Modified boron nitride material and method for increasing its carbon dioxide adsorption capacity

Abstract

The application provides a modified boron nitride material and a method for improving the carbon dioxide adsorption capacity thereof, relates to the technical field of adsorption materials, and the modified boron nitride material is a boron nitride material doped with carbon elements and oxygen elements; the content of the oxygen elements in the modified boron nitride material is 28-32%, and the content of the carbon elements is 12-18%. The modified boron nitride material provided by the application has a high carbon dioxide adsorption capacity, and the method can obviously improve the adsorption capacity of the modified boron nitride material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adsorbing materials, and particularly relates to a modified boron nitride material and a method for improving the carbon dioxide adsorption capacity of the modified boron nitride material. BACKGROUND

[0002] In recent years, a series of natural disasters caused by global climate change due to excessive emission of greenhouse gases has made people gradually realize the urgency of developing carbon neutralization and carbon negative emission technology. CO2 is the biggest culprit of global warming, and developing CO2 capture technology is the key to achieving carbon neutralization and carbon negative emission. However, most of the existing solid CO2 adsorbents have low adsorption capacity and are prone to photothermal desorption under light.

[0003] Therefore, it is urgent to provide a modified boron nitride material and a method for improving the carbon dioxide adsorption capacity of the modified boron nitride material to solve the above problems of the existing solid CO2 adsorbents. SUMMARY

[0004] In view of the problem of low adsorption capacity of most CO2 adsorbents in the prior art, the application provides a modified boron nitride material and a method for improving the carbon dioxide adsorption capacity of the modified boron nitride material. The modified boron nitride material provided by the application has high carbon dioxide adsorption capacity, and the method used can significantly improve the adsorption capacity of the modified boron nitride material.

[0005] In a first aspect, the application provides a modified boron nitride material, which is a boron nitride material doped with carbon elements and oxygen elements.

[0006] The content of oxygen elements in the modified boron nitride material is 28-32%, and the content of carbon elements is 12-18%.

[0007] Preferably, the content of carbon elements in the modified boron nitride material is 14-17.5%.

[0008] Preferably, the content of boron elements in the modified boron nitride material is 27-36%, preferably 27-31%; and / or

[0009] The content of nitrogen elements in the modified boron nitride material is 22-27%, preferably 23.5-26.5%.

[0010] Preferably, the raw materials for preparing the modified boron nitride material include boric acid and carbon-nitrogen compounds.

[0011] In a second aspect, the application provides a method for improving the carbon dioxide adsorption capacity of the modified boron nitride material of the first aspect, which comprises:

[0012] Irradiate the modified boron nitride material in a carbon dioxide adsorption process with ultraviolet light.

[0013] Preferably, the wavelength of the ultraviolet light is 200-330 nm.

[0014] Preferably, the light intensity of the ultraviolet light is 30 W.

[0015] Preferably, the time of the ultraviolet light irradiation is 5-120 min.

[0016] Preferably, the distance between the light source of the ultraviolet light and the modified boron nitride material is 5-20 cm.

[0017] Preferably, under the ultraviolet light irradiation condition, the carbon dioxide adsorption capacity of the modified boron nitride material is increased by 12.2-28.7% at 25℃ and 1 bar of CO2 partial pressure.

[0018] Compared with the prior art, the present application has at least the following beneficial effects:

[0019] The modified boron nitride material of the present application is a boron nitride material doped with carbon and oxygen elements, and has a large proportion of carbon and oxygen element doping and a large number of defect sites, and has a high carbon dioxide adsorption capacity.

[0020] The present application uses a modified boron nitride material as a CO2 adsorbent, and synchronously irradiates the modified boron nitride material in a CO2 adsorption process with ultraviolet light. The ultraviolet light induces excitation of the modified boron nitride material, and regulates the electronic structure and basic sites of the modified boron nitride material to enhance the binding strength of the modified boron nitride material and CO2, thereby improving the CO2 adsorption capacity of the modified boron nitride material.

