Application of efficiently trapping trace krypton by using pure silicon molecular sieve under humid condition
By using the pure silicon molecular sieve ZSM-11 in the MEL configuration, the problem of insufficient selectivity for krypton gas adsorption in humid environments is solved, and efficient capture and enrichment of trace krypton gas is achieved, which is suitable for nuclear facilities exhaust gas treatment and radiogas monitoring.
Patent Information
- Application Number
- CN202510593684.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-08
- Publication Date
- 2025-08-12
AI Technical Summary
The adsorption selectivity of existing molecular sieves to krypton gas in humid environments is not high, which affects the capture effect of trace amounts of krypton gas. Moreover, the performance of traditional molecular sieves decreases under high humidity, making it difficult to achieve efficient separation and enrichment.
The pure silicon molecular sieve ZSM-11 with MEL configuration is used as an adsorbent to capture krypton gas under wet conditions. The topological structure and hydrophobicity of the molecular sieve are controlled by synthesis method, and the selective adsorption performance of krypton gas and nitrogen is improved, and a good dynamic penetration effect is maintained under high humidity.
Under the conditions of relative humidity as high as 72.6%, pure silicon molecular sieve ZSM-11 achieves efficient capture of trace krypton gas, with Kr/N2 selectivity greater than 4, enriched krypton gas purity greater than 85%, and maintains stable performance in multiple cycles. It is suitable for nuclear facility exhaust gas treatment and radiogas monitoring.
Smart Images
Figure HDA0005393878560000011 
Figure HDA0005393878560000021 
Figure HDA0005393878560000031
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of separation and capture of radioactive inert gases, and in particular to an application of a pure silicon molecular sieve for efficiently capturing trace krypton gas under humid conditions. Background Art
[0002] With the continuous growth of global energy demand and the increasingly serious problem of greenhouse gas emissions, nuclear energy is gradually becoming an important option for the transformation of energy structure due to its advantages of high energy density, low carbon emissions and stable energy supply. However, the widespread use of nuclear energy is accompanied by a series of safety and environmental management issues, especially the fission gases released during the nuclear fuel cycle, such as radioactive nuclides krypton and xenon. 85 Kr has attracted much attention due to its long half-life of 10.8 years. If it is directly released into the atmosphere, it may have long-term impacts on the environment. 85 The emission concentration of Kr can be used to monitor the operating status of nuclear facilities, assess the integrity of nuclear fuel, and provide environmental monitoring and emergency response data in the event of a radioactive leakage accident. 85 The separation and enrichment of Kr can be used to detect fission products released from underground nuclear tests. 85 The efficient capture of Kr is very important for protecting the environment.
[0003] At present, adsorption separation is the capture 85 Kr is a research hotspot. Existing research indicates that a variety of porous materials can be used for the adsorption and separation of radioactive noble gases, including activated carbon, metal-organic frameworks (MOFs), and molecular sieves. Molecular sieves offer excellent chemical and thermal stability, are non-flammable, and are considered safer and more reliable in practical applications. Therefore, they are considered a promising material for krypton capture.
[0004] In the prior art, CN115779854A discloses an adsorption separation application of a calcium-containing molecular sieve Ca-CHA, which can efficiently separate krypton-xenon mixtures and nitrogen-oxygen mixtures. The calcium-containing chabazite molecular sieve adsorbent Ca-CHA is synthesized using commercial Na-Y molecular sieve as raw material through ion exchange, crystallization and other steps. The prepared Ca-CHA molecular sieve has a strong local electric field and has a strong adsorption effect on xenon and nitrogen. Ca-CHA can selectively adsorb xenon from a krypton-xenon mixture to achieve krypton-xenon separation; and it can selectively adsorb nitrogen from a nitrogen-oxygen mixture and be used as a nitrogen selective adsorbent in the adsorption oxygen production process. However, the adsorption selectivity is not high, and a humid environment will reduce the adsorption effect, which is not conducive to krypton gas enrichment. Similarly, CN112551545B discloses a method for krypton-xenon separation using a high silicon-aluminum ratio molecular sieve membrane. It discloses that SSZ-13 and DD3R molecular sieve membranes for Kr / Xe separation are prepared on a porous ceramic carrier. The mass transfer channels of the two molecular sieve membranes are elliptical octagonal ring channels, which show higher diffusion selectivity. At the same time, thanks to the hydrophobic properties of the high silicon-aluminum ratio molecular sieve membrane, the separation performance and membrane stability of the molecular sieve membrane are basically unaffected by water vapor. Although the membrane materials involved in the invention are all aluminosilicate materials, they still maintain stable structure and performance in a nuclear radiation environment. High-silicon molecular sieve membranes can be used for krypton-xenon separation. Membrane separation has a good separation effect in a high-humidity environment, but it depends on the performance of the adsorption components of the synthetic membrane. The adsorption capacity of the molecular sieve SSZ-13 is still insufficient, and the adsorption of krypton gas by the molecular sieve before film formation is still insufficient, especially its adsorption selectivity still needs to be improved.
