Metal ion modified molecular sieve for adsorbing and purifying electronic gas helium as well as preparation method and application of metal ion modified molecular sieve

Abstract

The invention discloses a metal ion modified molecular sieve for adsorbing and purifying electronic gas helium as well as a preparation method and application of the metal ion modified molecular sieve. The synthesis method comprises the following steps: adding SSZ-13 molecular sieve powder into a metal salt aqueous solution, stirring at a second preset temperature for a second preset time, filtering with water, and drying to obtain the metal ion modified SSZ-13 molecular sieve material. The SSZ-13 molecular sieve material with proper pore diameter and strong pore surface polarity is prepared by performing accurate metal ion exchange on the SSZ-13 molecular sieve, and the SSZ-13 molecular sieve material not only has relatively high adsorption capacity on neon, but also has very low adsorption capacity on helium. Therefore, the material can preferentially and selectively adsorb neon in helium, and the purpose of producing high-purity helium can be achieved.

Description

Technical Field

[0001] The present invention relates to the field of gas adsorption separation materials, and particularly to a metal ion-modified molecular sieve for adsorbing and purifying electronic gas helium, and a preparation method and application thereof. Background Art

[0002] In industrial and special fields, both helium and neon play key roles. As an extremely important non-renewable rare strategic resource, helium is widely used in many fields such as semiconductors, aerospace, medical, aviation, and optoelectronic product production. Neon is a rare inert gas and is generally used as an important filling medium in neon lamps, mercury lamps, and the electronics industry, and can also be used as a cryogenic coolant, special mixed gas, etc.

[0003] At present, helium extraction from natural gas and air separation units is the main way to obtain helium. Inevitably, trace amounts (dozens of ppm, helium extraction from natural gas) or large amounts (30% - 75%, helium extraction from air separation units) of neon will be doped in the helium obtained by these two methods. With the increasing demand for high-purity rare gas helium in fields such as semiconductor integrated circuits year by year, it is necessary to develop separation methods suitable for different ratios of helium-neon mixed gas to obtain high-purity helium for industrial production.

[0004] Due to the extremely similar physical and chemical properties of Ne and He, such as boiling points (He: 4.30K; Ne: 27.07K), kinetic diameters (He: Ne: ) and polarizabilities (He: 2.05×10 25 / cm 3 ; Ne: 3.96×10 25 / cm 3 ), the currently commonly used gas separation technologies such as cryogenic distillation, membrane separation, and pressure swing adsorption have poor effects in removing trace neon in helium. And the separation of helium-neon mixed gas by distillation method needs to be carried out in the ultra-low temperature region (4.3K - 27.07K), with extremely high energy consumption. Therefore, in order to reduce energy consumption and improve separation efficiency, it is necessary to develop separation and purification technologies in a relatively high temperature region (such as from the near liquid helium temperature region of 4.3K to the liquid nitrogen temperature region of 77.3K).

[0005] As a simple and efficient separation method, the adsorption method is favored by scientists. Using the adsorption process to separate gases has the advantages of low cost, simple equipment, easy operation, high efficiency, environmental protection, and recyclable materials.

[0006] The core of the adsorption method is the adsorbent. At the liquid nitrogen temperature range, traditional adsorbent materials such as activated carbon or carbon molecular sieve adsorbents have weak adsorption capacity for neon gas and small adsorption amounts, making it difficult to meet the requirements for removing trace neon gas in helium and for the neon removal adsorbent in a helium-neon separation system with medium neon content; therefore, there is an urgent need to develop a more efficient adsorbent for extracting / separating neon gas from helium. Summary of the Invention

[0007] In order to overcome the deficiencies of the prior art, the present invention provides an easily synthesized adsorption separation material, which realizes enhanced adsorption of trace / large amounts of neon gas in helium at the liquid nitrogen temperature range (77.3K), and solves the technical problems of poor deep removal / effect of trace / large amounts of neon gas in helium in the processes of helium extraction from natural gas and air separation units. Specifically, it is a metal ion modified molecular sieve for adsorbing and purifying electronic gas helium, its preparation method and application. The synthesis method of the adsorption material is to introduce metal cations to adjust the surface chemical properties and pore size of the SZZ-13 molecular sieve pores to achieve the separation of helium / neon gas.

