Transition metal-nitrogen carbon catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of solid propellants, and particularly discloses a transition metal-nitrogen carbon catalyst and a preparation method and application thereof.The element composition of the transition metal-nitrogen carbon catalyst is M-CN, M is transition metal, and the transition metal is dispersed and loaded on a nitrogen-doped carbon carrier; the particle size of the transition metal-nitrogen carbon catalyst is 3-5 [mu] m; the transition metal M is selected from one or more of iron, cobalt, nickel, copper, lead, chromium and manganese; the preparation method comprises the following steps: by taking transition metal salt, 1, 10-phenanthroline and activated carbon as raw materials, carrying out oil bath reaction under an organic solvent system to obtain a catalyst precursor; and carrying out high-temperature carbonization reaction on the catalyst precursor in an inert atmosphere to finally obtain the transition metal-nitrogen carbon catalyst. The catalyst disclosed by the invention has remarkable ammonium perchlorate pyrolysis catalytic performance, and after the catalyst is blended with the catalyst, the pyrolysis temperature of ammonium perchlorate is remarkably reduced, and the heat release amount is also remarkably increased.

Description

Technical Field

[0001] This invention relates to the field of solid propellant technology, and more specifically to a transition metal-nitrogen-carbon catalyst, its preparation method, and its application. Background Technology

[0002] Composite solid propellants are widely used as an important power source in missile weapons and aerospace launch vehicles. They release chemical energy through combustion and then convert it into kinetic energy. Combustion performance directly affects the ballistic performance of solid rocket engines and is one of the most important performance indicators of solid propellants.

[0003] Solid propellants are mainly composed of oxidizers, binders, plasticizers, metallic fuels, and other additives. Among these, oxidizers, as the oxygen source for propellant combustion, constitute a significant proportion of the propellant formulation, and their thermal decomposition process has a substantial impact on the propellant's combustion behavior and energy release. Among various oxidizers, ammonium perchlorate (AP) is the most widely used oxidizer in solid propellants to date due to its advantages such as high effective oxygen content, high density, large gas generation, and low cost. However, AP thermal decomposition suffers from problems such as high pyrolysis temperature, low heat release, and uneven heat release. To meet the performance requirements of modern defense construction for solid propellants and to effectively control the combustion performance of AP-based solid propellants, it is essential to improve the thermal decomposition performance of AP.

[0004] Adding a combustion catalyst is one of the most effective ways to improve the thermal decomposition performance of AP. Common combustion catalysts include elemental metals, metal oxides, metal composite oxides, and carbon-based composite catalysts. However, they usually have problems such as easy agglomeration and oxidation, which leads to reduced catalytic activity, or complex preparation processes and high costs, making it difficult to meet the actual needs of engineering applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and to provide a transition metal-nitrogen-carbon catalyst, its preparation method and application.

[0006] The technical problem solved by this invention is achieved by the following technical solution. One aspect of this invention provides a transition metal-nitrogen-carbon catalyst, wherein the elemental composition of the transition metal-nitrogen-carbon catalyst is M-CN, where M is a transition metal, CN is a nitrogen-doped carbon support, and the transition metal is dispersed and supported on the nitrogen-doped carbon support (the transition metal is highly dispersed and supported on the surface of the nitrogen-doped carbon support or embedded within it; the catalyst exhibits an irregular, multi-folded cluster morphology in its microstructure); the particle size of the transition metal-nitrogen-carbon catalyst is 3~5 μm.

[0007] Furthermore, the aforementioned transition metal M is selected from one or more of iron, cobalt, nickel, copper, lead, chromium, and manganese.

[0008] The second aspect of the present invention provides a method for preparing a transition metal-nitrogen-carbon catalyst, wherein a catalyst precursor is obtained by first performing an oil bath reaction in an organic solvent system using a transition metal salt, 1,10-phenanthroline and activated carbon as raw materials; the catalyst precursor is then subjected to a high-temperature carbonization reaction in an inert atmosphere to finally obtain the transition metal-nitrogen-carbon catalyst.

