Preparation method and application of MgH2-Pb-coated ZrO2-C nano composite hydrogen storage material

Abstract

The invention is applicable to the technical field of solid hydrogen storage, and provides a preparation method and application of an MgH2-Pb-ZrO2-C nano-composite hydrogen storage material. Zr-Pb-MOF is synthesized through a UIO-66 template method, bimetal nanoparticles obtained after Zr-Pb-MOF pyrolysis are fully mixed with MgH2, MgH2-Pb-ZrO2-C is prepared, and the hydrogen adsorption and desorption amount of the MgH2-Pb-ZrO2-C can reach 6.98 wt%. According to the material, an MOFs derivative is used as a buffer material to prevent agglomeration in ball milling and dehydrogenation processes, and the catalytic effect of MOFs and the synergistic effect of nano-constraint are fully utilized to improve electron transfer in the hydrogen atom adsorption / desorption process. The specific surface area of the nano-composite hydrogen storage material can be increased by increasing the doping content of Pb (NO3) 2, and meanwhile, the hydrogen storage capacity of the material can be remarkably improved by combining pyrolysis treatment; the preparation method is simple and feasible and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state hydrogen storage, and particularly relates to a preparation method and application of a MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material. Background Art

[0002] In the field of solid-state hydrogen storage, researchers are working on developing hydrogen storage materials with high hydrogen storage capacity, excellent cycle stability, and suitability for large-scale production. However, these materials still face multiple technical challenges in practical applications. First, the preparation processes of most current solid-state hydrogen storage materials are complex and costly, which greatly limits their application in industrial production. In addition, the performance of many existing materials will degrade significantly after long-term cyclic use, resulting in a reduction in the cycle service life and reliability of the materials in practical applications. This performance decay is mainly attributed to the changes in the internal structure of the materials during multiple hydrogen absorption and desorption processes, leading to a gradual decrease in their hydrogen storage efficiency. Another prominent technical problem is that during the carbonization or activation stage, certain heteroatoms will catalyze unnecessary reactions, making the carbon framework unstable and causing partial or complete collapse of the porous structure. This collapse may be due to the introduction of strain or defects in the carbon lattice, resulting in a significant reduction in the surface area of the material.

[0003] To address these challenges, researchers are exploring various strategies. Among them, metal-organic frameworks (MOFs) have unique morphological and compositional advantages, such as ultra-high porosity and uniformly dispersed metal nodes at the atomic scale, providing abundant anchoring sites for MgH 2 . Its relatively stable carbon framework and porous structure are conducive to gas diffusion and electron transfer during hydrogen atom adsorption / desorption processes. In addition, MOFs also have the advantages of adjustable pore structure, pore size, and extremely high specific surface area. These characteristics enable them to fully utilize the advantages of the high specific surface area of adsorbent materials. Therefore, the hydrogen storage system based on MOFs catalyzing magnesium hydride (MgH 2 ) shows great application potential in solid-state hydrogen storage. Although MOFs have significant advantages in specific surface area, their hydrogen storage capacity and cycle stability need to be further optimized. The high specific surface area of MOFs mainly stems from their complex pore structure. The internal specific surface area formed inside these pores theoretically increases the contact area with gas. However, this increases the difficulty of loading metal single atoms into the pores. During the loading process, metal single atoms need to overcome the limitations of the pore structure on mass transfer, which may lead to low loading efficiency and uneven distribution. Moreover, the loading process is prone to pore blockage or excessive structural stress, resulting in the collapse of the porous structure, damaging the overall performance and stability of the material, and further severely limiting the solid-state hydrogen storage capacity. Therefore, the present invention proposes a MgH 2-Pb@ZrO 2 Preparation method and application of -C nanocomposite hydrogen storage material Summary of the Invention

[0004] The purpose of the present invention is to provide a MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material and its preparation method and application, aiming to solve the problems proposed in the above background technology

[0005] The purpose of the present invention is achieved through the following technical solutions

[0006] A preparation method of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material, comprising the following steps

