Optimized preparation method for synthesizing NTO lead positive salt by sodium salt method

Abstract

The invention relates to an optimized preparation method for synthesizing NTO lead positive salt through a sodium salt method, and belongs to the technical field of burning rate catalysts, solid propellants and energetic materials. According to the method disclosed by the invention, by regulating and controlling synthesis process parameters and applying a crystal form control technology, a crystal form control agent is added in the reaction process of the NTONa2 aqueous solution and the lead nitrate aqueous solution to control the crystal form, so that the NP product with an excellent crystal form is prepared. According to the method, generation of needle-shaped crystal forms is avoided, the physical and chemical stability of NP is improved, the mechanical sensitivity is reduced, and the application performance such as dispersity and filling performance of the NP is remarkably improved. The method is simple and feasible in process, high in safety and suitable for industrial production. The NP product prepared by the method is good in free-running property, narrow in particle size distribution range, high in yield, low in lead hydroxide impurity content and stable in lead content, and has a good application prospect in related technical fields of burning rate catalysts, solid propellants, energetic materials and the like.

Description

[0001] Technical field: The present invention relates to an optimized preparation method of NTO lead salt synthesized by the sodium salt method, wherein sodium hydroxide is reacted with 3-nitro-1,2,4-triazole-5-one (NTO) to synthesize NTO disodium salt, which is then reacted with lead nitrate. The NTO lead salt product is prepared by adjusting the synthesis process parameters and applying the crystal form control technology. The present invention belongs to the technical field of burning rate catalysts, solid propellants, and energetic materials. Background Art

[0002] The rapid development of military technology and the demand for long-range combat have prompted my country to develop long-range, precise, high-speed missiles and other weapon systems with high-energy propulsion units, which in turn put forward strict requirements on the performance of solid propellants, namely the pursuit of higher burning rate, energy density and thrust. As the core power source of solid engines of missiles and other weapons, solid propellants release huge energy and high-temperature gas characteristics during combustion, which directly determines the combat effectiveness and battlefield survivability of weapon systems. Adding burning rate catalysts is one of the most widely used methods to improve the burning rate, a key indicator for measuring the performance of solid propellants. It can not only significantly affect the combustion process of propellants, but also enhance their combustion stability, effectively regulate the pressure index, reduce combustion fluctuations and combustion product emissions, and enable them to achieve platform combustion or Maisai effect within a specific pressure range and reduce damage to the internal structure of the engine. It has always been a hot topic in the field of solid propellant research. Currently, the commonly used burning rate catalysts include five types of burning rate catalysts, namely metal powder catalysts, energetic complex catalysts, inorganic salt catalysts, polymer catalysts and composite catalysts.

[0003] NTO lead salt (NTO-Pb), referred to as NP, is an energetic complex compound burning rate catalyst with high density, rich lead content, high thermal stability, poor water solubility and near-neutral pH value. When added to solid propellants, it can achieve the dual effects of increasing the burning rate and reducing the pressure index without reducing the energy of the solid propellant itself, making it easy to enhance its energy output, stabilize the combustion process, and accurately control the burning rate. Its advantages of high energy density, strong catalytic activity and good compatibility make it widely used in various types of solid propellant formulations, showing great application value.

[0004] The current NP production process often uses NTO and sodium hydroxide to undergo double decomposition to produce NTO disodium salt (NTONa 2 ), and then react with the lead ions in lead nitrate to form yellow NP products. However, during the chemical reaction, due to the molecular characteristics of the compound itself and the technical limitations of the synthesis process, the synthesized crystals mostly present undesirable crystal shapes such as needles, and there are side reactions in the reaction process.

