CN-116440530-B - Micro-nano HMX micro-scale continuous flow fractional crystallization preparation method and system

CN116440530BCN 116440530 BCN116440530 BCN 116440530BCN-116440530-B

Abstract

The invention relates to a preparation method and a system for micro-nano HMX micro-scale continuous flow fractional crystallization. The method comprises the steps of (1) dissolving HMX in a solvent to form an HMX solution, mixing the solvent with an antisolvent to prepare a crystal transformation liquid, (2) flowing the HMX solution prepared in the step (1) and the antisolvent into a primary micro-mixed crystallization unit according to a required flow ratio to generate a mixed crystal HMX suspension with the mixed crystal granularity of 400nm-60 mu m, (3) flowing the mixed crystal HMX suspension flowing out of the primary micro-mixed crystallization unit and the crystal transformation liquid prepared in the step (1) into a secondary micro-mixed crystallization unit according to a required flow ratio, and performing secondary crystallization on the mixed crystal system to obtain the pure beta-HMX suspension with the grain size of microns. The micro-nano beta-HMX with high crystal transformation degree and high crystal form purity can be obtained by changing the mixing condition and the retention time in the secondary crystallization unit, and the continuous controllable preparation of the high-quality simple substance beta-HMX with smaller crystal size and high crystal form purity can be satisfied by a twice fractional crystallization mode.

Inventors

ZHU PENG
LIU JINBO
SHI JINYU
SHEN RUIQI
YE YINGHUA

Assignees

南京理工大学

Dates

Publication Date: 20260505
Application Date: 20230411

Claims (8)

1. The preparation method of the micro-nano HMX micro-scale continuous flow fractional crystallization is characterized by comprising the following steps of: Dissolving HMX in a solvent to form an HMX solution, and mixing the solvent and an antisolvent to prepare a crystal transformation liquid; Step (2), the HMX solution prepared in the step (1) and an antisolvent flow into a primary micro-mixed crystallization unit according to a required flow ratio to generate a mixed crystal HMX suspension with a mixed crystal granularity of 400nm-60 mu m; Step (3), the mixed crystal HMX suspension flowing out of the primary micro-mixed crystallization unit and the crystal transferring liquid prepared in the step (1) flow into a secondary micro-mixed crystallization unit according to the required flow ratio, and the mixed crystal system is subjected to secondary crystallization to obtain pure beta-HMX suspension with micron-sized crystal grains; The HMX solution and the antisolvent in the step (2) flow into a primary micro-mixed crystallization unit in a flow ratio of 1:1-20; The mixed crystal HMX suspension and the crystal transferring liquid in the step (3) flow into a secondary micro mixed crystallization unit according to the flow ratio of 1-10:1; The flow rate of the HMX solution and the antisolvent in the step (2) flowing into the primary micro-mixed crystallization unit ranges from 1 ml/min to 60 ml/L, and the flow rate of the mixed crystal HMX suspension and the crystal transformation liquid in the step (3) flowing into the secondary micro-mixed crystallization unit ranges from 1 ml/min to 60 ml/min.
2. The method of claim 1, wherein the anti-solvent is water and the solvent is dimethyl sulfoxide, N-dimethylformamide, acetone, or acetonitrile.
3. The method according to claim 2, wherein the concentration of HMX solution prepared in step (1) is 0.2g/ml or 0.4g/ml; The ratio of the solvent to the antisolvent for preparing the crystal transformation liquid in the step (1) is 1-10:1.
4. A method according to claim 3, wherein the crystallization temperature of the primary and secondary micro-hybrid crystallization units is 10 ℃ to 70 ℃.
5. The method of claim 4, wherein the primary micro-mixed crystallization unit and the secondary micro-mixed crystallization unit are coupled to a physical field type auxiliary crystallization unit, and the physical field of the physical field type auxiliary crystallization unit is any one or any several of sound, light, electricity, heat and magnetism.
6. A manufacturing system employed in the method of any one of claims 1-5, comprising a fluid drive unit, a primary micro-hybrid crystallization unit, a secondary micro-hybrid crystallization unit, a collection unit, and a connection assembly; the HMX solution and the antisolvent are respectively arranged in the respective fluid driving units, the outlets of the fluid driving units are connected with the inlet of the primary micro-mixed crystallization unit, the outlets of the primary micro-mixed crystallization unit are connected with the inlet of the secondary micro-mixed crystallization unit, the crystal conversion liquid is input into the inlet of the secondary micro-mixed crystallization unit through the fluid driving unit, and the outlets of the secondary micro-mixed crystallization unit are connected with the collecting unit.
7. The manufacturing system of claim 6, further comprising an auxiliary crystallization unit for auxiliary crystallization of the primary and secondary micro-hybrid crystallization units; the micro-mixing structure of the primary micro-mixing crystallization unit and the secondary micro-mixing crystallization unit is a two-dimensional structure Y-shaped, vortex-type or spiral-type or three-dimensional chaotic convection-type; The three-dimensional chaotic convection type micro-mixer consists of two chips carved with channels, wherein the shapes of the channels are square, round or triangular, the channels of the two chips are arranged in the horizontal direction to ensure that fluid can smoothly pass through, and the mixing effect of chaotic convection can be ensured to be generated in the mixer by the fluid in the vertical direction; The system also comprises an on-line monitoring system for acquiring the crystallization dynamics information of the explosive in real time.
8. The preparation system according to claim 6 or 7, wherein a plurality of primary micro-mixed crystallization units and secondary micro-mixed crystallization units are arranged in parallel, and the fluid driving units where the HMX solution, the antisolvent and the crystal transformation liquid are located are respectively provided with a plurality of outlets, which are respectively connected with inlets of the plurality of primary micro-mixed crystallization units and the secondary micro-mixed crystallization units arranged in parallel in a matching manner.