[0007] Step S1: Synthesize Pb-doped Zr-Pb-MOF by UIO-66 template method

[0008] Weigh ZrCl 4 and Pb(NO 3 ) 2 , and add them to N,N-dimethylformamide, stir to obtain solution A; dissolve terephthalic acid in solution A, and perform ultrasonic treatment after mixing to obtain solution B; transfer solution B to a separating funnel, and drop it into glacial acetic acid, continuously stir to obtain solution C; transfer solution C to a hydrothermal autoclave, heat it, wash the product with DMF and ethanol, and vacuum dry the product overnight to obtain Zr-Pb-MOF

[0009] Step S2: Preparation of bimetallic nanoparticles

[0010] Place the Zr-Pb-MOF prepared in step S1 in a quartz boat, pyrolyze it under N 2 atmosphere to obtain Pb@ZrO 2 -C nanoparticles

[0011] Step S3: Preparation of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material

[0012] Weigh MgH 2 and the Pb@ZrO 2 -C prepared in step S2, add absolute ethanol, perform ball milling treatment, and vacuum dry the ball-milled mixture overnight to finally obtain a uniform MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material

[0013] Further, the specific process of step S1 is as follows:

[0014] Weigh ZrCl 4 and Pb(NO 3 ) 2 , and add them to 20 - 25 mL of N,N - dimethylformamide, stir for 15 - 20 min to obtain solution A; dissolve 1 - 1.2 mmol of terephthalic acid in solution A, mix and then ultrasonically treat for 30 min to obtain solution B; transfer solution B to a separating funnel and drop it into 2.0 - 2.4 mL of glacial acetic acid at a rate of 2 - 3 drops per second, continuously stir for 30 min to obtain solution C; transfer solution C to a hydrothermal reactor, heat at 120 - 140 °C for 20 - 24 h, wash the product with DMF and ethanol, and vacuum dry overnight at 60 - 70 °C to prepare Zr - Pb - MOF.

[0015] Further, in step S1, the molar ratio of ZrCl 4 and Pb(NO 3 ) 2 is 1:1 - 1:1.4.

[0016] Further, the specific process of step S2 is as follows:

[0017] Place the Zr - Pb - MOF prepared in step S1 in a quartz boat, under N 2 atmosphere, heat up to 600 - 800 °C at a heating and cooling rate of 1 - 5 °C / min, pyrolyze for 3 h to prepare Pb@ZrO 2 -C nanoparticles.

[0018] Further, the specific process of step S3 is as follows:

[0019] Weigh MgH 2 and the Pb@ZrO 2 -C prepared in step S2, add absolute ethanol, ball mill for 30 min, vacuum dry the ball - milled mixture overnight at 60 - 70 °C, and finally prepare a uniform MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material.

[0020] Further, in step S3, the mass ratio of MgH 2 and Pb@ZrO 2 -C is 10:1 - 15:1.

[0021] A kind of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material prepared by the preparation method as described above to obtain MgH 2-Pb@ZrO 2 -C nanocomposite hydrogen storage material.

[0022] The present invention has the following beneficial effects:

[0023] 1. The present invention successfully prepared MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material, which exhibits excellent hydrogen storage performance, and its hydrogen absorption and desorption capacity can reach 6.98 wt%.

[0024] 2. By increasing the doping content of Pb(NO 3 ) 2 of the present invention, the specific surface area of the nanocomposite hydrogen storage material can be effectively increased. At the same time, combined with pyrolysis treatment, the hydrogen storage capacity of the nanocomposite hydrogen storage material can be significantly improved.

[0025] 3. The preparation method of the present invention is simple and easy to implement, and is suitable for large-scale production. Brief Description of the Drawings

[0026] Figure 1 is the TEM image of Zr-Pb-MOF.

[0027] Figure 2 is the TEM image of Pb@ZrO 2 -C nanoparticles. Detailed Embodiments

[0028] For a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0029] The present invention provides a preparation method of a MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material, comprising the following steps:

[0030] Step S1: Synthesize Pb-doped Zr-Pb-MOF by UIO-66 template method;

[0031] Weigh ZrCl 4 and Pb(NO 3 ) 2(With a molar ratio of 1:1 - 1:1.4), add it to 20 - 25 mL of N,N-dimethylformamide (DMF), stir for 15 - 20 min to obtain Solution A; dissolve 1 - 1.2 mmol of terephthalic acid (TAA) in Solution A, and after mixing, perform ultrasonic treatment for 30 min to obtain Solution B; transfer Solution B to a separating funnel, and drop it into 2.0 - 2.4 mL of glacial acetic acid at a rate of 2 - 3 drops per second, while continuously stirring for 30 min to obtain Solution C; transfer Solution C to a hydrothermal autoclave, heat it at 120 - 140 °C for 20 - 24 h, wash the product with DMF and ethanol, and vacuum dry it at 60 - 70 °C overnight to obtain Zr-Pb-MOF.

