A method for preparing a high surface area thermoelectric catalytic material for CO2 waste gas treatment

Abstract

This invention discloses a method for preparing a high-surface-area thermoelectric catalytic material for CO2 waste gas treatment. The method includes: 1. ball milling raw material powder to obtain a mixed powder; 2. sintering the mixed powder with a flux to obtain a blocky BiCuSeO base material; 3. ball milling the blocky BiCuSeO base material with multi-scale polystyrene powder and then cold pressing it into shape; 4. solid-state sintering to obtain a high-surface-area BiCuSeO thermoelectric catalytic material. This invention uses a flux method combined with a multi-scale pore-forming agent to prepare a BiCuSeO thermoelectric catalytic material with a multi-level porous structure and high purity, improving the surface area and activity of the BiCuSeO thermoelectric catalytic material, achieving an extremely high CO2 waste gas conversion rate, suitable for CO2 waste gas treatment, and with a short preparation process, it has the outstanding advantages of low cost and no pollution, making it suitable for engineering applications.

Description

Technical Field

[0001] This invention belongs to the fields of powder metallurgy and thermoelectric catalysis, specifically relating to a method for preparing a high surface area thermoelectric catalytic material for CO2 waste gas treatment. Background Technology

[0002] With the increasing energy demands of high-energy-consuming industries such as smelting, thermal power, and automobiles, the emissions of waste heat and CO2 have also increased, leading to environmental pollution and higher environmental remediation costs. Therefore, it is necessary to find new energy conversion technologies, among which environmentally friendly and efficient catalysts are key to the post-treatment of waste heat and CO2. Currently, research is using thermoelectric materials as catalyst carriers and promoters for high-efficiency thermoelectric catalysis. This converts the temperature gradient distributed on the thermoelectric material into a potential difference, activating the chemical reaction at a lower temperature, accelerating the reaction rate, and even altering the selectivity of the reaction products. Therefore, the development of low-cost Ca3Co4O9-based thermoelectric catalytic materials has significant advantages in CO2 conversion efficiency.

[0003] Currently, there is no research in China on the application of thermoelectric catalysis in energy conversion, but there have been reports abroad.

[0004] Document "A. Achour, Tuning of catalytic activity by thermoelectric materials for carbon dioxide hydrogenation, Advanced Energy Materials 8 (2018)

[0005] Literature 701430 discloses the thermoelectric catalytic effect of the thermoelectric material BiCuSeO on the CO2 reduction reaction, finding that the thermoelectric effect can not only increase the reaction rate but also change the chemical equilibrium and affect product selectivity, ultimately achieving the conversion of CO2 to CO + H2O with high CO selectivity. However, the BiCuSeO thermoelectric catalytic material prepared in this literature is a bulk material, with a small effective contact area with CO2 waste gas, which greatly limits the catalytic reaction efficiency.

[0006] The patent "Z.Huang.Tuning of catalytic activity by thermoelectric materials:GB2017 / 053361[P].WO2018087540A1" discloses a technique for sputtering a thin film of noble metal Pt catalyst on the surface of a bulk thermoelectric material BiCuSeO. The prepared composite catalyst material is used to catalyze the oxidation reaction of C2H4, significantly improving the catalytic performance of the Pt catalyst and greatly increasing the reaction rate through the thermoelectric effect. However, this composite catalyst material contains expensive noble metals and does not involve research on CO2 waste gas catalysis.

[0007] Document "L.Yu-Jiung, Thermocatalytic hydrogen peroxide generation and environmental disinfection by Bi2Te3 nanoplates, Nature Communications

[0008] A method for preparing hydrogen peroxide for environmental disinfection using the thermoelectric material Bi2Te3 at a low temperature difference is disclosed in paper 12.1(2021)180. Another method for synthesizing hydrogen peroxide is disclosed in paper "Y. Jaeho, Heat-fueled enzymatic cascade for selective oxyfunctionalization of hydrocarbons, Nature Communications 13.1(2022)3741", which converts low-temperature waste heat into chemical energy using the thermoelectric material Bi2Te3. However, in both of these papers, the Bi2Te3 material is coated on the surface of a dissimilar matrix material in powder or particle form, resulting in limited effective contact area with the hot waste gas. This leads to poor overall thermoelectric performance of the resulting composite material, and neither paper addresses the application of this material in CO2 waste gas treatment. In general, the field of thermoelectric catalysis is still in its early stages of development, but it is foreseeable that thermoelectric materials, as catalysts, have greater application potential in energy conversion, chemical synthesis, and environmental remediation.

