Rare earth ferrocyanide / melamine derived multimetal complexed nitrogen heterocarbon burning rate catalyst

Abstract

The application discloses a rare earth ferrocyanide / melamine-derived multi-metal composite nitrogen heterocarbon burning rate catalyst, and the burning rate catalyst is prepared by the following steps: dropping a saturated aqueous solution of a soluble salt of a rare earth metal into a saturated aqueous solution of Na4[Fe(CN)6], and then performing solid-liquid separation, washing, drying, and obtaining a rare earth ferrocyanide after reaction; and then mixing the rare earth ferrocyanide with melamine by ball milling, and then performing calcination under the protection of inert gas. The preparation process of the burning rate catalyst is simple, the cost is low, and the preparation process is pollution-free. The melamine and the rare earth ferrocyanide are uniformly mixed by the ball milling method, then the transition metal Fe and the rare earth metal particles are uniformly loaded on the nitrogen heterocarbon material (g-C3N4) by high-temperature thermal condensation, and the synergistic effect of the multi-metals is used to improve the burning rate catalytic performance of the AP thermal decomposition.

Description

Technical Field

[0001] This invention belongs to the field of solid propellant technology, specifically relating to a rare earth ferrocyanate / melamine-derived multimetal composite nitrogen-carbon combustion rate catalyst. Background Technology

[0002] Solid propellants, as a crucial component propelling missiles and rocket engines, play a vital role in providing power for rocket and missile launches. Their composition and performance influence rocket speed and flight time. Currently, commonly used solid propellants can be broadly classified into two categories based on their composition and structure: double-base propellants and composite propellants. Double-base propellants can be further divided into modified and unmodified double-base propellants. Solid propellants mainly consist of binders, oxidants, plasticizers, curing agents, and burn rate modifiers. Burn rate modifiers are often categorized into burn rate catalysts and burn rate inhibitors based on their impact on the combustion rate of solid propellants. To adjust the combustion performance and improve the combustion rate of solid propellants, burn rate catalysts are often added. As a very important component of solid propellants, their function is often to participate in reactions through chemical methods, thereby improving the combustion performance of the propellant and meeting the launch requirements of different engines and propellants, thus satisfying the needs of modern spacecraft.

[0003] Ferrocyanates, namely Prussian blue and its analogues, are complexes with adjustable composition and open frameworks, exhibiting the typical physicochemical characteristics of large-framework materials. Prussian blue analogues often replace the iron and ferrous ions in Prussian blue with other metals to achieve higher specific surface area, stability, and chemical properties. In catalytic applications, metal compounds derived from Prussian blue and its analogues also possess excellent stability, selectivity, and precursor morphology, along with good electronic conductivity and sufficient catalytic active sites, making them a hot research topic across various fields.

[0004] Rare earth metals are a collective term for 17 metallic elements, consisting of the lanthanides, scandium, and yttrium. Many researchers have experimented with various metal combinations, and rare earth compounds have shown outstanding effects in catalyzing the combustion of dual-base propellants and reducing infrared decay of fuel gas. Furthermore, rare earth composite systems with other transition elements also exhibit superior catalytic performance in other fields. Due to their nearly identical outer electron configurations, rare earth elements share remarkably similar properties, making the diverse applications of rare earth resources a long-standing research hotspot.

[0005] Graphitic carbon nitride, or g-C3N4, is a special non-metallic semiconductor, an amorphous, artificially synthesized compound mainly formed by the stacking of two-dimensional CN sheets. As the most stable of the five allotropes of C3N4, g-C3N4 is insoluble in acids, alkalis, and common organic solvents, exhibiting excellent thermal and chemical stability. Furthermore, as a combustion rate catalyst, it possesses several significant advantages: simple preparation process, ease of operation, high cost-effectiveness, environmental friendliness, non-toxicity, and high-temperature resistance, demonstrating its promising application prospects. These advantages have long made g-C3N4 a focus of widespread attention in various reaction catalysis fields.