[0032] Step S2: Preparation of bimetallic nanoparticles;

[0033] Place the Zr-Pb-MOF prepared in Step S1 in a quartz boat, under N 2 atmosphere, heat it to 600 - 800 °C at a heating and cooling rate of 1 - 5 °C / min, and pyrolyze for 3 h to obtain Pb@ZrO 2 -C nanoparticles.

[0034] Step S3: Preparation of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material;

[0035] Weigh MgH with a mass ratio of 10:1 - 15:1 2 and the Pb@ZrO prepared in Step S2 2 -C, add absolute ethanol, and ball mill for 30 min. Vacuum dry the ball-milled mixture at 60 - 70 °C overnight to finally obtain a uniform MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material.

[0036] In the embodiment of the present invention, the present invention first synthesizes Pb-doped Zr-Pb-MOF by using the UIO-66 template method. The bimetallic nanoparticles after pyrolysis of Zr-Pb-MOF are fully mixed with MgH 2 to prepare MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material. This material can use MOFs derivatives as buffer materials to prevent agglomeration during ball milling and dehydrogenation, and make full use of the synergistic effect of the catalytic effect of MOFs and nano-constraint, thereby enhancing the electron transfer during the hydrogen atom adsorption / desorption process.

[0037] Now, the present invention will be further described in combination with specific embodiments.

[0038] Example 1: The present invention provides a kind of MgH2 -Pb@ZrO 2 Preparation method of MgH

[0039] Step S1: Synthesize Pb-doped Zr-Pb-MOF by UIO-66 template method;

[0040] Weigh ZrCl 4 and Pb(NO 3 ) 2 (with a molar ratio of 1:1), add them to 20 mL of N,N-dimethylformamide (DMF), stir for 20 min to obtain solution A; dissolve 1.2 mmol of terephthalic acid (TAA) in solution A, ultrasonically treat the mixture for 30 min after mixing to obtain solution B; transfer solution B to a separating funnel, drop it into 2.4 mL of glacial acetic acid at a rate of 3 drops per second, continuously stir for 30 min to obtain solution C; transfer solution C to a hydrothermal reactor, heat it at 120 °C for 24 h, wash the product with DMF and ethanol, and vacuum dry it overnight at 60 °C to obtain Zr-Pb-MOF.

[0041] Step S2: Preparation of bimetallic nanoparticles;

[0042] Place the Zr-Pb-MOF prepared in step S1 in a quartz boat, under N 2 atmosphere, heat it to 800 °C at a heating and cooling rate of 2 °C / min, and pyrolyze for 3 h to obtain Pb@ZrO 2 -C nanoparticles.

[0043] Step S3: Preparation of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material;

[0044] Weigh MgH 2 and the Pb@ZrO 2 -C prepared in step S2 with a mass ratio of 10:1, add 5 mL of absolute ethanol, ball mill for 30 min, vacuum dry the ball-milled mixture overnight at 60 °C, and finally obtain a uniform MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material.

[0045] Example 2: The present invention provides a preparation method of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material, including the following steps:

[0046] Step S1: Synthesize Pb-doped Zr-Pb-MOF by UIO-66 template method;

[0047] Weigh ZrCl 4 and Pb(NO 3 ) 2 (with a molar ratio of 1:1.2), add them to 25 mL of N,N-dimethylformamide (DMF), stir for 20 min to obtain solution A; dissolve 1.2 mmol of terephthalic acid (TAA) in solution A, mix and then perform ultrasonic treatment for 30 min to obtain solution B; transfer solution B to a separating funnel and drip it into 2.4 mL of glacial acetic acid at a rate of 3 drops per second, continuously stir for 30 min to obtain solution C; transfer solution C to a hydrothermal reactor, heat it at 120 °C for 24 h, wash the product with DMF and ethanol, and vacuum dry it at 60 °C overnight to prepare Zr-Pb-MOF.

