A method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by microchannel rapid cooling crystallization
Spherical 3-nitro-1,2,4-triazol-5-one crystals were prepared in a tortuous reactor using a microchannel rapid cooling crystallization technique. This technique solves the problem of preparing crystals with small particle size and regular morphology in existing technologies, and realizes an efficient and simple preparation method suitable for mass production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGBEI UNIV
- Filing Date
- 2023-11-27
- Publication Date
- 2026-06-09
Smart Images
Figure CN117567383B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of energetic crystal materials technology, and in particular to a method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by rapid cooling crystallization in microchannels. Background Technology
[0002] 3-nitro-1,2,4-triazol-5-one (C2H2N4O3, NTO), as a representative of the new generation of high-energy insensitive energetic materials, has become one of the research hotspots for explosives researchers both domestically and internationally in recent years, since its development as an energetic material by the Los Alamos laboratory in 1983. NTO explosive has a density as high as 1.93 g / cm³. 3 Theoretically, NTO has a detonation energy close to that of RDX, a sensitivity close to that of TATB, thermal stability, and insensitivity to external stimuli. It offers superior safety performance compared to B explosives, and its energy is comparable to B explosives, while also being inexpensive. However, typical NTO crystals are serrated, rod-like, resulting in poor formability and low charge density in the mixed explosive, thus limiting its applications.
[0003] Reports indicate that after ultrafine processing, NTO crystals change from rod-shaped to cubic, significantly reducing their mechanical sensitivity and increasing their detonation velocity. Furthermore, the regular morphology of NTO crystals facilitates filling and reduces interparticle spacing, leading to increased charge density and energy release per unit volume, which can improve the performance of mixed explosives to some extent. Therefore, the preparation of NTO particles with smaller diameters and regular morphologies has become a focus of attention for many researchers.
[0004] Existing recrystallization refining technologies mainly include spray drying, vacuum distillation, and supercritical methods. Although these technologies can refine particles to a certain extent, they are complex, require harsh experimental conditions, and the resulting NTO crystals are needle-shaped or irregular rod-shaped, resulting in poor flowability. Summary of the Invention
[0005] In view of this, the purpose of this invention is to provide a method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by rapid cooling crystallization in microchannels. The preparation method provided by this invention is simple to operate, the experimental conditions are easy to adjust, and the prepared 3-nitro-1,2,4-triazol-5-one crystals have high sphericity, uniform particle size, and good flowability.
[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0007] This invention provides a method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by rapid cooling crystallization in microchannels, comprising the following steps:
[0008] A saturated solution of 3-nitro-1,2,4-triazol-5-one is continuously passed into a tortuous reactor for cooling and crystallization to obtain an explosive suspension; the temperature of the saturated solution of 3-nitro-1,2,4-triazol-5-one is 77-82°C, and the cooling and crystallization temperature is -22--17°C.
[0009] The explosive suspension was subjected to solid-liquid separation, washing, and drying to obtain the spherical 3-nitro-1,2,4-triazol-5-one crystals.
[0010] Preferably, the solvent for the saturated solution of 3-nitro-1,2,4-triazol-5-one is N-methylpyrrolidone.
[0011] Preferably, the flow rate of the saturated solution of 3-nitro-1,2,4-triazol-5-one is 0.3 to 0.8 mL / min.
[0012] Preferably, the saturated solution of 3-nitro-1,2,4-triazol-5-one is introduced into the tortuous reactor by a high-pressure plunger pump or a syringe pump.
[0013] Preferably, the residence time of the saturated solution of 3-nitro-1,2,4-triazol-5-one in the tortuous reactor is 14.13 to 37.67 min.
[0014] Preferably, the drying is freeze drying.
[0015] Preferably, the particle size range of the spherical 3-nitro-1,2,4-triazol-5-one crystals is 33–55 μm.
