A nickel-metal embedded porous carbon adsorbent, its preparation method and application

Abstract

This invention relates to a nickel metal embedded porous carbon adsorbent, its preparation method, and its application, comprising the following steps: S1, adding a nickel salt solution dropwise to nano-silica, drying it, and then adding biomass for grinding; S2, pre-carbonizing the product after grinding in step S1 at a low temperature; S3, carbonizing the product after pre-carbonization in step S2 at a high temperature under inert gas protection; S4, adding an alkaline solution to the product after high-temperature carbonization in step S3 to remove the nano-silica, thereby obtaining the nickel metal embedded porous carbon adsorbent. Compared with the prior art, this invention has a unique embedded structure, which improves the stability of the metal sites, and has a large specific surface area and pore volume, thereby improving the selective adsorption capacity for Xe and effectively separating Kr and Xe.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials technology, and in particular to a nickel metal embedded porous carbon adsorbent, its preparation method, and its application. Background Technology

[0002] Among numerous alternative clean energy sources, nuclear energy plays a dominant role. In 2020, there were 448 nuclear power units worldwide, generating approximately 16% of the total electricity. However, the disposal of spent fuel generated after nuclear energy utilization is a thorny issue. This is because nuclear fission produces various nuclides, many of which are unstable radioactive nuclides, including isotopes of the inert gases krypton (Kr) and xenon (Xe). Direct release into the atmosphere would pose radiation hazards to the environment and living organisms. Furthermore, Kr-85 has very broad application prospects in areas such as thickness measurement, nuclear lamps, and flaw detection. Therefore, the effective recovery of radioactive gases and the technology for tail gas recovery present even greater challenges.

[0003] Currently, methods such as low-temperature activated carbon adsorption, low-temperature distillation, and low-temperature solvent absorption are commonly used to recover Kr-85 from exhaust gases during spent fuel reprocessing. However, the chemical purity of Kr-85 gas prepared by these methods is relatively low, with Xe being the main impurity. This fails to meet the purity requirements for industrial radioactive source and isotope separation, necessitating further separation and purification. Low-temperature chromatography is commonly used for separation and purification, with zeolite, molecular sieves, or activated carbon typically used as packing materials. While these materials exhibit high adsorption capacities for Kr and Xe, they show low selectivity. Therefore, developing novel adsorbent materials with high selectivity and large adsorption capacity is crucial. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art, such as low separation and purification efficiency and low selectivity, and to provide a nickel metal embedded porous carbon adsorbent, its preparation method and application.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a method for preparing a nickel metal embedded porous carbon adsorbent, comprising the following steps:

[0007] S1. Add nickel salt solution dropwise to nano-silica, dry it, and then add biomass for grinding;

[0008] S2. The product ground in step S1 is pre-carbonized at low temperature.

[0009] S3. The product pre-carbonized in step S2 is subjected to high-temperature carbonization under inert gas protection.

[0010] S4. Add alkaline solution to the product after high-temperature carbonization in step S3 to remove nano-silica and obtain nickel metal embedded porous carbon adsorbent.

[0011] In some specific embodiments, in step S1, the nickel salt solution is selected from any one or more of nickel chloride solution, nickel nitrate solution, or nickel sulfate solution.

[0012] In some specific embodiments, in step S1, the particle size of the nano-silica is selected from any one of 5nm, 10nm, 25nm or 50nm.

[0013] In some specific embodiments, in step S1, the biomass is selected from any one of cellulose, lignin, cyclodextrin, glucose, or sucrose.

[0014] In some specific embodiments, in step S1, the nickel salt solution contains 0.01 mmol of nickel salt by mass, and the ratio of the 0.01 mmol nickel salt solution, nano-silica, and biomass is 2 mL: 1 g: 2 g.

[0015] The grinding time is 1-8 hours.

[0016] In some specific embodiments, in step S2, the pre-carbonization temperature is 120-300°C and the pre-carbonization time is 8-24 hours.

