Preparation method of modified BN two-dimensional catalytic material and application of modified BN two-dimensional catalytic material in methane conversion

Abstract

The invention relates to the technical field of preparation of catalytic materials, in particular to a preparation method of a modified BN two-dimensional catalytic material and application of the modified BN two-dimensional catalytic material in methane conversion. S2, preparing a boron nitride material; s3, modification of a boron nitride material; and S4, post-processing. The modeling modification liquid prepared from the oxygen stability enhancing liquid and the boron nitride material form a heterojunction structure, separation of photo-induced electron-hole pairs is remarkably promoted, solar driven catalytic reaction kinetics is improved, oxygen doping sites on the surface of the boron nitride material can be dynamically adjusted, oxygen elements are prevented from being lost in the reaction, and the service life of the boron nitride material is prolonged. The long-acting stability of the catalytic material is ensured. According to the method, the efficiency of solar catalytic methane conversion is improved, a large amount of carbon dioxide is generated, high-yield generation of high-value chemicals such as methanol or formaldehyde under the mild condition is achieved, and a new way is provided for green methane conversion.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of catalytic materials, and specifically to a preparation method of a modified BN two-dimensional catalytic material and its application in methane conversion. Background Art

[0002] Methane (CH4), as an important component of natural gas, its chemical conversion has become one of the research hotspots in the field of energy chemistry. Especially the direct conversion of methane into methanol (CH3OH) and formaldehyde (CH2O) has attracted much attention due to their wide applications in energy storage, chemical production, and environmental protection. However, traditional methane conversion processes often face a series of challenges. The traditional methane-to-methanol process usually involves multiple steps of reactions and severe operating conditions. For example, the indirect conversion method requires partial oxidation of methane to generate carbon monoxide (CO) and hydrogen (H2) first, and then further reactions to obtain methanol. This multi-step process not only requires high-temperature, high-pressure and other energy-consuming conditions, but also easily produces by-products (such as CO2, CO, etc.), resulting in low reaction efficiency and heavy environmental burden. In addition, the easy deactivation and high cost of catalysts in traditional processes also limit the popularization and application of the process.

[0003] Compared with traditional processes, in recent years, the methane conversion technology based on solar-driven catalysis has shown more green and efficient characteristics. Solar-driven catalysis uses sunlight as the driving force, and through the design of efficient solar-driven catalytic materials, the selective oxidation of methane to generate methanol is realized. The significant advantage of this process lies in the mild reaction conditions, high energy utilization rate, and less by-product generation, meeting the development needs of green chemistry. In addition, the solar-driven catalytic process has a lower material cost and is more environmentally friendly during the reaction process. However, the solar-driven catalytic methane conversion technology still faces some challenges, such as improving the conversion rate of methane and the yield of methanol. By continuously innovating the design of catalytic materials and optimizing the reaction conditions, it is expected to popularize the solar-driven catalytic technology to industrial applications and open up new paths for the efficient utilization of methane resources and green chemistry.

[0004] Currently, the catalytic materials used for solar-driven catalytic methane conversion mainly focus on two-dimensional metal oxides (such as TiO2, ZnO, etc.). These materials have good light absorption properties, but they are prone to product overoxidation in the presence of oxygen. Therefore, there is an urgent need to design an efficient solar-driven catalytic material to improve methanol yield while suppressing product overoxidation. In the selection of catalytic materials, some two-dimensional non-metallic materials have gradually attracted attention. Among them, the non-toxic and harmless BN material has been discovered and applied to solar-driven catalytic methane conversion. This material only produces C1 compounds (methanol and formaldehyde) during the solar-driven catalytic methane conversion process and will not produce other peroxides (CO, CO2). Therefore, it is an excellent catalyst for solar-driven catalytic methane conversion. However, the product yield obtained from a single BN material is not high, and currently, the BN material is modified to be more suitable for solar-driven catalytic methane conversion. The following are some publicly disclosed methods for modifying BN materials, but they still have deficiencies, and the specific content is as follows.

