Electricity-loaded adsorbent for direct air trapping as well as preparation method and application of electricity-loaded adsorbent

Abstract

The invention relates to the technical field of carbon dioxide adsorption, in particular to an electricity-loaded adsorbent for direct air trapping and a preparation method and application thereof.The preparation method comprises the steps that activated carbon cloth is subjected to first activation treatment, and porous structure carbon cloth is obtained; placing the porous structure carbon cloth in a three-electrode system of a caustic alkali solution, and carrying out charging treatment to obtain an electricity-loaded adsorbent precursor; and carrying out second activation treatment on the electricity-loaded adsorbent precursor to obtain the electricity-loaded adsorbent. In the charging process, hydroxyl ions are accumulated in pores of the activated carbon cloth electrode, so that the electricity-loaded adsorbent is prepared; the ions accumulated in the activated carbon cloth can be used as active sites during CO2 adsorption, so that the capture efficiency is effectively improved, and the maximum adsorption capacity is achieved; moreover, after adsorption, voltage can be directly applied to the two ends of the electricity-loaded adsorbent, desorption of CO2 is achieved through the generated Joule heating effect, and the regeneration capacity of the adsorbent is achieved.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide adsorption technology, and more particularly to a charged adsorbent for direct air capture, its preparation method, and its application. Background Technology

[0002] Reducing greenhouse gas emissions and restoring atmospheric CO2 levels to pre-industrial levels are key steps in achieving net-zero emissions and curbing climate change. Therefore, improving adsorbent performance for efficient atmospheric CO2 capture is crucial, particularly the development of low-cost, regenerable materials suitable for cryogenic conditions.

[0003] However, existing adsorbents for capturing carbon dioxide suffer from problems such as complex preparation processes, high costs, insufficient carbon dioxide adsorption capacity, and inability to be regenerated.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide an electrostatic adsorbent for direct air capture, its preparation method and application, aiming to solve the problems of insufficient carbon dioxide adsorption capacity and inability to regenerate existing adsorbents.

[0006] The technical solution of the present invention is as follows: A method for preparing an electrophoretic adsorbent for direct air capture includes the following steps: The activated carbon cloth is subjected to a first activation treatment to obtain a porous carbon cloth. The porous carbon structure is arranged in a three-electrode system of caustic alkali solution and charged to obtain a precursor of charged adsorbent. The precursor of the charged adsorbent is subjected to a second activation treatment to obtain the charged adsorbent.

[0007] The method for preparing the charged adsorbent for direct air capture, wherein the activated carbon cloth is selected from one of Kynol's ACC-5092-11, Sutong Carbon Fiber Co., Ltd.'s STC-1000-70G, Sutong Carbon Fiber Co., Ltd.'s STC-1000-100G, Sutong Carbon Fiber Co., Ltd.'s STC-1300, and Sutong Carbon Fiber Co., Ltd.'s STC-1800.

[0008] The method for preparing the charged adsorbent for direct air capture, wherein the temperature of the first activation treatment is 200℃-800℃ and the time of the first activation treatment is 10min-100min.

[0009] The method for preparing the charged adsorbent for direct air capture, wherein the caustic alkali solution is selected from at least one of potassium hydroxide solution and sodium hydroxide solution.

[0010] The method for preparing the charged adsorbent for direct air capture includes a three-electrode system comprising a reference electrode, a counter electrode, and a working electrode; the porous carbon cloth serves as the working electrode.

[0011] The method for preparing the charged adsorbent for direct air capture, wherein the reference electrode is selected from one of Hg / HgO electrode, Hg / Hg2Cl2 electrode, and Ag / AgCl electrode; and the counter electrode is selected from one of platinum wire, platinum sheet, platinum mesh, graphite, glassy carbon, and carbon cloth.

[0012] The method for preparing the charged adsorbent for direct air capture, wherein the voltage of the charging treatment is 1V-2V.

[0013] The method for preparing the charged adsorbent for direct air capture, wherein the temperature of the second activation treatment is 90℃-120℃ and the time of the second activation treatment is 1h-12h.

[0014] An electrophoretic adsorbent for direct air capture is prepared using the method for preparing the electrophoretic adsorbent for direct air capture.

