CN116813437B - H (H) 3 Preparation method and application of cobalt-based energetic complex constructed by BTI - Google Patents

Abstract

The invention discloses an H ₃ Preparation method and application of cobalt-based energetic complex constructed by BTI (binary-coded metal) and H ₃ The cobalt-based energetic complex constructed by BTI is characterized in that the chemical formula is Co ₄ (HBTI) ₄ (H ₂ O) ₈ Wherein, HBTI is 4, 5-ditetrazolyl imidazole with two protons removed. The H provided by the invention ₃ The preparation method of the BTI-based cobalt metal organic complex is simple to operate, good in thermal stability and novel cobalt-based energetic complex Co ₄ (HBTI) ₄ (H ₂ O) ₈ 4, 5-ditetrazolylimidazole (H) as nitrogen-rich heterocyclic ligand ₃ BTI) is an energetic ligand that is used in solid propellants to effectively promote the thermal decomposition of Ammonium Perchlorate (AP).

Description

Preparation method and application of cobalt-based energetic complex constructed with H3BTI

Technical field

The invention belongs to the technical field of complexes, and in particular relates to a preparation method and application of a cobalt-based energetic complex constructed with H ₃ BTI.

Background technique

In order to meet the growing military and civilian needs, it is of great significance to design and synthesize high-energy-density materials with excellent performance, safety and insensitivity. There is an inevitable inherent contradiction between the energy characteristics and safety performance of energetic materials, that is, the higher the energy, the worse the safety. At the end of the 19th century, elemental explosives such as trinitrotoluene (TNT) and RDX were successively synthesized and used. Later, it was discovered that the most effective way to increase energy is to introduce nitro groups. However, although the explosive power of polynitro energetic materials such as hexanitrohexaazaisowurtzitane (CL-20) is obviously increasing, the insensitivity is also increasing. It has risen sharply, but it is still not used in batches so far. An important reason is considering its safety. Energetic complexes are inorganic-organic hybrid functional materials that assemble metal ions and energetic ligands through coordination bonds. Their design and synthesis have become a research hotspot in the field of coordination chemistry.

When exploring the combustion catalytic performance of ammonium perchlorate (AP), a commonly used raw material in solid propellants, traditional catalyst metal oxides lack energetic groups, and the energy of the propellant will suffer a certain loss. Energetic complexes have the characteristics of both combustion catalysts and energetic additives. They can provide a certain amount of energy while maintaining good catalytic effect, effectively adjust the combustion performance of solid propellants, and achieve catalytic combustion of propellants. The nitrogen-rich compound 4,5-ditetrazolylimidazole has good energy properties and stability, and has the characteristics of high nitrogen content, dense structure and high thermal enthalpy, which can ensure high energy density materials when constructing energetic complexes. source of energy. In addition, compared with lead ions and mercury ions, cobalt ions are an environmentally friendly ion. Choosing non-toxic cobalt ions to construct green energetic complexes is expected to replace toxic and polluting explosives, and is the focus of research on energetic materials. Based on this, how to use nitrogen-rich ligands to develop stable new cobalt-based energetic catalysts and achieve catalytic combustion of the catalysts is the primary issue that needs to be solved.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the present invention proposes a preparation method and application of a cobalt-based energetic complex constructed with H ₃ BTI.

In order to achieve the above objects, the present invention provides the following technical solutions:

One of the technical solutions of the present invention is to provide a cobalt-based energetic complex constructed of H ₃ BTI, whose chemical formula is Co ₄ (HBTI) ₄ (H ₂ O) ₈ , wherein HBTI is a complex with two protons removed. 4,5 Ditetrazolylimidazole.

Furthermore, the crystal structure of the cobalt-based energetic complex belongs to the monoclinic crystal system, P2(1)/n space group, and the unit cell parameters are: α=90, β=102.517(14), and γ=90.

The smallest asymmetric unit of the cobalt-based energetic complex provided by the invention is a unique four-nuclear structure, which consists of two Co(II) ions, two HBTI ^2- ligands and four H ₂ O molecular composition. At the same time, Co(II) ions also have two different coordination modes. Specifically, on the equatorial plane, O1 in Co1 replaces the N3 atom of Co2. At the bottom of the octahedron, N18 atoms replace the O3 atom. Every two The Co(II) ions are connected by the ligand HBTI ^2- in the middle, and are connected in the coordination mode of μ ₂ ∶ ¹ ∶ ¹ ∶ ¹ ∶ ¹ to form [Co1-(μ ₂ '-HBTI)-Co2-(μ _2' -HBTI)-Co1] configuration, forming a centrally symmetrical ellipsoidal hollow four-core unit. This structural stability determines the stability of its chemical properties. Specifically, the cobalt-based energetic complex has good thermal stability. The present invention has verified that its decomposition temperature is greater than 200°C.

