CN115849996A - Potassium-doped maghemite-coupled graphene composite combustion catalyst, and preparation method and application thereof - Google Patents

Abstract

The invention discloses a potassium-doped maghemite-coupled graphene composite combustion catalyst and its preparation method and application. The graphene oxide, metal salt precursor and potassium-containing precipitant are dissolved in a mixed solvent of ethylene glycol and water , for hydrothermal reaction to obtain potassium-doped maghemite-coupled graphene composite combustion catalyst. On the one hand, K-doped γ-Fe ₂ O ₃ has excellent catalytic activity for the exothermic decomposition of octogold; on the other hand, K-Fe ₂ O ₃ is uniformly and stably attached to the graphene surface through the in-situ growth process. The invention adopts conventional reagents, does not need to add any surfactant, and has simple process, readily available raw materials, and can be prepared in batches. The catalyst can reduce the sensitivity of the propellant components and significantly improve the decomposition efficiency of the main components of the propellant.

Description

A kind of potassium-doped maghemite coupled graphene composite combustion catalyst and preparation method and application

technical field

The invention is applied to the field of combustion catalysts for solid propellants, and in particular relates to a potassium-doped maghemite-coupled graphene composite combustion catalyst, a preparation method and application.

Background technique

As an important part of the national defense technology system, weapons and equipment are required to have the characteristics of high specific impulse, high density and high combustion rate, and the combustion catalyst is one of the indispensable key components. Therefore, the development of new high-efficiency combustion catalysts is of great significance to improve the ignition and combustion performance of propellants. Graphene carbon materials can be used as co-catalysts in solid propellants, and can be used in combination with nano-metal oxide catalysts. Its large specific surface area and excellent thermal conductivity provide a good material basis for improving the dispersion and catalytic activity of nano-catalysts. And with its super mechanical strength, when the energetic material is combined with graphene, graphene can act as a desensitizing agent and a toughening agent. In addition, a small amount of potassium is also doped in the complex, and reports indicate that potassium salts can inhibit the secondary combustion of solid propellants, which can be applied to low characteristic signal propellants. However, the current traditional combustion catalysts have the disadvantages of low activity, single function, and excessive addition of energy-free additives will inevitably reduce the overall energy density of the propellant.

Contents of the invention

In order to overcome the problems in the prior art, the object of the present invention is to provide a potassium-doped maghemite coupled graphene composite combustion catalyst and its preparation method and application. The composite catalyst uses "γ-Fe ₂ O ₃ , graphene and Potassium" three components complement each other and synergize, so that the composite catalyst has the triple effect of "catalysis-sensitivity reduction-flame suppression".

The present invention is achieved through the following technical solutions:

A potassium-doped maghemite-coupled graphene composite combustion catalyst, dissolving graphene oxide, metal salt precursor and potassium-containing precipitant in a mixed solvent of ethylene glycol and water, and performing hydrothermal reaction to obtain potassium-doped Heteromaghemite-coupled graphene composite combustion catalysts.

Further, the metal salt precursor is Fe(NO) ₃ ·9H ₂ O.

Further, the precipitation agent is potassium hydroxide.

Further, the solvent is a mixed solvent with a volume ratio of water and ethylene glycol of 1:2.

Further, the mass ratio of graphene oxide to metal salt precursor is 0.04˜0.1:1.

Further, the mass ratio of graphene oxide to potassium-containing precipitant is 0.01˜0.025:1.

Further, the ratio of graphene oxide to solvent is 10-25mg:15mL.

Further, the temperature of the hydrothermal reaction is 150-160° C., and the time is 10-12 hours.

A potassium-doped maghemite-coupled graphene composite combustion catalyst prepared according to the above-mentioned method, in which the crystal form of iron oxide in the catalyst is gamma-type, the microscopic appearance of the catalyst is flower-clustered, and potassium is doped.

A potassium-doped maghemite-coupled graphene composite combustion catalyst prepared according to the method described above is used as a combustion catalyst for a propellant, and its application in catalyzing the combustion of a solid propellant.