[0005] The current production method of adding liquid is to add lead nitrate solution directly into NTONa 2The NP product is obtained by reaction in the solution, but the hydroxide in the strong alkaline environment of the base solution will compete with the NTO divalent anion, resulting in the presence of lead hydroxide impurities in the NP product. Lead hydroxide, as an ultra-fine and difficult-to-filter material, is mixed in the NP product, which seriously affects the fluidity of the NP product and makes the NP product in a muddy state. The NP product prepared by the above method is needle-shaped, has uneven particle size distribution, poor fluidity, and high sensitivity. The doping of lead hydroxide in it aggravates the agglomeration of the product, which brings a variety of potential risks and hazards to its practical application. Therefore, it is urgent to adjust the technical route and process of NP, optimize its crystal form, reduce the generation of by-products, and solve the technical problems existing in the production and use of NP products.

[0006] In summary, developing an optimized preparation method for NPs with good crystal shape and obtaining an optimized preparation method for NPs with good crystal consistency, few crystal defects, few impurities and high safety is of great significance for the application of NPs in the fields of burning rate catalysts, solid propellants and energetic materials. Summary of the invention

[0007] The present invention is dedicated to solving the potential safety hazards such as the formation of needle-shaped crystals and the generation of lead hydroxide impurities in the NP synthesis process due to the strong alkaline environment. By optimizing the synthesis process and applying the crystal shape control technology, the generation of needle-shaped crystals is avoided and the generation of lead hydroxide impurities is reduced, providing an optimized preparation method for preparing NP by the sodium salt method. The method adjusts the synthesis process parameters and applies the crystal shape control technology. 2 A crystal shape controller is added during the reaction of the aqueous solution and the lead nitrate aqueous solution, thereby preparing a NP product with excellent crystal shape. The method avoids the generation of needle-shaped crystals, not only improves the physical and chemical stability of the NP, reduces the mechanical sensitivity, but also significantly improves its application performance such as dispersibility and packing density. The NP product prepared by the method has good fluidity, a narrow particle size distribution range, a high yield, and a low content of lead hydroxide impurities. Through the implementation of the present invention, the quality and application reliability of the synthesized NP product can be ensured, the process is simple and easy to operate, and the safety is high, which is suitable for industrial production, and provides strong support for the development of related technical fields such as burning rate catalysts, solid propellants, and energetic materials.

[0008] The objectives of the present invention are achieved through the following technical solutions.

[0009] An optimized preparation method for synthesizing NPs by a sodium salt method, the method steps are as follows:

[0010] (1) Preparation of raw material aqueous solution

[0011] Preparation of NTONa 2 The aqueous solution is denoted as NTONa 2 Solution; in NTONa2 In solution, NTONa 2 The mass percentage is 4% to 25%, and the pH value is between 9 and 13.

[0012] An aqueous solution of lead nitrate is prepared, which is referred to as lead nitrate solution. In the lead nitrate solution, the mass percentage of lead nitrate is 5% to 30%, and the pH value is between 2.0 and 4.5.

[0013] An aqueous solution containing a crystal form controller I is prepared, denoted as crystal form controller I. In the crystal form controller solution, the mass percentage of the crystal form controller is 0.1% to 5%, the pH value is adjusted between 5 and 6, and the crystal form controller I is at least one of sodium carboxymethyl cellulose, dextrin and polyacrylamide.

[0014] An aqueous solution containing a crystal shape controller II is prepared, which is recorded as crystal shape controller II. In the crystal shape controller solution, the mass percentage of the crystal shape controller is 0.1% to 5%, and the pH value is adjusted between 5 and 6. The crystal shape controller II is at least one of sodium carboxymethyl cellulose, dextrin and polyacrylamide.

[0015] (2) Chemical Combination Process

[0016] Using lead nitrate solution as the base solution, NTONa 2 The solution is a dropping liquid, and the crystal shape controller I and the crystal shape controller II are all placed in the bottom liquid or in the dropping liquid, or the crystal shape controller I is placed in the bottom liquid / the crystal shape controller II is placed in the dropping liquid, or the crystal shape controller I is placed in the bottom liquid / the crystal shape controller II is placed in the dropping liquid, and NTONa is placed in a constant temperature water bath at 20°C to 80°C and a speed of 200r / min to 800r / min. 2 The solution is added dropwise into the lead nitrate solution for 20 to 80 minutes. After the addition is completed, the reaction is stirred at a constant temperature for 10 to 40 minutes, and then cooled, filtered, washed and dried to obtain a NP product.

