An ultrasonic micro-reaction system and method for preparing epsilon-CL-20 by continuous recrystallization

Abstract

The application discloses a kind of continuous recrystallization preparation ε-CL-20 ultrasonic microreaction system and method, belong to micro chemical technology, ultrasonic application technical field.This application is different crystal form CL-20 as raw material, with acetone, ethyl acetate as CL-20 good solvent, with toluene, n-octane, n-heptane, ligroin as anti-solvent, by continuous conveying equipment in microreactor mixing, while applying specific frequency and power ultrasonic.Ultrasonic cavitation causes fluid turbulence to strengthen the mixing between fluids, accelerate CL-20 precipitation, improve the process efficiency of CL-20 from metastable β crystal form to stable ε crystal form transition, and the purity of ε-CL-20 crystal form in recrystallization product.This application shortens the CL-20 crystal form transition time (prior art is 10-200min), realizes continuous production, and is easy to integrate and parallel amplification.

Description

Technical Field

[0001] This application relates to an ultrasonic microreaction system and method for the continuous crystallization preparation of ε-CL-20, belonging to the fields of microchemical technology and ultrasonic application technology. Background Technology

[0002] Hexanitrohexaazaisowulzane (CL-20), as the non-nuclear elemental explosive with the highest energy density currently available, can significantly enhance the combat effectiveness of weapons and equipment and profoundly influence future warfare methods and international military deployments. Among the many crystal forms of CL-20, the ε-form is the most practically valuable due to its highest crystal density and thermodynamic stability. The CL-20 synthesized by the current Nielson process is mainly in the metastable α / γ form, requiring crystal form conversion treatment to the target ε-form. In industrial production, the antisolvent recrystallization method is commonly used to prepare high-purity ε-form CL-20 crystals. A supersaturated solution is formed by mixing the solvent and antisolvent. This process follows the phase transition law of "kinetic preferential precipitation - thermodynamic stable reconstruction": initially, the metastable β-form preferentially nucleates, and the solution remains in a supersaturated state of ε-form. Once the ε-nucleus overcomes the energy barrier and forms, the β-form CL-20 dissolves and achieves ε-form reconstruction through Ostwald ripening. The stable nucleus formation stage, due to the need to overcome the energy barrier, becomes the key link restricting the crystal conversion efficiency. To address this, the academic community has developed enhancement strategies such as template induction, magnetic induction, and ultrasonic induction. Among them, ultrasonic induction technology promotes molecular conformational recombination by generating local high temperature and pressure through cavitation bubbles, which can reduce the crystallization time from tens of hours in traditional processes to several hours.

[0003] Ultrasonic cavitation is essentially a nonlinear coupling process of sound field and bubble dynamics, and its spatiotemporal heterogeneity poses a severe challenge to crystal form control. In conventional batch reactors, the sound field intensity decreases exponentially with radiation distance. This spatial sound intensity gradient leads to differences in crystal form transformation rates in different regions, directly affecting the crystal form purity of the product. At the same time, the nucleation-growth process of CL-20 crystals is highly sensitive to the concentration field and temperature field. Unfortunately, the heat and mass transfer rate in traditional batch reactors is limited, and the acoustic cavitation process is subject to randomness, which easily leads to problems such as uneven product morphology and poor batch stability. To achieve efficient continuous preparation of ε-CL-20, two major technical bottlenecks need to be overcome: (1) Constructing a uniformly distributed sound field and cavitation field to ensure that different regions of the reactor have the same crystal form transformation rate; (2) Developing a new type of reactor to improve the heat and mass transfer rate of the crystallization process and achieve precise control of the concentration / temperature field.