[0005] CN119463532A discloses a method for ozone-modifying hexagonal boron nitride, belonging to the field of inorganic filler modification methods. In this invention, hexagonal boron nitride is heat-treated at low temperature and then mixed with water to form a slurry, and then ozone is introduced for oxidation treatment. Finally, a surface modifier is used for modification to obtain modified hexagonal boron nitride. After the hydrolyzable groups in the surface modifier combine with the hydroxyl groups on the surface of boron nitride, more carbon-containing long chains are bonded to the surface of boron nitride. Therefore, the higher the amount of the added modifier, the higher the carbon content; the excess free modifier can be removed by methyl ethyl ketone. At this time, the measured carbon content is the content of the surface modifier grafted onto the surface of boron nitride. The higher the carbon content, the more surface modifiers are successfully grafted. However, this method requires the use of methyl ethyl ketone to remove the free modifier, and it is prone to the drawback of incomplete removal.

[0006] CN119307073A discloses a preparation method of a highly thermally conductive polymer with modified boron nitride as a filler, which relates to the field of polymer thermal conductivity technology. The method for preparing modified boron nitride nanosheets in this invention is as follows: Add boron nitride nanosheets to 10 ml of tetrahydrofuran, under the condition of a power of 400 W, ultrasonically disperse for 10 min, then add a modifier, react at 40 °C for 2 h, and then remove tetrahydrofuran in a rotary evaporator at 65 °C and a pressure of 400 mmHg at a rotation speed of 100 r / min. Then transfer it to 40 ml of deionized water and dry it in an 80 °C oven for 12 h to obtain modified boron nitride nanosheets. By aminating and modifying the boron nitride nanosheets, its structure and properties are more stable, and the interfacial compatibility and dispersibility between the boron nitride nanosheets and the polymer matrix are effectively enhanced. However, this method requires too many temperature change steps for synthesis, and the steps are relatively cumbersome. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a preparation method of a modified BN two-dimensional catalytic material and its application in methane conversion.

[0008] To achieve the above object, the present invention provides the following technical solutions: A preparation method of a modified BN two-dimensional catalytic material, comprising the following preparation steps: S1. Material mixing: Add boric acid and urea into a beaker according to a mass ratio of 12:1, and mechanically stir at a speed of 400 - 500 r / min for 0.5 - 2 h to fully mix the two, obtaining a white powder; S2. Preparation of boron nitride material: Transfer the white powder obtained in step S1 to a porcelain boat, place it in a tube furnace for heat treatment, then naturally cool to room temperature, and finally perform grinding treatment to obtain a boron nitride material; S3. Modification of boron nitride material: Take a quantitative amount of the boron nitride material prepared in step S2 and mix it with a modeling modification liquid, place it in a beaker, add ultrapure water and stir evenly, then add a synergistic modification liquid, continue to stir for 15 - 20 min, and then heat the reaction device in a water bath at a temperature of 80 °C for a reaction time of 3 - 4 h to obtain a modified boron nitride material; S4. Post-treatment: Filter and separate the modified boron nitride material through a suction filtration device, repeatedly wash it with ultrapure water, then precipitate the residual solid on the filter paper, place the obtained solid in a vacuum drying oven for drying treatment, and then perform grinding to obtain the modified BN two-dimensional catalytic material; The preparation of the modeling modification liquid includes the following steps: S11. According to mass parts, add 6 - 10 parts of zinc oxide and 0.5 - 1 part of polyethylene glycol into 50 - 60 parts of ultrapure water, and ultrasonically disperse at a frequency of 40 kHz for 25 - 30 min to obtain a uniform suspension; S12. Add 2 - 5 parts of an oxygen stability enhancing liquid to the suspension obtained in step S11, and stir at a speed of 500 - 600 r / min at room temperature for 15 - 20 min; S13. Add 1.5 - 2 parts of aluminum nitrate to the mixed liquid obtained in step S12, and stir at a speed of 450 - 500 r / min at room temperature for 25 - 30 min to obtain the modeling modification liquid.

[0009] Preferably, the preparation of the oxygen stability enhancing liquid includes the following steps: S121. According to mass parts, dissolve 50 - 55 parts of ammonium cerium nitrate and 8 - 10 parts of lanthanum nitrate in 180 - 200 parts of ultrapure water, and stir at a speed of 300 - 400 r / min at 40 °C for 15 - 20 min; S122. Add 25 - 30 parts of citric acid to the solution obtained in step S121, and continue to stir at a speed of 350 - 400 r / min for 0.5 - 1 h to obtain an oxygen stability enhancing solution.

