 57, composed of parallel coils in an enameled aluminum tube with an outer diameter of 1.6 cm. After the electron beam emitted by the low-energy electron source 5 enters the guiding tube 56, it is guided and controlled by the magnetic field region generated by the Helmholtz coil 57 to form a controllable electron beam current. The energy divergence of the electron beam current can be controlled by adjusting the applied voltage and current at the center of the two coils.

[0095] In the above technical solution, the cathode 53 is one of tantalum sheet, tungsten wire, and lanthanum hexaboride electrode sheet. They have the advantages of reliable performance and long life. Taking into account factors such as the working environment, working voltage, beam spot diameter and beam current of the low-energy electron source 5, tantalum sheet with thermal emission excitation method is selected as the cathode.

[0096] A beam monitoring module is also provided at the end of the low-energy electron source 5. The beam monitoring module is located between the guide tube 56 and the electron beam exit port 51. The beam monitoring module is a Faraday tube and includes:

[0097] The first electrode plate 58 is located near the guide tube. The rear end of the first electrode plate 58 is provided with a second electrode plate 59 and a third electrode plate 510. The third electrode plate 510 is integrally connected to a triangular tube 511.

[0098] The first electrode plate 58 and the second electrode plate 59 form a deceleration analysis field, and the third electrode plate 510 is welded to the triangular tube 511 to receive electrons and prevent electron bounce. By scanning the voltage of the second electrode plate 59 (scanning from 0V to negative voltage), the electron beam current reaching the third electrode plate 510 is gradually reduced to 0. The magnitude of the electron beam current at the Faraday tube collector is directly measured, and then the energy of the electron beam current is calculated by differentiating the electron beam current received by the third electrode plate 510 and the scanning voltage.

[0099] The CO2 capture module and the heating module are configured such that the heating module is an electric heating plate 61, and the CO2 capture module is a porous CO2 adsorbent capture net 62 disposed on the electric heating plate 61.

[0100] The porous CO2 adsorbent capture net 62 is made of one of the following materials: biochar, silica gel, zirconium sodium zeolite, metal-organic frameworks (MOFs), metal-organic frameworks (ZIF-C), AL2O3, CeO2, and La2O3. These materials can selectively adsorb CO2 in mixed air.

[0101] When the CO2 adsorbent capture net 62 adsorbs CO2 to saturation, the electric heating plate 61 heats it to desorb CO2 from the CO2 adsorbent capture net 62, and finally enters the reaction chamber 2 through the pipeline.

[0102] The CO2 reduction reaction chamber 1 is equipped with a radiation shielding layer 8. The material of the shielding layer 8 is lead. The radiation shielding layer 8 is used to shield low-energy electrons and negative ion fragments, and to block or weaken the low-energy electrons and negative ion fragments emitted by the electron source.

[0103] The CO2 reduction reaction chamber 1 is also equipped with a thermometer and a pressure gauge, as well as a vacuum port 9 on the opposite side of the CO2 and H2O inlet ports. The vacuum port 9 is used for evacuating the CO2 before it enters the reaction chamber.

[0104] Meanwhile, the integrated system for purifying CO2 and regenerating O2 in a confined space using low-energy electron radiation is also equipped with a negative ion detection system, which includes:

[0105] An inhalation gas sampler, which is connected to the reaction chamber;

[0106] The sensor is connected to the reaction chamber;

[0107] The data processing and control module communicates with the inhaled gas sampler and sensors. This module monitors the concentration of carbanion ions in the reaction chamber in real time via sensors, optimizes low-energy electron settings, and adjusts the CO2 reduction reaction path to obtain specific carbon-based fuel products, thereby improving the selectivity of specific carbon-containing fuels. The inhaled gas sampler samples the reduction gas products in the reaction chamber, and online detection instruments such as gas chromatography and liquid chromatography are used to analyze and detect the CO2 reduction reaction products. The inhaled gas sampler, sensors, and data processing and control module are all commercially available products.

