Preparation method of composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen

Abstract

The present invention discloses a method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen. The method comprises: hydrolyzing H2O and tetraethyl orthosilicate under the action of an acidic catalyst, stirring in a water bath to obtain a partially hydrolyzed SiO2 aerogel precursor solution; adding CaCl2 powder to 1,4-dioxane and ultrasonically treating the solution to obtain a dispersion; adding an organic hydrogen absorber and a catalyst to the dispersion and ultrasonically treating the solution to obtain a mixed solution A; mixing the SiO2 aerogel precursor solution with the mixed solution A to obtain a mixed solution B; dropwise adding deionized water and aqueous ammonia to the mixed solution B, ultrasonically treating the solution, gelling the solution, and then treating the solution in a water bath to obtain a wet gel; freezing the wet gel with liquid nitrogen, placing the solution in a freeze dryer, and placing the resulting solid powder in an oven to obtain a composite aerogel material capable of absorbing moisture and irreversibly absorbing hydrogen. The method features mild reaction conditions, a simple and easy-to-control process, and a high sample yield. The resulting composite aerogel not only has a high specific surface area but also can efficiently absorb both water vapor and hydrogen.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite functional aerogel preparation, and more specifically, relates to a method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen. Background Art

[0002] For sealed and vacuum systems containing electronic components, prolonged storage and use can lead to increased humidity within the system due to gas permeation, while aging organic materials can also produce small amounts of hydrogen. Water vapor can corrode metal materials within the system, so increased humidity can shorten system life and reduce reliability. Hydrogen is a flammable gas that explodes at concentrations exceeding 4% by volume in air. It can also cause hydrogen embrittlement with metals, degrading their performance. Therefore, to extend the lifespan and improve the reliability of electronic systems, it is essential to remove these two harmful gases: water vapor and hydrogen.

[0003] Materials that have both moisture and hydrogen absorption properties can be widely used in the industrial field. They can be used in various vacuum devices to improve the vacuum degree and service life. They can be used in sealing systems to protect electronic devices from corrosion by water vapor and hydrogen. They can also be used for the purification of high-purity gases. Existing moisture-absorbing materials are mainly metal halides and super absorbent resins. Currently, common hydrogen-absorbing materials are divided into reversible hydrogen-absorbing materials and irreversible hydrogen-absorbing materials. Reversible hydrogen-absorbing materials include: porous carbon, hydrogen-absorbing alloys, metal-organic framework materials, etc.; irreversible hydrogen-absorbing materials are mainly organic hydrogen absorbers containing unsaturated carbon-carbon bonds. Organic hydrogen absorbers can undergo hydrogenation reactions with hydrogen under the action of a catalyst (Pd), converting alkynes or alkenes into alkenes or alkane organics, thereby achieving irreversible hydrogen absorption.

[0004] US 4405487 discloses a method for preparing a composite material capable of simultaneously absorbing moisture and hydrogen. The selected moisture-absorbing material is an easily oxidizable metal (such as Zn), and the hydrogen-absorbing material is an organic compound containing unsaturated carbon-carbon bonds (1,4-diphenylbutadiene, DPB). The moisture-absorbing and hydrogen-absorbing process described in this patent is as follows: first, the easily oxidizable metal reacts with water to form a metal oxide and hydrogen. Then, the organic hydrogen-absorbing agent undergoes a hydrogenation reaction with hydrogen in the presence of a catalyst, thereby achieving the moisture-absorbing and hydrogen-absorbing purpose. This patent uses a powder mixing and pressing method to combine the easily oxidizable metal and the organic hydrogen-absorbing agent. The moisture-absorbing and hydrogen-absorbing composite material produced by this method does not have a porous structure and lacks atmosphere diffusion channels, resulting in low gas adsorption efficiency. Furthermore, the reaction of the easily oxidizable metal with water produces byproducts. The selected hydrogen-absorbing material, DPB, has a melting point of only 87°C, thus having certain limitations in practical applications. Summary of the Invention

[0005] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0006] In order to achieve these objects and other advantages according to the present invention, a method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen is provided, comprising the following steps:

