A multi-functional bimetallic organic framework material based on imidazole carboxylic acid, preparation method and application

Abstract

The present invention discloses a multifunctional bimetallic organic framework material of imidazole carboxylic acid, a preparation method and an application. The chemical formula of the multifunctional bimetallic organic framework material of imidazole carboxylic acid is K<subgt;2< / subgt;Pb<subgt;2< / subgt>(imda)<subgt;2< / subgt>·4H<subgt;2< / subgt>O. K<subgt;2< / subgt>Pb<subgt;2< / subgt>(imda)<subgt;2< / subgt>·4H<subgt;2< / subgt>O in the present invention has good stability, and at the same time contains K<supgt;+< / supgt> and Pb<supgt;2+ ions, which have flame extinction and catalytic effects; and its preparation method is simple, with less energy consumption, short synthesis time, high efficiency, and can realize large-scale industrial production.

Description

Technical Field

[0001] The present invention relates to the field of solid propellants, and particularly to an imidazole carboxylic acid-based multifunctional bimetallic organic framework material, a preparation method and an application thereof. Background Art

[0002] A solid propellant is a composite material containing an oxidizer and a high-energy fuel, with the characteristics of high energy and high density. It can continuously burn without the presence of an external oxidizer, providing a large amount of power, and is widely used in fields such as strategic missiles, tactical missiles, rockets, and space launch vehicles. The gas products generated by the combustion of solid propellants mainly include CO2, H2O, CO, H2, and N2. Among them, the contents of CO and H2 are more than half of the gas molar fraction value. The gas containing a large amount of CO and H2 is prone to re-combustion with oxygen in the atmosphere to generate carbon dioxide and water, accompanied by a large amount of heat release, resulting in an increase in flame temperature and the generation of bright visible light radiation, strong infrared and ultraviolet light radiation. This phenomenon is called afterburning. The bright flame formed by afterburning is easily detected by the enemy's detectors, reducing the survival ability of the weapon system and the penetration efficiency of the missile. Moreover, the high-temperature, high-speed plasma non-uniform flow field formed by the flame will also attenuate the intensity of missile guidance signals such as infrared rays, lasers, and electromagnetic waves passing through it, resulting in a decrease in the missile hitting accuracy; for normal airborne, the strong bright visible light generated by afterburning is very likely to cause a short-term vision disorder for the pilot, affecting driving safety.

[0003] By adding a flame suppressant to the propellant, the afterburning can be effectively inhibited, which is of great significance for achieving low exhaust plume characteristic signals. Research shows that the main component that has a flame-suppressing effect on the secondary flame is potassium ion (K + ). The key to eliminating the flame lies in forming a high concentration of KOH to terminate the chain reaction. However, the currently used traditional potassium salt flame suppressants have the disadvantage of strong hygroscopicity and will affect the platform combustion rate, making it difficult to meet the development requirements of high-performance gun weapons. With the development of technology and military, at present, some MOFs have been used in the field of combustion catalysis, playing a role in suppressing afterburning and unstable combustion, meeting the requirements of solid propellants for high energy, high burning rate, low characteristic signals, etc.

[0004] Therefore, based on the structural characteristics of MOFs and their good stability, it is considered that MOFs have important research significance in new potassium salt flame suppressants. While meeting the flame suppression requirements, they can also improve the comprehensive combustion performance of propellants. In addition, by adjusting factors such as coordination mode, ligand composition, crystal structure, and microchannel morphology, the index parameters such as energy performance, thermal behavior, water stability, and safety performance of MOFs can be optimized. Based on the strong structural characteristics of MOFs and the good flame suppression effect of potassium salts, combining the two, there is an urgent need to prepare a new type of potassium salt bimetallic MOF to meet the requirements of solid propellants for high energy, high burning rate, low characteristic signal, etc. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that the current flame suppressant is easily soluble in water and will affect the combustion performance of the propellant, and provide a multifunctional bimetallic organic framework material of imidazole carboxylic acid, which has both flame suppression and catalytic effects, and is expected to be applied to solid propellants to regulate the combustion performance of the propellant and reduce the characteristic signal of the propellant.

