A bismuth complex, its preparation method and application

Abstract

The present invention discloses a bismuth complex, a preparation method thereof and an application thereof. A trivalent bismuth salt and mannitol are mixed and then 2,4-dihydroxybenzoic acid and 2,2'-bipyridine are added to a mixed solution of water and ethanol. After adjusting the pH value to 6-8, a reaction is carried out to obtain the bismuth complex. The crystal structure of the bismuth complex includes one trivalent bismuth ion, two 2,2'-bipyridine ligands and three monovalent anions of 2,4-dihydroxybenzoic acid. The bismuth ion coordinates only with two nitrogen atoms of one 2,2'-bipyridine and the carboxyl oxygen atoms of three 2,4-dihydroxybenzoic acid anions to form a six-coordination structure, while the other 2,2'-bipyridine molecule does not undergo a coordination effect but is connected to the adjacent 2,4-dihydroxybenzoic acid anion through a hydrogen bond, and the structure is more stable. The synthesis method of the present invention is simple, the product has a high yield and high purity, and only one-step reaction is involved, which is easy for industrial production.

Description

Technical Field

[0001] The present invention belongs to the manufacturing technology of combustion catalysts for solid propellants, and particularly relates to a bismuth 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. Ammonium perchlorate (AP) and cyclotrimethylenetrinitramine (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 of the propellant and the higher the combustion rate. Using a small amount of combustion catalyst can promote the thermal decomposition of the oxidizer, thereby improving the combustion performance of solid propellants.

[0003] Lead compounds are very important burning rate catalysts. The addition of them can effectively increase the burning rate of propellants and reduce the pressure index, but they are highly toxic and extremely harmful to the human body. In addition, lead compounds are also a source of smoke. Combustion decomposition will produce lead oxide, generating white or blue (cyan) smoke, which is not conducive to missile guidance [Reference 1]. While bismuth organic salts, as green catalysts, can replace highly toxic lead compounds to obtain solid propellants that are beneficial to environmental protection [Reference 2]. At the same time, after bismuth 2,4-dihydroxybenzoate replaces lead compounds, the cyan smoke generated by the combustion of lead catalysts is eliminated, reducing the signature of the propellant, which is beneficial to the stealth and guidance of missiles [Reference 3].

[0004] Bismuth ions are extremely strong Lewis acids and can relatively easily expand their coordination range to form high-valence coordination complexes, which will result in many bismuth coordination complexes often being coordination polymers or oligomers [Reference 4], and single crystal structures are not easily obtained. Many researchers have tried to obtain the crystal structure of β-Bi, but there has been no report so far, so there have been many structural speculations, which is not conducive to its application.

[0005] [1] Song Xiuduo, Zhao Fengqi, Chen Pei. Latest research progress on non-lead burning rate catalysts for solid propellants [J]. Chinese Journal of Energetic Materials, 2004, 12(3): 184-188;

[0006] [2] Zhao Fengqi, Li Shangwen, Cai Bingyuan. Ecologically safe bismuth-containing catalysts for double-base propellants [J]. Chinese Journal of Explosives & Propellants, 1998, (1): 54-56;

[0007] [3] Song Xiuduo, Zhao Fengqi, Xu Siyu, Gao Hongxu, Gao Yin. Catalytic effect of bismuth 2,4-dihydroxybenzoate on the combustion of double-base propellants[J]. Chinese Journal of Explosives & Propellants, 2006(01): 36-39;

[0008] [4] T. Ould-Ely, J. H. Thurston, K. H. Whitmire. Heterobimetallic bismuth-transition metal coordination complexes as single-source molecular precursors for the formation of advanced oxide materials[J]. Comptes Rendus Chimie, 2005, Vol.8 (11): 1906-1921. SUMMARY OF THE INVENTION

[0009] To solve the problems in the prior art that single crystal structures cannot be obtained and the performance is unstable, the object of the present invention is to provide a bismuth complex and its preparation method and application.

[0010] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0011] A bismuth complex, the structural formula of the bismuth complex is as follows:

[0012] .

[0013] A preparation method of a bismuth complex, mixing a trivalent bismuth salt and mannitol, and then adding 2,4-dihydroxybenzoic acid and 2,2'-bipyridine into a mixed solution of water and ethanol, adjusting the pH value to 6-8 and then reacting to obtain the bismuth complex.

