Copper-based MOF derived carbon-MgH2 composite solid hydrogen storage material and preparation method thereof

Abstract

The invention discloses a copper-based MOF derived carbon-MgH2 composite solid hydrogen storage material and a preparation method thereof.The preparation method comprises the steps that 1, metal inorganic salt is dissolved in deionized water, stirring is conducted till reactants are dissolved, and a solution a is obtained; 2, trimesic acid is dissolved in a solution composed of N, N-dimethylformamide and methanol according to the volume ratio of 1: 1, ultrasonic treatment is conducted, and a solution b is obtained; 3, mixing and stirring the solution a and the solution b to obtain a mixed solution; step 4, adding the mixed solution into a reaction kettle for reaction, and after the reaction, performing furnace cooling overnight to room temperature; 5, a first product obtained after the reaction is washed with N, N-dimethylformamide and methyl alcohol for multiple times, and drying is conducted to obtain a Cu-based MOFs material; and 6, the dried Cu-based MOF material and MgH2 are mixed and subjected to ball milling, and the MOF catalyzed magnesium-based composite hydrogen storage material is obtained. The synthesis is simple, the reaction condition is mild, and the introduction of the copper-based MOF effectively improves the hydrogen absorption / desorption behavior of the MgH2 hydrogen storage material.

Description

Technical Field

[0001] The present invention relates to the technical field of solid hydrogen storage materials, and in particular to a copper-based MOF-derived carbon-MgH 2 Composite solid-state hydrogen storage material and preparation method thereof. Background Art

[0002] Hydrogen has a high combustion calorific value and zero pollution from combustion products, making it the most ideal clean energy. However, due to the storage and safety issues of hydrogen, the large-scale application of hydrogen energy is greatly limited. Solid-state hydrogen storage methods are expected to break this technical barrier. Magnesium has a high hydrogen storage capacity (7.6wt%) and a high volumetric hydrogen storage density (110kg H 2 / m 3 ), high cycle stability and reversibility, low toxicity, low cost and other advantages stand out among many solid-state hydrogen storage materials, but its stable hydrogen storage thermodynamics, slow hydrogen release kinetics, and easy oxidation in the air have hindered the development of its practical application. Therefore, the development of long-life, high-capacity magnesium-based hydrogen storage materials has important scientific and practical significance for the development and application of hydrogen energy.

[0003] Adding catalyst can significantly reduce MgH 2 At present, the added catalysts mainly include transition metals, transition metal oxides, etc. These materials have been proven to be useful for increasing the energy barrier of MgH 2 hydrogen storage performance. Révész et al. used high-energy ball milling to produce MgH 2 The transition metal FeTi was introduced into the nanostructured carbon nanotubes, and the effect of different grinding times (1 h, 3 h, and 10 h) on the H 2 Adsorption performance. The results show that the total amount of hydrogen absorbed by the alloy (3h) reached 6.9wt% in the first 10min, but its performance results were only achieved when the number of cycles was small (https: / / doi.org / 10.3390 / en16031061). Catalysts commonly used for hydrogen storage are prone to agglomeration during continuous, high-speed ball milling, resulting in reduced catalytic site activity and reduced material hydrogen absorption / desorption performance. Therefore, the development of highly active catalysts is of great significance to maintaining the high hydrogen absorption / desorption performance of hydrogen storage materials. Summary of the invention

[0004] In order to overcome the defects of the above prior art, the object of the present invention is to provide a copper-based MOF-derived carbon-MgH 2 Composite solid-state hydrogen storage material and preparation method thereof, the method has simple synthesis, mild reaction conditions, and the introduction of copper-based MOF-derived carbon effectively improves MgH 2The hydrogen absorption / desorption behavior of the hydrogen storage material reduces the hydrogen absorption / desorption temperature, and the preparation method of the magnesium-based solid hydrogen storage material is simple and easy, and can be widely used in most hydrogen storage systems.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A copper-based MOF-derived carbon-MgH 2 Composite solid-state hydrogen storage material, copper-based MOF and MgH 2 Mixing under hydrogen atmosphere to prepare a copper-based MOF-derived carbon-MgH 2 Composite solid hydrogen storage materials;

