A columnar metal-organic framework material, its preparation method, and its application in oxygen purification.

Abstract

This invention discloses a columnar metal-organic framework material, its preparation method, and its application in oxygen purification. The material has the general structural formula MNi-dabco, where M represents the divalent metal ion Fe. 2+ Co 2+ Ni 2+ Cu 2+ One of the components; Ni represents potassium tetracyanonitrile hydrate; dabco represents the columnar ligand triethylenediamine. The CoNi-dabco of this invention exhibits an Ar adsorption capacity of 7.69 cm³ / g under 298 K and 1 bar conditions, and an IAST selectivity of 1.71 for an Ar / O₂ (5 / 95, v / v) binary mixture. Using this material for dynamic breakthrough separation, high-purity oxygen with a purity exceeding 99.99% can be obtained in one step from an Ar / O₂ (5 / 95, v / v) mixture, with an oxygen yield exceeding 6.08 L / kg, demonstrating significant potential for industrial application.

Description

Technical Field

[0001] This invention belongs to the field of porous materials technology, specifically relating to a columnar metal-organic framework material, its preparation method, and its application in oxygen purification. Background Technology

[0002] Oxygen extraction from the air is a crucial step in the separation process of the chemical industry. Global annual oxygen consumption reaches 8 billion tons, and oxygen is widely used in metallurgy, medicine, welding, aerospace, and other fields. Although the traditional chemical industry can meet most of its needs with low-purity oxygen, the requirements for oxygen purity in high-end equipment manufacturing and the medical industry are continuously increasing. For example, medical oxygen needs to reach a purity of ≥99.5%, and the semiconductor industry even requires 99.999999% (9N) or higher.

[0003] Currently, industrial-scale air separation oxygen production processes mainly employ cryogenic distillation technology. The principle behind this is that air containing 78% nitrogen, 21% oxygen, and 0.93% argon is used as the oxygen-producing feedstock, and separation is based on the differences in the boiling points of the air components. However, because the boiling points of the three components are relatively similar (Ar: 87.27 K, O2: 90.17 K, N2: 77.35 K), the separation process is extremely energy-intensive. Producing one ton of 95% pure oxygen can consume 220 to 270 kilowatt-hours of energy.

[0004] Compared to other methods, Pressure Swing Adsorption (PSA) offers superior energy efficiency and is suitable for small to medium-scale oxygen production. The adsorbent is the key component in PSA for oxygen separation. This is because O2 and Ar differ in molecular size (Ar: 3.76 × 3.76 × 3.76 ų, O2: 4.27 × 3.04 × 3.04 ų) and polarizability (Ar: 16.41 × 10⁻⁶). -25 cm³, O2: 15.81 × 10 -25 Ar and O2 molecules (in cm³) have highly similar physicochemical properties, and Ar, as a monatomic inert gas, has a much lower polarizability than the diatomic O2 molecule. This results in a weaker ability for Ar to form induced dipole interactions with the adsorbent surface, making it difficult for existing adsorbents to effectively separate the two. Consequently, it is difficult to completely remove approximately 5% of argon from the oxygen produced by PSA. Therefore, developing novel adsorbent materials that combine high Ar / O2 selectivity, excellent stability, and ease of molding and processing is crucial for advancing the PSA method for producing high-purity oxygen.