[0009] Furthermore, the preparation method of the present invention includes the following steps: S1. A certain amount of transition metal salt and 1,10-phenanthroline are dispersed in an organic solvent, ultrasonicated to make them evenly dispersed, transferred to a constant temperature oil bath, and stirred at the same time during the heat preservation process to obtain the first mixture. S2. Add a certain amount of activated carbon to the first mixture, continue stirring and keep warm for the specified time, then turn off the heating and let it cool naturally. S3. The product obtained by alternating filtration and washing with water and alcohol was dried and ground to obtain the catalyst precursor; S4. The catalyst precursor undergoes a high-temperature carbonization reaction under N2 or Ar to obtain the transition metal-nitrogen-carbon catalyst.

[0010] Furthermore, in step S1 above: The transition metal salts include one or more of hydrochloride, nitrate, acetate, sulfate, and ferrocene; The organic solvent is anhydrous ethanol and / or N,N-dimethylformamide; The molar ratio of transition metal salt to 1,10-phenanthroline is 1:3 to 1:5.

[0011] Furthermore, the stirring time in step S1 is 20~30 min; the heat preservation temperature range in steps S1 and S2 is 50℃~70℃; the stirring rate is 200~300 r / min; and the stirring and heat preservation time in step S2 is 8~12 h.

[0012] Furthermore, in step S4 above, N2 or Ar is introduced for at least 30 minutes before high-temperature activation to purge the air; the programmed heating rate for high-temperature activation is 2℃ / min to 10℃ / min, the holding temperature is controlled at 400℃ to 800℃, and the holding time is controlled at 2h to 4h.

[0013] A third aspect of the invention provides the application of a transition metal-nitrogen-carbon catalyst in a propellant.

[0014] The present invention has the following beneficial effects: The transition metal-nitrogen-carbon catalyst of the present invention has the characteristics of high efficiency with small amount and excellent catalytic performance. Furthermore, the preparation method of this invention has significant versatility. That is, by selecting different transition metal salts during the feeding process, transition metal-nitrogen-carbon catalysts with different transition metal supports can be obtained.

[0015] The transition metal-nitrogen-carbon catalyst obtained by this invention has a simple preparation process, high yield, and easy-to-control reaction conditions. Some transition metal-nitrogen-carbon catalysts exhibit good catalytic performance in AP thermal decomposition and have high application value as AP-based solid propellant combustion catalysts. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 For pure AP and Pb / Cu-CN under the same ignition conditions 600 -AP(Pb / Cu-CN 600 High-speed photographic comparison of laser ignition of propellant mixed powders with a content of 10 wt%), where (a1)-(d1) are high-speed photographic images at different time points in the pure AP combustion process; Figures (a2)-(d2) are Pb / Cu-CN 600 -High-speed photographs of AP at corresponding time points during the pure AP combustion process; Figure 2 This is a schematic diagram of the preparation process of the transition metal-nitrogen-carbon catalyst in an embodiment of the present invention; Figure 3 The images show SEM images of the transition metal-nitrogen-carbon catalyst Pb / Cu-CN prepared in Examples 1, 2, and 3 of this invention. Figure 4 The XRD patterns are of the transition metal-nitrogen-carbon catalyst Pb / Cu-CN prepared in Examples 1, 2, and 3 of this invention. Figure 5 The elemental distribution of the transition metal-nitrogen-carbon catalyst Pb / Cu-CN prepared in Examples 1, 2, and 3 of this invention is shown. Figure 6 This is a comparison of the catalytic effects of the transition metal-nitrogen-carbon catalyst Pb / Cu-CN (10wt%) prepared in Examples 1, 2, and 3 of this invention on AP pyrolysis. Figure 7 The transition metal-nitrogen-carbon catalyst Pb / Cu-CN prepared in Example 2 of this invention 600(10wt%) Comparison of the catalytic effects of Catocene and Fe2O3, commonly used combustion catalysts for propellants, on AP pyrolysis; Figure 8 The transition metal-nitrogen-carbon catalyst Fe-CN prepared in Example 4 of this invention 800 DSC curve of (10wt%) blend with AP; Figure 9 The DSC curve of the transition metal-nitrogen-carbon catalyst Ni-CN (10wt%) and AP blend prepared in Example 5 of this invention is shown. Figure 10 The DSC curve of the transition metal-nitrogen carbon catalyst Co-CN (10wt%) and AP blend prepared in Example 6 of this invention is shown. Figure 11 The DSC curve of the transition metal-nitrogen-carbon catalyst Cr-CN (10wt%) and AP blend prepared in Example 7 of this invention is shown. Figure 12 The image shows the DSC curve of the transition metal-nitrogen-carbon catalyst Ni-CN (10wt%) and AP blend prepared in Example 8 of this invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] Example 1 A method for preparing a transition metal-nitrogen-carbon catalyst Pb / Cu-CN is illustrated in the following flowchart. Figure 2 As shown, it includes the following steps: Weigh 12.04 g of 1,10-phenanthroline, 3.27 g of C4H8O6Pb2, and 0.82 g of CuCl2·2H2O, and dissolve them in 250 mL of anhydrous ethanol. Maintain the solution in a constant temperature oil bath at 60 °C and mechanically stir at 300 r / min until uniformly dispersed. Weigh 0.84 g of activated carbon and transfer it to the solution, maintaining the temperature for 8 h. After washing with alternating centrifugation using water and ethanol as detergents, collect the product and dry it in a drying oven at 60 °C to obtain the catalyst precursor. Grind the precursor and place it in an alumina crucible, then transfer it to a tube furnace. Purge the furnace with N2 atmosphere for 30 min to purge air, then raise the temperature from room temperature to 400 °C at a rate of 5 °C / min and hold for 2 h. After naturally cooling to room temperature, collect the product to obtain the catalyst sample, named Pb / Cu-CN. 400 .

