A graphene-supported Ni-MOF hydrogen storage catalyst, preparation method and application thereof
Through graphene-supported Ni-MOF catalyst, the thermal stability and kinetic problems of MgH2 compounds in hydrogen storage applications are solved, the thermal stability and catalytic activity of the catalyst are improved, and more efficient hydrogen storage performance is achieved.
Patent Information
- Application Number
- CN202211532763.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-01
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2042-12-01
AI Technical Summary
MgH2 compounds are limited by high thermal stability and slow kinetics in hydrogen storage applications, and poor thermal stability and dense accumulation of metal-organic framework materials (MOFs) catalysts lead to reduced catalytic activity.
Using graphene-supported Ni-MOF catalyst, the graphene-supported Ni-MOF catalyst is formed by grafting aromatic carboxylic acid derivative functional groups on the surface of graphene oxide and using carboxyl-containing bridge ligands in hydrothermal reactions to increase its heat. Stability and catalytic activity.
The hydrogen storage kinetics and catalytic activity of MgH2 hydrogen storage materials are improved, the thermal stability and catalytic site distribution of the catalyst are enhanced, and the reaction performance of the catalyst is improved.
Smart Images
Figure CN116174041B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of hydrogen storage catalysts, and specifically relates to a graphene-supported Ni-MOF hydrogen storage catalyst, a preparation method and application thereof. Background Art
[0002] As energy crisis and environmental pollution become increasingly prominent, people are more and more in need of clean and renewable energy. Hydrogen storage is the core step to realize hydrogen energy application. MgH2 compounds have become promising candidate materials for hydrogen storage due to their high hydrogen storage capacity, low price and excellent reversibility. However, their high thermal stability and slow kinetics limit their practical application.
[0003] Composite catalysts are one of the most effective methods to improve the hydrogen storage performance of MgH2. Metal organic framework materials (MOFs) have a three-dimensional pore structure, generally with metal ions as connection points, and organic ligands as support to form a three-dimensional extension of space. The uniform distribution of metal atoms at the atomic scale makes MOFs a promising catalyst. However, there are few reports on MOFs as hydrogen storage catalysts. This is because the poor thermal stability of MOFs will cause decomposition when heated, and the released gas will contaminate hydrogen and poison MgH2. In addition, the dense stacking of MOFs will reduce the utilization rate of its catalytic sites and weaken the catalytic activity of the catalyst. Therefore, the present invention proposes a graphene-loaded Ni-MOF hydrogen storage catalyst, its preparation method and application. Summary of the invention
[0004] The object of the present invention is to provide a graphene-supported Ni-MOF hydrogen storage catalyst, a preparation method and application thereof, so as to solve or at least alleviate one or more of the above-mentioned problems and other problems existing in the prior art.
[0005] To achieve the above object, the present invention provides the following technical solutions:
[0006] A method for preparing a graphene-supported Ni-MOF hydrogen storage catalyst comprises the following steps:
[0007] S1. Weigh nickel nitrate hexahydrate and graphene oxide respectively, dissolve them in dimethylformamide, and stir them at room temperature to allow them to undergo a uniform mixing reaction to obtain a mixed solution A;
[0008] S2, weigh terephthalic acid, add it to the solution A obtained in S1, stir it thoroughly to dissolve it, and obtain a mixed solution B;
[0009] The mixed solution B obtained in S3 and S2 is placed in a reactor for heating reaction. After the reaction is completed, the solid and liquid are separated, and the solid product is collected, washed and dried to obtain a graphene-supported Ni-MOF hydrogen storage catalyst, named G@Ni-MOF.
[0010] The mass ratio of nickel nitrate hexahydrate, graphene oxide, dimethylformyl and terephthalic acid is 1: 0.05-0.2: 80-120: 0.5-1.5.
[0011] Preferably, the graphene oxide surface described in S1 is grafted with an aromatic carboxylic acid derivative functional group, wherein the structural formula of the aromatic carboxylic acid derivative is as follows:
[0012]
[0013] R1, R2, and R3 are the same or different, and R1, R2, and R3 are independently selected from one of H, CH3, and OCH3.
[0014] After the aromatic carboxylic acid derivative functional groups are grafted onto the surface of graphene oxide, the surface of graphene oxide contains more abundant oxygen-containing functional groups, which can better anchor Ni ions and effectively avoid agglomeration during subsequent hydrothermal reactions; in addition, the strong carboxyl binding leads to high stability, and the presence of benzene rings provides chemical resistance to hydrides.
[0015] Preferably, the reaction temperature in the reactor in step S3 is 150° C. to 200° C., and the reaction time is 10 h to 14 h.
[0016] Preferably, after solid-liquid separation in step S3, the obtained solid product is washed with dimethylformamide and ethanol respectively, and the washing is continued for more than 3 times.
[0017] Preferably, after washing, the solid product in step S3 is placed in a vacuum drying oven for drying at a drying temperature of 75° C. to 85° C. for a drying time of 6 h to 10 h.
[0018] Preferably, the solid-liquid separation method in step S3 adopts at least one of sedimentation, centrifugation and filtration.