[0008] The object of the present invention is achieved through the following technical solutions: A metal ion modified molecular sieve for adsorbing and purifying electronic gas helium and its preparation method, including the following steps:

[0009] (1) Place the SSZ-13 molecular sieve powder in a muffle furnace for activation, that is, calcine at a first preset temperature for a first preset time to obtain the activated SSZ-13 powder;

[0010] (2) Add the metal salt to the aqueous solution and stir at a second preset temperature for a second preset time to obtain a metal salt solution;

[0011] (3) Add the activated SSZ-13 molecular sieve powder to the metal salt aqueous solution, stir at a third preset temperature for a third preset time, filter with water, and dry to obtain the metal ion modified SSZ-13 molecular sieve. Among them, the metal ion modified SSZ-13 molecular sieve includes SSZ-13 molecular sieve and metal cations, and the metal cations are adsorbed in the pores of the SSZ-13 molecular sieve. By mass ratio, SSZ-13 molecular sieve: metal ions = 100:0.18 - 2.8.

[0012] The SSZ-13 molecular sieve is an artificially synthesized microporous molecular sieve with a chabazite (CHA) structure. The SSZ-13 molecular sieve contains a unique small pore, large cage structure and a three-dimensional eight-membered ring pore system. The diameter value of the CHA cage is The corresponding pore opening diameter size is Its specific surface area can reach up to 800m 2 / g. By replacing the balancing cations outside its framework, its pore size and the chemical properties of the inner surface of the pore channels can be adjusted, enhancing its shape selectivity and separation ability for mixtures, and thus it is widely used in the fields of gas separation and petrochemical industry.

[0013] The technical solution of the present invention replaces the H in the SSZ-13 molecular sieve with large-sized metal cations + , where the polarizability of the metal cations is greater than that of hydrogen ions, which can increase the electric field strength inside the pore channels of the SSZ-13 molecular sieve, thereby strengthening the van der Waals force between the molecular sieve and neon gas, and further enhancing the adsorption amount of neon gas by the molecular sieve under low pressure, and improving the helium-neon separation selectivity to meet the requirement of deep removal of trace neon gas in helium gas; at the same time, by precisely controlling the pore volume and pore size of the SSZ-13 molecular sieve, its adsorption capacity for neon gas under higher pressure can be improved, and further meet the requirements of the helium-neon separation system containing medium neon content for the neon-removing adsorbent. Since the polarizability of helium gas is lower than that of neon gas, introducing an appropriate amount of metal ions will not significantly increase the adsorption amount of helium gas. A metal ion-modified molecular sieve obtained by using the synthesis method provided by the present invention can respectively adsorb and remove trace / large amounts of neon gas in helium gas, thereby realizing the separation and purification of mixed gases with different helium-neon ratios in the processes of helium extraction from natural gas and helium extraction from air separation units, and achieving the purpose of producing high-purity helium gas (6N grade) in a relatively high temperature range (77.3K).

[0014] Preferably, in step (2), the metal ion in the metal salt is Li + , Na + , K + , Ag + , Ca 2+ , Co 2+ , Ni 2+ , Cu 2+ One of them. Using the above metal ion modification can obtain a metal ion-modified molecular sieve with better ability to separate and purify helium gas.

[0015] Preferably, in step (2), the concentration of the metal salt aqueous solution is 0.005 - 1.0 mol / L, preferably 0.005 - 0.1 mol / L. In step (3), the concentration of the SSZ-13 molecular sieve powder in the metal salt solution is 0.001 - 0.05 g / ml, preferably 0.001 - 0.01 g / mL. If the amount of metal ions is too small or too large, it will affect the adsorption effect of the adsorbent material on neon gas, and the above dosage can be proved to be more suitable through experimental data. More preferably, the addition amount of the SSZ-13 molecular sieve powder is 0.006 g / mL, and the concentration of the metal salt aqueous solution is 0.05 mol / L.