[0004] In summary, traditional CL-20 crystallization processes often employ batch reactors with slow, dropwise addition, resulting in low operational safety and long processing times. Therefore, it is necessary to propose a rapid, continuous crystallization method for preparing ε-CL-20. Summary of the Invention

[0005] To overcome the problems of long crystallization time, non-uniform particle size, and poor batch-to-batch repeatability in traditional batch reactors, this application proposes a technical solution for the recrystallization preparation of high-purity ε-CL-20 using an ultrasonic microreactor. Compared to traditional batch reactor crystallization equipment, the sub-millimeter channel characteristics of the microreactor ensure a two-order-of-magnitude improvement in the heat and mass transfer rate during the CL-20 crystallization process. This inherently safe characteristic provides a physical guarantee for controlling crystal nucleation / growth kinetics and optimizing product performance (morphology, particle size, etc.). Furthermore, the microreactor's characteristic scale forms a good spatial match with the acoustic wavelength and cavitation bubble size. This scale synergy not only overcomes the sound field attenuation problem in traditional sonochemical equipment but also achieves precise spatiotemporal control of the cavitation bubble field. In addition, the continuous operation mode overcomes the inherent defects of batch reactors, thereby significantly improving product batch consistency and process repeatability.

[0006] The technical solution adopted in this application is as follows:

[0007] According to a first aspect of this application, an ultrasonic microreactor system for the continuous crystallization preparation of ε-CL-20 is provided, comprising a raw material supply end, an ultrasonic microreactor, and a product collection end connected in sequence;

[0008] The ultrasonic microreactor includes a sandwich ultrasonic transducer and a microreactor with a hollow cavity, wherein the radiating surface of the sandwich ultrasonic transducer is rigidly connected to the bottom of the microreactor.

[0009] The microreactor is equipped with at least one layer of suspended microreactor plate.

[0010] The micro-reaction plate is equipped with microchannels and turbulence columns.

[0011] The microchannels and turbulence columns inside the suspended microreactor are filled with a circulating temperature-controlled medium; the temperature-controlled medium is used to regulate the reaction temperature.

[0012] The suspended microreactor plate is provided with a temperature-controlled medium inflow channel and a temperature-controlled medium outflow channel leading to the outside of the microreactor;

[0013] The microchannel has a feed channel leading to the outside of the microreactor at its inlet end and a slurry discharge channel leading to the outside of the microreactor at its outlet end.

[0014] When the ultrasonic microreactor is excited, the piezoelectric ceramic stack converts the electrical signal into mechanical vibration, which is then directly transmitted to the microreactor through the front radiation surface of the transducer. This enhances the mixing between fluids, accelerates the recrystallization and crystal transformation of CL-20, and prevents blockage inside the microreactor.

[0015] Optionally, the sandwich ultrasonic transducer includes a front cover plate, a piezoelectric ceramic stack, and a rear cover plate arranged sequentially.

[0016] The front radiating surface of the ultrasonic transducer is the surface of the front cover plate away from the piezoelectric ceramic stack. The front cover plate is typically made of a lightweight metal, such as aluminum, titanium, magnesium, or alloys. The rear cover plate is typically made of a heavy metal, such as stainless steel, copper, or copper-steel alloys. The front cover plate of the sandwich transducer and the microreactor are preferably made of the same metal material. The operating frequency range of the sandwich transducer is preferably 10-100 kHz, and the power is preferably 0-500 W, more preferably 0-200 W.

[0017] Optionally, the length of the microchannel is 5-100cm and the hydraulic diameter is 0.5-5.0mm.

[0018] Optionally, the microreactor is cylindrical, with a diameter of 50-200 mm and a height of 10-400 mm. The microreactor is made of thermally conductive materials, preferably aluminum alloys or titanium.

[0019] Optionally, the microreactor is integrally formed using 3D printing technology and has multiple layers of suspended microreactor plates inside. Each microreactor plate consists of three parts: microchannels, turbulence columns, and a temperature-controlled cavity. The microreactor is rigidly connected to the front radiating surface of the ultrasonic transducer via adhesive bonding. The cross-section of the microchannels is preferably polygonal or circular, and more preferably circular.

