A porous basic copper nitrate and a preparation method and application thereof

Abstract

The application provides a porous basic copper nitrate and a preparation method and application thereof. The preparation method of the porous basic copper nitrate comprises the following steps: taking styrene as a monomer, obtaining polystyrene microspheres with a uniform and compact packing structure through an emulsion synthesis method and continuous slow centrifugation, adding the polystyrene microspheres into a copper nitrate solution containing a dispersant, performing vacuum treatment under normal temperature conditions, obtaining a precursor filled with copper ions after centrifugal separation, dispersing the precursor in water, introducing ammonia gas to perform an in-situ precipitation reaction under stirring, obtaining polystyrene microspheres filled with basic copper nitrate after filtration, removing a template through organic solvent washing, and obtaining the porous basic copper nitrate after drying treatment. The application uses the uniform and compact PS ball as a template, combines with an ammonia gas precipitation method, realizes limited growth of the basic copper nitrate under mild conditions, and thus constructs an ordered porous structure. The prepared porous basic copper nitrate has the advantages of high purity, good flowability, uniform particles, large specific surface area and good combustion performance.

Description

Technical Field

[0001] This invention relates to the field of functional materials preparation technology, specifically to a porous basic copper nitrate, its preparation method, and its application. Background Technology

[0002] Basic copper nitrate (BCN) is an excellent oxidant with an effective oxygen content of up to 30%, good thermal stability, and advantages such as high gas production rate, low enthalpy of formation, low hygroscopicity, and easy filtration of combustion residue. It is often used in combination with guanidine nitrate to form the core formula of automotive airbag gas generators.

[0003] With the rapid development of the automotive industry, higher requirements have been placed on the safety and stability of airbag initiators, leading to increasingly stringent quality requirements for basic copper nitrate (BCN). Research indicates that many properties and applications of BCN are closely related to its specific surface area. A larger specific surface area and more active sites help improve the effective contact and collision between basic BCN and other functional components, while also achieving better adsorption and conversion of combustion reaction intermediates, further enhancing the reaction rate and combustion rate. The traditional synthesis method for BCN involves co-precipitation of copper nitrate and sodium hydroxide. During the reaction, variations in sodium hydroxide concentration and dropping rate can result in locally excessively high or low alkali concentrations in the reaction system, unstable pH values, and less than ideal product morphology. Theoretically, smaller BCN particle size, larger specific surface area, and more reactive active sites are more conducive to improving combustion speed. Current methods modify the BCN synthesis process by changing reaction conditions to obtain nanoscale BCN with even smaller particle sizes. However, some improved methods require complex and cumbersome reaction steps, high reaction temperatures, long reaction times, or special equipment (such as autoclaves or plasma reactors). Furthermore, nanoscale BCN with excessively small dimensions may lead to agglomeration, which in turn affects the reaction rate.

[0004] In conclusion, obtaining basic copper nitrate with high purity, good flowability, uniform particle size, large specific surface area, and good combustion performance is of great significance for promoting its application in the fields of catalysis and energetic materials. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a porous basic copper nitrate, its preparation method and application, aiming to solve the technical problems of easy agglomeration and poor combustion performance of existing nano-sized basic copper nitrate.

[0006] In a first aspect, the present invention provides a method for preparing porous basic copper nitrate, comprising the following steps: S1. Monodisperse polystyrene microspheres were prepared by emulsion synthesis using styrene as a monomer, and polystyrene microspheres with a uniform and tightly packed structure were obtained by continuous slow centrifugation. S2. Polystyrene microspheres with a uniform and tightly packed structure are added to a copper nitrate solution containing a dispersant, and vacuum treatment is carried out at room temperature. After centrifugation, a precursor filled with copper ions is obtained. S3. Disperse the copper ion-filled precursor in water, introduce ammonia gas under stirring to carry out in-situ precipitation reaction, and obtain polystyrene microspheres filled with basic copper nitrate after filtration. S4. Polystyrene microspheres filled with basic copper nitrate are washed with an organic solvent to remove the hard template of the polystyrene microspheres, and then dried to obtain porous basic copper nitrate.

[0007] Preferably, in step S1, the speed of slow centrifugation is 2000~4000 r / min; the time of slow centrifugation is 10~14h.