[0010] Preferably, the synergistic modification solution is composed of phosphomolybdic acid, glacial acetic acid and water with a mass ratio of 0.05 - 0.1:1:10.

[0011] Preferably, the specific control conditions for the heat treatment in step S2 are a heating rate of 5℃ / s, a holding time of 5 h, maintaining a nitrogen atmosphere during this period, an initial temperature of 25℃, and a final temperature of 1000℃.

[0012] Preferably, the mass ratio of the boron nitride material, the modeling modification solution, and the synergistic modification solution in step S3 is 1:1:0.1 - 0.2.

[0013] Preferably, the stirring speed in step S3 is 500 - 600 r / min.

[0014] Preferably, the control conditions for the drying treatment in step S4 are a drying temperature of 60℃ and a duration of 12 h.

[0015] Application of a modified BN two - dimensional catalytic material prepared according to the above - mentioned preparation method as a catalyst for solar - driven methane conversion reaction.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The preparation process of the present invention is simple, the energy consumption of the solar - driven catalytic methane conversion step is relatively low, and it has an obvious cost advantage. At the same time, it helps to improve the efficiency of solar - catalytic methane conversion and produce a large amount of carbon dioxide, realizing the generation of high - value chemicals such as methanol or formaldehyde with high yield under mild conditions, providing a new way for green methane conversion.

[0017] 2. The modeling modification solution prepared by the present invention through the oxygen stability enhancing solution forms a heterojunction structure with the boron nitride material, significantly promoting the separation of photo - generated electron - hole pairs, improving the kinetics of solar - driven catalytic reactions, and can also dynamically adjust the oxygen - doped sites on the surface of the boron nitride material to prevent the loss of oxygen elements during the reaction, ensuring the long - term stability of the catalytic material.

[0018] 3. The synergistic effect of the modeling modification solution, the oxygen stability enhancing solution and the synergistic modification solution in the present invention provides oxygen elements, which can avoid the peroxidation of the products methanol or formaldehyde during the reaction, thereby increasing the yield of methanol or formaldehyde. It changes the surface structure of the boron nitride material, enabling it to obtain excellent solar - driven catalytic performance. This catalytic material can selectively generate methanol or formaldehyde from methane at normal temperature and pressure, and its yield is close to 1000 μmol·g -1 , realizing the rational utilization of methane resources. Description of the Drawings

[0019] Figure 1 This is the process flow chart for the preparation of the modified BN two-dimensional catalytic material of the present invention; Figure 2 This is the process flow chart for the preparation of the modeling modification liquid of the present invention; Figure 3 This is the process flow chart for the preparation of the oxygen stability enhancement liquid of the present invention; Figure 4 This is the transmission electron microscope morphology diagram of the modified BN two-dimensional catalytic material obtained in Example 1 of the present invention; Figure 5 This is the methanol yield diagram of the solar-driven catalytic methane conversion of the modified BN two-dimensional catalytic materials prepared in Example 1, Example 2 and Comparative Example 1 of the present invention; Figure 6 This is the CO2 yield diagram of the solar-driven catalytic methane conversion of the modified BN two-dimensional catalytic materials prepared in Example 1, Example 2 and Comparative Example 1 of the present invention. Detailed implementation manners

[0020] Next, the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] Please refer to Figure 1-6 , the present invention provides a technical solution: Example 1 A preparation method of a modified BN two-dimensional catalytic material: Before preparing the modified BN two-dimensional catalytic material, the preparation of the modeling modification liquid and the oxygen stability enhancement liquid is carried out first: The preparation of the modeling modification liquid includes the following steps: S11. Add 12 g of zinc oxide and 1 g of polyethylene glycol to 100 ml of ultrapure water, and ultrasonically disperse for 25 min at a frequency of 40 kHz to obtain a uniform suspension; S12. Add 4 g of the oxygen stability enhancement liquid to the suspension obtained in step S11, and stir at a rotation speed of 500 r / min at room temperature for 15 min; S13. Add 3 g of aluminum nitrate to the mixed liquid obtained in step S12, and stir at a rotation speed of 450 r / min at room temperature for 25 min to obtain the modeling modification liquid; The preparation of the oxygen stability enhancement liquid includes the following steps: S121. Dissolve 50 g of ammonium cerium(IV) nitrate and 8 g of lanthanum nitrate in 180 ml of ultrapure water, and stir at a speed of 300 r / min for 15 min at 40 °C; S122. Add 25 g of citric acid to the solution obtained in step S121, and continue to stir at a speed of 350 r / min for 0.5 h to obtain an oxygen stability enhancing solution.