[0019] The present invention also provides a graphene-supported Ni-MOF hydrogen storage catalyst prepared by the above-mentioned preparation method.
[0020] The present invention also provides the use of the graphene-supported Ni-MOF hydrogen storage catalyst prepared by the above-mentioned preparation method in a MgH2 composite hydrogen storage material.
[0021] In addition, the present invention also provides a MgH2 composite hydrogen storage material, which is prepared by the following steps:
[0022] S1. By weight: 0.5-3 parts of the graphene-supported Ni-MOF hydrogen storage catalyst prepared by the above method and 6-10 parts of MgH2 are placed in a ball mill, and then ball milling beads are added;
[0023] S2. Ball milling was performed at a speed of 450 rpm for 5 h under a hydrogen pressure of 2 MPa. The material obtained after ball milling was designated as MgH2 composite hydrogen storage material, and was stored in a glove box for later use.
[0024] Optionally, in step S1, the weight ratio of the graphene-supported Ni-MOF hydrogen storage catalyst to the MgH2 is 1:4.
[0025] Optionally, the ball-to-material ratio in step S1 is 40:1.
[0026] Compared with the prior art, the present invention has the following beneficial effects:
[0027] 1. The present invention provides a method for preparing a graphene-supported Ni-MOF hydrogen storage catalyst. First, graphene oxide is mixed with a Ni salt, and then a carboxyl-containing bridging ligand is added to perform a hydrothermal reaction in a reactor. Among them, the surface of graphene oxide contains abundant oxygen-containing functional groups, which can anchor Ni ions and effectively avoid agglomeration during subsequent hydrothermal reactions; at the same time, the introduction of graphene oxide can make the prepared Ni-MOF evenly dispersed on its surface, fully exposing the catalytic sites. During the high-temperature hydrothermal process, graphene oxide will be reduced to graphene, which improves the conductivity of the composite material and accelerates the transmission of electrons. In addition, the strong carboxyl binding leads to high stability, and the presence of benzene rings provides chemical resistance to hydrides. The preparation method of a graphene-supported Ni-MOF hydrogen storage catalyst proposed by the present invention is simple, and the reaction conditions are mild. It is expected to be applied to other hydrogen storage systems. The introduction of graphene can effectively improve the catalytic activity of the Ni-MOF catalyst. At the same time, the prepared composite catalyst has good thermal stability and can improve the hydrogen storage kinetics of the MgH2 hydrogen storage material.
[0028] 2. Graphene-loaded Ni-MOF hydrogen storage catalyst has good thermal stability and catalytic site distribution, which improves the hydrogen storage capacity of MgH2 hydrogen storage material and improves its reaction kinetics. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 This is a scanning electron microscope image of the graphene-supported Ni-MOF hydrogen storage catalyst of the present invention;
[0030] Figure 2 DSC curves of hydrogen storage composite materials prepared in different embodiments of the present invention;
[0031] Figure 3 A comparison diagram of the activation energy of hydrogen release of the hydrogen storage composite materials prepared in different embodiments of the present invention;
[0032] Figure 4 It is a hydrogen release curve diagram of the graphene-supported Ni-MOF hydrogen storage catalyst of the present invention at different temperatures. DETAILED DESCRIPTION
[0033] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.
[0034] Example 1
[0035] A method for preparing a graphene-supported Ni-MOF hydrogen storage catalyst, the specific steps are as follows:
[0036] Weigh 0.5g nickel nitrate hexahydrate and 0.025g graphene oxide and dissolve them in 40mL dimethylformamide, and stir at room temperature to make them uniformly mixed and react. Add 0.25g terephthalic acid to the mixed solution and stir to dissolve it. Place the obtained mixed solution in a 100mL reactor and react at 150℃ for 10h. Collect the product by sedimentation, centrifugation and filtration, wash it with dimethylformamide and ethanol three times respectively, and dry it in a vacuum oven at 75℃ for 6h. The obtained product is graphene-supported Ni-MOF (G@Ni-MOF).
[0037] Example 2
[0038] A method for preparing a graphene-supported Ni-MOF hydrogen storage catalyst, the specific steps are as follows:
[0039] Weigh 0.5g nickel nitrate hexahydrate and 0.05g graphene oxide and dissolve them in 50mL dimethylformamide, and stir at room temperature to make them uniformly mixed and react. Add 0.4g terephthalic acid to the mixed solution and stir to dissolve it. The obtained mixed solution is placed in a 100mL reactor and reacted at 180℃ for 12h. The product is collected by sedimentation, centrifugation and filtration, washed with dimethylformamide and ethanol 5 times respectively, and dried in a vacuum oven at 80℃ for 8h. The obtained product is graphene-loaded Ni-MOF (G@Ni-MOF).
