Tetrazolyl energetic coordination polymer filled ferrocene derivative composite burning rate catalyst

Abstract

This invention discloses a type of tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst. The composite combustion rate catalyst is prepared by filling the nanopores of an energetic coordination polymer synthesized with a tetrazolium compound as a ligand and manganese metal ions with a ferrocene derivative. The preparation method involves dissolving a tetrazolium compound and a manganese salt in a mixed solvent of methanol and acetone, and then adding the ferrocene derivative. The ferrocene derivative fills the nanopores of the energetic coordination polymer during the reaction of manganese metal ions and the ligand, thereby obtaining the composite combustion rate catalyst. The composite combustion rate catalyst of this invention exhibits good catalytic performance, significantly improving the migration problem of ferrocene-based combustion rate catalysts, and its preparation method is simple and easy to scale up.

Description

Technical Field

[0001] This invention belongs to the field of solid propellant technology, specifically relating to a series of tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite burning rate catalysts. Background Technology

[0002] Solid propellants are energetic composite materials with specific properties, serving as a crucial power source for advanced equipment such as missiles, rockets, and spacecraft. The main components of solid propellants are binders, oxidizers, combustion performance modifiers, plasticizers, stabilizers, antioxidants, and other functional additives. The level of their manufacturing process and technology directly reflects a country's technological strength in the aerospace and defense fields. Solid propellants can be broadly classified into dual-base propellants and composite propellants. Composite propellants are heterogeneous propellants where the components are physically mixed, exhibiting high specific impulse and energy density. Oxidizers are the main energetic component of solid propellants, and their thermal decomposition process directly affects the combustion performance of solid propellants. Commonly used oxidizers include ammonium perchlorate (AP), RDX, and HMX. AP is widely used in solid propellants due to its high enthalpy of formation, high density, and high oxygen content. Combustion modifiers are additives that adjust the combustion performance of solid propellants through physical or chemical methods. Although they are present in very small amounts (1 wt.%–5 wt.%) in solid propellants, they play a crucial role in the combustion process. Currently, widely used combustion rate catalysts in composite solid propellants include ferrocene and its derivatives, transition metal oxides, organometallic compounds, and nanomaterials. Among these, ferrocene-based combustion rate catalysts are widely used in solid propellants due to their superior performance.

[0003] Ferrocene is an organometallic compound with unique structure and properties, first synthesized by Kealy TJ and Pauson P.L. in 1951. This compound possesses a unique sandwich structure: two cyclopentadiene anions are bonded to an iron atom in parallel, forming a well-symmetrical molecular structure. This unique structure endows ferrocene with a series of distinctive chemical and physical properties, making it valuable for applications in multiple fields. Studies have shown that ferrocene and its derivatives decompose at high temperatures into iron oxide, which exhibits excellent catalytic performance and a significant catalytic effect on the combustion of solid propellants. Therefore, it is often used as a combustion rate catalyst in solid propellants. However, despite its excellent catalytic performance in solid propellants, ferrocene-based combustion rate catalysts still face some challenges in practical applications. Currently, commercially available ferrocene derivatives mainly include 2,2-bis(ethylferrocene)propane (Cat), n-octylferrocene (NOF), n-butylferrocene (NBF), and tert-butylferrocene (TBF). These ferrocene-based combustion rate catalysts exhibit volatility and migration issues within the propellant, leading to uneven distribution and reduced overall combustion performance. Furthermore, this migration can weaken the adhesion between the propellant grain and the liner, increasing safety risks during storage and use.