[0005] Currently, although a few silver ion exchange zeolites can selectively adsorb argon, their argon adsorption capacity is still at a moderate level. For example, AgA, AgZSM-5, Ag-ETS-10 and Ag / NaY (G. Sethia, RS Pillai, GPDangi, RS Somani, HC Bajaj, RV Jasra, Ind. Eng. Chem. Res. 2010, 49,2353-2362; A. Dudoladov, M. Alekhina, A. Revina, O. Souvorova, BIO Web Conf.2021, 30; A. Ansón, SM Kuznicki, T. Kuznicki, T. Haastrup, Y. Wang, CCH Lin, JA Sawada, EM Eyring, D. Hunter, Microporous Mesoporous Mater.2008, 109, 577-580; J. Sebastian, RV Jasra, Ind. Eng. Chem. Res. 2005, Materials such as 44,8014-8024. have relatively high argon / oxygen selectivity. Among them, Kuznicki et al. studied Ag⁺ ion-exchanged zeolites (Ag-ETS-10 and Ag-mordenite). At 30°C and 1.19 bar, Ag-ETS-10 achieved a Henry selectivity of 1.49 for Ar / O₂, which is about 16% higher than that of Ag-mordenite (1.25). However, silver-based materials have the disadvantages of high cost and insufficient stability, and are easily reduced under light or high temperature conditions.

[0006] MOF adsorbents have advantages such as good structural tunability, easy adsorption-desorption-regeneration, and flexible structural control, and are widely used to identify and separate gas mixtures with similar properties. Further exploration of their application potential in Ar / O2 adsorption and separation aims to enhance the recognition and adsorption of Ar by adjusting the matched pore structure and adding specific binding sites. For example, materials such as Al-FUM and TYUT-20 (Zhao S, Lin D, Yao J. Chemical Engineering Science, 2025, 318:122130; Liu P, Li J, Yan F. Angewandte Chemie International Edition, 2025, 64(25): e202504324.) exhibited an Ar adsorption capacity as high as 14.5 cm³ / g and an Ar / O2 selectivity of 1.54 under conditions of 298 K and 1 bar, demonstrating better Ar / O2 separation performance. However, existing adsorbents have disadvantages in terms of stability and environmental tolerance. Directly synthesized MOF powder cannot be used directly in industrial applications of pressure swing adsorption (PSA) because directly packing MOF powder into adsorption columns often leads to problems such as high system pressure drop, low mass transfer rate, poor MOF recyclability, and easy powder dispersion. In order for MOF to be safely and stably used in industrial production, it is necessary to process it into MOF particles with a certain compressive strength while retaining its original adsorption properties through molding processes. Summary of the Invention

[0007] The purpose of this invention is to overcome the technical defects of existing adsorbents, such as low selectivity, poor stability and difficulty in molding, and to provide a columnar metal-organic framework material with high Ar / O2 selectivity, its preparation method and application.

[0008] The objective of this invention is achieved through the following technical solutions.

[0009] A columnar metal-organic framework material is a solid crystalline material with a three-dimensional network structure, and its general structural formula is MNi-dabco, where M represents the divalent metal ion Fe. 2+ Co 2+ Ni 2+ Cu 2+ One of them; Ni represents potassium tetracyanonickel hydrate; dabco represents the columnar ligand triethylenediamine.

[0010] The preparation method of the columnar metal-organic framework material described above includes the following steps:

[0011] (1) Mix the metal salt with [Ni(CN)4] 2-Add to deionized water and stir until completely dissolved to obtain mixture A;

[0012] (2) Dissolve the ligand in a mixed solvent of methanol and deionized water to obtain mixture B;

[0013] (3) The mixture B is slowly added to the mixture A, and the mixture is stirred to react and a solid precipitate is obtained;

[0014] (4) The obtained solid precipitate is separated by centrifugation, washed with anhydrous ethanol and dried to obtain the columnar metal-organic framework material.

[0015] Preferably, the metal ion in the metal salt of step (1) is Fe. 2+ Co 2+ Ni 2+ Cu 2+ One of them.

[0016] Preferably, the metal salt and [Ni(CN)4] in step (1) 2- The molar ratio is 1:1 to 1:4.

[0017] Preferably, the ligand in step (2) is triethylenediamine.

[0018] Preferably, the volume ratio of mixture B and mixture A in step (3) is 1:2 to 1:10.

[0019] Preferably, the stirring reaction in step (3) is carried out at a temperature of 25-50°C for 3-12 hours.

[0020] Preferably, the stirring speed in step (3) is 100-800 r / min.

