Preparation method of high crystallinity MOF-801 and application thereof in separation of C3F8

Abstract

The application discloses a preparation method of high-crystallinity MOF-801 and application of the MOF-801 in separation of C3F8 and belongs to the technical field of adsorption separation. The MOF-801 has a regular microporous structure and extremely high crystallinity, can realize efficient screening separation of C3F8 in a binary C3F6 / C3F8 mixture, can also realize one-step high-purity separation of C3F8 in a ternary CF4 / C2F6 / C3F8 mixture, and the purity of the product can reach more than 99.999 %. In addition, the material also has excellent acid-base stability, water stability and cyclic regeneration capacity, can realize large-scale preparation through normal-pressure reflux reaction, the separation performance of the large-scale preparation sample is consistent with that of a small-scale sample, and the industrialization is possible.

Description

Technical Field

[0001] This invention belongs to the field of adsorption separation technology, and specifically relates to a method for preparing highly crystalline MOF-801 and its application in the separation of C3F8. Background Technology

[0002] Electronic specialty gases are indispensable raw materials in semiconductor manufacturing, with applications covering photolithography, etching, thin film deposition, ion implantation, and cavity cleaning. Perfluoropropane (C3F8), as one of the core electronic specialty gases, is widely used in plasma etching and cleaning processes in integrated circuit manufacturing due to its excellent chemical stability, high plasma etching selectivity, low global warming potential (GWP), and low toxicity. With the continuous improvement of integrated circuit integration density, the demands of precision manufacturing place stringent requirements on the purity of perfluoropropane, requiring a purity of 99.999% (5N) or higher. Industrially, perfluoropropane is typically prepared from hexafluoropropylene (C3F6) via a fluorination addition reaction. This process inevitably leaves unreacted hexafluoropropylene impurities. Another preparation method involves the direct reaction of carbon with fluorine gas, but this route generates byproducts such as carbon tetrafluoride (CF4) and hexafluoroethane (C2F6), which need to be removed. Therefore, separation of the C3F6 / C3F8 mixed system and the CF4 / C2F6 / C3F8 mixed system is necessary to obtain high-purity electronic-grade C3F8. However, traditional cryogenic distillation processes are not only energy-intensive and costly, but also have low separation efficiency. In summary, there is an urgent need to develop energy-saving physical adsorption separation technology based on novel porous materials to meet the growing demand for high-purity electronic specialty gases in high-end manufacturing.

[0003] Metal-organic frameworks (MOFs) allow for precise control of framework structure, pore size, and functional sites at the molecular scale, enabling them to exhibit excellent separation performance in various gas separation scenarios. Significant progress has been made in olefin / alkane separation, isomer separation, and carbon dioxide capture. However, research on the separation and purification of C3F6 / C3F8 is limited, and there are no studies on the one-step purification of C3F8 from a ternary mixture of CF4 / C2F6 / C3F8. Although C3F6 / C3F8 can be separated based on differences in adsorption affinity or diffusion rate, co-adsorption is highly likely, typically resulting in low separation selectivity and poor separation efficiency, failing to meet the high purity requirements of perfluoropropane in integrated circuit manufacturing. In contrast, molecular sieve separation based on molecular size sieving effects theoretically achieves infinitely high separation selectivity, significantly suppresses co-adsorption, and possesses highly efficient gas separation capabilities, making it highly suitable for the purification of electronic specialty gases. Therefore, this invention studies MOFs to achieve the goal of obtaining high purity C3F8 in binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures. Summary of the Invention

[0004] To address the technical problems of high cost, high energy consumption, and low purity in traditional C3F8 purification methods, this invention provides a method for preparing high-crystallinity MOF-801 and its application in the separation of C3F8. The high-crystallinity MOF-801 can achieve one-step high-purity sieve separation of C3F8 in binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures.

[0005] This invention is achieved through the following technical solution: Application of a highly crystallinity MOF-801 in the separation of C3F8.

[0006] Preferably, the high crystallinity MOF-801 can achieve efficient sieving and separation of binary C3F6 / C3F8 mixtures.