[0014] Further, the trivalent bismuth salt is bismuth chloride, bismuth nitrate or bismuth acetate.

[0015] Further, the molar ratio of 2,4-dihydroxybenzoic acid, trivalent bismuth salt, mannitol and 2,2'-bipyridine is (1-2):1:(1-1.5):(1-2).

[0016] Further, the volume ratio of water to ethanol in the mixed solution of water and ethanol is 2:1-3:1.

[0017] Further, the pH value is adjusted to 6-8 by using a KOH or NaOH solution.

[0018] Further, the reaction temperature is 50°C-65°C and the time is 3-6h.

[0019] Application of the bismuth complex as described above as a thermal decomposition catalyst for energetic materials AP and RDX

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] For the first time, the present invention obtains a single crystal structure of a ternary bismuth complex formed by trivalent bismuth ions, 2,4-dihydroxybenzoate anions, and 2,2'-bipyridine. The crystal structure of the bismuth complex includes 1 trivalent bismuth ion, 2 2,2'-bipyridine ligands, and 3 monovalent 2,4-dihydroxybenzoate anions. The bismuth ion coordinates only with two nitrogen atoms of one 2,2'-bipyridine and carboxyl oxygen atoms of three 2,4-dihydroxybenzoate anions to form a six-coordinate structure, while the other 2,2'-bipyridine molecule does not undergo coordination, but is connected to the adjacent dihydroxybenzoate anion through hydrogen bonds. The synthesis method of the present invention is simple, the product has a high yield and high purity, and it is only one-step reaction, which is easy for industrial production.

[0022] Since bismuth salts are insoluble in water, after adding mannitol and mixing, they can be dissolved in water to obtain Bi 3+ , which is easy to coordinate with polydentate ligands containing oxygen and nitrogen atoms. Subsequently, according to the hard and soft acid-base theory, the 2,4-dihydroxybenzoic acid molecule contains a carboxyl group belonging to a hard base, and Bi 3+ is close to a soft acid, and the coordination bond between the oxygen atom in the carboxyl group and metallic bismuth is more stable, and the performance is more stable. 2,2'-Bipyridine is an N'N-bidentate chelating ligand and can form complexes with many metal ions.

[0023] Furthermore, when the volume ratio of water to ethanol is less than 3:1, the yield of the target product will decrease significantly.

[0024] Furthermore, when the reaction temperature is lower than 50 °C or higher than 60 °C, the corresponding yield will also decrease.

[0025] Furthermore, when the molar ratio of trivalent bismuth salt to mannitol is less than 1:1.5, the yield of the target product will decrease significantly. Description of the Drawings

[0026] Figure 1 is the single crystal structure of the bismuth complex in Example 1;

[0027] Figure 2 is the powder XRD and single crystal simulated XRD patterns of the bismuth complex in Example 1;

[0028] Figure 3 is the SEM images of the single crystal and powder of the bismuth complex in Example 1; among them, (a) is the single crystal of the bismuth complex, and (b) is the powder of the bismuth complex;

[0029] Figure 4Infrared spectrum of the bismuth complex of Example 1;

[0030] Figure 5 DSC curve of the bismuth complex of Example 1;

[0031] Figure 6 DSC curves of the catalytic thermal decomposition of energetic materials AP and RDX in Example 1. Among them, (a) is the DSC curve of the thermal decomposition of energetic material AP, and (b) is the DSC curve of the thermal decomposition of energetic material RDX. Detailed implementation mode

[0032] The present invention will be described in detail below in conjunction with specific embodiments.

[0033] The structural formula of the bismuth complex of the present invention is shown in (I):

[0034]

[0035] (I)

[0036] The preparation method of the bismuth complex is as follows:

[0037] After the trivalent bismuth salt and mannitol are mixed and ground, they are placed in a mixed solution of water and ethanol together with 2,4-dihydroxybenzoic acid and 2,2'-bipyridine. 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 3-6 hours, and the bismuth complex is obtained by filtration, washing and drying.

[0038] Among them, the trivalent bismuth salt is bismuth acetate, bismuth nitrate or bismuth chloride.

[0039] The reaction molar ratio of 2,4-dihydroxybenzoic acid, trivalent bismuth salt, mannitol and 2,2'-bipyridine is (1-2):1:(1-1.5):(1-2).

