A copper complex, a preparation method thereof and an application thereof

Abstract

The present invention discloses a copper complex, a preparation method thereof and an application thereof. Using 2,4-dihydroxybenzoic acid, a divalent copper salt and phenanthroline as raw materials, in a mixed solution of water and ethanol, after adjusting the pH value with a potassium hydroxide or sodium hydroxide solution, heating and stirring for reaction, filtering, washing and drying to obtain the copper complex. The synthesis method is simple and efficient, and is easy to industrialize. The copper complex of the present invention can be used as a thermal decomposition catalyst for energetic materials AP and RDX and applied to the catalyst manufacturing technology of propellants or the field of preparation of energetic materials, and its catalytic performance is significantly better than that of the traditional copper salt of 2,4-dihydroxybenzoic acid.

Description

Technical Field

[0001] The present invention belongs to the field of manufacturing technology of combustion catalysts for solid propellants or the field of preparation of energetic materials, and particularly relates to a copper complex, a preparation method thereof, and an application thereof. Background Art

[0002] As the main power source of solid rocket motors for missiles and rockets, solid propellants are an important research field in aerospace technology. At present, solid propellants are developing towards the directions of high energy, insensitive, low signature, and environmental protection. AP and RDX are the most common oxidizers in solid propellants, and their thermal decomposition properties play a key role in the combustion behavior of propellants: the lower the thermal decomposition temperature and apparent activation energy of the two, the shorter the ignition lag time and the higher the combustion rate of the propellant. Using a small amount of combustion catalyst can promote the thermal decomposition of the oxidizer, thereby improving the combustion performance of solid propellants.

[0003] Copper 2,4-dihydroxybenzoate (β-Cu) is a carboxylic acid complex formed by the reaction of divalent copper salts with 2,4-dihydroxybenzoic acid sodium salt (potassium salt), and is commonly used as a combustion catalyst for solid propellants, and has excellent performance in regulating the steady-state combustion of propellants, reducing the pressure index, and controlling energy release. However, the structural composition of β-Cu is unknown and its performance is not stable enough, which affects the application of the product. Summary of the Invention

[0004] To overcome the problems in the prior art, one of the purposes of the present invention is to provide a copper complex.

[0005] Another purpose of the present invention is to provide a preparation method of a copper complex.

[0006] Another purpose of the present invention is to provide an application of a copper complex.

[0007] To achieve the above purposes, the technical solutions adopted by the present invention are as follows:

[0008] A copper complex, the structural formula of the complex is shown as follows:

[0009]

[0010] A preparation method of a copper complex, putting 2,4-dihydroxybenzoic acid, divalent copper salt, and o-phenanthroline into a mixed solution of water and ethanol, adjusting the pH value to 6-8, and then reacting under heating, filtering, washing, and drying after the reaction to obtain the copper complex.

[0011] Preferably, the divalent copper salt is copper nitrate, copper chloride, or copper sulfate.

[0012] Preferably, the molar ratio of 2,4-dihydroxybenzoic acid, divalent copper salt, and o-phenanthroline is (1-2):1:(1-2).

[0013] Preferably, the volume ratio of water to ethanol in the water and ethanol mixed solution is 2:1 to 3:1.

[0014] Preferably, the pH value of the solution is adjusted to 6 - 8 with a KOH or NaOH solution.

[0015] Preferably, the reaction temperature is 50°C to 60°C and the time is 4 - 6 h.

[0016] Application of the copper complex as described above as a thermal decomposition catalyst for energetic materials AP and RDX.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] For the first time, the present invention obtains a single crystal structure of a ternary complex formed by divalent copper ions, 2,4 - dihydroxybenzoate anions, and phenanthroline. The crystal structure of this copper complex includes 1 divalent copper ion, 2 phenanthroline ligands, and 2 monovalent 2,4 - dihydroxybenzoate anions. The copper ion coordinates only with four nitrogen atoms of two phenanthrolines and the carboxyl oxygen atom of one 2,4 - dihydroxybenzoate anion to form a five - coordination structure, while the other 2,4 - dihydroxybenzoate anion does not participate in the coordination. The synthesis method of the present invention is simple, with high product yield and purity, and only one - step reaction, which is easy for industrial production.

