Preparation method of ammonium perchlorate with hollow spherical structure

Abstract

The invention discloses a preparation method of ammonium perchlorate with a hollow spherical structure, which comprises the following steps: firstly, dissolving ammonium perchlorate in a high-temperature N, N-dimethylformamide solvent to form a high-temperature ammonium perchlorate saturated solution; then, adding a high-temperature saturated ammonium perchlorate solution into a low-temperature carbon tetrachloride anti-solvent at a slow feeding rate, and recrystallizing; and finally, completely crystallizing, standing, separating, washing and drying the product to obtain the ammonium perchlorate with the hollow spherical structure. The particle size of the obtained ammonium perchlorate with the hollow spherical structure is 50-100 microns, and the ammonium perchlorate is high in sphericity degree and good in dispersity. The ammonium perchlorate with the hollow spherical structure is applied to the fields of propellants, pyrotechnic compounds, thermite and the like.

Description

Technical Field

[0001] The invention relates to a preparation method, in particular to a preparation method of ammonium perchlorate with a hollow spherical structure. Background Art

[0002] Ammonium perchlorate is a strong oxidant widely used in propellants, pyrotechnics, thermite, etc. The morphology of ammonium perchlorate has a great influence on its sensitivity, charge density, and thermal decomposition performance.

[0003] At present, researchers have used several crystallization methods to prepare ammonium perchlorate with different morphologies. For example, Dong Qianqian (Study on Preparation of Ultrafine Ammonium Perchlorate by Anti-Solvent Recrystallization, Master's Thesis, 2015) used N,N-dimethylformamide as ammonium perchlorate solvent and ethyl acetate as anti-solvent at room temperature to crystallize and prepare wedge-shaped ammonium perchlorate. CN118637561A first dissolved ammonium perchlorate in a mixed solution of methanol and triethanolamine, and then precipitated it using anti-solvent octane to obtain ultrafine porous ammonium perchlorate. CN117285009A used N,N-dimethylformamide / dimethyl sulfoxide as a mixed solvent, hexadecyltrimethylammonium bromide as a surfactant, and ethyl acetate as an anti-solvent to obtain one-dimensional needle-shaped ammonium perchlorate using anti-solvent crystallization. CN117285008A added a high-temperature saturated solution of N,N-dimethylformamide containing ammonium perchlorate to a low-temperature anti-solvent of ethyl acetate, and recrystallized to obtain butterfly-shaped micron ammonium perchlorate. CN117285012A uses N,N-dimethylformamide as solvent and ethyl acetate / oleic acid mixed solvent as anti-solvent to obtain two-dimensional disk-shaped micron ammonium perchlorate by anti-solvent crystallization at room temperature.

[0004] Hollow spherical ammonium perchlorate has also attracted much attention in recent years due to its many advantages such as light weight, large specific surface area, and strong design. CN117285011A dissolves ammonium perchlorate in N,N-dimethylformamide (or dimethyl sulfoxide, N-methylpyrrolidone), and then adds it to a high-viscosity oleic acid anti-solvent to crystallize and prepare hollow spherical ammonium perchlorate. Li Lan (Construction and Thermal Decomposition Performance of AP Hierarchical Hollow Microspheres, Journal of Explosives and Propellants, 2021, 44, 769-775) prepared hollow spherical ammonium perchlorate by combining ice template method with freeze-drying technology. In the prior art, hollow structure ammonium perchlorate can only be obtained by relying on cumbersome freeze-drying process or high-viscosity oleic acid anti-solvent.

[0005] It should be noted that Liu Ning (Study on the Preparation of Submicron Ammonium Perchlorate, Master's Thesis, 2013) used N,N-dimethylformamide as solvent, carbon tetrachloride as anti-solvent, lecithin as surfactant, and added dropwise at a rate of 1.0 mL / min to the anti-solvent with a stirring speed of 1000 rpm at room temperature to prepare solid ammonium perchlorate particles with an average particle size of about 8.5 microns. Cheng Zhipeng (J. Ind. Eng. Chem. 135 (2024) 513–521) added N,N-dimethylformamide solution of ammonium perchlorate dropwise at a rate of 3.0 mL / min to the carbon tetrachloride anti-solvent at room temperature to prepare ammonium perchlorate polyhedrons with irregular morphology. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing ammonium perchlorate with a hollow spherical structure. The method has simple process and easy operation. The obtained ammonium perchlorate with a hollow structure has high sphericity, good particle size uniformity and good dispersibility, and is easy to realize large-scale production.