[0008] Preferably, step S1 specifically involves: dispersing styrene in water, purging with nitrogen to remove air, adding an initiator at 60-75°C, and after polymerization for 12-24 hours, centrifuging slowly at 2000-4000 r / min for 10-14 hours, followed by vacuum drying to obtain polystyrene microspheres with a uniform and tightly packed structure.

[0009] Preferably, in step S2, the mass ratio of the uniformly and tightly packed polystyrene microspheres to copper nitrate is (1~3):1.

[0010] Preferably, in step S2, the solvent for the copper nitrate solution is ethanol and / or water; the concentration of copper nitrate in the copper nitrate solution is 20~100g / L; and the concentration of dispersant in the copper nitrate solution is 10~50g / L.

[0011] Preferably, in step S2, the dispersant includes at least one of polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol.

[0012] Preferably, in step S3, the rate of ammonia gas introduction is 60~150 mL / min; the amount of ammonia gas introduced is 1.5~2.5 times the molar amount of copper nitrate in the copper nitrate solution; the temperature of the in-situ precipitation reaction is 20~45℃, and the time of the in-situ precipitation reaction is 3~8h.

[0013] Preferably, in step S4, the organic solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, dichloromethane, and acetone.

[0014] In a second aspect, the present invention provides a porous basic copper nitrate, which is prepared by the preparation method described in the first aspect.

[0015] Thirdly, the present invention provides a gas generator, the raw materials for which include guanidine nitrate, porous basic copper nitrate, and a catalyst.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The porous basic copper nitrate provided by the present invention makes full use of the template effect of the uniformly densely packed PS spheres to realize the in-situ confined generation of BCN in the densely packed pores of the spheres, constructs a porous structure, increases the specific surface area of ​​BCN, exposes more active sites, facilitates the subsequent composite of BCN and gas-generating agent guanidine nitrate, and promotes better adsorption and conversion of reaction intermediates, greatly improving the combustion rate.

[0017] (2) The method for preparing porous basic copper nitrate provided by the present invention adds a dispersant to the copper nitrate solution, which on the one hand avoids the aggregation and adhesion of PS single spheres, and on the other hand can effectively enhance the binding ability of the PS sphere surface to copper ions, promote the copper ion loading process, and can be easily removed by washing later.

[0018] (3) The method for preparing porous basic copper nitrate provided by the present invention selects ammonia as the alkali source in the in-situ confined synthesis of basic copper nitrate. On the one hand, its alkalinity is relatively weak, which can avoid the excessive concentration of local hydroxide ions in the solution and the generation of copper hydroxide. At the same time, it can prevent the precipitation reaction rate from being too fast and causing excessive structural stress, which would destroy the porous structure formed by the hard template method. It also avoids the swelling and deformation of the PS ball hard template in the strong alkaline solution. On the other hand, by constructing NH3-NH4 + Buffer solution system, to promptly eliminate OH in localized areas - The concentration gradient provides a stable solution environment for the formation of new crystals and their regular growth.

[0019] (4) The preparation method provided by the present invention uses readily available raw materials, simple equipment, and easy operation. The resulting porous basic copper nitrate has uniform particle size, high purity, good dispersibility, large specific surface area, and excellent combustion performance. Attached Figure Description

[0020] Figure 1 The image shows the XRD pattern of porous basic copper nitrate synthesized in Example 1 of this invention. Figure 2 This is a transmission electron microscope image of the porous basic copper nitrate synthesized in Example 1 of the present invention; Figure 3 This is a particle size distribution test diagram of the porous basic copper nitrate synthesized in Example 1 of the present invention; Figure 4 The burst test curve of porous basic copper nitrate synthesized in Example 1 of this invention; Figure 5 This is a schematic diagram of the preparation process of porous basic copper nitrate according to the present invention. Detailed Implementation

[0021] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0022] To address the technical problems of easy agglomeration and poor combustion performance of existing nano-sized basic copper nitrate, this invention provides a porous basic copper nitrate, its preparation method, and its application. By using uniformly packed PS spheres as templates and combining them with ammonia precipitation, basic copper nitrate is grown in a confined space under mild conditions, thereby constructing an ordered porous structure and obtaining basic copper nitrate with high purity, good flowability, uniform particle size, large specific surface area, and good combustion performance.