[0020] Pb / Cu-CN were imaged using a scanning electron microscope. 400 The micromorphology, such as Figure 3 As shown in (a), the particles exhibit an irregular, multi-folded cluster shape in terms of microscopic morphology, with a single particle size of approximately 3~5 μm.

[0021] X-ray diffraction was used to analyze Pb / Cu-CN 400 XRD analysis was performed, such as Figure 4 As shown, its characteristic peaks correspond well with the standard cards for Cu (PDF#01-1326) and Pb (PDF#04-0686), indicating that Cu and Pb elements do exist in the catalyst and are most likely distributed in the zero-valence state. The peaks appearing at around 25° and 28.5° correspond to amorphous carbon. XRD characterization further confirmed that the product obtained is a Pb-Cu co-supported carbon-based catalyst.

[0022] The Pb, Cu, C, and N elemental contents of the catalyst were analyzed and tested using ICP-OES combined with an automated elemental analyzer. The results are as follows: Figure 5 As shown, the test results show that the elemental distribution of the catalyst is as follows: C 79.04 wt%, N 8.04 wt%, Pb 4.35 wt%, Cu 2.42 wt%.

[0023] The prepared catalyst Pb / Cu-CN 400 The mixture was thoroughly mixed with AP at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 6 As shown, Pb / Cu-CN can be seen. 400 The introduction of Pb significantly alters the decomposition process of AP, as seen in the DSC curves of Pb / Cu-CN. 400The introduction of [agent] has little effect on the crystallization peak and low-temperature decomposition peak temperature of AP, but it can significantly advance the high-temperature decomposition peak temperature from the original 445.1℃ to 346.6℃, a shift of 98.5℃, demonstrating a significant catalytic effect.

[0024] Example 2 A method for preparing a transition metal-nitrogen-carbon catalyst Pb / Cu-CN includes the following steps: Weigh 12.04 g of 1,10-phenanthroline, 3.27 g of C4H8O6Pb2, and 0.82 g of CuCl2·2H2O, and dissolve them in 250 mL of anhydrous ethanol. Maintain the solution in a constant temperature oil bath at 60 °C and mechanically stir at 300 r / min until uniformly dispersed. Weigh 0.84 g of activated carbon and transfer it to the solution, maintaining the temperature for 8 h. After washing with alternating centrifugation using water and ethanol as detergents, collect the product and dry it in a drying oven at 60 °C to obtain the catalyst precursor. Grind the precursor and place it in an alumina crucible, then transfer it to a tube furnace. Purge the furnace with N2 atmosphere for 30 min to purge air, then raise the temperature from room temperature to 600 °C at a rate of 5 °C / min and maintain the temperature for 2 h. After naturally cooling to room temperature, collect the product to obtain the catalyst sample, named Pb / Cu-CN. 600 .