[0007] By high energy ball milling 2 The copper-based MOF was mixed with Mg in the presence of 2 Composite materials, copper-based MOF-derived carbon-MgH2O obtained during hydrogen absorption / desorption at 250-350°C 2 Composite materials;

[0008] At high temperatures, the copper-based MOF structure collapses and is decomposed into copper-based MOF-derived carbon, which is distributed in the MgH 2 The surface has an average particle size of 1-1.4 μm. The SEM test results show that during the ball milling process, there are many holes and cracks on the surface of the solid hydrogen storage material. The holes and cracks provide channels for the transmission and diffusion of hydrogen, which significantly improves the MgH 2 dynamic performance.

[0009] The present invention uses a typical copper-based MOF: [Cu 3 (BTC) 2 ] n (HKUST-1,H 3 BTC = pyromellitic acid), which has the advantages of large specific surface area, high porosity, low price, good temperature stability, and relatively high hydrogen storage capacity (0.47 wt.% at 303 K and 35 bar). Therefore, it was selected as the precursor of copper-based MOF-derived carbon for loading MgH 2 Materials, preparation of a copper-based MOF-derived carbon-MgH 2 Composite solid-state hydrogen storage materials.

[0010] A copper-based MOF-derived carbon-MgH 2 A method for preparing a composite solid hydrogen storage material comprises the following steps:

[0011] Step 1: dissolving an inorganic salt of copper in deionized water, and stirring until the reactant is dissolved to obtain a solution a;

[0012] Step 2: dissolving trimesic acid in a solution consisting of N,N-dimethylformamide and methanol in a volume ratio of 1:1, and subjecting the solution to ultrasonic treatment to obtain a solution b;

[0013] Step 3: Mix solution a and solution b and stir to obtain a mixed solution;

[0014] Step 4: adding the mixed solution into a reactor for reaction, and after the reaction is completed, cooling to room temperature to obtain a copper-based MOF material;

[0015] Step 5: The copper-based MOF material after the reaction is washed several times with N,N-dimethylformamide and methanol respectively, and then dried to remove the copper salt and ligand on the surface of the material to obtain a Cu-based MOF material;

[0016] Step 6: Dry the obtained Cu-based MOF material and MgH 2 Mixed ball milling to obtain copper-based MOF-derived carbon-MgH 2 Composite solid-state hydrogen storage materials.

[0017] In the step 1, the inorganic salt of copper is copper (II) nitrate trihydrate;

[0018] Preparation of the copper-based MOF-derived carbon-catalyzed MgH 2 The steps for preparing hydrogen storage materials must be carried out in a glove box.

[0019] In the step 2, the copper inorganic salt, trimesic acid, and N,N-dimethylformamide have a mass ratio of 1:15:30 to 15:1:30.

[0020] In the step 3, the mixture is mixed and stirred for 15 to 60 minutes at a rotation speed of 400 to 750 rpm, and the ultrasonic treatment is performed for 15 to 60 minutes.

[0021] In the step 4, the reactor is sealed and heated to 80-180° C. and kept warm for 12-18 hours.

[0022] In step 6, MgH 2 The mass ratio of Cu-based MOF to MgH 2 The ball milling is carried out in a hydrogen atmosphere with a hydrogen pressure of 0.7 to 1 MPa and a ball-to-material ratio of 20:1 to 40:1; the ball milling time is 2 to 6 hours, and the ball milling speed is controlled at 400 to 1200 rpm to obtain a MOF-catalyzed magnesium-based composite hydrogen storage material.

[0023] The MOF-catalyzed magnesium-based composite hydrogen storage material is used for hydrogen storage.

[0024] Beneficial effects of the present invention:

[0025] In step 6, the copper-based MOF material is compounded with Mg in a glove box, and a MOF-Mg composite material with uniformly dispersed copper metal atoms is prepared by adjusting the ratio of the copper-based MOF material to Mg, the rotation speed and time of high-energy ball milling. The copper-based MOF material serves as both a catalyst and a protective agent. Its introduction can effectively reduce the hydrogen absorption / desorption temperature, improve the kinetic performance, and overcome the problem that Mg is easily oxidized when exposed to air.