[0021] Preferably, in step (4), the material obtained in step (3) is collected and transferred to anhydrous ethanol for soaking for three days, during which the solvent is exchanged more than three times a day, and then activated at 393K for 8-12 hours at a degassing station to obtain activated material.

[0022] Preferably, the divalent metal ion is Co. 2+ The ligand is triethylenediamine (dabco), and the tetracyanometallic acid ion is K2[Ni(CN)4]. The preparation method is as follows: a methanol / deionized water mixture containing triethylenediamine is added dropwise to an aqueous solution containing Co(NO3)2·6H2O and K2[Ni(CN)4]. The mixture is stirred at 313K for 3 hours. After centrifugation, washing, and drying, CoNi-dabco material is obtained.

[0023] The above-described columnar metal-organic framework material is used in oxygen purification. When the material is used as an adsorbent and comes into contact with a mixed gas containing argon and oxygen, it preferentially and selectively adsorbs and separates argon from the mixed gas, thereby achieving efficient adsorption and separation of argon and oxygen.

[0024] Preferably, the volume ratio of argon to oxygen in the mixed gas is 50:50 to 5:95; the separation temperature is 195K to 308K, and the gas pressure is 1 to 100 kPa.

[0025] More preferably, the volume ratio of argon to oxygen in the mixed gas is 5:95; the separation temperature is 298K and the gas pressure is 100 kPa.

[0026] The material of this invention has one-dimensional gourd-shaped ultramicropores and high-density open metal sites, and exhibits excellent Ar selective adsorption capacity through the synergy of pore size confinement effect and induced dipole effect.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) The CoNi-dabco material of this invention has a unique combination of "pillar-layer structure + open metal sites". The abundant methylene groups on the three-dimensional dabco pillars in the channels provide van der Waals forces, and the uniformly distributed ultramicropore size (~4.6 Å) is highly matched with the size of Ar atoms. The construction of a one-dimensional gourd-shaped channel morphology not only strengthens the channel constraint, but also produces a confinement effect; while the adjacent open metal sites between the pillars can induce dipole interactions with Ar atoms. The synergistic effect of the two significantly enhances the adsorption affinity for inert Ar molecules, thereby endowing the material with high Ar / O2 selectivity.

[0029] (2) The material of this invention achieves excellent Ar / O2 separation performance. The CoNi-dabco component exhibits an Ar adsorption capacity of 7.6 cm⁻¹ at 298 K and 1 bar. 3 / g, with an IAST selectivity of 1.71 for Ar / O2 (5 / 95), which is superior to existing reported materials.

[0030] (3) The activated columnar metal-organic framework material of this invention achieves adsorption and separation of Ar / O2 under dynamic conditions, and can separate high-purity oxygen with a purity higher than 99.99% in one step, with an oxygen yield as high as 6.08 L / kg. Furthermore, the material maintains structural and performance stability during multiple adsorption-desorption cycles. It can also be recycled after helium purging, offering advantages such as energy saving, environmental protection, and simple operation.

[0031] (4) The columnar metal-organic framework material used in this invention has excellent chemical stability. Its crystal structure and pore volume can still be maintained after soaking in water for 2 weeks and after soaking in various organic reagent aqueous solutions, which can meet the environmental requirements for Ar / O2 separation.

[0032] (5) The columnar metal-organic framework material used in this invention achieves MOF powder molding through processes such as tableting. The compressive strength of the molded particles meets industrial requirements (>20 N) and retains the high adsorption activity of the original powder. Combined with its many advantages such as ultra-high Ar / O2 separation selectivity, ultra-high chemical stability and easy large-scale preparation, it has become a promising adsorption material in the field of ultrapure oxygen preparation. Attached Figure Description

[0033] Figure 1 These are the synthetic raw materials and columnar structure diagrams of the metal-organic frameworks prepared in Examples 1-4 of this invention.

[0034] Figure 2 These are powder diffraction patterns of the materials prepared in Examples 1-4 of this invention.

