Adsorbent for removing neon in helium as well as preparation method and application of adsorbent

Abstract

The invention belongs to the technical field of gas separation, and particularly relates to an adsorbent for removing neon in helium and a preparation method and application thereof.The preparation method comprises the steps that an aluminum source, sodium hydroxide and water are mixed and then stirred, then a template agent and a silicon source are added, stirring is conducted, and hydrogel is obtained; carrying out crystallization treatment on the hydrogel, and carrying out filtering, washing and drying treatment to obtain chabazite; the silica-alumina ratio of the chabazite is 3-5; the method comprises the following steps: carrying out ion exchange on chabazite and a metal salt solution, filtering, washing and drying to obtain the adsorbent. The adsorbent provided by the invention has a regular microporous structure and a strong electric field adsorption site, shows high selectivity and adsorption capacity for neon gas, and can realize removal of trace neon from helium gas.

Description

Technical Field

[0001] This invention belongs to the field of gas separation technology, specifically relating to an adsorbent for removing neon from helium, its preparation method, and its application. Background Technology

[0002] Helium, a non-renewable and scarce inert gas, plays an irreplaceable strategic role in high-tech fields such as low-temperature superconductivity, semiconductor manufacturing, aerospace, and nuclear magnetic resonance imaging due to its extremely low boiling point, excellent chemical stability, and high thermal conductivity. Helium is mainly extracted from natural gas or associated gases from oil and gas pipelines. These raw materials often contain various trace impurities, among which neon, due to its similar molecular size and boiling point to helium, is a difficult-to-remove impurity during helium refining. The presence of trace neon significantly reduces helium purity, thus affecting its application performance: in low-temperature superconducting systems, trace neon may cause a decrease in the cooling efficiency of superconducting equipment, increasing energy consumption and even triggering superconducting failure; in semiconductor processes, residual neon can lead to defects in chip circuits, reducing product yield; and in aerospace propulsion systems, it may affect propellant stability, posing a potential risk to flight safety.

[0003] Adsorption separation technology has become one of the main methods for removing trace amounts of neon due to its mild operating conditions, low energy consumption, and high separation efficiency. Currently, materials commonly used for neon adsorption mainly include zeolite molecular sieves (such as 13X) and activated carbon. However, 13X molecular sieves have limited adsorption capacity under low partial pressure conditions for neon and also exhibit some adsorption of helium, resulting in insufficient separation selectivity. While activated carbon materials have a high specific surface area, their uneven pore size distribution makes it difficult to control their separation selectivity for helium and neon. Furthermore, some materials are prone to structural collapse at low temperatures such as 77 K, making it difficult to meet the requirements for long-term stable operation. Summary of the Invention

[0004] In a first aspect, the present invention provides a method for preparing an adsorbent for removing neon from helium, comprising the following steps: (1) Mix aluminum source, sodium hydroxide and water and stir, then add template agent and silicon source and stir to obtain hydrogel; the composition of the hydrogel is Na2O:Al2O3:SiO2:template agent:H2O=2:(2~4):(35~45):(10~20):(150~300) in molar ratio. (2) The hydrogel is crystallized, filtered, washed and dried to obtain chabazite; the silica-alumina ratio of the chabazite is 3~5; (3) The adsorbent is obtained by ion exchange between zeolite and metal salt solution, followed by filtration, washing and drying.

[0005] This invention achieves effective adsorption of neon gas by rationally controlling the composition of the hydrogel (i.e., the ratio of aluminum source, sodium hydroxide, template agent, silicon source and water) and regulating the ion exchange parameters, so that the zeolite formed after hydrogel crystallization can have a regular microporous structure and adsorption sites after ion exchange.

[0006] In some preferred embodiments, the composition of the hydrogel, in molar ratio, is Na2O:Al2O3:SiO2:template:H2O=2:(2~4):(38~42):(14~18):(220~230).

[0007] In some preferred embodiments, the composition of the hydrogel, in molar ratio, is Na2O:Al2O3:SiO2:template:H2O = 2:4:(38~42):(14~18):(220~230).

[0008] In some preferred embodiments, the hydrogel is composed of Na2O:Al2O3:SiO2:template:H2O in a molar ratio of 2:4:40:16:224.

[0009] The hydrogel has a better adsorption effect when its composition is within the above-mentioned preferred range.

[0010] In some embodiments, the aluminum source includes at least one of aluminum hydroxide, aluminum powder, aluminum sulfate, and sodium aluminate.

[0011] In some embodiments, the template agent comprises N,N,N-trimethyl-1-adamantyl ammonium hydroxide.

[0012] In some embodiments, the silicon source includes at least one of silica sol, silica gel, and diatomaceous earth.

[0013] In some embodiments, the crystallization treatment is performed at a temperature of 150-170°C for 3-5 days.

