Air-stable metal organic framework as well as preparation method and application thereof

Abstract

The invention provides an air-stable metal organic framework as well as a preparation method and application thereof. The metal organic framework with stable air disclosed by the invention is CuI2 (BBTA). According to the novel MOFs material CuI2 (BBTA), a part of Cu (I) is connected with four N atoms, unsaturated points around the Cu (I) are reduced, and the air stability of the material is improved. The material disclosed by the invention is stable in air, and Cu (I) can be conveniently kept from being oxidized in a preparation process, a transfer process and a charging process, so that a hydrogen isotope gas separation effect is better exerted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic frameworks, in particular to an air-stable metal-organic framework and a preparation method and application thereof. BACKGROUND

[0002] With the development of social economy, the consumption of natural resources is increasing day by day. As a new type of energy, the most important advantage of nuclear energy is that it releases a huge amount of energy, which can support future energy demand. According to the Energy Technology Outlook (IEA) in 2023, by 2050, nuclear energy will account for 12% of the total global primary energy supply. Nuclear energy is divided into fission energy and fusion energy. At present, only fission reactors have been commercialized, while the research and development of fusion reactors is ongoing. Compared with fission energy, fusion energy has the outstanding advantages of abundant fuel, low fuel price, small environmental pollution, safe and reliable operation, and large energy release. ITER and the next generation of DEMO fusion reactors require a large amount of tritium during testing and startup, and thousands of kilograms of tritium are burned every year to maintain operation. The abundance of tritium in nature is only 10 -18 orders of magnitude, so the amount of tritium is one of the key issues for the development of future fusion energy.

[0003] The fusion combustion process (D + T → 4 He + n + 17.59 MeV) has strict requirements for the content of tritium, and the combustion efficiency of tritium is less than 3%. A large amount of unburned tritium is discharged with the exhaust gas, making it difficult for fusion to be self-sustaining. This not only causes a great waste of raw materials, but also has an impact on the environment. Therefore, it is necessary to develop an efficient deuterium-tritium separation technology to separate the unburned tritium and re-inject it into the combustion chamber to participate in the fusion reaction.

[0004] Hydrogen isotope gases often require a large amount of energy to separate due to their small mass difference and similar chemical properties. Current hydrogen isotope gas separation technologies mainly include palladium membrane permeation, low-temperature rectification, thermal diffusion, chromatography, thermal cycle adsorption, and quantum sieve separation. The first four methods have problems such as high energy consumption and low separation efficiency, which limits their application. Thermal cycle adsorption (TCAP) is an improved chromatography method that is simple to operate, low in energy consumption, and high in separation efficiency. It consists of a separation column and a reflux column, and the separation column is filled with materials such as palladium-loaded alumina that have hydrogen isotope effects. The reflux column mainly serves as a temporary storage, but the gas will mix again in the reflux column, reducing the separation efficiency. By adding appropriate packing materials to the reflux column, the separation efficiency of thermal cycle adsorption can be further improved. Quantum sieve separation mainly uses the quantum effect and chemical affinity effect of microporous materials to separate hydrogen isotopes, and the microporous materials are a good reflux column packing material.

[0005] Metal organic frameworks (MOFs) have high specific surface area, adjustable pore structure, structural diversity, high concentration of open metal sites, and strong adsorption centers that can be introduced into the framework. By adjusting the pore size and open metal sites, MOFs can exhibit anti-hydrogen isotope effect, making them important materials for quantum sieving method. More importantly, due to the anti-hydrogen isotope effect of certain metal organic frameworks, they can also rely on the separation equipment of thermal swing adsorption method, as the filling material of the reflux column, and also can play a higher role in hydrogen isotope separation. Therefore, MOFs materials with active metal sites are a kind of hydrogen isotope separation material with wide research prospects.

[0006] However, there are some problems in MOFs materials that need to be solved. For example, the material has organic groups, and the stability is not enough when separating radioactive tritium; MOFs materials have quantum sieving effect only at low temperature, and the energy consumption of cooling is large; the metal active center is easily oxidized in air and loses activity. In recent years, researchers have confirmed that monovalent copper (Cu(I)) is suitable as a metal active site of metal organic framework material for hydrogen isotope separation. For example, in “Highly Effective H2 / D2Separation within the Stable Cu(I)Cu(II)-BTC: The Effect of Cu(I) Structure on Quantum Sieving”, researchers use Cu(I)(II)-BTC to separate hydrogen isotopes, but this material has the common problem of Cu(I) instability.