[0020] Optionally, the microreactor is hollowed out.

[0021] Optionally, the microreactor is made of a thermally conductive material, preferably aluminum alloy, titanium, etc.

[0022] The microreactor has a solvent inlet, an antisolvent inlet, and a product outlet on its body wall. The inlet has an inner diameter of 0.1-5.0 mm, preferably 0.3-5.0 mm, and an outer diameter of 0.5-10.0 mm, preferably 1.0-10.0 mm. The outlet has an inner diameter of 0.5-5.0 mm, preferably 2.0-5.0 mm, and an outer diameter of 1.0-10.0 mm, preferably 3.0-10.0 mm. The solvent inlet and antisolvent inlet are the inlets of the feed channel, and the product outlet is the outlet of the slurry discharge channel.

[0023] Optionally, the microreactor body wall is provided with inlet and outlet holes to enable rapid inflow and outflow of temperature-controlled media within different layers of the microreactor. The inner diameter of the inlet / outlet hole is 1.0-5.0 mm, preferably 2.0-5.0 mm; the outer diameter is 2.0-10.0 mm, preferably 3.0-10.0 mm. The inlet and outlet holes serve as the inlet for the temperature-controlled media inflow channel and the outlet for the temperature-controlled media outflow channel, respectively.

[0024] The suspended microreactor plate can be placed at any position and in any number within the microreactor, such as at the bottom, top, or middle of the microreactor.

[0025] Optionally, the raw material supply end includes a material storage tank, which is connected to the inlet of the feed channel via a pumping device;

[0026] Optionally, the material storage tank includes a solvent storage tank and an antisolvent storage tank, and the feed channel includes a solvent feed channel and an antisolvent feed channel corresponding to the material storage tank.

[0027] Optionally, the sandwich ultrasonic transducer applies a frequency of 10-100kHz and a power of 0-200W.

[0028] According to a second aspect of this application, a method for preparing ε-CL-20 by continuous crystal transformation using ultrasonic microreactions is provided, comprising the following steps:

[0029] The ultrasonic microreactor system for preparing ε-CL-20 by continuous crystallization as described in any one of claims 1-5 is used to introduce antisolvent material and material containing CL-20 and solvent into the ultrasonic microreactor from the raw material supply end. The materials are mixed and reacted in the microchannel, and the prepared ε-CL-20 product is discharged to the product collection end through the slurry discharge channel.

[0030] Raw materials are supplied through a pumping system. The antisolvent material, the material containing CL-20 and the solvent are mixed in the microchannel and recrystallized to precipitate metastable β-type CL-20, which is then reconstructed into ε-type CL-20 under ultrasonic radiation.

[0031] Optionally, the CL-20 is one or a mixture of at least two of γ-type CL-20, β-type CL-20, and α-type CL-20;

[0032] The solvent is selected from at least one of acetone and ethyl acetate;

[0033] The antisolvent is selected from at least one of toluene, n-octane, n-heptane, and petroleum ether.

[0034] Optionally, the reaction temperature is 15-40°C, and the reaction temperature is regulated by a temperature control medium.

[0035] Optionally, the temperature of the temperature control medium is 15-40℃.

[0036] The residence time of the antisolvent material, the material containing CL-20 and the solvent in the microchannel is 5-600s, preferably 10-300s.

[0037] Optionally, in the material containing CL-20 and solvent, the concentration of CL-20 is 200-800 g / L;

[0038] The volume ratio of antisolvent to solvent in the feed is 0.5-30.0, preferably 1.0-20.0.

[0039] Optionally, the ε-CL-20 product is filtered and dried at the product collection end to obtain a high-purity ε-CL-20 product.

[0040] Optionally, the drying temperature is 20-80℃, preferably 40-60℃.