[0005] In view of the above problems, the present invention provides a method for efficiently capturing trace amounts of krypton gas using pure silicon molecular sieves under humid conditions. Summary of the Invention
[0006] The present invention provides an application of using pure silicon molecular sieve to efficiently capture trace krypton gas under humid conditions.
[0007] The pure silicon molecular sieve is a pure silicon molecular sieve ZSM-11 of MEL configuration; the relative humidity range of the humid environment is 0-75%; the pure silicon molecular sieve can achieve adsorption separation of krypton gas and air mixture;
[0008] Furthermore, compared with a dry environment, a humid environment does not substantially increase the krypton gas separation time;
[0009] Furthermore, the pure silicon molecular sieve can be enriched to obtain krypton gas with a purity greater than 85%;
[0010] Furthermore, at 298 K and 1 bar, the Kr adsorption capacity is greater than 12 cm 3 / g, Kr / N2 selectivity is greater than 4;
[0011] Furthermore, pure silicon molecular sieve still has good dynamic penetration effect under conditions of relative humidity as high as 72.6%. The dynamic penetration operating conditions are: adsorption column size Φ4.6×150mm, mixed gas flow rate of 3.5mL / min, and regeneration purge time less than 30min.
[0012] Furthermore, the pure silicon molecular sieve can be used to monitor trace amounts of radioactive noble gas Kr.
[0013] Furthermore, the synthesis method of pure silicon molecular sieve ZSM-11 is: tetrabutylammonium hydroxide, tetrabutylammonium silicate and distilled water are mixed in a reactor, stirred to fully dissolve, sealed and reacted at 155-175°C, and after the reaction is completed, the reaction product is washed, dried and calcined to obtain pure silicon molecular sieve ZSM-11.
[0014] Furthermore, the mass ratio of tetrabutylammonium hydroxide to tetrabutylammonium silicate is 1-1.2:1; the amount of distilled water added is 15-25% of the total mass of tetrabutylammonium hydroxide and tetrabutylammonium silicate; and the calcination conditions are a heating rate of 2°C / min, heating to 500-550°C, and a calcination time of 6-12 hours.
[0015] Technical Effects
[0016] The present invention overcomes the low selectivity of traditional molecular sieves for Kr by combining the topological structural characteristics of the molecular sieve with its hydrophobicity. It also solves the problem of the competitive adsorption of moisture in a humid environment affecting the capture performance of trace Kr, and achieves efficient capture of trace Kr gas in a high humidity environment. The pure silicon molecular sieve material in the present invention has higher Kr selective adsorption performance, with a Kr / N2 selectivity greater than 4, which is greater than the adsorption selectivity of SSZ-13 and other traditional molecular sieves, and a Kr concentration greater than 85% can be obtained in the desorption stage, which facilitates the subsequent monitoring of trace radioactive noble gases. At the same time, it still has a good dynamic penetration effect under conditions of relative humidity as high as 72.6%, good cyclic stability, and the performance remains stable in 5 penetration cycles. In addition, this method is simple to operate, has low energy consumption, and is highly safe. It has broad prospects in industrial applications for capturing trace noble gases. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is the PXRD pattern of the material obtained in Example 1.
[0018] Figure 2 This is the nitrogen adsorption-desorption isotherm of the material obtained in Example 1 at 77K.
[0019] Figure 3These are the single-component adsorption isotherms of Kr, N2, Ar and O2 at 298K for the material obtained in Example 1 and commercial molecular sieves 4A, 5A and 13X.
[0020] Figure 4 The figure is a comparison of the krypton adsorption performance of the material obtained in Example 1 and commercial molecular sieves 4A, 5A and 13X.