[0007] Therefore, it is necessary to develop a Cu(I) stable MOFs material to improve its air stability. SUMMARY

[0008] The present application provides an air-stable metal organic framework and its preparation method and application to solve the problem of Cu(I) instability in the prior art.

[0009] The technical method of the present application is as follows: In a first aspect, the present application provides an air-stable metal organic framework, which is Cu I 2(BBTA).

[0010] In a second aspect, the present application provides a preparation method of an air-stable metal organic framework, which comprises: hydrothermal reaction of copper salt, zinc salt, organic ligand and solvent, washing, drying to obtain metal organic framework, here, the molar ratio of copper salt, zinc salt, organic ligand and solvent is 2-15:1-10:1:500-10000; or the copper salt, the organic ligand and the solvent are subjected to hydrothermal reaction, washing and drying to obtain the metal organic framework, and the molar ratio of the copper salt, the organic ligand and the solvent is 2-15:1:500-10000.

[0011] The copper salt includes one or more of CuCl2 xH2O, Cu(NO3)2 xH2O and CuSO4 xH2O, wherein x=0-10; the zinc salt includes one or more of ZnCl2 xH2O, Zn(NO3)2 xH2O and ZnSO4 xH2O, wherein x=0-10; the organic ligand is 1,5-dihydrobenzo[1,2-d:4,5-d']bis([1,2,3]triazole) (H2BBTA); and the solvent includes N,N-dimethylformamide (DMF) and / or N,N-dimethylacetamide (DMA).

[0012] Specifically, the preparation method of the present application has three schemes.

[0013] Scheme 1: the steps of hydrothermal reaction, washing and drying of the copper salt, the zinc salt, the organic ligand and the solvent include: Step 1: the copper salt, the zinc salt, the organic ligand and the solvent are reacted at 100-150°C for 48-168 hours to obtain a reaction product, Step 2: the reaction product is centrifuged at a speed of 2000-6000 r / min for 4-8 minutes, the supernatant is removed, and then the product is washed with a detergent, centrifuged and the supernatant is removed to obtain a product; Step 3: the product is vacuum dried in a vacuum drying oven at 60-90°C for 2-6 hours to obtain Cu I 2(BBTA).

[0014] Scheme 2: the steps of hydrothermal reaction, washing and drying of the copper salt, the zinc salt, the organic ligand and the solvent include: Step 1: the copper salt and the organic ligand are added to the solvent, reacted at 100-150°C for 24-72 hours, and then the zinc salt is added, and the reaction is continued at 100-150°C for 24-72 hours to obtain a reaction product; Step 2: the reaction product is centrifuged at a speed of 2000-6000 r / min for 4-8 minutes, the supernatant is removed, and then the product is washed with a detergent, centrifuged and the supernatant is removed to obtain a product; Step 3: the product is vacuum dried in a vacuum drying oven at 60-90°C for 2-6 hours to obtain Cu I 2(BBTA).

[0015] Scheme 3: the steps of hydrothermal reaction, washing and drying of the copper salt, the organic ligand and the solvent include: Step 1: reacting copper salt, organic ligand and solvent at 100-150℃ for 20-23 days to obtain a reaction product; Step 2: centrifuging the reaction product at a speed of 2000-6000 r / min for 4-8 minutes to remove supernatant, and then washing, centrifuging and removing supernatant to obtain a product; Step 3: vacuum drying the product in a vacuum drying oven at 60-90℃ for 2-6 hours to obtain Cu I 2(BBTA).

[0016] The detergent in schemes one to three includes one or more of N,N-dimethylacetamide, methanol and dichloromethane.

[0017] In a third aspect, the application provides a use of a metal organic framework for separating hydrogen isotopes. Here, the metal organic framework is used as a filling material of a reflux column of a thermal swing adsorption device; the hydrogen isotopes are any two of H2, HD, D2, HT, DT and T2; the separation pressure is 10-500000 Pa; the temperature is -243--196℃; the separation cycle is 2-50 times; and the separation time in a single cycle is 1-1000 minutes.