[0007] The technical solution of the present invention is: a method for preparing ammonium perchlorate with a hollow spherical structure, wherein a high-temperature saturated solution of N,N-dimethylformamide in which ammonium perchlorate is dissolved is added to a low-temperature carbon tetrachloride anti-solvent at a slow feeding rate, and recrystallized to obtain ammonium perchlorate with a hollow spherical structure; the method specifically comprises the following steps: Step 1, dissolving ammonium perchlorate in a high-temperature N,N-dimethylformamide solvent to form a high-temperature ammonium perchlorate saturated solution; Step 2, adding a high-temperature ammonium perchlorate saturated solution to a low-temperature carbon tetrachloride anti-solvent at a slow feeding rate for recrystallization; Step 3: After the crystallization is complete, the product is allowed to stand for separation, washed, and dried to obtain ammonium perchlorate with a hollow spherical structure.

[0008] The high temperature of the N,N-dimethylformamide solvent in step 1 is 50-70°C.

[0009] The slow addition rate in step 2 is 0.15-0.6 mL / min.

[0010] The low temperature of carbon tetrachloride in step 2 is -10 to 10°C.

[0011] The volume ratio of the saturated ammonium perchlorate solution to carbon tetrachloride in step 2 is controlled at 0.01-0.005, and the recrystallization process is carried out under stirring at 400-600 rpm.

[0012] In the step 3, the product is washed with ethyl acetate and dried at 60°C.

[0013] The beneficial effects of the present invention are: 1. The raw materials used are simple, only N,N-dimethylformamide solvent is required and carbon tetrachloride anti-solvent, and the production cost is low.

[0014] 2. It does not involve high viscosity anti-solvents, and the product is easy to wash and has high purity.

[0015] 3. The preparation process is simple, there are few factors affecting the product morphology, and it is easy to control.

[0016] 4. The obtained hollow spherical ammonium perchlorate has a particle size of 50 to 100 microns, high sphericity, good particle size uniformity and good dispersibility.

[0017] 5. The raw material ammonium perchlorate is industrial ammonium perchlorate, which has no restrictions on particle size, morphology or crystal form.

[0018] 6. The process parameters, product morphology and particle size involved in the present invention are significantly different from those in the existing literature. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope image of the hollow spherical ammonium perchlorate obtained in Example 1; Figure 2 This is a scanning electron microscope image of the hollow spherical ammonium perchlorate obtained in Example 2; Figure 3 This is a scanning electron microscope image of the hollow spherical ammonium perchlorate obtained in Example 3; Figure 4 This is a scanning electron microscope image of the ammonium perchlorate obtained in Comparative Example 1; Figure 5 This is a scanning electron microscope image of the ammonium perchlorate obtained in Comparative Example 2; Figure 6 This is a scanning electron microscope image of the ammonium perchlorate obtained in Comparative Example 3; DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further illustrated below in conjunction with embodiments and comparative examples, but they should not be construed as limitations on the technical solution, and all adaptive improvements based on these examples fall within the protection scope of the present invention.

[0021] Example 1: Preparation of hollow spherical ammonium perchlorate as follows Step 1, dissolving ammonium perchlorate in N,N-dimethylformamide solvent at a temperature of 60° C. to form a saturated ammonium perchlorate solution; Step 2, adding an ammonium perchlorate solution at a temperature of 60°C to a carbon tetrachloride anti-solvent at a temperature of 0°C at a feeding rate of 0.375 mL / min, and recrystallizing; wherein the volume ratio of the saturated ammonium perchlorate solution to the carbon tetrachloride is controlled at 0.0075, and the recrystallization process is carried out under stirring at 500 rpm; Step 3: After the crystallization is complete, the product is allowed to stand for separation, washed with ethyl acetate, and dried at 60°C to obtain ammonium perchlorate with a hollow spherical structure. The results of the scanning electron microscope are as follows: Figure 1 shown.

[0022] Example 2: Preparation of hollow spherical ammonium perchlorate as follows Step 1, dissolving ammonium perchlorate in N,N-dimethylformamide solvent at a temperature of 50° C. to form a saturated ammonium perchlorate solution; Step 2, adding a saturated ammonium perchlorate solution at a temperature of 50° C. to a carbon tetrachloride anti-solvent at a temperature of −10° C. at a feeding rate of 0.15 mL / min, and recrystallizing; wherein the volume ratio of the saturated ammonium perchlorate solution to the carbon tetrachloride is controlled at 0.005, and the recrystallization process is carried out under stirring at 400 rpm; Step 3: After the crystallization is complete, the product is allowed to stand for separation, washed with ethyl acetate, and dried at 60°C to obtain ammonium perchlorate with a hollow spherical structure. The results of the scanning electron microscope are as follows: Figure 2 shown.