[0023] In a first aspect, embodiments of the present invention provide a method for preparing porous basic copper nitrate, comprising the following steps: S1. Monodisperse polystyrene microspheres were prepared by emulsion synthesis using styrene as a monomer, and polystyrene microspheres with a uniform and tightly packed structure were obtained by continuous slow centrifugation. S2. Polystyrene microspheres with a uniform and tightly packed structure are added to a copper nitrate solution containing a dispersant, and vacuum treatment is carried out at room temperature. After centrifugation, a precursor filled with copper ions is obtained. S3. Disperse the copper ion-filled precursor in water, introduce ammonia gas under stirring to carry out in-situ precipitation reaction, and obtain polystyrene microspheres filled with basic copper nitrate after filtration. S4. Polystyrene microspheres filled with basic copper nitrate are washed with an organic solvent to remove the hard template of the polystyrene microspheres, and then dried to obtain porous basic copper nitrate.

[0024] In the technical solution of this invention, uniformly sized monodisperse polystyrene microspheres (PS spheres) are used as a hard template. A tightly packed structure is obtained through continuous slow centrifugation. Then, a copper nitrate solution containing a dispersant is vacuum impregnated into the gaps between the PS spheres to obtain a precursor complex filled with copper ions. Ammonia gas is then introduced to conduct a confined reaction, generating basic copper nitrate in situ. Finally, the template is gently removed using an organic solvent, and the product is washed and vacuum dried to obtain an ordered porous basic copper nitrate structure. The addition of a dispersant to the copper nitrate solution prevents the aggregation and adhesion of PS spheres and effectively enhances the binding capacity of the PS sphere surface for copper ions, promoting the copper ion loading process. This dispersant can be easily removed by washing. Vacuum impregnation effectively removes air adsorbed in the gaps between the PS microspheres and on their surface, eliminating air resistance that hinders the penetration of the precursor solution. Under negative pressure, the filling efficiency and wettability of the copper ion solution in the PS sphere gaps are significantly improved, promoting the full adsorption and uniform distribution of copper ions on the template surface, laying the foundation for the subsequent in-situ generation of basic copper nitrate. In the in-situ confined synthesis of basic copper nitrate, ammonia was chosen as the alkali source. Firstly, its weak alkalinity avoids excessively high local hydroxide concentrations in the solution, preventing the formation of copper hydroxide. Secondly, it prevents excessively rapid precipitation reactions that could cause excessive structural stress, damaging the porous structure formed by the hard template method, and also avoids the swelling and deformation of the PS sphere hard template in strongly alkaline solutions. Thirdly, by constructing NH3-NH4... + Buffer solution system, to promptly eliminate OH in localized areas - The concentration difference quickly returns to the average level of the solution, providing a stable solution environment for the formation of new crystals and regular growth.

[0025] Furthermore, in some embodiments, in step S1, the rotation speed of the slow centrifugation is 2000~4000 r / min; the slow centrifugation time is 10~14 h.

[0026] Further, in some embodiments, step S1 specifically involves: dispersing styrene in water, purging with nitrogen to remove air, adding an initiator at 60-75°C, performing a polymerization reaction for 12-24 hours, centrifuging slowly at 2000-4000 r / min for 10-14 hours, and then vacuum drying to obtain polystyrene microspheres with a uniform and tightly packed structure.

[0027] Furthermore, in some embodiments, the styrene is styrene that has been washed with an aqueous NaOH solution.

[0028] In the technical solution of this invention embodiment, washing with NaOH aqueous solution can remove the stabilizer hydroquinone present in styrene, which facilitates the subsequent polymerization of styrene.

[0029] Furthermore, in some embodiments, the initiator includes at least one of potassium persulfate and ammonium persulfate.

[0030] Furthermore, in some embodiments, the amount of initiator used is 0.5% to 2% of the mass of styrene.

[0031] Furthermore, in some embodiments, in step S2, the mass ratio of the uniformly and densely packed polystyrene microspheres to copper nitrate is (1~3):1.

[0032] Furthermore, in some embodiments, in step S2, the solvent for the copper nitrate solution is ethanol and / or water.

[0033] Furthermore, in some embodiments, in step S2, the concentration of copper nitrate in the copper nitrate solution is 20~100g / L; the concentration of dispersant in the copper nitrate solution is 10~50g / L.

[0034] Furthermore, in some embodiments, in step S2, the dispersant includes at least one of polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol.