[0041] The beneficial effects of this application include:

[0042] (1) In the ultrasonic microreactor system for the continuous crystallization preparation of ε-CL-20 provided in this application, the characteristic scale of the ultrasonic microreactor is well spatially matched with the sound wave wavelength and the size of the cavitation bubble. This scale synergy effect overcomes the sound field attenuation problem existing in traditional ultrasonic crystallization equipment. The sound field / bubble field distribution in the reactor is uniform, which solves the problems of uneven crystal transformation progress in different regions of the reactor and low crystal purity of the product faced by the prior art.

[0043] (2) The ultrasonic microreactor used in this application has sub-millimeter channel characteristics that can ensure that the heat and mass transfer rate of the CL-20 crystallization process is increased by two orders of magnitude, which not only ensures the safety of the crystal transformation process, but also provides physical protection for controlling crystal nucleation / growth kinetics and optimizing product performance (morphology, particle size, etc.).

[0044] (3) The ultrasonic microreactor method for preparing ε-CL-20 by continuous crystal transformation provided in this application overcomes the inherent defects of batch reactors through continuous crystal transformation mode, and significantly improves the batch consistency of products and process repeatability.

[0045] (4) The reactor used in this application transmits ultrasonic waves directly to the microreactor. The reactor has a high sound power density, is easy to operate, effectively shortens the recrystallization and crystal transformation time, improves the efficiency of the crystal transformation process, and prevents the recrystallized product from clogging the channel during the production process. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the three-dimensional structure of the ultrasonic microreactor;

[0047] Figure 2 A schematic diagram of the three-dimensional structure of a sandwich-type ultrasonic transducer;

[0048] Figure 3 This is a schematic diagram of the single-layer suspended microreactor structure inside the microreactor;

[0049] Figure 4Flowchart of the process for recrystallizing ε-CL-20.

[0050] Attached Figure Labels

[0051] 1.1 Sandwich-type ultrasonic transducer; 1.2 Microreactor; 2.1 Transducer front cover plate; 2.2 Piezoelectric ceramic crystal stack; 2.3 Transducer rear cover plate; 3.1 Solvent inlet; 3.2 Antisolvent inlet; 3.3 Slurry outlet; 3.4 Temperature-controlled medium inlet; 3.5 Temperature-controlled medium outlet; 3.6 Microchannel; 3.7 Turbulence column; 4.1 Solvent storage tank; 4.2 Antisolvent storage tank; 4.3 First horizontal flow pump; 4.4 Second horizontal flow pump; 4.5 Ultrasonic microreactor; 4.6 Vacuum filter tank. Detailed Implementation

[0052] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0053] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0054] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0055] According to one embodiment of this application, the structure of the ultrasonic microreactor is as follows: Figure 1 The device shown consists of a sandwich-type ultrasonic transducer (1.1) and a microreactor (1.2) connected by epoxy resin adhesive.

[0056] The sandwich-type ultrasonic transducer (1.1) is composed of a transducer front cover plate (2.1), a piezoelectric ceramic crystal stack (2.2), and a transducer rear cover plate (2.3) connected at the center by high-strength metal bolts. The piezoelectric ceramic crystal stack (2.2) is formed by two piezoelectric ceramic sheets coaxially stacked into a cylinder, which are then bonded together with strong adhesive. The transducer rear cover plate (2.3) is made of steel and has a cylindrical shape. The transducer front cover plate (2.1) is made of aluminum alloy and has a conical shape.