[0035] Figure 3 The CO2 adsorption isotherm and pore size distribution of the material prepared in Example 1 of this invention at 195K.

[0036] Figure 4 The single-component adsorption isotherms of Ar and O2 at 298 K for the materials prepared in Examples 1-4 and Comparative Examples 1-2 of this invention.

[0037] Figure 5 The material prepared in Example 1 of this invention exhibits IAST selectivity for Ar / O2 (5 / 95) at 298K.

[0038] Figure 6 The material prepared in Example 1 of this invention exhibits the same heat of adsorption (Qst) for Ar and O2 at 298 K.

[0039] Figure 7 This is a breakthrough adsorption diagram of the material prepared in Example 1 of the present invention for an Ar / O2 (5 / 95, v / v) mixture at 298K.

[0040] Figure 8 PXRD patterns of the material prepared in Example 1 of this invention immersed in different humidity and pH conditions.

[0041] Figure 9 A 10-cycle Ar adsorption-desorption diagram of the material prepared in Example 1 of this invention.

[0042] Figure 10The morphology and size of the shaped particles of the material prepared in Example 1 of this invention are as follows: (a) calcium alginate method; (b) extrusion bonding method; (c) tableting method.

[0043] Figure 11 The material prepared in Example 1 of this invention was molded by tableting and the single-component adsorption isotherms of Ar and O2 at 298K were obtained; wherein (a)-(d) correspond to the adsorption isotherms after adding carboxymethyl cellulose (CM), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose (HPC) and hydroxypropyl methyl cellulose (HPMC) binders, respectively. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the present invention is not limited to the following embodiments.

[0045] Example 1:

[0046] CoNi-dabco powder synthesis: Co(NO3)2·6H2O (1 mmol, 291.03 mg) and K2[Ni(CN)4]·nH2O (1 mmol, 240 mg) were added to 4 mL of deionized water and stirred for 30 min. Then, 20 mL of a methanol / deionized water (1 / 1, v / v) mixture containing triethylenediamine (1 mmol, 110 mg) was slowly added to the above solution. The mixture was stirred at 313 K for 3 h, producing a large amount of pink precipitate. The sample was collected by centrifugation and washed with anhydrous ethanol for 3 days, and then activated at 393 K for 12 h in a vacuum degassing station to obtain activated CoNi-dabco powder material.

[0047] Scale-up synthesis of CoNi-dabco material: Co(NO3)2·6H2O (5.82 g) and K2[Ni(CN)4]·nH2O (4.80 g) were added to 80 mL of deionized water and stirred for 30 min. Then, 400 mL of a methanol / water (1 / 1, v / v) mixture containing triethylenediamine (2.20 g) was slowly added to the above solution. The mixture was stirred at 313 K for 3 h, resulting in a pink solid precipitate. The sample was collected by centrifugation, washed with anhydrous ethanol for 3 days, and then activated at 393 K for 12 h in a vacuum degassing station to obtain the scaled-up CoNi-dabco material.

[0048] Example 2:

[0049] Synthesis of NiNi-dabco material: Ni(NO3)2·6H2O (1 mmol, 290.79 mg) and K2[Ni(CN)4]·nH2O (1 mmol, 240 mg) were added to 4 mL of deionized water and stirred for 30 min. Then, 20 mL of a methanol / deionized water (1 / 1, v / v) mixture containing triethylenediamine (1 mmol, 110 mg) was slowly added to the above solution. The mixture was stirred at 313 K for 3 h, resulting in a solid precipitate. The sample was collected by centrifugation and washed with anhydrous ethanol for 3 days, and then activated at 393 K for 12 h in a vacuum degassing station to obtain the activated NiNi-dabco material.