[0006] With the continuous deepening of research, many types of composite combustion rate catalysts have emerged in the field of solid propellants. Chi Huang et al. proposed a self-template strategy to design and synthesize cobalt-rich hollow spherical Prussian blue analogs through self-assembly process. Its spherical hollow structure can provide a large specific surface area and more active sites. The thermocatalytic performance of the catalyst in the AP system was studied, and the catalytic advantages and macroscopic kinetic behavior of the catalyst were tested (Zeyu Z, Chi H, et al. Hierarchical MOFs with Good Catalytic Properties and Structural Stability in Oxygen-Rich and High-Temperature Environments. Small, 2024, 2(19): 2309302). Zheng Jiahong et al. prepared a series of iron and manganese Prussian blue analog composite nitrogen-doped carbon nanosheet catalysts for the removal of Rhodamine B using a high-temperature carbonization method. The study showed that Prussian blue analogs were transformed into nitrogen-doped carbon materials with high specific surface area, high porosity and high nitrogen content after high-temperature calcination or inert gas carbonization, which is of great significance for improving the catalytic performance of the catalyst (Zheng Jiahong, Zheng Xin. Preparation and activation of FeMnO derived from nitrogen-doped graphite carbon supported Fe–Mn Prussian blue analog for the removal of Rhodamine B by persulfate. Journal of the Chinese Ceramic Society, 51(12):1-11). Danna Ma et al. reviewed the structure, properties, preparation and application of a series of g-C3N4 derivatives in the catalytic thermal decomposition of AP, and discussed in detail the enhanced catalytic mechanism of AP thermal decomposition (DNMa, XQWang, et al. Research Development on Graphitic Carbon Nitride and Enchanted Catalytic Activity on Ammonium Perchlorate. RSC Adv., 2021, 11(10): 5729-5740).

[0007] In summary, adding a burning rate catalyst, an important component of propellants, is a reasonable and efficient method to improve the combustion efficiency of propellants. According to previous studies, carbon materials have been proven to be excellent carriers for burning rate catalysts. Ferrocyanate, namely Prussian blue and its analogues, is a complex with an adjustable framework, exhibiting good stability and selectivity. Under high-temperature calcination, it can form a metal-intercalated nitrogen-carbon material through carbon condensation. Therefore, combining rare earth ferrocyanate with g-C3N4 to prepare novel composite burning rate catalysts is one of the potential development directions in the field of catalytic materials. Summary of the Invention

[0008] The purpose of this invention is to provide an environmentally friendly, convenient, and fast rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst with good catalytic performance.

[0009] To achieve the above objectives, the rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst provided by the present invention is a multimetallic composite nitrogen-carbon material with g-C3N4 as a carrier and Fe and rare earth metal particles supported by ball milling and mixing of rare earth ferrocyanate and melamine and calcination under inert gas protection. The rare earth ferrocyanate is selected from any one of Sm4[Fe(CN)6]3, Eu4[Fe(CN)6]3, Tb4[Fe(CN)6]3, and Dy4[Fe(CN)6]3. The mass ratio of rare earth ferrocyanate to melamine is 1:1 to 4, preferably 1:1.5 to 2.

[0010] The preparation method of the above-mentioned rare earth ferrocyanate is as follows: a saturated aqueous solution of a soluble salt of a rare earth metal is added dropwise to a saturated aqueous solution of Na4[Fe(CN)6]. After reacting at room temperature for 1.5 to 4 hours, the resulting suspension is subjected to solid-liquid separation. The solid is washed and dried to obtain rare earth ferrocyanate. The soluble salt of the rare earth metal is selected from any one of Sm(NO3)3·6H2O, Eu(NO3)3·6H2O, Tb(NO3)3·6H2O, and Dy(NO3)3·6H2O. The molar ratio of Na4[Fe(CN)6] to the rare earth metal element in the soluble salt of the rare earth metal is 1 to 2:1.

[0011] Furthermore, the ball milling frequency is 25–50 Hz, the forward rotation time is 5–30 min, the interval time is 5 min, the reverse rotation time is 5–30 min, and the cycle is repeated three times. Preferably, the ball milling frequency is 35–40 Hz, the forward rotation time is 10–15 min, the interval time is 5 min, the reverse rotation time is 10–15 min, and the cycle is repeated three times.

[0012] Furthermore, the calcination temperature is 300–800℃, the holding time is 1–8h, and the heating rate is 1–10℃ / min. Preferably, the calcination temperature is 450–550℃, the holding time is 4–6h, and the heating rate is 5–6℃ / min.

[0013] Furthermore, the aforementioned inert gas is argon.