[0004] Energetic coordination compounds (ECCs) are a general term for compounds formed by the self-assembly of nitrogen-rich ligands and metal ions through coordination bonds. Energetic coordination polymers (ECPs) are coordination compounds with extended repeating coordination in one-dimensional, two-dimensional, or three-dimensional directions, based on ECCs. They possess high energy density, flammability and explosiveness, good catalytic performance, and a relatively stable three-dimensional network structure. Due to these properties, energetic coordination polymers are widely used in military and aerospace fields, such as solid propellants for missiles and rockets, explosives, and pyrotechnics, where their high energy release characteristics enable them to provide significant thrust and explosive power. Energetic metal-organic frameworks (EMOFs) are a class of porous crystalline materials with extended framework structures within ECPs. They are porous energetic materials with a periodic network structure formed by the self-assembly of metal ions or metal clusters (usually called nodes) and nitrogen-rich energetic ligands through coordination bonds. Its unique structure and exceptionally rich chemical diversity have led to its extensive research. It possesses a variety of excellent properties, such as ultra-high specific surface area, tunable pore size, abundant functional channels, and highly dispersed metal active sites. Furthermore, it exhibits high energy density and unique energetic properties, making it a promising candidate for applications in numerous fields.

[0005] Traditional catalysts, such as metal oxides, typically lack energetic groups, and while they increase the burning rate of propellants, they often reduce the total energy of the propellants. Energetic coordination polymers, however, can provide excellent catalytic effects through energetic ligands, thus offering significant potential to provide energy for solid propellants. Zhang Qi et al. synthesized a novel energetic coordination polymer using the tetrazolium-based organic energetic ligand 1H,1'H-[5,5'-bistetrazole]-1,1'-diol (H2BTO) and five transition metals (Mn(II), Co(II), Ni(II), Cu(II), Zn(II)). Studies showed that it possesses good thermal stability, good initiation performance, and safety performance, while also exhibiting efficient deflagration-to-detonation capability. Furthermore, the preparation process is safe, efficient, and low-polluting, making it suitable for use as an initiating explosive (Zhang Q, Chen D, Jing D, et al. Access to green primary explosives via constructing coordination polymers based on bis-tetrazole oxide and non-lead metals[J]. Green chemistry, 2019, 21(8):1947-1955.). Wang Tingwei et al. synthesized a polymer using 1H-tetrazole-5-formylhydrazine (TZCA) as a ligand and Cu... II Cu(TZCA)₂(ClO₄)₂, an energetic coordination compound with a metal center, has been shown to possess good thermal stability (T d =177℃), and is extremely sensitive to mechanical stimulation (IS=1J; FS=5N), tests show that it has excellent detonation ability (Wang T, Lu Z, Bu S, et al. Combination of nitrogen-rich skeleton and coordination group: Synthesis of a high-energy primary explosive based on 1H-tetrazole-5-carbohydrazide[J]. Defense Technology,2024,31:271-277.). Zhong et al. synthesized a dual-ligand energetic complex [Cu(MIM)2(AIM)2](DCA)2 containing both ligands 1-methylimidazolium (MIM) and 1-allylimidazolium (AIM). DSC test results show that it has excellent catalytic effect on ammonium perchlorate (AP). It advances the high-temperature decomposition peak temperature of AP by 88.8℃ and increases the heat release by 1678 J·g. -1 The activation energy for decomposition decreased by 47.1 kJ·mol⁻¹ -1(Zhong Ye, Li Ying, Wu Ruiqiang, et al. Synthesis, structure and catalytic effect of energetic complex [Cu(MIM)2(AIM)2](DCA)2 on AP thermal decomposition [J]. Energetic Materials, 2021, 29(6):501-508.). Mi Zhiyuan et al. disclosed a ZIF-67 filled ferrocene derivative nanocomposite combustion rate catalyst (CN115582145A) and a ZIF-8 composite ferrocene nanocomposite combustion rate catalyst (CN115739185A). These two patents confine ferrocene derivatives in ZIFs nanoscale channels, which greatly reduces the migration of ferrocene combustion rate catalysts and effectively solves the problem of easy migration of ferrocene combustion rate catalysts. Summary of the Invention

[0006] To address the migration problem of ferrocene-based burning rate catalysts while simultaneously improving the overall energy level of solid propellants, this invention provides a series of tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite burning rate catalysts that are simple to prepare and can be mass-produced. These catalysts exhibit excellent catalytic activity and significantly reduce the migration of ferrocene-based burning rate catalysts during long-term storage of solid propellants. The material is produced by filling ferrocene derivatives into the nanopores of the energetic coordination polymer during its synthesis, thereby reducing the migration problem of ferrocene-based burning rate catalysts. Simultaneously, the high energy density of the energetic coordination polymer itself is utilized to improve the overall energy level of the solid propellant. Furthermore, during the combustion and decomposition of AP, the synergistic catalytic effect of the bimetallic components in the ferrocene derivative and energetic coordination polymer enhances the combustion catalytic effect on the thermal decomposition of AP.