[0007] Preferably, the high crystallinity MOF-801 can achieve one-step high-purity sieving separation of C3F8 in a ternary CF4 / C2F6 / C3F8 mixture.

[0008] The present invention also provides a method for preparing the highly crystallinity MOF-801, comprising the following steps: Zirconium oxychloride octahydrate metal salt and fumaric acid ligand were dissolved in N,N-dimethylformamide (DMF) solvent. The solid was sonicated to completely dissolve, anhydrous formic acid was added, and the mixture was stirred and mixed evenly. The mixture was then reacted in a hydrothermal reactor at 120°C for 24 hours. After filtration, the solid product was washed alternately with DMF and methanol and then dried under vacuum at 120°C for 10 hours to obtain the highly crystalline MOF-801.

[0009] Preferably, the molar ratio of fumaric acid to zirconium oxychloride octahydrate is 1:1, the addition ratio of anhydrous formic acid to fumaric acid is 2.64 mL: 0.7 mmol, and the volume ratio of anhydrous formic acid to DMF is 1.32: 9.

[0010] The present invention also provides a method for large-scale preparation of the highly crystallinity MOF-801, comprising the following steps: Fumaric acid ligand and zirconium oxychloride octahydrate were dissolved in DMF solvent, and the solid was completely dissolved by ultrasonic treatment. Anhydrous formic acid was added, and the mixture was refluxed at 120°C under normal pressure for 24 h. After filtration, the solid product was washed alternately with DMF and methanol, and then dried under vacuum at 120°C for 10 h to obtain high crystallinity MOF-801.

[0011] Preferably, the molar ratio of fumaric acid to zirconium oxychloride octahydrate is 1:1; the volume ratio of anhydrous formic acid to DMF is 0.16:1.08; and the addition ratio of anhydrous formic acid to fumaric acid is 0.08L:21mmol.

[0012] Preferably, the highly crystallinity MOF-801 can be recycled during gas separation.

[0013] Beneficial technical effects of the present invention: (1) The existing mainstream MOF separation mechanisms are divided into three categories, all of which have inherent defects: Affinity recognition type: Relying on the formation of hydrogen bonds between hydroxyl groups and formate groups in the pores and C3F6, selective adsorption is achieved through electrostatic interactions. C3F8 flows out through weak interactions and is easily affected by gas humidity and impurities. Co-adsorption is aggravated under high concentration conditions. Flexible gating type: Relying on the temperature response of pore opening and closing caused by ligand torsion to achieve sieving. The flexibility of the framework will lead to pore size drift during the circulation process, and the selectivity will decay after long-term use. Fluorinated modification type: Post-modification is required to introduce trifluoromethyl to regulate the window. The synthesis steps are many and the raw material cost is high. The modified groups are easy to fall off and become ineffective. This invention utilizes a rigid intrinsic micropore size exclusion mechanism for high-crystallinity MOF-801, eliminating the need for flexible structures or additional functional group modifications. Formic acid is used as a regulator to precisely enhance the long-range order of the crystals, eliminating the wide distribution of defective pores in low-crystallinity materials and forming uniformly sized, rigid, and stable 6-8 Å micropore windows. Small molecules such as CF4, C2F6, and C3F6 can freely enter the pores and be adsorbed and retained, while the larger C3F8 is completely physically blocked by the rigid pore windows. There is no co-adsorption of two perfluorinated molecules throughout the process, and the sieving selectivity approaches the theoretical limit, fundamentally different from existing separation mechanisms that rely on intermolecular forces and framework deformation. Furthermore, this invention pioneers a one-step separation technique for ternary perfluorinated gas mixtures using MOF-801, filling a research gap in the purification of electronic specialty gases using this classic zirconium-based MOF and expanding the application scenarios of MOF-801.