[0022] S1. Material mixing: Add boric acid and urea to a beaker according to a mass ratio of 12:1, and mechanically stir at a speed of 400 r / min for 0.5 h to fully mix the two to obtain a white powder; S2. Preparation of boron nitride material: Transfer the white powder obtained in step S1 to a porcelain boat, place it in a tubular furnace for heat treatment. The specific control conditions for heat treatment are a heating rate of 5 °C / s, a holding time of 5 h, maintaining a nitrogen atmosphere during this period, an initial temperature of 25 °C, a final temperature of 1000 °C, then naturally cool to room temperature, and finally perform grinding treatment to obtain a boron nitride material; S3. Modification of boron nitride material: Take 100 g of the boron nitride material prepared in step S2 and mix it with 100 g of the modeling modification liquid, place it in a beaker, add ultrapure water and stir evenly at a speed of 500 r / min, then add 10 g of the co-modification liquid (consisting of 0.5 g of phosphomolybdic acid, 10 g of glacial acetic acid and 100 ml of water, take 10 g of it), continue to stir at a speed of 500 r / min for 15 min, and then heat the reaction device in a water bath at 80 °C for a reaction time of 3 h to obtain a modified boron nitride material; S4. Post-treatment: Filter and separate the modified boron nitride material through a suction filtration device, and wash it repeatedly with ultrapure water, then precipitate the residual solid on the filter paper, place the obtained solid in a vacuum drying oven for drying treatment. The control conditions for drying treatment are a drying temperature of 60 °C and a duration of 12 h, and then perform grinding to obtain the modified BN two-dimensional catalytic material.

[0023] Example 2 A preparation method of a modified BN two-dimensional catalytic material: Before preparing the modified BN two-dimensional catalytic material, first prepare the modeling modification liquid and the oxygen stability enhancing solution: The preparation of the modeling modification liquid includes the following steps: S11. Add 20 g of zinc oxide and 2 g of polyethylene glycol to 120 ml of ultrapure water, and ultrasonically disperse at a frequency of 40 kHz for 30 min to obtain a uniform suspension; S12. Add 10 g of the oxygen stability enhancing solution to the suspension obtained in step S11, and stir at a speed of 600 r / min at room temperature for 20 min; S13. Add 4 g of aluminum nitrate to the mixed solution obtained in step S12, and stir at a speed of 500 r / min at room temperature for 30 min to obtain a modeling modification solution; The preparation of the oxygen stability enhancement solution includes the following steps: S121. Dissolve 55 g of ammonium cerium nitrate and 10 g of lanthanum nitrate in 200 ml of ultrapure water, and stir at a speed of 400 r / min at 40 °C for 20 min; S122. Add 30 g of citric acid to the solution obtained in step S121, and continue to stir at a speed of 400 r / min for 1 h to obtain an oxygen stability enhancement solution.

[0024] S1. Material mixing: Add boric acid and urea to a beaker according to a mass ratio of 12:1, and mechanically stir at a speed of 500 r / min for 2 h to fully mix the two to obtain a white powder; S2. Preparation of boron nitride material: Transfer the white powder obtained in step S1 to a porcelain boat, place it in a tubular furnace for heat treatment. The specific control conditions for heat treatment are a heating rate of 5 °C / s, a holding time of 5 h, maintaining a nitrogen atmosphere during this period, an initial temperature of 25 °C, a final temperature of 1000 °C, then naturally cool to room temperature, and finally perform grinding treatment to obtain a boron nitride material; S3. Modification of boron nitride material: Take 100 g of the boron nitride material prepared in step S2 and mix it with 100 g of the modeling modification solution, place it in a beaker, add ultrapure water and stir evenly at a speed of 600 r / min, then add 20 g of a synergistic modification solution (consisting of 1 g of phosphomolybdic acid, 10 g of glacial acetic acid and 100 ml of water, take 20 g of it), continue to stir at a speed of 600 r / min for 20 min, and then heat the reaction device in a water bath at 80 °C for a reaction time of 4 h to obtain a modified boron nitride material; S4. Post-treatment: Filter and separate the modified boron nitride material through a suction filtration device, repeatedly wash it with ultrapure water, then precipitate the remaining solid on the filter paper, place the obtained solid in a vacuum drying oven for drying treatment. The control conditions for drying treatment are a drying temperature of 60 °C and a duration of 12 h, and then perform grinding to obtain a modified BN two-dimensional catalytic material.

