Catalyst-doped magnesium-based hydrogen storage material and method for preparing the same

Abstract

The application discloses a kind of catalyst doped magnesium-based hydrogen storage materials and preparation method thereof, belong to hydrogen storage material and its preparation technical field.The application improves the hydrogen absorption and desorption kinetics of existing magnesium-based hydrogen storage material, reduces its hydrogen desorption activation energy, and solves the problem of poor cycle stability.The application uses Cu (NO3) 2·H2O and H3BTC raw materials to prepare catalyst with porous structure, and dopes it in magnesium-based hydrogen storage material by ball milling technology, utilizes the porous structure of catalyst to avoid the agglomeration of active material during hydrogen absorption and desorption process, and the introduced metal can be used as catalytic site to improve the hydrogen absorption and desorption kinetics of magnesium-based hydrogen storage material Mg 85 Ni 10 La 4.5 Y 0.5 Desorption activation energy.

Description

Technical Field

[0001] This invention relates to a catalyst-doped magnesium-based hydrogen storage material and its preparation method, belonging to the technical field of hydrogen storage materials and their preparation. Background Technology

[0002] Considering factors such as volumetric hydrogen storage density, energy consumption, and safety, metal-based hydrogen storage materials are currently recognized as one of the best methods for hydrogen storage. Meanwhile, magnesium-based hydrogen storage materials possess advantages such as low cost, excellent reversibility, high hydrogen storage capacity, and abundant elemental reserves, making them one of the most promising and worthy of research. However, magnesium-based hydrogen storage materials have relatively high hydrogen absorption and desorption temperatures (300-400℃) and poor kinetic and thermodynamic properties, making it difficult to directly meet the requirements of practical applications.

[0003] Currently, solid-state ball milling is a relatively simple and practical method for improving the performance of magnesium-based alloys by adding catalysts. For example, Chemical Engineering Journal 458(2023)141337 points out that by doping NiFe@CNT, MgH2-NiFe@CNT absorbs 4.06 wt.% H2 at 373 K, while pure MgH2 can only absorb 0.82 wt.% H2 at 423 K. M. Iamail improved the hydrogen release performance of MgH2 with CuFe2O4; at 320 °C, CuFe2O4-doped MgH2 released 5.3 wt.% H2 within 10 minutes, while under the same conditions, pure MgH2 could only release 1 wt.% H2 (see International Journal of Hydrogen Energy 44(2019)318-324). However, during hydrogen absorption and desorption, magnesium-based hydrogen storage materials are prone to agglomeration, reducing the number of active sites and causing performance degradation, resulting in poor cycle stability. Summary of the Invention

[0004] This invention addresses the shortcomings of existing magnesium-based hydrogen storage materials by providing a catalyst-doped magnesium-based hydrogen storage material and its preparation method.

[0005] The technical solution of the present invention:

[0006] One objective of this invention is to provide a method for preparing a catalyst-doped magnesium-based hydrogen storage material, the method comprising the following steps:

[0007] Step 1: Dissolve Cu(NO3)2·H2O in deionized water to obtain solution A, and dissolve H3BTC in anhydrous ethanol to obtain solution B. Mix solution A and solution B and transfer them to an autoclave for hydrothermal reaction. After the reaction is completed, centrifuge, collect the solid, wash and vacuum dry it, and then calcine it under inert gas protection to obtain the catalyst.

[0008] Step two, the catalyst obtained in step one and Mg 85 Ni 10 La 4.5 Y 0.5 After mixing, the mixture is ball-milled to obtain a catalyst-doped magnesium-based hydrogen storage material.

[0009] Further specified, the mass ratio of Cu(NO3)2·H2O to H3BTC is 1:(2-2.5).

[0010] Further specifying, the mass-to-volume ratio of Cu(NO3)2·H2O to deionized water in solution A is (0.84-1.68) g: 18 mL.

[0011] Furthermore, the mass-to-volume ratio of Cu(NO3)2·H2O to deionized water in solution A is 0.84 g: 18 mL.

[0012] Further specifying, the mass-to-volume ratio of H3BTC to anhydrous ethanol in solution B is (0.39-0.78) g: 18 mL.

[0013] Furthermore, the mass-to-volume ratio of H3BTC to anhydrous ethanol in solution B is 0.39 g: 18 mL.

[0014] Further, the hydrothermal reaction temperature is (120-140)℃, and the holding time is (12-18)h.

[0015] Furthermore, the hydrothermal reaction temperature is set at 120℃, and the holding time is 12 hours.

[0016] Further specifying, the heating rate of the hydrothermal reaction treatment is 5℃ / min.