[0026] By adding copper-based MOF-derived carbon and MgH without added catalyst 2 The comparison of the hydrogen storage performance of the materials showed that the addition of copper-based MOF-derived carbon to MgH 2 Under the conditions of hydrogen absorption pressure of 30 bar, hydrogen absorption temperature of 250℃, 300℃, 350℃, and hydrogen absorption time of 60 min, the hydrogen absorption concentrations were 6.01wt%, 6.13wt%, and 6.43wt%, respectively; under the conditions of hydrogen desorption temperature of 350℃ and hydrogen desorption time of 60 min, the hydrogen desorption concentration was 5.4wt%. Compared with the original MgH 2 The hydrogen absorption and desorption performance under the same conditions confirmed the copper-based MOF-derived carbon to catalyze MgH 2 Kinetic and thermodynamic effects have a significant impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The copper-based MOF-derived carbon-catalyzed MgH 2 Hydrogen storage materials and pure MgH 2 XRD pattern with PDF standard card.

[0028] Figure 2 This is the SEM and particle size distribution diagram of the copper-based MOF-derived carbon-catalyzed MgH2 hydrogen storage material of the present invention.

[0029] Figure 3 The copper-based MOF-derived carbon-catalyzed MgH 2 Hydrogen storage materials and pure MgH 2 Hydrogen absorption curve at 350℃.

[0030] Figure 4 The copper-based MOF-derived carbon-catalyzed MgH 2 Hydrogen storage materials and pure MgH 2 Hydrogen desorption curve at 350°C.

[0031] Figure 5 The copper-based MOF-derived carbon-catalyzed MgH 2 Hydrogen absorption curves of hydrogen storage materials at 250℃, 300℃ and 350℃ respectively.

[0032] Figure 6 The copper-based MOF-derived carbon-catalyzed MgH 2 TPD curves of hydrogen storage materials.

[0033] Figure 7 The copper-based MOF-catalyzed MgH 2 Adsorption isotherm of hydrogen storage material at 350 °C.

[0034] Figure 8 The copper-based MOF-catalyzed MgH 2 Desorption isotherms of hydrogen storage materials at 350 °C.

[0035] Fig. 9 Schematic diagram of the preparation route and hydrogen absorption / desorption performance of the magnesium-based composite material of the present invention. DETAILED DESCRIPTION

[0036] The following is further described in conjunction with the embodiments;

[0037] like Figure 1-Figure 9 As shown, the present invention discloses a copper-based MOF-derived carbon-MgH 2 Composite solid hydrogen storage material and preparation method thereof;

[0038] Embodiment 1:

[0039] Preparation of Cu-MOF materials

[0040] Dissolve copper nitrate (0.017 mol) in 33 mL of deionized water. At the same time, dissolve 1,3,5-tricarboxylic acid (0.001 mol) in 67 mL of a solution of N,N-dimethylformamide (DMF) and methanol in a volume ratio of 1:1 and ultrasonicate for 15 minutes. Mix, stir, and ultrasonicate for 60 minutes. After that, transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and react in an oven at 120 ° C for 16 hours. After the reaction is completed, cool to room temperature, separate the product by suction filtration, wash it several times with DMF and methanol, and then dry it at room temperature.

[0041] Preparation of MgH by high energy ball milling 2 -Cu-MOF derived carbon composite hydrogen storage materials

[0042] Weigh 0.9 g MgH 2 , and MgH 2 The mass ratio of Cu-based MOF to MgH 2 The ball milling was carried out in a hydrogen atmosphere with a hydrogen pressure of 0.7-1 MPa, the ball-to-material ratio was set to 40:1 and the ball milling time was 4 h. The ball milling speed was controlled at 800 rpm to obtain MgH 2 -Cu-MOF derived carbon composite hydrogen storage materials.

[0043] The weighing and adding of the above work were all carried out in a glove box (oxygen content ≤ 0.1 ppm, water content ≤ 0.1 ppm).

