Method for simultaneously and efficiently removing b and p impurities in chlorosilane based on cu@zif-8 adsorbent

Abstract

The present application relates to a method for simultaneously and efficiently removing B and P impurities in chlorosilane based on Cu@ZIF-8 adsorbent, which comprises adding Cu@ZIF-8 adsorbent into liquid chlorosilane, sealing, and oscillating in an ice water bath for 1-4 hours to simultaneously and efficiently remove B and P impurities in chlorosilane, effectively solving the problem of difficult separation of B and P by distillation in chlorosilane, and exhibiting excellent adsorption performance in the removal of B and P impurities in chlorosilane, with a removal rate of B up to 80% and a removal rate of P up to 93%.

Description

TECHNICAL FIELD

[0001] The application relates to a method for simultaneously and efficiently removing B and P impurities in chlorosilane based on a Cu@ZIF-8 adsorbent, and belongs to the technical field of polysilicon. BACKGROUND

[0002] Chlorosilane is an important raw material for preparing polysilicon, and the impurities thereof are mainly brought in by industrial silicon powder, hydrogen, hydrogen chloride and equipment. The method for removing impurities in chlorosilane at home is mainly multi-stage rectification. Most metal impurities can be removed by using the multi-stage rectification method, but since the existence form of B and P impurities is complex and the chemical properties of B and P impurities are similar to those of chlorosilane, the rectification operation can only ensure the product quality through high reflux and high kettle discharge. The operation not only has low yield and unstable quality, but also has high energy consumption. If the content of B and P is high, the side reaction of B and P precipitation will occur at high temperature. The precipitated B and P will adhere to the silicon rod, which seriously affects the quality index of polysilicon. Therefore, a method for removing B and P impurities in chlorosilane is urgently needed.

[0003] The solid adsorption method can overcome the difficulty that the rectification method is difficult to remove strong polar impurities. The adsorption method is an operation method for adsorbing and separating impurities in chlorosilane by using a solid adsorbent. The general requirements for the adsorbent are: 1) having a large surface area; and 2) having a large surface activity. There are some related reports on the use of solid adsorbents to adsorb and separate impurities in chlorosilane, but most of the adsorbents used are molecular sieves, silicon-aluminum oxides, artificial zeolites, silica gels, activated carbons, resins, or molecular sieves, silicon-aluminum oxides, artificial zeolites, silica gels, activated carbons, resins loaded with complexing agents, or B and P are removed by using different adsorbents respectively. The adsorption effect is poor, and B and P impurities in chlorosilane cannot be simultaneously and efficiently removed.

[0004] For example, Chinese patent document CN105800617A discloses a method and equipment for removing boron and phosphorus impurities in chlorosilane by chemical adsorption and reaction rectification. The bag is filled with molecular sieves, silicon-aluminum oxides, artificial zeolites, silica gels, activated carbons, resins or their combinations loaded with complexing agents.

[0005] For example, Chinese patent document CN116062758A discloses a boron and phosphorus impurity adsorption device. The adsorption device comprises a cylinder, a baffle arranged in the cylinder, a first filling cavity and a second filling cavity arranged in the cylinder and located at two ends of the baffle respectively. The first filling cavity is filled with a first adsorbent for removing boron impurities, and the second filling cavity is filled with a second adsorbent for removing phosphorus impurities. The first adsorbent comprises one or more of activated carbon, silicate, oxide, molecular sieve, boron selective adsorption functional group loaded, modified silica gel and activated carbon. The second adsorbent comprises silica gel and active zeolite.

[0006] The patent document has poor adsorption effect and cannot simultaneously and efficiently remove B and P impurities in chlorosilane.

[0007] Metal-organic frameworks (MOFs) are organic-inorganic hybrid materials with intramolecular pores, which are formed by self-assembly of organic ligands and metal ions or clusters through coordination bonds. Due to the unique and excellent surface properties of MOFs, such as high specific surface area and adjustable porosity, MOFs have been widely explored in the field of adsorption and separation. Among them, Zeolitic Imidazolate Framework-8 (ZIF-8) is a kind of metal-organic framework material with large specific surface area, good thermal stability and chemical stability. It has a topological structure similar to sodium zeolite and combines the advantages of metal-organic framework materials and natural zeolite.

