Modified activated carbon for xenon adsorption and preparation method thereof

Abstract

The invention provides modified activated carbon for xenon adsorption. The BET (Brunauer, Emmett and Teller) specific surface area of the modified activated carbon is 1000m / g to 1050m / g. The modified activated carbon provided by the invention has improved adsorption performance on xenon.

Description

Technical Field

[0001] This application relates to the field of radioactive waste treatment technology, and in particular to modified activated carbon for xenon adsorption and its preparation method. Background Technology

[0002] During the operation of nuclear facilities, the generation of radioactive xenon is an unavoidable byproduct of the nuclear fuel cycle. Currently, radioactive xenon handling technologies for nuclear facilities are mainly divided into two categories: pressurized storage decay technology and activated carbon retention technology. Activated carbon retention technology offers higher safety and economic efficiency, and can greatly improve the level of radioactive xenon handling technology in fast reactors.

[0003] Therefore, it is of great significance to develop an activated carbon material with improved xenon adsorption performance suitable for activated carbon retention technology. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a modified activated carbon for xenon adsorption and a method for preparing the same. Compared to unmodified initial activated carbon, the modified activated carbon significantly improves its xenon adsorption performance.

[0005] The first aspect of this application provides a modified activated carbon for xenon adsorption, wherein the modified activated carbon has a BET specific surface area of ​​1000 m² / g to 1050 m² / g.

[0006] In some embodiments, the total pore volume of the modified activated carbon is 0.5 cc / g to 0.6 cc / g.

[0007] In some embodiments, the micropore volume of the modified activated carbon is from 0.45 cc / g to 0.49 cc / g.

[0008] The second aspect of this application provides a method for preparing the above-mentioned modified activated carbon, comprising: step S1: preparing an aqueous solution of a modifier, wherein the modifier is selected from alkali metal hydroxides; step S2: impregnating initial activated carbon with the aqueous solution of the modifier prepared in step S1 to obtain initial activated carbon impregnated with the modifier; step S3: drying the initial activated carbon impregnated with the modifier obtained in step S2 to obtain dried initial activated carbon impregnated with the modifier; step S4: activating the dried initial activated carbon impregnated with the modifier obtained in step S3 at an activation temperature of 770°C to 970°C for 2.5 hours to 3.5 hours under an inert gas atmosphere to obtain modified activated carbon.

[0009] In some embodiments, during the impregnation process in step S2, the mass ratio of the modifier used to the initial activated carbon is 1 to 2.5.

[0010] In some embodiments, in step S2, the impregnation is carried out at room temperature.

[0011] In some embodiments, in step S2, the impregnation is carried out for 12 to 24 hours.

[0012] In some embodiments, in step S3, drying is carried out at a temperature of 90°C to 120°C.

[0013] In some implementations, in step S3, drying is carried out for 5.5 to 6.5 hours.

[0014] In some embodiments, the initial activated carbon is selected from one or more of coconut shell A activated carbon, coconut shell B activated carbon, coconut shell C activated carbon, apricot shell A activated carbon, apricot shell B activated carbon, and coal-based activated carbon.

[0015] In this application, the initial activated carbon was modified by using alkali metal hydroxides, which increased the BET specific surface area of ​​the activated carbon and the richness of the microporous structure, thereby improving the adsorption performance of xenon. Attached Figure Description

[0016] Figure 1 A flowchart illustrating the operation of a method for preparing modified activated carbon according to an embodiment of this application is shown.

[0017] Figure 2 A process flow diagram of the method for preparing modified activated carbon in Example 1 of this application is shown.

[0018] Figure 3 The micropore size distribution curves of the modified activated carbon prepared in Example 1 of this application and the coconut shell A activated carbon in Comparative Example 1 are shown.

[0019] Figure 4 The X-ray diffraction (XRD) images of the modified activated carbon prepared in Example 1 of this application and the coconut shell A activated carbon in Comparative Example 1 are shown.

[0020] Figure 5 The images show scanning electron microscope (SEM) images of the modified activated carbon prepared in Example 1 of this application and the coconut shell A activated carbon in Comparative Example 1.