The second technical solution of the present invention is to provide a method for preparing the cobalt-based energetic complex constructed by H ₃ BTI, which includes the following steps: under closed conditions, combine the organic ligand H ₃ BTI with hexahydrate nitric acid Cobalt is added to water at a molar ratio of 1:4 for hydrothermal reaction, and the collected crystals are cobalt-based energetic complexes constructed of H ₃ BTI.

Further, the preparation method also includes adding concentrated nitric acid before the hydrothermal reaction; the volume ratio of the water to concentrated nitric acid is 6 mL:0.34 μL.

Furthermore, the hydrothermal reaction was carried out at 150°C for 72 hours.

Furthermore, after the hydrothermal reaction, through natural cooling or cooling to room temperature at a rate of 3°C/h, pink crystals can be obtained, which are cobalt-based energetic complexes constructed with H ₃ BTI. The cooling method and cooling rate have little impact on the product. A typical but non-limiting cooling method selected by the present invention is natural cooling to room temperature.

The third technical solution of the present invention is to also provide the application of the cobalt-based energetic complex constructed with H ₃ BTI as an energetic combustion catalyst.

The fourth technical solution of the present invention is to also provide the application of the energetic combustion catalyst in catalyzing the thermal decomposition of AP. During the catalytic process, the mass ratio of the energetic combustion catalyst to the AP is 1:3. The cobalt-based energetic complex provided by the invention can advance the thermal decomposition temperature of AP by about 25°C, and has good application prospects in catalyzing the thermal decomposition of AP.

Compared with the existing technology, the present invention has the following advantages and technical effects:

The present invention selects nitrogen-rich heterocyclic ligand 4,5-ditetrazolylimidazole (H ₃ BTI) as the energy ligand and non-toxic cobalt ions to construct a new green cobalt-based energetic complex Co ₄ (HBTI) ₄ ( H ₂ O) ₈ . H ₃ BTI with high nitrogen content ensures the energy source of high-energy-density materials when constructing new energetic complexes, and the rigid ligands further ensure the stability of the structure of the complex Co ₄ (HBTI) ₄ (H ₂ O) ₈ .

In the present invention, the energetic complex Co ₄ (HBTI) ₄ (H ₂ O) ₈ is used in the combustion decomposition of solid propellant AP. The high-nitrogen ligand H ₃ BTI realizes the high energy of the catalyst while maintaining good catalytic effect. Providing a certain amount of energy avoids the problem of propellant energy loss caused by traditional metal oxide catalysts, and can effectively promote the thermal decomposition of AP.

Description of the drawings

The drawings that form a part of this application are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an improper limitation of this application. In the attached picture:

Figure 1 is a coordination environment diagram of the metal center of the energetic complex prepared in Example 1 of the present invention;

Figure 2 is a three-dimensional supramolecular structure diagram of the energetic complex prepared in Example 1 of the present invention;

Figure 3 is a thermogravimetric diagram 3 (TG curve) of the energetic complex prepared in Example 1 of the present invention;

Figure 4 is the differential scanning volume (DSC curve) of the energetic complex prepared in Example 1 of the present invention;

Figure 5 is a DSC curve of the energetic complex catalyzed AP prepared in Example 1 of the present invention.

Detailed ways

Various exemplary embodiments of the invention will now be described in detail. This detailed description should not be construed as limitations of the invention, but rather as a more detailed description of certain aspects, features and embodiments of the invention.

It should be understood that the terms used in the present invention are only used to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges in the present invention, it should be understood that every intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or value intermediate within a stated range and any other stated value or value intermediate within a stated range is also included within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded from the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only the preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials in connection with which the documents relate. In the event of conflict with any incorporated document, the contents of this specification shall prevail.

It will be apparent to those skilled in the art that various modifications and changes can be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to the skilled person from the description of the invention. The specification and examples are intended to be illustrative only.

The words "includes", "includes", "has", "contains", etc. used in this article are all open terms, which mean including but not limited to.

Unless otherwise specified, the "room temperature" mentioned in the present invention is calculated as 25±2°C.

The raw materials used in the following examples of the present invention are all commercially available.

The preparation method of the H ₃ BTI-based cobalt metal organic complex proposed by the invention is simple to operate, has good thermal stability, and uses nitrogen-rich heterocyclic ligand 4,5-ditetrazolylimidazole (H ₃ BTI) as the energy compound. The new cobalt-based energetic complex Co ₄ (HBTI) ₄ (H ₂ O) ₈ constructed by the solid propellant can effectively promote the thermal decomposition of ammonium perchlorate (AP). The specific technical solutions are as follows:

The invention provides a cobalt-based energetic complex constructed of H ₃ BTI, the chemical formula of which is Co ₄ (HBTI) ₄ (H ₂ O) ₈ ; wherein HBTI is 4,5 ditetrazolylimidazole with two protons removed. .