[0008] It is necessary to develop a new method for efficiently removing B and P impurities in chlorosilane. SUMMARY

[0009] In view of the deficiencies of the prior art, the present application provides a method for simultaneously and efficiently removing B and P impurities in chlorosilane based on Cu@ZIF-8 adsorbent. The removal rate of B is as high as 80%, and the removal rate of P is as high as 93%, effectively solving the problem of difficult removal of B and P impurities in chlorosilane.

[0010] The present application is realized by the following technical solutions:

[0011] The method for simultaneously and efficiently removing B and P impurities in chlorosilane based on Cu@ZIF-8 adsorbent comprises the following steps:

[0012] The Cu@ZIF-8 adsorbent is added to the liquid chlorosilane, and after sealing, it is oscillated in an ice water bath for 1-4 hours to simultaneously and efficiently remove B and P impurities in chlorosilane;

[0013] The Cu@ZIF-8 adsorbent is prepared by the following method:

[0014] (1) Dissolve zinc nitrate hydrate and dimethyl imidazole in methanol, stir at room temperature, centrifuge, wash and vacuum dry the mixed solution after the reaction is completed to obtain solid powder A;

[0015] (2) Calcine the solid powder A under inert atmosphere to obtain ZIF-8;

[0016] (3) Disperse the ZIF-8 powder in an organic solvent to obtain solution A;

[0017] (4) dissolving copper nitrate hydrate into an organic solvent to obtain solution B;

[0018] (5) cooling solution A and solution B in an ice water bath respectively, titrating solution B into solution A under stirring, reacting for 1-5 hours, centrifuging, washing and vacuum drying the mixed solution to obtain solid powder B;

[0019] (6) calcining the solid powder B under an inert atmosphere to obtain Cu@ZIF-8 adsorbent.

[0020] According to the application, preferably, the mass-volume ratio of the dosage of Cu@ZIF-8 adsorbent to liquid chlorosilane is (0.5-3):(10-30), unit, g / mL.

[0021] According to the application, preferably, the oscillation time in the ice water bath is 2 hours.

[0022] According to the application, preferably, in step (1), the molar ratio of zinc nitrate hydrate to dimethyl imidazole is 1:(7-9).

[0023] According to the application, preferably, in step (1), the mass ratio of dimethyl imidazole to methanol is (0.1-0.5):1.

[0024] According to the application, preferably, in step (1), the reaction time is 3-8 hours.

[0025] According to the application, preferably, in step (2), the calcination temperature is 300-500℃.

[0026] According to the application, preferably, in step (2), the calcination time is 2-4 hours.

[0027] According to the application, preferably, in step (3), the mass-volume ratio of ZIF-8 powder to organic solvent is (5-20):(5-30), unit, g / mL.

[0028] According to the application, preferably, in step (4), the mass-volume ratio of copper nitrate hydrate to organic solvent is (5-20):(0.5-1), unit, mg / mL.

[0029] According to the application, preferably, in steps (3) and (4), the organic solvent is methanol or ethanol.

[0030] According to the application, preferably, in step (5), the amount of solution B and solution A is such that the mass ratio of copper nitrate hydrate to ZIF-8 is (0.001-0.01):1.

[0031] According to the application, preferably, in step (5), the cooling time in the ice water bath is 10-20 minutes.

[0032] According to the application, preferably, in step (1)(5), the vacuum drying temperature is 30-50 DEG C, and the vacuum drying time is 8-10 hours.

[0033] According to the application, preferably, in step (2)(6), the inert atmosphere is nitrogen or argon.

[0034] According to the application, preferably, in step (6), the calcination temperature is 300-500 DEG C, and the calcination time is 2-4 hours.

[0035] The technical features and advantages of the application are as follows:

[0036] 1. The method for simultaneously and efficiently removing B and P impurities in chlorosilane is based on Cu@ZIF-8 adsorbent, the ZIF-8 and Cu in the Cu@ZIF-8 adsorbent are synergistic, which greatly improves the removal rate of B and P impurities, one adsorbent can simultaneously and efficiently remove B and P impurities, effectively solves the problem that B and P impurities are difficult to remove in the chlorosilane system, and exhibits excellent adsorption performance in the removal of B and P impurities in the chlorosilane system, the removal rate of B is as high as 80%, and the removal rate of P is as high as 93%.

[0037] 2. The Cu@ZIF-8 adsorbent of the application is calcined under an inert atmosphere to obtain ZIF-8, the ZIF-8 is mixed with a copper source, dried and calcined to obtain, and the calcination under the inert atmosphere makes the Cu uniformly and firmly loaded on the ZIF-8, so that the Cu@ZIF-8 adsorbent with excellent adsorption performance is obtained, and when the loading amount of Cu is 5 ‰, the removal rate of B and P impurities in the chlorosilane system reaches the optimum.