[0007] To achieve the above objectives, the tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst provided by the present invention is a ferrocene derivative filled into the nanopores of an energetic coordination polymer with manganese metal ions and tetrazolium compounds as ligands.

[0008] The above-mentioned tetrazolium compounds are selected from one of 1H-tetrazole (Tzl) and 5-aminotetrazole (5-Atz).

[0009] The ferrocene derivatives mentioned above are selected from any one of catoxine (Cat), n-butylferrocene (NBF), ethylferrocene (EF), and 1,1'-diethylferrocene (DEF).

[0010] In the above-mentioned composite combustion rate catalyst, the mass ratio of ferrocene derivative to energetic coordination polymer is 0.08 to 0.14:1.

[0011] The preparation method of the tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst of the present invention is as follows: Tetrazolium compounds and ferrocene derivatives are dissolved in a mixed solvent of methanol and acetone to obtain solution A; manganese perchlorate is dissolved in a mixed solvent of methanol and acetone to obtain solution B; then, under stirring conditions, solution B is added dropwise to solution A, and the pH is adjusted to 7-8 with triethylamine. The reaction is stirred at room temperature for 8-12 hours. The resulting precipitate is washed with anhydrous diethyl ether by centrifugation until colorless, and then dried under vacuum to obtain the tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst.

[0012] In the above preparation method, the preferred molar ratio of manganese perchlorate to triazole compounds and ferrocene derivatives is 1:3 to 6:3 to 6.

[0013] In the above preparation method, the volume ratio of methanol to acetone in the mixed solvent is preferably 0.5 to 1.5:1.

[0014] In the above preparation method, the centrifugation speed is preferably 5000-12000 rpm and the centrifugation time is 1-10 min.

[0015] In the above preparation method, the vacuum drying temperature is preferably 50-80℃ and the time is 5-10h.

[0016] The beneficial effects of this invention are as follows:

[0017] 1. This invention fills ferrocene derivatives into the nanopores of an energetic coordination polymer. The confinement effect of these nanopores stably confines the ferrocene derivatives within the pores. Furthermore, the synthesized energetic coordination polymer uses high-nitrogen ligands, which inherently possess high energy density, resulting in a high-energy-level composite burning rate catalyst, thereby improving the overall energy level of the solid propellant. Simultaneously, the ferrocene derivatives and the bimetallic components in the energetic coordination polymer exhibit a strong synergistic catalytic effect, significantly enhancing their catalytic performance. Moreover, the stable confinement of the ferrocene derivatives within the pores greatly reduces their migration during long-term storage of the solid propellant, effectively solving the problem of easy migration of ferrocene-based burning rate catalysts in propellants. 2. This invention is simple to operate, yields a high-yield composite burning rate catalyst, and can be mass-produced. It can obtain low-migration ferrocene-based burning rate catalysts under simple processing methods, with a filling rate between 8 wt.% and 14 wt.%. This composite material has the advantages of low migration, large specific surface area, and good catalytic effect. Attached Figure Description

[0018] Figure 1 This is a field emission transmission electron microscope image of the composite combustion rate catalyst prepared in Example 1.

[0019] Figure 2 This is a field emission transmission electron microscope image of the composite combustion rate catalyst prepared in Example 2.

[0020] Figure 3 The results are DSC test results of AP, the composite combustion rate catalyst prepared by adding 5 wt.% of Examples 1-2 to AP, the energetic coordination polymer prepared by Comparative Examples 1-2, and catoxine.

[0021] Figure 4 The results are DSC analysis of the composite combustion rate catalysts prepared in Examples 3-4 and AP with 5 wt.% added to each of Comparative Examples 1-2, the energetic coordination polymers prepared in Comparative Examples 1-2, and n-butylferrocene.

