Process for the catalytic thermal decomposition of ammonium perchlorate using metal carbodiimide compounds

Abstract

The application discloses a method for catalyzing thermal decomposition of ammonium perchlorate by using a metal carbodiimide compound, and belongs to the field of solid rocket propellants. The method is characterized in that the metal carbodiimide compound is mixed into the ammonium perchlorate at a certain proportion and used as a catalyst to perform a thermal decomposition reaction of the ammonium perchlorate, so as to reduce the thermal decomposition temperature of the ammonium perchlorate and improve the heat release. Therefore, the method can be applied to the field of solid rocket propellants.

Description

Technical Field

[0001] This invention belongs to the field of solid rocket propellants, specifically relating to a method for using a metal carbodiimide compound to catalyze the thermal decomposition of ammonium perchlorate. Background Technology

[0002] Solid rocket motors offer numerous advantages, including unrestricted launch environments, pre-loading of propellants, high reliability, and high power, making them the propulsion source for tactical and strategic rocket weapons. Solid propellants, as the power-providing component, are complex systems composed of oxidizers, fuels, binders, plasticizers, antioxidants, and bonding agents. The decomposition and combustion characteristics of the energy components, represented by the oxidizer, directly affect the overall combustion performance of the solid propellant. Ammonium perchlorate (AP) is currently the most common oxidizer in solid propellants, and its thermal decomposition behavior significantly impacts the overall performance of the solid propellant. Typically, controlling the initial decomposition temperature of AP using submicron or nano-sized particles and adding catalysts is an effective method.

[0003] There are many types of catalysts used in the thermal decomposition of ammonium perchlorate in the prior art, such as those disclosed in invention patents CN115677432A, CN 115894137A, CN 114890851A, CN 115739185A, CN 114436722A, including metal complexes, metal oxides, and transition metal compounds.

[0004] Metal carbodiimide compounds are a new type of oxochalcogenide-like compound—transition metal carbodiimides, also known as metal cyanamide compounds M. x (NCN) y (Where M represents an alkali metal, alkaline earth metal, transition metal, or nonmetal element), due to its unique electronic structure and novel physicochemical properties, it has gradually become a research hotspot. [NCN] 2- It exhibits linear and conjugated characteristics, similar to the VIA family O 2- and S 2- Similar to the anions, its transition metal cyanamide salt can be considered as a nitrogen-based analog of its oxide counterpart; due to the weaker electronegativity of C and N, [NCN]... 2- The overall electronegativity of the anionic group is weaker than that of O. 2- The transition metal cyanamide compounds have weaker covalent properties than their homologous oxides, resulting in stronger metastable characteristics and chemical reactivity in transition metal cyanamide salts. However, there are currently no reports on the use of carbodiimides for the thermal decomposition of ammonium perchlorate. Summary of the Invention

[0005] To address the shortcomings of existing preparation techniques, this invention provides a method for using metal carbodiimide compounds to catalyze the thermal decomposition of ammonium perchlorate.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A method for using a metal carbodiimide compound to catalyze the thermal decomposition of ammonium perchlorate involves incorporating the metal carbodiimide compound into ammonium perchlorate in a certain proportion as a catalyst to carry out the thermal decomposition reaction of ammonium perchlorate, thereby achieving the purpose of reducing the thermal decomposition temperature and increasing the heat release.

[0008] Specifically, it includes the following steps:

[0009] (1) Add ZnCl2·2H2O and H2NCN to a round-bottom flask and dissolve them in deionized water;

[0010] (2) Then, dissolve Na2SO3 in deionized water, stir thoroughly, and add it to the solution in step (1);

[0011] (3) Finally, in step (2), a concentrated ammonia solution (25 wt.%) is added to adjust the pH to about 10, and a precipitate will appear;

[0012] (4) After the suspension was stirred overnight, the intermediate product was slowly oxidized by atmospheric oxygen at room temperature to generate a white product. After filtration and separation, washing with water, and vacuum drying at 60°C for 12 hours, ZnNCN (metal carbodiimide compound) was finally obtained.

[0013] (5) Weigh the synthesized ZnNCN and ammonium perchlorate (AP) and place them in a container. Add anhydrous ethanol, sonicate at room temperature for 10 min, and vacuum dry at 50℃ for 12 h.