Description

Micro-nano HMX micro-scale continuous flow fractional crystallization preparation method and system Technical Field The invention belongs to the field of energetic materials, and particularly relates to a micro-nano HMX microscale continuous flow fractional crystallization preparation method and system. Background Explosives are important as a basic material for producing chemical explosions, both in military and civilian applications. Compared with the common size explosive, the micro-nano explosive has certain advantages and characteristics in the aspects of sensitivity selectivity, reaction critical dimension, combustion rate, detonation performance and the like, and has different basic physicochemical properties such as reaction activity, reaction heat transfer and mass transfer capability, thermal decomposition or thermal explosion and the like. HMX is an elementary substance explosive with optimal comprehensive performance at present, and four crystal forms of alpha-, beta-, gamma-, delta-exist between room temperature and the melting point of the HMX, wherein the beta-crystal form is the most stable at normal temperature and normal pressure and has the lowest mechanical sensitivity, and is a crystal form required by application. For the energetic compound with the same polymorphism, the design and regulation of the crystal morphology are of great significance for the safe and controllable energy release, and the transformation and control research of the polymorphism is also the key point of the research of the explosive crystal form. In recent years, the proposal of concepts such as green chemical industry, desktop type factories and the like has clarified that the miniaturization of chemical processes has gradually become a new mode of modern chemical development. The micro-reactor technology taking the micro-structural element as the main characteristic is based on the micro-channel to improve the mass transfer and heat transfer characteristics of the fluid, and lays a foundation for the enhanced efficient and safe implementation of the chemical process. Compared with the macro method, the micro channel reaction technology has small reagent amount and reduces the content of dangerous substances. Meanwhile, the microscale fluid flow has high specific surface area and high mass and heat transfer efficiency, which are unfavorable for hot spot formation, and provides a more temperature and controllable crystallization environment for the explosive crystal crystallization process, and has intrinsic safety. The regulation and control of the crystallization process of the elementary explosive crystals mainly depend on continuous flow. The viscous force between the inner and outer microfluid flowing in parallel in the continuous flow ensures that the fluid layer is easy to generate transverse momentum exchange with different degrees, thereby being beneficial to realizing the multi-state flow of the fluid under the microscale and controlling the crystallization environment. The continuous flow-based HMX recrystallization preparation needs to comprehensively consider the granularity and the crystal form of the HMX recrystallization preparation to obtain the high-quality micro-nano explosive with small particle size, narrow particle size distribution and stable crystal phase structure. However, a large number of experiments show that the HMX sample obtained by continuous flow recrystallization and primary crystallization is usually a mixed crystal system based on gamma-HMX, and it is difficult to directly obtain beta-HMX with higher purity. This phenomenon can be explained by the Ostwald phase transition rule and the spontaneous process gibbs free energy change rule, i.e. the crystallization process first precipitates not the stable crystalline form β -HMX but the metastable crystalline form γ -HMX. To obtain higher purity beta-HMX requires fractional crystallization to produce the desired crystalline form by secondary crystallization of HMX mixed with different crystalline forms. The traditional macroscopic solvent mediated crystal transformation process generally has longer retention time, so that the crystal has more sufficient growth time in the crystal transformation process, and the obtained HMX product is stable crystal form beta-, but has larger size, and can not meet the requirements of high-quality simple substance HMX on the crystal size and the crystal morphology. The mesostable crystal form gamma-HMX has shorter detention time in the process of transferring crystals in the micro-channel based on the micro-channel continuous flow technology, controls the growth of crystals, and can better maintain the control of primary crystallization on the size of micro-nano HMX crystals while realizing the transfer of crystals. Disclosure of Invention The invention aims to provide a micro-nano HMX micro-scale continuous flow fractional crystallization preparation method and system with both crystal size and c