[0057] The microreactor (1.2) is made of aluminum alloy and has a single-layer suspended microreactor plate at the center or two single-layer suspended microreactor plates distributed at the bottom and top respectively. Figure 3As shown, the single-layer suspended microreactor is equipped with microchannels (3.6) and turbulence columns (3.7). The surface of the microchannels (3.6) is circular, and the turbulence columns (3.7) are evenly distributed inside the microreactor plate. The microchannel (3.6) has a first feed channel and a second feed channel that penetrate the wall of the microreactor (1.2). The inlet of the first feed channel is a solvent feed hole (3.1), and the inlet of the second feed channel is an antisolvent feed hole (3.2). The outlet of the microchannel (3.6) has a slurry discharge channel that penetrates the wall of the microreactor (1.2). The outlet of the slurry discharge channel is a slurry discharge hole (3.3). The wall of the microreactor (1.2) has a temperature-controlled medium inflow channel and a temperature-controlled medium outflow channel that penetrate into the interior of the microreactor (1.2). The inlet of the temperature-controlled medium inflow channel is a temperature-controlled medium inflow hole (3.4), and the outlet of the temperature-controlled medium outflow channel is a temperature-controlled medium outflow hole (3.5).

[0058] According to one embodiment of this application, an ultrasonic microreactor system for the continuous crystallization preparation of ε-CL-20 comprises a raw material supply end, an ultrasonic microreactor, and a product collection end. The raw material supply end includes a solvent storage tank and an antisolvent storage tank, as well as a horizontal flow pump for supplying the raw material from the storage tanks to the ultrasonic microreactor. The product collection end includes a vacuum filtration tank. The process flow for recrystallization preparation of ε-CL-20 is as follows: Figure 4 As shown, the solvent storage tank (4.1) supplies solvent raw material containing CL-20 into the ultrasonic microreactor through the solvent feed port (3.1) via the first horizontal flow pump (4.3), and the antisolvent storage tank (4.2) supplies antisolvent into the ultrasonic microreactor through the antisolvent feed port (3.2) via the second horizontal flow pump (4.4). At the same time, temperature-controlled medium flows in and out through the temperature-controlled medium inlet port (3.4) and temperature-controlled medium outlet port (3.5) to control the reaction temperature in the microreactor. The two materials mix and react in the ultrasonic microreactor. The product is discharged through the slurry outlet port (3.3) and then enters the vacuum filter tank (4.6) for filtration. After vacuum drying, a solid product is obtained.

[0059] Example 1

[0060] This embodiment is an ultrasonic microreactor with a resonant frequency of 20 kHz, and its structural schematic diagram is shown below. Figure 1 The device shown consists of a sandwich-type ultrasonic transducer (1.1) and a microreactor (1.2) connected by epoxy resin adhesive.

[0061] The sandwich-type ultrasonic transducer (1.1) operates at a frequency of 20 kHz and has a maximum input power of 100 W. The sandwich-type ultrasonic transducer (1.1) consists of a front cover plate (2.1), a piezoelectric ceramic crystal stack (2.2), and a rear cover plate (2.3) connected at the center by high-strength metal bolts. The piezoelectric ceramic crystal stack (2.2) is a cylinder with a thickness of 10 mm, formed by two piezoelectric ceramic sheets coaxially stacked. Each piezoelectric ceramic sheet is 5 mm thick and 45 mm in diameter, and the sheets are bonded together with strong adhesive. The rear cover plate (2.3) is made of steel and has a cylindrical shape with a diameter of 45 mm and a thickness of 35 mm. The front cover plate (2.1) is made of aluminum alloy and has a conical shape with a front radiating surface diameter of 66 mm, a rear radiating surface diameter of 45 mm, and a thickness of 47 mm.

