A method to improve the hydrophobicity of α-aluminum trihydride

Abstract

This invention discloses a method for improving the hydrophobicity of α-aluminum trihydrogenate: First, a surface modifier is dispersed in a first inert solvent to obtain an inert dispersion. Then, α-aluminum trihydrogenate is added to the inert dispersion, followed by ultrasonic dispersion, stirring, filtration to remove the solvent, and drying to obtain treated α-aluminum trihydrogenate. Next, an organic film-forming agent is dissolved in a second inert solvent, and the treated α-aluminum trihydrogenate is added. After stirring, a curing agent is added, stirring again, filtration to remove the solvent, and drying, hydrophobic α-aluminum trihydrogenate is obtained. This method significantly improves the hydrophobicity of α-aluminum trihydrogenate products, increasing the static water contact angle from approximately 50° to 90–120°. Storage and usage stability are also correspondingly improved. After 7 days of storage at 30°C and 75% relative humidity, the product weight gain is between 0.1% and 0.9%. This method is simple to operate, operates under mild conditions, and has good safety during the process.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage and energetic materials technology, specifically relating to a method for improving the hydrophobicity of α-aluminum trihydride. Background Technology

[0002] Alpha-aluminum trihydride has a high hydrogen content and low toxicity, with a theoretical hydrogen content of 10.08% and a hydrogen storage density of 148 g / L, twice that of liquid hydrogen (70.8 g / L). Hydrogen has a very high calorific value, and its combustion product is water. Currently, aluminum trihydride has seven different crystal forms: α, α′, β, γ, δ, ε, and ζ. Alpha-aluminum trihydride is the most stable crystal form and can be considered an ideal hydrogen storage material.

[0003] Because α-aluminum trihydride is a metastable compound, it is highly sensitive to contact with water or moisture during storage or use, which may accelerate its decomposition, thereby reducing its stability and safety during storage and use, and affecting its application in solid propellants or as a hydrogen storage material. Therefore, finding effective methods to improve the hydrophobicity of α-aluminum trihydride is an urgent problem to be solved.

[0004] In the methods for improving the thermal stability of α-aluminum trihydride disclosed in CN112279742A, CN111892468B, CN112266313B, and CN112125768B, ethylene-vinyl alcohol copolymer and C are used respectively. 60 α-Aluminum trihydrogenide is coated with polyvinylidene fluoride and polycarbonate. Summary of the Invention

[0005] The purpose of this invention is to solve the problem of accelerated decomposition of α-aluminum trihydride due to moisture or humidity during storage or use. It provides a method to improve the hydrophobicity of α-aluminum trihydride. After treatment by this method, the hydrophobicity of α-aluminum trihydride is significantly improved, eliminating the adverse factors in the storage or use of α-aluminum trihydride and increasing the stability, convenience and safety of α-aluminum trihydride storage or use.

[0006] The method of the present invention proceeds through the following technical steps: dispersing a surface modifier in a first inert solvent, then adding α-aluminum trihydrogenate to the dispersion solvent, ultrasonically dispersing, stirring, filtering to remove the solvent, adding the treated α-aluminum trihydrogenate and an organic film-forming agent to a second inert solvent, stirring, adding a curing agent, stirring, removing the second inert solvent, drying the treated α-aluminum trihydrogenate, and sieving to obtain α-aluminum trihydrogenate with good hydrophobicity.

[0007] The technical solution of this invention is to provide a method for improving the hydrophobicity of α-aluminum trihydrogenide. First, a surface modifier is dispersed in a first inert solvent to obtain an inert dispersion. Then, α-aluminum trihydrogenide is added to the inert dispersion, followed by ultrasonic dispersion, stirring, filtration to remove the solvent, and drying to obtain treated α-aluminum trihydrogenide. Then, an organic film-forming agent is dissolved in a second inert solvent, and the above-treated α-aluminum trihydrogenide is added. After stirring, adding a curing agent, stirring again, filtration to remove the solvent, and drying, hydrophobic α-aluminum trihydrogenide is obtained.

[0008] Furthermore, the aforementioned surface modifier is a particulate material containing carbon elements, with a particle size D. 50 The thickness is no more than 5 μm; the amount of the surface modifier added is 0.05 to 3% of the mass of α-aluminum trihydride; the mass ratio of the surface modifier to the first inert solvent is 1:(10 to 100).

[0009] Furthermore, the aforementioned organic film-forming agent is bisphenol A type diglycidyl ether, and the mass ratio of the organic film-forming agent to the second inert solvent is 1:(10-100); the curing agent is a polyamide amine curing agent with an amine value ranging from 200 to 350 mg KOH / g, and the amount of curing agent added is 0.5-5% of the mass of α-aluminum trihydride.