[0007] Step 1: Using tetraethyl orthosilicate as a raw material and anhydrous ethanol as a solvent, a hydrolysis reaction is carried out in the presence of an acidic catalyst so that the molar ratio of H2O to tetraethyl orthosilicate is less than the stoichiometric ratio, and then the mixture is placed in a 38°C water bath and stirred for 30 minutes to obtain a partially hydrolyzed SiO2 aerogel precursor solution;

[0008] Step 2: Weigh CaCl2 powder, add 1,4-dioxane and perform ultrasonic treatment to disperse it evenly to obtain a dispersion;

[0009] Step 3: adding a certain mass ratio of an organic hydrogen absorber and a catalyst to the dispersion in step 2, and subjecting them to ultrasonic treatment to complete dissolution to obtain a mixed solution A;

[0010] Step 4: The SiO2 aerogel precursor solution prepared in step 1 and the mixed solution A prepared in step 3 are mixed and stirred uniformly in a certain volume ratio to obtain a mixed solution B;

[0011] Step 5: Add a small amount of deionized water and ammonia water to the mixed solution B prepared in step 4, and then ultrasonicate the mixed solution B for a certain period of time to make it gel. After gelation, treat the mixed solution in a 50°C water bath to completely gelate it to obtain a wet gel;

[0012] Step 6: Use liquid nitrogen to freeze the wet gel obtained in step 5 to completely solidify the solvent in the wet gel, then put it into a freeze dryer for treatment, and put the obtained solid powder into an 80°C oven for drying, finally obtaining a composite aerogel material that can absorb moisture and irreversibly absorb hydrogen.

[0013] Preferably, in the step 1, the mass ratio of ethyl orthosilicate, anhydrous ethanol, H2O and acidic catalyst is 1:7:2:10. -5 .

[0014] Preferably, in step 1, the acidic catalyst is HCl.

[0015] Preferably, in the step 2, the mass fraction of the CaCl2 powder in the dispersion is 5 to 10%.

[0016] Preferably, in step three, the organic hydrogen absorber is 1,4-diphenylethynylbenzene, the catalyst is bis(dibenzylideneacetone palladium), the mass ratio of 1,4-diphenylethynylbenzene to bis(dibenzylideneacetone palladium) is 5:2, and the total mass fraction of 1,4-diphenylethynylbenzene and bis(dibenzylideneacetone palladium) in the mixed solution A is 5 to 20%.

[0017] Preferably, in the step 4, the volume ratio of the SiO2 aerogel precursor solution to the mixed solution A is 1:1-5.

[0018] Preferably, in step 5, the volume ratio of mixed solution B to deionized water is 100:1-3; the volume ratio of mixed solution B to ammonia water is 100:0.5-1, the ultrasonic treatment time is 30-60s, and the 50°C water bath treatment time is 3-5h.

[0019] Preferably, in step six, the liquid nitrogen freezing treatment time is 10 minutes.

[0020] The present invention includes at least the following beneficial effects: 1,4-dioxane is used as a solvent and dispersant to simultaneously load a hygroscopic material, a hydrogen absorbing material, and a catalyst during the SiO2 gelation process, and finally, freeze-drying is performed to produce a SiO2-loaded hygroscopic and hydrogen absorbing composite aerogel. The hygroscopic material, organic hydrogen absorbing agent, and catalyst are combined within the SiO2 aerogel structure. The SiO2 aerogel not only possesses a certain gas adsorption capacity, but its nanoporous network also serves as a diffusion channel for the atmosphere, further facilitating the efficient adsorption of water vapor and hydrogen by the hygroscopic and hydrogen absorbing materials. CaCl2, as a hygroscopic material, absorbs water vapor to form a stable crystalline hydrate without any other byproducts. The DEB organic hydrogen absorbing agent has a higher melting point (179°C) and is more stable than DPB. Compared to traditional palladium-carbon catalysts, the selected Pd-dba catalyst has a melting point of only 150°C and is soluble in solvents, making it more conducive to compounding with the hydrogen absorbing agent. The preparation method of the present invention has mild reaction conditions, simple and easy-to-control process, high sample yield, and the prepared composite aerogel not only has a high specific surface area but can also efficiently adsorb water vapor and hydrogen at the same time.