[0019] Furthermore, when the volume ratio of water to ethanol is less than 3:1, the yield of the target product will decrease significantly.

[0020] Furthermore, when the reaction temperature is lower than 50°C or higher than 60°C, the corresponding yield will also decrease.

[0021] The copper complex described in the present invention can be used as a thermal decomposition catalyst for energetic materials AP and RDX and applied in the manufacturing technology of combustion catalysts for solid propellants or the field of energetic material preparation, and its catalytic performance is superior to that of traditional copper 2,4 - dihydroxybenzoate. Description of the Drawings

[0022] Figure 1 It is the single crystal structure of the copper complex in Example 1;

[0023] Figure 2 It is the powder XRD and single crystal simulated XRD patterns of the copper complex in Example 1;

[0024] Figure 3 It is the physical picture and SEM picture of the copper complex in Example 1; where (a) is the physical picture and (b) is the SEM picture;

[0025] Figure 4 It is the DSC curve of the copper complex in Example 1;

[0026] Figure 5 DSC curves of thermal decomposition of energetic materials AP and RDX in the presence of different catalysts for Example 2. Among them, (a) is the DSC curve of thermal decomposition of energetic material AP, and (b) is the DSC curve of thermal decomposition of energetic material RDX. Detailed implementation manners

[0027] The present invention will be described in detail below in conjunction with specific embodiments.

[0028] The structural formula of the copper complex of the present invention is shown in (Ⅰ):

[0029]

[0030] The preparation method of the copper complex is as follows:

[0031] 2,4-Dihydroxybenzoic acid, divalent copper salt and phenanthroline in a certain molar ratio are placed in a mixed solution of water and ethanol, and the pH value is adjusted to 6-8 with potassium hydroxide or sodium hydroxide solution, and then heated and stirred at 50-60 °C for 4-6 hours, filtered, washed and dried to obtain the copper complex.

[0032] Among them, the divalent copper salt includes copper nitrate, copper chloride and copper sulfate.

[0033] The reaction molar ratio of 2,4-dihydroxybenzoic acid, divalent copper salt and phenanthroline is 1-2:1:1-2.

[0034] The volume ratio of water and ethanol is 2:1-3:1.

[0035] Application of the copper complex as a thermal decomposition catalyst for energetic materials AP and RDX.

[0036] The present invention uses 2,4-dihydroxybenzoic acid, divalent copper salt and phenanthroline as raw materials to simply and efficiently synthesize a copper complex in one step. The yield of this complex is 82%, and its performance in catalyzing AP and RDX is better than that of traditional copper 2,4-dihydroxybenzoate. It can be used as a thermal decomposition catalyst for energetic materials AP (ammonium perchlorate) and RDX and applied to the manufacturing technology of combustion catalysts for solid propellants or the field of preparation of energetic materials.

[0037] The following are specific embodiments to further explain the technical solutions of the present invention.

[0038] Example 1

[0039] 0.31 g of 2,4-dihydroxybenzoic acid, 0.24 g of copper nitrate trihydrate, and 0.40 g of 1,10-phenanthroline monohydrate were placed in a mixed solution of 15 mL of deionized water and 5 mL of ethanol. The pH value was adjusted to 7 with potassium hydroxide solution, and then refluxed at 60 °C for 4 hours to obtain a green precipitate. After filtration, washing, and drying, 0.6 g of copper complex was obtained with a yield of 82.2%. C, H, and N were determined by an elemental analyzer as (the values in parentheses are the theoretical values): C: 62.53 (62.51), N: 7.64 (7.67). The content of Cu element determined by ICP-AES was (%) (the value in parentheses is the theoretical value): 8.9 (8.70). The filtrate was placed at room temperature, and green transparent crystals precipitated after one week.

[0040] Tested by X-ray diffraction, the crystal is monoclinic system, space group P21 / n, and the unit cell parameters Z = 4, μ = 0.764 mm -1 , F(000) = 1500.0, ρ c = 1.550 g·cm -3 , R1 = 0.0537 and wR2 = 0.1329.