[0009] Given that catalytic reaction efficiency is closely related to the total contact area, it is necessary to scientifically increase the porosity of thermoelectric materials to increase the contact area in order to further improve the thermoelectric catalytic effect and increase the conversion rate of waste heat and CO2. This places new demands on the porosity and porous structure design of thermoelectric catalytic materials. However, current research on BiCuSeO thermoelectric catalytic materials focuses on bulk materials and cannot provide a reference. Therefore, it is necessary to propose a low-cost method for preparing high-surface-area BiCuSeO thermoelectric catalytic materials for engineering applications. Summary of the Invention

[0010] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a method for preparing a high-surface-area thermoelectric catalytic material for CO2 waste gas treatment. This method employs a process combining fluxing and solid-state sintering to prepare a BiCuSeO thermoelectric catalytic material with high purity, no impurities, and a hierarchical porous structure. This increases the surface area of ​​the BiCuSeO thermoelectric catalytic material, thereby enhancing its catalytic activity and achieving extremely high CO2 waste gas conversion rates, thus solving the problems of low surface area and low catalytic activity in thermoelectric catalytic materials.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing a high surface area thermoelectric catalytic material for CO2 waste gas treatment, characterized in that the method includes the following steps:

[0012] Step 1: Raw material mixing: Based on the atomic percentage of each element in BiCuSeO, Bi2O3 powder, Bi powder, Cu powder, and Se powder with a mass purity greater than 99% are used as raw materials. The raw materials are weighed in a mass ratio of 2.33:1.17:1:1.18. The weighed raw material powder is poured into an agate ball mill jar and agate grinding balls are added. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling to obtain mixed powder.

[0013] Step 2: Preparation of BiCuSeO base material by flux method: Using B2O3 powder as flux, the mixed powder obtained in step 1 is sintered, and the resulting blocky BiCuSeO base material is obtained.

[0014] Step 3, Pore Formation and Cold Pressing: The blocky BiCuSeO base material obtained in Step 2 is placed in an agate ball mill jar, multi-scale polystyrene powder is added as a pore-forming agent and agate grinding balls are placed in it. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling to obtain preform powder. The preform powder is then filled into a mold for cold pressing to obtain the BiCuSeO preform.

[0015] Step 4: Solid-state sintering: The BiCuSeO preform obtained in step 3 is placed in a tube furnace and solid-state sintering is performed under the protection of flowing argon gas to obtain a high surface area BiCuSeO thermoelectric catalyst material.

[0016] The method for preparing a high surface area thermoelectric catalytic material for CO2 waste gas treatment, as described above, is characterized in that the ball milling in step one uses a ball-to-material ratio of 20:1, a rotation speed of 450 rpm, and a milling time of 2 hours. Under these milling parameters, the resulting mixed powder is more uniform and does not exhibit powder agglomeration.

[0017] The preparation method of the high surface area thermoelectric catalytic material for CO2 waste gas treatment described above is characterized in that the sintering process in step two is as follows: The mixed powder is manually compacted into a cylindrical alumina crucible, and a 2mm thick layer of B2O3 powder is applied to the surface of the compacted mixed powder. Then, the crucible is placed in a box-type resistance furnace, and the temperature is raised to 300℃ at a rate of 15℃ / min and held for 10min, then raised to 550℃ at a rate of 10℃ / min and held for 10min, and finally raised to 600℃~700℃ at a rate of 5℃ / min and held for 12h. After breaking the crucible, blocky BiCuSeO base material is obtained. In this invention, B2O3 powder is used as a flux. During the sintering process, the B2O3 powder melts and forms a molten glassy state, which serves to isolate the air.

[0018] The above-mentioned method for preparing a high surface area thermoelectric catalytic material for CO2 waste gas treatment is characterized in that, in step three, the mass ratio of multi-scale polystyrene powder to blocky BiCuSeO parent material is 1:4, and the multi-scale polystyrene powder is composed of polystyrene powder with a particle size of 5nm-50nm and polystyrene powder with a particle size of 50nm-1000nm in a 1:1 mass ratio. This composition of the pore-forming agent, multi-scale polystyrene powder, ensures that the BiCuSeO thermoelectric catalytic material has a hierarchical porous structure and a porosity greater than 30%.