[0021] Figure 6 Transmission electron microscope (TEM) images of the modified activated carbon prepared in Example 1 of this application and the coconut shell A activated carbon in Comparative Example 1 are shown. Detailed Implementation

[0022] The technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the implementation methods of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0023] Throughout this specification, unless otherwise specified, the terminology used herein should be understood as having the meaning commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In the event of any conflict, this specification shall prevail.

[0024] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or method that comprises a list of elements includes not only the elements expressly stated, but also other elements not expressly listed, or elements inherent to implementing the product, method, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other related elements in the product or method that includes that element.

[0025] In this application, "total pore volume" refers to the total volume of all pores in a unit mass of material, including micropores, mesopores, and macropores.

[0026] In this application, "micropore volume" refers to the volume of pores with a diameter of less than 2 nm, according to the IUPAC classification standard.

[0027] During the operation of nuclear facilities, the generation of radioactive xenon is an unavoidable byproduct of the nuclear fuel cycle. Currently, radioactive xenon handling technologies for nuclear facilities are mainly divided into two categories: pressurized storage decay technology and activated carbon retention technology. Activated carbon retention technology offers higher safety and economic efficiency, and can greatly improve the level of radioactive xenon handling technology in fast reactors.

[0028] Therefore, it is of great significance to develop an activated carbon material with improved xenon adsorption performance suitable for activated carbon retention technology.

[0029] In view of this, the first aspect of this application provides a modified activated carbon for xenon adsorption, wherein the modified activated carbon has a BET specific surface area of ​​1000 m² / g to 1050 m² / g.

[0030] The modified activated carbon in this application has an increased BET specific surface area compared to the unmodified initial activated carbon, which increases the number of contact sites for active sites. This increases the probability of xenon molecules coming into contact with the active sites, thereby improving the adsorption performance of xenon.

[0031] In this application, the BET specific surface area test and pore structure analysis of the modified activated carbon can be performed with reference to GB / T 7702.20-2008 "Test Methods for Coal-based Granular Activated Carbon: Determination of Pore Volume and Specific Surface Area".

[0032] In some embodiments, the total pore volume of the modified activated carbon is between 0.5 cc / g and 0.6 cc / g. A total pore volume within this range indicates that the modified activated carbon has a relatively large total pore volume. The increased total pore volume provides more space within the activated carbon to adsorb and accommodate xenon molecules, thereby further enhancing its xenon adsorption performance.

[0033] In some embodiments, the micropore volume of the modified activated carbon is between 0.45 cc / g and 0.49 cc / g. The adsorption performance of the modified activated carbon for xenon is mainly determined by the micropore portion. A micropore volume within the above range indicates a relatively large micropore volume of the modified activated carbon, meaning that the activated carbon contains more active sites with stronger adsorption capacity. These sites generate stronger molecular forces with xenon, thereby further enhancing the adsorption performance for xenon.

[0034] The second aspect of this application provides a method for preparing the modified activated carbon of the first aspect of this application. For example... Figure 1 As shown, the method includes: Step S1: preparing an aqueous solution of a modifier, wherein the modifier is selected from alkali metal hydroxides; Step S2: impregnating the initial activated carbon with the aqueous solution of the modifier prepared in Step S1 to obtain initial activated carbon impregnated with the modifier; Step S3: drying the initial activated carbon impregnated with the modifier obtained in Step S2 to obtain dried initial activated carbon impregnated with the modifier; Step S4: activating the dried initial activated carbon impregnated with the modifier obtained in Step S3 at an activation temperature of 770°C to 970°C for 2.5 hours to 3.5 hours under an inert gas atmosphere to obtain modified activated carbon.

[0035] In some embodiments, the alkali metal hydroxide is KOH.

[0036] To improve the xenon adsorption performance of activated carbon, this application modifies the activated carbon using a chemical activation method. The preparation method described in this application effectively increases the xenon adsorption performance of the modified activated carbon compared to the initial activated carbon. Furthermore, the chemical activation method in this application requires a shorter activation time, enabling the activation process of the activated carbon to be completed in a shorter period, thereby improving production efficiency and reducing production costs.