[0062] The microreactor (1.2) is made of aluminum alloy and has two single-layer suspended microreactor plates distributed at the bottom and top, respectively. The microreactor has a diameter of 70 mm and a height of 50 mm. Figure 3 The schematic diagram shows that each single-layer suspended microreactor plate has a height of 12mm. Inside the single-layer suspended microreactor plate are microchannels (3.6) and turbulence columns (3.7). The microchannel (3.6) has a circular surface, a length of 20cm, and a hydraulic diameter of 3.0mm. There are eight turbulence columns (3.7) with a diameter of 6mm, evenly distributed within the microreactor plate. The inlet end of the microchannel (3.6) has a first feed channel and a second feed channel penetrating the wall of the microreactor (1.2). The inlet of the first feed channel is a solvent feed hole (3.1), and the inlet of the second feed channel is an antisolvent feed hole (3.2). The outlet end of the microchannel (3.6) has a slurry discharge channel penetrating the wall of the microreactor (1.2). The inner diameter of the first feed channel, the second feed channel, the solvent feed hole (3.1), and the antisolvent feed hole (3.2) is 1.0 mm, and the outer diameter is 3.0 mm. The inner diameter of the slurry discharge channel and the slurry discharge hole (3.3) is 2.0 mm, and the outer diameter is 5.0 mm. The reactor (1.2) is provided with a temperature-controlled medium inflow channel and a temperature-controlled medium outflow channel that penetrate into the interior of the microreactor (1.2). The inlet end of the temperature-controlled medium channel is the temperature-controlled medium inflow hole (3.4), and the outlet end of the temperature-controlled medium outflow channel is the temperature-controlled medium outflow hole (3.5). The inner diameter of the temperature-controlled medium inflow channel, the temperature-controlled medium inflow hole (3.4), the temperature-controlled medium outflow channel, and the temperature-controlled medium outflow hole (3.5) is 3.0 mm, and the outer diameter is 6.0 mm.

[0063] The temperature-controlled ultrasonic microreactor of this embodiment has a resonant frequency of 20.9 kHz and a maximum input power of 100 W.

[0064] Example 2

[0065] This embodiment is an ultrasonic microreactor with a resonant frequency of 40 kHz, and its structural schematic diagram is shown below. Figure 1 The device shown consists of a sandwich-type ultrasonic transducer (1.1) and a microreactor (1.2) connected by epoxy resin adhesive.

[0066] The sandwich-type ultrasonic transducer (1.1) operates at a frequency of 40 kHz and has a maximum input power of 60 W. The sandwich-type ultrasonic transducer (1.1) consists of a front cover plate (2.1), a piezoelectric ceramic crystal stack (2.2), and a rear cover plate (2.3) connected at the center by high-strength metal bolts. The piezoelectric ceramic crystal stack (2.2) is composed of two coaxially stacked piezoelectric ceramic sheets forming a cylinder with a thickness of 10 mm. Each piezoelectric ceramic sheet is 5 mm thick and 38 mm in diameter, and the sheets are bonded together with strong adhesive. The rear cover plate (2.3) is made of steel and has a cylindrical shape with a diameter of 38 mm and a thickness of 18 mm. The front cover plate (2.1) is made of aluminum alloy and has a conical shape with a front radiating surface diameter of 58 mm, a rear radiating surface diameter of 38 mm, and a thickness of 40 mm.

[0067] The microreactor (1.2) is made of aluminum alloy and has two single-layer suspended microreactor plates distributed at the bottom and top, respectively. The microreactor has a diameter of 60 mm and a height of 30 mm. Figure 3The schematic diagram shows that each single-layer suspended microreactor plate has a height of 15mm. Inside the single-layer suspended microreactor plate are microchannels (3.6) and turbulence columns (3.7). The microchannel (3.6) has a circular surface, a length of 10cm, and a hydraulic diameter of 1.5mm. There are six turbulence columns (3.7) with a diameter of 8mm each, evenly distributed within the microreactor plate. The inlet end of the microchannel (3.6) has a first feed channel and a second feed channel penetrating the wall of the microreactor (1.2). The inlet of the first feed channel is a solvent feed hole (3.1), and the inlet of the second feed channel is an antisolvent feed hole (3.2). The outlet end of the microchannel (3.6) has a slurry discharge channel penetrating the wall of the microreactor (1.2). The inner diameter of the first feed channel, the second feed channel, the solvent feed hole (3.1), and the antisolvent feed hole (3.2) is 0.5 mm, and the outer diameter is 2.0 mm. The inner diameter of the slurry discharge channel and the slurry discharge hole (3.3) is 1.0 mm, and the outer diameter is 3.0 mm. The reactor (1.2) is provided with a temperature-controlled medium inflow channel and a temperature-controlled medium outflow channel that penetrate into the interior of the microreactor (1.2). The inlet end of the temperature-controlled medium channel is the temperature-controlled medium inflow hole (3.4), and the outlet end of the temperature-controlled medium outflow channel is the temperature-controlled medium outflow hole (3.5). The inner diameter of the temperature-controlled medium inflow channel, the temperature-controlled medium inflow hole (3.4), the temperature-controlled medium outflow channel, and the temperature-controlled medium outflow hole (3.5) is 4.0 mm, and the outer diameter is 8.0 mm.