[0035] Furthermore, in some embodiments, the vacuum treatment time in step S2 is 1 to 6 hours.

[0036] In the technical solution of this invention embodiment, under vacuum conditions, PS spheres and a dispersant are added to Cu. 2+ The precursor copper ions fill the voids in the PS spheres in the solution. Vacuum treatment effectively removes air adsorbed in the gaps between the PS microspheres and on their surface, eliminating air resistance that hinders the penetration of the precursor solution. Under negative pressure, the filling efficiency and wettability of the copper ion solution in the PS sphere voids are significantly improved, promoting the full adsorption and uniform distribution of copper ions on the template surface, laying the foundation for the subsequent in-situ generation of basic copper nitrate. During this process, tiny bubbles are observed to form on the surface of the PS spheres, and the PS spheres gradually turn blue, indicating that the copper nitrate solution gradually enters the channels of the stacked PS spheres under vacuum.

[0037] Furthermore, in some embodiments, in step S3, the rate at which ammonia gas is introduced is 60~150 mL / min.

[0038] Furthermore, in some embodiments, in step S3, the amount of ammonia gas introduced is 1.5 to 2.5 times the molar amount of copper nitrate in the copper nitrate solution.

[0039] Furthermore, in some embodiments, in step S3, the temperature of the in-situ precipitation reaction is 20~45°C, and the time of the in-situ precipitation reaction is 3~8 h.

[0040] Furthermore, in some embodiments, in step S4, the organic solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, dichloromethane, and acetone.

[0041] Furthermore, in some embodiments, the drying process in step S4 is spray drying.

[0042] Secondly, embodiments of the present invention provide a porous basic copper nitrate, which is prepared by the preparation method described in the first aspect.

[0043] Thirdly, embodiments of the present invention provide a gas generator, the raw materials for which include guanidine nitrate, porous basic copper nitrate, and a catalyst.

[0044] In the technical solution of this invention embodiment, the porous structure of basic copper nitrate provided by this invention can achieve good compatibility with the gas-generating agent guanidine nitrate and greatly improve the combustion rate, thus meeting the application requirements of automotive airbags.

[0045] Furthermore, in some embodiments, the mass ratio of guanidine nitrate, porous basic copper nitrate, and catalyst is 50:43:7.

[0046] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0047] Example 1 Figure 5 Please refer to the schematic diagram of the preparation process of porous basic copper nitrate. Figure 5 This embodiment provides a method for preparing porous basic copper nitrate, the specific steps of which are as follows: (1) Preparation of PS sphere hard template: 90 mL of styrene was measured and poured into a separatory funnel. It was washed twice with 10% NaOH solution and distilled water to remove the stabilizer hydroquinone from the styrene. 250 mL of distilled water was added to a 500 mL flask. Then, the washed styrene was added to the flask and bubbled with N2 for 15 min to fully purge the air from the system. The reaction was stirred at 75 °C for 30 min. Then, 25 mL of an aqueous solution containing 0.50 g of K2S2O8 (initiator) was quickly added. The reaction was continued at this temperature for 24 h. The reaction solution was centrifuged at 2000 r / min for 10 h. The supernatant was discarded and the solution was dried under vacuum to obtain a uniformly densely packed PS sphere hard template.

[0048] (2) Preparation of copper ion-filled precursor: 4.00 g polyvinylpyrrolidone (PVP, K30), 10.00 g copper nitrate (Cu(NO3)2·3H2O), 100 mL distilled water and 100 mL ethanol were added sequentially to a 500 mL beaker. After sonication until completely dissolved, 10.00 g polystyrene (PS) spheres were added. The beaker was then placed in a vacuum drying oven and vacuum-treated at room temperature for 1 h to ensure the solution fully filled the pore structure of the PS spheres. After treatment, the beaker was removed and the supernatant was removed by centrifugation to obtain the copper ion-filled precursor, which was named PS@Cu. 2+ .

[0049] (3) In-situ confined synthesis of basic copper nitrate: The above-mentioned precursor filled with copper ions was dispersed in distilled water (the ratio of precursor to distilled water was 1g / 20mL). Ammonia gas was introduced under stirring, and the ammonia gas introduction rate was controlled by a flow meter to be 100 mL / min and the introduction time was 20 min. The in-situ precipitation reaction was carried out at room temperature for 4 h to generate basic copper nitrate. After removing the supernatant, PS spheres filled with BCN were obtained.