[0041] Figure 1 is the single crystal structure of the copper complex; it can be seen from Figure 1 that there is 1 divalent copper ion, 2 1,10-phenanthroline ligands, and 2 monovalent anions of 2,4-dihydroxybenzoic acid in its crystal structure. The copper ion coordinates only with the four nitrogen atoms of two 1,10-phenanthrolines and the carboxyl oxygen atom of one 2,4-dihydroxybenzoic acid anion to form a five-coordination structure, while the other 2,4-dihydroxybenzoic acid anion does not participate in the coordination.

[0042] Figure 2 are the powder XRD and single crystal simulated XRD patterns of the copper complex. It can be seen from Figure 2 that the positions and numbers of the peaks on the powder XRD pattern of this substance are almost completely consistent with those on the single crystal simulated XRD pattern, indicating that the obtained powder and the tested single crystal are the same substance and the purity of the powder is relatively high.

[0043] Figure 3 In Figure 3 (a) and (b) are the physical picture and SEM picture of the copper complex; it can be seen from Figure 3 (a) and (b) that the microscopic morphology of the obtained copper complex is highly regular rod-shaped, and its size is about 1 μm.

[0044] Figure 4 is the DSC curve of the copper complex; it can be seen from Figure 4 that the copper complex has four endothermic peaks, and the first endothermic peak occurs at 215 - 219 °C, indicating that it has relatively high thermal stability.

[0045] Example 2

[0046] The copper complex synthesized by the method of Example 1 was uniformly mixed with AP and RDX at a mass ratio of 1:4, and DSC measurement was carried out under the condition of a heating rate of 10 °C, and the results are as Figure 5 shown below.

[0047] Figure 5 In (a), it is the DSC curve of the copper complex of the present invention and copper 2,4-dihydroxybenzoate respectively catalyzing the energetic material AP. The peak temperatures of the low-temperature decomposition and high-temperature decomposition stages of pure AP are 309.2 °C and 406.5 °C respectively, and the apparent heat release is 742.5 J g -1 , after adding the copper complex, its two independent exothermic processes are combined into one, and the peak temperature of the exothermic stage is 52.6 °C lower than that of the high-temperature decomposition stage of pure AP, and the heat release increases to 2115 J g -1 . For the copper 2,4-dihydroxybenzoate catalyzing AP, although the peak temperature is advanced more, multiple exothermic peaks appear, indicating that its catalytic stability is poor. Therefore, generally speaking, the copper complex of the present invention has a better effect on catalyzing AP.

[0048] Figure 5 In (b), it is the DSC curve of the copper complex and copper 2,4-dihydroxybenzoate respectively catalyzing the energetic material RDX. The peak temperature of the exothermic stage of pure RDX is 242.3 °C, and the apparent heat release is 797 J g -1 , after adding the copper complex, the peak temperature of its exothermic stage is advanced to 181.4 °C, and it occurs before the endothermic peak of pure RDX, and its apparent heat release increases to 1493 J g -1 , and the catalytic effect is significantly better than that of copper 2,4-dihydroxybenzoate. Therefore, the complex of the present invention has a better effect on catalyzing RDX.

[0049] Example 3

[0050] 0.31 g of 2,4-dihydroxybenzoic acid, 0.17 g of copper dichloride dihydrate, and 0.40 g of 1,10-phenanthroline monohydrate were placed in a mixed solution of 15 mL of deionized water and 7.5 mL of ethanol, and the pH value was adjusted to 6 with potassium hydroxide solution, and then refluxed at 60 °C for 4 hours to obtain a green precipitate, which was filtered, washed and dried to obtain 0.46 g of the target copper complex with a yield of 63.0%.

[0051] Example 4

[0052] Dissolve 0.31 g of 2,4-dihydroxybenzoic acid, 0.25 g of copper sulfate pentahydrate, and 0.40 g of 1,10-phenanthroline monohydrate in a mixed solution of 15 mL of deionized water and 7.5 mL of ethanol. Adjust the pH value to 7 with potassium hydroxide solution, then reflux at 52 °C for 4 hours to obtain a green precipitate. Filter, wash, and dry to obtain 0.42 g of the target copper complex with a yield of 57.5%.