[0016] Preferably, in step (1), the first preset temperature is 500°C to 650°C, preferably 550°C; the first preset time is 3 to 7 hours, and the heating and cooling rates of the muffle furnace are 1 to 5°C / min, and it is cooled to 25 to 35°C.

[0017] Preferably, in step (2), the second preset temperature is 30 - 50°C, and the second preset time is 10 to 50 minutes, preferably 30 to 40 minutes.

[0018] Preferably, in step (3), the third preset temperature is 30 to 90°C, and the third preset time is 3 to 24 hours, preferably 5 to 8 hours.

[0019] Preferably, in step (3), the drying operation includes:

[0020] The filtered product is heated to 100 - 110°C at a rate of 5°C / min, maintained at this temperature for 2 h, then heated to 195 - 205°C at a rate of 5°C / min, maintained at this temperature for 5 h, and then cooled to 25 - 30°C at a rate of 5°C / min. The settings of the heating rate, temperature, and time in the drying operation remove most of the water in the synthesized material, making the synthesized adsorbent material more stable.

[0021] Preferably, in step (3), the modified SSZ-13 zeolite is filtered with sufficient water to avoid the attachment of metal salt aqueous solution on the material surface and reduce the adsorption performance. More preferably, the mass ratio of zeolite to water is 1:200.

[0022] The present invention also provides a metal ion modified zeolite obtained by the synthesis method according to any one of the above. The metal ion modified zeolite provided by the present invention has high separation performance for helium / neon.

[0023] The present invention also provides a synthesis method of a metal ion modified zeolite. The metal ion modified zeolite includes SSZ-13 zeolite and metal cations; the metal ions are one of Li + 、Na + 、K + 、Ag + 、Ca 2+ 、Co 2+ 、Ni 2+ 、Cu 2+ ; the metal cations are adsorbed in the pores of the SSZ-13 zeolite. By mass ratio, SSZ-13 zeolite: metal cations = 100: 0.18 - 2.8. More preferably, SSZ-13 zeolite: metal cations = 100: 0.36 - 1.79.

[0024] The present invention also provides an application of a metal ion-modified molecular sieve for adsorptive purification of electronic gas helium.

[0025] In the present invention, metal ion modification can increase the electric field strength in the pores of the SSZ-13 molecular sieve, thereby increasing the polarization force between the molecular sieve and neon gas, further enhancing the adsorption amount of neon gas by the molecular sieve in the helium-neon mixed gas, and improving the extraction rate of neon gas.

[0026] In the application of the metal ion-modified molecular sieve provided by the present invention in the adsorptive purification of electronic gas helium, 1 g of the metal ion-modified molecular sieve is used to treat 70 - 120 mL of the crude neon gas / helium gas, where the ratio of neon gas / helium gas in the crude gas is 1:9999 (v / v) or 1:1 (v / v), and the pressure is 1 standard atmosphere.

[0027] The mechanism of the present invention is as follows:

[0028] Introducing metal cations into the pores of the SSZ-13 molecular sieve in the present invention can further increase the electric field strength in the pores of the molecular sieve, thereby enhancing the van der Waals force between the molecular sieve and neon gas, and further enhancing the adsorption amount of neon gas by the molecular sieve under low pressure / medium pressure; at the same time, since the polarizability of helium gas is low, introducing metal ions will not significantly enhance the adsorption amount of helium gas, so that the selectivity of helium-neon separation remains at an extremely high level. When the adsorbent material provided by the present invention is used to remove trace / large amounts of neon gas in helium gas, it enhances the adsorption amount and selectivity of neon gas, increases the yield of electronic-grade high-purity helium gas (6N) obtained per unit mass of the adsorbent, and realizes cost reduction and efficiency improvement.

