Woven frame material, preparation method thereof and application of woven frame material in dynamic separation of water and heavy water at room temperature

Abstract

The invention discloses a woven frame material, a preparation method thereof and application of the woven frame material to dynamic separation of water and heavy water at room temperature. The braided framework material can be obtained by reacting tetrahedral borate obtained by reacting tetra (4-boric acid phenyl) methane with catechol with 1, 2-trans-bis (4-pyridyl) ethylene. The woven frame material disclosed by the invention can be used for dynamically separating any two or three of H2O, HDO and D2O at room temperature. The problems of high energy consumption, low efficiency and the like in the traditional separation process can be solved.

Description

Technical Field

[0001] The present invention relates to the field of materials science, and in particular to a pure organic braided framework material, a preparation method thereof, and an application thereof in dynamically separating water and heavy water at room temperature. Background Art

[0002] Heavy water (D2O) is a strategically important resource with a wide range of applications, from basic scientific research to military safety and the operation of large nuclear reactors. Furthermore, heavy water is the primary source of deuterium for many critical deuterated reagents. Therefore, obtaining high-purity heavy water from natural sources is crucial. However, due to the extremely low natural concentration of heavy water, approximately 0.015%, and more importantly, because heavy water and ordinary water have very similar physicochemical properties and the same kinetic size, water isotopes are widely considered to be among the most difficult to separate.

[0003] Currently, traditional separation methods based on the subtle kinetic and thermodynamic differences between water and heavy water, such as distillation, electrolysis, and proton exchange, are not only energy-intensive but also inefficient. Therefore, developing clean and efficient methods for water isotope separation has been a long-standing goal in the field. Using porous materials to separate water and heavy water to produce heavy water is one of the most promising approaches.

[0004] Porous materials, with their tunable nanoscale confinement, offer new avenues for developing non-thermodynamically driven separation technologies. In recent years, carbon materials, metal-organic frameworks, and covalent organic frameworks have shown promising results in this area. However, because water isotopologues (H2O / HDO / D2O) have highly similar kinetic diameters and physicochemical properties, traditional separation mechanisms based on size sieving or chemical adsorption often have limited success.

[0005] A paper (Yan Su. Nature 2022, 611, 289-294) discloses a method for static separation of water isotope mixtures using the conformational flexibility of metal-organic frameworks. Although static adsorption separation has achieved important breakthroughs, dynamic separation technology, which is more industrially valuable—that is, a process that achieves continuous separation under pressure—still faces major technical bottlenecks (Nature 2022, 611, 243-244; Nat. Mater. 2023, 22, 406-406). This scalable separation mode has been repeatedly emphasized in recent years for its strategic significance due to its engineering advantages. Summary of the Invention

[0006] The invention provides a braided frame material, a preparation method and an application thereof.

[0007] The specific technical solutions are as follows:

[0008] In a first aspect, the present invention provides a braided frame material having a structure shown in Formula 2:

[0009]

[0010] The braided frame material described in the first aspect can be prepared by the preparation method described in the second aspect.

[0011] In a second aspect, the present invention provides a method for preparing a braided frame material, comprising: reacting a tetrahedral borate ester having a structure shown in Formula 1 with 1,2-trans-bis(4-pyridyl)ethylene to obtain a braided frame material having

[0012] Braided frame material with the structure shown in Formula 2;

[0013]

[0014] In the method for preparing the braided framework material described in the second aspect, the temperature for the reaction of tetrahedral borate with 1,2-trans-bis(4-pyridyl)ethylene can be 40-60°C, for example, 50°C.

[0015] In the method for preparing the braided framework material of the second aspect, preferably, tetrahedral borate and 1,2-trans-bis(4-pyridyl)ethylene are reacted in a solution. Furthermore, the solvent in the solution may include benzene.

[0016] The second aspect of the method for preparing the braided framework material further includes: vacuum heating and activating the reaction product of tetrahedral borate and 1,2-trans-bis(4-pyridyl)ethylene to obtain the braided framework material. Furthermore, the vacuum heating and activation temperature can be 105-115°C, such as 110°C, and the vacuum heating and activation time can be 3-4 hours.

[0017] The preparation method of the braided frame material described in the second aspect, the tetrahedral borate can be prepared by the preparation method described in the fifth aspect.

[0018] In a third aspect, the present invention provides use of the braided framework material described in the first aspect or the braided framework material prepared by the preparation method described in the second aspect for separating any two or three of H2O, HDO, and D2O. The braided framework material can be used to separate any two or three of H2O, HDO, and D2O at room temperature (e.g., 25°C).