[0014] (2) The highly crystalline MOF-801 prepared in this invention has a highly uniform microporous structure (pore size concentrated in the range of 6-8 Å). This single and narrow pore size distribution endows the material with excellent molecular sieving effect: First, due to its precise size exclusion capability, C3F8 molecules cannot enter the uniform microporous channels due to their large kinetic diameter, and are thus completely excluded from the channels, achieving an extremely low adsorption capacity (only 0.26 cm at 298 K and 1 bar). 3 (g); Secondly, smaller impurity molecules such as C3F6 and C2F6 can smoothly enter the pores and be preferentially adsorbed, achieving efficient capture, thus separating C3F8 from the mixed gas efficiently and with high purity in one step; more importantly, the uniform pore size fundamentally eliminates the non-selective adsorption caused by excessively large local pores, completely solving the problem of co-adsorption of C3F6 and C3F8, which is a technical bottleneck that is difficult to overcome in dual-pore or hierarchical porous materials. In summary, this invention achieves a high degree of uniformity in the pore size of MOF-801 by controlling the synthesis conditions (especially the amount of formic acid regulator), thereby obtaining molecular sieving accuracy far exceeding that of conventional porous materials, providing a new technical route for the green and low-cost preparation of electronic-grade high-purity C3F8.

[0015] (3) The high crystallinity MOF-801 of the present invention has a regular microporous structure and extremely high crystallinity. It can efficiently separate C3F8 in the binary C3F6 / C3F8 mixed system by means of sieving effect, eliminate co-adsorption and obtain extremely high separation selectivity. It can also separate C3F8 with a purity of more than 99.999% from the CF4 / C2F6 / C3F8 ternary mixed gas in one step, which fully meets the standards for electronic grade high-purity C3F8. At the same time, the material has outstanding acid and alkali stability and water stability. The crystal structure can be maintained intact after soaking in different pH solutions for 72 hours and in pure water for 30 days. After multiple adsorption-desorption and breakthrough separation cycles, the adsorption capacity and separation performance have no significant decay. The recycling performance is excellent. It can be prepared on a large scale by atmospheric pressure reflux process. The separation performance of the scaled-up product is consistent with that of the small-scale sample. Overall, it has excellent prospects for industrial application. Attached Figure Description

[0016] Figure 1 Powder X-ray diffraction (PXRD) of the sample in Example 1. Figure 2 The isotherm of N2 adsorption and desorption at 77 K for the sample of Example 1; Figure 3 The image shows a scanning electron microscope (SEM) image of the sample from Example 1. Figure 4 The adsorption isotherms of C3F6 and C3F8 for the sample in Example 1 at 298 K are shown. Figure 5 The adsorption isotherms of CF4, C2F6 and C3F8 in the sample of Example 1 at 298 K; Figure 6 The transmission curve of the sample in Example 1 to C3F6 / C3F8 at 298K; Figure 7 The transmission curve of the sample in Example 1 to CF4 / C2F6 / C3F8 at 298K; Figure 8 The above are PXRD comparison images of the sample from Example 1 after soaking in solutions of different pH values ​​for 72 hours. Figure 9 This is a comparison of PXRD patterns of the sample from Example 1 after soaking in deionized water for 30 days; Figure 10 This is a cycle diagram of the adsorption isotherm of C3F6 on the sample of Example 1 at 298K; Figure 11 This is a breakthrough separation cycle diagram of the sample in Example 1 for C3F6 / C3F8; Figure 12 Image of the sample prepared in Example 2; Figure 13 PXRD of the sample from Example 2; Figure 14 The isotherm of N2 adsorption and desorption at 77 K for the sample in Example 2; Figure 15 The adsorption isotherms of C3F6 and C3F8 for the sample in Example 2 at 298 K are shown. Figure 16 The adsorption isotherms of CF4, C2F6 and C3F8 in the sample of Example 2 at 298 K; Figure 17 This is a 100mL breakthrough column chromatogram of the sample from Example 2; Figure 18 The transmission curve of the sample in Example 2 to C3F6 / C3F8 at 298K; Figure 19 The transmission curve of the sample in Example 2 against CF4 / C2F6 / C3F8 at 298K; Figure 20 Comparison of powder X-ray diffraction (PXRD) images of samples from Comparative Example 1 and Example 1; Figure 21 The image shows a scanning electron microscope (SEM) image of the sample in Comparative Example 1. Figure 22 The N2 adsorption-desorption isotherms for samples of Comparative Example 1 and Example 1 at 77 K; Figure 23 Pore ​​size distribution diagrams of samples from Comparative Example 1 and Example 1; Figure 24 The single-component adsorption isotherms of C3F6 and C3F8 for Comparative Example 1 and Example 1 samples at 298K are shown. Detailed Implementation