[0025] Example 3 A preparation method of a modified BN two-dimensional catalytic material: Before preparing the modified BN two-dimensional catalytic material, first prepare the modeling modification solution and the oxygen stability enhancement solution: The preparation of the modeling modification solution includes the following steps: S11. Add 15 g of zinc oxide and 1.5 g of polyethylene glycol to 110 ml of ultrapure water, and ultrasonically disperse at a frequency of 40 kHz for 27 min to obtain a uniform suspension; Add 5 g of oxygen stability enhancing liquid to the suspension obtained in step S11, and stir at a speed of 550 r / min at room temperature for 17 min; Add 3.5 g of aluminum nitrate to the mixture obtained in step S12, and stir at a speed of 470 r / min at room temperature for 27 min to obtain a modeling modification liquid; The preparation of the oxygen stability enhancing liquid includes the following steps: Dissolve 52 g of ammonium cerium nitrate and 9 g of lanthanum nitrate in 190 ml of ultrapure water, and stir at a speed of 350 r / min at 40 °C for 17 min; Add 27 g of citric acid to the solution obtained in step S121, and continue to stir at a speed of 370 r / min for 0.7 h to obtain the oxygen stability enhancing liquid.

[0026] S1. Material mixing: Add boric acid and urea to a beaker according to a mass ratio of 12:1, and mechanically stir at a speed of 450 r / min for 1 h to fully mix the two to obtain a white powder; S2. Preparation of boron nitride material: Transfer the white powder obtained in step S1 to a porcelain boat, place it in a tubular furnace for heat treatment. The specific control conditions for heat treatment are a heating rate of 5 °C / s, a holding time of 5 h, maintaining a nitrogen atmosphere during this period, an initial temperature of 25 °C, a final temperature of 1000 °C, then naturally cool to room temperature, and finally perform grinding treatment to obtain the boron nitride material; S3. Modification of boron nitride material: Take 100 g of the boron nitride material prepared in step S2 and mix it with 100 g of the modeling modification liquid, place it in a beaker, add ultrapure water and stir evenly at a speed of 550 r / min, then add 15 g of the synergistic modification liquid (composed of 0.7 g of phosphomolybdic acid, 10 g of glacial acetic acid and 100 ml of water, take 15 g of it), continue to stir at a speed of 550 r / min for 17 min, and then heat the reaction device in a water bath at 80 °C for a reaction time of 3.5 h to obtain the modified boron nitride material; S4. Post-treatment: Filter and separate the modified boron nitride material through a suction filtration device, and repeatedly wash it with ultrapure water, then precipitate the residual solid on the filter paper, place the obtained solid in a vacuum drying oven for drying treatment. The control conditions for drying treatment are a drying temperature of 60 °C and a duration of 12 h, and then perform grinding to obtain the modified BN two-dimensional catalytic material.

[0027] Example 4 A preparation method of a modified BN two-dimensional catalytic material: Before preparing the modified BN two-dimensional catalytic material, first prepare the modeling modification liquid and the oxygen stability enhancing liquid: The preparation of the modeling modification liquid includes the following steps: S11. Add 17 g of zinc oxide and 1.7 g of polyethylene glycol to 115 ml of ultrapure water, and ultrasonically disperse them at a frequency of 40 kHz for 29 min to obtain a uniform suspension; S12. Add 8 g of oxygen stability enhancing liquid to the suspension obtained in step S11, and stir at a speed of 570 r / min at room temperature for 19 min; S13. Add 3.8 g of aluminum nitrate to the mixture obtained in step S12, and stir at a speed of 480 r / min at room temperature for 29 min to obtain a modeling modification liquid; The preparation of the oxygen stability enhancing liquid includes the following steps: S121. Dissolve 53 g of ammonium cerium nitrate and 9 g of lanthanum nitrate in 195 ml of ultrapure water, and stir at a speed of 370 r / min at 40 °C for 18 min; S122. Add 28 g of citric acid to the solution obtained in step S121, and continue to stir at a speed of 390 r / min for 0.8 h to obtain the oxygen stability enhancing liquid.