[0014] In some preferred embodiments, the silica-alumina ratio of the chabazite is 3.

[0015] In some embodiments, the concentration of the metal salt solution is 0.5~1.5 mol / L.

[0016] In some embodiments, the metal salt includes barium chloride.

[0017] In some embodiments, the ion exchange temperature is 70-90°C, the ion exchange time is 8-16 hours, and the ion exchange is performed 2-4 times.

[0018] In a second aspect, the present invention provides an adsorbent for removing neon from helium, which is prepared by the method described above.

[0019] In a third aspect, the present invention provides an adsorption device for removing neon from helium gas, comprising the aforementioned adsorbent. Compared with the prior art, the present invention has the following beneficial effects: The adsorbent provided by this invention has a regular microporous structure and strong electric field adsorption sites, exhibiting high selectivity and adsorption capacity for neon gas, and can remove trace amounts of neon from helium gas. Moreover, the preparation process is simple and suitable for industrial production. Attached Figure Description

[0020] Figure 1 The XRD patterns are those of the adsorbents obtained in Examples 1-2 and Comparative Examples 4-5.

[0021] Figure 2 The graphs show the isothermal pressure swing adsorption tests of the adsorbents obtained in Examples 1-2 and Comparative Examples 1-5 at 77 K (liquid nitrogen bath) with high-purity neon gas (99.999%).

[0022] Figure 3 The image shows the separation effect of the adsorbent obtained in Example 1 on a two-component mixed gas at 77 K. Detailed Implementation

[0023] The following detailed embodiments further illustrate the content of the present invention. These embodiments do not constitute a limitation on the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the concept of the present invention still fall within the scope of protection of the present invention. The raw materials, reagents, or devices used in the embodiments are all available from conventional commercial sources or can be obtained through existing technical methods. Unless otherwise specified, the experimental or testing methods are conventional methods in the art.

[0024] Example 1 This embodiment provides an adsorbent for removing neon from helium, and its preparation method includes the following steps: (1) Using 40% silica sol as the silicon source, Al(OH)3 as the aluminum source, NaOH as the alkali source, and TMAdaOH as the template agent, 0.48 g Al(OH)3, 0.22 g NaOH, and 11.78 g water were mixed and stirred for 1 h. Then, 8.92 g TMAdaOH was slowly added dropwise. After 1 h, 3.96 g silica sol was added and stirring was continued for another 1 h to obtain a hydrogel. The composition of the hydrogel, in molar ratio, was Na2O:Al2O3:SiO2:template agent:H2O = 2:4:40:16:224.

[0025] (2) The hydrogel was transferred into a hydrothermal reactor and heated at 160°C for 4 days. After filtration, washing and drying, chabazite was obtained. The silica-alumina ratio of the chabazite precursor was measured to be 3 by X-ray fluorescence spectroscopy.

[0026] (3) Add 5 g of chalcogenide precursor to 300 mL of BaCl2 aqueous solution (concentration of 1 mol / L), stir for 10 h in a water bath at 60 °C, repeat 3 times, then filter, wash with deionized water, and dry at 80 °C for 12 h to obtain the adsorbent used to remove neon from helium.

[0027] The adsorbent obtained in Example 1 was subjected to XRD analysis, and the results are as follows: Figure 1 As shown, the adsorbent is a zeolite molecular sieve with a chalcogenide crystal structure. The silica-to-alumina ratio of the adsorbent obtained in Example 1 was determined to be 3 using X-ray fluorescence spectroscopy (XRF).

[0028] Example 2 This embodiment provides an adsorbent for removing neon from helium, and its preparation method includes the following steps: (1) Using 40% silica sol as the silicon source, Al(OH)3 as the aluminum source, NaOH as the alkali source, and TMAdaOH as the template agent, 0.24 g Al(OH)3, 0.22 g NaOH, and 11.78 g water were mixed and stirred for 1 h. Then, 8.92 g TMAdaOH was slowly added dropwise. After 1 h, 3.96 g silica sol was added and stirring was continued for another 1 h to obtain a hydrogel. The composition of the hydrogel, in molar ratio, was Na2O:Al2O3:SiO2:template agent:H2O = 2:2:40:16:224.

[0029] (2) The hydrogel was transferred into a hydrothermal reactor and heated at 160°C for 4 days. After filtration, washing and drying, chabazite was obtained. The silica-alumina ratio of chabazite was determined to be 5 by X-ray fluorescence spectroscopy.

[0030] (3) Add 5 g of chalcogenide to 300 mL of BaCl2 aqueous solution (concentration of 1 mol / L), stir for 10 h in a water bath at 60 °C, repeat 3 times, then filter, wash with deionized water, and dry at 80 °C for 12 h to obtain the adsorbent used to remove neon from helium.