[0006] The technical problems to be solved by the present invention are realized through the following technical solutions:

[0007] A multifunctional bimetallic organic framework material of imidazole carboxylic acid, and the chemical formula of the multifunctional bimetallic organic framework material of imidazole carboxylic acid is K2Pb2(imda)2·4H2O.

[0008] After the crystal structure of the multifunctional bimetallic organic framework material of imidazole carboxylic acid is tested, the test results are as follows:

[0009]

[0010]

[0011] A preparation method of a multifunctional bimetallic organic framework material of imidazole carboxylic acid, comprising the following steps:

[0012] (1) Weigh a certain proportion of H3imda and add a certain amount of distilled water to prepare a ligand solution;

[0013] (2) Then add a certain amount of KOH solution to the ligand solution in step (1), stir until a clear solution is obtained, prepare a mixture, and transfer the mixture into a hydrothermal reactor;

[0014] (3) Then add a certain amount of Pb(NO3)2 to the mixture in step (2), stir while adding, obtain a flocculent precipitate, install the hydrothermal reactor and put it into a programmable temperature-controlled oven;

[0015] (4) The hydrothermal reactor is heated from room temperature to 90 °C in an oven in 30 min, then kept at this temperature for 12 hours, and then cooled to room temperature at a rate of 5 °C / h. The oven is turned off and the reactor is taken out;

[0016] (5) The experimental samples are washed three times with water and ethanol respectively, and then dried in an oven at 60 °C for 12 h to obtain white spherical crystal particles.

[0017] The molar ratio of H3imda:Pb(NO3)2:KOH is 4:1:10.

[0018] The water in step (5) is distilled water.

[0019] The content of H3imda in step (1) is 32.18 mg, and the content of distilled water is 4 mL; the concentration of KOH solution in step (2) is 1 mol / L, and the addition amount is 0.5 mL; the concentration of Pb(NO3)2 solution in step (3) is 1 mol / L, and the addition amount is 50 μL.

[0020] The catalytic and flame extinction effects of the imidazole carboxylic acid-based multifunctional bimetallic organic framework material described in the present invention in propellants.

[0021] Advantages of the present invention:

[0022] 1. K2Pb2(imda)2·4H2O in the present invention has good stability, and at the same time contains K + , Pb 2+ ions, which have flame extinction and catalytic effects; and its preparation method is simple, with less energy consumption, short synthesis time, high efficiency, and can achieve large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of K2Pb2(imda)2·4H2O. The lines in the figure do not represent specific chemical bonds, but only represent the connection relationship between each structural unit; (a) the smallest asymmetric unit; (b) the coordination environment of K and Pb;

[0024] Figure 2 is the crystal structure diagram of K2Pb2(imda)2·4H2O in the a-axis and b-axis directions;

[0025] Figure 3 is the powder XRD pattern of K2Pb2(imda)2·4H2O;

[0026] Figure 4 is the FT-IR spectrum of K2Pb2(imda)2·4H2O;

[0027] Figure 5DTA curve of K2Pb2(imda)2·4H2O at a heating rate of 10 °C / min;

[0028] Figure 6 TG-DTG curve of K2Pb2(imda)2·4H2O at a heating rate of 10 °C / min;

[0029] Figure 7 Comparison curve of the catalytic effect of K2Pb2(imda)2·4H2O on ammonium perchlorate (AP) and pure AP at a heating rate of 10 °C / min. Specific embodiments

[0030] The present invention will be further described below in conjunction with specific embodiments and drawings. All chemical reagents used in this experiment are conventional reagents and can be obtained commercially.

[0031] As Figure 1 — Figure 7 shown, the present invention discloses a multifunctional bimetallic organic framework material of imidazole carboxylic acid; wherein, the chemical formula of the multifunctional bimetallic organic framework material of imidazole carboxylic acid is K2Pb2(imda)2·4H2O.

[0032] Specifically, the present invention uses 4,5-imidazole dicarboxylic acid (H3imda) as an organic ligand, and lead ions and potassium ions as metal centers, and prepares K2Pb2(imda)2·4H2O by heating.