Compared with the prior art, the present invention has the following beneficial technical effects:

The invention adopts graphene oxide, metal salt precursor and potassium-containing precipitant as raw materials, and prepares a potassium-doped maghemite-coupled graphene composite combustion catalyst through hydrothermal reaction; the catalyst is K-Fe ₂ O ₃ / G complex. On the one hand, K-Fe ₂ O ₃ has excellent catalytic activity for the exothermic decomposition of octogold; on the other hand, K-Fe ₂ O ₃ can be uniformly and stably attached to the graphene surface through the in-situ growth process. The invention adopts conventional reagents, does not need to add any surfactant, and has simple process, readily available raw materials, and can be prepared in batches.

The potassium-doped maghemite-coupled graphene composite combustion catalyst of the invention can be used as a combustion catalyst for solid propellants. Potassium in the compound can inhibit the secondary combustion of CO, _H2 and oxygen in the gas discharged from the nozzle of the rocket engine when the propellant is burned, and reduce the harm. The catalyst can significantly increase the exothermic decomposition rate of octogold, the main component of energetic materials, and has application prospects in the field of combustion catalysts for solid propellants.

Description of drawings

Fig. 1 is the XRD figure of comparative example 1, comparative example 2, embodiment 1, embodiment 2 products.

FIG. 2 is a TEM image of K-Fe ₂ O ₃ prepared in Comparative Example 1.

Fig. 3 is a TEM image of K-Fe ₂ O ₃ /G-1 prepared in Example 1.

FIG. 4 is the XPS full spectrum of K-Fe ₂ O ₃ prepared in Comparative Example 1.

Fig. 5 is the heat flow curve of HMX under the action of K-Fe ₂ O ₃ and K-Fe ₂ O ₃ /G.

Detailed ways

The present invention is illustrated by specific examples, but the present invention is not limited thereto. The graphene oxide is prepared by the hummer method. All other reagents and materials can be obtained from commercial sources.

The present invention adopts a one-step hydrothermal method, uses graphene oxide and metal salt precursors as raw materials, uses a mixed solution of deionized water and ethylene glycol (volume ratio 1:2) as a solvent, and uses potassium hydroxide as a precipitating agent. The K-Fe ₂ O ₃ /G composite, which is potassium-doped maghemite-coupled graphene composite combustion catalyst, can be prepared by keeping the temperature at 150-160° C. for 10-12 hours.

Specifically, the metal salt precursor is added to the graphene oxide solution, and then an aqueous inorganic alkali solution is added, stirred and mixed uniformly, and then subjected to a hydrothermal reaction to obtain a potassium-doped maghemite-coupled graphene composite combustion catalyst.

Wherein, the hydrothermal reaction temperature is 150-160° C., and the reaction time is 12 hours.

The metal salt precursor is Fe(NO) ₃ ·9H ₂ O.

Neither the flower cluster structure in the present invention nor the gamma crystal hematite material can be obtained by using ferric sulfate or potassium ferricyanide.

The inorganic base is KOH.

Adopt sodium acetate, sodium carbonate or sodium hydroxide, all can't obtain the flower cluster structure in the present invention, and also can't reach effect among the present invention.

The potassium-doped maghemite-coupled graphene composite combustion catalyst prepared by the above method is K-Fe ₂ O ₃ /G, the crystal form of iron oxide is γ type, and the microscopic appearance is flower cluster.

That is, the catalyst is a flower cluster K-Fe ₂ O ₃ coupled graphene composite (K-Fe ₂ O ₃ /G) assembled by nanoparticles.

This catalyst is used as a combustion catalyst for propellants.

In the present invention, graphene oxide can be self-made or commercialized.

Comparative example 1

Step 1: Weigh 0.248g Fe(NO ₃ ) ₃ 9H ₂ O and dissolve in ethylene glycol solution;

Step 2: Prepare 5mL of 3.5mol/L KOH aqueous solution and add it to the solution obtained in Step 1; stir at room temperature for 15min, then transfer to a 25mL hydrothermal kettle, and keep at 150°C for 12h.

Step 3: The obtained product is washed with deionized water and absolute ethanol, and dried to obtain the final product K-Fe ₂ O ₃ .

Comparative example 2

Step 1: Weigh 0.248g Fe(NO ₃ ) ₃ 9H ₂ O and dissolve in ethylene glycol solution;

Step 2: Prepare 5mL of 3.5mol/L KOH aqueous solution, add it to the system obtained in Step 1 after cooling to room temperature, stir at room temperature for 15min, then transfer to a 25mL hydrothermal kettle, and keep at 160°C for 12h.