[0037] To avoid being bound by any theoretical constraints, the modifier in this application acts as a pore-forming agent. During the preparation of modified activated carbon, the modifier diffuses onto the surface of the initial activated carbon, further diffusing inwards through the pores on the outer surface. Then, the modifier reacts with the initial activated carbon, producing gas and alkali metal. Due to the collapse of the microstructure within the activated carbon, this means the alkali metal can be well embedded within it. Subsequently, at a high-temperature activation temperature, the metal vaporizes, and other gases continue to be generated, diffusing outwards through the pores. The gases produced by the reaction continuously flush the internal pores of the activated carbon, forming more microchannels, completing pore formation, and finally diffusing into the atmosphere. This method can gradually optimize the pore structure of activated carbon, ultimately increasing the specific surface area and the richness of the microporous structure, resulting in modified activated carbon with improved xenon adsorption performance.

[0038] In this application, the activation temperature is between 770°C and 970°C. Studies have found that when the activation temperature is below 770°C, the modifier's performance is not fully realized, and the changes in the internal pores of the activated carbon still tend towards macropores. Furthermore, unreacted modifier penetrates deep into the internal pores of the activated carbon, blocking the pore structure and thus weakening the xenon adsorption performance of the activated carbon. Simultaneously, some of the alkali metals generated from the reaction of the modifier become embedded in the pores, causing pore blockage and the disappearance of many microporous structures beneficial for adsorption. When the activation temperature is above 970°C, the activity of alkali metal vapors becomes too vigorous. Excessively high activation temperatures cause severe collapse of the activated carbon's framework structure, making it difficult to achieve a good pore-expanding effect, thus weakening the adsorption performance of the activated carbon. Exemplarily, the activation temperature can be a value between 770°C, 790°C, 820°C, 850°C, 870°C, 880°C, 910°C, 940°C, 970°C, or any combination thereof.

[0039] In this application, the activation time is 2.5 to 3.5 hours. Studies have found that when the activation time is less than 2.5 hours, the energy provided by the activation time for the activation process is relatively low, and some modifiers do not fully participate in the reaction with the initial activated carbon structure, resulting in fewer channels being formed. At this time, the pore expansion mainly involves transforming micropores into macropores and mesopores, leading to a decrease in the number of micropores, and consequently, a decrease in the adsorption performance of the initial activated carbon. When the activation time is greater than 3.5 hours, lateral pore expansion occurs, the activated carbon skeleton is severely eroded, and the internal spatial structure is destroyed, resulting in a decrease in the number of pores with optimal pore size for xenon adsorption, thus weakening the adsorption performance of the activated carbon. Exemplarily, activation can be performed for values ​​between 2.5 hours, 2.7 hours, 3 hours, 3.2 hours, 3.5 hours, or any combination thereof.

[0040] In some embodiments, during the impregnation process in step S2, the mass ratio of the modifier to the initial activated carbon is between 1 and 2.5. Studies have found that during the impregnation process in step S2, when the mass ratio of the modifier to the initial activated carbon is 1, the amount of modifier used is insufficient, and some activated carbon cannot be activated, so the adsorption performance is not significantly improved. As the ratio increases to 1.5 and 2, sufficient modifier further enriches the pore structure, making the reaction more thorough, further removing internal impurities and forming new channels. Further increasing the amount of modifier, however, causes the modifier to severely erode the carbon skeleton, leading to excessive combustion of the carbon, widening of pores, and disappearance of pore walls, ultimately reducing the original micropores and causing a decrease in adsorption performance. For example, during the impregnation process in step S2, the mass ratio of the modifier to the initial activated carbon is a value within the range of 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.5, or any two of these values.

[0041] In some embodiments, in step S2, the impregnation lasts for 12 to 24 hours. This allows the modifier to be fully impregnated within the initial activated carbon, facilitating subsequent activation reactions. Exemplarily, the impregnation can be performed for 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, or a range thereof.