[0044] Embodiment 2:

[0045] Preparation of Cu-MOF materials

[0046] Dissolve copper nitrate (0.015 mol) in 30 mL of deionized water. At the same time, dissolve 1,3,5-tricarboxylic acid (0.001 mol) in 70 mL of a solution of N,N-dimethylformamide (DMF) and methanol in a volume ratio of 1:1, and ultrasonicate for 30 minutes. Mix, stir, and ultrasonicate for 30 minutes. After that, transfer the mixture to a small glass bottle and react in an oven at 100 ° C for 14 hours. After the reaction is completed, cool to room temperature, separate the product by suction filtration, wash it several times with DMF and methanol, and then dry it at room temperature.

[0047] Preparation of MgH by high energy ball milling 2 -Cu-MOF derived carbon composite hydrogen storage materials

[0048] Weigh 0.8 g MgH 2 , and MgH 2 The mass ratio of Cu-based MOF to MgH 2 The ball milling was carried out in a hydrogen atmosphere with a hydrogen pressure of 0.7-1 MPa, the ball-to-material ratio was set to 20:1 and the ball milling time was 6 h. The ball milling speed was controlled at 600 rpm to obtain MgH 2 -Cu-MOF derived carbon composite hydrogen storage materials.

[0049] The weighing and adding of the above work were all carried out in a glove box (oxygen content ≤ 0.1 ppm, water content ≤ 0.1 ppm).

[0050] Embodiment 3:

[0051] Preparation of Cu-MOF materials

[0052] Dissolve copper nitrate (0.01 mol) in 20 mL of deionized water. At the same time, dissolve 1,3,5-tricarboxylic acid (0.001 mol) in 80 mL of a solution of N,N-dimethylformamide (DMF) and methanol in a volume ratio of 1:1 and ultrasonicate for 45 minutes. Mix, stir, and ultrasonicate for 60 minutes. After that, transfer the mixture to a stainless steel autoclave lined with polytetrafluoroethylene and react in an oven at 150°C for 15 hours. After the reaction is completed, cool to room temperature, separate the product by suction filtration, wash it several times with DMF and methanol, and then dry it at room temperature.

[0053] Preparation of MgH by high energy ball milling 2-Cu-MOF derived carbon composite hydrogen storage materials

[0054] Weigh 0.7 g MgH 2 , and MgH 2 The mass ratio of Cu-based MOF to MgH 2 The ball milling was carried out in a hydrogen atmosphere with a hydrogen pressure of 0.7-1 MPa, the ball-to-material ratio was set to 30:1 and the ball milling time was 2 h. The ball milling speed was controlled at 1000 rpm to obtain MgH 2 -Cu-MOF derived carbon composite hydrogen storage materials.

[0055] The weighing and adding of the above work were all carried out in a glove box (oxygen content ≤ 0.1 ppm, water content ≤ 0.1 ppm).

[0056] Characterization:

[0057] X-ray powder diffraction analysis shows that MgH 2 existence.

[0058] application:

[0059] MgH 2 -Test of hydrogen absorption and desorption performance of Cu-MOF derived carbon composite hydrogen storage materials at different temperatures:

[0060] The automatic test program of hydrogen absorption and desorption behavior of Guoyi Quantum's high temperature and high pressure adsorption instrument (H-Sorb2600) was used to characterize the hydrogen absorption / desorption behavior and thermodynamic properties of the composite hydrogen storage material at different temperatures. Figure 2 , Figure 3 and Figure 4 As shown. Figure 2 and Figure 3 It can be seen that the hydrogen absorption / desorption capacity of the magnesium-based material with and without copper-based MOF at 350°C is 6.4wt% and 5.4wt%, respectively. Figure 4 By testing the hydrogen absorption performance of the composite hydrogen storage material at different temperatures, it can be found that the hydrogen absorption rate can reach 6.01wt% at 250℃ and 30min, and can reach 6.11wt% within 7min at 300℃. In summary, the composite material exhibits a good hydrogen absorption reaction rate. 2 -The hydrogen absorption kinetics of Cu-MOF-derived carbon composite hydrogen storage materials are significantly improved.