[0022] Figure 5 The results are DSC test results of the composite combustion rate catalyst prepared in Examples 5-6 and AP with 5 wt.% added to each of Comparative Examples 1-2, the energetic coordination polymer prepared in Comparative Examples 1-2, and ethyl ferrocene.

[0023] Figure 6 The results are DSC analysis of the composite combustion rate catalysts prepared in Examples 7-8 and AP with 5 wt.% added to each of Comparative Examples 1-2, the energetic coordination polymers prepared in Comparative Examples 1-2, and 1,1'-diethylferrocene.

[0024] Figure 7 The results are the 24-hour isothermal thermogravimetric analysis results of the composite combustion rate catalysts prepared by Katoxin and Examples 2, 4, 6, and 8.

[0025] Figure 8 These are images from the Katoxin migration test.

[0026] Figure 9 These are images of the migration test of the composite combustion rate catalyst prepared in Example 2.

[0027] Figure 10 These are images of the migration test of the composite combustion rate catalyst prepared in Example 3. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0029] Example 1

[0030] 280.2 mg (4 mmol) of 1H-tetrazole and 1128.8 mg (4 mmol) of captocillin were added to 40 mL of a 1:1 mixture of methanol and acetone and dissolved by stirring at 25 °C. This solution is recorded as solution A. Then, 361.9 mg (1 mmol) of Mn(ClO4)2·6H2O was added to 20 mL of a 1:1 mixture of methanol and acetone and dissolved by stirring at 25 °C. This solution is recorded as solution B. Solution A was placed on a magnetic stirrer and stirred at 600 rpm. -1 Solution B was slowly added dropwise to solution A, and the pH of the solution was adjusted to 7-8 with triethylamine. The mixture was stirred at 25°C for 12 hours. After the reaction, the solution was washed with anhydrous diethyl ether by centrifugation at 8000 rpm for 4 minutes each time, until the supernatant was completely colorless and transparent. The grayish-white solid precipitate was then dried in a vacuum drying oven at 70°C for 6 hours, ground, and collected to obtain the grayish-white MnTzl energetic coordination polymer-filled captosine composite combustion rate catalyst (see...). Figure 1 ), denoted as Cat@MnTzl.

[0031] Example 2

[0032] 340.3 mg (4 mmol) of 5-aminotetrazolium and 1128.8 mg (4 mmol) of captocillin were added to 40 mL of a 1:1 mixture of methanol and acetone and dissolved by stirring at 25 °C. This solution is recorded as solution A. Then, 361.9 mg (1 mmol) of Mn(ClO4)2·6H2O was added to 20 mL of a 1:1 mixture of methanol and acetone and dissolved by stirring at 25 °C. This solution is recorded as solution B. Solution A was placed on a magnetic stirrer and stirred at 600 rpm. -1 Solution B was slowly added dropwise to solution A, and the pH of the solution was adjusted to 7-8 with triethylamine. The mixture was stirred at 25°C for 12 hours. After the reaction, the solution was washed with anhydrous diethyl ether by centrifugation at 8000 rpm for 4 minutes each time, until the supernatant was completely colorless and transparent. The grayish-white solid precipitate was then dried in a vacuum drying oven at 70°C for 6 hours, ground, and collected to obtain the grayish-white Mn5-ATZ energetic coordination polymer-filled captosine composite combustion rate catalyst (see...). Figure 2 ), denoted as Cat@Mn5-ATZ.

[0033] Example 3

[0034] In this embodiment, equimolar n-butylferrocene was used to replace catoxine in Example 1, and the other steps were the same as in Example 1, resulting in a grayish-white MnTzl energetic coordination polymer-filled n-butylferrocene composite combustion rate catalyst, denoted as NBF@MnTzl.

[0035] Example 4

[0036] In this embodiment, equimolar n-butylferrocene was used to replace catoxine in Example 2, and the other steps were the same as in Example 2, resulting in a grayish-white Mn5-ATZ energetic coordination polymer-filled n-butylferrocene composite combustion rate catalyst, denoted as NBF@Mn5-ATZ.