[0042] In some embodiments, the impregnation in step S2 can be carried out at room temperature.

[0043] In some embodiments, in step S3, drying can be carried out at a temperature of 90°C to 120°C. This facilitates sufficient evaporation of the solvent, allowing the modifier to adhere to the initial activated carbon. Exemplarily, the drying temperature can be a value between 90°C, 100°C, 105°C, 110°C, 120°C, or any combination thereof.

[0044] In some embodiments, drying in step S3 can be performed for 5.5 to 6.5 hours. This facilitates sufficient evaporation of the solvent. Exemplarily, drying can be performed for a range of 5.5 hours, 6 hours, 6.5 hours, or any combination thereof.

[0045] In some embodiments, the initial activated carbon is selected from one or more of coconut shell A activated carbon, coconut shell B activated carbon, coconut shell C activated carbon, apricot shell A activated carbon, apricot shell B activated carbon, and coal-based activated carbon. Optionally, the initial activated carbon is selected from coconut shell A activated carbon. For example, coconut shell A activated carbon and coconut shell B activated carbon can be purchased from Zhengzhou Zhongliao Environmental Protection Technology Co., Ltd. For example, coconut shell C activated carbon can be purchased from Zhejiang Jingshui Environmental Protection Co., Ltd. For example, apricot shell A activated carbon and apricot shell B activated carbon can be purchased from Henan Dongcui Carbon Material Technology Co., Ltd. For example, coal-based activated carbon can be purchased from Tianbang Environmental Protection Technology Co., Ltd.

[0046] In some embodiments, the method of this application may further include a step of cleaning the initial activated carbon. To remove impurities from the initial activated carbon, it may be cleaned with deionized water before impregnation. Cleaning may be performed multiple times until the deionized water remains clear.

[0047] In some embodiments, the method of this application may further include a step of drying the cleaned initial activated carbon. Drying the cleaned initial activated carbon may be carried out, for example, at a temperature of 90°C to 120°C, and optionally, at 105°C. The drying of the cleaned initial activated carbon may be carried out, for example, for 5.5 hours to 6.5 hours, and optionally, for 6 hours. This facilitates the subsequent impregnation step.

[0048] A third aspect of this application also provides the use of the modified activated carbon described in the first aspect of this application for the adsorption of xenon gas. In this use, the modified activated carbon is packed in a radioactive xenon gas retention bed.

[0049] The present application is described in more detail below through embodiments. It should be understood that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product instructions. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be obtained commercially.

[0050] Example 1 The modified activated carbon for xenon adsorption in Example 1 was prepared by the following operation.

[0051] (1) Weigh 220g of coconut shell A activated carbon (purchased from Zhengzhou Zhongliao Environmental Protection Technology Co., Ltd.) using an electronic balance, place it in a beaker, and add 1000mL of distilled water to obtain a mixture. Stir the mixture using a magnetic stirrer, adjusting the rotor until a vortex appears, so that the activated carbon at the bottom edge of the beaker rotates fully. Stir for 10 minutes at room temperature, and then filter. Repeat the washing of coconut shell A activated carbon 7 times until the supernatant is clear, to obtain the washed coconut shell A activated carbon.

[0052] (2) After the above-mentioned cleaned coconut shell A activated carbon is filtered through a sieve, it is placed on a metal tray, spread out, and then placed in an oven to dry at 105℃ for 6 hours. After cooling, it is taken out and stored in a sealed bag for later use.

[0053] (3) Weigh 1000mL of distilled water using a graduated cylinder and pour it into a beaker. Then weigh 200g of KOH solid. While stirring, slowly pour the weighed KOH solid into the beaker containing 1000mL of distilled water and continue stirring for 5min.

[0054] (4) Weigh 100g of the activated carbon obtained in operation (2) after cleaning, drying and cooling, so that the mass ratio of the modifier KOH to the activated carbon is 2. Add the activated carbon to the KOH aqueous solution prepared in operation (3), stir for 5min until it is evenly mixed, seal it with a sealing film, write a label, and soak it at room temperature for 24h.