[0010] Furthermore, the solvent removal and drying processes described above are carried out at temperatures ranging from 30 to 70°C, and for periods ranging from 2 to 48 hours.

[0011] Furthermore, the particle size D of the aforementioned α-aluminum trihydride 50 It is distributed in the range of 5–350 μm.

[0012] Furthermore, the above-mentioned surface modifier is added at 0.1% of the mass of α-aluminum trihydride; the mass ratio of the surface modifier to the first inert solvent is 1:50; the mass ratio of the organic film-forming agent to the second inert solvent is 1:70; the curing agent has an amine value range of 220-320 mgKOH / g, and its addition amount is 1% of the mass of α-aluminum trihydride; the temperature for solvent removal by filtration and drying is 40℃; the time is 24 hours; the particle size D of α-aluminum trihydride is... 50 It is distributed in the range of 15–30 μm.

[0013] Furthermore, the aforementioned carbon-containing particulate matter includes one or more of carbon black, graphene, and carbon nanotubes.

[0014] Furthermore, the first and second inert solvents mentioned above both refer to alkanes that are inert when mixed with α-aluminum trihydride and whose boiling point at normal pressure does not exceed 100°C.

[0015] Furthermore, both the first and second inert solvents are selected from one or more of pentane, n-hexane, cyclohexane, and petroleum ether 60-90. Preferably, petroleum ether 60-90 refers to petroleum ether whose initial boiling point is not lower than 60 degrees Celsius and whose final boiling point is not higher than 90 degrees Celsius.

[0016] Furthermore, the first inert solvent and the second inert solvent may be the same or different; the frequency range of the ultrasonic dispersion is 100 to 200 kHz; the ultrasonic dispersion time is 30 to 120 minutes, preferably 120 kHz, and more preferably 60 minutes.

[0017] The advantage of this invention over the prior art lies in:

[0018] 1. This method is simple to operate, operates under mild conditions, and is safe during the operation process.

[0019] 2. After treatment, the static water contact angle of α-aluminum trihydride increased from about 50° to 90-120°, and the hydrophobicity of the product was significantly improved.

[0020] 3. After treatment, the water absorption rate of α-aluminum trihydride was between 0.1% and 0.9% after 7 days at 30℃ and 75% relative humidity, and its storage stability and safety were also significantly improved.

[0021] This invention selects D 50 Carbon-based materials with a thickness not exceeding 5 μm are used as surface modifiers for α-aluminum trihydride. The carbon-based materials themselves are flammable and lubricating. After being dispersed in a first inert solvent, and after the first inert solvent is removed, they can be uniformly deposited and loaded on the surface of α-aluminum trihydride to achieve the effect of modifying the surface of α-aluminum trihydride. Then, an epoxy film-forming agent is used to form a film on the modified surface of α-aluminum trihydride to improve the hydrophobicity of α-aluminum trihydride. Attached Figure Description

[0022] These and / or other aspects and advantages of the present invention will become clearer and more readily understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 This is a SEM image of α-aluminum trihydride before treatment in Example 3 of the present invention;

[0024] Figure 2 This is a SEM image of α-aluminum trihydride after treatment in Example 3 of the present invention;

[0025] Figure 3 The static water contact angle test results of α-aluminum trihydride before treatment in Example 3 of this invention;

[0026] Figure 4The static water contact angle test results are for α-aluminum trihydride after treatment in Example 3 of this invention. Detailed Implementation Plan

[0027] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] 0.3 grams of D 50 Carbon black of 5 μm was added to petroleum ether at a concentration of 3% of the mass of α-aluminum trihydride, and ultrasonically dispersed for 30 minutes. Then, 10 g of D... 50 α-Aluminum trihydrogenate with a particle size of 15 μm was added to petroleum ether and ultrasonically dispersed at 100 kHz for 30 minutes with stirring. The petroleum ether was then removed by filtration. The obtained α-aluminum trihydrogenate was vacuum dried at 40 °C for 3 hours to obtain intermediate product C1. Then, 0.2 g of bisphenol A was dissolved in 20 g of pentane and stirred for 10 minutes. C1 was added, and the mixture was stirred for 30 minutes. 0.05 g of a polyamide curing agent with an amine value of 220 mg KOH / g was added, and the mixture was stirred for another 10 minutes. The solvent was then removed, and the treated α-aluminum trihydrogenate was dried at 30 °C under normal pressure for 24 hours. The mixture was then sieved to obtain hydrophobic α-aluminum trihydrogenate. Take 300 mg of sample and compress it into a tablet using a tablet press. Place the smooth side of the sample on a glass slide on the stage and measure it using a contact angle meter. The static water contact angle of α-aluminum trihydride before treatment is 51° and the static water contact angle after treatment is 93°. The water absorption rate is 0.8% after 7 days of storage at 30℃ and 75% relative humidity.