[0018] The application has the following advantages: The application designs a new MOFs material (Cu I 2(BBTA) in which a part of Cu(I) is connected to four N atoms, reducing the unsaturated points around Cu(I) and improving the air stability of the material. The material is stable in air, which makes it easier to keep Cu(I) from being oxidized during the preparation process, transfer process and loading process, thus better playing the role of separating hydrogen isotope gas. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The XRD spectrum of Cu I 2(BBTA) in Example 1; Figure 2 The graph of the change of D2 content in 5D2 / 95H2 mixed gas with the number of cycles when the separation pressure is 10000 Pa, the separation time is 10 minutes and the separation temperature is -223℃. DETAILED DESCRIPTION

[0020] The technical solutions of the application will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0021] The present application is based on the following concept: in the existing research on the separation of hydrogen isotope gas using MOFs containing metal active sites, the separation effect of Cu(I) sites is the best. The Cu(I) metal site has the largest difference in adsorption enthalpy of hydrogen isotope gas, and is therefore a very suitable metal site for separation. However, the current Cu(I)-containing MOF materials generally have the disadvantage that Cu(I) is unstable and is easily oxidized to Cu(II), and Cu(II) has a poor separation effect on hydrogen isotope gas.

[0022] Based on this, the present application provides an air-stable metal organic framework, which is Cu I 2(BBTA), which connects a part of Cu(I) to four N atoms, reduces the unsaturated points around Cu(I), and improves the air stability of the material. The material of the present application is stable in air, which facilitates the maintenance of Cu(I) from being oxidized during the preparation process, transfer process and charging process, so as to better play the role of hydrogen isotope gas separation.

[0023] In the second aspect, the present application provides a preparation method of an air-stable metal organic framework, which comprises: subjecting a copper salt, a zinc salt, an organic ligand and a solvent to a hydrothermal reaction, washing and drying to obtain a metal organic framework, wherein the molar ratio of the copper salt, the zinc salt, the organic ligand and the solvent is 2-15:1-10:1:500-10000. Or subjecting a copper salt, an organic ligand and a solvent to a hydrothermal reaction, washing and drying to obtain a metal organic framework, wherein the molar ratio of the copper salt, the organic ligand and the solvent is 2-15:1:500-10000.

[0024] For example, the molar ratio of the copper salt, the zinc salt, the organic ligand and the solvent can be 5:5:1:70000, 10:8:1:900. The molar ratio of the copper salt, the organic ligand and the solvent can be 6:1:700, 10:1:900.

[0025] In the present application, the copper salt includes one or more of CuCl2.xH2O, Cu(NO3)2.xH2O and CuSO4.xH2O, wherein x=0-10. For example, x can be 0, 1, 4, 7 or 9.

[0026] In the present application, the zinc salt includes one or more of ZnCl2.xH2O, Zn(NO3)2.xH2O and ZnSO4.xH2O, wherein x=0-10. For example, x can be 0, 1, 4, 7 or 9.

[0027] In the present application, the organic ligand is 1,5-dihydrobenzo[1,2-d:4,5-d']bis([1,2,3]triazole). The solvent includes N,N-dimethylformamide and / or N,N-dimethylacetamide.

[0028] Specifically, the application can be prepared by scheme one, scheme two and scheme three to prepare Cu I 2(BBTA).

[0029] The preparation method of scheme one comprises the following steps: Step 1: the copper salt, zinc salt, organic ligand and solvent are reacted at 100-150 DEG C for 48-168 hours to obtain a reaction product. For example, the reaction temperature can be 120 DEG C, 140 DEG C. The reaction time can be 72 hours, 140 hours.

[0030] Step 2: the reaction product is centrifuged at a speed of 2000-6000 r / min for 4-8 minutes, the supernatant is removed, and then the product is obtained by washing with a detergent, centrifuging and removing the supernatant. For example, the speed is 3000 r / min, 4000 r / min, 5000 r / min. The detergent comprises one or more of N,N-dimethylacetamide, methanol and dichloromethane. Specifically, the washing can be carried out by using N,N-dimethylacetamide first, then N,N-dimethylacetamide, and finally dichloromethane.