[0016] This invention provides a method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by rapid cooling crystallization in a microchannel, comprising the following steps: continuously passing a saturated solution of 3-nitro-1,2,4-triazol-5-one into a tortuous reactor for cooling crystallization to obtain an explosive suspension; the temperature of the saturated solution of 3-nitro-1,2,4-triazol-5-one is 77–82°C, and the cooling crystallization temperature is -22–-17°C; the explosive suspension is subjected to solid-liquid separation, washing, and drying to obtain the spherical 3-nitro-1,2,4-triazol-5-one crystals. This invention's rapid cooling crystallization in a microchannel introduces microreaction technology into cooling crystallization technology, possessing superior mass and heat transfer characteristics, high controllability, good operability, and high safety compared to traditional batch reactor systems. The spherical 3-nitro-1,2,4-triazol-5-one crystals prepared by the method of this invention have high sphericity, narrow particle size distribution (particle size range of 33-55 μm), and good flowability. Furthermore, the method of this invention is simple to operate, the experimental conditions are easy to adjust, and it has the effectiveness and high reproducibility of product preparation, which is conducive to the effective and stable batch preparation of spherical 3-nitro-1,2,4-triazol-5-one crystals. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the overall system for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals in an embodiment of the present invention. Figure 1 In the diagram, 1-solution gas collecting bottle, 2-high pressure plunger pump or injection pump, 3-curved reactor, 4-crystallized product gas collecting bottle;
[0018] Figure 2 SEM image of the NTO crystal prepared in Example 1;
[0019] Figure 3 SEM image of the NTO crystal prepared in Example 2;
[0020] Figure 4 SEM image of the NTO crystal prepared for Comparative Example 1;
[0021] Figure 5 SEM image of the NTO crystal prepared for Comparative Example 2;
[0022] Figure 6 SEM image of the NTO crystal prepared for Comparative Example 3; Detailed Implementation
[0023] This invention provides a method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by rapid cooling crystallization in microchannels, comprising the following steps:
[0024] A saturated solution of 3-nitro-1,2,4-triazol-5-one is continuously passed into a tortuous reactor for cooling and crystallization to obtain an explosive suspension; the temperature of the saturated solution of 3-nitro-1,2,4-triazol-5-one is 77-82°C, and the cooling and crystallization temperature is -22--17°C.
[0025] The explosive suspension was subjected to solid-liquid separation, washing, and drying to obtain the spherical 3-nitro-1,2,4-triazol-5-one crystals.
[0026] In this invention, a saturated solution of 3-nitro-1,2,4-triazol-5-one (i.e., NTO) is passed through a tortuous reactor for cooling and crystallization to obtain an explosive suspension. In this invention, the solvent for the saturated solution of 3-nitro-1,2,4-triazol-5-one is preferably N-methylpyrrolidone.
[0027] In this invention, the flow rate of the saturated solution of 3-nitro-1,2,4-triazol-5-one is preferably 0.3–0.8 mL / min, more preferably 0.4–0.6 mL / min, and even more preferably 0.5 mL / min. In an embodiment of this invention, the saturated solution of 3-nitro-1,2,4-triazol-5-one is introduced into a tortuous reactor under the action of a high-pressure plunger pump or a syringe pump.
[0028] In this invention, the tortuous reactor is a microreactor. In this embodiment, the tortuous reactor is provided by Efliner Chemical Technology (Shanghai) Co., Ltd., model number 0211-2-0321-F, and the permissible fluid volume of the tortuous reactor is 11.3 mL.
[0029] In this invention, the temperature of the saturated solution of 3-nitro-1,2,4-triazol-5-one is 77–82°C, preferably 78–81°C, and more preferably 80°C. In this invention, the cooling crystallization temperature is -22–-17°C, preferably -21–-19°C, and more preferably -20°C. This invention achieves the control of crystal morphology and particle size distribution by controlling the solvent type, initial temperature, solution flow rate, and crystallization temperature of the saturated solution of 3-nitro-1,2,4-triazol-5-one.
[0030] In this invention, the residence time of the saturated solution of 3-nitro-1,2,4-triazol-5-one in the tortuous reactor is preferably 14.13–37.67 min. In the microchannel rapid cooling crystallization system formed by the tortuous reactor, the supersaturation of the crystallization system increases sharply, generating more micro-solidification nuclei in the solution. The nucleus generation rate is slow, and crystal growth dominates, which is conducive to the formation of crystals with larger particle size and regular morphology. At the same time, the large solution flow rate in the microchannel polishes the accumulated bulk material, resulting in spherical NTO particles with micropores on the surface.