[0048] Step S2: Preparation of bimetallic nanoparticles;

[0049] Place the Zr-Pb-MOF prepared in Step S1 in a quartz boat, under N 2 atmosphere, heat it to 800 °C at a heating and cooling rate of 2 °C / min, and pyrolyze for 3 h to prepare Pb@ZrO 2 -C nanoparticles.

[0050] Step S3: Preparation of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material;

[0051] Weigh MgH 2 and Pb@ZrO 2 -C prepared in Step S2 with a mass ratio of 10:1, add 5 mL of absolute ethanol, ball mill for 30 min, vacuum dry the ball-milled mixture at 60 °C overnight, and finally prepare a uniform MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material.

[0052] Example 3: The present invention provides a method for preparing a MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material, including the following steps:

[0053] Step S1: Synthesis of Pb-doped Zr-Pb-MOF by UIO-66 template method;

[0054] Weigh ZrCl 4 and Pb(NO 3 ) 2(With a molar ratio of 1:1.4), it was added to 25 mL of N,N-dimethylformamide (DMF), and stirred for 20 min to obtain Solution A; 1.2 mmol of terephthalic acid (TAA) was dissolved in Solution A, and after mixing, it was ultrasonically treated for 30 min to obtain Solution B; Solution B was transferred to a separating funnel and dropped into 2.0 mL of glacial acetic acid at a rate of 3 drops per second, with continuous stirring for 30 min to obtain Solution C; Solution C was transferred to a hydrothermal autoclave and heated at 120 °C for 24 h, the product was washed with DMF and ethanol, and vacuum dried at 60 °C overnight to prepare Zr-Pb-MOF.

[0055] Step S2: Preparation of bimetallic nanoparticles;

[0056] The Zr-Pb-MOF prepared in Step S1 was placed in a quartz boat, and under N 2 atmosphere, it was heated to 800 °C at a heating and cooling rate of 2 °C / min and pyrolyzed for 3 h to prepare Pb@ZrO 2 -C nanoparticles.

[0057] Step S3: Preparation of MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material;

[0058] Weigh MgH with a mass ratio of 10:1 2 and the Pb@ZrO prepared in Step S2 2 -C, and add 5 mL of absolute ethanol, ball mill for 30 min, and vacuum dry the ball-milled mixture at 60 °C overnight to finally prepare a uniform MgH 2 -Pb@ZrO 2 -C nanocomposite hydrogen storage material.

[0059] Comparative Example 1: The difference between this comparative example and Example 3 is that Pb(NO 3 ) 2 is not added during the synthesis of MOF (that is, when performing Step S1 of Example 3, Pb(NO 3 ) 2 ) is not added), and UiO-66 is generated.

[0060] Comparative Example 2: The difference between this comparative example and Example 3 is that Zr-Pb-MOF is not pyrolyzed (that is, Step S2 in Example 3 is not performed), and it is directly ball milled with MgH 2 to prepare a composite material.

[0061] The separation performance tests of the samples prepared in Examples 1-3 and Comparative Examples 1-2 are as follows:

[0062] The obtained samples were subjected to nitrogen adsorption - desorption tests under isothermal conditions and hydrogen storage performance tests at the temperature of liquid nitrogen (77K) and a hydrogen pressure of 70 Pa. The test results of specific surface area and hydrogen adsorption / desorption amount were obtained, as shown in Table 1.

[0063] Table 1 Hydrogen Storage Performance Test

[0064] <![CDATA[Specific surface area (m 2 / g)]]> Hydrogen adsorption / desorption amount (wt%) Example 1 1205 2.26 Example 2 1318 2.04 Example 3 1409 6.98 Comparative Example 1 1114 1.14 Comparative Example 2 2100 0.39