[0025] Pb / Cu-CN were imaged using a scanning electron microscope. 600 The micromorphology, such as Figure 3 As shown in (b), the particles exhibit an irregular, multi-folded cluster structure in terms of microstructure, with individual particles having a size of approximately 3–5 μm. Their microstructure is similar to that of Pb / Cu-CN. 400 No significant difference was found; meanwhile, element mapping was used to perform a local elemental scan, such as... Figure 3 As shown in (d), Pb, Cu and C can indeed be identified and their distribution is relatively uniform. However, due to the extremely high content of C, the image is covered by a large number of red dots representing C.

[0026] X-ray diffraction was used to analyze Pb / Cu-CN 600 XRD analysis was performed, such as Figure 4 As shown, it can be seen that its characteristic peaks, in terms of both position and intensity, are similar to those of Pb / Cu-CN. 400 No significant difference.

[0027] The Pb, Cu, C, and N elemental contents of the catalyst were analyzed and tested using ICP-OES combined with an automated elemental analyzer. The results are as follows: Figure 5 As shown, the test results show that the elemental distribution of the catalyst is as follows: C 77.69 wt%, N 9.26 wt%, Pb 5.21 wt%, Cu 2.77 wt%.

[0028] The prepared catalyst Pb / Cu-CN 400 The mixture was thoroughly mixed with AP at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 6 As shown, Pb / Cu-CN can be seen. 600 The introduction of Pb significantly alters the decomposition process of AP, as seen in the DSC curves of Pb / Cu-CN. 400 The introduction of this substance can merge the high and low temperature decomposition peaks of AP into one point at 336.3℃, transforming it from a two-stage dispersed exothermic process of a single component into a one-stage concentrated exothermic process. Compared to the original high temperature decomposition peak temperature of AP at 445.1℃, this is significantly advanced to 336.3℃, a substantial shift of 108.8℃, demonstrating a significant catalytic effect.

[0029] For a direct comparison of Pb / Cu-CN 600 Compared with the catalytic performance of commonly used propellant combustion catalysts Catocene and Fe2O3 on AP pyrolysis, commercially available Catocene and nano-Fe2O3 were blended with AP respectively in a mixing ratio of 1:9. The test conditions were N2 atmosphere with a heating rate of 10°C / min. The results are as follows. Figure 7 As shown, Pb / Cu-CN can be seen. 600 The catalytic performance of Pb / Cu-CN obtained in this embodiment is significantly better than that of nano-Fe2O3 and similar to that of Catocene for Pb pyrolysis. However, the absence of peak merging at high and low temperatures indicates that the introduction of Catocene failed to solve the problem of non-concentrated exothermic reaction of Pb. 600 The advantages of catalysts.

[0030] Pb / Cu-CN 600 It is mixed with AP at a mass ratio of 1:9, i.e., Pb / Cu-CN. 600 A component comprising 10 wt% of the total mass of the blend was subjected to laser ignition experiments together with AP powder under the same excitation conditions. The results are as follows: Figure 1 As shown, under the same ignition conditions, the AP powder was hardly activated, while the powder mixed with the catalyst burned vigorously, emitting a bright yellow light. This largely indicates that the catalyst Pb / Cu-CN... 600 It can lower the ignition threshold of AP, promote its combustion process, and significantly improve its ignition performance.

[0031] Example 3 A method for preparing a transition metal-nitrogen-carbon catalyst Pb / Cu-CN includes the following steps: Weigh 12.04 g of 1,10-phenanthroline, 3.27 g of C4H8O6Pb2, and 0.82 g of CuCl2·2H2O, and dissolve them in 250 mL of anhydrous ethanol. Maintain the solution in a constant temperature oil bath at 60 °C and mechanically stir at 300 r / min until uniformly dispersed. Weigh 0.84 g of activated carbon and transfer it to the solution, maintaining the temperature for 8 h. After washing with alternating centrifugation using water and ethanol as detergents, collect the product and dry it in a drying oven at 60 °C to obtain the catalyst precursor. Grind the precursor and place it in an alumina crucible, then transfer it to a tube furnace. Purge the furnace with N2 atmosphere for 30 min to purge air, then raise the temperature from room temperature to 800 °C at a rate of 5 °C / min and hold for 2 h. After naturally cooling to room temperature, collect the product to obtain the catalyst sample, named Pb / Cu-CN. 800 .