[0031] The adsorbent obtained in Example 2 was subjected to XRD analysis, and the results are as follows: Figure 1 As shown, the adsorbent is a zeolite molecular sieve with a chalcogenide crystal structure. The silica-to-alumina ratio of the adsorbent obtained in Example 2 was determined to be 5 using X-ray fluorescence spectroscopy (XRF).

[0032] Comparative Example 1 The comparative example used was commercially available 13X zeolite molecular sieve, purchased from Luoyang Jianlong Micro-Nano New Materials Co., Ltd.

[0033] Comparative Example 2 This comparative example uses commercially available NaY zeolite molecular sieves, purchased from Zibo Jiulong Chemical Technology Co., Ltd.

[0034] Comparative Example 3 The comparative example used was commercially available 5A zeolite molecular sieve, purchased from Luoyang Jianlong Micro-Nano New Materials Co., Ltd.

[0035] Comparative Example 4 This comparative example provides an adsorbent for removing neon from helium, and its preparation method includes the following steps: (1) Using 40% silica sol as the silicon source, Al(OH)3 as the aluminum source, NaOH as the alkali source, and TMAdaOH as the template agent, 0.12 g Al(OH)3, 0.22 g NaOH, and 11.78 g water were mixed and stirred for 1 h. Then, 8.92 g TMAdaOH was slowly added dropwise. After 1 h, 3.96 g silica sol was added and stirring was continued for another 1 h to obtain a hydrogel. The composition of the hydrogel, in molar ratio, was Na2O:Al2O3:SiO2:template agent:H2O = 2:1:40:16:224.

[0036] (2) The hydrogel was transferred into a hydrothermal reactor and heated at 160°C for 4 days. After filtration, washing and drying, chabazite was obtained. The silica-alumina ratio of chabazite was determined to be 10 by X-ray fluorescence spectroscopy.

[0037] (3) Add 5 g of chalcogenide to 300 mL of BaCl2 aqueous solution (concentration of 1 mol / L), stir for 10 h in a water bath at 60 °C, repeat 3 times, then filter, wash with deionized water, and dry at 80 °C for 12 h to obtain the adsorbent used to remove neon from helium.

[0038] The adsorbent obtained in Comparative Example 4 was subjected to XRD analysis, and the results are as follows: Figure 1 As shown, the adsorbent is a zeolite molecular sieve with a chalcogenide crystal structure. The silica-to-alumina ratio of the adsorbent obtained in Comparative Example 4 was determined to be 10 using X-ray fluorescence spectroscopy (XRF).

[0039] Comparative Example 5 This comparative example provides an adsorbent for removing neon from helium, and its preparation method includes the following steps: (1) Using 40% silica sol as the silicon source, Al(OH)3 as the aluminum source, NaOH as the alkali source, and TMAdaOH as the template agent, 0.06 g Al(OH)3, 0.22 g NaOH, and 11.78 g water were mixed and stirred for 1 h. Then, 8.92 g TMAdaOH was slowly added dropwise. After 1 h, 3.96 g silica sol was added and stirring was continued for another 1 h to obtain a hydrogel. The composition of the hydrogel, in molar ratio, was Na2O:Al2O3:SiO2:template agent:H2O = 2:0.5:40:16:224.

[0040] (2) The hydrogel was transferred into a hydrothermal reactor and heated at 160°C for 4 days. After filtration, washing and drying, chabazite was obtained. The silica-alumina ratio of chabazite was determined to be 16 by X-ray fluorescence spectroscopy.

[0041] (3) Add 5 g of chalcogenide to 300 mL of BaCl2 aqueous solution (concentration of 1 mol / L), stir for 10 h in a water bath at 60 °C, repeat 3 times, then filter, wash with deionized water, and dry at 80 °C for 12 h to obtain the adsorbent used to remove neon from helium.

[0042] The adsorbent obtained in Comparative Example 5 was subjected to XRD analysis, and the results are as follows: Figure 1 As shown, the adsorbent is a zeolite molecular sieve with a chalcogenide crystal structure. The silica-alumina ratio of the adsorbent obtained in Comparative Example 5 was determined to be 16 using X-ray fluorescence spectroscopy (XRF).

[0043] To verify the performance of the adsorbent obtained in this invention for removing neon from helium, the adsorbents obtained in each embodiment and comparative example were subjected to the following performance tests, with specific steps as follows: (1) Single-component performance test: Using a Micron 3FLEX physical adsorption instrument, the adsorbents obtained in the examples and comparative examples were activated in a vacuum environment at 300℃ for 10 h. After the temperature dropped to room temperature, isothermal pressure swing adsorption tests of high-purity neon (99.999%) were conducted at 77 K (liquid nitrogen bath). The results are as follows: Figure 2 As shown in Table 1, the amount of neon gas adsorbed at 0.1 bar was recorded.