[0029] The present invention has the following advantages and effects compared with the prior art:

[0030] (1) The adsorption separation method used in the present invention can solve the bottleneck that traditional adsorbents in the natural gas helium extraction process have low selectivity for neon gas and it is difficult to achieve deep removal (reduce impurities to below 1 ppm), and it raises the separation temperature to a higher temperature range, with low energy consumption and simple operation.

[0031] (2) The adsorption separation method used in the present invention can solve the bottleneck that traditional adsorbents in the helium extraction process of air separation units have low adsorption capacity for neon gas and it is difficult to achieve both high selectivity and high adsorption amount, and it raises the separation temperature to a higher temperature range, with low energy consumption and simple operation.

[0032] (3) The SSZ-13 molecular sieve used in the present invention has a wide range of raw material sources and low synthesis costs, and has been widely used in industrial catalysis and separation; the preparation method of the metal ion modification described in the present invention has mild conditions and has great industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1Adsorption isotherm of neon / helium on the Ag-SSZ-13 zeolite material synthesized in Example 1 (77.3 K, 101.325 kPa). Detailed implementation manners

[0034] The present invention will be further described in detail with reference to specific embodiments below, but the implementation manners of the present invention are not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0035] In the following description, technical solutions are elaborated in combination with specific illustrations to fully understand the present invention application. However, the present invention application can be implemented in many other ways different from those described herein. Similar extended embodiments made by those of ordinary skill in the art without creative efforts all fall within the scope of protection of the present invention.

[0036] Example 1

[0037] An Ag + modified SSZ-13 zeolite, and its synthesis method is as follows:

[0038] The SSZ-13 zeolite was heated to 550 °C at a rate of 2 °C / min, maintained at this temperature for 5 hours, and then cooled to 100 °C at a rate of 10 °C / min to obtain the activated SSZ-13 zeolite.

[0039] Take 0.3 g of the activated SSZ-13 zeolite, add it to 50 mL of 0.05 mol / L silver nitrate aqueous solution, react at 50 °C for 5 hours, wash and filter the product obtained after the reaction with deionized water. The filtered material was heated to 100 °C at a rate of 5 °C / min in a muffle furnace, maintained at this temperature for 2 hours, then heated to 200 °C at a rate of 5 °C / min, maintained at this temperature for 4 hours, and then cooled to 30 °C at a rate of 5 °C / min. The obtained material was denoted as 0.05-Ag-SSZ-13#.

[0040] Example 2

[0041] A Li + modified SSZ-13 zeolite, and its synthesis method is as follows:

[0042] Take 0.3 g of activated ZSM-5 molecular sieve and add it to 50 mL of 0.05 mol / L lithium chloride aqueous solution. React at 70 °C for 3 hours. Wash and filter the product obtained after the reaction with deionized water. The filtered material is heated in a muffle furnace to 100 °C at a rate of 5 °C / min, maintained at this temperature for 2 hours, then heated to 200 °C at a rate of 5 °C / min, maintained at this temperature for 4 hours, and then cooled to 30 °C at a rate of 5 °C / min. The obtained material is denoted as 0.05-Li-SSZ-13#.

[0043] Among them, the activation process of the SSZ-13 molecular sieve is the same as that in Example 1.

[0044] Example 3

[0045] A kind of Ni 2+ Modified SSZ-13 molecular sieve, and its synthesis method is as follows:

[0046] Take 0.3 g of activated SSZ-13 molecular sieve and add it to 50 mL of 0.05 mol / L nickel chloride hexahydrate aqueous solution. React at 30 °C for 24 hours. Wash and filter the product obtained after the reaction with deionized water. The filtered material is heated in a muffle furnace to 100 °C at a rate of 5 °C / min, maintained at this temperature for 2 hours, then heated to 200 °C at a rate of 5 °C / min, maintained at this temperature for 4 hours, and then cooled to 30 °C at a rate of 5 °C / min. The obtained material is denoted as 0.05-Ni-SSZ-13#.

[0047] Among them, the activation process of the SSZ-13 molecular sieve is the same as that in Example 1.