[0108] The integrated system for purifying CO2 and regenerating O2 in a confined space using low-energy electron radiation also includes a product collection and detection system, comprising:

[0109] The product separation chamber 10 is connected to the reaction chamber 2 via a pipeline, and the product separation chamber 10 is also equipped with an online product detector;

[0110] Gas storage tank 11 is connected to product separation chamber 10;

[0111] The liquid storage tank 12 is connected to the product separation chamber 10;

[0112] Low-energy electron attachment reduces CO2 / H2O to generate various reduction products, which need to be separated, collected, and reused. Therefore, a product collection and monitoring system is designed, consisting of a product separation chamber 10, a gas storage tank 11, a liquid storage tank 12, and an online product detector (all commercially available products). O2 separated in the product separation chamber 10 is directly discharged to participate in the internal gas circulation. The remaining gaseous products are transferred to the gas storage tank 11 for storage, and the liquid storage tank 12 stores liquid carbon-based fuel. The product separation chamber 10 can utilize molecular sieves that selectively adsorb CO2 from the products; or existing mature membrane separation technologies, including pressure-driven and permeation-driven membranes. The online product detector monitors the composition and concentration changes of the CO2 reduction products in real time, providing timely warnings in case of abnormalities to prevent safety accidents.

[0113] 10g of the catalysts prepared in Examples 1-3 and Comparative Examples 1-5 for CO2 reduction and O2 regeneration were weighed and placed on stage 3. The product separation chamber 10 was removed, and catalytic CO2 reduction and O2 regeneration were performed. The CO2 enrichment device 6 was set to allow CO2 to enter reaction chamber 2 at a flow rate of 800 sccm, and the reaction time was 4 h. The O2 concentration in the reaction chamber before and after the reaction was measured by gas chromatography. The CO2 conversion rate, O2 selectivity, and O2 generation rate were calculated. The formula for calculating the CO2 conversion rate is as follows:

[0114]

[0115] in, The CO2 concentration in the reaction chamber before the reaction. This represents the CO2 concentration in the reaction chamber after the reaction.

[0116] The formula for calculating the O2 selectivity rate is as follows:

[0117]

[0118] in, This refers to the O2 concentration inside the reaction chamber.

[0119] The formula for calculating the O2 generation rate is:

[0120]

[0121] The following table was obtained:

[0122]

[0123]

[0124] As can be seen from the table above, compared with the catalysts prepared in Comparative Examples 1-5, the materials prepared in Examples 1-3, when used as catalysts for the low-energy electron attachment reduction of CO2 to O2, exhibit higher CO2 conversion, O2 selectivity, and O2 generation rate. This indicates that the catalyst prepared using the method disclosed in this invention for preparing catalysts for CO2 reduction and O2 regeneration improves the CO2 conversion, O2 selectivity, and O2 generation rate for the low-energy electron attachment reduction of CO2 to O2.

[0125] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0126] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a catalyst for CO2 reduction and O2 regeneration, characterized in that, Includes the following steps: Step 1: Dissolve V2O5 powder and oxalic acid in deionized water, add to isopropanol and stir, then carry out high pressure and high temperature reaction. Wash and dry the black product to obtain VO2 nanopowder. Mix VO2 nanopowder with CeO2 powder and In2O3 powder in proportion, add to a certain amount of anhydrous ethanol, stir and disperse, separate solid and liquid, wash and dry, and calcine to obtain mixed powder. Step 2: Surface-modify the prepared mixed powder to obtain surface-modified mixed powder; Step 3: Prepare a molecular sieve mesh template using HZSM-5 molecular sieve, and load the prepared surface-modified mixed powder onto the molecular sieve mesh template to obtain a catalyst for CO2 reduction and O2 regeneration; In step two, the specific method for surface modification of the prepared mixed powder includes: S21. Prepare a base solution using ethylene glycol, tetraethyl orthosilicate, and sodium hydroxide solution. Add the mixed powder to the base solution, stir and heat, keep warm for a certain time, cool to room temperature, and let it stand and age for a period of time. S22. The solid-liquid mixture is separated into powders, dried, and then heat-treated in a hydrogen atmosphere to obtain surface-modified powders.