[0014] The beneficial effects of this invention are as follows:

[0015] This invention mixes rare earth ferrocyanate and melamine in a specific ratio and calcines them under a certain calcination process. By introducing g-C3N4, which is prepared by high-temperature calcination of melamine, a rare earth ferrocyanate / melamine-derived multi-metal composite nitrogen-carbon material combustion rate catalyst is formed. This composite combustion rate catalyst exhibits excellent performance and is environmentally friendly. On the one hand, it leverages the carrier function of the g-C3N4 two-dimensional carbon material; on the other hand, through the synergistic effect between multiple metals, it achieves excellent catalytic effect on the thermal decomposition of azophosphorus compounds (AP). Attached Figure Description

[0016] Figure 1 The image shows a scanning electron microscope image of the combustion rate catalyst prepared in Example 1.

[0017] Figure 2 The differential scanning calorimetry (DSC) curves are those of the combustion rate catalyst prepared by adding 5 wt.% of AP in Examples 1-4 and pure AP.

[0018] Figure 3 Differential scanning calorimetry (DSC) curves are obtained by adding 5 wt.% of comparative examples 1 to 5 to AP, adding 5 wt.% g-C3N4 to AP, and using pure AP. Detailed Implementation

[0019] 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.

[0020] Example 1

[0021] 90.6 mg (0.02 mmol) of Tb(NO3)3·6H2O was added to 30 mL of water to obtain a saturated aqueous solution of Tb(NO3)3; 96.8 mg (0.02 mmol) of Na4[Fe(CN)6]·10H2O was added to 20 mL of water to obtain a saturated aqueous solution of Na4[Fe(CN)6]; then, the saturated aqueous solution of Tb(NO3)3 was added dropwise to the saturated aqueous solution of Na4[Fe(CN)6] using a dropper, and the mixture was stirred at 350 rpm for 2 h at room temperature to obtain a pale green suspension; the centrifuge speed was adjusted to [the desired speed]. The suspension was centrifuged at 10,000 rpm for 3 minutes to separate solids and liquids. The solid was washed three times with deionized water and once with anhydrous ethanol. The solid was then dried in a 60°C oven for 12 hours to obtain a light green powder, which is Tb4[Fe(CN)6]3. Melamine and the obtained light green powder Tb4[Fe(CN)6]3 were then mixed in a ball mill at a mass ratio of 3:2. The ball milling conditions were: ball milling frequency 35 Hz, forward rotation time 10 minutes, interval time 5 minutes, reverse rotation time 10 minutes, and repeated three times. The ball-milled mixed powder was then placed in a quartz boat, which was placed in a tube furnace. Argon gas was introduced for protection at a flow rate of 30 mL / min. The calcination temperature was 500℃, the holding time was 5 h, and the heating rate was 5℃ / min. After calcination, the product was removed from the tube furnace, yielding a terbium ferrocyanate / melamine-derived Tb-Fe composite nitrogen-carbon combustion rate catalyst, denoted as Tb-NCM / g-C3N4. Figure 1 It is evident that the obtained combustion rate catalyst has a hexagonal prism composite two-dimensional flocculent structure.

[0022] Example 2

[0023] In this embodiment, an equimolar amount of Sm(NO3)3·6H2O was used to replace Tb(NO3)3·6H2O in Example 1. The other steps were the same as in Example 1, and a Sm-Fe composite nitrogen-carbon combustion rate catalyst derived from samarium ferrocyanate / melamine was obtained, denoted as Sm-NCM / g-C3N4.

[0024] Example 3

[0025] In this embodiment, an equimolar amount of Eu(NO3)3·6H2O was used to replace Tb(NO3)3·6H2O in Example 1. The other steps were the same as in Example 1, and a Eu-Fe composite nitrogen-carbon combustion rate catalyst derived from europium ferrocyanide / melamine was obtained, denoted as Eu-NCM / g-C3N4.

[0026] Example 4

[0027] In this embodiment, Tb(NO3)3·6H2O in Example 1 was replaced with an equimolar amount of Dy(NO3)3·6H2O, and the other steps were the same as in Example 1, to obtain a Dy-Fe composite nitrogen-carbon combustion rate catalyst derived from dysprosium ferrocyanate / melamine, denoted as Dy-NCM / g-C3N4.