[0048] Example 4

[0049] A kind of Co 2+ Modified SSZ-13 molecular sieve, and its synthesis method is as follows:

[0050] Take 0.3 g of activated SSZ-13 molecular sieve and add it to 50 mL of 0.05 mol / L cobalt nitrate aqueous solution. React at 65 °C for 4 hours. Wash and filter the product obtained after the reaction with deionized water. The filtered material is heated in a muffle furnace to 100 °C at a rate of 5 °C / min, maintained at this temperature for 2 hours, then heated to 200 °C at a rate of 5 °C / min, maintained at this temperature for 4 hours, and then cooled to 30 °C at a rate of 5 °C / min. The obtained material is denoted as 0.05-Co-SSZ-13#.

[0051] Among them, the activation process of the SSZ-13 molecular sieve is the same as that in Example 1.

[0052] Example 5

[0053] A Ca 2+ Modified SSZ-13 molecular sieve, and its synthesis method is as follows:

[0054] Take 0.3 g of activated SSZ-13 molecular sieve, add it to 50 mL of 0.05 mol / L calcium chloride aqueous solution, react at 80 °C for 7 hours, wash and filter the product obtained after the reaction with deionized water, and heat the filtered material in a muffle furnace to 100 °C at a rate of 5 °C / min, keep it at this temperature for 2 hours, then heat it to 200 °C at a rate of 5 °C / min, keep it at this temperature for 4 hours, and then cool it to 30 °C at a rate of 5 °C / min. The obtained material is denoted as 0.05-Ca-SSZ-13#.

[0055] Among them, the activation process of the SSZ-13 molecular sieve is the same as that in Example 1.

[0056] To illustrate the superiority of the present invention, the following comparative examples were also conducted. The following will conduct variable analysis based on Example 1.

[0057] Example 6

[0058] Compared with Example 1, in Example 6, before ion exchange, the SSZ-13 molecular sieve was not activated, and other reaction conditions were the same as those in Example 1.

[0059] Example 7

[0060] Compared with Example 1, in Example 7, the SSZ-13 molecular sieve was heated to 300 °C at a rate of 2 °C / min, kept at this temperature for 5 hours, and then cooled to 100 °C at a rate of 10 °C / min. Other reaction conditions were the same as those in Example 1. In this Comparative Example 2, the activation temperature was insufficient.

[0061] Example 8

[0062] Compared with Example 1, in Example 8, after Ag + exchange, the surface of the material was not washed with deionized water for the residual exchange solution, and other reaction conditions were the same as those in Example 1.

[0063] Example 9

[0064] Compared with Example 1, in Example 9, the Ag + modified SSZ-13 molecular sieve filtered with deionized water was not dried, and other reaction conditions were the same as those in Example 1.

[0065] Example 10

[0066] Example 10 is compared with Example 1. The amount of SSZ-13 molecular sieve is increased to 1 g, and other reaction conditions are the same as those in Example 1.

[0067] Example 11

[0068] Example 11 is compared with Example 1. The amount of SSZ-13 molecular sieve is reduced to 0.1 g, and other reaction conditions are the same as those in Example 1.

[0069] Example 12

[0070] Example 12 is compared with Example 1. The silver nitrate aqueous solution is increased to 1 mol / L, and other reaction conditions are the same as those in Example 1.

[0071] Example 13

[0072] Example 13 is compared with Example 1. The silver nitrate aqueous solution is reduced to 0.001 mol / L, and other reaction conditions are the same as those in Example 1.

[0073] The materials obtained from the above synthesis are subjected to relevant tests, and the results are as follows.

[0074] In this application, a 3-Flex all-functional multi-purpose adsorption instrument produced by Micromeritics Company in the United States is used to characterize the neon and helium gas adsorption properties of the materials obtained in the examples and comparative examples of the present invention. The static adsorption isotherm of the material at 77.3 K is tested by the volumetric method. Figure 1 It is the adsorption isotherm of the Ag-SSZ-13# molecular sieve material obtained in Example 1 for neon / helium at 77.3 K and 101.325 kPa. It can be analyzed from the figure that while the material shows a low adsorption amount of helium, the isotherm of neon in the low-pressure region is still very steep. The adsorption amount of neon at 10 kPa is 0.800 mmol / g, and the helium-neon separation selectivity (calculated by the ratio of gas adsorption amounts) is 65.57. The adsorption amount of neon at 101.325 kPa is 4.686 mmol / g, and the helium-neon separation selectivity (calculated by the ratio of gas adsorption amounts) is 33.47, which proves its ability to extract high-purity helium from the neon / helium mixture gas.