[0017] During the experiment, the molar ratio of the NTO lead salt synthesis materials was n(NTO):n(NaOH):n[Pb(NO 3 ) 2 ]=1∶(1.95~2.05):1, the feed ratio is to ensure that the molecular formula of the formed NP is C 2 H 2 N 4 O 4 Pb.

[0018] In addition, NTO 2During the preparation of the solution and the lead nitrate solution, the pH value of the solution is adjusted to the required range by adding dilute nitric acid solution (when the initial pH value of the raw aqueous solution is higher than the required range) or / and 10% sodium hydroxide solution (when the initial pH value of the raw aqueous solution is lower than the required range) to the solution.

[0019] Furthermore, NTO 2 In solution, NTONa 2 The mass fraction is preferably 4% to 20%.

[0020] Furthermore, in the lead nitrate solution, the mass fraction of lead nitrate is preferably 10% to 25%.

[0021] Further, the entire reaction solution system (i.e. NTONa 2 The pH value of the reaction system formed by the solution and the lead nitrate solution is 4-6.

[0022] Furthermore, the crystal shape control agent I and the crystal shape control agent II in the whole product system (ie, NTONa 2 The sum of the mass fractions in the product system obtained by the reaction of the solution and the lead nitrate solution is 0.1% to 0.7%.

[0023] Furthermore, the reaction temperature of the entire reaction system is 20°C to 60°C.

[0024] Furthermore, NTONa 2 The solution is added dropwise to the lead nitrate solution within 20 to 45 minutes to react and generate NP.

[0025] Furthermore, the stirring rate involved in the compounding process is 200 r / min to 800 r / min.

[0026] The NP prepared by the method of the present invention has good application prospects in related technical fields such as energetic materials, burning rate catalysts, solid propellants, etc.

[0027] The beneficial effects of the present invention are as follows:

[0028] (1) The present invention proposes a crystal form optimization preparation method to solve the problems in the synthesis process of NP products, such as the molecular characteristics of the substance itself easily leading to needle-shaped undesirable sensitive crystals and the strong alkaline environment in the reaction system easily generating lead hydroxide impurities. By optimizing process parameters and applying crystal form control technology, the effective regulation of crystal morphology is achieved, thereby significantly improving the crystal form quality of the product and effectively reducing the generation of impurities.

[0029] (2) The method of the present invention has a simple and easy synthetic route, high safety, high NP product yield, and good fluidity, which greatly improves the stability and application performance of the product. It can play a better role in the fields of burning rate catalysts, solid propellants, energetic materials, etc., and has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of the process of preparing NPs according to the present invention;

[0031] Figure 2 It is a physical picture and a microscope picture of the NP product prepared by the present invention;

[0032] Figure 3 These are physical pictures and microscope pictures of NP products prepared without the action of a crystal shape controller and under the action of different crystal shape controllers. DETAILED DESCRIPTION

[0033] The present invention is described below in conjunction with specific embodiments, but the conditions and results described in the implementation do not limit the content and rights of the invention.

[0034] Example 1: Raw materials: NTO (C 2 H 2 N 4 O 4 ), lead nitrate [Pb(NO 3 ) 2 ], sodium hydroxide (NaOH), deionized water (H 2 O), dilute nitric acid (HNO 3 ),dextrin.

[0035] Main instruments and equipment: magnetic stirrer, super constant temperature water bath, measuring cylinder, jacketed beaker, beaker, peristaltic pump, constant temperature drying oven, oil bath pot, pH meter.

