A carbon dot / copper nanocomposite for solid propellant combustion catalyst

Abstract

The application discloses a carbon dot / copper nanocomposite for a solid propellant combustion catalyst, uses carbon dots and copper acetylacetonate as reaction precursors, uses water and N,N'-dimethylformamide as mixed reaction solvents, reduces divalent copper ions into nanometer copper elements in a hydrothermal process by using the reducing property of the carbon dots, and performs in-situ growth, and finally obtains the carbon dot / copper nanocomposite. The application can effectively exert the synergistic effect of the carbon dots and nanometer metal copper, has high combustion catalytic performance on energetic materials, and can be used for combustion catalysis of the solid propellant.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of energetic materials, and relates to a carbon dot / copper nanocomposite for a solid propellant combustion catalyst. BACKGROUND

[0002] Solid propellant is an important component of energetic materials, and is the main power source of strategic missiles, space vehicles, various solid engine and kinetic energy interception weapons. Combustion catalysis is the core of solid propellant technology, which not only affects the energy release law of the propellant, but also plays a decisive role in the reliability of the engine, the precision of the rocket weapon and the range. Combustion performance adjustment is one of the key technologies in the research of modern solid propellant, and using a combustion catalyst is the best way to adjust the combustion performance of the solid propellant.

[0003] In recent years, carbon-based nanomaterials including carbon nanotubes (CNTs), graphene (GO), nano carbon black and nano activated carbon have been widely studied by domestic and foreign researchers for application in propellants. As a lightweight carbon material, carbon-based nanocomposites have unique advantages in structure, physical and chemical properties and thermodynamics, such as volume effect, surface effect and quantum size effect, which can effectively improve the burning rate of energetic materials, reduce mechanical sensitivity and improve energy release rate. However, at present, the application of carbon-based nanocomposites in solid propellants generally has problems of active sites and dispersion degree to be improved, and how to effectively further improve the burning rate of propellants, reduce the pressure index, promote the establishment of a wider combustion platform and more widely applicable propellant combustion work has become a problem to be solved for current nanocomposites.

[0004] Carbon dots are a new type of environmentally friendly nanomaterial, and few people have studied them in the field of solid propellant combustion catalysts. At present, there is a lack of preparation method of carbon dot-copper dual composite combustion catalyst. The introduction of carbon dots and their composites into the field of application research of solid propellant combustion catalysts is expected to reveal the catalytic mechanism of carbon materials in solid propellants, change the problems of low yield, difficult process production and high cost of traditional carbon nanomaterials, and provide a new feasible research direction for further improvement of the performance adjustment of propellant combustion catalysts. SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a carbon dot / copper nanocomposite for a solid propellant combustion catalyst, which solves the technical problem that the combustion catalytic performance of the existing solid propellant combustion catalyst needs to be further improved. The method can effectively exert the synergistic effect between the components of the composite material, so that the thermal decomposition catalytic effect on energetic materials is further improved.

[0006] To solve the above technical problems, the application adopts the following technical solutions to achieve the purpose:

[0007] A carbon dot / copper nanocomposite for solid propellant combustion catalyst, which is a binary composite of carbon dots and nanometer copper elements, and raw materials thereof include carbon dots, copper acetylacetone, and a mixed reaction solvent of water and N,N'-dimethylformamide.

[0008] The preparation method of the carbon dot / copper nanocomposite for solid propellant combustion catalyst comprises the following steps:

[0009] The carbon dots are dispersed in pure water to prepare a suspension, the suspension is ultrasonically treated, and rotary evaporation is performed, and the step is repeated until the solution is neutral, and then the treated carbon dot powder is dried in a 70 DEG C oven.

[0010] The treated carbon dot powder and copper acetylacetone are used as reaction precursors, water and N,N'-dimethylformamide are used as a mixed reaction solvent, and constant temperature stirring is performed at room temperature for 0.5-1 h, and then in-situ growth is performed in a hydrothermal reaction kettle.

[0011] The mixed suspension after reaction is centrifuged, and the precipitate is washed with water and ethanol until the centrifugal supernatant is colorless, and then the mixture is dried at 60 DEG C, and finally the carbon dot / copper nanocomposite for solid propellant combustion catalyst is obtained.

[0012] The application also comprises the following technical features:

[0013] Specifically, the concentration of the suspension is (2-2.5) g / L.

[0014] Specifically, the suspension is ultrasonically treated for 1-2 h, and the rotary evaporation condition of the suspension is rotary evaporation at 80 DEG C for 0.5-1 h.

[0015] Specifically, the mass ratio of the carbon dot powder to copper acetylacetone in the reaction precursor is (2-2.5):1.