[0015] Application of a charged adsorbent for direct air capture in carbon dioxide adsorption.

[0016] Beneficial effects: This invention provides an charged adsorbent for direct air capture, its preparation method, and its application. The preparation method includes the following steps: performing a first activation treatment on activated carbon cloth to obtain a porous carbon cloth; arranging the porous carbon cloth in a three-electrode system of caustic alkali solution for charging treatment to obtain a charged adsorbent precursor; and performing a second activation treatment on the charged adsorbent precursor to obtain the charged adsorbent. This invention prepares a charged adsorbent based on the charging mechanism of an electrochemical energy storage device. Utilizing a three-electrode system, when a voltage lower than the decomposition voltage of the electrolyte solution is applied, positive and negative ions in the electrolyte rapidly move to the electrode surface under the influence of an electric field, forming a tight double-layer charge layer. Under the influence of an external voltage, some electrons flow from the porous carbon cloth to the counter electrode, and negative ions (such as hydroxide ions) in the electrolyte are adsorbed into the pores of the porous carbon cloth. This method can load hydroxide ions onto the surface of the porous carbon cloth, and after a second activation treatment, a charged adsorbent can be prepared. In other words, during the charging process, hydroxide ions accumulate in the pores of the porous carbon cloth serving as the electrode, thereby preparing the charged adsorbent. These ions accumulated inside the porous carbon cloth can act as active sites for CO2 adsorption, effectively improving the capture efficiency and achieving maximum adsorption capacity. Furthermore, after adsorption, CO2 desorption can be achieved by directly applying a voltage across the charged adsorbent, utilizing the resulting Joule heating effect, thus realizing the adsorbent's regeneration capability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the preparation process of a charged adsorbent for direct air capture according to the present invention; Figure 2 This is a schematic diagram of charging a porous carbon cloth in 6 M KOH using a three-electrode electrolytic cell, as shown in Example 1. Figure 3 The charging current-time curve of ACC-300-OH at constant potential; Figure 4 Cyclic voltammetry curves of ACC-300-OH and 70G-OH in 6M KOH; Figure 5 This is a graph showing the change in outlet CO2 concentration with time and material temperature, as measured by the CO2 sensor after the ACC-300-OH adsorption process is completed. Figure 6 Adsorption capacity data of charged adsorbents prepared for activated carbon cloth with different structures; Figure 7 The N2 adsorption isotherms are shown for eight samples of charged adsorbents. Figure 8 A graph showing the relationship between the conductivity and charge capacity per unit mass of different activated carbon cloths; Figure 9The graph shows the relationship between the charge capacity per unit mass and the CO2 adsorption capacity of activated carbon cloths with different structures. Figure 10 The graph shows the relationship between the average pore size and adsorption capacity of activated carbon cloth with different structures after loading. Figure 11 This is a graph showing the relationship between the decrease in specific surface area before and after loading and the charge capacity per unit mass. Figure 12 This is a graph showing the relationship between CO2 adsorption capacity and the specific surface area of ​​activated carbon cloth. Detailed Implementation

[0018] This invention provides a charged adsorbent for direct air capture, its preparation method, and its application. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0020] like Figure 1 As shown, the present invention provides a method for preparing a charged adsorbent for direct air capture, comprising the following steps: Step S10: Perform a first activation treatment on the activated carbon cloth to obtain a porous carbon cloth; Step S20: The porous carbon structure is arranged in a three-electrode system of caustic alkali solution for charging treatment to obtain a charged adsorbent precursor; Step S30: Perform a second activation treatment on the charged adsorbent precursor to obtain the charged adsorbent.