[0028] S1. Material mixing: Add boric acid and urea to a beaker in a mass ratio of 12:1, and mechanically stir at a speed of 480 r / min for 1.5 h to fully mix them to obtain a white powder; S2. Preparation of boron nitride material: Transfer the white powder obtained in step S1 to a porcelain boat, place it in a tube furnace for heat treatment. The specific control conditions for heat treatment are a heating rate of 5 °C / s, a holding time of 5 h, maintaining a nitrogen atmosphere during this period, an initial temperature of 25 °C, a final temperature of 1000 °C, then naturally cool to room temperature, and finally perform grinding treatment to obtain the boron nitride material; S3. Modification of boron nitride material: Take 100 g of the boron nitride material prepared in step S2 and mix it with 100 g of the modeling modification liquid, place it in a beaker, add ultrapure water and stir evenly at a speed of 580 r / min, then add 18 g of the synergistic modification liquid (composed of 0.8 g of phosphomolybdic acid, 10 g of glacial acetic acid and 100 ml of water, take 18 g of it), continue to stir at a speed of 580 r / min for 18 min, and then heat the reaction device in a water bath at 80 °C for a reaction time of 3.5 h to obtain the modified boron nitride material; S4. Post-treatment: Filter and separate the modified boron nitride material through a suction filtration device, wash it repeatedly with ultrapure water, then precipitate the remaining solid on the filter paper, place the obtained solid in a vacuum drying oven for drying treatment. The control conditions for drying treatment are a drying temperature of 60 °C and a duration of 12 h, and then perform grinding to obtain the modified BN two-dimensional catalytic material.

[0029] Comparative Example 1 Comparative Example 1 differs from Example 1 only in that steps S3 and S4 are omitted, and the boron nitride material is directly obtained. The remaining steps are exactly the same in Comparative Example 1 and Example 1.

[0030] Performance test: Take the modified BN two-dimensional catalytic materials prepared in Example 1 and Example 2, and the boron nitride material prepared in Comparative Example 1 for catalytic performance testing. Further name Example 1 and Example 2 as O-BN-1 and O-BN-2, and name Comparative Example 1 as BN. Then use them for the experiment of solar-driven catalytic methane conversion to methanol: Put 20 mg of O-BN-1, O-BN-2, and BN into three transparent closed reactors respectively, add 20 mL of ultrapure water, seal them and place them on a stirring table for stirring; Purge with O2 gas for 10 min to remove impurity gases in the system; Quickly inject 5 mL of dry CH4 gas into the reactor with a sampling needle to ensure that the system is kept at 60 °C; Connect the circulating water cooling system and turn on the xenon lamp for light reaction; During the reaction process, sample 1 mL of gas every 0.5 h for gas chromatography analysis to monitor the reaction process; After the reaction lasts for 2 h, it ends. The whole experimental process is carried out under normal temperature and pressure conditions.

[0031] Attached Figure 3 is the transmission electron microscopy morphology diagram of the modified BN two-dimensional catalytic material obtained in Example 1 of the present invention. It can be observed from the figure that the modified BN material presents a uniform two-dimensional layered structure, and nano-scale heterojunction structures are distributed on the surface, indicating that the modeling modification liquid and the boron nitride matrix have successfully formed an interfacial coupling. The introduction of this heterojunction structure significantly promotes the separation efficiency of photo-generated electron-hole pairs, thereby enhancing the kinetics of solar-driven catalytic reactions. Through Attached Figure 4 it can be known that under normal temperature and pressure, for solar-driven catalytic methane conversion for 2 h, the methanol production obtained is close to 1000 μmol·g -1 , and the methanol production obtained by using Example 2 is lower than that obtained by Example 1. From Attached Figure 5 , using the modified BN two-dimensional catalytic material prepared in Example 1 for solar-driven catalytic reaction, the yield diagram of the product CO2 can be obtained. The results show that under normal temperature and pressure, for solar-driven catalytic methane conversion for 2 h, the CO2 production obtained is relatively low, while the catalytic material obtained by using Example 2 has a higher CO2 production than that of Example 1. The methanol yield of the modified BN two-dimensional catalytic material obtained in Example 1 for solar-driven catalytic methane conversion is higher than that of Example 2, and the CO2 yield of the modified BN two-dimensional catalytic material obtained in Example 2 for solar-driven catalytic methane conversion is higher than that of Example 1. However, the methanol yields and CO2 yields of the modified BN two-dimensional catalytic materials obtained in Example 1 and Example 2 for solar-driven catalytic methane conversion are much higher than those of Comparative Example 1.