[0075] The adsorption materials synthesized in the above Examples 1 to 13 are applied to the adsorption of neon and helium, and the adsorption effects are shown in Table 1

[0076] Table 1 Neon and helium adsorption amounts and adsorption separation ratios of each material under the conditions of 77.3 K and 101.325 kPa

[0077] Material Ne adsorption amount (mmol / g) He adsorption amount (mmol / g) Ne / He adsorption separation ratio Example 1 4.686 0.140 33.471 Example 2 3.934 0.617 6.376 Example 3 3.955 0.554 7.139 Example 4 4.093 0.613 6.677 Example 5 3.350 0.707 4.738 Example 6 1.152 0.407 2.830 Example 7 1.314 0.563 2.334 Example 8 2.057 0.504 4.081 Example 9 2.036 0.549 3.709 Example 10 4.031 0.543 7.424 Example 11 3.975 0.589 6.749 Example 12 2.862 0.358 7.994 Example 13 3.328 0.387 8.599

[0078] It can be seen from Table 1 above that Example 1 is a better synthesis scheme.

[0079] It can be seen from the comparison between Examples 6 and 7 and Example 1 that if the SSZ-13 molecular sieve is not activated or the activation temperature is too low, the template agent in the molecular sieve cannot be removed sufficiently, which will hinder the + entry of Ag into the pore channels of the molecular sieve to undergo a displacement reaction with hydrogen atoms, resulting in a decrease in the Ne / He adsorption separation ratio.

[0080] It can be seen from the comparison between Example 8 and Example 1 that when Example 8 does not use deionized water to wash the residual exchange solution on the material surface, the pore channels on the material surface are blocked, resulting in a low adsorption amount of the target component Ne by the material and a decrease in the Ne / He adsorption separation ratio.

[0081] It can be seen from the comparison between Example 9 and Example 1 that when Example 9 does not dry the Ag + modified SSZ-13 molecular sieve filtered with deionized water, most of the pore channels of the molecular sieve are occupied by water, resulting in a low adsorption amount of the target component Ne and a decrease in the Ne / He adsorption separation ratio.

[0082] It can be seen from the comparison between Examples 10 and 11 and Example 1 that when the dosage of SSZ-13 molecular sieve in Example 10 is increased to 1 g in Example 10, the ion exchange amount per unit material decreases, and the increase in the electric field strength in the pore channels is not obvious. Therefore, the adsorption amount of the target component Ne decreases; when the dosage of SSZ-13 molecular sieve in Example 11 is reduced to 0.1 g, the ion exchange amount per unit material increases, and the electric field strength in the pore channels increases, but introducing too many large-size metal ions will block the pore channels, resulting in a decrease in the adsorption amount of the target component Ne. Thus, an appropriate dosage of SSZ-13 molecular sieve can enable it to obtain an appropriate content of metal ions, and the prepared material has a high adsorption amount of the target component Ne while maintaining a low adsorption amount of He.

[0083] It can be seen from the comparison between Examples 12 and 13 and Example 1 that when the silver nitrate aqueous solution in Example 12 is increased to 1 mol / L, the pore channels of the material are significantly reduced. At this time, even if there are more silver ions in the pore channels, due to the decrease in the pore volume, the adsorption amount of the target component Ne by the material is very low; when the silver nitrate aqueous solution in Example 13 is reduced to 0.001 mol / L, the pore diameter of the material does not shrink significantly and there are fewer silver ions in the pore channels, and the electric field strength in the pore channels of the molecular sieve is low, resulting in a decrease in the adsorption of the target component Ne. Thus, an appropriate silver nitrate solution can introduce appropriate silver ions into the pore channels to interact with the target component without significantly reducing the pore volume of the material.