[0017] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments. Example 1: Preparation of highly crystallinity MOF-801 by autoclave reaction Fumaric acid ligand (0.7 mmol) and zirconium oxychloride octahydrate (0.7 mmol) were dissolved in 18 mL of N,N-dimethylformamide (DMF) solvent. The mixture was sonicated until the solid was completely dissolved. 2.64 mL of anhydrous formic acid was added, and the mixture was reacted in a hydrothermal reactor at 120 °C for 24 h. After filtration, the sample was washed six times with 30 mL of DMF (for three consecutive days), and then immersed in 50 mL of methanol for seven days (the methanol was replaced twice daily). Finally, the sample was dried under vacuum at 150 °C for 24 h to obtain the zirconium-based metal-organic framework material ND-MOF-801.

[0018] Example 2: Large-scale preparation of highly crystallinity MOF-801 via atmospheric pressure reflux reaction 4.9 g of fumaric acid ligand (42 mmol) and 13.5 g (42 mmol) of zirconium oxychloride octahydrate were dissolved in 1.08 L of DMF solvent. The mixture was sonicated until the solid was completely dissolved. 0.16 L of anhydrous formic acid was added, and the mixture was refluxed at 120 °C under normal pressure for 24 h. After filtration, the sample was washed six times with 30 mL of DMF (for three consecutive days), and then immersed in 50 mL of methanol for seven days (the methanol was replaced twice daily). Finally, the sample was dried under vacuum at 150 °C for 24 h to obtain the zirconium-based metal-organic framework material ND-MOF-801. Sample image shown. Figure 12 As shown.

[0019] Comparative Example 1: Preparation method of low crystallinity MOF-801: ZrOCl2·8H2O (0.7 mmol), fumaric acid (0.7 mmol), DMF (18 mL), and anhydrous formic acid (28 mmol, 1.06 mL) were mixed in a 50 mL PTFE-lined stainless steel autoclave and heated at 120 °C for 24 hours. After cooling to room temperature, the white polycrystalline powder was collected by centrifugation. The obtained sample was washed six times with 30 mL of DMF (for three consecutive days), and then immersed in 50 mL of methanol for seven days (the methanol was replaced twice daily). Finally, it was dried under vacuum at 150 °C for 24 hours to obtain low-crystallinity MOF-801.

[0020] 1. The highly crystalline MOF-801 prepared in Example 1 was characterized. (1) Powder X-ray diffraction characterization A certain amount of the synthetic material ND-MOF-801 from Example 1 was subjected to powder X-ray diffraction testing; the test results are as follows: Figure 1 As shown in the figure, each peak of the XRD of the synthesized ND-MOF-801 corresponds to that of the simulated ND-MOF-801, indicating that ND-MOF-801 has been successfully synthesized.

[0021] (2) Nitrogen adsorption A certain amount of dried sample was weighed and placed in a test tube for vacuum degassing. After degassing was completed, nitrogen adsorption at 77K was tested. Figure 2 The image shows the N2 adsorption and desorption of ND-MOF-801 at 77 K. The material exhibits a typical reversible type I N2 adsorption isotherm, with closed adsorption and desorption branches and no hysteresis, indicating its inherent microporosity characteristics.

[0022] (3) Scanning electron microscope (SEM) Figure 3 The image shows a scanning electron microscope (SEM) image of ND-MOF-801. As can be seen from the image, ND-MOF-801 exhibits a regular polyhedral structure and has extremely high crystallinity.