[0036] Step 1: Add NTO powder into a beaker, add deionized water according to the stoichiometric ratio, stir to fully suspend NTO in the deionized water, slowly add 10% sodium hydroxide solution according to the stoichiometric ratio in a constant temperature water bath, continue to stir at a constant temperature to dissolve all the suspended NTO and mix well, then add dextrin powder weighed at a ratio of 2.5 per thousand of the product mass ratio, stir to dissolve all the solutes and mix well, and then prepare NTONa. 2 The solution was transferred to a beaker as a drop solution, and the suction end of the peristaltic pump hose was placed in the beaker for standby use. The pH value of the solution was between 11 and 13, where NTONa 2 The mass fraction is 4%.

[0037] Step 2: Add lead nitrate powder into a beaker, add deionized water according to the stoichiometric ratio, stir in a constant temperature water bath to fully dissolve all the solutes and mix them evenly, then add 10% sodium hydroxide solution to adjust the pH value of the solution. The Pb(OH) 2 The white precipitate is removed by filtration to obtain a colorless transparent solution which is placed in a beaker. Then, under continuous stirring, dextrin powder weighed at a ratio of 2.5 thousandths of the product mass ratio is added. The solution is stirred to dissolve all the dextrin and fully mixed for use. The pH value of the solution is between 2.5 and 4.0, and the mass fraction of lead nitrate is 10%.

[0038] Step 3: Add 88 mL of the prepared lead nitrate solution into the jacketed beaker reactor, set the stirring rate to 400 r / min, start the super constant temperature water bath, keep the temperature of the chemical system at 60°C to 75°C, and heat the lead nitrate solution to the water bath temperature.

[0039] Step 4: Start the peristaltic pump and transfer the prepared 123mL NTONa 2 The solution was slowly added dropwise to the lead nitrate solution over 30 min.

[0040] Step 5: Wait for NTONa 2 After the solution was added dropwise, the reaction solution was stirred and reacted for 10 minutes at a constant temperature of 60°C to 75°C, and then the heating was stopped. The reaction system was naturally cooled to room temperature under stirring to generate a yellow NP product. The mother liquor was filtered out, the filtered product was washed, and dried to obtain 81.35g of NP product with a yield of 81.35% and a lead content of 57.2%.

[0041] Example 2: Raw materials: NTO (C 2 H 2 N 4 O 4 ), lead nitrate [Pb(NO 3 ) 2 ], sodium hydroxide (NaOH), deionized water (H 2 O), dilute nitric acid (HNO 3 ), dextrin, polyacrylamide.

[0042] Main instruments and equipment: magnetic stirrer, super constant temperature water bath, measuring cylinder, jacketed beaker, beaker, peristaltic pump, constant temperature drying oven, oil bath pot, pH meter.

[0043] Step 1: Add NTO powder to a beaker, add deionized water measured according to the stoichiometric ratio, stir to fully suspend NTO in the deionized water, slowly add 10% sodium hydroxide solution measured by mole ratio under constant temperature water bath stirring conditions, continue constant temperature stirring to completely dissolve the suspended NTO and fully mix, then add dextrin powder weighed at a ratio of 0.3% of the product mass ratio and 2mL of the prepared 0.1% polyacrylamide solution, stir to dissolve all the solutes and fully mix, and then prepare NTONa 2 The solution was transferred to a beaker as a drop solution, and the suction end of the peristaltic pump hose was placed in the beaker for standby use. The pH value of the solution was between 11 and 13. 2 The mass fraction is 15%.