[0032] Pb / Cu-CN were imaged using a scanning electron microscope. 800 The micromorphology, such as Figure 3 As shown in (c), the particles exhibit an irregular, multi-folded cluster structure in terms of microstructure, with individual particles having a size of approximately 3–5 μm. Their microstructure is similar to that of Pb / Cu-CN. 400 and Pb / Cu-CN 600 There was no significant difference, but the degree of clustering was somewhat intensified.

[0033] X-ray diffraction was used to analyze Pb / Cu-CN 800 XRD analysis was performed, such as Figure 4 As shown, it can be seen that its characteristic peaks, in terms of both position and intensity, are similar to those of Pb / Cu-CN. 400 Pb / Cu-CN 600 No significant difference.

[0034] The Pb, Cu, C, and N elemental contents of the catalyst were analyzed and tested using ICP-OES combined with an automated elemental analyzer. The results are as follows: Figure 5 As shown, the test results show that the elemental distribution of the catalyst is as follows: C 81.37wt%, N 8.59wt%, Pb 4.76wt%, Cu 2.93wt%.

[0035] The prepared catalyst Pb / Cu-CN 800 The mixture was thoroughly mixed with AP at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 6 As shown, Pb / Cu-CN can be seen. 800 The introduction of Pb significantly alters the decomposition process of AP, as seen in the DSC curves of Pb / Cu-CN. 800The introduction of this substance can cause the low-temperature decomposition peak temperature of AP to be delayed and the high-temperature decomposition peak temperature to be advanced. The low-temperature decomposition peak temperature is delayed from the original 299.0°C to 315.8°C, while the high-temperature decomposition peak temperature is significantly advanced from the original 445.1°C to 354.0°C, a significant advance of 91.1°C, which has excellent catalytic effect.

[0036] Example 4 A method for preparing a transition metal-nitrogen-carbon catalyst Fe-CN includes the following steps: 12.04 g of 1,10-phenanthroline and 2.61 g of ferrocene were weighed and dissolved in 250 mL of a mixture of anhydrous ethanol and N,N-dimethylformamide (volume ratio 1:1). The mixture was kept at a constant temperature of 50 °C in an oil bath and mechanically stirred at a stirring rate of 200 r / min until it was evenly dispersed. 0.84 g of activated carbon was weighed and transferred to the solution, and the mixture was stirred for 10 h. The product was collected after alternating centrifugation with water and ethanol as detergents and dried in a drying oven at 60 °C to obtain the catalyst precursor. The precursor was ground and placed in an alumina crucible and transferred to a tube furnace. An Ar atmosphere was introduced for 30 min to purge the air, and then the temperature was increased from room temperature to 400 °C at a rate of 5 °C / min and held for 2 h. After natural cooling to room temperature, the product was collected to obtain the catalyst sample, named Fe-CN.

[0037] The prepared catalyst Fe-CN and AP were thoroughly mixed at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 8 As shown, the introduction of Fe-CN alters the decomposition process of AP. The low-temperature decomposition peak is slightly delayed from AP's own 299.0℃ to 312.3℃, a delay of 13.3℃, ​​while the high-temperature decomposition peak is advanced from 445.1℃ to 356.1℃, a shift of 89.0℃.

[0038] Example 5 A method for preparing a transition metal-nitrogen-carbon catalyst Ni-CN includes the following steps: 12.04 g of 1,10-phenanthroline and 4.35 g of Ni(CH3COO)2·4H2O were weighed and dissolved in 250 mL of anhydrous ethanol. The solution was kept at a constant temperature of 70 °C in an oil bath and mechanically stirred at a stirring rate of 250 r / min until it was uniformly dispersed. 0.86 g of activated carbon was weighed and transferred to the solution, and stirred for 12 h. The product was collected after alternating centrifugation with water and ethanol as detergents, and then transferred to a drying oven to dry, obtaining the catalyst precursor. The precursor was ground and placed in an alumina crucible and transferred to a tube furnace. N2 atmosphere was introduced for 30 min to purge the air, and then the temperature was increased from room temperature to 600 °C at a rate of 10 °C / min and held for 3 h. After natural cooling to room temperature, the product was collected to obtain the catalyst sample, named Ni-CN.