[0019] As a general inventive concept, in a fourth aspect, the present invention provides a tetrahedral borate ester having a structure shown in Formula 1:

[0020]

[0021] In a fifth aspect, the present invention provides a method for preparing the tetrahedral borate described in the fourth aspect, comprising: under the protection of an inert atmosphere, heating tetrakis(4-boronic acid phenyl)methane and catechol in a solution to react, removing water during the reaction, and removing the solvent after the reaction to obtain the tetrahedral borate.

[0022] In the present invention, the inert atmosphere refers to a gas atmosphere that does not participate in the reaction, such as a nitrogen atmosphere.

[0023] Preferably, in the method for preparing tetrahedral borate, the molar ratio of tetrakis(4-boronic acid phenyl)methane to catechol is 1:4 to 4.5.

[0024] In the method for preparing tetrahedral borate, the solvent in the solution may include at least one of toluene and methanol. Furthermore, the solvent in the solution may include toluene and methanol. Furthermore, the volume ratio of toluene to methanol in the solvent in the solution may be 100:0.5-5.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The braided framework material of the present invention can dynamically separate any two or three of H2O, HDO, and D2O at room temperature.

[0027] The present invention can solve the problems of high energy consumption and low efficiency in traditional separation processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the activation process of PWPN-1 crystals.

[0029] Figure 2 The performance test results of PWPN-1a are shown, among which: (A) is the CO2 adsorption isotherm of PWPN-1a at 195K; (B) is the H2O and D2O vapor adsorption curve of PWPN-1a at 298K and in the pressure range of 0-2.5kPa, with the equilibrium time for each data point being 600 seconds; (C) is the adsorption curve of H2O and D2O by PWPN-1a at 298K and relative pressure (P / Ps) = 0.9; (D) is the diffusion rate measurement result of H2O and D2O in PWPN-1a at 298K and P / Ps = 0.95.

[0030] Figure 3 These are the experimental breakthrough curves of PWPN-1a for D2O / H2O mixture at 298K and 1 bar, where: (A) corresponds to a D2O / H2O volume ratio of 80 / 20; (B) corresponds to a D2O / H2O volume ratio of 90 / 10.

[0031] Figure 4Schematic diagram of the room-temperature dynamic co-adsorption separation of water isotopologues by PWPN-1a. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0033] A method for preparing a woven framework material that can be used for dynamic separation of water and heavy water at room temperature adopts the following synthetic route:

[0034]

[0035] The specific preparation process includes the following steps:

[0036] (1) Tetrakis(4-boronic acid phenyl)methane and catechol were used as monomers. Tetrakis(4-boronic acid phenyl)methane and catechol were added to a mixed solution of toluene and methanol (volume ratio 100:0.5) in a molar ratio of 1:4. The mixture was heated to reflux under nitrogen atmosphere. Water produced during the reaction was removed using a water separator. After the reaction was completed, the solvent was dried to obtain the product tetrahedral borate ester 1.

[0037] (2) The tetrahedral borate ester 1 obtained in step (1) and 1,2-trans-bis(4-pyridyl)ethylene were dispersed in benzene, ultrasonicated in a water bath for 15 minutes, kept warm at 50°C for reaction, and slowly cooled to room temperature after the reaction was completed. The yellow product PWPN-1 shown in Formula 2 was obtained by filtration.

[0038] (3) The yellow product PWPN-1 was heated at 110°C under vacuum for 3 hours to obtain the activated product PWPN-1a.

[0039] The products PWPN-1 and PWPN-1a were analyzed by single crystal diffraction. Their structures are shown in Figure 2. Figure 1 shown. Figure 1 The process of activation of PWPN-1 crystals to form PWPN-1a is also demonstrated.

[0040] Table 1 shows the single crystal structure data of PWPN-1 crystal.

[0041] Table 1

[0042]

[0043] Table 2 shows the single crystal structure data of PWPN-1a.