[0021] In this embodiment, a charged adsorbent is prepared based on the charging mechanism of an electrochemical energy storage device. A three-electrode system is used, with a caustic alkali solution as the electrolyte. When a voltage lower than the decomposition voltage of the electrolyte solution is applied, positive and negative ions in the electrolyte rapidly move to the electrode surface under the influence of the electric field, forming a dense electric double layer. Under the influence of the external voltage, some electrons flow from the porous carbon cloth to the counter electrode, and negative ions (such as hydroxide ions) in the electrolyte are adsorbed into the pores of the porous carbon cloth. This method can be used to load hydroxide ions onto the porous carbon cloth. The surface is then subjected to a second activation treatment to prepare an electrostatic adsorbent. In other words, during the charging process, hydroxide ions accumulate in the pores of the porous carbon cloth that serves as the electrode. After the second activation treatment, an electrostatic adsorbent is prepared. These ions accumulated inside the porous carbon cloth can serve as active sites for CO2 adsorption, effectively improving the capture efficiency and achieving the maximum adsorption capacity. Furthermore, after adsorption, CO2 desorption can be achieved by directly applying a voltage across the two ends of the electrostatic adsorbent and utilizing the generated Joule heating effect, thus realizing the regeneration capability of the electrostatic adsorbent.

[0022] Specifically, the charged adsorbent prepared by the above method can adsorb CO2 at room temperature (e.g., 25°C) and release CO2 at a relatively low temperature range (90-120°C).

[0023] In some embodiments, the activated carbon cloth is selected from, but not limited to, one of Kynol's ACC-5092-11, Sutong Carbon Fiber Co., Ltd.'s STC-1000-70G, Sutong Carbon Fiber Co., Ltd.'s STC-1000-100G, Sutong Carbon Fiber Co., Ltd.'s STC-1300, and Sutong Carbon Fiber Co., Ltd.'s STC-1800. The aforementioned carbon cloth has a rich porous structure and good electrical conductivity and hydrophilicity, which can improve the loading effect of -OH groups.

[0024] In some embodiments, before step S10, the method further includes cleaning the activated carbon cloth with deionized water to remove dust and other impurities.

[0025] In some embodiments, the temperature of the first activation treatment is 200℃-800℃, and the time of the first activation treatment is 10min-100min. By performing the first activation treatment on the activated carbon cloth, volatile substances in the activated carbon cloth can be removed, resulting in activated carbon cloth with a rich porous structure; furthermore, by controlling the temperature and time of the activation treatment, porous carbon cloth with different pore structures and specific surface areas can be obtained.

[0026] In a preferred embodiment, the temperature of the first activation treatment is 300°C, 500°C, or 700°C, and the time of the first activation treatment is 60 minutes.

[0027] In some embodiments, the caustic alkali solution is selected from, but is not limited to, at least one of potassium hydroxide and sodium hydroxide. Potassium hydroxide or sodium hydroxide is used as the charged adsorbent to provide hydroxide ions, and a charging mechanism is used to load it onto the surface of the porous carbon cloth.

[0028] In some embodiments, the three-electrode system includes a reference electrode, a counter electrode, and a working electrode; the porous carbon cloth serves as the working electrode.

[0029] In some embodiments, the reference electrode is selected from, but is not limited to, one of Hg / HgO electrode, Hg / Hg2Cl2 electrode, and Ag / AgCl electrode; the counter electrode is selected from, but is not limited to, one of platinum wire, platinum sheet, platinum mesh, graphite, glassy carbon, and carbon cloth.

[0030] In some embodiments, the voltage of the charging process is 1V-2V.

[0031] In some embodiments, the temperature of the second activation treatment is 90℃-120℃, and the activation time is 1h-12h. The second activation treatment allows -OH groups to be loaded onto the carbon cloth, and also dries the charged adsorbent, removing moisture.

[0032] In some embodiments, after obtaining the charged adsorbent precursor and before performing the second activation treatment, the method further includes: using non-conductive tweezers (such as plastic tweezers) to remove the charged adsorbent precursor from the caustic alkali solution and rinsing it with deionized water to remove residual caustic alkali solution.

[0033] In addition, the present invention also provides an charged adsorbent for direct air capture, which is prepared by the method for preparing the charged adsorbent for direct air capture.

[0034] In this embodiment, the charged adsorbent prepared by the above method can adsorb CO2 at room temperature (e.g., 25°C) and release CO2 at a relatively low temperature range (90-120°C).

[0035] In addition, the present invention also provides the application of a charged adsorbent for direct air capture in carbon dioxide adsorption.

[0036] In this embodiment, the charged adsorbent is applied to carbon dioxide adsorption, which can adsorb CO2 at room temperature (e.g., 25°C) and release CO2 at a relatively low temperature range (90-120°C).