[0032] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of a modified two-dimensional BN catalytic material, characterized in that, It includes the following preparation steps: S1. Material mixing: Add boric acid and urea into a beaker according to the mass ratio of 12:1, and mechanically stir at a speed of 400 - 500 r / min for 0.5 - 2 h to fully mix the two, obtaining a white powder; S2. Preparation of boron nitride material: Transfer the white powder obtained in step S1 to a porcelain boat, place it in a tube furnace for heat treatment, then naturally cool to room temperature, and finally perform grinding treatment to obtain the boron nitride material; S3. Modification of boron nitride material: Take a quantitative amount of the boron nitride material prepared in step S2 and mix it with the modeling modification liquid, place it in a beaker, add ultrapure water and stir evenly, then add the synergistic modification liquid, continue to stir for 15 - 20 min, and then heat the reaction device in a water bath at a temperature of 80 °C for a reaction time of 3 - 4 h to obtain the modified boron nitride material; S4. Post-treatment: Filter and separate the modified boron nitride material through a suction filtration device, wash it repeatedly with ultrapure water, then precipitate the residual solid on the filter paper, place the obtained solid in a vacuum drying oven for drying treatment, and then perform grinding to obtain the modified BN two-dimensional catalytic material; The preparation of the said modeling modification liquid includes the following steps: S11. According to mass parts, add 6 - 10 parts of zinc oxide and 0.5 - 1 part of polyethylene glycol into 50 - 60 parts of ultrapure water, and ultrasonically disperse at a frequency of 40 kHz for 25 - 30 min to obtain a uniform suspension; S12. Add 2 - 5 parts of oxygen stability enhancing liquid to the suspension obtained in step S11, and stir at a speed of 500 - 600 r / min at room temperature for 15 - 20 min; S13. Add 1.5 - 2 parts of aluminum nitrate to the mixed liquid obtained in step S12, and stir at a speed of 450 - 500 r / min at room temperature for 25 - 30 min to obtain the modeling modification liquid.

2. The preparation method of a modified BN two-dimensional catalytic material according to claim 1, characterized in that, The preparation of the said oxygen stability enhancing liquid includes the following steps: S121. According to mass parts, dissolve 50 - 55 parts of ammonium cerium nitrate and 8 - 10 parts of lanthanum nitrate in 180 - 200 parts of ultrapure water, and stir at a speed of 300 - 400 r / min at 40 °C for 15 - 20 min; S122. Add 25 - 30 parts of citric acid to the solution obtained in step S121, and continue to stir at a speed of 350 - 400 r / min for 0.5 - 1 h to obtain the oxygen stability enhancing liquid.

3. The preparation method of a modified BN two-dimensional catalytic material according to claim 1, characterized in that, The said synergistic modification liquid is composed of phosphomolybdic acid, glacial acetic acid and water with a mass ratio of 0.05 - 0.1:1:

10.

4. The preparation method of a modified BN two-dimensional catalytic material according to claim 1, characterized in that, The specific control conditions for the heat treatment in step S2 are: the heating rate is 5 °C / s, the holding time is 5 h, maintaining a nitrogen atmosphere during this period, the starting temperature is 25 °C, and the ending temperature is 1000 °C.

5. The preparation method of a modified BN two-dimensional catalytic material according to claim 1, characterized in that, In step S3, the mass ratio of the boron nitride material, the modeling modification liquid, and the synergistic modification liquid is 1:1:0.1 - 0.

2.

6. The preparation method of a modified BN two-dimensional catalytic material according to claim 1, characterized in that, The stirring speed in step S3 is 500 - 600 r / min.

7. The preparation method of a modified BN two-dimensional catalytic material according to claim 1, characterized in that, The control conditions for the drying treatment in step S4 are: the drying temperature is 60 °C, and the duration is 12 h.

8. Use of a modified BN two-dimensional catalytic material prepared by the preparation method according to any one of claims 1-7 as a catalyst for a solar-driven catalytic methane conversion reaction.

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