[0040] The volume ratio of water to ethanol is 2:1-3:1.

[0041] The present invention uses 2,4-dihydroxybenzoic acid, trivalent bismuth salt, mannitol and 2,2'-bipyridine as raw materials to simply and efficiently synthesize a bismuth complex in one step. The yield of this complex is 78.3%, and it can be used as a thermal decomposition catalyst for energetic materials AP and RDX and applied to the manufacturing technology of combustion catalysts for solid propellants or the field of preparation of energetic materials.

[0042] The following are specific examples to further explain the technical solutions of the present invention.

[0043] Example 1

[0044] 0.49 g of bismuth nitrate pentahydrate was mixed with 0.18 g of mannitol and ground to a viscous state. Subsequently, it was placed in a mixed solution of 15 mL of deionized water and 5 mL of ethanol. Then, 0.31 g of 2,4-dihydroxybenzoic acid and 0.31 g of 2,2'-bipyridine were added. The pH value was adjusted to 7 with potassium hydroxide solution, and then refluxed at 60 °C for 3 hours to obtain a white precipitate. After filtration, washing, and drying, 0.768 g of bismuth complex was obtained with a yield of 78.3%.

[0045] IR (KBr) (cm -1 ):3115 (s), 3066 (s), 2980 (s), 2358 (m), 2009(s), 1978(s), 1869(s), 1791(s), 1627(w), 1595(w), 1558(m), 1539(m), 1506(m), 1456(s),1382(m), 1325(s), 1278(s), 1151(w), 1101(m), 1018(m), 1001(m), 975(m), 839(m), 761(w), 729(m), 696(m), 630(w), 534(m). C, H, N were determined by an elemental analyzer as (the values in parentheses are theoretical values) C: 50.19 (50.17), N: 5.68 (5.71). The content of Bi element determined by ICP-AES was (%) (the values in parentheses are theoretical values): 21.28 (21.31). The filtrate was placed at room temperature, and colorless transparent crystals precipitated after 3 days.

[0046] Tested by X-ray diffraction, the crystal was triclinic system, space group P-1 , the unit cell parameters were a = 10.0602(8) Å, b = 11.6419(8) Å, c = 17.5246(11) Å, V = 1807.6(2) Å 3 , Z = 2, μ = 4.952 mm -1 , F(000) = 968.0, ρ c = 1.802 g·cm -3 , R 1 = 0.0475 and wR 2 = 0.0999.

[0047] Figure 1 was the single crystal structure of the bismuth complex; from Figure 1It can be seen that its crystal structure includes one trivalent bismuth ion, two 2,2'-bipyridine ligands, and three monovalent 2,4-dihydroxybenzoate anions. The bismuth ion coordinates only with the two nitrogen atoms of one 2,2'-bipyridine and the carboxyl oxygen atoms of three 2,4-dihydroxybenzoate anions to form a six-coordination structure, while the other 2,2'-bipyridine ligand does not participate in coordination and is connected to the nearby 2,4-dihydroxybenzoate anion through hydrogen bonding.

[0048] Figure 2 Powder XRD and single-crystal simulated XRD patterns of the bismuth complex. From Figure 2 It can be seen that the positions and numbers of the peaks in the powder XRD pattern and the single-crystal simulated XRD pattern of this substance almost completely coincide, indicating that the obtained powder and the tested single crystal are the same substance and the powder has a high purity.

[0049] Figure 3 In (a) and (b) are SEM images of the single crystal and powder of the bismuth complex; from Figure 3 In (a) and (b), it can be seen that the microscopic morphology of the obtained single crystal of the bismuth complex is flaky, and its size is approximately 2 - 3 μm.

[0050] Figure 4 is the infrared spectrum of the bismuth complex. Among them, the characteristic peak of the antisymmetric stretching vibration of -OBi in -COOBi is at 1325 cm -1 The antisymmetric stretching vibration peak of C=O of -COOH is at 1629 cm -1 and the characteristic peak of CO -1 is at 2360 cm 2 .

[0051] Figure 5 is the DSC curve of the bismuth complex; from Figure 5 it can be seen that the bismuth complex has two endothermic peaks, and the first endothermic peak occurs at 202 °C, indicating its high thermal stability.

[0052] Thermal decomposition performance test:

[0053] The bismuth 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 a heating rate of 10 °C, and the results shown in Figure 6 were obtained.