[0021] The present application selects ultraviolet light with low thermal effect, which overcomes the defect that photothermal effect causes CO2 desorption in the past. This method not only does not cause CO2 desorption due to photothermal effect, resulting in a decrease in adsorption capacity, but also can excite the modified boron nitride material to produce more free electrons under ultraviolet light irradiation, so that the electron-donating ability (basic sites) of the adsorbent is enhanced, and a stronger interaction is produced with CO2 molecules, thereby significantly improving the CO2 adsorption capacity of the modified boron nitride material. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 is an X-ray diffraction pattern of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application;

[0024] Figure 2 is a Fourier transform infrared spectroscopy pattern of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application;

[0025] Figure 3 is an X-ray photoelectron spectroscopy pattern of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application;

[0026] Figure 4 is a solid ultraviolet-visible diffuse reflectance spectroscopy pattern of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application;

[0027] Figure 5 is a band gap calculation pattern of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application;

[0028] Figure 6 is a CO2 adsorption isotherm of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application without ultraviolet light irradiation;

[0029] Figure 7 is a CO2 adsorption isotherm of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application with ultraviolet light irradiation;

[0030] Figure 8 is a comparison graph of CO2 adsorption capacity of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application without ultraviolet light irradiation at 25℃ and CO2 partial pressure of 0.15 bar;

[0031] Figure 9 is a comparison graph of CO2 adsorption capacity of the adsorbent 1-4 (modified boron nitride material 1-4) provided by the present application with ultraviolet light irradiation at 25℃ and CO2 partial pressure of 1 bar;

[0032] Figure 10 is a scanning electron microscope pattern of the adsorbent 1 (modified boron nitride material 1) provided by the present application;

[0033] Figure 11 is a transmission electron microscope pattern of the adsorbent 1 (modified boron nitride material 1) provided by the present application;

[0034] Figure 12 is a high-resolution transmission electron microscope pattern of the adsorbent 1 (modified boron nitride material 1) provided by the present application;

[0035] Figure 13 is a corresponding X-ray elemental map of the adsorbent 1 (modified boron nitride material 1) provided by the present application;

[0036] Figure 14 This is a temperature-programmed desorption diagram of CO2- before and after ultraviolet lamp irradiation of the adsorbent 1 (modified boron nitride material 1) provided by the present invention.

[0037] Figure 15 This is the electron paramagnetic resonance spectrum of the adsorbent 1 (modified boron nitride material 1) provided by the present invention under in-situ high-pressure mercury lamp irradiation. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] In a first aspect, the present invention provides a modified boron nitride material, wherein the modified boron nitride material is a boron nitride material doped with carbon and oxygen elements;

[0040] The modified boron nitride material contains 28-32% oxygen (e.g., 28%, 28.5%, 28.74%, 29%, 29.5%, 30.36%, 30.5%, 31%, 31.8%, or 32%) and 12-18% carbon (e.g., 12%, 13%, 14%, 14.14%, 14.5%, 15.2%, 15.6%, 16%, 16.5%, 17%, or 18%).

[0041] The modified boron nitride material of the present invention is a boron nitride material doped with carbon and oxygen elements. The proportion of carbon and oxygen elements is relatively large, and it has a large number of defect sites, resulting in a high carbon dioxide adsorption capacity.

[0042] The modified boron nitride material of the present invention exhibits a CO2 adsorption capacity of 0.54–0.91 mmol / g at 25°C and 0.15 bar CO2 under no light conditions; and a CO2 adsorption capacity of 1.23–2.04 mmol / g at 25°C and 1 bar CO2.

[0043] According to some preferred embodiments, the carbon content in the modified boron nitride material is 14-17.5% (for example, it can be 14%, 14.14%, 14.5%, 15.2%, 15.6%, 16%, 16.5%, 17% or 17.5%).

[0044] According to some preferred embodiments, the boron content in the modified boron nitride material is 27-36% (e.g., 27%, 27.44%, 28%, 28.5%, 29%, 29.13%, 29.5%, 30%, 30.83%, 31%, 31.5%, 32%, 32.5%, 33%, 33.5%, 34%, 34.5%, 35%, 35.5%, or 36%), preferably 27-31% (e.g., 27%, 27.44%, 28%, 28.5%, 29%, 29.13%, 29.5%, 30%, 30.83%, or 31%); and / or

[0045] The nitrogen content in the modified boron nitride material is 22-27% (e.g., 22%, 22.5%, 23%, 23.87%, 24%, 24.87%, 25%, 25.5%, 26%, 26.3%, or 27%), preferably 23.5-26.5% (e.g., 23.5%, 23.87%, 24%, 24.87%, 25%, 25.5%, 26%, 26.3%, or 26.5%).