[0021] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The nitrogen adsorption test results and pore size distribution diagram of the composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen provided in Example 1 of the present invention;

[0023] Figure 2 This is a moisture absorption test chart of the composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen provided in Example 1 of the present invention under the conditions of 25°C and 60% RH;

[0024] Figure 3 This is a hydrogen absorption test chart of the composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen provided in Example 1 of the present invention under conditions of 25° C. and 1 bar of pure hydrogen. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0026] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0027] Example 1

[0028] This embodiment discloses a method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen, comprising the following steps:

[0029] Step 1: Prepare SiO2 aerogel precursor solution using tetraethyl orthosilicate (TEOS) as raw material, C2H5OH as solvent, and HCl as catalyst;

[0030] Step 2: Add 5% by mass of CaCl2 powder to 1,4-dioxane and sonicate to form a uniform dispersion;

[0031] Step 3: Add 10% by mass of 1,4-diphenylethynylbenzene (DEB) and bis(dibenzylideneacetone) palladium (Pd-dba) powder to the dispersion, with a DEB to Pd-dba mass ratio of 5:2, and then sonicate to dissolve the mixture to form a uniform mixed solution A;

[0032] Step 4: Take 2 ml of the SiO2 aerogel precursor solution prepared in step 1 and 8 ml of the mixed solution A prepared in step 3, mix and stir evenly to obtain a mixed solution B;

[0033] Step 5: Add 300 μl of deionized water and 100 μl of ammonia solution to the mixed solution B prepared in step 4, and then ultrasonicate for 30 seconds to gel. After gelation, treat in a 50°C water bath for 3 hours to completely gel.

[0034] Step 6: Use liquid nitrogen to freeze the wet gel obtained in step 5 for 10 minutes to completely solidify its solvent, then put it into a freeze dryer for treatment, and put the obtained solid powder into an 80°C oven for drying treatment to finally obtain a composite aerogel material that can absorb moisture and irreversibly absorb hydrogen.

[0035] In this embodiment, the molar ratio of the SiO2 aerogel precursor solution during preparation is n(TEOS):n(C2H5OH):n(H2O):n(HCl)=1:7:2:10. -5 (mol).

[0036] In this example, 1,4-dioxane was used as a solvent and dispersant to simultaneously load CaCl2, DEB, and Pd-dba during the SiO2 gelation process. Finally, a SiO2-loaded CaCl2, DEB, and Pd-dba composite aerogel was produced by freeze-drying. The incorporation of CaCl2, DEB, and Pd-dba into the SiO2 aerogel structure not only imparts a certain gas adsorption capacity, but also allows its nanoporous network to serve as a diffusion channel for the atmosphere, further facilitating the efficient adsorption of water vapor and hydrogen by moisture-absorbing and hydrogen-absorbing materials.

[0037] In this embodiment, the nitrogen adsorption test results and pore size distribution of the composite aerogel material capable of absorbing moisture and irreversibly absorbing hydrogen are as follows: Figure 1 As shown in the figure, it can be observed that although moisture-absorbing and hydrogen-absorbing materials are added, the nitrogen adsorption curve of the composite aerogel still retains the adsorption characteristics of the porous structure of the aerogel, and its specific surface area is as high as 517m 2 / g, indicating that the moisture-absorbing and hydrogen-absorbing materials have no significant effect on the porous structure of the aerogel. From the pore size distribution diagram, it can be observed that the pore size of the composite aerogel is mainly distributed below 5nm.

[0038] In this embodiment, the moisture absorption performance of the composite aerogel material capable of absorbing moisture and irreversibly absorbing hydrogen at 25°C and 60% RH is as follows: Figure 2 As shown in the figure, it can be observed that the composite aerogel has a rapid moisture absorption capability, and basically reaches the saturated capacity in 30 minutes, and the saturated moisture absorption reaches 28 wt%.