[0061] Hydrogen desorption test and PCT isotherm performance characterization of composite hydrogen storage materials

[0062] The dehydrogenation test was performed using the TPD program. The dehydrogenation curve was obtained by setting the program temperature to rise by 1°C / min. Figure 5 As shown. Figure 5 MgH2 -Cu-MOF derived carbon composite hydrogen storage material has a significantly lower dehydrogenation temperature than pure magnesium hydride, from 420℃ of pure magnesium hydride to 325℃. Figure 6 and Figure 7 It can be seen that MgH 2 -Cu-MOF derived carbon composite hydrogen storage material has a hydrogen absorption platform pressure drop of 5 bar and 3 bar compared with pure magnesium hydride. And the curve can be divided into early tilt, mid-term platform and late tilt, which represent MgH 2 - Physical adsorption of hydrogen by Cu-MOF-derived carbon composite hydrogen storage, Mg to MgH 2 The transformation of MgH 2 -Cu-MOF derived carbon physical adsorption process. This shows that the composite material has excellent reversible hydrogen absorption and desorption properties at 350 ° C ( Figure 8 ).

Claims

1. A copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material, characterized in that: A copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material was prepared by mixing copper-based MOF and MgH2 in a hydrogen atmosphere through high-energy ball milling. The copper-based MOF-MgH2 composite material was prepared by mixing the copper-based MOF with Mg in the presence of H2 by high-energy ball milling, and the copper-based MOF-derived carbon-MgH2 composite material was obtained during the hydrogen absorption / desorption process at 250-350°C; Under high temperature, the copper-based MOF structure collapses and is decomposed into copper-based MOF-derived carbon, which is distributed on the surface of MgH2 with an average particle size of 1-1.4μm; there are many pores and cracks on the surface of the solid hydrogen storage material, which provide channels for the transmission and diffusion of hydrogen.

2. The method for preparing a copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material according to claim 1, characterized in that: The steps include: Step 1: dissolving an inorganic salt of copper in deionized water, and stirring until the reactant is dissolved to obtain a solution a; Step 2: dissolving trimesic acid in a solution consisting of N,N-dimethylformamide and methanol in a volume ratio of 1:1, and subjecting the solution to ultrasonic treatment to obtain a solution b; Step 3: Mix solution a and solution b and stir to obtain a mixed solution; Step 4: adding the mixed solution into a reactor for reaction, and after the reaction is completed, cooling to room temperature to obtain a copper-based MOF material; Step 5: The copper-based MOF material after the reaction is washed several times with N,N-dimethylformamide and methanol respectively, and then dried to remove the copper salt and ligand on the surface of the material to obtain a Cu-based MOF material; Step 6: The dried Cu-based MOF material is mixed with MgH2 and ball-milled to obtain a copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material.

3. The method for preparing a copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material according to claim 2, characterized in that: In the step 1, the inorganic salt of copper is copper (II) nitrate trihydrate; The step of preparing the copper-based MOF-derived carbon-catalyzed MgH2 hydrogen storage material needs to be carried out in a glove box.

4. The method for preparing a copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material according to claim 2, characterized in that: In the step 2, the copper inorganic salt, trimesic acid, and N,N-dimethylformamide have a mass ratio of 1:15:30 to 15:1:

30.

5. The method for preparing a copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material according to claim 2, characterized in that: In the step 3, the mixture is mixed and stirred for 15 to 60 minutes at a rotation speed of 400 to 750 rpm, and the ultrasonic treatment is performed for 15 to 60 minutes.

6. The method for preparing a copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material according to claim 2, characterized in that: In the step 4, the reactor is sealed and heated to 80-180° C. and kept warm for 12-18 hours.

7. The method for preparing a copper-based MOF-derived carbon-MgH2 composite solid hydrogen storage material according to claim 2, characterized in that: In the step 6, the mass ratio of MgH2 to Cu-based MOF is 9:1-7:3; the ball milling of Cu-based MOF and MgH2 is carried out in a hydrogen atmosphere, and the hydrogen pressure is 0.7-1 MPa, and the ball-to-material ratio is 20:1-40:1; the ball milling time is 2-6 hours, and the ball milling speed is controlled at 400-1200 rpm, so as to obtain a MOF-catalyzed magnesium-based composite hydrogen storage material.

8. The MOF-catalyzed magnesium-based composite hydrogen storage material according to any one of claims 1 to 7, characterized in that: The MOF-catalyzed magnesium-based composite hydrogen storage material is used for hydrogen storage.

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