Cobalt metal organic framework material for separating hexafluoropropylene / octafluoropropane mixed gas as well as preparation method and application of cobalt metal organic framework material

Abstract

The invention provides a cobalt metal organic framework material for separating hexafluoropropylene / octafluoropropane mixed gas as well as a preparation method and application thereof. The chemical formula of the cobalt metal organic framework material is [Co3 (OH) (C6H3O2NCl) 5 (H2O)], the cobalt metal organic framework material belongs to a monoclinic system, the space group is P21 / c, and the unit cell parameters are as follows: # imgabs0 # alpha = 90 degrees, beta = 92.7-92.8 degrees, gamma = 90 degrees and Z = 4; wherein OH represents a hydroxyl group; c6H3O2NCl represents 3-chloroisonicotinic acid without a hydrogen atom of a formic acid group; h2O is a water molecule. The preparation method comprises the following steps: placing cobalt nitrate hexahydrate, 3-chloroisonicotinic acid and an organic solvent in a glass bottle, adding fluoboric acid, and reacting at 363-383 K to obtain the cobalt metal organic framework material. The cobalt metal organic framework material can be used for separating hexafluoropropylene / octafluoropropane mixed gas, so that pure octafluoropropane gas is obtained.

Description

Technical Field

[0001] The invention belongs to the field of coordination chemistry, and in particular relates to a cobalt metal organic framework material for separating hexafluoropropylene / octafluoropropane mixed gas, a preparation method and an application thereof. Background Art

[0002] Octafluoropropane plays an important role in the electronic semiconductor industry and the integrated circuit manufacturing industry. Its good chemical stability, thermal stability and effective etching function make it widely used in the production process of ultra-large-scale integrated circuits, solar cells and other devices. At the same time, the purity requirements of octafluoropropane are very strict. The higher the purity of octafluoropropane, the better the product quality. However, the traditional method of producing octafluoropropane is to add fluorine to hexafluoropropylene to obtain a mixed gas with 1-10% residual hexafluoropropylene, which needs further purification to obtain the required high-purity octafluoropropane (purity greater than 99.9%). However, the separation of octafluoropropane and hexafluoropropylene is very challenging because their physical properties and molecular sizes are very similar. The mixture needs to be distilled multiple times under strict conditions to separate. This technology requires large distillation tower equipment and low temperature and high pressure conditions, high energy consumption, and huge equipment investment costs. Therefore, there is an urgent need to develop low-cost, low-energy consumption and efficient separation technology. Physical adsorption gas separation technology based on porous materials is considered to be a promising alternative technology because this separation technology has the advantages of simple implementation, environmental friendliness and low investment cost. Summary of the invention

[0003] Metal-organic framework materials are a new type of crystalline porous material with advantages such as abundant open metal sites, easily modified framework structure and pore environment, which makes them have broad application prospects in the field of gas storage or separation. Therefore, the separation of hexafluoropropylene / octafluoropropane mixed gas can be achieved by rationally designing the pore structure and pore environment of the metal-organic framework, thereby obtaining pure octafluoropropane gas. The object of the present invention is to provide a cobalt metal-organic framework material and a preparation method thereof, which can be used as a functional material for separating hexafluoropropylene / octafluoropropane mixed gas to obtain pure octafluoropropane gas.

[0004] In the first aspect, the present invention provides a cobalt metal organic framework material, whose chemical formula is [Co3(OH)(C6H3O2NCl)5(H2O)], belongs to the monoclinic system, has a space group of P21 / c, and a unit cell parameter of α=90°,β=92.7°~92.8°,γ=90°,Z=4; wherein OH represents hydroxyl group; C6H3O2NCl represents 3-chloroisonicotinic acid from which the hydrogen atom of the formic acid group is removed; and H2O represents a water molecule.

[0005] In a second aspect, the present invention provides a method for preparing a cobalt metal organic framework material, which comprises the following steps:

[0006] Cobalt nitrate hexahydrate, 3-chloroisonicotinic acid and an organic solvent are placed in a glass bottle, and fluoroboric acid is added, and then reacted at 363-383K to obtain the cobalt metal organic framework material.

[0007] Further, the molar ratio of the cobalt nitrate hexahydrate to 3-chloroisonicotinic acid is (1-3):(3-5). Preferably, the molar ratio of the cobalt nitrate hexahydrate to 3-chloroisonicotinic acid is 1:2.

[0008] Furthermore, the organic solvent is N,N-dimethylacetamide solution and methanol solution.

[0009] Furthermore, the molar ratio of the cobalt nitrate hexahydrate, N,N-dimethylacetamide and methanol is 1:(500-800):(600-800).

[0010] Furthermore, the volume ratio of the fluoroboric acid, N,N-dimethylacetamide and methanol is 1:(16-29):(8-12).

[0011] Furthermore, the reaction time is 45-48 hours.

[0012] In a third aspect, the present invention provides an application of a cobalt metal organic framework material, wherein the cobalt metal organic framework material can be used as a functional material for separating a hexafluoropropylene / octafluoropropane mixed gas to obtain pure octafluoropropane gas.