[0068] The temperature-controlled ultrasonic microreactor of this embodiment has a resonant frequency of 40.8 kHz and a maximum input power of 60 W.

[0069] Example 3

[0070] The process for recrystallizing ε-CL-20 using the ultrasonic microreactor of Example 1 was as follows: Acetone was used as the solvent, and γ-type CL-20 was used as the raw material. The CL-20 concentration was 500 g / L. The CL-20-acetone solution was used as the first material, and n-octane was used as the antisolvent. Two parallel-flow pumps were used to transport the two materials from the solvent storage tank and the antisolvent storage tank to the ultrasonic microreactor, respectively. In the single-layer suspended microreactor, the flow rate of the CL-20-acetone solution in the microchannel was 0.5 mL / min, the flow rate of n-octane was 3.0 mL / min, and the volume ratio of antisolvent to solvent was 6. The temperature of the temperature-controlled medium was 25°C, and the residence time of the mixed solution of the two materials in the microreactor was 24.2 s; the ultrasonic radiation frequency was 20 kHz, and the power was 30 W. The product was filtered at the slurry outlet and vacuum dried at 50°C. The product weight was recorded, and the recrystallization recovery rate was calculated to be 84%. The purity of the ε-CL-20 crystal form was calculated to be 92% using X-ray diffraction.

[0071] Example 4

[0072] The process for recrystallizing ε-CL-20 using the ultrasonic microreactor of Example 2 was similar to that of Example 3, except for changes in parameters such as the raw material crystal form, solvent, and antisolvent flow rate. Specifically, α-type CL-20 was used as the raw material, the ultrasonic radiation frequency was 40 kHz, the power was 20 W, the solvent flow rate was 0.25 mL / min, the antisolvent flow rate was 1.50 mL / min, and the material residence time was 6.0 s. The results showed a recrystallization recovery rate of 72% and an ε-CL-20 crystal form purity of 30%.

[0073] Example 5

[0074] The process for recrystallizing ε-CL-20 using the ultrasonic microreactor of Example 1 was similar to that of Example 3, except for changes in the raw material crystal form, the type of antisolvent, the ultrasonic power, and the temperature of the temperature-controlled medium. Specifically, a mixture of γ-type CL-20 and α-type CL-20 was used as the raw material, n-heptane as the antisolvent, the ultrasonic power was 40W, and the temperature of the temperature-controlled medium was 15℃. The results showed a recrystallization recovery rate of 95% and an ε-CL-20 crystal form purity of 95%.

[0075] Example 6

[0076] The process for recrystallizing ε-CL-20 using the ultrasonic microreactor of Example 1 was similar to that of Example 3, except for changes in the solvent type, CL-20 concentration, and antisolvent / solvent volume ratio. Specifically, the solvent type was ethyl acetate, the CL-20 concentration was 600 g / L, the solvent flow rate was 0.1 mL / min, the antisolvent flow rate was 1.5 mL / min, the solution residence time was 53.0 s, the ultrasonic radiation frequency was 20 kHz, and the power was 30 W. The results showed a recrystallization recovery rate of 97% and an ε-CL-20 crystal form purity of 96%.