[0037] Example 5

[0038] In this embodiment, equimolar ethyl ferrocene was used to replace catoxine in Example 1, and the other steps were the same as in Example 1, resulting in a grayish-white MnTzl energetic coordination polymer-filled n-butyl ferrocene composite combustion rate catalyst, denoted as EF@MnTzl.

[0039] Example 6

[0040] In this embodiment, equimolar ethyl ferrocene was used to replace catoxine in Example 2, and the other steps were the same as in Example 2, resulting in a grayish-white Mn5-ATZ energetic coordination polymer-filled n-butyl ferrocene composite combustion rate catalyst, denoted as EF@Mn5-ATZ.

[0041] Example 7

[0042] In this embodiment, equimolar 1,1'-diethylferrocene was used to replace catoxine in Example 1, and the other steps were the same as in Example 1, to obtain a grayish-white MnTzl energetic coordination polymer-filled n-butylferrocene composite combustion rate catalyst, denoted as DEF@MnTzl.

[0043] Example 8

[0044] In this embodiment, equimolar 1,1'-diethylferrocene was used to replace catoxine in Example 2, and the other steps were the same as in Example 2, to obtain a grayish-white Mn5-ATZ energetic coordination polymer-filled n-butylferrocene composite combustion rate catalyst, denoted as DEF@Mn5-ATZ.

[0045] Comparative Example 1

[0046] In this comparative example, 280.2 mg (4 mmol) of 1H-tetrazole was added to 30 mL of methanol and dissolved by stirring at 25 °C; this solution was recorded as solution A. Then, 361.9 mg (1 mmol) of Mn(ClO4)2·6H2O was added to 30 mL of methanol and dissolved by stirring at 25 °C; this solution was recorded as solution B. Solution A was placed on a magnetic stirrer and stirred at 600 rpm. -1Solution B was slowly added dropwise to solution A, and the pH of the solution was adjusted to 7-8 with triethylamine. The mixture was stirred at 25°C for 12 hours. After the reaction was complete, the mixture was washed with methanol by centrifugation at 10,000 rpm for 3 minutes each time, until the supernatant was completely colorless and transparent. The brown solid precipitate was then dried in a vacuum drying oven at 70°C for 6 hours. The resulting grayish-white energetic coordination polymer was collected by grinding and denoted as MnTzl.

[0047] Comparative Example 2

[0048] In this comparative example, 1H-tetrazole in Comparative Example 1 was replaced with an equimolar amount of 5-aminotetrazole, and the other steps were the same as in Comparative Example 1. The resulting grayish-white energetic coordination polymer was denoted as Mn5-ATZ.

[0049] The combustion catalytic performance of AP was analyzed in the materials obtained in Examples 1-8 and Comparative Examples 1-2, respectively. The results are shown in the figure. Figures 3-6 Compared to pure AP, the addition of energetic coordination polymers from Comparative Examples 1-2 or composite combustion rate catalysts from Examples 1-8 reduced the high-temperature decomposition peak temperature to 285.5-304.8℃ and increased the exothermic reaction to 1355.96-1788.41 J·g. -1 The composite combustion rate catalysts of ferrocene derivatives exhibited good combustion catalytic performance for the thermal decomposition of AP. Comparison of the DSC test curves of AP with those of ferrocene derivatives revealed that the composite combustion rate catalysts of Examples 1-8 showed higher catalytic effects on AP than the ferrocene derivatives themselves. Not only was the heat of combustion increased to a certain extent, but the decomposition peak temperature also shifted significantly to the left, and the exothermic range became more concentrated. This indicates that the composite of ferrocene derivatives with energetic coordination polymers helps to enhance their combustion catalytic activity. Furthermore, Example 2 showed the highest relative catalytic activity, advancing the high-temperature decomposition peak of AP by 116.7℃ and increasing the heat of combustion of AP by approximately 2.52 times (T). HTD =285.6℃, △H=1713.45J / g).