[0023] 2. The highly crystalline MOF-801 prepared on a large scale in Example 2 was characterized. (1) Powder X-ray diffraction characterization Powder X-ray diffraction (PXRD) was performed on the ND-MOF-801 synthesized on a large scale in Example 2; the test results are as follows: Figure 13 As shown, the XRD patterns of the large-scale synthesized ND-MOF-801 correspond to each peak of the XRD patterns of the small-scale synthesized ND-MOF-801, indicating that the large-scale synthesized ND-MOF-801 has been successfully synthesized.

[0024] (2) Nitrogen adsorption A certain amount of dried sample was weighed and placed in a test tube for vacuum degassing. After degassing was completed, nitrogen adsorption at 77K was tested. Figure 14 The image shows the N2 adsorption and desorption of ND-MOF-801 synthesized on a large scale at 77 K. The material exhibits a typical reversible type I N2 adsorption isotherm, with closed adsorption and desorption branches and no hysteresis, indicating its inherent microporosity characteristics.

[0025] 3. The low-crystallinity MOF-801 prepared in Comparative Example 1 was characterized. (1) Powder X-ray diffraction characterization Powder X-ray diffraction (PXRD) analysis was performed on the zirconium-based metal-organic framework material synthesized in Comparative Example 1, and the results were compared with those of a highly crystalline zirconium-based metal-organic framework material. Figure 20 As shown, the peak positions of the sample prepared in Example 1 are highly consistent with those of the simulated spectrum below, confirming that it is a pure phase with a complete crystal structure. Although the main peak of the sample prepared in Comparative Example 1 still corresponds to MOF-801, the peak shape is broadened and the intensity is reduced, indicating that the crystallinity is relatively low.

[0026] (2) Scanning electron microscope (SEM) Figure 21 The image shows a scanning electron microscope (SEM) image of MOF-801 prepared in Comparative Example 1. As can be seen from the image, the low-crystallinity MOF-801 exhibits nanoparticle aggregation. This confirms that the material lacks a long-range ordered crystal structure and belongs to a typical amorphous or low-crystallinity porous material.

[0027] (3) Nitrogen adsorption A certain amount of dried sample was weighed and placed in a test tube for vacuum degassing. After degassing, nitrogen adsorption at 77 K was tested. The adsorption performance was compared with that of highly crystalline zirconium-based metal-organic framework materials. The results are shown in [Figure number missing]. Figure 22 As shown in the figure, the highly crystallinity MOF-801 has the highest specific surface area (950 m²). 2 / g), while low-crystallinity MOF-801 exhibits a lower specific surface area (612m²) due to its lower crystallinity. 2 ( / g), while its irregular crystal surface also leads to excessive N2 condensation, forming a hysteresis loop.

[0028] Figure 23 A comparison of the pore size distributions of low-crystallinity and high-crystallinity MOF-801 shows that both types of MOF-801 possess micropores in the 6-8 Å range. Low-crystallinity MOF-801 exhibits additional pore distribution at 12-13 Å, which stems from its lower crystallinity, while high-crystallinity MOF-801, due to its uniform pore structure, does not show such pores. Example 3 describes the adsorption and separation tests of zirconium-based metal-organic framework materials on binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures. High-crystallinity ND-MOF-801 and low-crystallinity MOF-801 were placed in a test tube for vacuum degassing. After degassing, adsorption tests were performed on CF4, C2F6, C3F6 and C3F8 at 298K.

[0029] Figure 4 and Figure 5 The adsorption isotherms of highly crystalline MOF-801 for CF4, C2F6, C3F6, and C3F8 at 298 K are shown. At 298 K and 1 bar, the adsorption capacities of C3F6 and C3F8 are 62.4 cm⁻¹, respectively. 3 / g and 0.26cm 3 / g, adsorption ratio 240. The adsorption capacities of CF4 and C2F6 are 23.3 cm⁻¹, respectively. 3 / g and 48.2cm 3 / g.