[0019] The method for preparing a high surface area thermoelectric catalytic material for CO2 waste gas treatment, as described above, is characterized in that the ball milling in step three uses a ball-to-material ratio of 20:1, a rotation speed of 350 rpm, and a milling time of 1 hour. The preform powder obtained under these milling parameters is uniform, especially with a uniform distribution of the multi-scale pore-forming agent, preventing powder agglomeration.

[0020] The above-mentioned method for preparing a high surface area thermoelectric catalytic material for CO2 waste gas treatment is characterized in that, in step three, the preform powder is filled into a 316 stainless steel mold with a diameter × height of φ20mm × 6mm in the filling area. During filling, the mold is vibrated while the material is added. Then, the filled mold is placed on the stage of a powder tablet press and cold-pressed under a pressure of 150MPa with a deformation of 50%. After demolding, a BiCuSeO preform with a size of φ20mm × 3mm is obtained.

[0021] The preparation method of the high surface area thermoelectric catalytic material for CO2 waste gas treatment is characterized in that the solid-state sintering process in step four is as follows: the temperature is raised to 300°C at a rate of 15°C / min and held for 10 min, then raised to 450°C at a rate of 10°C / min and held for 10 min, and finally raised to 500°C to 650°C at a rate of 5°C / min and held for 10 h, and then cooled to room temperature with the furnace, and the entire heating, holding and cooling process is protected by flowing argon gas.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention involves mixing raw material powders and then using a fluxing method to prepare BiCuSeO master material. A multi-scale pore-forming agent is then added for cold pressing and solid-state sintering to prepare a BiCuSeO thermoelectric catalytic material with a multi-level pore structure. This improves the surface area of ​​the BiCuSeO thermoelectric catalytic material and achieves an extremely high CO2 waste gas conversion rate, making it suitable for CO2 waste gas treatment.

[0024] 2. This invention employs a process combining fluxing and solid-state sintering. By controlling the temperature of both processes, high-purity BiCuSeO thermoelectric catalytic materials free of impurities are prepared, ensuring the high catalytic activity of the BiCuSeO thermoelectric catalytic materials. Furthermore, the preparation process of this invention is short, with significant advantages of low cost and no pollution, making it suitable for engineering applications.

[0025] 3. The high surface area BiCuSeO thermoelectric catalytic material prepared by this invention has a multi-level porous structure with a porosity of 30% to 37%, and the effective contact area is 15 to 17 times that of bulk materials of the same size. This porosity range effectively ensures the excellent pore connectivity inside the BiCuSeO thermoelectric catalytic material, increases the proportion of open pores, and reduces the content of closed pores.

[0026] 4. The high surface area BiCuSeO thermoelectric catalytic material prepared by this invention has excellent thermoelectric catalytic effect, with a CO2 conversion rate of over 24% at 342℃, which is even higher than the theoretical limit of conversion efficiency. Under the same Seebeck voltage, it is 5 times the conversion rate of the bulk non-porous BiCuSeO thermoelectric catalytic material.

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is a physical image of the high surface area BiCuSeO thermoelectric catalytic material prepared in Example 1 of this invention.

[0029] Figure 2 This is a microscopic image of the internal pore morphology of the high surface area BiCuSeO thermoelectric catalytic material prepared in Example 1 of this invention.

[0030] Figure 3 This is a graph showing the composition detection results of the high surface area BiCuSeO thermoelectric catalytic material prepared in Example 1 of this invention.

[0031] Figure 4 This is a graph showing the phase detection results of the high surface area BiCuSeO thermoelectric catalytic material prepared in Example 1 of this invention.

[0032] Figure 5 This is a comparison chart of the CO2 conversion rate test results and the theoretical conversion rate limit of the high surface area BiCuSeO thermoelectric catalytic material prepared in Example 1 of this invention.