[0077] Comparative Example 1

[0078] The process for recrystallizing ε-CL-20 using the ultrasonic microreactor of Example 1 was similar to that of Example 6, except without ultrasonic input. The results showed a recrystallization recovery rate of 32% and an ε-CL-20 crystal purity of 0%.

[0079] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. An ultrasonic microreaction system for continuous crystallization preparation of ε-CL-20, characterized in that, It includes a raw material supply end, an ultrasonic microreactor, and a product collection end connected in sequence; The ultrasonic microreactor includes a sandwich ultrasonic transducer and a microreactor with a hollow cavity, wherein the radiating surface of the sandwich ultrasonic transducer is rigidly connected to the bottom of the microreactor. The microreactor is equipped with at least one layer of suspended microreactor plate. The micro-reaction plate is equipped with microchannels and turbulence columns. The microchannels and turbulence columns inside the suspended micro-reaction plate are filled with a circulating temperature-controlled medium. The suspended microreactor plate is provided with a temperature-controlled medium inflow channel and a temperature-controlled medium outflow channel leading to the outside of the microreactor; The microchannel has a feed channel leading to the outside of the microreactor at its inlet end and a slurry discharge channel leading to the outside of the microreactor at its outlet end.

2. The ultrasonic microreactor system for continuous crystallization preparation of ε-CL-20 according to claim 1, characterized in that, The length of the microchannel is 5-100cm, and the hydraulic diameter is 0.5-5.0mm.

3. The ultrasonic microreactor system for continuous crystal transformation preparation of ε-CL-20 according to claim 1, characterized in that, The raw material supply end includes a material storage tank, which is connected to the inlet of the feed channel via a pumping device; The material storage tank includes a solvent storage tank and an antisolvent storage tank, and the feed channel includes a solvent feed channel and an antisolvent feed channel corresponding to the material storage tank.

4. The ultrasonic microreactor system for continuous crystal transformation preparation of ε-CL-20 according to claim 1, characterized in that, The sandwich ultrasonic transducer applies a frequency of 10-100kHz and a power of 0-200W.

5. A continuous crystallization method for preparing ε-CL-20 using ultrasonic microreactions, characterized in that, Includes the following steps: The ultrasonic microreactor system for preparing ε-CL-20 by continuous crystallization as described in any one of claims 1-4 is used to introduce antisolvent material and material containing CL-20 and solvent into the ultrasonic microreactor from the raw material supply end. The materials are mixed and reacted in the microchannel, and the prepared ε-CL-20 product is discharged to the product collection end through the slurry discharge channel.

6. The ultrasonic microreaction method for continuous crystal transformation preparation of ε-CL-20 according to claim 5, characterized in that, The CL-20 is one or a mixture of at least two of the following: γ-type CL-20, β-type CL-20, and α-type CL-20; The solvent is selected from at least one of acetone and ethyl acetate; The antisolvent is selected from at least one of toluene, n-octane, n-heptane, and petroleum ether.

7. The ultrasonic microreaction method for continuous crystal transformation preparation of ε-CL-20 according to claim 5, characterized in that, The reaction temperature is 15-40℃.

8. The ultrasonic microreaction method for continuous crystal transformation preparation of ε-CL-20 according to claim 5, characterized in that, The residence time of the antisolvent material, the material containing CL-20 and the solvent in the microchannel is 5-600 s.

9. The ultrasonic microreaction method for continuous crystal transformation preparation of ε-CL-20 according to claim 5, characterized in that, In the material containing CL-20 and solvent, the concentration of CL-20 is 200-800 g / L; The feed volume ratio of antisolvent to solvent is 0.5 to 30.

10. The ultrasonic microreaction method for continuous crystal transformation preparation of ε-CL-20 according to claim 5, characterized in that, The ε-CL-20 product is filtered and dried at the product collection end to obtain a high-purity ε-CL-20 product.

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