[0054] Figure 6 In (a) is the DSC curve of the bismuth complex of the present invention 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 bismuth complex, the peak temperatures of its two exothermic decomposition peaks are advanced by 27.3 °C and 91.7 °C respectively, and the main decomposition process is concentrated around 280 °C, and the heat release increases to 1451 J g -1 .

[0055] Figure 6 In (b) is the DSC curve of the bismuth complex 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 bismuth complex, the peak temperature of its exothermic decomposition is slightly advanced.

[0056] It can be seen that the bismuth complex of the present invention can be used as a combustion catalyst for energetic materials AP and RDX.

[0057] Example 2

[0058] 0.27 g of bismuth acetate and 0.18 g of mannitol were mixed and ground to a viscous state, then placed in a mixed solution of 15 mL of deionized water and 7.5 mL of ethanol, then 0.31 g of 2,4-dihydroxybenzoic acid and 0.31 g of 2,2'-bipyridine were added, and the pH value was adjusted to 6 with potassium hydroxide solution, and then refluxed at 60 °C for 3 hours to obtain a white precipitate, which was filtered, washed and dried to obtain 0.67 g of the target bismuth complex, and the yield was 68.3%.

[0059] IR (KBr) (cm -1 ): 3153 (s), 3080 (s), 3007 (s), 2711 (s), 1978(s), 1716(s), 1683(s), 1629(w), 1595(m), 1539(m), 1508(m), 1456(s), 1440(m), 1382(m),1323(s), 1174(w), 1099(m), 1001(m), 840(m), 775(w), 632(w), 541(m). C, H, N were determined by an elemental analyzer as (the values in parentheses are theoretical values) C: 50.21 (50.17), N: 5.66 (5.71). The Bi element content determined by ICP-AES is (%) (the values in parentheses are theoretical values): 21.26 (21.31).

[0060] Example 3

[0061] Mix 0.27 g of bismuth acetate with 0.27 g of mannitol and grind them to a viscous state. Then place them in a mixed solution of 15 mL of deionized water and 7.5 mL of ethanol. Then add 0.31 g of 2,4-dihydroxybenzoic acid and 0.31 g of 2,2'-bipyridine. Adjust the pH value to 7 with potassium hydroxide solution. Then reflux at 55 °C for 4 hours to obtain a white precipitate. Filter, wash, and dry to obtain 0.595 g of the target bismuth complex with a yield of 60.7%.

[0062] Example 4

[0063] Mix 0.31 g of bismuth chloride with 0.18 g of mannitol and grind them to a viscous state. Then place them in a mixed solution of 15 mL of deionized water and 6 mL of ethanol. Then add 0.31 g of 2,4-dihydroxybenzoic acid and 0.31 g of 2,2'-bipyridine. Adjust the pH value to 7 with potassium hydroxide solution. Then reflux at 50 °C for 6 hours to obtain a white precipitate. Filter, wash, and dry to obtain 0.574 g of the target bismuth complex with a yield of 58.6%

[0064] Example 5

[0065] Mix 0.31 g of bismuth chloride with 0.27 g of mannitol and grind them to a viscous state. Then place them in a mixed solution of 15 mL of deionized water and 6 mL of ethanol. Then add 0.31 g of 2,4-dihydroxybenzoic acid and 0.31 g of 2,2'-bipyridine. Adjust the pH value to 8 with potassium hydroxide solution. Then reflux at 60 °C for 3 hours to obtain a white precipitate. Filter, wash, and dry to obtain 0.513 g of the target bismuth complex with a yield of 52.3%

[0066] Example 6

[0067] Mix 0.49 g of bismuth nitrate pentahydrate with 0.18 g of mannitol and grind them to a viscous state. Then place them in a mixed solution of 15 mL of deionized water and 7.5 mL of ethanol. Then add 0.31 g of 2,4-dihydroxybenzoic acid and 0.31 g of 2,2'-bipyridine. Adjust the pH value to 7 with potassium hydroxide solution. Then reflux at 65 °C for 3 hours to obtain a white precipitate. Filter, wash, and dry to obtain 0.6 g of the target bismuth complex with a yield of 61.3%

[0068] Example 7

[0069] 0.49 g of bismuth nitrate pentahydrate was mixed with 0.18 g of mannitol and ground to a viscous state. Subsequently, it was placed in a mixed solution of 15 mL of deionized water and 5 mL of ethanol. Then, 0.16 g of 2,4-dihydroxybenzoic acid and 0.156 g of 2,2'-bipyridine were added. The pH value was adjusted to 7 with potassium hydroxide solution, and then refluxed at 65 °C for 3 hours to obtain a white precipitate. After filtration, washing, and drying, 0.541 g of the target bismuth complex was obtained, with a yield of 55.2%.