[0046] According to some preferred embodiments, the raw materials for preparing the modified boron nitride material include boric acid and carbon-nitrogen compounds; the carbon-nitrogen compounds are preferably one or more selected from urea, melamine, cyanuric acid, ethylenediamine, diethylamine, ethanolamine, oleylamine, polyethyleneimine, and diethylenetriamine.

[0047] In some specific embodiments of the present invention, the preparation method of the modified boron nitride material includes: adding a carbonitride compound to a boric acid solution and stirring to obtain a clear solution; wherein the mass ratio of boric acid to carbonitride compound is 1:(1-3); the stirring temperature is 80-95°C; the clear solution is heated to remove the solvent to obtain a white powder; wherein the heating temperature is 80-95°C, preferably 90°C, and the time is 15-24h; the white powder is subjected to high-temperature pyrolysis to obtain the modified boron nitride material; wherein the high-temperature pyrolysis is carried out in an inert gas atmosphere, with a heating rate of 1-10°C / min, to 800-1200°C and held for 4-8h; preferably, in an inert gas atmosphere, with a heating rate of 2°C / min, to 800°C and held for 6h. The inventors discovered that removing the solvent through heating can increase the oxygen content of modified boron nitride materials. Compared to other methods, heating a clear solution to produce a precipitate, filtering the precipitate, drying it, and then pyrolyzing it at high temperature to obtain boron nitride doped materials with higher oxygen content, the latter method yields a more efficient solution.

[0048] In a second aspect, the present invention provides a method for improving the carbon dioxide adsorption capacity of the modified boron nitride material described in the first aspect, the method comprising:

[0049] Using modified boron nitride as a carbon dioxide adsorbent, the modified boron nitride material undergoing the carbon dioxide adsorption process is irradiated with ultraviolet light.

[0050] This invention uses modified boron nitride material as a CO2 adsorbent. The modified boron nitride material undergoing CO2 adsorption is simultaneously irradiated with ultraviolet light. The modified boron nitride material is photo-induced excited by ultraviolet light, and the electronic structure and basic sites of the modified boron nitride material are regulated to enhance the binding strength between the modified boron nitride material and CO2, thereby improving the adsorption capacity of the modified boron nitride material for CO2.

[0051] This invention selects ultraviolet irradiation with a low thermal effect, overcoming the defect that photothermal effects can lead to CO2 desorption. This method not only avoids CO2 desorption due to photothermal effects and the resulting decrease in adsorption capacity, but also excites the modified boron nitride material to generate more free electrons under ultraviolet irradiation. This enhances the electron-donating ability (basic sites) of the adsorbent, resulting in a stronger interaction with CO2 molecules and significantly improving the CO2 adsorption capacity of the modified boron nitride material.

[0052] The modified boron nitride material of the present invention exhibits a CO2 adsorption capacity increase of 12.2% to 28.7% under ultraviolet irradiation at 25°C and 0.15 bar CO2, and a CO2 adsorption capacity increase of 12.5% ​​to 32.1% at 25°C and 1 bar CO2.

[0053] According to some preferred embodiments, the wavelength of the ultraviolet light is 200-330nm (for example, it can be 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm, 310nm, 320nm or 330nm).

[0054] According to some preferred embodiments, the intensity of the ultraviolet light is 30W.

[0055] According to some preferred embodiments, the ultraviolet irradiation time is 5 to 120 minutes (for example, it can be 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes or 120 minutes).

[0056] According to some preferred embodiments, the distance between the ultraviolet light source and the modified boron nitride material is 5 to 20 cm (for example, it can be 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 11 cm, 12 cm, 13 cm, 14 cm, 15 cm, 16 cm, 17 cm, 18 cm, 19 cm or 20 cm).

[0057] According to some preferred embodiments, under ultraviolet light irradiation at 25°C and a CO2 partial pressure of 1 bar, the carbon dioxide adsorption capacity of the modified boron nitride material is increased by 12.2% to 28.7%.

[0058] To more clearly illustrate the technical solution and advantages of the present invention, the present invention will be further described below in conjunction with embodiments.