[0013] The organic ligand 3-chloroisonicotinic acid has a highly conjugated pyridine ring, oxygen atoms and nitrogen atoms with strong coordination ability, and the stable structure of the trinuclear cobalt cluster can construct a cobalt metal organic framework material with novel structure and special functions. At the same time, the suitable pore structure and pore environment make the hexafluoropropylene and the framework structure have a stronger interaction, which is conducive to the preferential adsorption of hexafluoropropylene, and then realizes the purification of octafluoropropane gas from the hexafluoropropylene / octafluoropropane mixture.

[0014] Beneficial effects of the present invention:

[0015] (1) A cobalt metal organic framework material is provided, which has mild synthesis conditions, simple operation, low energy consumption, easy realization, low requirements for reaction and purity, and meets the requirements of "green chemistry";

[0016] (2) The cobalt metal organic framework material can be used to separate hexafluoropropylene / octafluoropropane mixed gas with good separation performance. The separation coefficient for the hexafluoropropylene / octafluoropropane mixed gas (volume ratio of 10:90) is 15.7 to 91.1. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The molecular structure diagram of the cobalt metal organic framework of the present invention.

[0018] Figure 2 The three-dimensional structure diagram of the cobalt metal organic framework of the present invention.

[0019] Figure 3 It is a separation curve diagram of the hexafluoropropylene / octafluoropropane mixed gas of the cobalt metal organic framework of the present invention (in the hexafluoropropylene / octafluoropropane mixed gas, the volume ratio of hexafluoropropylene / octafluoropropane is 10:90). DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The cobalt metal organic framework [Co3(OH)(C6H3O2NCl)5(H2O)] of the present invention can be obtained by conventional solvothermal method, and the specific reaction formula is:

[0022] 5C6H4O2NCl+3Co(NO3)2+2H2O→[Co3(OH)(C6H3O2NCl)5(H2O)]+6HNO3

[0023] C6H4O2NCl is the molecular formula of 3-chloroisonicotinic acid, and C6H3O2NCl is 3-chloroisonicotinic acid with the hydrogen atom of the formic acid group removed.

[0024] The present invention is further described below in conjunction with specific embodiments and drawings.

[0025] Embodiment 1:

[0026] Cobalt nitrate hexahydrate and 3-chloroisonicotinic acid were mixed in a molar ratio of 1:2 and placed in a 20-ml glass bottle containing 1 ml (10.8 mmol) of N,N-dimethylacetamide and 0.5 ml (12.5 mmol) of a methanol mixed solvent, and then 60 microliters (40% concentration) of a fluoroboric acid solution was added, wherein the amount of cobalt nitrate hexahydrate was controlled to be about 5 mg (0.017 mmol), and then reacted at a constant temperature of 373 K for 46 hours to obtain a pink polyhedral crystal of a cobalt metal organic framework material [Co3(OH)(C6H3O2NCl)5(H2O)] (where OH represents a hydroxyl group; C6H3O2NCl represents 3-chloroisonicotinic acid from which the hydrogen atom of the formic acid group has been removed; and H2O represents a water molecule).

[0027] Embodiment 2:

[0028] Cobalt nitrate hexahydrate and 3-chloroisonicotinic acid were mixed in a molar ratio of 2:3 and placed in a 20-ml glass bottle containing 2 ml (21.6 mmol) of N,N-dimethylacetamide and 0.8 ml (20 mmol) of a methanol mixed solvent, and then 70 μl (40%) of a fluoroboric acid solution was added, wherein the amount of cobalt nitrate hexahydrate was controlled to be about 8 mg (0.027 mmol). The mixture was then reacted at a constant temperature of 383 K for 47 hours to obtain a pink polyhedral crystal of a cobalt metal organic framework material [Co3(OH)(C6H3O2NCl)5(H2O)] (where OH represents a hydroxyl group; C6H3O2NCl represents 3-chloroisonicotinic acid from which the hydrogen atom of the formic acid group has been removed; and H2O represents a water molecule).

[0029] Embodiment 3:

[0030] Cobalt nitrate hexahydrate and 3-chloroisonicotinic acid are mixed in a molar ratio of 3:5 and placed in a 20-ml glass bottle containing 2 ml (21.6 mmol) of N,N-dimethylacetamide and 1 ml (25 mmol) of a methanol mixed solvent, and then 90 microliters (40% concentration) of a fluoroboric acid solution is added, wherein the amount of cobalt nitrate hexahydrate is controlled to be about 12 mg (0.04 mmol), and then reacted at a constant temperature of 366 K for 48 hours to obtain a pink polyhedral crystal of a cobalt metal organic framework material [Co3(OH)(C6H3O2NCl)5(H2O)] (where OH represents a hydroxyl group; C6H3O2NCl represents 3-chloroisonicotinic acid from which the hydrogen atom of the formic acid group is removed; and H2O represents a water molecule).