[0037] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0038] Example 1 1) Material preparation Activated carbon cloth ACC-5092-11 (denoted as ACC-10) was purchased from Kynol. ACC-5092-11 was activated at different temperatures, specifically at 300℃, 500℃, and 700℃ for 1 hour, to obtain ACC-10-300, ACC-10-500, and ACC-10-700. Activated carbon cloths STC-1000-70G, STC-1000-100G, STC-1300, and STC-1800 were purchased from Sutong Carbon Fiber Co., Ltd. (Jiangsu, China). These eight activated carbon cloths had different electrical conductivity, specific surface area, and average pore size. Before using these activated carbon cloths, they were all placed in a vacuum drying oven and activated at 100℃ for 1 hour. Potassium hydroxide (99%) was purchased from Sigma Aldrich. All chemicals were of analytical grade and could be used directly without further purification. N2 (99.99%) and 400ppm CO2 (with nitrogen as the balance gas) were both purchased from GAC Gas Co., Ltd. (Guangzhou, China).

[0039] It should be noted that STC-1000-70G, STC-1000-100G, STC-1300 and STC-1800 have different electrical conductivities, specific surface areas and average pore sizes, therefore, they are not activated in this embodiment.

[0040] 2) Preparation of Electrophoretic Adsorbent A self-made three-electrode electrolytic cell system was used in the preparation process. The experimental setup is as follows: Figure 2As shown, the main components include: an electrochemical workstation (CHI660e, CH Instruments, China), an electrolytic cell, a Hg / HgO (in 0.1M KOH) reference electrode, a platinum sheet electrode (LEDONLAB), and a platinum wire electrode (CHI115, YUECHI, ​​China). Platinum wires were repeatedly threaded through the activated carbon cloth and connected to the positive terminal of the power supply. The platinum sheet electrode was connected to the negative terminal. Chronoamperometry (CA) was used to charge STC-1000-70G, STC-1000-100G, STC-1300, STC-1800, ACC-10, ACC-10-300, ACC-10-500, and ACC-10-700, respectively. Eight types of activated carbon were arranged in 40 mL of 6M KOH aqueous solution and charged at a constant potential for 4 hours. After charging, the activated carbon cloth was removed using plastic tweezers and rinsed on both sides with 500 mL of deionized water for a total of 5 minutes to thoroughly remove any residual KOH solution. The rinsed activated carbon was then placed in a vacuum drying oven and dried at 75°C for 24 hours to remove excess moisture. Finally, the dried activated carbon cloth was placed in a vacuum drying oven at 120°C for 12 hours for activation, yielding 70G-OH, 100G-OH, 1300-OH, 1800-OH, ACC-10-OH, ACC-300-OH, ACC-500-OH, and ACC-700-OH, respectively.

[0041] in, Figure 3 The charging current-time curve of ACC-10-OH at a constant potential is shown. During the charging process, the presence of capacitive current and Faraday current was observed, indicating that hydroxides are accumulated through double layer formation and oxidation of surface functional groups.

[0042] Meanwhile, to determine the charging potential of different activated carbon cloths, cyclic voltammetry was used. Different activated carbon cloths were scanned in 6M KOH solution at a scan rate of 20 mV / s to obtain the charging potential of the materials. Figure 4 It shows ACC-10-OH ( Figure 4 a) and 70G-OH ( Figure 4The cyclic voltammetry curves in section b) show that the double-layer charging initiation potentials of ACC-10-OH and 70G-OH are 0.565V and 0.715V, respectively. Therefore, these two values ​​are taken as the charging potentials of the corresponding materials. Using this method, the charging potentials of ACC-10-OH, ACC-500-OH, and ACC-700-OH were measured to be 0.565V vs SHE; the charging potential of 100G-OH was 0.715V vs SHE; the charging potential of 1800-OH was 0.5V vs SHE; and the charging potential of 1300-OH was 1.165V vs SHE.