[0039] The prepared catalyst Ni-CN and AP were thoroughly mixed at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 9 As shown, the introduction of Ni-CN alters the decomposition process of AP. The low-temperature decomposition peak is slightly advanced from AP's own 299.0℃ to 294.8℃, an advance of 4.2℃, but the peak shape changes from a sharp narrow peak to a wider shoulder peak; the high-temperature decomposition peak is advanced from 445.1℃ to 372.1℃, an advance of 73.0℃.

[0040] Example 6 A method for preparing a transition metal-nitrogen-carbon catalyst Co-CN includes the following steps: 12.04 g of 1,10-phenanthroline and 5.30 g of Co(NO3)2·4H2O were weighed and dissolved in 250 mL of N,N-dimethylformamide. The solution was kept at a constant temperature of 60 °C in an oil bath and mechanically stirred at a stirring rate of 250 r / min until it was evenly dispersed. 0.83 g of activated carbon was weighed and transferred to the solution, and stirred for 10 h. The product was collected after alternating centrifugation with water and ethanol as detergents, and then transferred to a drying oven to dry, obtaining the catalyst precursor. The precursor was ground and placed in an alumina crucible and transferred to a tube furnace. An Ar atmosphere was introduced for 30 min to purge the air, and then the temperature was increased from room temperature to 600 °C at a rate of 10 °C / min and held for 4 h. After naturally cooling to room temperature, the product was collected to obtain the catalyst sample, named Co-CN.

[0041] The prepared catalyst Co-CN and AP were thoroughly mixed at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 10 As shown, the introduction of Co-CN alters the decomposition process of AP. The low-temperature decomposition peak is slightly delayed from AP's own 299.0℃ to 302.8℃, a delay of 3.8℃; the high-temperature decomposition peak is advanced from 445.1℃ to 339.1℃, a shift of 106.0℃.

[0042] Example 7 A method for preparing a transition metal-nitrogen-carbon catalyst Cr-CN includes the following steps: 12.04 g of 1,10-phenanthroline and 2.78 g of Cr(CH3COO)3 were weighed and dissolved in 250 mL of anhydrous ethanol. The solution was kept at a constant temperature of 60 °C in an oil bath and mechanically stirred at a stirring rate of 200 r / min until it was evenly dispersed. 0.83 g of activated carbon was weighed and transferred to the solution, and the mixture was stirred for 8 h. The product was collected after alternating centrifugation with water and ethanol as detergents, and then transferred to a drying oven to dry, thus obtaining the catalyst precursor. The precursor was ground and placed in an alumina crucible and transferred to a tube furnace. An Ar atmosphere was introduced for 30 min to purge the air, and then the temperature was increased from room temperature to 600 °C at a rate of 2 °C / min and held for 2 h. After naturally cooling to room temperature, the product was collected to obtain the catalyst sample, named Cr-CN.

[0043] The prepared catalyst Cr-CN and AP were thoroughly mixed at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 11 As shown, the introduction of Cr-CN causes the high and low temperature decomposition peak temperatures of AP to advance to varying degrees. The low temperature decomposition peak is advanced slightly by 1.1℃ to 297.9℃, and the high temperature decomposition peak temperature is advanced by 63.0℃ from 445.1℃ to 382.1℃.

[0044] Example 8 A method for preparing a transition metal-nitrogen-carbon catalyst Mn-CN includes the following steps: 12.04 g of 1,10-phenanthroline and 3.73 g of Mn(CH3COO)2·4H2O were weighed and dissolved in 250 mL of anhydrous ethanol. The solution was kept at a constant temperature of 60 °C in an oil bath and mechanically stirred at a stirring rate of 300 r / min until it was uniformly dispersed. 0.85 g of activated carbon was weighed and transferred to the solution, and stirred for 10 h. The product was collected after alternating centrifugation with water and ethanol as detergents, and then transferred to a drying oven to dry, obtaining the catalyst precursor. The precursor was ground and placed in an alumina crucible and transferred to a tube furnace. N2 atmosphere was introduced for 30 min to purge the air, and then the temperature was increased from room temperature to 600 °C at a rate of 5 °C / min and held for 2 h. After natural cooling to room temperature, the product was collected to obtain the catalyst sample, named Mn-CN.