[0038] 3. The method of the application can simultaneously and efficiently remove B and P impurities in the chlorosilane system by using one adsorbent.

[0039] 4. The method of the application is easy to separate the adsorbent, and the adsorbent can be reused by desorption under nitrogen, which saves cost and has potential application value in the industrial field. DETAILED DESCRIPTION

[0040] The application will be further described below in combination with specific examples, but is not limited thereto.

[0041] In the following examples, the method described in the examples is a conventional method unless otherwise specified, and the materials, reagents and the like can be obtained from commercial channels unless otherwise specified.

[0042] The liquid chlorosilane in the examples is liquid chlorosilane containing B and P impurities that does not meet the requirements after multi-stage rectification.

[0043] Example 1

[0044] Synthesis of adsorbent 1 ‰-Cu@ZIF-8:

[0045] (1) Take 29.75 g of zinc nitrate hydrate and 65.68 g of dimethylimidazole, dissolve them in 250 ml of methanol, stir the reaction at room temperature for 5 hours, after the reaction is completed, centrifuge, wash the mixed solution, and dry it at 50°C under vacuum for 8 hours to obtain solid powder A;

[0046] (2) Calcine the solid powder A at 300°C for 2 hours under nitrogen to obtain sample ZIF-8;

[0047] (3) Take 10 g of ZIF-8 powder and disperse it in 10 ml of methanol to obtain solution A;

[0048] (4) Take 10 mg of copper nitrate hydrate and dissolve it in 1 ml of methanol to obtain solution B;

[0049] (5) Cool solutions A and B in an ice water bath for 10 minutes, titrate solution B into solution A under stirring, react for 2 hours, centrifuge, wash, and vacuum dry the mixed solution to obtain solid powder B;

[0050] (6) After calcining the solid powder B under a nitrogen atmosphere for 2 hours, obtain adsorbent 1‰-Cu@ZIF-8.

[0051] The synthesized adsorbent 1‰-Cu@ZIF-8 is used for adsorption of B and P impurities in chlorosilane, in the following manner:

[0052] Before adsorption, dry the adsorbent 1‰-Cu@ZIF-8 at 150°C for 4 hours.

[0053] Take 1 g of adsorbent 1‰-Cu@ZIF-8 and add it to 20 ml of liquid chlorosilane, seal all the solutions containing the adsorbent in a 100 mL round-bottom flask, and then shake in a constant-temperature operating shaking water bath for 2 hours. After adsorption equilibrium, freeze centrifuge the mixed solution, and take the supernatant for ICP-MS detection. The results show that the removal rate of the adsorbent for B is 75%, and the removal rate for P is 85%.

[0054] Dry the separated solid material under nitrogen blowing, calcine it at 200°C for 1 hour under an argon atmosphere for thermal desorption, continue to adsorb B and P impurities in chlorosilane from the treated sample according to the above method, and detect B and P in chlorosilane after adsorption is completed. The results show that the removal rate of the adsorbent for B is 73%, and the removal rate for P is 81%. After desorption and reuse under nitrogen, the removal rates of the adsorbent for B and P impurities remain basically unchanged, indicating that the adsorbent of the application has good reuse performance.

[0055] Example 2

[0056] Synthesis of adsorbent 2‰-Cu@ZIF-8:

[0057] (1) Take 29.75 g of zinc nitrate hydrate and 65.68 g of dimethylimidazole, dissolve them in 250 ml of methanol, stir the reaction at room temperature for 5 hours, after the reaction is completed, centrifuge, wash, and vacuum dry the mixed solution at 50°C for 8 hours to obtain solid powder A;

[0058] (2) Calcine the solid powder A under nitrogen at 350°C for 2 hours to obtain sample ZIF-8;

[0059] (3) Take 10 g of ZIF-8 powder and disperse it in 10 ml of methanol to obtain solution A;

[0060] (4) Take 20 mg of copper nitrate hydrate and dissolve it in 1 ml of methanol to obtain solution B;

[0061] (5) Cool solutions A and B in an ice water bath for 10 minutes, titrate solution B into solution A under stirring, react for 2 hours, centrifuge, wash, and vacuum dry the mixed solution to obtain solid powder B;

[0062] (6) After calcining the solid powder B under a nitrogen atmosphere for 2 hours, obtain adsorbent 2 ‰-Cu@ZIF-8.