[0030] Figure 24 This is a comparison of single-component adsorption isotherms of low-crystallinity and high-crystallinity MOF-801 for C3F6 and C3F8 at 298 K. It shows the adsorption isotherms of low-crystallinity MOF-801 for C3F6 (55.0 cm⁻¹) at 298 K and 1 bar. 3 / g) and C3F8 (38.1cm) 3 Both C3F6 and C4F6 exhibit significant co-adsorption. This significant co-adsorption behavior is caused by the broadened pore size distribution resulting from low crystallinity. In contrast, the highly crystallinity MOF-801 exhibits ideal sieving performance: its C3F6 adsorption capacity (62.4 cm³ / g) at 298 K and 1 bar is [missing value]. 3 The adsorption capacity ( / g) is not only higher than that of low-crystallinity MOF-801, but also has an extremely low adsorption capacity for C3F8 (0.26 cm⁻¹ at 1 bar). 3Its uniform pore structure achieves ideal size exclusion for C3F8 while maintaining high porosity.

[0031] The comparison shows that when the amount of formic acid regulator is low, the coordination competition between the regulator and the fumaric acid ligand is insufficient, leading to rapid nucleation and the formation of low-crystallinity MOF-801 with a relatively wide pore structure distribution, resulting in severe co-adsorption. Conversely, increasing the amount of formic acid regulator effectively enhances the coordination competition between the regulator and the ligand, thereby forming highly crystalline MOF-801. Its uniform pore structure can achieve ideal size exclusion of C3F8 while maintaining high porosity.

[0032] To verify the actual separation performance of the highly crystallinity ND-MOF-801 on binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures, dynamic breakthrough experiments were conducted on C3F6 / C3F8 (1 / 9, v / v) mixtures and CF4 / C2F6 / C3F8 (1 / 1 / 1, v / v / v) mixtures, respectively. The results are as follows... Figure 6 As shown. When the C3F6 / C3F8 mixture passed through a column packed with ND-MOF-801, C3F8 appeared immediately at the outlet, while C3F6 remained in the column for 75 min. When the CF4 / C2F6 / C3F8 mixture passed through a column packed with ND-MOF-801, C3F8 also appeared immediately at the outlet, while C2F6 and CF4 remained in the column for 67 min and 27 min, respectively. Figure 7 ).

[0033] The stability and reusability of adsorbents are of great significance in practical industrial applications. ND-MOF-801 was immersed in NaOH and HCl solutions of different pH values ​​for 72 hours, respectively. Figure 8 As shown, the XRD patterns of ND-MOF-801 after soaking at different pH levels were consistent with the original XRD patterns, demonstrating that ND-MOF-801 has high acid and alkali stability. Furthermore, ND-MOF-801 was soaked in deionized water for 30 days, and... Figure 9 As shown, the XRD pattern of ND-MOF-801 after soaking in deionized water is consistent with the original XRD pattern, proving that ND-MOF-801 has extremely high water stability. Simultaneously, five C3F6 adsorption cycles were performed on ND-MOF-801. Figure 10 As shown, after the cyclic test, the adsorption capacity of C3F6 remained essentially unchanged, demonstrating good regeneration capability. To prove the recyclability of ND-MOF-801 in the C3F6 / C3F8 breakthrough experiment, the C3F6 / C3F8 breakthrough experiment was conducted five times consecutively. After each test, ND-MOF-801 was regenerated by vacuum desorption for 2 hours before the next test. Figure 11 As shown, the retention times of C3F6 in the adsorption layer of ND-MOF-801 adsorbent are almost identical. This indicates that ND-MOF-801 has good cycling performance and regeneration capability.

[0034] Example 4: Adsorption and separation tests of large-scale prepared zirconium-based metal-organic framework materials on binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures. A certain amount of zirconium-based metal-organic framework material prepared on a large scale was placed in a test tube for vacuum degassing. After degassing, adsorption tests were performed on CF4, C2F6, C3F6 and C3F8 at 298K.