[0065] It can be seen from the data in Table 1 that the sample obtained in Example 3 exhibits the most excellent hydrogen storage performance, with the highest hydrogen adsorption / desorption amount, reaching 6.98 wt%. In contrast, although the sample obtained in Comparative Example 2 has the highest specific surface area, its hydrogen adsorption / desorption amount is the lowest, only 0.39 wt%. This result indicates that the Zr - Pb - MOF without pyrolysis and the composite material prepared by direct ball milling of MgH 2 do not have the ability to store hydrogen. At the same time, by comparing the test results of the sample obtained in Example 3 with those of the sample obtained in Comparative Example 1, it can be found that the increase in the doping content of Pb(NO 3 ) 2 can improve the specific surface area and hydrogen storage capacity of the nano - composite hydrogen storage material. In addition, from Figure 1 and Figure 2 , it can be known that both Zr - Pb - MOF and Pb@ZrO 2 -C have relatively clear spherical granular shapes, and the elements Pb, Zr, C, and O are evenly distributed in the spherical particles. However, Pb@ZrO 2 -C has nano - spherical particles with smaller sizes and more uniform forming. It has uniformly dispersed metal nodes at the atomic scale, which can provide abundant anchoring sites for MgH 2 . Moreover, the amorphous carbon framework and porous structure after pyrolysis are relatively stable, which is conducive to gas diffusion and electron transfer during the hydrogen atom adsorption / desorption process, thus significantly improving the hydrogen storage performance of the material.

[0066] Although the present invention has been specifically shown and described in combination with preferred embodiments, those skilled in the art should understand that various changes made to the present invention in form and detail without departing from the spirit and scope of the present invention defined by the appended claims all fall within the protection scope of the present invention.

Claims

1. A method for preparing a MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material, characterized in that: The following steps are involved: Step S1: Synthesis of Pb-doped Zr-Pb-MOF using UIO-66 template method; Weigh ZrCl4 and Pb(NO3)2, add them into N,N-dimethylformamide, and stir to obtain solution A; dissolve terephthalic acid in solution A, and perform ultrasonic treatment after mixing to obtain solution B; Solution B was transferred to a separator funnel, and dripped into glacial acetic acid, and solution C was obtained after continuous stirring; solution C was transferred to a hydrothermal kettle, and the product was washed with DMF and ethanol after heating, and the product was vacuum dried overnight to obtain Zr-Pb-MOF; Step S2: preparation of bimetallic nanoparticles; The Zr-Pb-MOF prepared in step S1 is placed in a quartz boat and pyrolyzed under a N2 atmosphere to obtain Pb@ZrO2-C nanoparticles; Step S3: Preparation of MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material; MgH2 and Pb@ZrO2-C prepared in step S2 were weighed, and anhydrous ethanol was added to perform ball milling. The ball-milled mixture was vacuum dried overnight to finally obtain a uniform MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material.

2. The method for preparing the MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material according to claim 1, characterized in that: The specific process of step S1 is as follows: Weigh ZrCl4 and Pb(NO3)2, add to 20-25 mL N,N-dimethylformamide, stir for 15-20 min, and obtain solution A; 1-1.2 mmol of terephthalic acid was dissolved in solution A, mixed and subjected to ultrasonic treatment for 30 min to obtain solution B; Solution B was transferred to a separator funnel and dripped into 2.0-2.4 mL of glacial acetic acid at a rate of 2-3 drops per second, and stirring was continued for 30 minutes to obtain solution C; solution C was transferred to a hydrothermal autoclave, heated at 120-140°C for 20-24 hours, the product was washed with DMF and ethanol, and vacuum dried at 60-70°C overnight to obtain Zr-Pb-MOF.

3. The method for preparing the MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material according to claim 2, characterized in that: In the step S1, the molar ratio of ZrCl4 to Pb(NO3)2 is 1:1-1:1.

4.

4. The method for preparing the MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material according to claim 1, characterized in that: The specific process of step S2 is as follows: The Zr-Pb-MOF prepared in step S1 was placed in a quartz boat, heated to 600-800°C at a heating and cooling rate of 1-5°C / min in a N2 atmosphere, and pyrolyzed for 3h to obtain Pb@ZrO2-C nanoparticles.

5. The method for preparing the MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material according to claim 1, characterized in that: The specific process of step S3 is as follows: Weigh MgH2 and Pb@ZrO2-C prepared in step S2, add anhydrous ethanol, and ball-mill for 30 minutes. The ball-milled mixture is vacuum-dried at 60-70°C overnight to finally obtain a uniform MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material.

6. The method for preparing the MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material according to claim 5, characterized in that: In the step S3, the amount ratio of MgH2 to Pb@ZrO2-C is 10:1-15:

1.

7. A method for preparing the MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material according to any one of claims 1-6 to obtain the MgH2-Pb@ZrO2-C nanocomposite hydrogen storage material.

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