[0028] Comparative Example 1

[0029] 90.6 mg (0.02 mmol) of Tb(NO3)3·6H2O was added to 30 mL of water to obtain a saturated aqueous solution of Tb(NO3)3. 96.8 mg (0.02 mmol) of Na4[Fe(CN)6]·10H2O was added to 20 mL of water to obtain a saturated aqueous solution of Na4[Fe(CN)6]. The Tb(NO3)3 saturated aqueous solution was then added dropwise to the Na4[Fe(CN)6] saturated aqueous solution using a dropper. The reaction was carried out at room temperature with stirring at 350 rpm for 2 hours, yielding a pale green suspension. The centrifuge speed was adjusted to 10000 rpm, and the centrifugation time was... The resulting suspension was subjected to solid-liquid separation for 3 minutes. It was washed three times with deionized water and once with anhydrous ethanol. The resulting solid was dried in a 60℃ drying oven for 12 hours to obtain a light green powder, which is Tb4[Fe(CN)6]3. The obtained powder was then placed in a quartz boat, which was placed in a tube furnace and protected with argon gas at a flow rate of 30 mL / min. The calcination temperature was 500℃, the calcination holding time was 5 hours, and the heating rate was 5℃ / min. After calcination, the product was removed from the tube furnace to obtain the terbium ferrocyanate-derived Tb-Fe composite nitrogen-carbon combustion rate catalyst, denoted as Tb-NCM.

[0030] Comparative Example 2

[0031] In this comparative example, Tb(NO3)3·6H2O in Comparative Example 1 was replaced with an equimolar amount of Sm(NO3)3·6H2O, and the other steps were the same as in Comparative Example 1, to obtain a Sm-Fe composite nitrogen-carbon combustion rate catalyst derived from samarium ferrocyanide, denoted as Sm-NCM.

[0032] Comparative Example 3

[0033] In this comparative example, Tb(NO3)3·6H2O in Comparative Example 1 was replaced with an equimolar amount of Eu(NO3)3·6H2O, and the other steps were the same as in Comparative Example 1, to obtain the Eu-Fe composite nitrogen-carbon combustion rate catalyst derived from europium ferrocyanide, denoted as Eu-NCM.

[0034] Comparative Example 4

[0035] In this comparative example, Tb(NO3)3·6H2O in Comparative Example 1 was replaced with an equimolar amount of Dy(NO3)3·6H2O, and the other steps were the same as in Comparative Example 1, to obtain a Dy-Fe composite nitrogen-carbon combustion rate catalyst derived from dysprosium ferrocyanide, denoted as Dy-NCM.

[0036] Comparative Example 5

[0037] 50 mg of melamine was placed in a quartz boat, which was then placed in a tube furnace. Argon gas was introduced for protection at a flow rate of 30 mL / min. The calcination temperature was 500 °C, the calcination holding time was 5 h, and the heating rate was 5 °C / min. After calcination, the product was removed from the tube furnace to obtain graphitic carbon nitride, denoted as g-C3N4.

[0038] To demonstrate the beneficial effects of this invention, combustion catalytic performance tests were conducted by adding 5 wt.% of the combustion rate catalysts prepared in Examples 1-4 to AP, respectively. The results are shown in […]. Figure 2 Meanwhile, comparative experiments were conducted on the combustion catalytic performance of the combustion rate catalysts prepared in Comparative Examples 1–5, and the results are shown in [Figure 1]. Figure 3 .

[0039] from Figure 2 It can be seen that during the exothermic process of pure AP, the high-temperature decomposition peak temperature is relatively late, and the apparent heat release is relatively small. Under the same conditions, when 5 wt.% of the rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst from Examples 1-4 is added to the main component AP of the solid propellant, the peak temperature of AP in the high-temperature decomposition stage decreases from 402.3℃ to 297.9℃, 320.8℃, 319.8℃, and 314.7℃, respectively, and the apparent heat of decomposition of AP decreases from 679.81 kJ·g -1 They increased to 1601.05 kJ·g -1 1552.92 kJ·g -1 1507.89 kJ·g -1 1578.39 kJ·g -1 The increase was 921.24 kJ·g -1 873.11 kJ·g -1 828.08 kJ·g -1 898.58 kJ·g -1 Among them, the combustion rate catalyst Tb-NCM / g-C3N4 in Example 1 showed the highest degree of advancement in the high-temperature decomposition peak temperature of AP, the most concentrated heat release, and the greatest increase in the apparent heat of decomposition of AP. This indicates that the addition of 5 wt.% of the rare earth ferrocyanate / melamine-derived multi-metal composite nitrogen-carbon combustion rate catalyst from Examples 1-4 to AP has a significant catalytic effect on AP decomposition, advancing the AP decomposition peak temperature while simultaneously increasing the heat release significantly.