[0033] Figure 6 This is a comparison chart of the CO2 conversion rate test results of the high surface area BiCuSeO thermoelectric catalytic material prepared in Example 1 of the present invention and the CO2 conversion rate of the bulk non-porous BiCuSeO thermoelectric catalytic material. Detailed Implementation

[0034] Example 1

[0035] This embodiment includes the following steps:

[0036] Step 1: Raw material mixing: Based on the atomic percentage of each element in BiCuSeO, Bi2O3 powder, Bi powder, Cu powder, and Se powder with a mass purity greater than 99% are used as raw materials. The raw materials are weighed according to a mass ratio of 2.33:1.17:1:1.18. 80g of the weighed raw material powder is poured into an agate ball mill jar and agate grinding balls are added according to a ball-to-material ratio of 20:1. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling at a speed of 450 rpm for 2 hours to obtain a mixed powder.

[0037] Step 2: Preparation of BiCuSeO base material by flux method: The mixed powder obtained in Step 1 is loaded into a cylindrical alumina crucible and manually compacted with a spatula. A 2mm thick layer of B2O3 powder is then placed on the surface of the compacted mixed powder as a flux. The crucible is then placed in a box-type resistance furnace and heated in stages. The temperature is increased to 300℃ at a rate of 15℃ / min and held for 10min. Then, the temperature is increased to 550℃ at a rate of 10℃ / min and held for 10min. Finally, the temperature is increased to 600℃ at a rate of 5℃ / min and held for 12h. The furnace is then cooled to room temperature. After the crucible is broken, blocky BiCuSeO base material is obtained.

[0038] Step 3, Pore Formation and Cold Pressing: Place the blocky BiCuSeO base material obtained in Step 2 into an agate ball mill jar, add 20g of polystyrene powder as a pore-forming agent, and add agate grinding balls at a ball-to-material ratio of 20:1. The polystyrene powder pore-forming agent consists of polystyrene powder with a particle size of 5nm-50nm and 50nm-1000nm in a 1:1 mass ratio. The mass ratio of the polystyrene powder pore-forming agent to the blocky BiCuSeO base material is 1:4. Then, pour the mixture into the agate ball mill jar. The mixture is protected and sealed with argon gas and then placed in a planetary ball mill for ball milling at a speed of 350 rpm for 1 hour to obtain preform powder. The preform powder is then filled into a 316 stainless steel mold with a diameter × height of φ20 mm × 6 mm. During filling, the mold is vibrated while the material is added. The filled mold is then placed on the stage of a powder tablet press and cold-pressed under a pressure of 150 MPa. After demolding, a BiCuSeO preform with a size of φ20 mm × 3 mm is obtained.

[0039] Step 4: Solid-state sintering: The BiCuSeO preform obtained in Step 3 is placed in a tube furnace. Under the protection of flowing argon gas, a staged heating method is used. The temperature is increased to 300℃ at a rate of 15℃ / min and held for 10min. Then, the temperature is increased to 450℃ at a rate of 10℃ / min and held for 10min. Finally, the temperature is increased to 650℃ at a rate of 5℃ / min and held for 10h. Flowing argon gas protection is maintained throughout the entire heating, holding, and cooling process to obtain a high surface area BiCuSeO thermoelectric catalyst material.

[0040] Figure 1 This is a physical image of the high surface area BiCuSeO thermoelectric catalytic material prepared in this embodiment. Figure 1 It can be seen that the high surface area BiCuSeO thermoelectric catalytic material has regular size and visible millimeter-scale pores.

[0041] Figure 2 These are microscopic images of the internal pore morphology of the high surface area BiCuSeO thermoelectric catalytic material prepared in this embodiment. Figure 2It can be seen that the micropores inside this high surface area BiCuSeO thermoelectric catalytic material are micrometer-sized, with excellent connectivity and uniform distribution.

[0042] Figure 3 This is a graph showing the composition detection results of the high surface area BiCuSeO thermoelectric catalytic material prepared in this embodiment. Figure 3 The top right and bottom left images are the compositional spectra of different parts of the BiCuSeO thermoelectric catalytic material in the top left image, respectively. The bottom right image shows the compositional detection results of the top right and bottom left images. Figure 3 It can be seen that the atomic ratio of Bi, Cu, Se and O in different parts of the high surface area BiCuSeO thermoelectric catalytic material is 1:1:1:1, and there are no other impurity elements, indicating that the prepared BiCuSeO thermoelectric catalytic material has high purity.