[0053] Example 5

[0054] Dissolve 0.31 g of 2,4-dihydroxybenzoic acid, 0.48 g of copper nitrate trihydrate, and 0.40 g of 1,10-phenanthroline monohydrate in a mixed solution of 15 mL of deionized water and 6 mL of ethanol. Adjust the pH value to 7 with sodium hydroxide solution, then reflux at 55 °C for 4 hours to obtain a green precipitate. Filter, wash, and dry to obtain 0.48 g of the target copper complex with a yield of 65.7%.

[0055] Example 6

[0056] Dissolve 0.31 g of 2,4-dihydroxybenzoic acid, 0.48 g of copper nitrate trihydrate, and 0.40 g of 1,10-phenanthroline monohydrate in a mixed solution of 15 mL of deionized water and 6 mL of ethanol. Adjust the pH value to 8 with sodium hydroxide solution, then reflux at 60 °C for 4 hours to obtain a green precipitate. Filter, wash, and dry to obtain 0.50 g of the target copper complex with a yield of 68.5%.

[0057] Example 7

[0058] Dissolve 0.31 g of 2,4-dihydroxybenzoic acid, 0.24 g of copper nitrate trihydrate, and 0.40 g of 1,10-phenanthroline monohydrate in a mixed solution of 15 mL of deionized water and 7.5 mL of ethanol. Adjust the pH value to 7 with sodium hydroxide solution, then reflux at 65 °C for 4 hours to obtain a green precipitate. Filter, wash, and dry to obtain 0.43 g of the target copper complex with a yield of 58.9%.

[0059] Example 8

[0060] Dissolve 0.16 g of 2,4-dihydroxybenzoic acid, 0.24 g of copper nitrate trihydrate, and 0.20 g of 1,10-phenanthroline monohydrate in a mixed solution of 15 mL of deionized water and 5 mL of ethanol. Adjust the pH value to 7 with sodium hydroxide solution, then reflux at 65 °C for 5 hours to obtain a green precipitate. Filter, wash, and dry to obtain 0.22 g of the target copper complex with a yield of 60.3%.

[0061] Example 9

[0062] 0.16 g of 2,4-dihydroxybenzoic acid, 0.24 g of copper nitrate trihydrate, and 0.3 g of 1,10-phenanthroline monohydrate were placed in a mixed solution of 12.5 mL of deionized water and 5 mL of ethanol. The pH value was adjusted to 7 with sodium hydroxide solution, and then refluxed at 65 °C for 6 hours to obtain a green precipitate. After filtration, washing, and drying, 0.20 g of the target copper complex was obtained with a yield of 54.8%.

Claims

1. A copper complex, characterized in that, The structural formula of the complex is as follows: 。 2. A method for preparing a copper complex as described in claim 1, characterized in that, 2,4-dihydroxybenzoic acid, divalent copper salt and o-phenanthroline are placed in a mixed solution of water and ethanol. After adjusting the pH value to 6-8, the reaction is carried out under heating. After the reaction, filtration, washing and drying are carried out to obtain the copper complex.

3. The preparation method of the copper complex according to claim 2, characterized in that, The divalent copper salt is copper nitrate, copper chloride or copper sulfate.

4. The preparation method of the copper complex according to claim 2, characterized in that, The molar ratio of 2,4-dihydroxybenzoic acid, divalent copper salt and o-phenanthroline is (1-2):1:(1-2).

5. The preparation method of the copper complex according to claim 2, characterized in that, The volume ratio of water to ethanol in the mixed solution of water and ethanol is 2:1-3:

1.

6. The preparation method of the copper complex according to claim 2, characterized in that, The pH value of the solution is adjusted to 6-8 by using KOH or NaOH solution.

7. The preparation method of the copper complex according to claim 2, wherein, The reaction temperature is 50°C-60°C and the time is 4-6 h.

8. Application of the copper complex according to claim 1 as a thermal decomposition catalyst for energetic materials AP and RDX.

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