[0035] Figure 15 and Figure 16 The adsorption isotherms of ND-MOF-801 prepared on a large scale for CF4, C2F6, C3F6 and C3F8 at 298 K are shown. 4、 The adsorption capacities of C2F6, C3F6, and C3F8 did not decrease. Excellent sieving performance was maintained for binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures.

[0036] To verify the actual separation performance of the large-scale prepared ND-MOF-801 for binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures, dynamic breakthrough experiments were conducted for the first time using a 100 mL large breakthrough column to separate C3F6 / C3F8 (1 / 9, v / v) mixtures and CF4 / C2F6 / C3F8 (1 / 1 / 1, v / v / v) mixtures. Figure 17 The result is as follows: Figure 18 As shown. When the C3F6 / C3F8 mixture passed through a column packed with large-scale prepared ND-MOF-801, C3F8 was detected instantaneously at the column outlet, while C3F6 remained in the column for approximately 1418 min before exiting. When the CF4 / C2F6 / C3F8 mixture passed through a column packed with large-scale prepared ND-MOF-801, C3F8 also appeared at the outlet very quickly, while C2F6 and CF4 remained in the column for 563 min and 186 min, respectively. Figure 19 Further, it was demonstrated that the large-scale prepared ND-MOF-801 can achieve one-step separation of C3F8 in binary C3F6 / C3F8 mixtures and ternary CF4 / C2F6 / C3F8 mixtures, and obtain high-purity C3F8 (>99.999%).

Claims

1. An application of a highly crystallinity MOF-801 in the separation of C3F8, characterized in that: The highly crystallinity MOF-801 has a uniform microporous structure with a pore size distribution of 6-8 Å.

2. The application of the high crystallinity MOF-801 according to claim 1 in the separation of C3F8, characterized in that: The highly crystallinity MOF-801 can achieve efficient sieving and separation of binary C3F6 / C3F8 mixtures.

3. The application of the high crystallinity MOF-801 according to claim 1 in the separation of C3F8, characterized in that: The highly crystallinity MOF-801 can achieve one-step high-purity sieve separation of C3F8 in a ternary CF4 / C2F6 / C3F8 mixture.

4. A method for preparing the highly crystallinity MOF-801 as described in claim 1, characterized in that: Includes the following steps: Zirconium oxychloride octahydrate and fumaric acid were dissolved in N,N-dimethylformamide (DMF) solvent. The solid was sonicated to completely dissolve the solid. Anhydrous formic acid was added, and the mixture was stirred and mixed evenly. The mixture was then reacted in a hydrothermal reactor at 120°C for 24 hours. After filtration, the solid product was washed alternately with DMF and methanol and dried under vacuum to obtain the highly crystalline MOF-801.

5. The method for preparing highly crystallinity MOF-801 according to claim 4, characterized in that: The molar ratio of fumaric acid to zirconium oxychloride octahydrate was 1:1, the addition ratio of anhydrous formic acid to fumaric acid was 2.64 mL:0.7 mmol, and the volume ratio of anhydrous formic acid to DMF was 1.32:

9.

6. A method for large-scale preparation of the highly crystallinity MOF-801 as described in claim 1, characterized in that: Includes the following steps: Fumaric acid and zirconium oxychloride octahydrate were dissolved in DMF solvent, and the solid was completely dissolved by ultrasonic treatment. Anhydrous formic acid was added, and the mixture was refluxed at 120°C and atmospheric pressure for 24 hours. After filtration, the solid product was washed alternately with DMF and methanol, and then dried under vacuum to obtain high crystallinity MOF-801.

7. The method for large-scale preparation of highly crystallinity MOF-801 according to claim 6, characterized in that: The molar ratio of fumaric acid to zirconium oxychloride octahydrate was 1:1; the volume ratio of anhydrous formic acid to DMF was 0.16:1.08; and the addition ratio of anhydrous formic acid to fumaric acid was 0.08 L:21 mmol.

8. The application of the high crystallinity MOF-801 according to claim 1 in the separation of C3F8, characterized in that: The highly crystallinity MOF-801 can be recycled during gas separation.

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