[0043] Figure 4 This is a phase detection result image of the high surface area BiCuSeO thermoelectric catalyst material prepared in this embodiment. Figure 4 It can be seen that the phase detection results of this high surface area BiCuSeO thermoelectric catalytic material show only the diffraction peaks of the BiCuSeO single phase, indicating that the prepared products are all BiCuSeO phase and do not contain other impurity products.

[0044] Figure 5 This is a comparison chart of the CO2 conversion rate test results and the theoretical conversion limit of the high surface area BiCuSeO thermoelectric catalyst material prepared in this embodiment. Figure 5 It can be seen that the high surface area BiCuSeO thermoelectric catalytic material achieves a CO2 conversion rate of over 24% at 342℃, which is even higher than the theoretical limit of the conversion efficiency.

[0045] Figure 6 This is a comparison chart of the CO2 conversion rate of the high surface area BiCuSeO thermoelectric catalyst prepared in this embodiment and the CO2 conversion rate of the bulk non-porous BiCuSeO thermoelectric catalyst. The bulk non-porous BiCuSeO thermoelectric catalyst was prepared using the method of Example 1 without adding a pore-forming agent. Figure 6 It can be seen that the high surface area BiCuSeO thermoelectric catalytic material has a better thermoelectric catalytic effect, and its conversion rate is 5 times that of the bulk non-porous BiCuSeO thermoelectric catalytic material at a Seebeck voltage of 70mV.

[0046] Example 2

[0047] This embodiment includes the following steps:

[0048] Step 1: Raw material mixing: Based on the atomic percentage of each element in BiCuSeO, Bi2O3 powder, Bi powder, Cu powder, and Se powder with a mass purity greater than 99% are used as raw materials. The raw materials are weighed according to a mass ratio of 2.33:1.17:1:1.18. 80g of the weighed raw material powder is poured into an agate ball mill jar and agate grinding balls are added according to a ball-to-material ratio of 20:1. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling at a speed of 450 rpm for 2 hours to obtain a mixed powder.

[0049] Step 2: Preparation of BiCuSeO base material by flux method: The mixed powder obtained in Step 1 is loaded into a cylindrical alumina crucible and manually compacted with a spatula. A 2 mm thick layer of B2O3 powder is then placed on the surface of the compacted mixed powder as a flux. The crucible is then placed in a box-type resistance furnace and heated to 300℃ at a rate of 15℃ / min and held for 10 min. The temperature is then increased to 550℃ at a rate of 10℃ / min and held for 10 min. Finally, the temperature is increased to 650℃ at a rate of 5℃ / min and held for 12 h. The furnace is then cooled to room temperature. After crushing the crucible, blocky BiCuSeO base material is obtained.

[0050] Step 3, Pore Formation and Cold Pressing: Place the blocky BiCuSeO base material obtained in Step 2 into an agate ball mill jar, add 20g of polystyrene powder as a pore-forming agent, and add agate grinding balls at a ball-to-material ratio of 20:1. The polystyrene powder pore-forming agent consists of polystyrene powder with a particle size of 5nm-50nm and 50nm-1000nm in a 1:1 mass ratio. The mass ratio of the polystyrene powder pore-forming agent to the blocky BiCuSeO base material is 1:4. Then, argon gas is injected into the agate ball mill jar for maintenance. The mixture was protected and sealed, and then placed in a planetary ball mill for ball milling at a speed of 350 rpm for 1 hour to obtain preform powder. The preform powder was then filled into a 316 stainless steel mold with a diameter × height of φ20 mm × 6 mm. During filling, the mold was vibrated while the material was added. The filled mold was then placed on the stage of a powder tablet press and cold-pressed under a pressure of 150 MPa with a deformation of 50%. After demolding, a BiCuSeO preform with a size of φ20 mm × 3 mm was obtained.

[0051] Step 4: Solid-state sintering: The BiCuSeO preform obtained in Step 3 was placed in a tube furnace. Under the protection of flowing argon gas, a staged heating method was used: the temperature was increased to 300℃ at a rate of 15℃ / min and held for 10 min; then increased to 450℃ at a rate of 10℃ / min and held for 10 min; finally, the temperature was increased to 650℃ at a rate of 5℃ / min and held for 10 h. Flowing argon gas protection was maintained throughout the entire heating, holding, and cooling process to obtain a high surface area BiCuSeO thermoelectric catalyst material.