[0043] The different charged adsorbents prepared above were characterized by measuring the N2 adsorption-desorption isotherm at 77 K using a surface area and micropore analyzer (BSDPM2, Best Instruments, China). The following parameters were calculated based on the N2 adsorption-desorption isotherm data: (1) The pore size distribution of the samples was determined by the Dubinin-Astakhov (DR) micropore method and the NLDFT pore size and pore volume method, respectively; (2) The porosity of the samples was characterized by a fully automated true density and porosity analyzer (BSD-TD-K, Best Instruments, China); (3) The specific surface area of ​​the samples was obtained by the BET multi-point specific surface area method. The details are as follows: 1) CO2 adsorption performance test The CO2 adsorption performance of all adsorbents was measured in the adsorption chamber. Activated carbon cloth was assisted in heating by a polyimide heating element placed in the adsorption chamber. Thermocouples were used to control the desorption temperature of the adsorbents, and gas chromatography (GC9790PLUS, Fuli Instruments, China) was used to measure the adsorption and desorption of CO2. A CO2 sensor (N-CO2, Songbai Gas Sensor, China) was used to record real-time changes in CO2 concentration.

[0044] Before the CO2 adsorption experiment, the charged adsorbent needs to undergo a rigorous pretreatment process. Specifically, activated carbon cloth (1.5cm × 2cm) loaded with hydroxide ions is placed in the adsorption chamber, heated to 110°C, and purged with N2 at 100ml / min for 60 minutes to thoroughly remove any CO2 and moisture that may be adsorbed on the activated carbon cloth. Subsequently, the temperature is lowered to 30°C, and the inlet gas is switched to 400ppm CO2 at 60ml / min (with nitrogen as the equilibrium gas). Adsorption continues for 20 minutes until adsorption equilibrium is reached, during which the adsorption curve is recorded. After the adsorption process is completed, the activated carbon cloth is heated to 120°C for desorption, and the desorption curve is recorded. Then, the next adsorption-desorption cycle is performed to complete the cycle performance test.

[0045] in, Figure 5The graph shows the change in outlet CO2 concentration as a function of time and material temperature, as measured by the CO2 sensor, after the adsorption process of ACC-300-OH. In this experiment, the electrophoretic adsorbent was heated with a voltage of 10V, and the material temperature was slowly increased to about 100℃ over 300s and maintained at this temperature for 100s. As can be seen from the graph, when the material temperature rises to about 80℃, CO2 begins to desorb from the material, at which point the outlet CO2 concentration rises sharply, reaching a peak of 2500ppm. After 200 seconds, the desorption process is basically complete, and the outlet CO2 concentration gradually returns to the ambient concentration. The area represented by the blue region in the graph is the amount of desorption by the material.

[0046] The adsorption capacity of the charged adsorbent after loading was then tested (inlet CO2 concentration was 400 ppm). Figure 6 The adsorption capacity of eight different activated carbon cloths with varying structures is shown in the figure. As can be seen from the figure, ACC-300-OH exhibits the best adsorption performance at a CO2 concentration of 400 ppm, with an adsorption capacity as high as 0.213 mmol / g. It is noteworthy that the overall adsorption performance of the STC series samples is worse than that of the AC series samples; this difference is mainly attributed to the smaller average pore size of the AC series samples. To further analyze the performance characteristics of these materials, Table 1 summarizes the charge capacity per unit mass, average pore size after loading, pore volume after loading, porosity, and specific surface area before and after loading for the eight different activated carbon cloths.

[0047] Table 1. Characteristic parameters of activated carbon cloths with different structures

[0048] Note: a represents the charge capacity per unit mass; b represents the specific surface area before loading; c represents the specific surface area after loading.

[0049] Figure 7 The N2 adsorption isotherms of eight charged adsorbent samples are presented. In the lower adsorption pressure range (P / P0 < 1), the isotherms exhibit a nearly vertical, steep adsorption trend, and no obvious hysteresis loop was observed in the pressure range of 0.2 to 0.99. This characteristic indicates that all activated carbon cloth samples possess excellent chemisorption selectivity; they do not chemically react with N2 molecules. Furthermore, these samples are rich in microporous structures, while the content of mesopores is negligible.