[0016] Specifically, the volume ratio of N,N-dimethylformamide to water in the mixed reaction solvent is (3-4):1.

[0017] Specifically, the concentration of the reaction precursor in the mixed reaction solvent is 8 g / L.

[0018] Specifically, the reaction condition in the hydrothermal reaction kettle is that the reaction system is raised from room temperature to 160 DEG C in 1 h, and then kept at 160 DEG C for 2 h, and then cooled to 30 DEG C at a cooling rate of 2.2 DEG C / h.

[0019] Specifically, the centrifugal treatment condition of the mixed suspension after reaction is centrifugation at 8000 r / min for 15 min.

[0020] The carbon dot / copper nanocomposite for solid propellant combustion catalyst is applied as an energetic material combustion catalyst.

[0021] Compared with the prior art, the present application has the following technical effects:

[0022] (1) The present application introduces carbon dots as a new type of lightweight carbon material into the field of energetic material combustion catalysts by pretreating the carbon dots, obtains carbon dot powder that can be applied to solid propellant combustion catalysts, has an overall size of about 3 nm, and can effectively promote the thermal decomposition of energetic components in insensitive propellants and improve the energy of the propellant.

[0023] (2) The present application effectively prevents the agglomeration of nano-copper particles, provides more active sites for the thermal decomposition of energetic materials, and plays a synergistic catalytic effect between carbon materials and metals. By using the reducing property of carbon dots and adjusting the proportion of the precursor, a two-component composite is obtained. Compared with three components, two components are more conducive to analyzing the effect of each component on catalytic thermal decomposition and more conducive to revealing the catalytic effect of carbon materials in energetic materials. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 TEM images of the carbon dot / copper nanocomposite at different magnifications.

[0025] Figure 2 XRD results of the carbon dot / copper nanocomposite.

[0026] Figure 3 EDS and Mapping results of the carbon dot / copper nanocomposite.

[0027] Figure 4 XPS results of the carbon dot / copper nanocomposite.

[0028] Figure 5 DSC curve of the carbon dot / copper nanocomposite.

[0029] Figure 6 DSC-MS curve of the carbon dot / copper nanocomposite at 10℃ / min.

[0030] Figure 7 DSC-FTIR curve of the carbon dot / copper nanocomposite at 10℃ / min.

[0031] Figure 8 Ignition delay time curve of the carbon dot / copper nanocomposite.

[0032] Figure 9 Flame development process of the carbon dot / copper nanocomposite at a laser power of 46W / cm 2 . DETAILED DESCRIPTION

[0033] The application provides a carbon dot / copper nanocomposite for a solid propellant combustion catalyst, adopts synthesized oxidized etching carbon dots and acetylacetone copper salt, utilizes the reducing property of the carbon dots to reduce the divalent copper ions into nanometer copper elements in a hydrothermal process, and performs in-situ growth, and finally obtains the carbon dot / copper nanocomposite. The material can effectively exert the synergistic effect of the carbon dots and the nanometer metal copper, promotes the combustion catalysis of the solid propellant, and shows excellent catalysis.

[0034] It should be noted that in the application, CDs is a short name of carbon dots (English name Carbon Dots), CDs / Cu is a short name of a composite formed by carbon dots and copper, DMF is a short name of N,N'-dimethylformamide, and TKX-50 is a short name of 1,1'-dihydroxy-5,5'-tetrazolium blue.

[0035] The application is implemented in the following manner: carbon dots (CDs) and acetylacetone copper are prepared in a mixed solution of DMF and water as a solvent phase, and a hydrothermal reaction is performed under high temperature and high pressure conditions in a hydrothermal reaction kettle.

[0036] In a thermal analysis test, the mass ratio of TKX-50 to CDs / Cu in a mixed sample of 1,1'-dihydroxy-5,5'-tetrazolium blue (TKX-50) and carbon dot / copper nanocomposite (CDs / Cu) is 10:1.

[0037] The following gives specific embodiments of the application, and it should be noted that the application is not limited to the following specific embodiments, and any equivalent transformation made on the basis of the technical solutions of the application falls within the protection scope of the application.

[0038] Embodiment 1:

[0039] The embodiment provides a carbon dot / copper nanocomposite for a solid propellant combustion catalyst and a preparation method thereof, and specifically includes the following steps:

[0040] The carbon dots (CDs) are dispersed in pure water to prepare a suspension with a concentration of 2 g / L, the suspension is ultrasonically treated for 1-2 hours, rotary evaporation is performed at 80℃ for 0.5-1 hour, the above steps are repeated until the solution is neutral, and then drying is performed in a 70℃ oven to obtain treated CDs that can be used for solid propellant. Specifically, the CDs in the embodiment are prepared by using coal tar pitch to prepare multicolor luminescent adjustable carbon dots according to the patent ZL201610534465.4, and the carbon dots (CDs) are obtained by selectively etching medium-temperature coal tar pitch with formic acid and hydrogen peroxide.