[0050] (4) Template removal: DMF, which has good solubility for PS balls, was used as a solvent. The PS template was removed by soaking and washing three times with DMF. The crude product was obtained by centrifugation. The crude product was washed alternately with deionized water and ethanol until neutral. After spray drying, porous basic copper nitrate was obtained.

[0051] Example 2 A method for preparing porous basic copper nitrate, the specific steps of which are as follows: (1) Preparation of PS ball hard template: Same as in Example 1.

[0052] (2) Preparation of copper ion-filled precursor: 5.00 g of polyvinylpyrrolidone (PVP, K30), 10.00 g of copper nitrate (Cu(NO3)2·3H2O), 100 mL of distilled water and 100 mL of ethanol were added sequentially to a 500 mL beaker. After sonication until completely dissolved, 10.00 g of polystyrene (PS) spheres were added. The beaker was then placed in a vacuum drying oven and vacuum-treated at room temperature for 1 h to ensure that the solution fully filled the pore structure of the PS spheres. After treatment, the beaker was removed and the supernatant was removed by centrifugation to obtain the copper ion-filled precursor, which was named PS@Cu. 2+ .

[0053] (3) In-situ confined synthesis of basic copper nitrate: The above-mentioned precursor filled with copper ions was dispersed in distilled water (the ratio of precursor to distilled water was 1g / 20mL). Ammonia gas was introduced under stirring, and the ammonia gas introduction rate was controlled by a flow meter to be 100 mL / min and the introduction time was 20 min. The in-situ precipitation reaction was carried out at 40℃ for 4h to generate basic copper nitrate. After removing the supernatant, PS spheres filled with BCN were obtained. (4) Template removal: DMF, which has good solubility for PS balls, was used as a solvent. The PS template was removed by soaking and washing three times with DMF. The crude product was obtained by centrifugation. The crude product was washed alternately with deionized water and ethanol until neutral. After spray drying, porous basic copper nitrate was obtained.

[0054] Example 3 A method for preparing porous basic copper nitrate, the specific steps of which are as follows: (1) Preparation of PS ball hard template: Same as in Example 1.

[0055] (2) Preparation of copper ion-filled precursor: Same as in Example 1.

[0056] (3) In-situ confined synthesis of basic copper nitrate: The above-mentioned precursor filled with copper ions was dispersed in distilled water (the ratio of precursor to distilled water was 1 g / 20 mL). Ammonia gas was introduced under stirring, and the ammonia gas introduction rate was controlled by a flow meter to be 80 mL / min and the introduction time was 20 min. Basic copper nitrate was generated by in-situ precipitation reaction at room temperature. After removing the supernatant, PS spheres filled with BCN were obtained. (4) Template removal: The PS template was removed by soaking and washing with acetone three times, and the crude product was obtained by centrifugation. The crude product was washed with deionized water and ethanol alternately until neutral, and then spray-dried to obtain porous basic copper nitrate.

[0057] Comparative Example 1 The only difference between this comparative example and Example 1 is that in step (2), the amount of polyvinylpyrrolidone (PVP, K30) added is 0; the rest of the steps are the same as in Example 1.

[0058] Comparative Example 2 The only difference between this comparative example and Example 1 is that in step (2), the vacuum condition is changed to immersion in an atmospheric environment; the rest of the steps are the same as in Example 1.

[0059] Comparative Example 3 The only difference between this comparative example and Example 1 is that in step (3), the alkali source is changed from ammonia to sodium hydroxide solution (30 mL of 2 mol / L sodium hydroxide solution), and the rest of the steps are the same as in Example 1.

[0060] Comparative Example 4 The only difference between this comparative example and Example 1 is that in step (1), during the preparation of the PS ball hard template, the final centrifugation condition is 9000 r / min for 10 min; the remaining steps are the same as in Example 1.