Furthermore, the crystal structure of the cobalt-based energetic complex belongs to the monoclinic crystal system, P2(1)/n space group, and the unit cell parameters are: α=90, β=102.517(14), and γ=90. The smallest asymmetric unit in this cobalt-based energetic complex consists of two Co(II) ions, two HBTI ^2- ligands and four H ₂ O molecules, forming a unique tetranuclear structure, Co(II) The ions have two different coordination modes. Co1 and Co2 are both six-coordinated octahedral configurations, consisting of four nitrogen atoms of the HBTI ^2- ligand and two oxygen atoms of the water molecule. The difference is that in the equatorial plane On the top, O1 in Co1 replaces the N3 atom of Co2. At the bottom of the octahedron, the N18 atom replaces the O3 atom. Each two Co(II) ions are connected by the ligand HBTI ^2- in the middle, with μ _{2 ∶} ¹ ∶ η ^{The 1} ∶ ¹ ∶ ¹ coordination mode is connected to the [Co1-(μ ₂ '-HBTI)-Co2-(μ ₂ '-HBTI)-Co1] configuration, forming a centrally symmetrical ellipsoidal hollow quad-core unit.

The invention also provides a method for preparing the cobalt-based energetic complex constructed by H ₃ BTI, which includes the following steps: under closed conditions, combine the organic ligand H ₃ BTI and cobalt nitrate hexahydrate at a molar ratio of 1: 4 was added to water, concentrated nitric acid was added dropwise, and stirred at room temperature for 30 minutes. Then the mixture was put into a hydrothermal reactor for hydrothermal reaction, heated to 150°C and kept for three days, and filtered to obtain pink block crystals (the result The crystal can be obtained by natural cooling to room temperature, or it can be obtained by cooling to room temperature at a rate of 3°C/h, preferably naturally cooling to room temperature), washed with distilled water and dried in the air, and the obtained energetic complex crystal is Cobalt-based energetic complex constructed from H ₃ BTI. The volume ratio of water to concentrated nitric acid is 6L:0.34 μL.

The invention also provides an application of the cobalt-based energetic complex constructed with H ₃ BTI as an energetic combustion catalyst in catalyzing the thermal decomposition of AP.

The following examples serve as further explanations of the technical solutions of the present invention.

Example 1

Mix 1 mmol of the organic ligand 4,5-ditetrazolylimidazole (H ₃ BTI) and 4 mmol of Co(NO ₃ ) ₂ ·6 (H ₂ O) and add it to 6 mL of deionized water. Add 0.34 μL of concentrated nitric acid dropwise. Stir thoroughly at room temperature for 30 minutes, then put the mixture into a hydrothermal reaction kettle, raise the temperature to 150°C and keep it warm for 72 hours, then naturally cool to room temperature until the crystals are completely precipitated, and an energetic complex is obtained, recorded as Co ₄ (HBTI ) ₄ (H ₂ O) ₈ , where HBTI is 4,5 ditetrazolylimidazole with two protons removed.

An elemental analyzer was used to conduct elemental analysis on the energetic complex prepared in this example. Elemental analysis calculation results (%): C 20.26, H 16.89, N 47.28%; Experimental values: C 20.28, H 16.90, N 47.32%; IR (KBr, cm ^–1 ): 3428 (s), 3131 (s), 2861(s), 2680(w), 2361(w), 1611(s), 1568(s), 1487(m), 1243(w), 1037(w), 983(m), 880(m), 851(m), 700(w).

Structural characterization and catalytic performance testing:

1. Use X-ray single crystal diffraction to analyze the product prepared in this example on a Buruker SmartApexII CCD single crystal diffractometer, using Mo target, Kα radiation source (λ=0.71073nm), test temperature 293K; and use Olex2. Structural analysis.

The coordination environment diagram of the metal center of the energetic complex obtained by X-ray single crystal diffraction is shown in Figure 1. As can be seen from Figure 1, the six-coordinated Co1 and Co2 atoms are centered and connected by the ligand HBTI ^2- . The smallest asymmetric unit consists of two Co(II) ions, two HBTI ^2- ligands and four H ₂ O molecules, forming a unique four-core structure. The Co(II) ions have two different coordination modes. . Both Co1 and Co2 have a six-coordinated octahedral configuration, consisting of four nitrogen atoms of the HBTI ^2- ligand and two oxygen atoms of the water molecule. The difference is that on the equatorial plane, O1 in Co1 replaces Co2 N3 atom, at the bottom of the octahedron, N18 atom replaces the O3 atom, and each two Co(II) ions are connected by the ligand HBTI ^2- in the middle, coordinated with μ ₂ ∶η ¹ ∶η ¹ ∶η ¹ ∶η ¹ The modes are connected into the [Co1-(μ ₂ '-HBTI)-Co2-(μ ₂ '-HBTI)-Co1] configuration, forming a centrally symmetrical ellipsoidal hollow four-core unit.