[0041] The 800-1000 mg (800 mg is preferred in this example) of the above treated CDs, 400 mg of copper acetylacetonate were dissolved in DMF / H2O (volume ratio (3-4):1, and the preferred volume ratio v:v=4:1 in this example). After stirring for 1 h until complete dissolution, the reaction kettle was filled with 100 ml. The reaction kettle was raised from room temperature to 160°C in the oven for 1 h, and kept at 160°C for 2 h, and then cooled to 30°C at a rate of 2.2°C / min, and then the reaction kettle was taken out.

[0042] The brownish solution was observed to have a dark brown precipitate at the bottom of the reaction kettle, which was centrifuged at 8000 r / min for 15 min, washed with ethanol and water, and dried to obtain a dark brown powder of CDs / Cu.

[0043] The components and morphological structure characterization are shown in Figures 1-4 .

[0044] The morphological characteristics of CDs / Cu were analyzed by using transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The morphological characteristics of CDs and CDs / Cu nanocomposites were analyzed by TEM and HRTEM, as shown in Figure 1 . The results clearly show that the overall CDs / Cu nanocomposites exhibit spherical morphology, and the composite material has two different orientation lattice fringes, in which 0.241 nm corresponds to CDs, and the 0.208 nm lattice spacing corresponds to the (111) crystal plane of Cu. This means that the small particles of CDs are combined with Cu particles.

[0045] The structure and composition of CDs / Cu were characterized by using X-ray diffraction (XRD). The Cu Kα source was used, the measurement angle range (2θ) was 5-90°, and the scanning rate was 5° / min. The XRD results of CDs / Cu are shown in Figure 2 . The experimental diffraction pattern of CDs / Cu does not have obvious diffraction peaks, and the diffraction intensity of Cu is consistent with the standard PDF card (JCPDS NO. 85-1236), which confirms that Cu 2+ is reduced to Cu element.

[0046] The EDS Mapping results of CDs / Cu are shown in Figure 3 . The results show that the CDs / Cu sample contains four elements of C, O, H, and Cu, in which O comes from the surface carboxyl functional group of CDs.

[0047] The valence state of Cu element in CDs / Cu was further characterized by X-ray photoelectron spectroscopy (XPS), as shown in Figure 4 . The binding energy displacement difference was observed from the two samples: the Cu 2+In the high-resolution XPS, two strong peaks are located at 933.8 and 953.7 eV, respectively, corresponding to Cu. 2+ 2p 3 / 2 and 2p 1 / 2 When carbon dots are added to form a CDs / Cu complex, a shift in the binding energy occurs, with strong peaks at 952.45 and 932.2 eV, corresponding to Cu. 0 2p 3 / 2 and 2p 1 / 2 This confirms the presence of Cu in CDs / Cu. 0 In the hydrothermal reaction, Cu 2+ It is reduced to elemental Cu, eventually forming CDs / Cu.

[0048] from Figures 1 to 4 As can be clearly seen, the dark brown powder obtained in this embodiment is the target product CDs / Cu.

[0049] Example 2:

[0050] This embodiment illustrates the application of CDs / Cu from Example 1 as a combustion catalyst for energetic materials. Specifically, as follows... Figures 5 to 8 As shown; Figure 5 As shown, TKX-50 exhibits two peaks during pyrolysis. At a heating rate of 10℃ / min, the decomposition of TKX-50 before and after the addition of CDs / Cu results in different DSC curves. The addition of CDs / Cu reduces the low-temperature decomposition peak temperature of TKX-50 by 16.1℃, and the high-temperature decomposition peak becomes less pronounced. Compared to CDs and Cu alone, and their mechanical mixture, CDs / Cu demonstrates better catalytic performance.

[0051] The effects of CDs and CDs / Cu addition on the pyrolysis products of TKX-540 were investigated using DSC-MS-FTIR technology in the temperature range of 40-800℃ under an inert atmosphere and a heating rate of 10℃ / min. The results are as follows: Figure 6 and Figure 7 As shown in the figure, NH3 (m / z = 17), H2O (m / z = 18), HCN (m / z = 27), NH2 (m / z = 16), NO (m / z = 30), CO2 / N2O (m / z = 44), and N2 / CO (m / z = 28) were detected. The addition of CDs and CDs / Cu did not significantly alter the pyrolysis gaseous products of TKX-50, but the percentage of gaseous products changed significantly. Based on this, the molar percentage of the main gaseous products for each sample was calculated. The addition of CDs increased the N2 / CO content, while decreasing the CO2 / N2O content. Furthermore, the addition of CDs / Cu promoted the conversion of decomposition products from HCN to H2O.