[0033] Among them, the prepared K2Pb2(imda)2·4H2O belongs to the cubic crystal system, the space group is P21, and the density is 3.177 g / cm 3 , after the crystal structure test, the test results are as follows:

[0034]

[0035]

[0036] The present invention also discloses a preparation method of the multifunctional bimetallic organic framework material of imidazole carboxylic acid, that is, a synthesis method of K2Pb2(imda)2·4H2O, including the following steps:

[0037] (1) Weigh a certain proportion of 4,5-imidazole dicarboxylic acid (H3imda) and add a certain amount of distilled water to prepare a ligand solution;

[0038] (2) Then add a certain amount of potassium hydroxide (KOH) solution to the ligand solution in step (1), stir until a clear solution is obtained, prepare a mixture, and transfer the mixture into a hydrothermal autoclave;

[0039] (3) Then add a certain amount of lead nitrate solution (Pb(NO3)2) to the mixture in step (2), stirring while adding, to obtain a flocculent precipitate. After installing the hydrothermal reactor, place it in a programmable temperature-controlled oven.

[0040] (4) The hydrothermal reactor is heated from room temperature to 90 °C in the oven within 30 min, then kept at this temperature for 12 hours, and then cooled to room temperature at a rate of 5 °C / h. Turn off the oven and take out the reaction kettle.

[0041] (5) Wash the experimental samples three times with water and ethanol respectively, and then dry them in the oven at 60 °C for 12 h to obtain white spherical crystal particles.

[0042] Specific examples of the above preparation method are as follows:

[0043] First, weigh 32.18 mg of H3imda and add 4 mL of distilled water to obtain a prepared organic ligand solution.

[0044] Then accurately pipette 0.5 mL of KOH (1 mol / L) solution into the ligand, and then stir until the solution is clear to obtain a prepared mixture.

[0045] Then pipette 50 μL of Pb(NO3)2 (1 mol / L) and add it to the mixture of H3imda and KOH. Among them, the molar ratio of H3imda, KOH to Pb(NO3)2 is 4:10:1. During the addition process, stir while adding, and the solvent is only water to obtain a flocculent precipitate.

[0046] Then transfer the obtained flocculent precipitate to a 10 mL hydrothermal reactor, seal it and place it in a programmable temperature-controlled oven. Finally, wash it three times with distilled water and ethanol respectively, and then dry it in the oven at 60 °C for 10 h to obtain transparent K2Pb2(imda)2·4H2O crystal particles, and the yield is about 24.02%.

[0047] In the actual preparation of the present invention, the temperature of the hydrothermal reactor in the oven is less than 100 °C, which has the advantage of less energy consumption. At the same time, the oven insulation time is about 12 hours, and the synthesis time is short, which has the advantage of high efficiency.

[0048] In summary, the potassium-containing double-metal organic framework material of imidazole carboxylic acid in the present invention has good stability, and at the same time contains K + , Pb 2+ ions, which have flame extinction and catalytic effects; and its preparation method is simple and can achieve large-scale industrial production.

[0049] Schematic diagram of the single crystal structure of the obtained transparent K2Pb2(imda)2·4H2O crystal particles ( Figure 1 ), Figure 2Crystal structure diagrams in the directions of the a-axis and b-axis.

[0050] The structure and composition of K2Pb2(imda)2·4H2O crystals were characterized by using X-ray diffraction (XRD). With a Cu Kα source, the measurement angle range (2θ) was 5 - 50°, and the scanning rate was 8° / min. The XRD results of K2Pb2(imda)2·4H2O are as Figure 3 shown, and the results show that its experimental diffraction pattern is consistent with the XRD data calculated from the single crystal CIF file.

[0051] The FTIR spectral results of K2Pb2(imda)2·4H2O are as Figure 4 shown, where, at 1629.7 cm -1 spectrum

[0052] band corresponds to the vibration of the C–O bond in the carboxylic acid group of the ligand. The bands at 1443.2 cm -1 and 1346.2 cm -1 correspond to the vibrations of the C=N and C–N bonds on the pyrazine ring. The band at 989.7 cm -1 corresponds to the symmetric vibration of the Pb–N bond, and at 700–950 cm -1 correspond to the vibrations of the Pb–O and K–O bonds.