[0055] (5) Filter the impregnated activated carbon through a sieve to separate the solid and liquid phases, and obtain activated carbon impregnated with KOH. Spread the KOH-impregnated activated carbon evenly in two metal trays, and then place the metal trays containing the activated carbon into two high-temperature ovens and dry them at 105°C for 6 hours.

[0056] (6) Take the dried activated carbon from operation (5), place it evenly on the quartz boat, place the quartz boat stably in the tube furnace, and seal it well.

[0057] (7) Ensure the pressure reducing valve is closed. First, turn on the power to the mass flow meter. Set the setpt value in the upper right corner of the mass flow meter to 0.3. Connect the mass flow meter and determine the gas inlet and outlet directions. Adjust the pressure reducing valve of the tubular furnace to allow nitrogen to flow in at a rate of 300 mL / min for 45 minutes, and then discharge other gases.

[0058] (8) Adjust the heating program to raise the temperature to the set activation temperature of 870°C at a heating rate of 5°C / min, and maintain this temperature for 3 hours, i.e., activate the KOH-impregnated activated carbon for 3 hours. After the temperature inside the tubular furnace cools down to below 100°C, remove the activated carbon and then close the nitrogen valve. Close the main valve of the gas cylinder, wait for the pressure gauge to drop to 0, disconnect the inlet section of the mass flow meter, and unplug the power supply. The modified activated carbon of Example 1 is thus obtained.

[0059] The process flow diagram of the method for preparing modified activated carbon in Example 1 is shown in... Figure 2 middle.

[0060] Comparative Example 1 The activated carbon in Comparative Example 1 was unmodified and was the initial activated carbon, coconut shell A activated carbon, used in Example 1.

[0061] Tests for activated carbon BET specific surface area testing and pore structure analysis The activated carbon was tested according to GB / T 7702.20-2008 "Test Methods for Coal-based Granular Activated Carbon: Determination of Pore Volume and Specific Surface Area" to obtain the specific surface area and corresponding pore structure parameters. A pore size distribution curve for the micropore portion was also plotted. The specific surface area and pore structure parameters are shown in Table 1 below, and the pore size distribution curve for the micropore portion is shown in... Figure 3 As shown in the image.

[0062] XRD test X-ray diffraction analysis was performed on activated carbon using an X-ray diffractometer.

[0063] SEM test Activated carbon was tested using a scanning electron microscope, and SEM images were obtained at magnifications of 60k, 30k, and 10k.

[0064] TEM test Activated carbon was tested using a transmission electron microscope, and TEM images were obtained at 50 nm and 5 nm scales, respectively.

[0065] Xenon adsorption test method The xenon adsorption coefficient of activated carbon was tested according to the test method in "NB / T 20143.3-2017, Nuclear Air and Gas Treatment Specification Process Gas Treatment Part 3: Radioactive Waste Gas Retention Equipment [S], National Energy Administration, 2017.04.01". The test conditions were: room temperature 25℃, pressure 0.002 MPa, carrier gas type argon, carrier gas flow rate 0.63 cm / s, and carbon bed length-to-diameter ratio 6:1.

[0066] The dynamic adsorption coefficient is calculated using the following formula:

[0067] In the formula, K dis the dynamic adsorption coefficient, in mL / g, characterizing the ability of activated carbon to adsorb and retain inert gases; F is the gas flow rate, in mL / min; M is the mass of activated carbon, in g; t is the residence time, in min, which is the time corresponding to the peak value of the effluent for pulsed tests, and the time corresponding to 50% breakthrough for continuous tests.

[0068] Results Analysis BET specific surface area test and pore structure parameters The activated carbon in Example 1 and Comparative Example 1 were tested according to the above test methods, and the corresponding test parameters are shown in Table 1 below.

[0069] Xenon adsorption performance The activated carbon in Example 1 and Comparative Example 1 were tested according to the above test methods, and the corresponding test parameters are shown in Table 1 below.