[0050] 2) Charge capacity per unit mass The charge capacity per unit mass can be expressed by the formula calculate: Where Q represents the total charge obtained by integrating the chronocurrent curve, and m represents the mass of the activated carbon cloth. Figure 8The relationship between the conductivity and charge capacity per unit mass of different activated carbon cloths is shown, with the charge capacity per unit mass exhibiting a significant increasing trend as the conductivity increases. This is because the higher the conductivity of the material, the greater the current flowing inside it, and thus the total charge calculated by integrating the chronoamperometry curve within the same time period also increases accordingly.

[0051] Figure 9 The relationship between the charge capacity per unit mass and CO2 adsorption capacity of activated carbon cloths with different structures is shown. As can be seen from the figure, the CO2 adsorption capacity increases with increasing charge capacity per unit mass, and this trend is verified by linear fitting, with R0... 2 The value is as high as 0.92, which fully demonstrates the strong correlation between the two. Specifically, when the charge capacity per unit mass increases from 622 C / g to 1173 C / g, the CO2 adsorption capacity also increases significantly from 0.056 mmol / g to 0.213 mmol / g. This change process intuitively demonstrates the positive impact of the increase in charge capacity on CO2 adsorption performance.

[0052] The greater the charge capacity per unit mass of activated carbon cloth, the more charge the material stores through the electric double layer. Therefore, more anions (especially hydroxide ions) are loaded from the solution onto the surface of the activated carbon cloth. At extremely low CO2 partial pressures (i.e., an inlet CO2 concentration of 400 ppm), these hydroxide ions react chemically with CO2, thus achieving highly efficient CO2 capture.

[0053] 3) Average aperture The relationship between the average pore size and adsorption capacity of activated carbon cloth with different structures is as follows: Figure 10 As shown, the average pore size of all eight activated carbon cloths with different structures is less than 2 nm, indicating that the activated carbon cloths are all microporous materials. Furthermore, as the average pore size of the activated carbon cloths increased from 0.933 nm to 1.119 nm, the CO2 adsorption capacity significantly decreased from 0.213 mmol / g to 0.056 mmol / g. Figure 12 Linear fitting analysis was performed on the data points in the dataset, and the resulting R0 was obtained. 2 The value is 0.88, which indicates that the adsorption capacity increases as the average pore size of the activated carbon cloth decreases, meaning that the smaller the pore size, the greater the CO2 adsorption potential.

[0054] 4) Specific surface area The specific surface area of ​​activated carbon cloths with different structures decreased to varying degrees after loading with hydroxide ions. Specifically, the specific surface area of ​​the STC series activated carbon cloths decreased relatively little, with a reduction of less than 100 μm² before and after loading. 2Within / g; in contrast, the specific surface area of ​​AC series activated carbon cloth decreased more significantly, approaching 25% of the original value, with a reduction of more than 200m² in specific surface area before and after loading. 2 / g. For example... Figure 11 As shown, there is a high linear correlation between the decrease in specific surface area before and after loading and the charge capacity per unit mass, and the R-squared value of the linear fit is [value missing]. 2 The value is as high as 0.93, indicating that the larger the charge capacity per unit mass, the greater the decrease in specific surface area before and after loading. Figure 12 The linear fitting results of the specific surface area and CO2 adsorption capacity of activated carbon cloth before and after loading are presented. The results show that the correlation coefficient between the specific surface area before loading and the CO2 adsorption capacity is only 0.067, and the correlation coefficient between the specific surface area after loading and the CO2 adsorption capacity is only 0.304. Both values ​​indicate that the fitting effect is not ideal. Therefore, although the specific surface area of ​​activated carbon cloth decreases before and after loading, there is no direct correlation between CO2 adsorption performance and specific surface area.

[0055] Based on the above characterization, the main conclusions are as follows: 1) The higher the electrical conductivity of the material, the greater its charge capacity per unit mass, resulting in superior adsorption performance. This is attributed to the efficient accumulation of hydroxide ions on the surface of the activated carbon cloth. Specifically, as the charge capacity per unit mass increased from 622 C / g to 1173 C / g, the CO2 adsorption capacity increased from 0.056 mmol / g to 0.213 mmol / g. Furthermore, the increase in charge capacity per unit mass also led to a significant decrease in the specific surface area of ​​the material before and after hydroxide loading.