[0014] (6) In an argon atmosphere, the heating rate is 20K / min to complete the thermal decomposition process.

[0015] Furthermore, in step (1), the molar ratio of ZnCl2·2H2O and H2NCN is 1:2.

[0016] Furthermore, the molar ratio of Na2SO3 to ZnCl2·2H2O added in step (2) is 1:1.

[0017] Furthermore, the amount of the metal carbodiimide compound incorporated is 3-5% of the mass of ammonium perchlorate, more preferably 4%.

[0018] The beneficial effects of this invention are:

[0019] The key point of this invention is to develop a method for applying a metal carbodiimide compound to catalyze the thermal decomposition of ammonium perchlorate, providing a new approach for the application of other types of oxides in thermal catalysis. The overall effect is that, with a doping amount of 4% metal carbodiimide compound, the thermal decomposition temperature of ammonium perchlorate can be reduced by 80°C and the heat release can be increased by 477 J / g. Attached Figure Description

[0020] The invention will now be further described with reference to the accompanying drawings.

[0021] Figure 1 This is the X-ray diffraction pattern of ZnNCN obtained in Example 1 of this invention;

[0022] Figure 2 This is a scanning electron microscope image of ZnNCN prepared in Example 1 of the present invention;

[0023] Figure 3 This is the DSC diagram of pure AP and AP+4% ZnNCN in Embodiment 1 of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] (1) Add 10 mmol ZnCl2·2H2O and 20 mmol H2NCN to a round-bottom flask and dissolve them in 5 mL of deionized water;

[0027] (2) Then, dissolve 10 mmol Na2SO3 in 5 mL of deionized water, stir thoroughly, and add it to the solution in step (1);

[0028] (3) Finally, in step (2), a concentrated ammonia solution (25 wt.%) is added to adjust the pH to about 10, and a precipitate will appear;

[0029] (4) After stirring the suspension overnight, the intermediate product was slowly oxidized by atmospheric oxygen at room temperature to produce a white product. After filtration, washing with water, and vacuum drying at 60°C for 12 hours, ZnNCN was finally obtained. The composition and morphology of the synthesized product are characterized as follows: Figure 1 and Figure 2 As shown;

[0030] (5) Weigh 0.4g of synthesized ZnNCN and 10g of ammonium perchlorate (AP) into a beaker, add about 5mL of anhydrous ethanol, sonicate at room temperature for 10min, and vacuum dry at 50℃ for 12h.

[0031] (6) Under an argon atmosphere, at a heating rate of 20 K / min, the DSC thermal decomposition patterns of pure AP and AP + 4% ZnNCN were compared and tested. The results are as follows: Figure 3 As shown.

[0032] As shown in the figure, the thermal decomposition temperature of ammonium perchlorate can be reduced by 80°C by incorporating 4% ZnNCN, and its heat release can be increased by 477 J / g.

[0033] The above detailed embodiments provide a specific description of the analytical methods involved in this invention. It should be noted that the above description is only intended to help those skilled in the art better understand the methods and ideas of this invention, and is not intended to limit the scope of the invention. Without departing from the principles of this invention, those skilled in the art can make appropriate adjustments or modifications to this invention, and such adjustments and modifications should also fall within the protection scope of this invention.

Claims

1. A method for using metal carbodiimide compounds to catalyze the thermal decomposition of ammonium perchlorate, characterized in that, The thermal decomposition reaction of ammonium perchlorate was carried out by incorporating a metal carbodiimide compound into ammonium perchlorate in a certain proportion as a catalyst. The amount of the metal carbodiimide compound incorporated is 3-5% of the mass of ammonium perchlorate.

2. The method for using the metal carbodiimide compound according to claim 1 to catalyze the thermal decomposition of ammonium perchlorate, characterized in that, The amount of the metal carbodiimide compound incorporated is 4% of the mass of ammonium perchlorate.

3. The method for using the metal carbodiimide compound according to claim 2 to catalyze the thermal decomposition of ammonium perchlorate, characterized in that, When the amount of the metal carbodiimide compound incorporated is 4%, the thermal decomposition temperature of ammonium perchlorate is reduced by 80°C, and the heat release is increased by 477 J / g.

4. The method for using the metal carbodiimide compound according to claim 1 to catalyze the thermal decomposition of ammonium perchlorate, characterized in that, The metal carbodiimide compound was prepared by precipitation.

Images