[0031] After obtaining the explosive suspension, the present invention performs solid-liquid separation, washing, and drying on the explosive suspension to obtain the spherical 3-nitro-1,2,4-triazol-5-one crystals. The present invention does not have any particular requirements for the solid-liquid separation method; any method well-known to those skilled in the art can be used. The washing is preferably water washing; the drying is preferably freeze drying.
[0032] Figure 1 This is a schematic diagram of the overall system for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals in an embodiment of the present invention. Figure 1 In the diagram, 1-solution gas collecting bottle, 2-high-pressure plunger pump or syringe pump, 3-curved reactor, 4-crystallized product gas collecting bottle, wherein solution gas collecting bottle 1 and high-pressure plunger pump or syringe pump 2 constitute a fluid drive system, and curved reactor 3 constitutes a micro-reaction system. Figure 1 The overall system for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals shown is arranged in series.
[0033] In the embodiments of the present invention, the following methods are utilized: Figure 1 The specific steps for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals in the system shown are as follows:
[0034] After the solvent is flushed through the microchannels of the system multiple times with a high-pressure plunger pump or injection pump 2 until it is colorless, the solvent in the microchannels is pumped out with a high-pressure plunger pump or injection pump 2 until there is no residue. Then the crystallization temperature in the curved reactor 3 is set to -22 to -17°C and pre-cooled for 30 to 70 minutes.
[0035] Prepare a saturated solution of 3-nitro-1,2,4-triazol-5-one at a temperature of 77–82 °C, place it in solution gas collecting bottle 1, and keep it at this temperature for 20 min.
[0036] The flow rate of the saturated solution of 3-nitro-1,2,4-triazol-5-one was set to 0.3-0.8 mL / min. The saturated solution of 3-nitro-1,2,4-triazol-5-one was pumped into the curved reactor 3 under the action of a high-pressure plunger pump or injection pump 2 for cooling and crystallization.
[0037] The explosive suspension collected from the curved reactor 3 and placed in the gas collecting bottle 4 is subjected to solid-liquid separation, washing, and drying to obtain the spherical 3-nitro-1,2,4-triazol-5-one crystals.
[0038] This invention, microchannel rapid cooling crystallization, introduces microreaction technology into cooling crystallization, offering superior mass and heat transfer characteristics, high controllability, good operability, and high safety compared to traditional batch reaction systems. It is simple to operate, with easily adjustable experimental conditions, and provides effective and highly reproducible product preparation. It is particularly suitable for screening and optimizing experimental parameters in the process of controlling the morphology and particle size of NTO crystals. The spherical 3-nitro-1,2,4-triazol-5-one crystals prepared using this method exhibit high sphericity, narrow particle size distribution (33–55 μm), and good flowability. Furthermore, this method facilitates the efficient and stable batch preparation of spherical 3-nitro-1,2,4-triazol-5-one crystals.
[0039] To further illustrate the present invention, the method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by rapid cooling crystallization in microchannels provided by the present invention is described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.
[0040] The N-methylpyrrolidone (analytical grade) used in the examples was sourced from Tianjin Dingshengxin Chemical Co., Ltd., and the dimethyl sulfoxide (analytical grade) was sourced from Tianjin Fengchuan Chemical Reagent Technology Co., Ltd. All these analytical grade reagents were ready for use without further purification. The tortuous reactor was provided by Efund Chemical Technology (Shanghai) Co., Ltd., model number 0211-2-0321-F. The morphology of the samples in the examples was obtained by scanning electron microscopy using a TescanMira 3LMH from Tescan GmbH, Czech Republic.
[0041] Example 1
[0042] A microchannel rapid cooling crystallization technique for preparing spherical 3-nitro-1,2,4-triazol-5-one (NTO) crystals (apparatus such as...) Figure 1 The parameters are as follows:
[0043] The solvent was N-methylpyrrolidone (NMP), the initial temperature of the saturated NTO solution was 80℃, the flow rate was 0.5 mL / min, and the crystallization temperature was -20℃.
[0044] The specific preparation steps are as follows:
[0045] (1) After flushing the microchannel with NMP multiple times until it is colorless using a high-pressure plunger pump, pump the solvent out of the microchannel until there is no residue, set the crystallization temperature to -20℃, and pre-cool for 30 minutes.