[0063] The synthesized adsorbent 2 ‰-Cu@ZIF-8 is used for adsorption of B and P impurities in chlorosilane, in the following manner:

[0064] Before adsorption, the adsorbent is dried at 150°C for 4 hours.

[0065] Take 1 g of adsorbent 2 ‰-Cu@ZIF-8 and add it to 20 ml of liquid chlorosilane, seal all the solutions containing the adsorbent in a 100 mL round-bottom flask, and then shake in a constant-temperature operating shaking water bath for 2 hours. After adsorption equilibrium, freeze centrifuge the mixed solution, and take the supernatant for ICP-MS detection. The results show that the removal rate of the adsorbent for B is 76%, and the removal rate for P is 88%.

[0066] The separated solid material is dried under nitrogen blowing, and after drying, is calcined at 200°C under an argon atmosphere for 1 hour for thermal desorption. The treated sample continues to be used for adsorption of B and P impurities in chlorosilane according to the above method, and after adsorption is completed, B and P in the chlorosilane are detected. The results show that the removal rate of the adsorbent for B is 74%, and the removal rate for P is 83%. After repeated use under nitrogen desorption, the removal rates of the adsorbent for B and P impurities remain basically unchanged, indicating that the adsorbent of the application has good repeated use performance.

[0067] Example 3

[0068] Synthesis of adsorbent 5 ‰-Cu@ZIF-8:

[0069] (1) Take 29.75 g of zinc nitrate hydrate and 65.68 g of dimethylimidazole, dissolve them in 250 ml of methanol, stir the reaction at room temperature for 5 hours, after the reaction is completed, centrifuge, wash, and vacuum dry the mixed solution at 50°C for 8 hours to obtain solid powder A;

[0070] (2) After calcining the solid powder A at 400°C for 2 hours under nitrogen, sample ZIF-8 is obtained;

[0071] (3) Take 10 g of ZIF-8 powder and disperse it in 10 ml of methanol to obtain solution A;

[0072] (4) Take 50 mg of copper nitrate hydrate and dissolve it in 1 ml of methanol to obtain solution B;

[0073] (5) Cool solutions A and B in an ice water bath for 10 minutes, titrate solution B into solution A under stirring, react for 2 hours, centrifuge, wash, and vacuum dry the mixed solution to obtain solid powder B;

[0074] (6) After calcining the solid powder B for 2 hours under a nitrogen atmosphere, adsorbent 5 ‰-Cu@ZIF-8 is obtained.

[0075] The synthesized adsorbent 5 ‰-Cu@ZIF-8 is used for adsorption of B and P impurities in chlorosilane, in the following manner:

[0076] Before adsorption, the adsorbent is dried at 150°C for 4 hours.

[0077] Take 1 g of adsorbent 5 ‰-Cu@ZIF-8 and add it to 20 ml of liquid chlorosilane, seal all the solutions containing the adsorbent in a 100 mL round-bottom flask, and then shake in a constant-temperature operating shaking water bath for 2 hours. After adsorption equilibrium, freeze centrifuge the mixed solution, and take the supernatant for ICP-MS detection. The results show that the removal rate of the adsorbent for B is 80%, and the removal rate for P is 93%.

[0078] The separated solid material is dried under nitrogen blowing, and after drying, is calcined at 200°C for 1 hour under an argon atmosphere for thermal desorption. The treated sample continues to be used for adsorption of B and P impurities in chlorosilane according to the above method, and after adsorption is completed, B and P in the chlorosilane are detected. The results show that the removal rate of the adsorbent for B is 77%, and the removal rate for P is 90%. After repeated use under nitrogen desorption, the removal rates of the adsorbent for B and P impurities remain basically unchanged, indicating that the adsorbent of the application has good repeated use performance.

[0079] Example 4

[0080] Synthesis of adsorbent 1% -Cu@ZIF-8:

[0081] (1) Take 29.75 g of zinc nitrate hydrate and 65.68 g of dimethylimidazole, dissolve them in 250 ml of methanol, stir the reaction at room temperature for 5 hours, after the reaction is completed, centrifuge, wash, and vacuum dry the mixed solution at 50°C for 8 hours to obtain solid powder A;

[0082] (2) After calcining the solid powder A at 400°C for 2 hours under nitrogen, sample ZIF-8 is obtained;

[0083] (3) Take 10 g of ZIF-8 powder and disperse it in 10 ml of methanol to obtain solution A;

[0084] (4) Take 0.1 g of copper nitrate hydrate and dissolve it in 1 ml of methanol to obtain solution B;

[0085] (5) Cool solutions A and B in an ice water bath for 20 minutes, titrate solution B into solution A under stirring, react for 2 hours, centrifuge, wash, and vacuum dry the mixed solution to obtain solid powder B;

[0086] (6) After calcining the solid powder B for 2 hours under a nitrogen atmosphere, adsorbent 1%-Cu@ZIF-8 is obtained.