[0050] Example 3:

[0051] Synthesis of CuNi-dabco material: Cu(NO3)2·3H2O (1 mmol, 241.6 mg) and K2[Ni(CN)4]·nH2O (1 mmol, 240 mg) were added to 4 mL of deionized water and stirred for 30 min. Then, 20 mL of a methanol / deionized water (1 / 1, v / v) mixture containing triethylenediamine (1 mmol, 110 mg) was slowly added to the above solution. The mixture was stirred at 313 K for 3 h, resulting in a solid precipitate. The sample was collected by centrifugation and washed with anhydrous ethanol for 3 days, and then activated at 393 K for 12 h in a vacuum degassing station to obtain the activated CuNi-dabco material.

[0052] Example 4:

[0053] Synthesis of FeNi-dabco material: Fe(NO3)3·9H2O (1 mmol, 404 mg) and K2[Ni(CN)4]·nH2O (1 mmol, 240 mg) were added to 4 mL of deionized water and stirred for 30 min. Then, 20 mL of a methanol / deionized water (1 / 1, v / v) mixture containing triethylenediamine (1 mmol, 110 mg) was slowly added to the above solution. The mixture was stirred at 313 K for 3 h, resulting in a solid precipitate. The sample was collected by centrifugation and washed with anhydrous ethanol for 3 days, and then activated at 393 K for 12 h in a vacuum degassing station to obtain the activated FeNi-dabco material.

[0054] Comparative Example 1:

[0055] Synthesis of ZJU-74-Ni material: A 1 mmol aqueous solution of K2[Ni(CN)4]·nH2O (4 mL) was added to a 1 / 1, 20 mL methanol / water solution of Co(NO3)2·6H2O (1 mmol) and pyrazine (pyz, 1 mmol). The mixture was stirred continuously at 313 K for 3 hours to obtain a light pink precipitate. Fresh powder samples were subjected to solvent exchange with methanol at least 10 times over two days, followed by vacuuming at room temperature for 24 hours, and then vacuuming at 393 K for 12 hours to obtain the activated CoNi-pyz material.

[0056] Comparative Example 2:

[0057] ZJU-74a-Pd: 2 mL of a 0.5 mmol K2[Pd(CN)4]·nH2O aqueous solution was added to a 1 / 1, 10 mL methanol / water solution of 0.5 mmol Co(NO3)2·6H2O and 0.5 mmol pyrazine (pyz, 0.5 mmol). The mixture was stirred at 313 K for 3 h to obtain a pale pink precipitate. Fresh powder samples were first exchanged with dry acetone at least 10 times over two days, then vacuumed at room temperature for 24 h, followed by vacuuming at 393 K for 12 h to obtain activated ZJU-74a-Pd material.

[0058] Structural characterization and performance testing:

[0059] The schematic diagram of the synthesis route and crystal structure of the obtained material is as follows: Figure 1 As shown, in the columnar metal-organic framework material, tetracyanometallic acid ions coordinate with four divalent metal ions through four cyano groups to form a two-dimensional planar structure; triethylenediamine coordinates with two divalent metal ions longitudinally through two nitrogen atoms, acting as pillars to connect the two-dimensional plane to form a three-dimensional structure. The PXRD results in Figure 2 confirm that the materials prepared in Examples 1-4 have clear diffraction peak positions and are free of impurities, indicating that the materials have good crystallinity and phase purity.

[0060] The specific surface area and pore size distribution of an adsorbent are key indicators determining its separation performance. For example... Figure 3 As shown, the BET specific surface area of ​​the CoNi-dabco material is 224 m² / g based on CO₂ adsorption-desorption tests at 195 K. 2 / g, calculated using the Horvath-Kawazoe model, shows a concentrated pore size distribution of 4.6 Å, which is highly consistent with Ar atoms.

[0061] The adsorption performance of Examples 1-4 and Comparative Examples 1-2 for Ar and O2 was tested at 298 K and 1 bar. The adsorption isotherms are as follows: Figure 4As shown in (a) to (f) in the figure. Based on the adsorption data, the adsorption efficiency of the Ar / O2 mixture (temperature v / v) in Example 1 at 100 kPa was calculated. IAST selectivity is 1.71 ( Figure 5 ).like Figure 6 As shown, the isotropic adsorption heats of CoNi-dabco for Ar and O2 were further calculated using the Clausius-Clapeyron equation to be 18.59 kJ / mol and 16.15 kJ / mol, respectively, confirming that it has a stronger adsorption affinity for Ar molecules.