Step 3: The obtained product is washed with deionized water and absolute ethanol, and dried to obtain the final product K-Fe ₂ O ₃ .

Example 1

Step 1: Prepare 10 mL of graphene oxide ethylene glycol solution with a concentration of 1 mg/mL;

Step 2: Weigh 0.248g Fe(NO ₃ ) ₃ 9H ₂ O and dissolve it in the graphene oxide solution;

Step 3: Prepare 5 mL of 3.5 mol/L KOH aqueous solution, add it to the mixed solution obtained in Step 2; stir at room temperature for 15 min, then transfer to a 25 mL hydrothermal kettle, and keep at 150°C for 12 h.

Step 4: The obtained product is washed with deionized water and absolute ethanol, and freeze-dried or vacuum-dried to obtain the final product K-Fe ₂ O ₃ /G-1.

Example 2

Step 1: Prepare 10 mL of graphene oxide ethylene glycol solution with a concentration of 2.5 mg/mL;

Step 2: Weigh 0.248g Fe(NO ₃ ) ₃ 9H ₂ O and dissolve it in the graphene oxide solution;

Step 3: Prepare 5mL of 3.5mol/L KOH aqueous solution, stir to dissolve completely, add to the mixed solution obtained in Step 2; stir at room temperature for 15min, then transfer to a 25mL hydrothermal kettle, and keep warm at 150°C for 12h.

Step 4: The obtained product is washed with deionized water and absolute ethanol, and freeze-dried or vacuum-dried to obtain the final product K-Fe ₂ O ₃ /G-2.5.

Fig. 1 is the XRD pattern of the products obtained in Comparative Example 1, Comparative Example 2, Example 1 and Example 2. It can be seen from Figure 1 that the obtained product corresponds to the diffraction peak of γ-form Fe ₂ O ₃ (JCPDS#39-1346), and the intensity of the product diffraction peak is weak due to the low crystallinity of the product.

Fig. 2 and Fig. 3 are TEM images of K-Fe ₂ O ₃ and K-Fe ₂ O ₃ /G prepared in Comparative Example 1 and Example 1, respectively. It can be seen from the TEM image that K-Fe ₂ O ₃ is in the shape of flower clusters and is evenly distributed on the graphene surface. FIG. 4 is the XPS full spectrum of K-Fe ₂ O ₃ prepared in Comparative Example 1. The figure shows that the elements contained in K-Fe ₂ O ₃ include K, Fe and O elements, and the C element is the polluting carbon in the air.

Catalytic Effect Evaluation of Application Example K-Fe ₂ O ₃ /G Nanocomposite

Mix K-Fe ₂ O ₃ , K-Fe ₂ O ₃ /G obtained in Comparative Example 1, Example 1 and Example 2 with the energetic material Octogold (HMX) at a mass ratio of 1:4 and uniformly grind. The prepared mixture was tested by TA differential scanning calorimeter, and the catalytic effect of the prepared sample on the thermal decomposition of energetic materials was analyzed. Test conditions: sample dosage: ~0.2mg; heating rate: 10°C/min; temperature range: 50-300°C; atmosphere: nitrogen atmosphere, gas flow rate: 50mL/min.

It can be seen from Figure 5 that K-Fe ₂ O ₃ and K-Fe ₂ O ₃ /G exhibited different catalytic effects on HMX, which respectively made the initial decomposition temperature and exothermic decomposition temperature of HMX significantly earlier, making the exothermic temperature of HMX The decomposition process changes from melting first and then decomposition to solid decomposition process. Among them, K-Fe ₂ O ₃ /G-2.5 has the most obvious catalytic thermal decomposition effect on HMX. The composite material of the invention can be used as a combustion catalyst of the solid propellant, so as to increase the combustion rate and reduce the pressure index.

Example 3

Step 1: preparing a graphene oxide ethylene glycol solution with a concentration of 2.5 mg/mL;

Step 2: Weigh 0.248g Fe(NO ₃ ) ₃ ·9H ₂ O and dissolve in graphene oxide solution; the mass ratio of graphene oxide to Fe(NO ₃ ) ₃ ·9H ₂ O is 0.1:1.

Step 3: Add 3.5 mol/L KOH aqueous solution to the mixed solution obtained in Step 2, stir at room temperature for 15 min, then transfer to a 25 mL hydrothermal kettle, and keep at 160°C for 12 h. Among them, the mass ratio of graphene oxide to KOH is 0.025:1, and the volume ratio of water to ethylene glycol is 1:2.