The supramolecular structure of the energetic complex obtained by X-ray single crystal diffraction is shown in Figure 2. As can be seen from Figure 2, the dark gray balls represent C atoms and Co atoms, the light gray balls connected to them represent O and N atoms, and the white balls represent H atoms. The molecular weight of the energetic complex is 1184.48, the crystal belongs to the monoclinic system, P2(1)/n space group, and its unit cell parameters are: α=90, β=102.517(14), γ=90.

2. Conduct thermogravimetric and differential scanning calorimetry tests on the products prepared in this example. The test is performed on a NetzschSTA449C instrument and a CDR-4P thermal analyzer. The test conditions are room temperature to 800°C, and the temperature rise rate is 10°C·min ^{- 1} .

The thermogravimetry of the energetic complex prepared in this example is shown in Figure 3, and the differential scanning calorimetry figure 4 is shown. It can be seen from the TG curve that the energetic complex begins to lose weight at 230°C. DSC measures a gentle endothermic peak and a sharp exothermic peak. The temperature of the exothermic peak is 368°C. It can be seen from this that the decomposition temperature of the energetic complex prepared in this implementation is greater than 200°C, showing excellent thermal stability.

Application case testing

The energetic complex prepared in Example 1 is used as an energetic combustion catalyst to catalyze the thermal decomposition of AP. The specific method is: take 0.6 mg of the energetic complex prepared in Example 1, and then according to the mass ratio of the energetic complex to AP: Mix at a ratio of 1:3 and put into an α-Al ₂ O ₃ crucible, and heat to 500°C at a heating rate of 10°C/min at room temperature.

The combustion catalysis results are shown in Figure 5. In the figure, 1+AP represents the combustion catalysis of the mixture of energetic complex 1 prepared in Example 1 and ammonium perchlorate AP, exo represents the exothermic peak, and AP represents the combustion decomposition reaction of only ammonium perchlorate AP.

As can be seen from Figure 5, only the DSC curve of AP has one endothermic peak and two exothermic peaks: first, an endothermic peak appears at around 240°C, which is the crystal form transformation peak of AP, due to the perchlorate anion. Free rotation, the crystal transforms from the orthorhombic system to the cubic system; then the first exothermic peak appears at around 335°C, which is the low-temperature decomposition stage of AP. AP partially decomposes and transforms into porous material and releases heat; at 440°C A second exothermic peak appears around ℃, which is the high-temperature decomposition stage of AP, and the remaining solids are decomposed into volatile substances again. In the combustion catalytic reaction catalyzed by energetic complexes, the first exothermic peak appears at around 310°C, and the thermal decomposition temperature is 25°C earlier, indicating that the energetic complexes Co ₄ (HBTI) ₄ (H ₂ O) ₈ thermally decomposes AP It has good catalytic effect and shows potential as a combustion catalyst.

The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. All are covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (7)

1. H (H) ₃ The cobalt-based energetic complex constructed by BTI is characterized in that the chemical formula is Co ₄ (HBTI) ₄ (H ₂ O) ₈ Wherein, HBTI is 4, 5-ditetrazolyl imidazole with two protons removed.

2. H according to claim 1 ₃ The cobalt-based energetic complex constructed by BTI is characterized in that the cobalt-based energetic complex is of a monoclinic structure, P2 (1)/n space group is formed, and unit cell parameters are as follows: α=90, β= 102.517 (14), γ=90.

3. An H as claimed in claim 1 or claim 2 ₃ The preparation method of the cobalt-based energetic complex constructed by the BTI is characterized by comprising the following steps of: under closed conditions, the organic ligand H ₃ Adding BTI and cobalt nitrate hexahydrate into water according to the mol ratio of 1:4 to make hydrothermal reaction, collecting the obtained crystal ₃ Cobalt-based energetic complexes constructed by BTI.

4. A H according to claim 3 ₃ The preparation method of the cobalt-based energetic complex constructed by BTI is characterized by further comprising the step of adding concentrated nitric acid before hydrothermal reaction; the volume ratio of the water to the concentrated nitric acid is 6mL to 0.34 mu L.

5. H according to claim 3 or 4 ₃ The preparation method of the cobalt-based energetic complex constructed by BTI is characterized in that the hydrothermal reaction is carried out for 72 hours at 150 ℃.

6. An H as claimed in claim 1 or claim 2 ₃ The cobalt-based energetic complex constructed by BTI is applied as an energetic combustion catalyst.

7. Use of an energetic combustion catalyst in the catalysis of thermal decomposition of AP according to claim 6, wherein the mass ratio of the energetic combustion catalyst to the AP is 1:3.