[0061] Performance testing The prepared basic copper nitrate was subjected to the following tests: (1) The microstructure and structure of the obtained basic copper nitrate samples were characterized by scanning electron microscopy and transmission electron microscopy. (2) The phase composition of the sample was analyzed by X-ray powder diffraction; (3) The particle size distribution of the sample was determined by a laser particle size analyzer; (4) The specific surface area of ​​the sample was determined by nitrogen adsorption method; (5) The flowability of the sample was determined by coating experiment; (6) Combustion performance test: 50% guanidine nitrate, 43% basic copper nitrate prepared in each example and comparative example, and 7% catalyst (aluminum powder) were mixed and granulated by mass percentage, loaded into a closed combustion chamber, and subjected to a high-temperature combustion test to measure the rate of change of pressure over time.

[0062] The performance test results are shown in Table 1 below.

[0063] Table 1

[0064] Table 1 shows that the porous basic copper nitrate prepared in the embodiments of the present invention, as detected by elemental analysis, conforms to the chemical structural formula Cu(NO3)2·3Cu(OH)2 and has a large specific surface area and uniform particle size. Compared with the comparative example, the porous basic copper nitrate prepared by the method of the present invention has a faster pressurization rate, better combustion performance, and a significantly improved specific surface area. At the same time, it avoids the problem of nanoparticle agglomeration, has better flowability, and can better meet the performance requirements of automotive airbag gas generators.

[0065] The basic copper nitrate prepared in Comparative Example 1 had a smaller specific surface area than the sample in Example 1; in terms of particle size distribution, the D50 was 4.10 mm, which still meets the requirements for basic copper nitrate used in airbags; however, the D90 was as high as 116.78 mm. Correspondingly, the peak pressure and pressure rise rate were also lower than those in Example 1. The above results indicate that without PVP, the PS spheres have a weak affinity for copper ions, making it difficult for copper ions to fully fill the pores of the spheres. This results in the inability of copper salt and sodium hydroxide to form heterogeneous nucleation on the template, leading to irregular particle size, severe agglomeration, and a larger specific surface area in the final product, further resulting in a decrease in gas production performance.

[0066] The basic copper nitrate prepared in Comparative Example 2 had a smaller specific surface area than the sample in Example 1; in terms of particle size distribution, D50 and D90 were 6.72 and 258.15 mm, respectively; the peak pressure and pressure rise rate were also lower than those in Example 1. These results indicate that, under atmospheric conditions without vacuum impregnation, the air adsorbed between the PS microspheres and on their surface hinders the penetration of copper ions, leading to reduced filling efficiency and uneven adsorption of copper ions in the template. This further results in uneven particle size distribution, a larger specific surface area, and decreased gas production performance in the sample.

[0067] The specific surface area of ​​the basic copper nitrate prepared in Comparative Example 3 was significantly smaller than that of the sample in Example 1; in the particle size distribution, the D90 was as high as 399.15 mm, indicating the presence of many coarse particles or agglomerates in the sample. Correspondingly, the peak pressure was 2.05 MPa, and the pressure rise rate was 72.3 MPa / ms, which was significantly lower than that in Example 1. The above results indicate that changing the alkali source from the less alkaline ammonia gas to the more alkaline sodium hydroxide resulted in excessively high local alkali concentrations in the system, and the NH3-NH4 group could not be constructed. + The buffer solution system leads to an imbalance in pH, which ultimately results in a wide particle size distribution, irregular morphology, and decreased combustion performance of the product.

[0068] In Comparative Example 4, the centrifugation rate was too high, which failed to construct uniformly densely packed PS spheres. The PS spheres were in a dispersed state, resulting in uneven distribution of the pores in the prepared basic copper nitrate, a lower specific surface area than in Example 1, a decreased pressurization rate, and poorer combustion performance.

[0069] Figure 1 The XRD pattern of the basic copper nitrate synthesized in Example 1 of this invention is shown. The XRD test results show that the diffraction peaks of the sample are consistent with the standard pattern PDF74-1749 published by the International Center for Diffraction Data (ICDD). Each characteristic peak is sharp and clear, indicating that the product is well crystallized. No characteristic peaks of other impurities such as CuO were observed, proving that the basic copper nitrate product has good purity.

[0070] Figure 2 This is a transmission electron microscope (TEM) image of the basic copper nitrate synthesized in Example 1 of this invention. The TEM image reveals a distinct alternating bright and dark structure in the porous BCN. This experimental result demonstrates that, on the one hand, repeated washing with DMF can completely remove the PS spheres acting as a hard template; on the other hand, it indicates that the PS spheres act as site occupants during BCN formation, and the product BCN completely replicates the internal pore structure of the PS template, ultimately forming a porous structure. Importantly, this porous structure provides numerous active sites for the subsequent filling and contact of the main combustion agent guanidine nitrate, as well as the adsorption and conversion of gaseous intermediates, significantly improving its combustion catalytic performance.