[0070] Example 8

[0071] 0.49 g of bismuth nitrate pentahydrate was mixed with 0.18 g of mannitol and ground to a viscous state. Subsequently, it was placed in a mixed solution of 15 mL of deionized water and 7.5 mL of ethanol. Then, 0.16 g of 2,4-dihydroxybenzoic acid and 0.156 g of 2,2'-bipyridine were added. The pH value was adjusted to 7 with potassium hydroxide solution, and then refluxed at 60 °C for 3 hours to obtain a white precipitate. After filtration, washing, and drying, 0.575 g of the target bismuth complex was obtained, with a yield of 58.6%.

[0072] Example 9

[0073] 0.49 g of bismuth nitrate pentahydrate was mixed with mannitol and ground to a viscous state. Subsequently, it was placed in a mixed solution of 15 mL of deionized water and 5 mL of ethanol. Then, 2,4-dihydroxybenzoic acid and 2,2'-bipyridine were added. The pH value was adjusted to 7 with potassium hydroxide solution, and then refluxed at 60 °C for 3 hours to obtain a white precipitate. After filtration, washing, and drying, a bismuth complex was obtained. Among them, the molar ratio of 2,4-dihydroxybenzoic acid, bismuth nitrate pentahydrate, mannitol, and 2,2'-bipyridine was 1:1:1:1.

[0074] Example 10

[0075] 0.49 g of bismuth nitrate pentahydrate was mixed with mannitol and ground to a viscous state. Subsequently, it was placed in a mixed solution of 15 mL of deionized water and 6 mL of ethanol. Then, 2,4-dihydroxybenzoic acid and 2,2'-bipyridine were added. The pH value was adjusted to 7 with potassium hydroxide solution, and then refluxed at 52 °C for 5 hours to obtain a white precipitate. After filtration, washing, and drying, a bismuth complex was obtained. Among them, the molar ratio of 2,4-dihydroxybenzoic acid, bismuth nitrate pentahydrate, mannitol, and 2,2'-bipyridine was 2:1:1.5:2.

[0076] Example 11

[0077] Mix 0.49 g of bismuth nitrate pentahydrate with mannitol and grind them until they become viscous. Then place them in a mixed solution of 15 mL of deionized water and 7 mL of ethanol. Next, add 2,4-dihydroxybenzoic acid and 2,2'-bipyridine, and adjust the pH value to 7 with potassium hydroxide solution. Then reflux at 57 °C for 4 hours to obtain a white precipitate. Filter, wash, and dry it to obtain a bismuth complex. Among them, the molar ratio of 2,4-dihydroxybenzoic acid, bismuth nitrate pentahydrate, mannitol, and 2,2'-bipyridine is 1.5:1:1.2:1.5.

Claims

1. A bismuth complex, characterized in that the structural formula of the bismuth complex is as follows: 。 2. The preparation method of the bismuth complex according to claim 1, characterized in that a trivalent bismuth salt and mannitol are mixed and then 2,4-dihydroxybenzoic acid and 2,2'-bipyridine are added to a mixed solution of water and ethanol, the pH value is adjusted to 6-8 and then reacted to obtain the bismuth complex.

3. The preparation method of the bismuth complex according to claim 2, characterized in that the trivalent bismuth salt is bismuth chloride, bismuth nitrate or bismuth acetate.

4. The preparation method of the bismuth complex according to claim 2, characterized in that the molar ratio of 2,4-dihydroxybenzoic acid, trivalent bismuth salt, mannitol and 2,2'-bipyridine is (1-2):1:(1-1.5):(1-2).

5. The preparation method of the bismuth 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 bismuth complex according to claim 2, characterized in that a KOH or NaOH solution is used to adjust the pH value to 6-8.

7. The preparation method of the bismuth complex according to claim 2, characterized in that the reaction temperature is 50°C-65°C and the time is 3-6 h.

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

Images