[0039] In this embodiment, the prepared composite aerogel material capable of absorbing moisture and irreversibly absorbing hydrogen has a hydrogen absorption performance of 25°C and 1 bar pure hydrogen. Figure 3 As shown in the figure, it can be observed that the hydrogen absorption rate of the composite aerogel is fast within 10 hours, and the hydrogen absorption amount reaches 24 ml / g at 10 hours. The hydrogen absorption rate decreases slowly after 10 hours, and the hydrogen absorption amount reaches 40 ml / g at 140 hours.

[0040] In this embodiment, the moisture absorption and hydrogen absorption properties of the prepared composite aerogel material capable of absorbing moisture and irreversibly absorbing hydrogen do not affect each other. After saturation of moisture absorption, it can irreversibly absorb hydrogen, or after saturation of hydrogen absorption, it can continue to absorb moisture, or the moisture absorption and hydrogen absorption processes can be carried out simultaneously.

[0041] Example 2

[0042] This embodiment discloses a method for preparing a composite aerogel that can absorb moisture and irreversibly absorb hydrogen. The method differs from Example 1 in that: in step 2, the mass fraction of CaCl2 added to 1,4-dioxane is 6%; in step 3, the mass fraction of a mixed powder of 1,4-diphenylethynylbenzene (DEB) and bis(dibenzylideneacetone) palladium (Pd-dba) is added to the dispersion liquid; in step 4, 5 ml of the SiO2 aerogel precursor solution prepared in step 1 and 5 ml of the mixed solution A prepared in step 3 are mixed and stirred to obtain a mixed solution B; in step 5, 100 ul of deionized water and 50 ul of ammonia water are respectively added dropwise to the mixed solution B.

[0043] Example 3

[0044] This embodiment discloses a method for preparing a composite aerogel that can absorb moisture and irreversibly absorb hydrogen. The method differs from Example 1 in that: in step 2, the mass fraction of CaCl2 added to 1,4-dioxane is 7%; in step 3, the mass fraction of a mixed powder of 1,4-diphenylethynylbenzene (DEB) and bis(dibenzylideneacetone) palladium (Pd-dba) is added to the dispersion liquid; in step 4, 3 ml of the SiO2 aerogel precursor solution prepared in step 1 and 6 ml of the mixed solution A prepared in step 3 are mixed and stirred to obtain a mixed solution B; in step 5, 150 ul of deionized water and 60 ul of ammonia water are respectively added dropwise to the mixed solution B.

[0045] Example 4

[0046] This embodiment discloses a method for preparing a composite aerogel that can absorb moisture and irreversibly absorb hydrogen. The method differs from Example 1 in that: in step 2, the mass fraction of CaCl2 added to 1,4-dioxane is 8%; in step 3, the mass fraction of a mixed powder of 1,4-diphenylethynylbenzene (DEB) and bis(dibenzylideneacetone) palladium (Pd-dba) is added to the dispersion liquid; in step 4, 2.5 ml of the SiO2 aerogel precursor solution prepared in step 1 and 7.5 ml of the mixed solution A prepared in step 3 are mixed and stirred to obtain a mixed solution B; in step 5, 200 ul of deionized water and 70 ul of ammonia water are respectively added dropwise to the mixed solution B.

[0047] Example 5

[0048] This embodiment discloses a method for preparing a composite aerogel that can absorb moisture and irreversibly absorb hydrogen. The method differs from Example 1 in that: in step 2, the mass fraction of CaCl2 added to 1,4-dioxane is 9%; in step 3, the mass fraction of a mixed powder of 1,4-diphenylethynylbenzene (DEB) and bis(dibenzylideneacetone) palladium (Pd-dba) is added to the dispersion liquid; in step 4, 2 ml of the SiO2 aerogel precursor solution prepared in step 1 and 10 ml of the mixed solution A prepared in step 3 are mixed and stirred to obtain a mixed solution B; in step 5, 250 ul of deionized water and 80 ul of ammonia water are respectively added dropwise to the mixed solution B.