[0059] Preparation of modified boron nitride materials:

[0060] S1: Take four 200mL beakers, numbered 1#, 2#, 3#, and 4#, add 1.5g of boric acid to each, and then add 150ml of deionized water to each of the four beakers. Place them on a heating and stirring table, heat to 60℃, and stir continuously at 400r / min until the solution is clear.

[0061] S2: According to a certain raw material mass ratio, add 4.5g, 3g, 1.5g and 0.5g of melamine to beakers 1-4 respectively, raise the temperature to 90℃, increase the rotation speed to 800r / min, and continue stirring until the mixture becomes clear.

[0062] S3: Next, place the 1-4# beakers containing the clarified mixture into an electric blast oven, set the temperature to 90℃, and heat for 15 hours to obtain a white solid. Remove the solid and grind it into powder.

[0063] S4: The obtained white powder 1-4# is loaded into a tube furnace, and after being purged with N2 atmosphere for a certain period of time, the pyrolysis step is started. Under the protective atmosphere of N2 with a continuous flow rate of 30 mL / min, the temperature of the tube furnace is heated to 800℃ at a heating rate of 2℃ / min for 6 hours. Then it is naturally cooled to room temperature. The pyrolysis products obtained from the white powder 1-4# are ground to obtain modified boron nitride material 1-4 (for simplicity, modified boron nitride material 1-4 is referred to as adsorbent 1-4 in the following text and the attached diagram of the specification).

[0064] The present invention performs X-ray diffraction experiments on the prepared adsorbents 1-4, such as... Figure 1As shown, adsorbents 1-4 exhibited two broad diffraction peaks near 26° and 43°, attributed to the (002) and (100) planes of h-BN, respectively. Simultaneously, it was observed that the diffraction peak intensity decreased and crystallinity decreased with increasing melamine content in the raw materials. It should be noted that... Figure 1 PDF#34-0421 is a standard XRD card for pure crystalline hexagonal boron nitride.

[0065] The Fourier transform infrared spectra of adsorbents 1-4 prepared in this invention are as follows: Figure 2 As shown, it is located at ~1398cm -1 The spectrum at this location originates from the in-plane BN stretching vibrations of h-BN, and its signal weakens accordingly with decreasing boric acid / melamine ratio. Furthermore, ~1080 cm⁻¹ -1 The peak at this point can be attributed to the absorption band of -BO, at approximately 1670 cm⁻¹. -1 A C=N absorption peak was detected nearby, at ~3209 cm⁻¹. -1 and ~3430cm -1 The broad absorption bands at these locations should be attributed to -OH and -NH2, respectively.

[0066] The X-ray photoelectron spectra of adsorbents 1-4 prepared in this invention are as follows: Figure 3 As shown, the elemental composition of the adsorbent powder includes C and O in addition to B and N, indicating that C and O are doped into boron nitride. The specific relative content of elements in adsorbents 1-4 is shown in Table 1.

[0067] The solid UV-Vis diffuse reflectance spectra of adsorbents 1-4 prepared in this invention are as follows: Figure 4 As shown, the results indicate that all adsorbent samples exhibit strong absorption in the 200–330 nm range. With increasing carbon content (melamine ratio), the light absorption edge of the adsorbent gradually red-shifts; simultaneously, according to… Figure 5 The bandgap calculation plot shows that the bandgap width of the adsorbent gradually decreases with increasing carbon content (melamine ratio). The estimated bandgap width of adsorbent 1 is 1.71 eV. Note: Bandgap is based on the Tauc relation (αhυ). 2 =A(hυ-E) g The values ​​are calculated from α, h, υ, A, and E. g These refer to the absorption coefficient, Planck constant, optical frequency, constant, and band gap of a semiconductor, respectively.

[0068] In this invention, CO2 adsorption isotherm tests were conducted on the prepared adsorbents 1-4 under conditions of 25℃ and 0-1 bar with and without ultraviolet light. Figures 6-7As shown, the CO2 adsorption capacity of each adsorbent before and after UV irradiation at CO2 partial pressures of 0.15 bar (typical CO2 partial pressure in flue gas) and 1 bar is compared. Figures 8-9 As shown in the figure. The results indicate that the carbon dioxide adsorption capacity of all adsorbents increased to some extent after ultraviolet (UV) irradiation. Adsorbent 1 showed the largest increase after UV irradiation, with its carbon dioxide adsorption capacity increasing from 0.53 mmol / g to 0.70 mmol / g at a partial pressure of 0.15 bar CO2, representing an increase of approximately 32%. At a partial pressure of 1 bar CO2, its carbon dioxide adsorption capacity increased from 1.29 mmol / g to 1.66 mmol / g, representing an increase of approximately 28%.