[0084] It should be understood that the detailed description of the technical solution of the present invention by means of the optimized embodiments above is illustrative rather than restrictive. It cannot be determined that the specific implementation manners of the present invention are limited thereto. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, modifying the technical solutions recorded in each embodiment or equivalently replacing some of the technical features should be regarded as falling within the scope of patent protection determined by the claims submitted for the present invention.

[0085] The above embodiments of the present invention are merely examples given for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a metal ion modified molecular sieve for adsorbing and purifying electronic gas helium, characterized in that: The following steps are involved: (1) placing the SSZ-13 molecular sieve powder in a muffle furnace for activation, i.e., calcining at a first preset temperature for a first preset time to obtain activated SSZ-13 powder; (2) adding a metal salt to the aqueous solution and stirring at a second preset temperature for a second preset time to obtain a metal salt solution; (3) adding the activated SSZ-13 molecular sieve powder to a metal salt aqueous solution, stirring at a third preset temperature for a third preset time, filtering with water, and drying to obtain a metal ion-modified SSZ-13 molecular sieve.

2. The metal ion modified molecular sieve for adsorbing and purifying electronic gas helium and the preparation method thereof according to claim 1, characterized in that: In step (2), the metal ion in the metal salt is Li + 、Na + , K + 、Ag + , Ca 2+ 、Co 2+ 、Ni 2+ , Cu 2+ One of them.

3. The metal ion modified molecular sieve for adsorbing and purifying electronic gas helium and the preparation method thereof according to claim 1, characterized in that: In step (2), the concentration of the aqueous metal salt solution is 0.005 to 1.0 mol / L.

4. The method for preparing Ag-SSZ-13 molecular sieve for adsorbing and purifying electronic gas helium according to claim 1, characterized in that: In step (3), the concentration of the SSZ-13 molecular sieve powder in the metal salt solution is 0.001 to 0.05 g / ml.

5. The method for preparing Ag-SSZ-13 molecular sieve for adsorbing and purifying electronic gas helium according to claim 1, characterized in that: In step (1), the first preset temperature is 500°C to 650°C, the first preset time is 3 to 7 hours, the heating and cooling rates of the muffle furnace are 1 to 5°C / min, and the temperature is lowered to 25 to 35°C.

6. The method for preparing Ag-SSZ-13 molecular sieve for adsorbing and purifying electronic gas helium according to claim 1, characterized in that: In step (2), the second preset temperature is 30-50° C., and the second preset time is 10 to 50 minutes.

7. The metal ion modified molecular sieve for adsorbing and purifying electronic gas helium and the preparation method thereof according to claim 1, characterized in that: In step (3), the third preset temperature is 30 to 90° C., and the third preset time is 3 to 24 hours.

8. The metal ion modified molecular sieve for adsorbing and purifying electronic gas helium and the preparation method thereof according to claim 1, characterized in that: In step (3), the drying operation includes: The filtered product was heated to 100-110°C at a rate of 5°C / min, maintained at this temperature for 2 hours, then heated to 195-205°C at a rate of 5°C / min, maintained at this temperature for 5 hours, and then cooled to 25-30°C at a rate of 5°C / min.

9. A metal ion modified molecular sieve prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The metal ion modified molecular sieve comprises SSZ-13 molecular sieve and metal cations, wherein the metal cations are adsorbed in the pores of the SSZ-13 molecular sieve; the metal ion is Li + 、Na + , K + 、Ag + , Ca 2+ 、Co 2+ 、Ni 2+ , Cu 2+ One of the above; the metal cations are adsorbed in the pores of the SSZ-13 molecular sieve, and the mass ratio is SSZ-13 molecular sieve: metal ion = 100: 0.18 to 2.

8.

10. Use of the metal ion-modified SSZ-13 molecular sieve according to claim 9 in the adsorption and purification of electronic gas helium.

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