[0030] Example 2

[0031] 0.05 grams of D 50 0.5 μm graphene was added to pentane at a concentration of 0.05% of the mass of α-aluminum trihydride. The mixture was ultrasonically dispersed for 10 minutes, and then 100 g of D... 50α-Aluminum trihydrogenate with a particle size of 30 μm was added to cyclohexane and ultrasonically dispersed at 200 kHz for 120 minutes with stirring. The pentane was then removed by filtration. The obtained α-aluminum trihydrogenate was vacuum dried at 70 °C for 3 hours to obtain intermediate product C2. Then, 2 g of bisphenol A was dissolved in 140 g of gasoline and stirred for 30 minutes. C2 was added, and the mixture was stirred for another 30 minutes. 0.5 g of a polyamide curing agent with an amine value of 320 mg KOH / g was added, and the mixture was stirred for another 20 minutes. The solvent was then removed, and the treated α-aluminum trihydrogenate was dried at 70 °C under normal pressure for 3 hours and sieved to obtain hydrophobic α-aluminum trihydrogenate. Take 300 mg of sample and compress it into a tablet using a tablet press. Place the smooth side of the sample on a glass slide on the stage and measure it using a contact angle meter. The static water contact angle of α-aluminum trihydride before treatment is 51° and the static water contact angle after treatment is 98°. The water absorption rate is 0.6% after 7 days of storage at 30℃ and 75% relative humidity.

[0032] Example 3

[0033] 0.2 grams of D 50 0.1 μm carbon nanotubes were added to a mixed solvent of petroleum ether and n-hexane (solvent mass ratio 1:1), ultrasonically dispersed for 10 minutes, and then 20 g of D... 50 α-Aluminum trihydrogenate with a particle size of 15 μm was added to a mixed solvent of petroleum ether and n-hexane, and ultrasonically dispersed at 120 kHz for 60 minutes with stirring. The petroleum ether and n-hexane mixture was then removed by filtration. The obtained α-aluminum trihydrogenate was vacuum dried at 40 °C for 6 hours to obtain intermediate product C3. Then, 0.5 g of bisphenol A was dissolved in 40 g of petroleum ether and stirred for 10 minutes. C3 was added, and the mixture was stirred for 60 minutes. 0.1 g of a polyamide curing agent with an amine value of 350 mg KOH / g was added, and the mixture was stirred for another 15 minutes. The petroleum ether was then removed, and the treated α-aluminum trihydrogenate was dried at 40 °C under normal pressure for 8 hours and sieved to obtain hydrophobic α-aluminum trihydrogenate. 300 mg of the sample was tableted using a tablet press. SEM images of the α-aluminum trihydrogenate before and after treatment according to the method described in Example 3 are shown below. Figure 1 and Figure 2 As shown; the smooth surface of the sample was placed on a glass slide on the stage, and the static water contact angle of α-aluminum trihydride before and after treatment by the method described in Example 3 was measured using a contact angle meter. The results are shown below. Figure 3 and Figure 4 As shown, the static water contact angle of α-aluminum trihydride before treatment is 51°, and the static water contact angle after treatment is 116°. The water absorption rate is 0.2% after 7 days of storage at 30°C and 75% relative humidity.

[0034] Example 4

[0035] D 50 0.1 g carbon black and D for 3 μm50 0.2 g of carbon nanotubes with a diameter of 0.5 μm were added to a mixed solution of pentane and petroleum ether and ultrasonically dispersed for 10 minutes. Then, 30 g of D... 50 α-Aluminum trihydrogenate with a particle size of 15 μm was added to a mixed solution of pentane and petroleum ether, and ultrasonically dispersed at 140 kHz for 40 minutes with stirring. The pentane and petroleum ether were then removed by filtration. The obtained α-aluminum trihydrogenate was vacuum dried at 40 °C for 4 hours to obtain intermediate product C4. Then, 0.9 g of bisphenol A was dissolved in 50 g of gasoline and stirred for 10 minutes. C4 was added, and the mixture was stirred for 50 minutes. 0.35 g of a polyamide curing agent with an amine value of 250 mg KOH / g was added, and the mixture was stirred for another 15 minutes. The gasoline was then removed, and the treated α-aluminum trihydrogenate was dried at 40 °C under normal pressure for 8 hours and sieved to obtain hydrophobic α-aluminum trihydrogenate. Take 300 mg of sample and compress it into a tablet using a tablet press. Place the smooth side of the sample on a glass slide on the stage and measure it using a contact angle meter. The static water contact angle of α-aluminum trihydride before treatment is 51° and the static water contact angle after treatment is 110°. The water absorption rate is 0.4% after 7 days of storage at 30°C and 75% relative humidity.