[0087] The synthesized adsorbent 1%-Cu@ZIF-8 is used for adsorption of B and P impurities in chlorosilane, in the following manner:

[0088] Before adsorption, the adsorbent is dried at 150°C for 4 hours.

[0089] Take 1 g of adsorbent 1%-Cu@ZIF-8 and add it to 20 ml of liquid chlorosilane, seal all the solutions containing the adsorbent in a 100 mL round-bottom flask, and then shake in a constant-temperature operating shaking water bath for 2 hours. After adsorption equilibrium, freeze centrifuge the mixed solution, and take the supernatant for ICP-MS detection. The results show that the removal rate of the adsorbent for B is 80%, and the removal rate for P is 86%.

[0090] The separated solid material is dried under nitrogen blowing, and after drying, is calcined at 200°C for 1 hour under an argon atmosphere for thermal desorption. The treated sample continues to be used for adsorption of B and P impurities in chlorosilane according to the above method, and after adsorption is completed, B and P in the chlorosilane are detected. The results show that the removal rate of the adsorbent for B is 76%, and the removal rate for P is 82%. After repeated use under nitrogen desorption, the removal rates of the adsorbent for B and P impurities remain basically unchanged, indicating that the adsorbent of the application has good repeated use performance.

[0091] Comparative Example 1

[0092] Synthesis of adsorbent Air-5‰-Cu@ZIF-8:

[0093] (1) Take 29.75 g of zinc nitrate hydrate and 65.68 g of dimethylimidazole, dissolve them into 250 ml of methanol, stir the reaction at room temperature for 5 hours, after the reaction is completed, centrifuge, wash, and vacuum dry the mixed solution at 50°C for 8 hours to obtain solid powder A;

[0094] (2) Calcine the above solid powder A at 400°C for 2 hours under air to obtain sample ZIF-8;

[0095] (3) Take 10 g of ZIF-8 powder, disperse it into 10 ml of methanol to obtain solution A;

[0096] (4) Take 50 mg of copper nitrate hydrate, dissolve it into 1 ml of methanol to obtain solution B;

[0097] (5) Cool solutions A and B in an ice water bath for 20 minutes, under stirring, titrate solution B into solution A, react for 2 hours, centrifuge, wash, and vacuum dry the mixed solution to obtain solid powder B;

[0098] (6) Calcine the solid powder B under nitrogen atmosphere for 2 hours to obtain adsorbent Air-5‰-Cu@ZIF-8.

[0099] Use the above-synthesized adsorbent Air-5‰-Cu@ZIF-8 for adsorption of B and P impurities in chlorosilane, in the following manner:

[0100] Before adsorption, dry the adsorbent at 150°C for 4 hours.

[0101] Take 1 g of adsorbent, add it into 20 ml of liquid chlorosilane, seal all the solutions containing the adsorbent in a 100 ml round-bottom flask, and then shake in an ice water bath under constant temperature operation for 2 hours. After adsorption equilibrium, freeze centrifuge the mixed solution, and take the supernatant for ICP-MS detection. The results show that the removal rate of the adsorbent for B is 58%, and the removal rate for P is 65%.

[0102] The comparative example is calcined under air atmosphere to obtain ZIF-8, which is mixed with a copper source, dried, and calcined to obtain Air-5‰-Cu@ZIF-8. The removal rates of B and P impurities are much smaller than those of the present application, which is attributed to the small pore size of the ZIF-8 calcined under air atmosphere.