[0052] Example 3

[0053] This embodiment includes the following steps:

[0054] Step 1: Raw material mixing: Based on the atomic percentage of each element in BiCuSeO, Bi2O3 powder, Bi powder, Cu powder, and Se powder with a mass purity greater than 99% are used as raw materials. The raw materials are weighed according to a mass ratio of 2.33:1.17:1:1.18. 80g of the weighed raw material powder is poured into an agate ball mill jar and agate grinding balls are added according to a ball-to-material ratio of 20:1. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling at a speed of 450 rpm for 2 hours to obtain a mixed powder.

[0055] Step 2: Preparation of BiCuSeO base material by flux method: The mixed powder obtained in Step 1 is loaded into a cylindrical alumina crucible and manually compacted with a spatula. A 2 mm thick layer of B2O3 powder is then placed on the surface of the compacted mixed powder as a flux. The crucible is then placed in a box-type resistance furnace and heated to 300℃ at a rate of 15℃ / min and held for 10 min. The temperature is then increased to 550℃ at a rate of 10℃ / min and held for 10 min. Finally, the temperature is increased to 700℃ at a rate of 5℃ / min and held for 12 h. The furnace is then cooled to room temperature. After crushing the crucible, blocky BiCuSeO base material is obtained.

[0056] Step 3, Pore Formation and Cold Pressing: Place the blocky BiCuSeO base material obtained in Step 2 into an agate ball mill jar, add 20g of polystyrene powder as a pore-forming agent, and add agate grinding balls at a ball-to-material ratio of 20:1. The polystyrene powder pore-forming agent consists of polystyrene powder with a particle size of 5nm-50nm and 50nm-1000nm in a 1:1 mass ratio. The mass ratio of the polystyrene powder pore-forming agent to the blocky BiCuSeO base material is 1:4. Then, argon gas is injected into the agate ball mill jar for maintenance. The mixture was protected and sealed, and then placed in a planetary ball mill for ball milling at a speed of 350 rpm for 1 hour to obtain preform powder. The preform powder was then filled into a 316 stainless steel mold with a diameter × height of φ20 mm × 6 mm. During filling, the mold was vibrated while the material was added. The filled mold was then placed on the stage of a powder tablet press and cold-pressed under a pressure of 150 MPa with a deformation of 50%. After demolding, a BiCuSeO preform with a size of φ20 mm × 3 mm was obtained.

[0057] Step 4: Solid-state sintering: The BiCuSeO preform obtained in Step 3 was placed in a tube furnace. Under the protection of flowing argon gas, a staged heating method was used: the temperature was increased to 300℃ at a rate of 15℃ / min and held for 10 min; then increased to 450℃ at a rate of 10℃ / min and held for 10 min; finally, the temperature was increased to 650℃ at a rate of 5℃ / min and held for 10 h. Flowing argon gas protection was maintained throughout the entire heating, holding, and cooling process to obtain a high surface area BiCuSeO thermoelectric catalyst material.

[0058] Example 4

[0059] This embodiment includes the following steps:

[0060] Step 1: Raw material mixing: Based on the atomic percentage of each element in BiCuSeO, Bi2O3 powder, Bi powder, Cu powder, and Se powder with a mass purity greater than 99% are used as raw materials. The raw materials are weighed according to a mass ratio of 2.33:1.17:1:1.18. 80g of the weighed raw material powder is poured into an agate ball mill jar and agate grinding balls are added according to a ball-to-material ratio of 20:1. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling at a speed of 450 rpm for 2 hours to obtain a mixed powder.

[0061] Step 2: Preparation of BiCuSeO base material by flux method: The mixed powder obtained in Step 1 is loaded into a cylindrical alumina crucible and manually compacted with a spatula. A 2 mm thick layer of B2O3 powder is then placed on the surface of the compacted mixed powder as a flux. The crucible is then placed in a box-type resistance furnace and heated to 300℃ at a rate of 15℃ / min and held for 10 min. The temperature is then increased to 550℃ at a rate of 10℃ / min and held for 10 min. Finally, the temperature is increased to 650℃ at a rate of 5℃ / min and held for 12 h. The furnace is then cooled to room temperature. After crushing the crucible, blocky BiCuSeO base material is obtained.