[0040] from Figure 3 It can be seen that, under the same conditions, the addition of 5 wt.% of rare earth ferrocyanate-derived polymetallic nitrogen-carbon combustion rate catalysts from Comparative Examples 1–4 and g-C3N4 from Comparative Example 5 to the main solid propellant component AP significantly reduced the decomposition peak temperature of AP. The high-temperature decomposition peak temperature of AP decreased from 402.3℃ to 311.5℃, 322.8℃, 317.4℃, and 320.7℃, respectively, and the apparent heat of decomposition of AP decreased from 679.81 kJ·g -1 They increased to 1493.40 kJ·g -1 1202.63 kJ·g -1 1351.83 kJ·g -1 1391.76 kJ·g -1 The increases were 813.59 kJ·g respectively. -1 522.82 kJ·g -1 672.02 kJ·g -1 711.95 kJ·g -1 The results were significantly better than those of pure AP, but compared with the catalytic effect of Tb-NCM / g-C3N4 in Example 1, its AP decomposition peak temperature was relatively later and the heat release was relatively lower.

[0041] In summary, comparing the catalytic effects of the rare earth ferrocyanate / melamine-derived multimetallic nitrogen-carbon combustion rate catalysts in Examples 1-4 with those in Comparative Examples 1-4 and g-C3N4 in Comparative Example 5 on AP, it was found that the terbium ferrocyanate / melamine-derived Tb-Fe composite nitrogen-carbon combustion rate catalyst had a sharper exothermic peak, a more concentrated exothermic effect, and a larger exothermic heat, as well as a greater advance in the high-temperature decomposition peak temperature. Therefore, the catalytic effect of adding 5 wt.% of the combustion rate catalysts prepared in Examples 1-4 to AP is significantly better than that of the composite combustion rate catalysts described in Comparative Examples 1-4 and g-C3N4 itself.

Claims

1. A rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst, characterized in that: The combustion rate catalyst is a multi-metal composite nitrogen-carbon material with g-C3N4 as a carrier and Fe and rare earth metal particles loaded on it, obtained by ball milling rare earth ferrocyanate and melamine and then calcining them under inert gas protection. The rare earth ferrocyanate is selected from any one of Sm4[Fe(CN)6]3, Eu4[Fe(CN)6]3, Tb4[Fe(CN)6]3, and Dy4[Fe(CN)6]3.

2. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 1, characterized in that: The mass ratio of the rare earth ferrocyanate to melamine is 1:1 to 4.

3. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 1, characterized in that: The mass ratio of the rare earth ferrocyanate to melamine is 1:1.5 to 2.

4. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to any one of claims 1 to 3, characterized in that: A saturated aqueous solution of a soluble salt of a rare earth metal was added dropwise to a saturated aqueous solution of Na4[Fe(CN)6]. After reacting at room temperature for 1.5–4 hours, the resulting suspension was subjected to solid-liquid separation. The solid was washed and dried to obtain rare earth ferrocyanide. The soluble salt of the rare earth metal is selected from any one of Sm(NO3)3·6H2O, Eu(NO3)3·6H2O, Tb(NO3)3·6H2O, and Dy(NO3)3·6H2O.

5. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 4, characterized in that: The molar ratio of Na4[Fe(CN)6] to the rare earth metal elements in the soluble salt of rare earth metals is 1 to 2:

1.

6. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 1, characterized in that: The ball milling frequency is 25-50Hz, the forward rotation time is 5-30 minutes, the interval time is 5 minutes, the reverse rotation time is 5-30 minutes, and the cycle is repeated three times.

7. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 1, characterized in that: The ball milling frequency is 35-40Hz, the forward rotation time is 10-15 minutes, the interval time is 5 minutes, the reverse rotation time is 10-15 minutes, and the cycle is repeated three times.

8. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 1, characterized in that: The calcination temperature is 300–800℃, the holding time is 1–8h, and the heating rate is 1–10℃ / min.

9. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 1, characterized in that: The calcination temperature is 450–550℃, the holding time is 4–6 h, and the heating rate is 5–6℃ / min.

10. The rare earth ferrocyanate / melamine-derived multimetallic composite nitrogen-carbon combustion rate catalyst according to claim 1, characterized in that: The inert gas is argon.

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