[0103] Comparative Example 2

[0104] Synthesis of adsorbent Air-1‰-Cu@ZIF-8:

[0105] (1) 29.75 g of zinc nitrate hydrate and 65.68 g of dimethylimidazole were weighed out and dissolved in 250 ml of methanol, and the reaction was stirred at room temperature for 5 hours. After the reaction was completed, the mixed solution was centrifuged, washed, and dried at 50°C under vacuum for 8 hours to obtain solid powder A;

[0106] (2) The solid powder A was calcined at 400°C for a certain time under air to obtain sample ZIF-8;

[0107] (3) 10 g of ZIF-8 powder was weighed out and dispersed in 10 ml of methanol to obtain solution A;

[0108] (4) 10 mg of copper nitrate hydrate was weighed out and dissolved in 1 ml of methanol to obtain solution B;

[0109] (5) Solution A and B were cooled in an ice water bath for 10 minutes, and solution B was titrated into solution A under stirring, and the reaction was carried out for 2 hours. The mixed solution was centrifuged, washed, and dried under vacuum to obtain solid powder B;

[0110] (6) The solid powder B was calcined under a nitrogen atmosphere for 2 hours to obtain adsorbent Air-1‰-Cu@ZIF-8.

[0111] The adsorbent Air-1‰-Cu@ZIF-8 synthesized above was used for the adsorption of B and P impurities in chlorosilane:

[0112] Before adsorption, the adsorbent was dried at 150°C for 4 hours.

[0113] 1 g of the adsorbent was weighed out and added to 20 ml of liquid chlorosilane, and all the solutions containing the adsorbent were sealed in a 100 mL round-bottom flask, and then shaken in a constant-temperature operating shaking water bath for 2 hours. After the adsorption equilibrium, the mixed solution was frozen and centrifuged, and the supernatant was detected by ICP-MS. The results showed that the removal rate of the adsorbent for B was 55%, and the removal rate for P was 59%.

[0114] The comparative example was calcined under air to obtain ZIF-8, which was mixed with a copper source, dried, and calcined to obtain adsorbent Air-1‰-Cu@ZIF-8. The removal rates of B and P impurities were much smaller than those of the present application, which was attributed to the small pore size of ZIF-8 calcined under air and the small amount of Cu, which reduced the complexation of P, and weakened the adsorption of P.

Claims

1. A method for simultaneously and efficiently removing B and P impurities in chlorosilane based on Cu@ZIF-8 adsorbent, the method comprising the following steps: adding Cu@ZIF-8 adsorbent into liquid chlorosilane, sealing, and oscillating in an ice water bath for 2 hours, the mass / volume ratio of the addition amount of Cu@ZIF-8 adsorbent to liquid chlorosilane being (0.5-3) : (10-30), units, g / mL, to simultaneously and efficiently remove B and P impurities in chlorosilane; the Cu@ZIF-8 adsorbent is prepared by the following method: (1) dissolving zinc nitrate hydrate and dimethyl imidazole in methanol, stirring at room temperature, centrifuging, washing, and vacuum drying the mixed solution after the reaction is completed to obtain solid powder A; (2) calcining the solid powder A under an inert atmosphere to obtain ZIF-8, the calcination temperature being 300-500 DEG C, the calcination time being 2-4 hours, and the inert atmosphere being nitrogen or argon; (3) dispersing the ZIF-8 powder into an organic solvent to obtain solution A; (4) dissolving copper nitrate hydrate in the organic solvent to obtain solution B; (5) cooling solution A and solution B in an ice water bath, titrating solution B into solution A under stirring, reacting for 1-5 hours, and centrifuging, washing, and vacuum drying the mixed solution to obtain solid powder B; the amount of solution B and solution A is such that the mass ratio of copper nitrate hydrate to ZIF-8 is (0.001-0.01) : 1, and the cooling time in the ice water bath is 10-20 minutes; (6) calcining the solid powder B under an inert atmosphere to obtain Cu@ZIF-8 adsorbent, the inert atmosphere being nitrogen or argon, the calcination temperature being 300-500 DEG C, and the calcination time being 2-4 hours.

2. The method of claim 1, wherein, In step (1), the molar ratio of zinc nitrate hydrate to dimethyl imidazole is 1 : (7-9), the mass ratio of dimethyl imidazole to methanol is (0.1-0.5) : 1, and the reaction time is 3-8 hours.

3. The method of claim 1, wherein, In step (3), the mass / volume ratio of ZIF-8 powder to organic solvent is (5-20) : (5-30), units, g / mL.

4. The method of claim 1, wherein, In step (4), the mass / volume ratio of copper nitrate hydrate to organic solvent is (5-20) : (0.5-1), units, mg / mL.

5. The method of claim 1, wherein, In steps (3) and (4), the organic solvent is methanol or ethanol.

6. The method of claim 1, wherein, In steps (1) and (5), the vacuum drying temperature is 30-50 DEG C, and the vacuum drying time is 8-10 hours.