[0069] Table 1. Elemental content and adsorption capacity data of each adsorbent

[0070]

[0071] As shown above, this invention successfully obtained various modified boron nitride materials (adsorbents 1-4), and the modified boron nitride materials have a large carbon and oxygen doping ratio, exhibiting good ultraviolet and visible light absorption. The CO2 adsorption capacity of adsorbents 1-4 was significantly improved after ultraviolet irradiation, with an improvement rate greater than 12%. Among them, adsorbent 1 showed the most significant improvement in CO2 adsorption capacity, with an improvement rate of 32.1% under 25℃ and 0.15 bar CO2 conditions; and an improvement rate of 28.7% under 25℃ and 1 bar CO2 conditions.

[0072] Furthermore, the present invention also performed other characterizations on adsorbent 1, including scanning electron microscopy images (…). Figure 10 The morphology of adsorbent 1 shows a typical micron-sized banded morphology obtained from pyrolysis at high temperatures; transmission electron microscopy (TEM) images ( Figure 11 The image shows that adsorbent 1 is composed of many stacked ribbons and multilayered graphene-like nanosheets; high-resolution transmission electron microscopy image ( Figure 12 The microstructure of the worm-like microporous network can be observed, and a diffraction pattern similar to that of an amorphous state can be obtained by performing a local (circled area in the figure) Fast Fourier Transform. Figure 12 (Inset in the upper right corner). The corresponding X-ray elemental spectrum of adsorbent 1 (…). Figure 13 The results show that elements B, C, N, and O are uniformly distributed in the selected area, and adsorbent 1 has residual carbon and abundant oxygen-containing functional groups.

[0073] This invention conducted CO2-programmed desorption tests on adsorbent 1 before and after ultraviolet light irradiation. The tests were performed on a chemisorption analyzer equipped with a quartz tube reactor and a thermal conductivity detector. Specifically:

[0074] Dark environment test: 50 mg of adsorbent 1 was degassed in nitrogen (30 mL / min) at 200 °C for 1 hour, cooled to room temperature (25 °C), and then high-purity carbon dioxide (40 mL / min) was introduced. Adsorption was carried out for 2 hours to reach adsorption equilibrium (the adsorbent was in the dark during the adsorption process); then adsorbent 1 was heated to 800 °C in nitrogen (30 mL / min) at a heating rate of 10 °C / min and held for 10 minutes. The desorbed CO2 was then detected using a thermal conductivity detector.

[0075] UV irradiation environment test: 50 mg of adsorbent was degassed in nitrogen (30 mL / min) at 200 °C for 1 hour. After cooling to room temperature (25 °C), high-purity carbon dioxide (40 mL / min) was introduced, and adsorption was carried out for 2 hours to reach adsorption equilibrium (during the adsorption process, the adsorbent was always irradiated under 320 nm UV light with an intensity of 30 W, and the distance between the light source and the adsorbent was approximately 10 cm). Then, the adsorbent was heated to 800 °C in nitrogen (30 mL / min) at a heating rate of 10 °C / min and held for 10 minutes. The desorbed CO2 was then detected using a thermal conductivity detector.

[0076] CO2- desorption of adsorbent 1 before and after UV irradiation by temperature program: Figure 14 As shown, the desorption peak near 49℃ can be attributed to physical adsorption caused by the specific surface area. The desorption peak signal at higher temperatures shows an inflection point at ~230℃, and the desorption peak signal between ~100-230℃ is attributed to the adsorption of -OH and -NH2 groups. The basic center at higher temperatures is generated by structural defects. Specifically, under the initial conditions, the desorption peak of adsorbent 1 at 360.8℃ should be caused by a large number of defects generated by carbon and oxygen doping. Because defect doping can generate the necessary negative charge on BCN, the BCN with the necessary negative charge can induce charge-induced chemisorption, thereby enhancing the binding of CO2 to the adsorbent surface. After ultraviolet irradiation, the desorption peak of the adsorbent shifts to higher temperatures (from 360.8℃ to 410.9℃), indicating that ultraviolet irradiation enhances the binding strength of CO2 to the adsorbent.