[0062] Table 1 summarizes the Ar adsorption capacity and Ar / O2 IAST selectivity of Examples 1-4, Comparative Examples 1-2, and previously reported materials at 298 K and 100 kPa. As shown in Table 1, compared with other previously reported materials, CoNi-dabco achieves better Ar / O2 selectivity while maintaining a high Ar adsorption capacity.

[0063] Table 1

[0064]

[0065] [1]ND Hutson, SU Rege, RT Yang, AIChE J. 1999, 45, 724-734.

[0066] [2]RV Afonso, J. Durão, A. Mendes, AM Damas, L. Gales, Angew. Chem., Int. Ed. 2010, 49, 3034-3036.

[0067] [3]G. Sethia, RS Pillai, GP Dangi, RS Somani, HC Bajaj,RV Jasra, Ind. Eng. Chem. Res. 2010, 49, 2353-2362.

[0068] [4]Z. Bao, L. Yu, T. Dou, Y. Gong, Q. Zhang, Q. Ren, X. Lu, S. Deng,J. Chem. Eng. Data 2011, 56, 4017-4023.

[0069] [5]A. Dudoladov, M. Alekhina, A. Revina, O. Souvorova, BIO Web Conf.2021, 30.

[0070] [6]A. Ansón, SM Kuznicki, T. Kuznicki, T. Haastrup, Y. Wang, CCH Lin, JA Sawada, EM Eyring, D. Hunter, Microporous Mesoporous Mater.2008, 109, 577-580.

[0071] [7]J. Sebastian, RV Jasra, Ind. Eng. Chem. Res. 2005, 44, 8014-8024.

[0072] [8] Zhao S, Lin D, Yao J. Chemical Engineering Science.2025, 318:122130.

[0073] [9] Liu P, Li J, Yan F. Angewandte Chemie International Edition.2025,64(25):e202504324.

[0074] Figure 7 Figure (a) shows the dynamic breakthrough curve of CoNi-dabco for an Ar / O2 (5 / 95, v / v) mixture at 298 K. The results show that O2 rapidly penetrated within 3 minutes and quickly reached adsorption equilibrium, while Ar only began to penetrate after approximately 8 minutes, indicating the excellent dynamic separation performance of CoNi-dabco for the Ar / O2 (5 / 95, v / v) binary mixture. Furthermore, calculations showed that oxygen with a purity greater than 99.99% could be produced from the Ar / O2 (5 / 95, v / v) binary mixture in a single adsorption cycle, with a production rate of 6.08 L / kg. After adsorption equilibrium was reached in each breakthrough experiment, the adsorbent was regenerated by purging the adsorption column in situ at room temperature with helium at a flow rate of 10 mL / min. The results are shown below. Figure 7 As shown in (b), five consecutive cycles of adsorption-desorption breakthrough experiments confirmed that CoNi-dabco has excellent regeneration performance and cycle stability.

[0075] Figure 8As shown, under various pH conditions, various humid environments, and after adsorption / breakthrough tests, the XRD patterns of CoNi-dabco still basically match the simulated patterns, with clear characteristic peaks (12.5° and 17.7°) and no obvious impurity peaks, indicating that the material structure remains stable. Figure 9 The results showed that the scaled-up synthesized CoNi-dabco material maintained an adsorption capacity of 7.69 cm⁻¹ for Ar under conditions of 298 K and 1 bar. 3 / g, after 10 cycles of adsorption and desorption, the working capacity showed no significant decrease.