2. The method for preparing the catalyst for CO2 reduction and O2 regeneration as described in claim 1, characterized in that, In step one, the particle size of CeO2 powder is 5~100 nm, the particle size of In2O3 powder is 20~100 nm, and the particle size of V2O5 powder is 10~100 nm.

3. The method for preparing the catalyst for CO2 reduction and O2 regeneration as described in claim 1, characterized in that, In step one, the molar volume ratio of V2O5 powder, oxalic acid, deionized water, and isopropanol is 5~10 mmol:15~25 mmol:30~80mL:300~800mL; the mass-volume ratio of VO2 nanopowder, CeO2 powder, In2O3 powder, and anhydrous ethanol is 5~10 g:1~3g:2~4 g:100~250mL.

4. The method for preparing the catalyst for CO2 reduction and O2 regeneration as described in claim 1, characterized in that, In step one, the high-temperature and high-pressure reaction specifically involves adding isopropanol to a mixed solution of V2O5 and oxalic acid, heating it to 60-90°C, maintaining the temperature for 2-4 hours, and then transferring it to a high-pressure reactor. The pressure is set to 5-8 MPa, and the temperature is raised to 250-350°C for 2-4 hours.

5. The method for preparing the catalyst for CO2 reduction and O2 regeneration as described in claim 1, characterized in that, In step one, the calcination temperature is 600~1000 ℃ and the calcination time is 5~12 h.

6. The method for preparing the catalyst for CO2 reduction and O2 regeneration as described in claim 1, characterized in that, In step S21, the mass-to-volume ratio of the mixed powder, ethylene glycol, tetraethyl orthosilicate, and sodium hydroxide solution is 2-6 g: 5-10 mL: 1-3 mL: 1-5 mL, wherein the mass fraction of the sodium hydroxide solution is 20%-30%. The stirring and heating temperature is 40~80 ℃, the holding time is 2~5 h, and the standing and aging time is 12~24 h.

7. The method for preparing the catalyst for CO2 reduction and O2 regeneration as described in claim 1, characterized in that, In step S22, the heat treatment temperature is 200~400 ℃ and the heat treatment time is 20~60 min.

8. The method for preparing the catalyst for CO2 reduction and O2 regeneration as described in claim 1, characterized in that, The specific methods for step three include: S31. The HZSM-5 molecular sieve is pulverized into 200-400 mesh powder. The HZSM-5 molecular sieve powder is added to ethanol, stirred evenly, and then allowed to stand. After evaporation and concentration into a paste, a certain amount of polyvinyl alcohol is added, stirred and mixed evenly, and the paste is coated on the surface of the grid template. The ethanol is removed by heating. The grid-shaped HZSM-5 molecular sieve is obtained by removing it from the grid template. S32. Add the mixed powder to ethanol and stir to form a suspension. Immerse the grid-like HZSM-5 molecular sieve into the bottom of the suspension and heat to evaporate the ethanol. The catalyst for CO2 reduction and O2 regeneration is then prepared. In S31, the mass-to-volume ratio of HZSM-5 molecular sieve powder, ethanol, and polyvinyl alcohol is 10-20 g: 50-250 mL: 1-4 mL. In S32, the mass-to-volume ratio of the mixed powder, ethanol, and HZSM-5 molecular sieve powder is 0.1~2 g:10~20 g:25~100 mL.

9. The application of a catalyst for CO2 reduction and O2 regeneration, wherein the catalyst for CO2 reduction and O2 regeneration is prepared by the method for preparing the catalyst for CO2 reduction and O2 regeneration according to any one of claims 1-8, characterized in that, The catalyst used for CO2 reduction and O2 regeneration is applied in an integrated system for CO2 purification and O2 regeneration to achieve low-energy electron attachment reduction of CO2 and regeneration of O2.

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