[0077] The present invention also conducted in-situ electron paramagnetic resonance spectroscopy tests on adsorbent 1 under high-pressure mercury lamp irradiation, and the test results are as follows: Figure 15(The inset shows a magnified view of the signal.) The results indicate that the adsorbent detected a strong electron paramagnetic resonance (EPR) signal at a magnetic field strength of approximately 343.4 mT. The calculated g value is approximately 2.003, which is symmetric, indicating that the g value corresponds to isotropic homogeneous free electron species. With prolonged light irradiation time, the EPR signal of the adsorbent increased. When the adsorbent was continuously irradiated with high-pressure mercury light for 0.5 minutes and 60 minutes, the EPR signal intensity increased by approximately 10% and 16%, respectively. This demonstrates that irradiation of the adsorbent leads to the accumulation of free electrons over time, but this process is not linear; the accumulation of free electrons slows down over time. The signal enhancement is due to the excitation of more free electrons in the adsorbent under light irradiation.

[0078] This invention conducted Hall effect tests on adsorbent 1 before and after ultraviolet (UV) irradiation. Specifically, after testing under dark conditions, the adsorbent was irradiated under a UV lamp for 2 hours, and the Hall effect was tested again approximately 2 minutes after the lamp was turned off. The Hall effect test allows us to further quantitatively understand the change in carrier concentration in the adsorbent before and after UV irradiation. As shown in Table 2, a negative Hall coefficient confirms that the adsorbent is an n-type semiconductor material, where electrons are the majority carriers. After UV irradiation, the resistivity of the adsorbent decreased significantly, and the carrier concentration decreased from 4.80 × 10⁻⁶. 20 / cm 3 Increased to 5.42 × 10 20 / cm 3 The carrier concentration increased by about 12.9%, which is sufficient to prove that ultraviolet light irradiation of the adsorbent can generate more free electrons, enhance the electron-donating ability of the material, and strengthen the interaction with CO2.

[0079] CO2 desorption tests before and after UV irradiation revealed that the adsorbent's binding force to CO2 was enhanced after UV irradiation. Electron paramagnetic resonance spectroscopy under in-situ high-pressure mercury lamp irradiation showed that the number of free electrons excited by the BCN material gradually increased with increasing irradiation time, resulting in a stronger adsorption effect on CO2. The CO2 adsorption isotherms of a series of adsorbent samples before and after UV irradiation were tested using a physical adsorption instrument within the range of 0-1 bar. The results showed that the adsorption capacity of all adsorbent samples for CO2 was significantly improved after UV irradiation across the entire partial pressure range.

[0080] Table 2. Hall effect test data of adsorbent 1 before and after irradiation with 320nm ultraviolet light.

[0081]

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the carbon dioxide adsorption capacity of modified boron nitride materials, characterized in that, The method includes: Using modified boron nitride as a carbon dioxide adsorbent, the modified boron nitride material undergoing the carbon dioxide adsorption process is irradiated with ultraviolet light; the modified boron nitride material is a boron nitride material doped with carbon and oxygen elements; the oxygen content in the modified boron nitride material is 28-32%, and the carbon content is 12-18%; The wavelength of the ultraviolet light is 200~330nm; under ultraviolet light irradiation conditions, at 25℃ and a partial pressure of CO2 of 1 bar, the carbon dioxide adsorption capacity of the modified boron nitride material is increased by 12.2~28.7%.

2. The method according to claim 1, characterized in that, The carbon content is 14-17.5%.

3. The method according to claim 1, characterized in that, The modified boron nitride material contains 27-36% boron. The modified boron nitride material contains 22-27% nitrogen.

4. The method according to claim 3, characterized in that, The modified boron nitride material contains 27-31% boron. The modified boron nitride material contains 23.5% to 26.5% nitrogen.

5. The method according to claim 1, characterized in that, The raw materials for preparing the modified boron nitride material include boric acid and carbon-nitrogen compounds.

6. The method according to claim 1, characterized in that, The intensity of the ultraviolet light is 30W.

7. The method according to claim 1, characterized in that, The duration of ultraviolet light irradiation is 5 to 120 minutes.

8. The method according to claim 1, characterized in that, The distance between the ultraviolet light source and the modified boron nitride material is 5~20cm.

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