[0050] In addition, a 24-hour isothermal thermogravimetric analysis (TGA) was conducted on the catochine and the composite combustion rate catalysts prepared in Examples 2, 4, 6, and 8 at 70°C. The test results are as follows: Figure 7 As shown, pure captosine experienced significant weight loss after being kept at 70°C for 24 hours, losing approximately 4.3 wt.% of its mass. Under the same conditions, the weight loss of the composite combustion rate catalysts prepared in Examples 2, 4, 6, and 8 was almost negligible, thus demonstrating that the composite combustion rate catalyst of this invention possesses better anti-volatilization properties compared to ferrocene-based combustion rate catalysts. This also indirectly proves that the composite combustion rate catalyst of this invention has excellent anti-migration capabilities. Figure 8 , Figure 9 and Figure 10The figures show the migration resistance test results for catoroxane, the composite combustion rate catalysts prepared in Examples 2 and 3, respectively, after storage at 50°C for one month. As can be seen from the figures, catoroxane underwent significant migration, migrating by 4.0 mm, 7.1 mm, 9.9 mm, and 11.1 mm in the first, second, third, and fourth weeks, respectively; while the composite combustion rate catalysts prepared in Examples 2 and 3 showed almost no migration. The results indicate that filling the pores of the tetrazolium-based energetic coordination polymer with ferrocene derivatives can significantly improve the volatility resistance and migration resistance of ferrocene-based combustion rate catalysts, demonstrating excellent anti-migration and anti-volatilization potential.

[0051] The experimental results above show that, after being filled with ferrocene derivatives, the composite burning rate catalysts of Examples 1-8 all exhibit improved performance compared to the energetic coordination polymers of Comparative Examples 1-2, such as a forward peak temperature or increased heat release. While the composite burning rate catalyst of Example 3 shows a slightly lower catalytic effect on AP compared to the energetic coordination polymer of Comparative Example 1, its migration properties are significantly reduced due to the addition of n-butylferrocene, demonstrating extremely strong anti-migration properties compared to n-butylferrocene itself in practical applications.

Claims

1. A type of tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst, characterized in that: The composite combustion rate catalyst is made by filling ferrocene derivatives into the nanopores of an energetic coordination polymer with manganese metal ions and tetrazolium compounds as ligands; the mass ratio of ferrocene derivatives to energetic coordination polymers in the composite combustion rate catalyst is 0.08 to 0.14:

1.

2. The tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst according to claim 1, characterized in that: The tetrazolium compound is selected from either 1H-tetrazole or 5-aminotetrazole.

3. The tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst according to claim 1, characterized in that: The ferrocene derivative is selected from any one of catoxine, n-butylferrocene, ethylferrocene, and 1,1'-diethylferrocene.

4. The tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst according to any one of claims 1 to 3, characterized in that... The composite combustion rate catalyst was prepared by the following method: Tetraazole compounds and ferrocene derivatives were dissolved in a mixed solvent of methanol and acetone to obtain solution A; manganese perchlorate was dissolved in a mixed solvent of methanol and acetone to obtain solution B; then, under stirring conditions, solution B was added dropwise to solution A, and the pH was adjusted to 7-8 with triethylamine. The reaction was stirred at room temperature for 8-12 h, and the resulting precipitate was washed with anhydrous diethyl ether by centrifugation until colorless and dried under vacuum to obtain a tetraazole-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst.

5. The tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst according to claim 4, characterized in that: The molar ratio of manganese perchlorate to tetrazolium compounds and ferrocene derivatives is 1:3 to 6:3 to 6.

6. The tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst according to claim 4, characterized in that: The volume ratio of methanol to acetone in the mixed solvent is 0.5 to 1.5:

1.

7. The tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst according to claim 4, characterized in that: The centrifugation speed is 5000-12000 rpm, and the centrifugation time is 1-10 min.

8. The tetrazolium-based energetic coordination polymer-filled ferrocene derivative composite combustion rate catalyst according to claim 4, characterized in that: The vacuum drying temperature is 50–80 °C and the time is 5–10 h.

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