[0044] Step 2: Add lead nitrate powder into a beaker, add deionized water according to the stoichiometric ratio, stir in a constant temperature water bath to fully dissolve all the solutes and mix them evenly, then add 10% sodium hydroxide solution to adjust the pH value of the solution. The Pb(OH) 2 The white precipitate is removed by filtration to obtain a colorless transparent solution which is placed in a beaker. Then, under continuous stirring conditions, dextrin powder weighed at a ratio of 0.3% of the mass ratio of the product and 2 mL of the prepared 0.1% polyacrylamide solution are added. The dextrin is stirred to completely dissolve and fully mixed for use. The pH value of the solution is between 2.5 and 4.0, and the mass fraction of lead nitrate is 20%.

[0045] Step 3: Add 40 mL of the prepared lead nitrate solution into the jacketed beaker reactor, set the stirring rate to 400 r / min, start the super constant temperature water bath, keep the temperature of the chemical system at 50°C to 60°C, and heat the lead nitrate solution to the water bath temperature.

[0046] Step 4: Start the peristaltic pump and transfer the prepared 34mL NTONa 2 The solution was slowly added dropwise to the lead nitrate solution over 30 min.

[0047] Step 5: Wait for NTONa 2 After the solution was added dropwise, the reaction solution was stirred and reacted for 10 minutes at a constant temperature of 50°C to 60°C, and then the heating was stopped. The reaction system was naturally cooled to room temperature under stirring to generate a yellow NP product. The mother liquor was then filtered out, the filtered product was washed, and dried to obtain 8.57g of NP product with a yield of 85.7% and a lead content of 57%.

[0048] Example 3: Raw materials: NTO (C 2 H 2 N 4 O4 ), lead nitrate [Pb(NO 3 ) 2 ], sodium hydroxide (NaOH), deionized water (H 2 O), dilute nitric acid (HNO 3 ), dextrin, polyacrylamide.

[0049] Main instruments and equipment: magnetic stirrer, super constant temperature water bath, measuring cylinder, jacketed beaker, beaker, peristaltic pump, constant temperature drying oven, oil bath pot, pH meter, flask.

[0050] Step 1: Add sodium hydroxide solid in a stoichiometric ratio into a beaker, add deionized water in a stoichiometric ratio, stir to fully dissolve the sodium hydroxide, wait for the sodium hydroxide aqueous solution to cool to a constant temperature water bath condition, slowly add NTO powder in a molar stoichiometric ratio under stirring, continue to stir at a constant temperature to dissolve all the NTO powder and fully mix it, then add crystal form control agent I (dextrin powder) weighed at a ratio of 0.3% of the product mass ratio and 2mL of the obtained crystal form control agent II (0.1% polyacrylamide solution), stir to dissolve all the solutes and fully mix them, and then configure NTONa 2 The solution was transferred to a beaker as a drop solution, and the suction end of the peristaltic pump hose was placed in the beaker for standby use. The pH value of the solution was between 11 and 13, where NTONa 2 The mass fraction is 15%.

[0051] Step 2: Add lead nitrate powder into a beaker, add deionized water according to the stoichiometric ratio, stir in a constant temperature water bath to fully dissolve all the solutes and mix them evenly, then add 10% sodium hydroxide solution to adjust the pH value of the solution. The Pb(OH) 2 The white precipitate is removed by filtration to obtain a colorless transparent solution which is placed in a beaker. Then, under continuous stirring, a crystal form control agent I (dextrin powder) weighed at a ratio of 0.3% of the mass ratio of the product and 2 mL of the prepared crystal form control agent II (0.1% polyacrylamide solution) are added. The solution is stirred to dissolve all the solutes and fully mixed for use. The pH value of the solution is between 2.5 and 3.5, and the mass fraction of lead nitrate is 20%.

[0052] Step 3: Add 40 mL of the prepared lead nitrate solution into the jacketed beaker reactor, set the stirring rate to 400 r / min, start the super constant temperature water bath, keep the temperature of the chemical system at room temperature, and heat the lead nitrate solution to the water bath temperature.

[0053] Step 4: Start the peristaltic pump and transfer the prepared 34mL NTONa 2 The solution was slowly added dropwise to the lead nitrate solution within 20 min.