[0076] To investigate the effects of molding process and binder on MOF adsorption performance, commonly used industrial binders such as calcium alginate (CA), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), and hydroxypropyl methyl cellulose (HPMC) were examined. Three types of CoNi-dabco molded particles were prepared using the calcium alginate method, extrusion bonding method, and tableting method, respectively, with morphologies as shown in the figure. Figure 10 As shown, the compressive strength of the three types of molded particles was tested 10 times using a KD-4 particle compressive strength tester. The results showed that the average strength of the particles formed by the tableting method better met the requirements of industrial adsorbent applications (>20 N), and therefore they were selected for subsequent adsorption performance testing.

[0077] In the tableting process, four binders—carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), and hydroxypropyl methyl cellulose (HPMC)—were systematically screened, and eight different CoNi-dabco granules were prepared by adding them at proportions of 5% and 10%, respectively. Figure 11 As shown, the Ar adsorption capacity of all compressed particles remained good compared to the original powder material. With the increase of binder addition, the adsorption capacity showed a slight decreasing trend, but all compressed particles generally retained the adsorption performance of the original CoNi-dabco powder material well.

[0078] In summary, this invention successfully synthesized a CoNi-dabco material with a synergistic effect of columnar structure and open metal sites. Utilizing the unique pore confinement effect and the CH groups on the dabco pillars, it achieves efficient recognition and capture of the inert gas Ar. Combined with its excellent selectivity, thermal stability, and ease of molding, this material has broad application prospects in the field of ultrapure oxygen preparation.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any modifications, equivalent substitutions, or improvements made within the spirit and scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A columnar metal-organic framework material, characterized in that, Its general structural formula is MNi-dabco, where M represents the divalent metal ion Fe. 2+ Co 2+ Ni 2+ Cu 2+ One of them; Ni represents potassium tetracyanonickel hydrate; dabco represents the columnar ligand triethylenediamine.

2. A method for preparing a columnar metal-organic framework material as described in claim 1, characterized in that, Includes the following steps: (1) Mix the metal salt with [Ni(CN)4] 2- Add to deionized water and stir until completely dissolved to obtain mixture A; (2) Dissolve the ligand in a mixed solvent of methanol and deionized water to obtain mixture B; (3) The mixture B is slowly added to the mixture A, and the mixture is stirred to react and a solid precipitate is obtained; (4) The obtained solid precipitate is separated by centrifugation, washed with anhydrous ethanol and dried to obtain the columnar metal-organic framework material.

3. The method for preparing the columnar metal-organic framework material according to claim 2, characterized in that, The metal ion in the metal salt described in step (1) is Fe. 2+ Co 2+ Ni 2+ Cu 2+ One of them.

4. The method for preparing the columnar metal-organic framework material according to claim 2, characterized in that, The metal salt and [Ni(CN)4] mentioned in step (1) 2- The molar ratio is 1:1 to 1:

4.

5. The method for preparing the columnar metal-organic framework material according to claim 2, characterized in that, The ligand in step (2) is triethylenediamine.

6. The method for preparing the columnar metal-organic framework material according to claim 2, characterized in that, In step (3), the volume ratio of mixture B to mixture A is 1:2 to 1:

10.

7. The method for preparing the columnar metal-organic framework material according to claim 2, characterized in that, The stirring reaction in step (3) is carried out at a temperature of 25-50℃ for 3-12 hours.

8. The method for preparing the columnar metal-organic framework material according to claim 2, characterized in that, The stirring speed in step (3) is 100-800 r / min.

9. The application of the columnar metal-organic framework material according to claim 1 in oxygen purification, characterized in that, When the material is used as an adsorbent and comes into contact with a mixed gas containing argon and oxygen, it preferentially and selectively adsorbs and separates argon from the mixed gas, thereby achieving efficient adsorption and separation of argon and oxygen.

10. The application of the columnar metal-organic framework material according to claim 9 in oxygen purification, characterized in that, The volume ratio of argon to oxygen in the mixed gas is 50:50 to 5:95; the separation temperature is 195K to 308K, and the gas pressure is 1 to 100 kPa.

Images