[0071] Figure 3The particle size distribution test diagram is shown for the basic copper nitrate synthesized in Example 1 of this invention. The particle size test results are D50 and D90, which are 2.10 mm and 4.90 mm, respectively, indicating that the BCN particles prepared by the method provided by this invention have fine particle size and concentrated particle size distribution.

[0072] Figure 4 The image shows the burst test curve of basic copper nitrate synthesized in Example 1 of this invention. The test results show that, compared with commercially available BCN and porous BCN, the thermal decomposition process of guanidine nitrate is significantly accelerated by the porous structure. Specifically, the porous BCN exhibits a faster pressure rise rate (92.1 MPa / ms), a higher peak pressure (approximately 3.30 MPa), and its pressure remains higher than that of commercially available BCN throughout the entire time range, demonstrating superior combustion performance and better meeting the requirements for airbag gas-generating materials.

[0073] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for preparing porous basic copper nitrate, characterized in that, Includes the following steps: S1. Monodisperse polystyrene microspheres were prepared by emulsion synthesis using styrene as a monomer, and polystyrene microspheres with a uniform and tightly packed structure were obtained by continuous slow centrifugation. S2. The polystyrene microspheres with the uniform and densely packed structure are added to a copper nitrate solution containing a dispersant, and vacuum treatment is carried out at room temperature. After centrifugation, a precursor filled with copper ions is obtained. S3. Disperse the copper ion-filled precursor in water, introduce ammonia gas under stirring conditions to carry out in-situ precipitation reaction, and obtain polystyrene microspheres filled with basic copper nitrate after filtration. S4. The polystyrene microspheres filled with basic copper nitrate are washed with an organic solvent to remove the hard template of the polystyrene microspheres, and then dried to obtain porous basic copper nitrate.

2. The method for preparing porous basic copper nitrate according to claim 1, characterized in that, In step S1, the rotation speed of the slow centrifugation is 2000~4000 r / min; the slow centrifugation time is 10~14 h.

3. The method for preparing porous basic copper nitrate according to claim 2, characterized in that, Step S1 specifically involves dispersing styrene in water, purging with nitrogen to remove air, adding an initiator at 60-75°C, and polymerizing for 12-24 hours. After this process, the mixture is slowly centrifuged at 2000-4000 r / min for 10-14 hours and then vacuum dried to obtain polystyrene microspheres with a uniform and tightly packed structure.

4. The method for preparing porous basic copper nitrate according to claim 1, characterized in that, In step S2, the mass ratio of the uniformly and tightly packed polystyrene microspheres to copper nitrate is (1~3):

1.

5. The method for preparing porous basic copper nitrate according to claim 1, characterized in that, In step S2, the solvent for the copper nitrate solution is ethanol and / or water; The concentration of copper nitrate in the copper nitrate solution is 20~100g / L; the concentration of dispersant in the copper nitrate solution is 10~50g / L.

6. The method for preparing porous basic copper nitrate according to claim 1, characterized in that, In step S2, the dispersant includes at least one of polyvinylpyrrolidone, polyvinyl alcohol, and polyethylene glycol.

7. The method for preparing porous basic copper nitrate according to claim 1, characterized in that, In step S3, the rate of ammonia gas introduction is 60~150 mL / min; the amount of ammonia gas introduced is 1.5~2.5 times the molar amount of copper nitrate in the copper nitrate solution. And / or, the temperature of the in-situ precipitation reaction is 20~45℃, and the time of the in-situ precipitation reaction is 3~8h.

8. The method for preparing porous basic copper nitrate according to claim 1, characterized in that, In step S4, the organic solvent includes at least one of N,N-dimethylformamide, tetrahydrofuran, dichloromethane, and acetone.

9. A porous basic copper nitrate, characterized in that, It is prepared by the method for preparing porous basic copper nitrate according to any one of claims 1 to 8.

10. A gas generating agent, characterized in that, The raw materials for preparation include guanidine nitrate, the porous basic copper nitrate as described in claim 9, and a catalyst.

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