[0070] Table 1: Performance parameters of activated carbon from Example 1 and Comparative Example 1

[0071] As shown in Table 1, the adsorption coefficient of the modified activated carbon for xenon significantly increased from 620.33 ml / g to 732.45 ml / g. This improvement in adsorption performance is due to the combined effect of specific surface area and micropores. The increased specific surface area after modification increases the number of adsorption sites for active sites, thus increasing the probability of xenon molecules contacting these sites. The increased total pore volume provides more space within the activated carbon to adsorb and accommodate gas molecules. Simultaneously, the increased micropore volume indicates the presence of more active sites with stronger adsorption capabilities within the activated carbon. These sites generate stronger molecular forces with xenon, thereby improving the performance of the activated carbon.

[0072] Micropore size distribution curve The pore size distribution curve of the micropores is in Figure 3 As shown in the image. From Figure 3As can be seen, the pore diameter distribution of activated carbon micropores exhibits a typical single-peak distribution between 0.2 nm and 2 nm. The peak value of coconut shell activated carbon A appears between 0.5 nm and 0.8 nm. The peak value of modified activated carbon shifts towards 0.8 nm. While the pore size below 0.5 nm does not change significantly, the increase in pore size between 0.6 nm and 1 nm is more pronounced, with a stronger peak. This indicates that potassium hydroxide modification further develops the micropores of activated carbon, and the pore-forming effect of the activation products contributes more significantly to the micropores in the 0.6 nm to 1 nm size range. In the 0.6 nm to 1 nm size range, activated carbon contains more active sites with stronger adsorption capacity. These sites generate stronger molecular forces with xenon, thus further enhancing the adsorption performance of xenon. In the 0.6 nm to 1 nm size range, the pore segment distribution advantage is more obvious, and the number of micropores is significantly increased, which is more favorable for xenon adsorption.

[0073] XRD test XRD tests were performed on the activated carbon of Example 1 and Comparative Example 1 according to the above test methods. The obtained XRD patterns are shown in the figure. Figure 4 As shown in the image.

[0074] from Figure 4 As can be seen, both materials exhibit two distinct diffraction peaks in the 20° to 60° range. The peak appearing around 24° is the 002 lattice plane diffraction peak of activated carbon, which corresponds well to standard graphite. This is due to the continuous parallel graphite layers. The presence of the 002 lattice diffraction peak before and after modification indicates that both materials contain disordered graphite layers. The diffuse diffraction peaks suggest a large amount of amorphous carbon within the materials. The modified activated carbon's 002 diffraction peak is weaker and has a wider peak width distribution, indicating that the products of KOH activation cause the carbon layers to twist and crack, significantly reducing the degree of graphitization and crystallinity. This suggests that the internal pores of the modified activated carbon are more fully developed. The diffraction peak appearing near 43° is the 101 graphite crystal plane peak, and its formation may be related to the R-axis of the graphite structure. Figure 4 The diffraction peak intensity and peak width of the C100 crystal plane of the activated carbon before and after modification did not change significantly. The peak shape remained dome-shaped, indicating that the degree of lattice distortion and shrinkage was high before and after modification. The increased disorder and lattice distortion and shrinkage resulted in a more compact and richer pore structure in the activated carbon.

[0075] SEM test The activated carbons of Example 1 and Comparative Example 1 were tested according to the above testing methods, and SEM images were obtained at magnifications of 60K, 30K, and 10K, respectively. The modified activated carbon of Example 1 corresponds to... Figure 5 In (a) to (c), the activated carbon of Comparative Example 1 corresponds to Figure 5 (d) to (f) in the middle.