[0021] Figure 5 This is the dynamic penetration curve of the material obtained in Example 1 for a mixture of 500 ppm krypton gas and air at room temperature.
[0022] Figure 6 This is the dynamic desorption curve of the material obtained in Example 1 at room temperature.
[0023] Figure 7 This is the dynamic penetration cycle of the material obtained in Example 1 to a mixture of 500 ppm krypton and air at room temperature.
[0024] Figure 8 This is the dynamic breakthrough curve of commercial molecular sieve for 500ppm krypton and air mixture at room temperature.
[0025] Figure 9 This is the penetration curve of the material obtained in Example 1 for a mixture of 500 ppm krypton and air at room temperature and high relative humidity.
[0026] Figure 10 The material obtained in Example 1 was subjected to a dynamic permeation cycle of a 500 ppm krypton and air mixture at room temperature and high relative humidity. DETAILED DESCRIPTION
[0027] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.
[0028] Example 1
[0029] ① Place 26.005g of tetrabutylammonium hydroxide, 23.6g of tetrabutylammonium silicate and 8.9g of deionized water in a 100mL polytetrafluoroethylene liner and stir continuously at room temperature for 12 hours to fully mix the reactants.
[0030] ② The reaction mixture was sealed in a reactor and placed in an oven at 170°C for 3 days.
[0031] ③ After cooling, the synthesized sample was centrifuged and washed with deionized water three times, and then dried in an oven at 80°C overnight.
[0032] ④ Place the dried sample in a muffle furnace, heat it to 550°C at a heating rate of 2°C per minute, and calcine it in an air atmosphere at 550°C for 10 hours, then cool it to 25°C to obtain pure silicon ZSM-11 molecular sieve.
[0033] Depend on Figure 1 It can be seen that the prepared molecular sieve corresponds to the simulated peak of the corresponding configuration, proving that the pure silicon molecular sieve sample was successfully synthesized, and the nitrogen adsorption isotherm at 77K shows that the material has permanent porosity.
[0034] Adsorption process experiment 1:
[0035] ① Single-component adsorption experiments of krypton, nitrogen, argon and oxygen were carried out at 298K.
[0036] ②The single-component Langmuir model was used to fit and calculate the IAST selectivity of ZSM-11 and commercial molecular sieves 4A, 5A, and 13X for Kr / N2 (50 / 50, v / v) at 298K.
[0037] from Figure 3-4 It can be seen that the material obtained from Example 1 has a greater difference in the adsorption amount of Kr and air components than commercial molecular sieves 4A, 5A and 13X, and the calculated IAST selectivity proves its potential for capturing trace amounts of Kr in the air.
[0038] Separation process experiment 2:
[0039] The application test of trapping trace krypton gas under dry conditions was carried out using molecular sieve as adsorbent:
[0040] ① Take an appropriate amount of molecular sieve material to prepare 40-60 mesh particles, and then fill them into a Φ4.6×150mm adsorption column.
[0041] ② Before conducting the first penetration experiment, use helium to purge the adsorption column for several hours at an appropriate temperature to completely remove the guest molecules from the material.
[0042] ③ After the purge is completed, cool it naturally to room temperature, and pass a mixture of 500 ppm krypton and air into the adsorption column at room temperature, setting the flow rate to 3.5 mL / min.
[0043] ④ Analyze the outflow components at the outlet using mass spectrometry.
[0044] ⑤The content of the sampling components was analyzed, and finally the penetration curves of krypton and air were obtained.
[0045] ⑥ After each separation operation is completed, the adsorption column is regenerated by in-situ purge with helium at room temperature for 30 minutes, and then the next penetration cycle is repeated. At the same time, the component content is detected at the outlet and the desorption curve is drawn.
[0046] Depend on Figure 5 It can be seen that pure silicon ZSM-11 has the longest Kr retention time, followed by pure silicon SSZ-13, and has excellent performance in separating trace Kr from air. Figure 6 It can be seen that in the desorption stage, both pure silicon molecular sieves can be enriched to obtain krypton gas with a purity greater than 85%. Figure 7 The separation time of the five penetration cycles remained basically the same, proving that the material has good cyclic stability. Figure 8 It can be seen that pure silicon ZSM-11 and SSZ-13 materials have better separation performance of trace Kr from air than commercial molecular sieves 4A, 5A, and 13X.