[0049] Example 6

[0050] This embodiment discloses a method for preparing a composite aerogel that can absorb moisture and irreversibly absorb hydrogen. The method differs from Example 1 in that: in step 2, the mass fraction of CaCl2 added to 1,4-dioxane is 10%; in step 3, the mass fraction of a mixed powder of 1,4-diphenylethynylbenzene (DEB) and bis(dibenzylideneacetone) palladium (Pd-dba) is added to the dispersion liquid; in step 4, 3 ml of the SiO2 aerogel precursor solution prepared in step 1 and 7 ml of the mixed solution A prepared in step 3 are mixed and stirred uniformly to obtain a mixed solution B; and in step 5, 90 ul of ammonia water is added dropwise to the mixed solution B.

[0051] The number of devices and processing scales described herein are intended to simplify the description of the present invention. Applications, modifications, and variations of the present invention will be readily apparent to those skilled in the art.

[0052] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen, characterized in that: The following steps are involved: Step 1: Using tetraethyl orthosilicate as a raw material and anhydrous ethanol as a solvent, a hydrolysis reaction is carried out in the presence of an acidic catalyst so that the molar ratio of H2O to tetraethyl orthosilicate is less than the stoichiometric ratio, and then the mixture is placed in a 38°C water bath and stirred for 30 minutes to obtain a partially hydrolyzed SiO2 aerogel precursor solution; Step 2: Weigh CaCl2 powder, add 1,4-dioxane and perform ultrasonic treatment to disperse it evenly to obtain a dispersion; Step 3: adding a certain mass ratio of an organic hydrogen absorber and a catalyst to the dispersion in step 2, and performing ultrasonic treatment to completely dissolve the organic hydrogen absorber to obtain a mixed solution A; wherein the organic hydrogen absorber is 1,4-diphenylethynylbenzene; Step 4: The SiO2 aerogel precursor solution prepared in step 1 and the mixed solution A prepared in step 3 are mixed and stirred uniformly in a certain volume ratio to obtain a mixed solution B; Step 5: Add a small amount of deionized water and ammonia water to the mixed solution B prepared in step 4, and then ultrasonicate the mixed solution B for a certain period of time to make it gel. After gelation, treat the mixed solution in a 50°C water bath to completely gelate it to obtain a wet gel; Step 6: Use liquid nitrogen to freeze the wet gel obtained in step 5 to completely solidify the solvent in the wet gel, then put it into a freeze dryer for treatment, and put the obtained solid powder into an 80°C oven for drying, finally obtaining a composite aerogel material that can absorb moisture and irreversibly absorb hydrogen.

2. The method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen according to claim 1, wherein: In the step 1, the mass ratio of ethyl orthosilicate, anhydrous ethanol, H2O and acidic catalyst is 1:7:2:

10. -5 .

3. The method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen according to claim 1, wherein: In the step 1, the acidic catalyst is HCl.

4. The method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen according to claim 1, wherein: In the step 2, the mass fraction of the CaCl2 powder in the dispersion is 5-10%.

5. The method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen according to claim 1, wherein: In the step 3, the catalyst is bis(dibenzylideneacetonepalladium), the mass ratio of 1,4-diphenylethynylbenzene to bis(dibenzylideneacetonepalladium) is 5:2, and the total mass fraction of 1,4-diphenylethynylbenzene and bis(dibenzylideneacetonepalladium) in the mixed solution A is 5-20%.

6. The method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen according to claim 1, wherein: In the step 4, the volume ratio of the SiO2 aerogel precursor solution to the mixed solution A is 1:1-5.

7. The method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen according to claim 1, wherein: In the step 5, the volume ratio of the mixed solution B to deionized water is 100:1-3; the volume ratio of the mixed solution B to ammonia water is 100:0.5-1, the ultrasonic treatment time is 30-60 seconds, and the 50° C. water bath treatment time is 3-5 hours.

8. The method for preparing a composite aerogel capable of absorbing moisture and irreversibly absorbing hydrogen according to claim 1, wherein: In step 6, the liquid nitrogen freezing treatment time is 10 minutes.

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