[0054] Step 5: Wait for NTONa 2 After the solution was added dropwise, the reaction solution was stirred and reacted for 5 minutes at a constant temperature, and then the heating was stopped to generate a yellow NP product. The mother liquor was filtered out, the filtered product was washed, and dried to obtain 9.03g of NP product with a yield of 90.3% and a lead content of 57%.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein, and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optimized preparation method for synthesizing NTO lead salt by sodium salt method, characterized in that: The method steps are as follows: (1) Preparation of raw material aqueous solution Prepare an aqueous solution of NTONa2, recorded as NTONa2 solution; in the NTONa2 solution, the mass percentage of NTONa2 is 4% to 25%, and the pH value is between 9 and 13; prepare an aqueous solution of lead nitrate, recorded as lead nitrate solution; in the lead nitrate solution, the mass percentage of lead nitrate is 5% to 30%, and the pH value is between 2.0 and 4.5; prepare an aqueous solution containing a crystal shape controller I, recorded as crystal shape controller I, in the crystal shape controller solution, the mass percentage of the crystal shape controller is 0.1% to 5%, the pH value is adjusted between 5 and 6, and the crystal shape controller I is at least one of sodium carboxymethyl cellulose, dextrin and polyacrylamide; prepare an aqueous solution containing a crystal shape controller II, recorded as crystal shape controller II, in the crystal shape controller solution, the mass percentage of the crystal shape controller is 0.1% to 5%, the pH value is adjusted between 5 and 6, and the crystal shape controller II is at least one of sodium carboxymethyl cellulose, dextrin and polyacrylamide. (2) Chemical Combination Process Lead nitrate solution is used as base liquid and NTONa2 solution is used as drop liquid. Crystal form controller I and crystal form controller II are all placed in base liquid or drop liquid, or crystal form controller I is placed in base liquid / crystal form controller II is placed in drop liquid, or crystal form controller I is placed in base liquid / crystal form controller II is placed in drop liquid, NTONa2 solution is added dropwise to lead nitrate solution in a constant temperature water bath of 20°C to 80°C and a rotation speed of 200r / min to 800r / min, the dropwise addition time is 20min to 80min, after the dropwise addition is completed, the reaction is stirred at a constant temperature for 10min to 40min, cooled, filtered, washed and dried to obtain NP product. The molar ratio of the synthetic materials of NTO lead salt is n(NTO):n(NaOH):n[Pb(NO3)2]=1:(1.95-2.05):1, and the feed ratio is to ensure that the molecular formula of the formed NP is C2H2N4O4Pb.

2. The method according to claim 1, characterized in that: The total mass proportion of the crystal shape control agent in the product system obtained by the chemical reaction is 0.1% to 0.7%.

3. The method according to claim 1, characterized in that: The crystal shape controlling agent is at least one of sodium carboxymethyl cellulose, dextrin and polyacrylamide.

4. The method according to claim 1, characterized in that: The method for adding the crystal shape controller is to place both the crystal shape controller I and the crystal shape controller II in the base liquid or in the dropping liquid or to place the crystal shape controller I in the base liquid and the crystal shape controller II in the dropping liquid or to place the crystal shape controller I in the base liquid and the crystal shape controller II in the dropping liquid.

5. The method according to claim 1, characterized in that: The temperature of the reaction system is controlled at 20°C to 80°C, the pH value of the reaction system is controlled at 4 to 6, the stirring rate is controlled at 200 r / min to 800 r / min, the dropping time is controlled at 20 min to 80 min, and the molar ratio of the synthetic materials is n(NTO):n(NaOH):n[Pb(NO3)2]=1:(1.95 to 2.05):

1.

6. The method according to claim 1, characterized in that: In the NTONa2 solution, the mass fraction of NTONa2 is preferably 4% to 25%; in the lead nitrate solution, the mass fraction of lead nitrate is preferably 5% to 30%.

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