[0031] The pink polyhedral crystals obtained in Example 1 were tested. Single crystal X-ray diffractometer tests showed that the pink polyhedral crystals were the target compound, i.e., cobalt metal organic framework materials. X-ray single crystal diffraction data were collected on a Bruker D8 Venture single crystal diffractometer. The CuKα copper target (wavelength of 1.54178 angstroms) was used to collect diffraction data in ω scanning mode. All non-hydrogen coordinates were obtained using the direct method and full matrix least squares method using the SHELXL-2018 program. The "crystallographic parameters" of the compound are shown in Table 1, and the molecular structure diagram is shown in Table 1. Figure 1 , please see the three-dimensional structure diagram Figure 2 .

[0032] Table 1. Crystallographic parameters and structural analysis of cobalt metal organic framework material [Co3(OH)(C6H3O2NCl)5(H2O)]

[0033]

[0034]

[0035] Note: R1=∑||F o |-|F c || / ∑|F o |,wR2=[∑w(F o 2 -F c 2 ) 2 / ∑w(F o 2 ) 2 ] 0.5 .

[0036] The cobalt metal organic framework material in the above embodiment is a pink polyhedral crystal, the structure of which comprises a trinuclear cluster [Co3(OH)] unit formed by one OH bridging three cobalt ions, each [Co3(OH)] structural unit being bridged with nine 3-chloroisonicotinic acid ligands to form a three-dimensional structure ( Figure 2 ), therefore, it is a three-dimensional metal-organic framework material.

[0037] As shown in Table 1, the crystal structure parameters of the present invention are: the chemical formula is [Co3(OH)(C6H3O2NCl)5(H2O)], (OH represents a hydroxyl group; C6H3O2NCl represents 3-chloroisonicotinic acid from which the hydrogen atom of the formic acid group is removed; H2O represents a water molecule), belongs to the monoclinic system, has a space group of P21 / c, and has a unit cell parameter of α=90°,β=92.7°~92.8°,γ=90°,Z=4. The cobalt metal organic framework material can effectively separate the hexafluoropropylene / octafluoropropane mixed gas to obtain pure octafluoropropane gas.

[0038] The separation coefficient of the cobalt metal organic framework material for the hexafluoropropylene / octafluoropropane mixed gas (volume ratio of 10:90) is 15.7-91.1, indicating that the cobalt metal organic framework material can be used as a material for separating the hexafluoropropylene / octafluoropropane mixed gas. Under 298K, a breakthrough experiment was conducted by introducing a hexafluoropropylene / octafluoropropane mixed gas with a gas flow rate of 4 ml / min. At 12.7 minutes / gram (in units of "penetration time / sample mass"), octafluoropropane first penetrated from the adsorption column, while the hexafluoropropylene component was not detected at the outlet of the adsorption column until 67.2 minutes / gram, indicating that when the mixed gas flows through the adsorption column, the hexafluoropropylene in the mixed gas is preferentially adsorbed in the adsorption column, so that high-purity octafluoropropane (99.999%) can be directly obtained at the tail of the adsorption column, indicating that the cobalt metal organic framework material can effectively separate the hexafluoropropylene / octafluoropropane mixed gas, and then obtain pure octafluoropropane gas.

[0039] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The protection scope of the present invention should be defined by the claims.

Claims

1. A cobalt metal organic framework material, characterized in that: The chemical formula is [Co3(OH)(C6H3O2NCl)5(H2O)], it belongs to the monoclinic system, the space group is P21 / c, and the unit cell parameters are α=90°, β=92.7°~92.8°, γ=90°, Z=4; wherein OH represents a hydroxyl group; C6H3O2NCl represents 3-chloroisonicotinic acid from which the hydrogen atom of the formic acid group is removed; and H2O represents a water molecule.

2. A method for preparing the cobalt metal organic framework material as claimed in claim 1, comprising the following steps: Cobalt nitrate hexahydrate, 3-chloroisonicotinic acid and an organic solvent are placed in a glass bottle, and fluoroboric acid is added, and then reacted at 363-383K to obtain the cobalt metal organic framework material.

3. The method according to claim 2, characterized in that The organic solvent is N,N-dimethylacetamide solution and methanol solution.

4. The method according to claim 2, characterized in that: The molar ratio of the cobalt nitrate hexahydrate to 3-chloroisonicotinic acid is (1-3):(3-5).

5. The method according to claim 4, characterized in that The molar ratio of the cobalt nitrate hexahydrate to 3-chloroisonicotinic acid is 1:

2.

6. The method according to claim 3, characterized in that The molar ratio of the cobalt nitrate hexahydrate, N,N-dimethylacetamide and methanol is 1:(500-800):(600-800).

7. The method according to claim 3, characterized in that The volume ratio of the fluoroboric acid, N,N-dimethylacetamide and methanol is 1:(16-29):(8-12).

8. The method according to claim 2, characterized in that: The reaction time is 45-48 hours.

9. Use of the cobalt metal organic framework material according to claim 1 in the field of mixed gas separation.

10. The use according to claim 8, characterized in that: The cobalt metal organic framework material is used for separating the hexafluoropropylene / octafluoropropane mixed gas to obtain pure octafluoropropane gas.

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