[0031] Step 3: the product is vacuum dried in a vacuum drying box at 60-90 DEG C for 2-6 hours to obtain Cu I 2(BBTA). For example, the temperature of vacuum drying can be 80 DEG C, and the time of vacuum drying can be 4 hours.

[0032] The preparation method of scheme two comprises the following steps: Step 1: the copper salt and the organic ligand are added to the solvent, and reacted at 100-150 DEG C for 24-72 hours, and then the zinc salt is added, and the reaction is continued at 100-150 DEG C for 24-72 hours to obtain a reaction product. For example, the reaction temperature can be 120 DEG C, 140 DEG C. The reaction time can be 36 hours, 48 hours.

[0033] Step 2: the reaction product is centrifuged at a speed of 2000-6000 r / min for 4-8 minutes, the supernatant is removed, and then the product is obtained by washing with a detergent, centrifuging and removing the supernatant. For example, the speed is 3000 r / min, 4000 r / min, 5000 r / min. The detergent comprises one or more of N,N-dimethylacetamide, methanol and dichloromethane. Specifically, the washing can be carried out by using N,N-dimethylacetamide first, then N,N-dimethylacetamide, and finally dichloromethane.

[0034] Step 3: the product is vacuum dried in a vacuum drying box at 60-90 DEG C for 2-6 hours to obtain Cu I 2(BBTA). For example, the temperature of vacuum drying can be 80 DEG C, and the time of vacuum drying can be 4 hours.

[0035] The preparation method of scheme three comprises the following steps: Step 1: reacting a copper salt, an organic ligand and a solvent at 100-150℃ for 20-23 days to obtain a reaction product. For example, the reaction temperature can be 120℃, 140℃. The reaction time can be 21 days, 22 days.

[0036] Step 2: centrifuging the reaction product at a speed of 2000-6000 r / min for 4-8 minutes to remove the supernatant, and then washing, centrifuging and removing the supernatant to obtain a product. For example, the speed can be 3000 r / min, 4000 r / min, 5000 r / min. The washing agent comprises one or more of N,N-dimethylacetamide, methanol and dichloromethane. Specifically, the washing can be performed in the following order: N,N-dimethylacetamide, N,N-dimethylacetamide and dichloromethane.

[0037] Step 3: vacuum drying the product in a vacuum drying box at 60-90℃ for 2-6 hours to obtain Cu I 2(BBTA). For example, the temperature of vacuum drying can be 80℃, and the time of vacuum drying can be 4 hours.

[0038] In scheme one and scheme two of the present application, a zinc salt is used. As a catalyst, the use of a zinc salt can reduce the reaction time. When the zinc salt participates in the reaction, an intermediate product is generated. The intermediate products in the two cases of adding the zinc salt at the same time and separately are different, but the results are the same, which belong to two reaction pathways.

[0039] In a third aspect, the present application provides an application of a metal organic framework in separating hydrogen isotope gas. Here, the metal organic framework is used as a filling material of a reflux column of a thermal swing adsorption device.

[0040] In the present application, Cu I 2(BBTA) is used to separate hydrogen isotopes. The steps can comprise: Step 1: filling 1-1000 g of a metal organic framework (Cu I 2(BBTA) into a reflux column of a thermal swing adsorption (TCAP) device; Step 2: in the reflux column, first increasing the temperature to 60-120℃ at a heating rate of 2-5℃ / min, keeping vacuum for 0.5-1 hour, and the pressure in the column is <1 Pa, and then increasing the temperature to 160-200℃ at a heating rate of 2-5℃ / min, vacuum activating for 1-4 hours, and the pressure in the column is <1 Pa. Finally, the temperature is reduced to -243--196℃; Step 3: introducing a mixed gas containing any two components of H2, HD, D2, HT, DT and T2 in any proportion into the TCAP device at a pressure of 10-500000 Pa; Step 4: keep the separation temperature at -243 ~ -196℃ for 1 ~ 1000 minutes, increase the temperature to -173 ~ -73℃ at a rate of 2 ~ 20℃ / min, and then decrease the temperature to -243 ~ -196℃ at a rate of 5 ~ 20℃ / min; Step 5: repeat Step 4 for 2 ~ 50 times until the light / heavy component content in the extracted initial mixed gas meets the requirements.

[0041] In the present application, all the preparation raw materials are commercially available products well known to those skilled in the art, unless otherwise specified.