[0046] (2) Prepare 10 mL of saturated NTO solution (solvent is NMP) at 80℃, place it in a gas collecting bottle and keep it warm for 20 min;
[0047] (3) Set the flow rate of the NTO saturated solution to 0.5 mL / min, and pump the NTO saturated solution into the micro-reaction system through a high-pressure plunger pump for cooling and crystallization in the curved reactor;
[0048] (4) Pour the collected explosive suspension into a sand core funnel, then turn on the circulating water vacuum pump to filter and wash, and then put it into a freeze dryer to dry, to obtain a fine explosive powder product, namely the spherical NTO crystal.
[0049] The refined product was characterized under a scanning electron microscope (SEM), and the SEM images are shown below. Figure 2 As shown. By Figure 2 It can be seen that the obtained product has a particle size distribution of 33.6 to 54.2 μm, has micropores on the surface, and is a spherical NTO crystal with an aspect ratio of 0.95 composed of needle-like crystal arrays arranged radially outward from the center.
[0050] Example 2
[0051] A microchannel rapid cooling crystallization technique for preparing spherical 3-nitro-1,2,4-triazol-5-one (NTO) crystals (apparatus such as...) Figure 1 The parameters are as follows:
[0052] The solvent was N-methylpyrrolidone (NMP), the initial temperature of the saturated NTO solution was 78℃, the flow rate was 0.5 mL / min, and the crystallization temperature was -20℃.
[0053] The specific preparation steps are as follows:
[0054] (1) After flushing the microchannel with NMP multiple times until it is colorless using a high-pressure plunger pump, pump the solvent out of the microchannel until there is no residue, set the crystallization temperature to -20℃, and pre-cool for 30 minutes.
[0055] (2) Prepare 10 mL of saturated NTO solution (solvent is NMP) at 78℃, place it in a gas collecting bottle and keep it warm for 20 min;
[0056] (3) Set the flow rate of the NTO saturated solution to 0.5 mL / min, and pump the NTO saturated solution into the micro-reaction system through a high-pressure plunger pump for cooling and crystallization in the curved reactor;
[0057] (4) Pour the collected explosive suspension into a sand core funnel, then turn on the circulating water vacuum pump to filter and wash, and then put it into a freeze dryer to dry, to obtain a fine explosive powder product, namely the spherical NTO crystal.
[0058] The refined product was characterized under a scanning electron microscope (SEM), and the SEM images are shown below. Figure 3 As shown. By Figure 3It can be seen that the obtained product is a spherical NTO crystal with a particle size distribution of 31.5 to 45 μm.
[0059] Comparative Example 1
[0060] A microchannel rapid cooling crystallization technique for preparing NTO crystals (device such as...) Figure 1 The parameters are as follows:
[0061] The solvent was dimethyl sulfoxide (DMSO), the initial temperature of the saturated NTO solution was 80℃, the flow rate was 0.5 mL / min, and the crystallization temperature was -20℃.
[0062] The specific preparation steps are as follows:
[0063] (1) After rinsing the microchannel with DMSO multiple times until it is colorless using a high-pressure plunger pump, pump the solvent out of the microchannel until there is no residue, set the crystallization temperature to -20℃, and pre-cool for 30 minutes.
[0064] (2) Prepare 10 mL of saturated NTO solution (solvent is DMSO) at 80℃, place it in a gas collecting bottle and keep it warm for 20 min;
[0065] (3) Set the flow rate of the NTO saturated solution to 0.5 mL / min, and pump the NTO saturated solution into the micro-reaction system through a high-pressure plunger pump for cooling and crystallization in the curved reactor;
[0066] (4) Pour the collected explosive suspension into a sand core funnel, then turn on the circulating water vacuum pump to filter and wash, and then put it into a freeze dryer to dry, to obtain a fine explosive powder product, namely the spherical NTO crystal.
[0067] The collected refined products were characterized using a scanning electron microscope (SEM). The SEM images are shown below. Figure 4 As shown. By Figure 4 It can be seen that the obtained products are a small number of spherical, and most of them are smooth-surfaced plate-shaped and block-shaped NTO crystals.
[0068] Comparative Example 2
[0069] A microchannel rapid cooling crystallization technique for preparing spherical NTO crystals (device as follows) Figure 1 The parameters are as follows:
[0070] The solvent was N-methylpyrrolidone (NMP), the initial temperature of the saturated NTO solution was 80℃, the flow rate was 5.0 mL / min, and the crystallization temperature was -20℃.