[0045] The prepared catalyst Mn-CN and AP were thoroughly mixed at a mass ratio of 1:9, and simultaneous thermal analysis (TG-DSC) was performed. The results are as follows: Figure 12 As shown, the introduction of Mn-CN causes the low-temperature decomposition peak of AP to change from a narrow and sharp peak shape to a broad and flat shoulder peak, with the peak temperature slightly delayed by 0.7℃ to 299.7℃, and the high-temperature decomposition peak temperature advanced from 445.1℃ to 397.9℃, an advance of 47.2℃.

[0046] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A transition metal-nitrogen-carbon catalyst, characterized in that, The transition metal-nitrogen-carbon catalyst has an elemental composition of M-CN, where M is a transition metal and CN is a nitrogen-doped carbon support; the transition metal is dispersed and supported on the nitrogen-doped carbon support; and the particle size of the transition metal-nitrogen-carbon catalyst is 3~5μm.

2. The transition metal-nitrogen-carbon catalyst according to claim 1, characterized in that, The transition metal is selected from one or more of iron, cobalt, nickel, copper, lead, chromium, and manganese.

3. A method for preparing a transition metal-nitrogen-carbon catalyst according to claim 1, characterized in that, Using transition metal salts, 1,10-phenanthroline, and activated carbon as raw materials, a catalyst precursor is first obtained by an oil bath reaction in an organic solvent system; the catalyst precursor is then subjected to a high-temperature carbonization reaction under an inert atmosphere to finally obtain a transition metal-nitrogen-carbon catalyst.

4. The method for preparing the transition metal-nitrogen-carbon catalyst according to claim 3, characterized in that, Includes the following steps: S1. A certain amount of transition metal salt and 1,10-phenanthroline are dispersed in an organic solvent, ultrasonicated to make them evenly dispersed, transferred to a constant temperature oil bath, and stirred at the same time during the heat preservation process to obtain the first mixture. S2. Add a certain amount of activated carbon to the first mixture, continue stirring and keep warm for a specified time, then turn off the heating and allow it to cool naturally to obtain the product; S3. The product obtained by alternating filtration and washing with water and alcohol was dried and ground to obtain the catalyst precursor; S4. The catalyst precursor is subjected to a high-temperature carbonization reaction under N2 or Ar to obtain the transition metal-nitrogen-carbon catalyst.

5. The method for preparing the transition metal-nitrogen-carbon catalyst according to claim 4, characterized in that, In step S1: The transition metal salts include one or more of hydrochloride, nitrate, acetate, sulfate, and ferrocene; The organic solvent is anhydrous ethanol and / or N,N-dimethylformamide; The molar ratio of transition metal salt to 1,10-phenanthroline is 1:3 to 1:

5.

6. The method for preparing the transition metal-nitrogen-carbon catalyst according to claim 4, characterized in that, The stirring time in step S1 is 20~30 min; the heat preservation temperature range in steps S1 and S2 is 50℃~70℃; the stirring rate is 200~300 r / min; the stirring and heat preservation time in step S2 is 8~12 h.

7. The method for preparing the transition metal-nitrogen-carbon catalyst according to claim 4, characterized in that, In step S4, N2 or Ar is introduced before the high-temperature carbonization reaction to purge the air; the programmed heating rate of the high-temperature carbonization reaction is 2℃ / min~10℃ / min, the holding temperature is controlled at 400℃~800℃, and the holding time is controlled at 2h~4h.

8. The application of a transition metal-nitrogen-carbon catalyst as described in claim 1 or 2 in a propellant.

9. The application according to claim 8, characterized in that, The transition metal-nitrogen-carbon catalyst is used as a catalyst in the thermal decomposition of AP, AP-based solid propellants, and the combustion catalysis of explosives.

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