[0023] Example 3: Preparation of hollow spherical ammonium perchlorate as follows Step 1, dissolving ammonium perchlorate in N,N-dimethylformamide solvent at a temperature of 70° C. to form a saturated ammonium perchlorate solution; Step 2, adding a saturated ammonium perchlorate solution at a temperature of 70°C to a carbon tetrachloride anti-solvent at a temperature of 10°C at a feeding rate of 0.6 mL / min, and recrystallizing; wherein the volume ratio of the saturated ammonium perchlorate solution to the carbon tetrachloride is controlled at 0.01, and the recrystallization process is carried out under stirring at 600 rpm; Step 3: After the crystallization is complete, the product is allowed to stand for separation, washed with ethyl acetate, and dried at 60°C to obtain ammonium perchlorate with a hollow spherical structure. The results of the scanning electron microscope are as follows: Figure 3 shown.

[0024] Provided by Examples 1-3 Figure 1-3 It can be seen that the hollow spherical ammonium perchlorate obtained by the present invention has a particle size of 50 to 100 microns, high sphericity, good particle size uniformity and good dispersibility.

[0025] Comparative Example 1: The temperature of the N,N-dimethylformamide solvent in Example 1 was reduced to 25°C, and other conditions remained unchanged. The scanning electron microscopy of the obtained product is as follows: Figure 4 shown.

[0026] The comparative example 1 provides Figure 4 It can be seen that the obtained product includes ammonium perchlorate with a hollow spherical structure and some fragmented ammonium perchlorate crystals. It can be seen that the use of a high-temperature solution in the process of the present invention is conducive to the preparation of ammonium perchlorate with a uniform hollow spherical structure.

[0027] Comparative Example 2: The feed rate in Example 1 was increased to 1 mL / min, and other conditions remained unchanged. The scanning electron microscopy of the obtained product is as follows Figure 5 shown.

[0028] The comparative example 2 provides Figure 5 It can be seen that the obtained product is ammonium perchlorate with irregular morphology, and ammonium perchlorate with a hollow spherical structure cannot be obtained. It can be seen that the slow feeding rate is crucial to the formation of ammonium perchlorate with a hollow spherical structure in the process of the present invention.

[0029] Comparative Example 3: The temperature of the carbon tetrachloride antisolvent in Example 1 was raised to 25°C, and other conditions remained unchanged. The scanning electron microscopy of the obtained product is as follows: Figure 6 shown.

[0030] The comparative example 3 provides Figure 6 It can be seen that the obtained product is ammonium perchlorate with irregular morphology, and ammonium perchlorate with a hollow spherical structure cannot be obtained. It can be seen that the low anti-solvent temperature is helpful to form ammonium perchlorate with a hollow spherical structure in the process of the present invention.

Claims

1. A method for preparing hollow spherical ammonium perchlorate, characterized in that: The method comprises the following steps: adding a high-temperature saturated solution of N,N-dimethylformamide containing ammonium perchlorate to a low-temperature carbon tetrachloride anti-solvent at a slow feeding rate, and recrystallizing to obtain ammonium perchlorate with a hollow spherical structure; Step 1, dissolving ammonium perchlorate in a high-temperature N,N-dimethylformamide solvent to form a high-temperature ammonium perchlorate saturated solution; Step 2, adding a high-temperature ammonium perchlorate saturated solution to a low-temperature carbon tetrachloride anti-solvent at a slow feeding rate for recrystallization; Step 3: After the crystallization is complete, the product is allowed to stand for separation, washed, and dried to obtain ammonium perchlorate with a hollow spherical structure.

2. The method for preparing a hollow spherical ammonium perchlorate according to claim 1, characterized in that: The high temperature of the N,N-dimethylformamide solvent in step 1 is 50-70°C.

3. The method for preparing a hollow spherical ammonium perchlorate according to claim 1, characterized in that: The slow addition rate in step 2 is 0.15-0.6 mL / min.

4. The method for preparing a hollow spherical ammonium perchlorate according to claim 1, characterized in that: The low temperature carbon tetrachloride in step 2 is -10 to 10°C.

5. The method for preparing a hollow spherical ammonium perchlorate according to claim 1, characterized in that: The volume ratio of the saturated ammonium perchlorate solution to carbon tetrachloride in step 2 is controlled at 0.01-0.005, and the recrystallization process is carried out under stirring at 400-600 rpm.

6. The method for preparing a hollow spherical ammonium perchlorate according to claim 1, characterized in that: In the step 3, the product is washed with ethyl acetate and dried at 60°C.

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