[0062] Step 3, Pore Formation and Cold Pressing: Place the blocky BiCuSeO base material obtained in Step 2 into an agate ball mill jar, add 20g of polystyrene powder as a pore-forming agent, and add agate grinding balls at a ball-to-material ratio of 20:1. The polystyrene powder pore-forming agent consists of polystyrene powder with a particle size of 5nm-50nm and 50nm-1000nm in a 1:1 mass ratio. The mass ratio of the polystyrene powder pore-forming agent to the blocky BiCuSeO base material is 1:4. Then, argon gas is injected into the agate ball mill jar for maintenance. The mixture was protected and sealed, and then placed in a planetary ball mill for ball milling at a speed of 350 rpm for 1 hour to obtain preform powder. The preform powder was then filled into a 316 stainless steel mold with a diameter × height of φ20 mm × 6 mm. During filling, the mold was vibrated while the material was added. The filled mold was then placed on the stage of a powder tablet press and cold-pressed under a pressure of 150 MPa with a deformation of 50%. After demolding, a BiCuSeO preform with a size of φ20 mm × 3 mm was obtained.

[0063] Step 4: Solid-state sintering: The BiCuSeO preform obtained in Step 3 was placed in a tube furnace. Under the protection of flowing argon gas, a staged heating method was used: the temperature was increased to 300℃ at a rate of 15℃ / min and held for 10 min; then increased to 450℃ at a rate of 10℃ / min and held for 10 min; finally, the temperature was increased to 500℃ at a rate of 5℃ / min and held for 10 h. Flowing argon gas protection was maintained throughout the entire heating, holding, and cooling process to obtain a high surface area BiCuSeO thermoelectric catalyst material.

[0064] Example 5

[0065] This embodiment includes the following steps:

[0066] Step 1: Raw material mixing: Based on the atomic percentage of each element in BiCuSeO, Bi2O3 powder, Bi powder, Cu powder, and Se powder with a mass purity greater than 99% are used as raw materials. The raw materials are weighed according to a mass ratio of 2.33:1.17:1:1.18. 80g of the weighed raw material powder is poured into an agate ball mill jar and agate grinding balls are added according to a ball-to-material ratio of 20:1. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling at a speed of 450 rpm for 2 hours to obtain a mixed powder.

[0067] Step 2: Preparation of BiCuSeO base material by flux method: The mixed powder obtained in Step 1 is loaded into a cylindrical alumina crucible and manually compacted with a spatula. A 2 mm thick layer of B2O3 powder is then placed on the surface of the compacted mixed powder as a flux. The crucible is then placed in a box-type resistance furnace and heated to 300℃ at a rate of 15℃ / min and held for 10 min. The temperature is then increased to 550℃ at a rate of 10℃ / min and held for 10 min. Finally, the temperature is increased to 650℃ at a rate of 5℃ / min and held for 12 h. The furnace is then cooled to room temperature. After crushing the crucible, blocky BiCuSeO base material is obtained.

[0068] Step 3, Pore Formation and Cold Pressing: Place the blocky BiCuSeO base material obtained in Step 2 into an agate ball mill jar, add 20g of polystyrene powder as a pore-forming agent, and add agate grinding balls at a ball-to-material ratio of 20:1. The polystyrene powder pore-forming agent consists of polystyrene powder with a particle size of 5nm-50nm and 50nm-1000nm in a 1:1 mass ratio. The mass ratio of the polystyrene powder pore-forming agent to the blocky BiCuSeO base material is 1:4. Then, argon gas is injected into the agate ball mill jar for maintenance. The mixture was protected and sealed, and then placed in a planetary ball mill for ball milling at a speed of 350 rpm for 1 hour to obtain preform powder. The preform powder was then filled into a 316 stainless steel mold with a diameter × height of φ20 mm × 6 mm. During filling, the mold was vibrated while the material was added. The filled mold was then placed on the stage of a powder tablet press and cold-pressed under a pressure of 150 MPa with a deformation of 50%. After demolding, a BiCuSeO preform with a size of φ20 mm × 3 mm was obtained.