[0040] Example 3
[0041] A method for preparing a graphene-supported Ni-MOF hydrogen storage catalyst, the specific steps are as follows:
[0042] Weigh 0.5g nickel nitrate hexahydrate and 0.1g graphene oxide and dissolve them in 60mL dimethylformamide, and stir at room temperature to make them uniformly mixed and react. Add 0.75g terephthalic acid to the mixed solution and stir to dissolve it. Place the obtained mixed solution in a 100mL reactor and react at 200℃ for 14h. Collect the product by sedimentation, centrifugation and filtration, wash it with dimethylformamide and ethanol for 6 times respectively, and dry it in a vacuum drying oven at 85℃ for 10h. The obtained product is graphene-supported Ni-MOF (G@Ni-MOF).
[0043] Among Examples 1 to 3, the yield of G@Ni-MOF prepared by the method of Example 2 is the highest and the structure is more stable and uniform, so Example 2 is the best ratio. The structure of G@Ni-MOF prepared in Example 2 was photographed with a scanning electron microscope, and the scanning electron microscope photo is as follows: Figure 1 shown.
[0044] Example 4
[0045] On the basis of Example 2, in this example, aromatic carboxylic acid derivative functional groups are grafted onto the surface of graphene oxide.
[0046] After the aromatic carboxylic acid derivative functional groups are grafted onto the surface of graphene oxide, the surface of graphene oxide contains more abundant oxygen-containing functional groups, which can better anchor Ni ions and effectively avoid agglomeration during subsequent hydrothermal reactions; in addition, the strong carboxyl binding leads to high stability, and the presence of benzene rings provides chemical resistance to hydrides.
[0047] Example 5
[0048] On the basis of Example 2, in this example, in the step of preparing graphene-supported Ni-MOF, graphene oxide is not added, and a Ni-MOF catalyst can be prepared.
[0049] Example 6
[0050] 0.8 g of MgH2 and 0.2 g of the sample prepared in Example 2 were weighed and placed in a ball mill, and then 40 g of ball milling beads were added. The mixture was ball milled at a speed of 450 rpm for 5 h under a hydrogen pressure of 2 MPa to obtain MgH2+G@Ni-MOF.
[0051] Example 7
[0052] 0.8 g of MgH2 and 0.2 g of the sample prepared in Example 5 were weighed and placed in a ball mill, and then 40 g of ball milling beads were added. The mixture was ball milled at a speed of 450 rpm for 5 h under a hydrogen pressure of 2 MPa to obtain MgH2+Ni-MOF.
[0053] Research on hydrogen storage performance:
[0054] At different heating rates, the hydrogen release performance of the MgH2+G@Ni-MOF, MgH2+Ni-MOF composite materials and pure MgH2 prepared in the above examples was studied by differential scanning calorimetry, and the obtained data was fitted using the Kissinger method. The fitting results are shown in Figure 2 , Figure 3As shown in Figure 2, the MgH2 of the composite G@Ni-MOF catalyst has the lowest activation energy for hydrogen desorption. In addition, the hydrogen desorption performance of the G@Ni-MOF composite material was tested at different temperatures. The test results are shown in Figure 2. Figure 4 shown.
[0055] It can be seen that the introduction of graphene can effectively improve the catalytic activity of Ni-MOF catalysts. At the same time, the prepared composite catalyst has good thermal stability and can improve the hydrogen storage kinetics of MgH2 hydrogen storage materials.
[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.
Claims
1. Application of a graphene-supported Ni-MOF hydrogen storage catalyst in a MgH2 composite hydrogen storage material, wherein the preparation method of the graphene-supported Ni-MOF hydrogen storage catalyst is as follows: S1. Weigh nickel nitrate hexahydrate and graphene oxide respectively, dissolve them in dimethylformamide, and stir them at room temperature to allow them to undergo a uniform mixing reaction to obtain a mixed solution A; S2, weigh terephthalic acid, add it to the solution A obtained in S1, stir it thoroughly to dissolve it, and obtain a mixed solution B; The mixed B solution obtained in S3 and S2 is placed in a reactor for heating reaction. After the reaction is completed, the solid and liquid are separated, and the solid product is collected, washed, and dried to obtain a graphene-supported Ni-MOF hydrogen storage catalyst, named G@Ni-MOF. in, The mass ratio of nickel nitrate hexahydrate, graphene oxide, dimethylformyl and terephthalic acid is 1: 0.05-0.2: 80-120: 0.5-1.
5.
2. The use according to claim 1, characterized in that: The graphene oxide described in S1 is grafted with an aromatic carboxylic acid derivative functional group on its surface, wherein the aromatic carboxylic acid derivative has the following structural formula: R1, R2, and R3 are the same or different, and R1, R2, and R3 are independently selected from one of H, CH3, and OCH3.
3. The use according to claim 2, characterized in that: In step S3, the reaction temperature in the reactor is 150° C. to 200° C., and the reaction time is 10 h to 14 h.
4. The use according to claim 3, characterized in that: After solid-liquid separation in step S3, the obtained solid product is washed with dimethylformamide and ethanol respectively, and the washing is continued for more than 3 times.
5. The use according to claim 4, characterized in that: In step S3, after washing, the solid product is placed in a vacuum drying oven for drying at a temperature of 75° C. to 85° C. for a drying time of 6 h to 10 h.
6. The use according to claim 5, characterized in that: The solid-liquid separation method in step S3 adopts at least one of sedimentation, centrifugation and filtration.