[0036] Example 5

[0037] Add 0.05 g of carbon black to a mixed solution of n-hexane and petroleum ether. The amount of carbon black added is 0.5% of the mass of α-aluminum trihydride. Disperse ultrasonically for 10 minutes, then add 10 g of D... 50 α-Aluminum trihydrogenate with a particle size of 15 μm was added to a mixed solution of hexane and petroleum ether, and ultrasonically dispersed at 160 kHz for 50 minutes with stirring. Hexane and petroleum ether were then removed by filtration. The obtained α-aluminum trihydrogenate was vacuum dried at 40 °C for 4 hours to obtain intermediate product C5. Then, 0.75 g of bisphenol A was dissolved in 7.5 g of petroleum ether and stirred for 10 minutes. C5 was added, and the mixture was stirred for 50 minutes. 0.25 g of a polyamide curing agent with an amine value of 300 mg KOH / g was added, and the mixture was stirred for another 15 minutes. The petroleum ether was then removed, and the treated α-aluminum trihydrogenate was dried at 40 °C under normal pressure for 8 hours and sieved to obtain hydrophobic α-aluminum trihydrogenate. Take 300 mg of sample and compress it into a tablet using a tablet press. Place the smooth side of the sample on a glass slide on the stage and measure it using a contact angle meter. The static water contact angle of α-aluminum trihydride before treatment is 51° and the static water contact angle after treatment is 103°. The water absorption rate is 0.5% after 7 days of storage at 30°C and 75% relative humidity.

[0038] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for improving the hydrophobicity of α-aluminum trihydride, characterized in that, First, the surface modifier is dispersed in a first inert solvent to obtain an inert dispersion. Then, α-aluminum trihydrogenate is added to the inert dispersion, followed by ultrasonic dispersion, stirring, filtration to remove the solvent, and drying to obtain the treated α-aluminum trihydrogenate. Next, the organic film-forming agent is dissolved in a second inert solvent, and the above-treated α-aluminum trihydrogenate is added. After stirring, adding a curing agent, stirring again, filtration to remove the solvent, and drying, hydrophobic α-aluminum trihydrogenate is obtained. The surface modifier is a particulate material containing carbon, with a particle size D. 50 No more than 5μm; The carbon-containing particulate matter includes one or more of carbon black, graphene, and carbon nanotubes. The amount of the surface modifier is 0.05-3% of the mass of α-aluminum trihydride; the mass ratio of the surface modifier to the first inert solvent is 1:(10-100); The organic film-forming agent is bisphenol A type diglycidyl ether, and the mass ratio of the organic film-forming agent to the second inert solvent is 1:(10-100); The curing agent is a polyamide amine-based curing agent with an amine value ranging from 200 to 350 mg KOH / g, and the amount of curing agent added is 0.5% to 5% of the mass of α-aluminum trihydride; The particle size D of the α-aluminum trihydride 50 It is distributed in the range of 5–350 μm.

2. The method for improving the hydrophobicity of α-aluminum trihydride according to claim 1, characterized in that, The solvent removal by filtration and the drying process are carried out at temperatures ranging from 30 to 70°C for 2 to 48 hours.

3. The method for improving the hydrophobicity of α-aluminum trihydride according to claim 2, characterized in that, The amount of the surface modifier is 0.1% of the mass of α-aluminum trihydride; the mass ratio of the surface modifier to the first inert solvent is 1:

50. The mass ratio of the organic film-forming agent to the second inert solvent is 1:70; The curing agent has an amine value ranging from 220 to 320 mg KOH / g, and its addition amount is 1% of the mass of α-aluminum trihydride; The particle size D of the α-aluminum trihydride 50 Distributed in the range of 15–30 μm; The solvent removal process and the drying process are both carried out at a temperature of 40°C for 24 hours.

4. The method for improving the hydrophobicity of α-aluminum trihydride according to claim 1, characterized in that, The first and second inert solvents both refer to alkanes that are inert when mixed with α-aluminum trihydride and have a boiling point of no more than 100°C at normal pressure.

5. The method for improving the hydrophobicity of α-aluminum trihydride according to claim 1 or 4, characterized in that, The first inert solvent and the second inert solvent are both selected from one or more of pentane, n-hexane, cyclohexane, and petroleum ether 60-90.

6. The method for improving the hydrophobicity of α-aluminum trihydride according to claim 1, characterized in that, The first inert solvent may be the same as or different from the second inert solvent; the frequency range of the ultrasonic dispersion is 100-200 kHz; and the ultrasonic dispersion time is 30-120 minutes.

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