[0044] Table 2

[0045]

[0046] The adsorption performance of water and heavy water of the activated product PWPN-1a was tested using a gas adsorption instrument. Figure 2 The pore characteristics of PWPN-1a were characterized by CO2 gas adsorption test at 195K, and its specific surface area was calculated to be 235m based on the BET model. 2 g -1 ( Figure 2 A), confirming the formation of a porous woven network. Subsequently, the H2O / D2O vapor adsorption isotherm at 298K was measured in the pressure range of 0-2.5kPa. The results showed that the equilibrium adsorption capacity of the material for D2O was always higher than that for H2O( Figure 2 B) At 2.5 kPa, the adsorption capacities of D2O and H2O were 84.07 mL g -1 and 69.12 mL g -1 , indicating that PWPN-1a has the potential for H2O / D2O equilibrium adsorption separation at 298K. To further evaluate the adsorption kinetics, adsorption experiments at 298K were carried out under the condition of P / Ps = 0.9 ( Figure 2 C), at this temperature, both D2O and H2O reached adsorption equilibrium within 80 minutes, and the dynamic adsorption capacity of D2O (reached 329.94 mL g after 85 minutes) -1 ) was significantly higher than H2O (271.11 mL g -1 ). Through the micropore diffusion model fitting, it was found that the adsorption rates of H2O and D2O were 4.4×10 6 s -1 and 5.2×10 6 s -1 , kinetic selectivity reached 1.2( Figure 2 D), confirming the potential of the material for dynamic H2O / D2O separation.

[0047] The separation performance of the material PWPN-1a water and heavy water was studied using penetration equipment, such as Figure 3 As shown. A dynamic penetration experiment was conducted using a small test bed simulating an industrial process. Using nitrogen as the carrier gas, a total volume of 100 mL of a D2O / H2O mixture with a D2O / H2O volume ratio of 80 / 20 was bubbled through the column at a temperature of 298 K, a column pressure of 1 bar, and a nitrogen flow rate of 5.0 mL min -1 Under the condition of , the mixed steam was passed through the adsorption column filled with PWPN-1a (250mg). The results after correction of mass spectrometry detection signal showed that ( Figure 3 A), H2O(280min g -1 ) and D2O(410min g -1) had significant differences in their penetration retention times, and it was unexpectedly discovered that the hydrogen-deuterium exchange product HDO could also be distinguished. Following the above experimental penetration test process, only the D2O / H2O volume ratio in the mixed solution was increased to 90 / 10, and the D2O penetration retention time was extended to 597.09 min g -1 , with H2O(415.00min g -1 ) is more obvious ( Figure 3 B). Figure 4 Schematic diagram showing the room-temperature dynamic co-adsorption separation of water isotopologues by PWPN-1a.

[0048] like Figure 3 As shown, water and heavy water will undergo partial hydrogen-deuterium exchange when penetrating PWPN-1a. One of the advantages of the braided framework material of the present invention is that the semi-deuterated water produced by the hydrogen-deuterium exchange can also be separated from water and heavy water.

[0049] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A braided frame material, characterized in that: It has the structure shown in formula 2:

2. A method for preparing a braided frame material, characterized in that: include: A tetrahedral borate ester having a structure shown in Formula 1 reacts with 1,2-trans-bis(4-pyridyl)ethylene to obtain a braided framework material having a structure shown in Formula 2; 3. The method for preparing a braided frame material according to claim 2, wherein: The temperature for the reaction of tetrahedral borate and 1,2-trans-bis(4-pyridyl)ethylene is 40-60°C.

4. The method for preparing a braided frame material according to claim 2, wherein: The tetrahedral borate ester is reacted with 1,2-trans-bis(4-pyridyl)ethylene in a solution in which the solvent includes benzene.

5. The method for preparing a braided frame material according to claim 2, wherein: The preparation method of the braided frame material further comprises: vacuum heating and activating the reaction product of tetrahedral borate and 1,2-trans-bis(4-pyridyl)ethylene to obtain the braided frame material.

6. The method for preparing a braided frame material according to claim 5, characterized in that: The temperature of the vacuum heating activation is 105-115°C; The time for the vacuum heating activation is 3 to 4 hours.

7. Use of the braided framework material according to claim 1 or the braided framework material prepared according to the preparation method according to any one of claims 2 to 6 for separating any two or three of H2O, HDO, and D2O.

8. A tetrahedral borate, characterized in that It has the structure shown in formula 1:

9. The method for preparing tetrahedral borate according to claim 8, wherein: include: Under the protection of an inert atmosphere, tetrakis(4-boronic acid phenyl)methane and catechol are heated and reacted in a solution, water is removed during the reaction, and the solvent is removed after the reaction is completed to obtain the tetrahedral borate ester.

10. The method for preparing tetrahedral borate according to claim 9, characterized in that: The molar ratio of tetrakis(4-boronic acid phenyl)methane to catechol is 1:4 to 4.5; The solvent in the solution includes at least one of toluene and methanol.

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