[0069] Step 4: Solid-state sintering: The BiCuSeO preform obtained in Step 3 was placed in a tube furnace. Under the protection of flowing argon gas, a staged heating method was used: the temperature was increased to 300℃ at a rate of 15℃ / min and held for 10 min; then increased to 450℃ at a rate of 10℃ / min and held for 10 min; finally, the temperature was increased to 600℃ at a rate of 5℃ / min and held for 10 h. Flowing argon gas protection was maintained throughout the entire heating, holding, and cooling process to obtain a high surface area BiCuSeO thermoelectric catalyst material.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a high surface area BiCuSeO thermoelectric catalytic material for CO2 waste gas treatment, characterized in that, The method includes the following steps: Step 1: Raw material mixing: Based on the atomic percentage of each element in BiCuSeO, Bi2O3 powder, Bi powder, Cu powder, and Se powder with a mass purity greater than 99% are used as raw materials. The raw materials are weighed according to a mass ratio of 2.33:1.17:1:1.

18. The weighed raw material powder is poured into an agate ball mill jar and agate grinding balls are added. Then, argon gas is injected into the agate ball mill jar for protection and it is sealed. The jar is then placed in a planetary ball mill for ball milling to obtain mixed powder. Step 2: Preparation of BiCuSeO base material by flux method: Using B2O3 powder as flux, the mixed powder obtained in step 1 is loaded into a cylindrical alumina crucible and manually compacted. A 2mm thick layer of B2O3 powder is then placed on the surface of the compacted mixed powder and sintered in a box-type resistance furnace. After removal, a block-shaped BiCuSeO base material is obtained. Step 3, Pore Formation and Cold Pressing: The blocky BiCuSeO preform obtained in Step 2 is placed in an agate ball mill jar. Multi-scale polystyrene powder is added as a pore-forming agent and agate grinding balls are placed in it. The multi-scale polystyrene powder is composed of polystyrene powder with a particle size of 5nm~50nm and a particle size of 50nm~1000nm in a 1:1 mass ratio. Then, argon gas is injected into the agate ball mill jar for protection and sealing. The jar is then placed in a planetary ball mill for ball milling to obtain preform powder. The preform powder is then filled into a mold for cold pressing to obtain the BiCuSeO preform. Step 4: Solid-state sintering: The BiCuSeO preform obtained in step 3 is placed in a tube furnace and solid-state sintering is carried out under the protection of flowing argon gas to obtain a high surface area BiCuSeO thermoelectric catalyst material. The sintering process described in step two is as follows: using a staged heating method, the temperature is raised to 300℃ at a rate of 15℃ / min and held for 10min, then raised to 550℃ at a rate of 10℃ / min and held for 10min, and finally raised to 600℃~700℃ at a rate of 5℃ / min and held for 12h. After breaking the crucible, blocky BiCuSeO base material is obtained. In step three, the mass ratio of the multi-scale polystyrene powder to the blocky BiCuSeO matrix is ​​1:

4. The solid-state sintering process described in step four is as follows: a staged heating method is adopted, heating to 300℃ at a rate of 15℃ / min and holding for 10min, then heating to 450℃ at a rate of 10℃ / min and holding for 10min, and finally heating to 500℃~650℃ at a rate of 5℃ / min and holding for 10h, and then cooling to room temperature with the furnace, and maintaining flowing argon gas protection throughout the entire heating, holding and cooling process.

2. The method for preparing a high surface area BiCuSeO thermoelectric catalytic material for CO2 waste gas treatment according to claim 1, characterized in that, The ball milling process described in step one uses a ball-to-material ratio of 20:1, a rotation speed of 450 rpm, and a milling time of 2 hours.

3. The method for preparing a high surface area BiCuSeO thermoelectric catalytic material for CO2 waste gas treatment according to claim 1, characterized in that, In step three, the ball milling process uses a ball-to-material ratio of 20:1, a rotation speed of 350 rpm, and a milling time of 1 hour.

4. The method for preparing a high surface area BiCuSeO thermoelectric catalytic material for CO2 waste gas treatment according to claim 1, characterized in that, In step three, the precast powder is filled into the filler area, which has a diameter × height of [missing value]. The 20mm x 6mm 316 stainless steel mold is filled with material while the mold is vibrated. The filled mold is then placed on the stage of a powder tablet press and cold-pressed under 150MPa pressure with a deformation of 50%. The resulting product has dimensions of [missing dimensions]. 20mm×3mm BiCuSeO preform.

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