[0053] An experiment on K2Pb2(imda)2·4H2O was carried out using DTA with a heating rate of 10℃ / min and an air atmosphere, and the DTA curve as shown in Figure 5 was obtained. 126.2℃ is an endothermic peak, indicating the presence of water. The curve shows that there are three stages of decomposition, and the decomposition peak temperatures are 354.1℃, 423.4℃, and 467.2℃ respectively.

[0054] An experiment on K2Pb2(imda)2·4H2O prepared in Example 1 was carried out using TG-DTG with a heating rate of 10℃ / min and a high-purity N2 atmosphere. The TG-DTG curve of K2Pb2(imda)2·4H2O is as shown in the appendix Figure 6 shown. The TG-DTG curve shows that the weight loss around 110℃ is the removal of adsorbed water. The complex starts to lose weight around 310℃, and the framework starts to collapse, with a total of three stages of weight loss. The TG curve shows that the thermal stability of K2Pb2(imda)2·4H2O reaches 310℃.

[0055] K2Pb2(imda)2·H2O (10 wt%) was used as a catalyst and uniformly mixed with AP (90 wt%), and tested by DTA under the condition of a heating rate of 10℃ / min, and the result as shown in Figure 7From the DTA curve, it can be seen that after adding K2Pb2(imda)2·4H2O, the high-temperature decomposition peak of AP is advanced by 73.6 °C, indicating good catalytic performance.

[0056] In summary, K2Pb2(imda)2·4H2O in the present invention has good stability, and at the same time contains K + , Pb 2+ ions, which have flame extinction and catalytic effects; and its preparation method is simple, enabling large-scale industrial production.

[0057] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be construed as limiting the claims involved.

Claims

1. A method for preparing an imidazole carboxylic acid multifunctional bimetallic organic framework material, characterized in that: The chemical formula of the imidazole carboxylic acid multifunctional bimetallic organic framework material is K2Pb2(imda)2·4H2O; The preparation method of the imidazole carboxylic acid multifunctional bimetallic organic framework material comprises the following steps: (1) Weigh a certain proportion of H3imda and add a certain amount of distilled water to prepare a ligand solution; (2) Then, a certain amount of KOH solution is added to the ligand solution in step (1), stirred until a clear solution is obtained, and a mixture is prepared, and the mixture is transferred to a hydrothermal reactor; (3) Add a certain amount of Pb(NO3)2 to the mixture in step (2) while stirring to obtain a flocculent precipitate. After the hydrothermal kettle is assembled, place it in a programmable temperature-controlled oven; (4) The hydrothermal reactor was heated from room temperature to 90°C in an oven for 30 min, then kept at this temperature for 12 h, and then cooled to room temperature at a rate of 5°C / h. The oven was closed and the reactor was removed. (5) The experimental sample was washed three times with water and ethanol respectively, and then dried in an oven at 60°C for 12 h to obtain white spherical crystal particles; The molar ratio of H3imda:Pb(NO3)2:KOH is 4:1:

10.

2. The method for preparing the imidazole carboxylic acid multifunctional bimetallic organic framework material according to claim 1, wherein: The crystal structure of the imidazole carboxylic acid multifunctional bimetallic organic framework material obtained by this method was tested, and the test results are as follows: 。 3. The method for preparing the imidazole carboxylic acid multifunctional bimetallic organic framework material according to claim 1, wherein: The water in step (5) is distilled water.

4. The method for preparing the imidazole carboxylic acid multifunctional bimetallic organic framework material according to claim 1, wherein: The H3imda content in step (1) is 32.18 mg, and the distilled water content is 4 mL; the KOH solution concentration in step (2) is 1 mol / L, and the added amount is 0.5 mL; the Pb(NO3)2 solution concentration in step (3) is 1 mol / L, and the added amount is 50 μL.

5. A catalytic and flame extinguishing effect of the imidazole carboxylic acid multifunctional bimetallic organic framework material obtained by the preparation method of the imidazole carboxylic acid multifunctional bimetallic organic framework material as claimed in claim 1 or 2 in a propellant.

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