Step 4: The obtained product is washed with deionized water and absolute ethanol, and freeze-dried or vacuum-dried to obtain a potassium-doped maghemite-coupled graphene composite combustion catalyst.

Example 4

Step 1: preparing a graphene oxide ethylene glycol solution with a concentration of 1 mg/mL;

Step 2: Weigh 0.248g Fe(NO ₃ ) ₃ ·9H ₂ O and dissolve in graphene oxide solution; the mass ratio of graphene oxide to Fe(NO ₃ ) ₃ ·9H ₂ O is 0.04:1.

Step 3: Add 3.5 mol/L KOH aqueous solution to the mixed solution obtained in Step 2, stir at room temperature for 15 min, then transfer to a 25 mL hydrothermal kettle, and keep warm at 150°C for 10 h. Wherein, the mass ratio of graphene oxide to KOH is 0.01:1, and the volume ratio of water to ethylene glycol is 1:2.

Step 4: The obtained product is washed with deionized water and absolute ethanol, and freeze-dried or vacuum-dried to obtain a potassium-doped maghemite-coupled graphene composite combustion catalyst.

The catalyst prepared by the present invention has the following effects:

It can improve the decomposition efficiency of the main components of the propellant and reduce the sensitivity of the propellant components. Doping a small amount of potassium in the composite catalyst can inhibit the secondary combustion of the combustible gas in the rocket engine nozzle exhaust and reduce the secondary combustion hazard. Reference: RLi, J Wang, J P Shen, et al.Preparation and Characterization of Insensitive HMX/Graphene Oxide Composites[J].PropellantsExplos.Pyrotech.2013,38,798–804; An energetic flame suppressant 1,1'-dihydroxy -3,3'-dinitro-5,5'-bi-1,2,4-triazole dipotassium salt, CN 201518004862.7.

The above are only preferred embodiments in the embodiments of the present invention, so the scope of rights of the present invention cannot be limited by them only, and equivalent changes made according to the claims of the present invention still fall within the scope of the present invention.

Claims (10)

1. The potassium-doped maghemite-coupled graphene composite combustion catalyst is characterized in that graphene oxide, a metal salt precursor and a potassium-containing precipitator are dissolved in a mixed solvent of ethylene glycol and water to carry out hydrothermal reaction, so that the potassium-doped maghemite-coupled graphene composite combustion catalyst is obtained.

2. The potassium-doped maghemite-coupled graphene composite combustion catalyst as claimed in claim 1, wherein the metal salt precursor is Fe (NO) ₃ ·9H ₂ O。

3. The potassium-doped maghemite-coupled graphene composite combustion catalyst as claimed in claim 1, wherein the precipitant is potassium hydroxide.

4. The potassium-doped maghemite-coupled graphene composite combustion catalyst as claimed in claim 1, wherein the solvent is a mixed solvent of water and ethylene glycol in a volume ratio of 1.

5. The potassium-doped maghemite-coupled graphene composite combustion catalyst as claimed in claim 1, wherein the mass ratio of the graphene oxide to the metal salt precursor is 0.04-0.1: 1.

6. the potassium-doped maghemite-coupled graphene composite combustion catalyst according to claim 1, wherein the mass ratio of the graphene oxide to the potassium-containing precipitant is 0.01-0.025: 1.

7. the potassium-doped maghemite-coupled graphene composite combustion catalyst as claimed in claim 1, wherein the dosage ratio of graphene oxide to solvent is 10-25 mg:15mL.

8. The potassium-doped maghemite-coupled graphene composite combustion catalyst as claimed in claim 1, wherein the hydrothermal reaction temperature is 150-160 ℃ and the time is 10-12 h.

9. The potassium-doped maghemite-coupled graphene composite combustion catalyst prepared by the method according to any one of claims 1 to 8, wherein the crystal form of iron oxide in the catalyst is gamma-type, the micro-morphology of the catalyst is in a flower cluster shape, and the catalyst is doped with potassium element.

10. Use of the potassium-doped maghemite-coupled graphene composite combustion catalyst prepared according to any one of claims 1-8 as a combustion catalyst for a propellant in catalyzing the combustion of a solid propellant.

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