[0044] Table 1 The results show that, comparing Examples 1-2 and Comparative Examples 1-3, the adsorbent provided by this invention exhibits a higher neon adsorption capacity compared to commercial zeolite molecular sieves (such as 13X, NaY, and 5A). Specifically, the neon adsorption capacity at 0.1 bar is ≥0.7 mmol / g, reaching as high as 1.6 mmol / g, demonstrating excellent adsorption performance. Comparing Examples 1-2 and Comparative Examples 4-5, the adsorbent provided by this invention requires reasonable control of the hydrogel composition (i.e., the ratio of aluminum source, sodium hydroxide, template agent, silicon source, and water) and regulation of ion exchange parameters during preparation. This ensures that the resulting zeolite, after crystallization and ion exchange treatment, possesses a regular microporous structure and adsorption sites, enabling effective neon adsorption.

[0045] (2) Multi-component performance testing: Multi-component test A: The adsorbent obtained in Example 1 was packed into a quartz fixed-bed adsorption column and activated under vacuum at 300°C for 2 hours before the test. A mixture of neon and helium (volume ratio of neon to helium 1:1) was introduced into the inlet of the adsorption column at a flow rate of 50 mL / min. The test temperature was 77 K (using a cryogenic bath cooled by liquid nitrogen). The neon in the outlet gas was detected by gas chromatography, and a breakthrough curve was plotted. The results are as follows: Figure 3 As shown.

[0046] The results show that in a neon / helium (1:1) mixture, helium molecules are hardly adsorbed at the beginning and pass directly through the adsorption bed, while the neon breakthrough curve remains at a near-zero baseline level for a long time. This means that the neon gas at the inlet is almost completely captured by the adsorbent, and the neon concentration in the outlet gas is extremely low. This indicates that the adsorbent provided by the present invention has a high dynamic adsorption capacity and selectivity for neon gas.

[0047] Multi-component test B: The adsorbent obtained in Example 1 was packed into a quartz fixed-bed adsorption column and activated under vacuum at 300°C for 2 hours before the test. A mixture of neon and helium (volume ratio of neon to helium 1:99) was introduced into the inlet of the adsorption column at a flow rate of 50 mL / min. The test temperature was 77 K (using a cryogenic bath cooled by liquid nitrogen). The neon in the outlet gas was detected by gas chromatography, and a breakthrough curve was plotted. The results are as follows: Figure 3 As shown.

[0048] The results show that in a neon / helium (1:99) mixture, the penetration curve representing neon remains at the baseline level for a considerable period of time, indicating that neon is completely and efficiently captured by the adsorbent, while helium passes through directly. This demonstrates that the adsorbent provided by this invention not only has a high adsorption capacity but also extremely high kinetic selectivity, which can meet the requirements for deep removal of trace impurities in industrial applications.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an adsorbent for removing neon from helium, characterized in that, Includes the following steps: (1) Mix aluminum source, sodium hydroxide and water and stir, then add template agent and silicon source and stir to obtain hydrogel; the composition of the hydrogel is Na2O:Al2O3:SiO2:template agent:H2O=2:(2~4):(35~45):(10~20):(150~300) in molar ratio. (2) The hydrogel is crystallized, filtered, washed and dried to obtain chabazite; the silica-alumina ratio of the chabazite is 3~5; (3) The adsorbent is obtained by ion exchange between zeolite and metal salt solution, followed by filtration, washing and drying.

2. The preparation method according to claim 1, characterized in that, The aluminum source includes at least one of aluminum hydroxide, aluminum powder, aluminum sulfate, and sodium aluminate.

3. The preparation method according to claim 1, characterized in that, The template agent includes N,N,N-trimethyl-1-adamantyl ammonium hydroxide.

4. The preparation method according to claim 1, characterized in that, The silicon source includes at least one of silica sol, silica gel, and diatomaceous earth.

5. The preparation method according to claim 1, characterized in that, The crystallization treatment temperature is 150~170℃, and the crystallization treatment time is 3~5 days.

6. The preparation method according to claim 1, characterized in that, The silica-alumina ratio of the chabazite is 3.

7. The preparation method according to claim 1, characterized in that, The concentration of the metal salt solution is 0.5~1.5 mol / L; the metal salt includes barium chloride.

8. The preparation method according to claim 1, characterized in that, The ion exchange temperature is 70~90℃, the ion exchange time is 8~16 h, and the ion exchange is performed 2~4 times.

9. An adsorbent for removing neon from helium, characterized in that, It is prepared by the method according to any one of claims 1 to 8.

10. An adsorption device for removing neon from helium, characterized in that, Includes the adsorbent as described in claim 9.

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