[0017] In some specific embodiments, in step S3, the high-temperature carbonization temperature is 500-1300℃, and the high-temperature carbonization time is 1-12h; the inert gas is nitrogen.

[0018] In some specific embodiments, in step S4, the alkaline solution is selected from any one of potassium hydroxide, sodium hydroxide, or calcium hydroxide.

[0019] The second technical solution of the present invention is to provide a nickel metal embedded porous carbon adsorbent, which is prepared based on the preparation method described in one of the above technical solutions.

[0020] The third technical solution of the present invention is to provide an application of the nickel metal embedded porous carbon adsorbent as described in the second technical solution above, wherein the nickel metal embedded porous carbon adsorbent is used for the separation of krypton and xenon.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) This invention is based on the fact that Kr and Xe have a certain difference in polarizability, with Kr having a polarizability of 24.844 × 10⁻⁶. -25 cm 3 The polarizability of Xe is 40.44 × 10⁻⁶. -25 cm 3By modifying porous carbon to introduce open metal sites and adjusting the polarization environment of the material, its selective adsorption capacity for Xe is improved, thereby achieving efficient separation of Kr and Xe.

[0023] (2) The nickel metal embedded porous carbon adsorbent prepared by the present invention has a unique embedded structure, which improves the stability of the metal sites and has a large specific surface area and pore volume, which improves the selective adsorption capacity for Xe and can effectively separate Kr and Xe. Attached Figure Description

[0024] Figure 1 Nickel metal embedded porous carbon (Ni@MC) prepared from different nickel sources in Examples 1-3 -N Nickel nitrate source; Ni@MC -S Nickel sulfate source; Ni@MC -Cl (Ni chloride source). Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0026] Unless otherwise specified, the raw materials or processing techniques used in the following embodiments and comparative examples are all conventional commercially available raw materials or conventional processing techniques in the art.

[0027] Example 1:

[0028] 20 mL of 0.01 mmol nickel nitrate aqueous solution was added dropwise to 10 g of silica powder with a particle size of 10 nm while stirring continuously. The resulting slurry was dried at 120 °C for 24 h, cooled to room temperature, and then 20 g of cellulose was added to the solid followed by ball milling for 8 h. The resulting powder was pre-carbonized at 180 °C for 18 h, and then carbonized at 1100 °C for 6 h under nitrogen protection. The resulting black powder was added to 50 mL of 2 mol / L sodium hydroxide solution and stirred for 8 h. The mixture was filtered and thoroughly washed with deionized water until neutral, then dried to obtain a nickel metal-embedded porous carbon adsorbent.

[0029] Example 2:

[0030] The process is largely the same as in Example 1, except that the "nickel nitrate aqueous solution" is replaced with the "nickel chloride aqueous solution". The specific preparation process is as follows:

[0031] 20 mL of 0.01 mmol nickel chloride aqueous solution was added dropwise to 10 g of silica powder with a particle size of 10 nm while stirring continuously. The resulting slurry was dried at 120 °C for 24 h, cooled to room temperature, and then 20 g of cellulose was added to the solid followed by ball milling for 8 h. The resulting powder was pre-carbonized at 180 °C for 18 h, and then carbonized at 1100 °C for 6 h under nitrogen protection. The resulting black powder was added to 50 mL of 2 mol / L sodium hydroxide solution and stirred for 8 h. The mixture was filtered and thoroughly washed with deionized water until neutral, then dried to obtain a nickel metal-embedded porous carbon adsorbent.

[0032] Example 3:

[0033] The process is largely the same as in Example 1, except that the "nickel nitrate aqueous solution" is replaced with the "nickel sulfate aqueous solution". The specific preparation process is as follows:

[0034] 20 mL of 0.01 mmol nickel sulfate aqueous solution was added dropwise to 10 g of silica powder with a particle size of 10 nm while stirring continuously. The resulting slurry was dried at 120 °C for 24 h, cooled to room temperature, and then 20 g of cellulose was added to the solid followed by ball milling for 8 h. The resulting powder was pre-carbonized at 180 °C for 18 h, and then carbonized at 1100 °C for 6 h under nitrogen protection. The resulting black powder was added to 50 mL of 2 mol / L sodium hydroxide solution and stirred for 8 h. The mixture was filtered and thoroughly washed with deionized water until neutral, then dried to obtain a nickel metal-embedded porous carbon adsorbent.