[0047] Separation process experiment 3:
[0048] The application test of trapping trace krypton gas under humid conditions was carried out using molecular sieve as adsorbent:
[0049] ① Take an appropriate amount of molecular sieve material to prepare 40-60 mesh particles, and then fill them into a Φ4.6×150mm adsorption column.
[0050] ② Before conducting the first penetration experiment, use helium to purge the adsorption column for several hours at an appropriate temperature to completely remove the guest molecules from the material.
[0051] ③ After the purge is completed, the mixture is naturally cooled to room temperature. A mixture of 500 ppm krypton gas and air is first introduced into a saturated sodium chloride solution at room temperature and then into the adsorption column. The flow rate is set to 3.5 mL / min.
[0052] ④ Analyze the outflow components at the outlet using mass spectrometry.
[0053] ⑤The content of the sampling components was analyzed, and finally the penetration curves of krypton and air were obtained.
[0054] ⑥ After each separation operation is completed, the adsorption column is regenerated by purging with helium in situ at room temperature for 30 minutes, and then the next penetration cycle is repeated.
[0055] Figure 9-10 It can be seen that the pure silicon ZSM-11 material can still maintain its performance in capturing trace krypton gas even under high relative humidity conditions and retains excellent cycle stability, demonstrating its potential for capturing trace krypton gas in actual humid conditions. Figure 5 、 Figure 9 It can be seen that compared with a dry environment, a humid environment will not increase the krypton gas separation time.
[0056] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.
Claims
1. An application of using pure silicon molecular sieve to efficiently capture trace krypton gas under humid conditions, characterized in that: The pure silicon molecular sieve is a pure silicon molecular sieve ZSM-11 of MEL configuration; the relative humidity range of the humid environment is 0-75%; the pure silicon molecular sieve can realize adsorption separation of krypton gas and air mixture.
2. The use of pure silicon molecular sieve to efficiently capture trace amounts of krypton gas under humid conditions as claimed in claim 1, characterized in that: The pure silicon molecular sieve in a humid environment will not substantially increase the krypton gas separation time compared to a dry environment.
3. The use of pure silicon molecular sieve to efficiently capture trace amounts of krypton gas under humid conditions as claimed in claim 1, characterized in that: The pure silicon molecular sieve can be enriched to obtain krypton gas with a purity greater than 85%.
4. The use of pure silicon molecular sieve to efficiently capture trace amounts of krypton gas under humid conditions as claimed in claim 1, characterized in that: At 298K and 1 bar, the Kr adsorption capacity is greater than 12 cm 3 / g, Kr / N2 selectivity is greater than 4.
5. The use of pure silicon molecular sieve to efficiently capture trace amounts of krypton gas under humid conditions as claimed in claim 1, characterized in that: Pure silicon molecular sieve still has good dynamic penetration effect under the condition of relative humidity as high as 72.6%.
6. The use of pure silicon molecular sieve for efficiently capturing trace amounts of krypton gas under humid conditions as claimed in claim 1, characterized in that: The pure silicon molecular sieve can be applied to monitoring trace amounts of radioactive noble gas Kr.
7. The use of pure silicon molecular sieve for efficiently capturing trace amounts of krypton gas under humid conditions as claimed in claim 1, characterized in that: The synthesis method of pure silicon molecular sieve ZSM-11 is as follows: tetrabutylammonium hydroxide, tetrabutylammonium silicate and distilled water are mixed in a reaction kettle, stirred to fully dissolve, sealed and reacted at 155-175°C. After the reaction is completed, the reaction product is washed, dried and calcined to obtain pure silicon molecular sieve ZSM-11.
8. The use of pure silicon molecular sieve for efficiently capturing trace amounts of krypton gas under humid conditions as claimed in claim 7, characterized in that: The mass ratio of tetrabutylammonium hydroxide to tetrabutylammonium silicate is 1-1.2:1; the amount of distilled water added is 15-25% of the total mass of tetrabutylammonium hydroxide and tetrabutylammonium silicate; the calcination conditions are a heating rate of 2°C / min, heating to 500-550°C, and a calcination time of 6-12 hours.
9. The use of pure silicon molecular sieve for efficiently capturing trace amounts of krypton gas under humid conditions as claimed in claim 5, characterized in that: The operating conditions of the dynamic penetration are: the adsorption column size is 4.6×150 mm, the mixed gas flow rate is 3.5 mL / min, and the regeneration purge time is less than 30 min.