[0056] 2) The average pore size also significantly affects the adsorption performance of the material. When the average pore size of the activated carbon cloth increased from 0.933 nm to 1.119 nm, the CO2 adsorption capacity decreased significantly from 0.213 mmol / g to 0.056 mmol / g. The adsorption capacity increased with decreasing average pore size of the activated carbon cloth, indicating that smaller pore sizes have greater CO2 adsorption potential. Microporous materials exhibit superior adsorption capacity in this respect.

[0057] In summary, the present invention provides an charged adsorbent for direct air capture, its preparation method, and its application. The preparation method includes the following steps: performing a first activation treatment on activated carbon cloth to obtain a porous carbon cloth; arranging the porous carbon cloth in a three-electrode system of caustic alkali solution for charging treatment to obtain a charged adsorbent precursor; and performing a second activation treatment on the charged adsorbent precursor to obtain the charged adsorbent. This invention prepares a charged adsorbent based on the charging mechanism of an electrochemical energy storage device. Utilizing a three-electrode system, when a voltage lower than the decomposition voltage of the electrolyte solution is applied, positive and negative ions in the electrolyte rapidly move to the electrode surface under the influence of an electric field, forming a tight double-layer charge layer. Under the influence of an external voltage, some electrons flow from the activated carbon cloth to the counter electrode, and negative ions (such as hydroxide ions) in the electrolyte are adsorbed into the pores of the activated carbon cloth. This method allows hydroxide ions to be loaded onto the surface of the activated carbon cloth to prepare the charged adsorbent. In other words, during the charging process, hydroxide ions accumulate in the pores of the activated carbon cloth electrode, thereby preparing the charged adsorbent. These ions accumulated inside the activated carbon cloth can serve as active sites for CO2 adsorption, effectively improving the capture efficiency and achieving maximum adsorption capacity. Furthermore, after adsorption, CO2 desorption can be achieved by directly applying a voltage across the charged adsorbent, utilizing the resulting Joule heating effect, thus realizing the adsorbent's regeneration capability.

[0058] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for the preparation of a charge carrying adsorbent for direct air capture, characterized in that, The method comprises the steps of: carrying out a first activation treatment on the activated carbon cloth to obtain a porous structure carbon cloth; placing the porous structure carbon cloth in a three-electrode system of a caustic alkali solution to carry out a charging treatment to obtain an electric adsorbent carrier precursor; carrying out a second activation treatment on the electric adsorbent carrier precursor to obtain an electric adsorbent carrier.

2. The method of claim 1, wherein the method further comprises: The activated carbon cloth is selected from one of ACC-5092-11 of Kynol Company, STC-1000-70G of Sutong Carbon Fiber Co., Ltd., STC-1000-100G of Sutong Carbon Fiber Co., Ltd., STC-1300 of Sutong Carbon Fiber Co., Ltd., and STC-1800 of Sutong Carbon Fiber Co., Ltd.

3. The method of claim 1, wherein the method further comprises, The temperature of the first activation treatment is 200-800℃, and the time of the first activation treatment is 10-100 min.

4. The method of claim 1, wherein the method further comprises, The caustic alkali solution is at least one selected from a potassium hydroxide solution and a sodium hydroxide solution.

5. The method of claim 1, wherein the method further comprises: The three-electrode system comprises a reference electrode, a counter electrode and a working electrode, and the porous structure carbon cloth is used as the working electrode.

6. The method of claim 5, wherein the method further comprises, The reference electrode is selected from one of a Hg / HgO electrode, a Hg / Hg2Cl2 electrode and an Ag / AgCl electrode, and the counter electrode is selected from one of a platinum wire, a platinum sheet, a platinum mesh, graphite, glassy carbon and carbon cloth.

7. The method of claim 1, wherein the method further comprises, The voltage of the charging treatment is 1-2 V.

8. The method of claim 1, wherein the method further comprises, The temperature of the second activation treatment is 90-120℃, and the time of the second activation treatment is 1-12 h.

9. A charge carrying adsorbent for direct air capture, characterized in that, The method for preparing an electric adsorbent carrier for direct air capture is prepared by any one of claims 1-8.

10. Use of the electric adsorbent carrier for direct air capture according to claim 9 in carbon dioxide adsorption.

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