[0071] The specific preparation steps are as follows:
[0072] (1) After flushing the microchannel with NMP multiple times until it is colorless using a high-pressure plunger pump, pump the solvent out of the microchannel until there is no residue, set the crystallization temperature to -20℃, and pre-cool for 30 minutes.
[0073] (2) Prepare 10 mL of saturated NTO solution (solvent is NMP) at 80℃, place it in a gas collecting bottle and keep it warm for 20 min;
[0074] (3) Set the flow rate of the NTO saturated solution to 5.0 mL / min, and pump the NTO saturated solution into the micro-reaction system through a high-pressure plunger pump for cooling and crystallization in the curved reactor;
[0075] (4) Pour the collected explosive suspension into a sand core funnel, then turn on the circulating water vacuum pump to filter and wash, and then put it into a freeze dryer to dry, to obtain a fine explosive powder product, namely the spherical NTO crystal.
[0076] The collected refined products were characterized under a scanning electron microscope (SEM), and the SEM images are shown below. Figure 5 As shown. By Figure 5 It can be seen that the obtained product has a relatively high sphericity, but its surface is covered with a small number of needle-like crystals, and there are many plate-like NTO crystals scattered around it.
[0077] Comparative Example 3
[0078] A microchannel rapid cooling crystallization technique for preparing spherical NTO crystals (device as follows) Figure 1 The parameters are as follows:
[0079] The solvent was N-methylpyrrolidone (NMP), the initial temperature of the saturated NTO solution was 80℃, the flow rate was 0.5 mL / min, and the crystallization temperature was -5℃.
[0080] The specific preparation steps are as follows:
[0081] (1) After flushing the microchannel with NMP multiple times until it is colorless using a high-pressure plunger pump, pump the solvent out of the microchannel until there is no residue, set the crystallization temperature to -5℃, and pre-cool for 30 minutes.
[0082] (2) Prepare 10 mL of saturated NTO solution (solvent is NMP) at 80℃, place it in a gas collecting bottle and keep it warm for 20 min;
[0083] (3) Set the flow rate of the NTO saturated solution to 0.5 mL / min, and pump the NTO saturated solution into the micro-reaction system through a high-pressure plunger pump for cooling and crystallization in the curved reactor;
[0084] (4) Pour the collected explosive suspension into a sand core funnel, then turn on the circulating water vacuum pump to filter and wash, and then put it into a freeze dryer to dry, to obtain a fine explosive powder product, namely the spherical NTO crystal.
[0085] The collected refined products were characterized under a scanning electron microscope (SEM), and the SEM images are shown below. Figure 6 As shown. By Figure 6 It can be seen that the obtained products are mostly plate-shaped crystals with a small number of needle-shaped crystals attached to the surface, and a small number are irregular NTO block particles formed by the aggregation of rod-shaped crystals.
[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing spherical 3-nitro-1,2,4-triazol-5-one crystals by microchannel cooling crystallization, characterized in that, Includes the following steps: A saturated solution of 3-nitro-1,2,4-triazol-5-one is continuously passed into a tortuous reactor for cooling and crystallization to obtain an explosive suspension. The temperature of the saturated solution of 3-nitro-1,2,4-triazol-5-one is 77~82℃, and the cooling and crystallization temperature is -22~-17℃. The solvent of the saturated solution of 3-nitro-1,2,4-triazol-5-one is N-methylpyrrolidone. The flow rate of the saturated solution of 3-nitro-1,2,4-triazol-5-one is 0.3~0.8 mL / min. The explosive suspension was subjected to solid-liquid separation, washing, and drying to obtain the spherical 3-nitro-1,2,4-triazol-5-one crystals; the drying was freeze-drying.
2. The method according to claim 1, characterized in that, The saturated solution of 3-nitro-1,2,4-triazol-5-one is fed into the curved reactor by a high-pressure plunger pump or injection pump.
3. The method according to claim 1, characterized in that, The residence time of the saturated solution of 3-nitro-1,2,4-triazol-5-one in the tortuous reactor is 14.13~37.67 min.
4. The method according to claim 1, characterized in that, The spherical 3-nitro-1,2,4-triazol-5-one crystals have a particle size range of 33~55 μm.