[0052] The ignition and combustion processes of TKX-50 with and without CDs and CDs / Cu were studied using a laser ignition device. The exposure time of the high-speed camera was 0.2 ms, and the shooting frequency was 0.5 ms. The ignition delay time varied with the laser power density as shown in Figure 8 The flame development process is shown in Figure 9 The minimum ignition power density of TKX-50 is effectively reduced after adding CDs, and the minimum ignition of TKX-50 is further reduced after adding CDs / Cu. Overall, the mixed sample of CDs / Cu and TKX-50 has a smaller ignition delay time than that of CDs and TKX-50 and pure TKX-50 at each power density. In Figure 9 The flame propagation image shows that the flame growth rate of CDs / Cu is significantly accelerated at a laser power density of 46 W / cm 2 The flame shows a bright color, and the complete combustion time is significantly shortened compared with pure TKX-50, and the flame propagation speed is doubled. From the flame propagation speed and the flame area, it can be inferred that CDs / Cu has more significant advantages in the ignition and combustion of TKX-50.

[0053] The carbon dot / copper nanocomposite prepared by the application has high combustion catalytic performance for energetic materials and can be used for combustion catalysis of solid propellants.

Claims

1. A carbon dot / copper nanocomposite for a solid propellant combustion catalyst, characterized by, The composite is a binary composite of carbon dots and copper nanoparticles, and raw materials thereof include carbon dots, copper acetylacetate, and a mixed reaction solvent of water and N,N'-dimethylformamide. The preparation method of the carbon dot / copper nanoparticle composite for the solid propellant combustion catalyst comprises the following steps: The carbon dots are dispersed in pure water to prepare a suspension, the suspension is ultrasonically treated, and rotary evaporation is performed, and the step is repeated until the solution is neutral, and then the treated carbon dot powder is dried in a 70 DEG C oven to obtain the treated carbon dot powder; The treated carbon dot powder and copper acetylacetate are used as reaction precursors, water and N,N'-dimethylformamide are used as a mixed reaction solvent, and constant temperature stirring is performed at room temperature for 0.5-1 h, and then in-situ growth is performed in a hydrothermal reaction kettle; The mixed suspension after the reaction is centrifuged, and the precipitate is washed with water and ethanol until the centrifugal supernatant is colorless, and then the precipitate is dried at 60 DEG C to obtain the carbon dot / copper nanoparticle composite for the solid propellant combustion catalyst. The mass ratio of the carbon dot powder to copper acetylacetate in the reaction precursors is (2-2.5):

1.

2. The carbon dot / copper nanocomposite for a solid propellant combustion catalyst according to claim 1, wherein The concentration of the suspension is 2-2.5 g / L.

3. The carbon dot / copper nanocomposite for a solid propellant combustion catalyst according to claim 1, wherein the carbon dot / copper nanocomposite is prepared by mixing the carbon dot and the copper in a weight ratio of 1:1 to 1:

10. The suspension is ultrasonically treated for 1-2 h, and the rotary evaporation of the suspension is performed at 80 DEG C for 0.5-1 h.

4. The carbon dot / copper nanocomposite for a solid propellant combustion catalyst according to claim 1, wherein The volume ratio of N,N-dimethylformamide to water in the mixed reaction solvent is (3-4):

1.

5. The carbon dot / copper nanocomposite for a solid propellant combustion catalyst according to claim 1, wherein The concentration of the reaction precursors in the mixed reaction solvent is 8 g / L.

6. The carbon dot / copper nanocomposite for solid propellant combustion catalyst according to claim 1, wherein The reaction conditions in the hydrothermal reaction kettle are as follows: the reaction system is raised from room temperature to 160 DEG C in 1 h, and then kept at 160 DEG C for 2 h, and then cooled to 30 DEG C at a cooling rate of 2.2 DEG C / h.

7. The carbon dot / copper nanocomposite for solid propellant combustion catalyst according to claim 1, wherein The centrifugal treatment conditions of the mixed suspension after the reaction are as follows: centrifugation at 8000 r / min for 15 min.

8. The carbon dot / copper nanoparticle composite for the solid propellant combustion catalyst according to claim 1 is used as a combustion catalyst for energetic material TKX-50.

Images