[0042] The present application is described in detail below through examples and experimental examples. However, these are only examples and do not limit the present application in any form.

[0043] Example 1 This example provides an air-stable metal organic framework, comprising the following steps: Step 1: CuCl2, ZnCl2, 1,5-dihydrobenzo[1,2-d:4,5-d']bis([1,2,3]triazole), N,N-dimethylformamide are added to a stainless steel reactor in a molar ratio of 3:2:1:1000, and reacted at 140℃ for 48 hours; Step 2: After the reaction is completed, the reaction is placed in a centrifuge tube and centrifuged at a speed of 3000 r / min for 5 minutes in a centrifuge, and the supernatant is removed. Then, N,N-dimethylacetamide, methanol, and dichloromethane are used to wash, centrifuge, and remove the supernatant 3 times, respectively, to obtain the product.

[0044] Step 3: The product is vacuum dried in a vacuum drying oven at 80℃ for 4 hours to obtain a yellow-brown product, which is Cu I 2(BBTA). Figure 1 The XRD spectrum of Cu I 2(BBTA).

[0045] Example 2 This example provides an air-stable metal organic framework, comprising the following steps: Step 1: CuSO4·5H2O, ZnSO4·H2O, 1,5-dihydrobenzo[1,2-d:4,5-d']bis([1,2,3]triazole), N,N-dimethylformamide are weighed in a molar ratio of 2:1:1:500; Step 2: CuSO4·5H2O and 1,5-dihydrobenzo[1,2-d:4,5-d']bis([1,2,3]triazole) were added into N,N-dimethylformamide, and reacted in a stainless steel reactor at 120℃ for 48 hours. Then ZnSO4·H2O was added into the reacted stainless steel reactor, and reacted at 120℃ for another 48 hours; Step 3: After the reaction was completed, the reaction product was placed into a centrifuge tube, and centrifuged at a speed of 3000 r / min for 5 minutes in a centrifuge. The supernatant was removed, and the product was washed, centrifuged and the supernatant was removed for 3 times using N,N-dimethylacetamide, methanol and dichloromethane respectively to obtain the product; Step 4: The product was vacuum dried in a vacuum drying oven at 80℃ for 4 hours to obtain a yellow-brown product, which was Cu I 2(BBTA).

[0046] Example 3 The present example provides an air-stable metal-organic framework, comprising the following steps: Step 1: Cu(NO3)2·2H2O, 1,5-dihydrobenzo[1,2-d:4,5-d']bis([1,2,3]triazole) and N,N-dimethylformamide were added into a stainless steel reactor at a molar ratio of 3:1:3000, and reacted at 130℃ for 21 days; Step 2: After the reaction was completed, the reaction product was placed into a centrifuge tube, and centrifuged at a speed of 3000 r / min for 5 minutes in a centrifuge. The supernatant was removed, and the product was washed, centrifuged and the supernatant was removed for 3 times using N,N-dimethylacetamide, methanol and dichloromethane respectively to obtain the product; Step 3: The product was vacuum dried in a vacuum drying oven at 80℃ for 4 hours to obtain a yellow-brown product, which was Cu I 2(BBTA).

[0047] Application Example 1 The Cu I 2(BBTA) prepared by the method of Example 1 can be used to separate hydrogen isotopes, which can include the following steps: Step 1: 2 g of the metal-organic framework (Cu I 2(BBTA)) was filled into a reflux column of a thermal cycle adsorption (TCAP) device; Step 2: Activation of the metal-organic framework (Cu I 2(BBTA)): in the reflux column, first increase the temperature to 80℃ at a heating rate of 3℃ / min, and keep vacuum for 1 hour, with the pressure in the column <1 Pa. Then increase the temperature to 180℃ at a heating rate of 3℃ / min, and vacuum activate for 2 hours, with the pressure in the column <1 Pa. Finally, reduce the temperature to -223℃; Step 3: Introduce 10000 Pa of mixed gas with volume ratio of 5D2 / 95H2 into the TCAP device; Step 4: Hold at separation temperature -223°C for 10 minutes, increase the temperature to -73°C at a rate of 5°C / min, then decrease the temperature to -223°C at a rate of 5°C / min; Step 5: Repeat Step 4 for 6 times until the light / heavy component content in the initial mixed gas extracted reaches the requirement. The results are shown in Table 1. Figure 2