[0035] The products obtained in Examples 1-3 were characterized by XRD, such as... Figure 1 As shown. The samples of Examples 1-3 all showed obvious Ni diffraction peaks (JCPDS 04-0850), which correspond to the (111), (200) and (220) crystal planes of Ni, respectively. Among them, the (111) crystal plane of Ni has the highest diffraction intensity, which indicates that Ni@MC is mainly dominated by this crystal plane.

[0036] Comparative Example 1:

[0037] The process is largely the same as in Example 1, except that the nickel source is omitted. The specific preparation process is as follows:

[0038] 10g of silica powder with a particle size of 10nm was mixed with 20g of cellulose and ball-milled for 8h. The resulting powder was pre-carbonized at 180℃ for 18h, and then carbonized at 1100℃ for 6h under nitrogen protection. The resulting black powder was added to 50mL of 2mol / L sodium hydroxide solution and stirred for 8h. The mixture was filtered and thoroughly washed with deionized water until neutral, and then dried.

[0039] The adsorption performance of the adsorbents prepared in Examples 1-3 and Comparative Example 1 for Xe was studied by static adsorption experiments. As shown in Table 1, the nickel-metal-embedded porous carbon material prepared with nickel nitrate as the nickel source had the largest adsorption capacity for Xe. Compared with the porous carbon without added nickel, the adsorption capacity for Xe was significantly improved, indicating that the introduction of nickel metal sites improved the adsorption capacity of the porous material for Xe.

[0040] Table 1. Adsorption capacity of Xe by nickel metal embedded porous carbon materials prepared with different nickel sources

[0041] Nickel source Adsorption capacity / mmol / g Example 1 Nickel nitrate 0.83 Example 2 Nickel chloride 0.61 Example 3 Nickel sulfate 0.71 Comparative Example 1 - 0.55

[0042] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. Use of a nickel damascene porous carbon adsorbent, characterized in that, The nickel-metal embedded porous carbon adsorbent is used for the separation of krypton and xenon, improving the selective adsorption capacity for Xe. The preparation method of the nickel metal embedded porous carbon adsorbent includes the following steps: S1. Add nickel salt solution dropwise to nano-silica, dry it, and then add biomass for grinding; S2. The product ground in step S1 is pre-carbonized at low temperature. S3. The product pre-carbonized in step S2 is subjected to high-temperature carbonization under inert gas protection. S4. Add alkaline solution to the product after high-temperature carbonization in step S3 to remove nano-silica and obtain nickel metal embedded porous carbon adsorbent. In step S1, the biomass is selected from any one of cellulose, lignin, and cyclodextrin; the particle size of the nano-silica is selected from any one of 5 nm, 10 nm, 25 nm, or 50 nm. In step S2, the pre-carbonization temperature is 120-300℃ and the pre-carbonization time is 8-24 h; In step S3, the high-temperature carbonization temperature is 500-1300℃, and the high-temperature carbonization time is 1-12 h; the inert gas is nitrogen.

2. The use of a nickel damascene porous carbon adsorbent according to claim 1, characterized by, In step S1, the nickel salt solution is selected from any one or more of nickel chloride solution, nickel nitrate solution, or nickel sulfate solution.

3. The application of the nickel metal embedded porous carbon adsorbent according to claim 1, characterized in that, In step S1, the ratio of nickel salt solution, nano-silica, and biomass is 2 mL: 1 g: 2 g. The grinding time is 1-8 hours.

4. The application of the nickel metal embedded porous carbon adsorbent according to claim 1, characterized in that, In step S4, the alkaline solution is selected from any one of potassium hydroxide, sodium hydroxide, or calcium hydroxide.

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