[0076] At 10k magnification (c) and (f) , the modified activated carbon exhibits more surface collapse, higher pore fragmentation, more scattered distribution, and a significantly increased number of pores compared to coconut shell A activated carbon. At 30k magnification (b) and (e) , a certain number of smooth planes can be observed in coconut shell A activated carbon. The modified activated carbon, after KOH activation, effectively corrodes the surface of the coconut shell carbon. The smooth surfaces extend and collapse into the carbon body, etching the carbon skeleton and developing a honeycomb structure, further increasing existing pores and providing contact points for micropore formation. At 60k magnification (a) and (d) , the modified activated carbon is found to have a denser micropore structure than coconut shell A activated carbon, indicating a deterioration of the carbon skeleton. The irregular morphology and the presence of the microporous structure make the material highly suitable for adsorbing xenon molecules.

[0077] TEM test The activated carbon of Example 1 and Comparative Example 1 were subjected to TEM testing according to the above test method, and TEM images were obtained at 50 nm and 5 nm scales, respectively. The modified activated carbon of Example 1 corresponds to Figure 6 (c) to (d) in the examples correspond to the activated carbon of Comparative Example 1. Figure 6 (a) and (b) in the example.

[0078] from Figure 6 As can be seen, at the 5nm scale, white bright spots are widely distributed and abundant. Compared to the scale, their size is mostly below 1nm, indicating a microporous structure. These microporous spots constitute a significant portion of the pore distribution, suggesting that micropores contribute more to the development of the pore structure. At the 50nm scale, both exhibit stacked lamellar structures with a clear amorphous structure. Although neither showed ordered carbon layers or other graphitized structures, the modified carbon after potassium hydroxide activation exhibited a more complex lamellar structure. Figure 6 The layering is more pronounced in (c) of the image. A comparison of coconut shell activated carbon (A type) and modified activated carbon on a 5nm scale shows... Figure 6 In (b), it can be seen that the white bands of the original activated carbon appear linearly (marked in red). The white bands represent the distribution of the pore structure of the activated carbon, indicating that the micropores of the unmodified activated carbon are more ordered. From... Figure 6 In (d), the white bands were observed to be more disordered, which means that the degree of order of the pores in the modified activated carbon decreased and the pore structure was more complete.

[0079] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A modified activated carbon for xenon adsorption, characterized in that, The modified activated carbon has a BET specific surface area of ​​1000 m² / g to 1050 m² / g.

2. The modified activated carbon according to claim 1, wherein, The total pore volume of the modified activated carbon is 0.5 cc / g to 0.6 cc / g.

3. The modified activated carbon according to claim 1 or 2, wherein, The modified activated carbon has a micropore volume of 0.45 cc / g to 0.49 cc / g.

4. A method for preparing modified activated carbon according to any one of claims 1 to 3, characterized in that, The method includes: Step S1: Prepare an aqueous solution of the modifier, wherein the modifier is selected from alkali metal hydroxides; Step S2: Impregnate the initial activated carbon with the aqueous solution of the modifier prepared in step S1 to obtain initial activated carbon impregnated with the modifier. Step S3: Dry the initial activated carbon impregnated with the modifier obtained in step S2 to obtain dried initial activated carbon impregnated with the modifier. Step S4: Under an inert gas atmosphere and at an activation temperature of 770°C to 970°C, the dried initial activated carbon impregnated with the modifier obtained in step S3 is activated for 2.5 hours to 3.5 hours to obtain the modified activated carbon.

5. The method according to claim 4, wherein, During the impregnation process in step S2, the mass ratio of the modifier to the initial activated carbon is 1 to 2.

5.

6. The method according to claim 4 or 5, wherein, In step S2, the impregnation is carried out at room temperature.

7. The method according to any one of claims 4 to 6, wherein, In step S2, the impregnation process lasts for 12 to 24 hours.

8. The method according to any one of claims 4 to 7, wherein, In step S3, the drying is carried out at a temperature of 90°C to 120°C.

9. The method according to any one of claims 4 to 8, wherein, In step S3, the drying process takes 5.5 to 6.5 hours.

10. The method according to any one of claims 4 to 9, wherein, The initial activated carbon is selected from one or more of coconut shell A activated carbon, coconut shell B activated carbon, coconut shell C activated carbon, apricot shell A activated carbon, apricot shell B activated carbon, and coal-based activated carbon.

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