[0048] While the embodiments of the application have been illustrated and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the spirit and scope of the application, which is defined by the appended claims and their equivalents.​

Claims

1. An air stable metal organic framework, characterized in that, The metal organic framework is Cu I 2(BBTA).

2. The method of claim 1, wherein the air-stable metal-organic framework is prepared by the method comprising: The preparation method comprises: The copper salt, zinc salt, organic ligand and solvent are subjected to hydrothermal reaction, washing and drying to obtain the metal organic framework; or The copper salt, organic ligand and solvent are subjected to hydrothermal reaction, washing and drying to obtain the metal organic framework.

3. The production method according to claim 2, characterized by, The molar ratio of the copper salt, zinc salt, organic ligand and solvent is 2-15:1-10:1:500-10000; The molar ratio of the copper salt, organic ligand and solvent is 2-15:1:500-10000.

4. The production method according to claim 2, characterized by, The copper salt comprises one or more of CuCl2·xH2O, Cu(NO3)2·xH2O and CuSO4·xH2O, wherein x=0-10; The zinc salt comprises one or more of ZnCl2·xH2O, Zn(NO3)2·xH2O and ZnSO4·xH2O, wherein x=0-10; The organic ligand is 1,5-dihydrobenzo[1,2-d:4,5-d']bis([1,2,3]triazole); The solvent comprises N,N-dimethylformamide and / or N,N-dimethylacetamide.

5. The preparation method according to claim 2, characterized in that, The steps of hydrothermal reaction, washing and drying of the copper salt, zinc salt, organic ligand and solvent comprise: Step 1: reacting the copper salt, zinc salt, organic ligand and solvent at 100-150℃ for 48-168 hours to obtain a reaction product, Step 2: centrifuging the reaction product at a speed of 2000-6000 r / min for 4-8 minutes, removing the supernatant, and then cleaning, centrifuging and removing the supernatant using a detergent to obtain a product; Step 3: Dry the product in a vacuum oven at 60-90 °C for 2-6 hours to obtain Cu I 2(BBTA).

6. The preparation method according to claim 2, characterized in that, The steps of hydrothermal reaction, washing and drying of the copper salt, zinc salt, organic ligand and solvent comprise: Step 1: adding the copper salt and organic ligand to the solvent, reacting at 100-150℃ for 24-72 hours, and then adding the zinc salt and continuing to react at 100-150℃ for 24-72 hours to obtain a reaction product; Step 2: centrifuging the reaction product at a speed of 2000-6000 r / min for 4-8 minutes, removing the supernatant, and then cleaning, centrifuging and removing the supernatant using a detergent to obtain a product; Step 3: Dry the product in a vacuum oven at 60-90 °C for 2-6 hours to obtain Cu I 2(BBTA).

7. The preparation method according to claim 2, characterized in that, The steps of hydrothermal reaction, washing and drying of the copper salt, zinc salt, organic ligand and solvent comprise: Step 1: reacting the copper salt, zinc salt, organic ligand and solvent at 100-150℃ for 48-168 hours to obtain a reaction product, Step 2: centrifuging the reaction product at a speed of 2000-6000 r / min for 4-8 minutes, removing the supernatant, and then cleaning, centrifuging and removing the supernatant using a detergent to obtain a product; Step 3: Dry the product in a vacuum oven at 60-90 °C for 2-6 hours to obtain Cu I 2(BBTA).

8. The method of any one of claims 5-7, wherein the method further comprises, The detergent comprises one or more of N,N-dimethylacetamide, methanol and dichloromethane.

9. Use of the metal organic framework of claim 1 or the metal organic framework obtained by the preparation method of any one of claims 2-8 to separate hydrogen isotope gas.

10. Use according to claim 9, characterized in that, The metal organic framework is used as a filling material of a reflux column of a thermal cycle adsorption device; The separated hydrogen isotope is any two of H2, HD, D2, HT, DT and T2, The separation pressure is 10-500000 Pa and the temperature is -243--196℃. The separation cycle is 2-50 times, and the separation time in a single cycle is 1-1000 minutes. The separation cycle is 2-50 times, and the separation time in a single cycle is 1-1000 minutes.

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