[0017] Further specified, a cleaning solution prepared by mixing anhydrous ethanol and water at a volume ratio of 1:1 is used for washing.

[0018] Further specified, the vacuum drying process is performed at a temperature of 80℃ for 12 hours.

[0019] Further specified, the calcination temperature is (350-500)℃, and the holding time is (3-5)h.

[0020] Furthermore, the roasting temperature is set at 400℃ and the holding time is set at 3 hours.

[0021] Further specified, the heating rate of the calcination treatment is 5℃ / min.

[0022] Further specifying, the catalyst and Mg 85 Ni 10 La 4.5 Y0.5 The mass ratio is 1-15 wt.%.

[0023] To further specify, the catalyst and Mg 85 Ni 10 La 4.5 Y 0.5 The mixing takes place in the glove box.

[0024] Further specified, the ball mill speed is (300-400) r / min, the time is (3-5) h, and the ball-to-material ratio is 20:1.

[0025] Further specified, the ball mill speed is 350 r / min, the time is 5 h, and the ball-to-material ratio is 20:1.

[0026] To further specify, the balls used in the ball milling process are steel balls with a diameter of 3-15mm.

[0027] The second objective of this invention is to provide a catalyst-doped magnesium-based hydrogen storage material obtained by the above preparation method, which exhibits good hydrogen desorption performance at lower temperatures.

[0028] Beneficial effects:

[0029] (1) This invention first prepares a catalyst with a special morphology by reacting H3BTC and Cu(NO3)2·3H2O. The porous structure of the catalyst is used to avoid the aggregation of active materials during hydrogen absorption and desorption. At the same time, the introduced metal can serve as a catalytic site to improve the performance of magnesium-based hydrogen storage materials. 85 Ni 10 La 4.5 Y 0.5 The hydrogen absorption and desorption kinetics are analyzed to reduce the activation energy of hydrogen desorption. For magnesium-based hydrogen storage materials doped with catalysts, Mg... 85 Ni 10 La 4.5 Y 0.5 The hydrogen storage performance was characterized, and the results showed that when the catalyst doping amount was 10 wt.%, the hydrogen absorption capacity of the material reached 5.4819 wt.% within 360 s at 260 °C and 5 MPa; and 5.0742 wt.% within 360 s at 220 °C. Simultaneously, the material exhibited good hydrogen release performance, with a hydrogen release capacity of 5.5692 wt.% within 360 s at 300 °C. Furthermore, the material demonstrated good cycle stability; after 10 cycles, the hydrogen absorption capacity remained stable at 98.8%, and the hydrogen release capacity remained stable at 98.1%.

[0030] (2) The catalyst preparation method provided by the present invention is simple, the raw materials are readily available and inexpensive, the application method is simple and easy to operate, and it is more suitable for industrial application. Attached Figure Description

[0031] Figure 1 The Cu@C catalyst prepared in Example 1 and the Mg catalyst doped with the catalyst 85 Ni 10 La 4.5 Y 0.5 XRD patterns of hydrogen storage materials;

[0032] Figure 2 SEM image of the Cu@C catalyst prepared in Example 1;

[0033] Figure 3 The N2 adsorption-desorption curve of the Cu@C catalyst prepared in Example 1 at 77 K is shown.

[0034] Figure 4 The pore size distribution diagram is shown for the Cu@C catalyst prepared in Example 1.

[0035] Figure 5 When the Cu@C catalyst doping amount is 10 wt.%, Mg 85 Ni 10 La 4.5 Y 0.5 Comparison of isothermal hydrogen absorption performance of hydrogen storage materials at 5 MPa and temperatures of 220℃, 240℃ and 260℃.

[0036] Figure 6 When the Cu@C catalyst doping amount is 10 wt.%, Mg 85 Ni 10 La 4.5 Y 0.5 Comparison of isothermal hydrogen desorption performance of hydrogen storage materials at temperatures of 260℃, 280℃ and 300℃;

[0037] Figure 7 When the Cu@C catalyst doping amount is 10 wt.%, Mg 85 Ni 10 La 4.5 Y 0.5 Cycling characteristics of hydrogen storage materials at 300℃;

[0038] Figure 8 For Cu@C catalysts with doping amounts of 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.%, Mg 85 Ni 10 La 4.5 Y 0.5 Comparison of hydrogen absorption performance of hydrogen storage materials at 5 MPa and 220℃ under isothermal conditions. Detailed Implementation

[0039] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0040] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0042] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0043] Example 1

[0044] Step 1: Preparation of Cu@C catalyst

[0045] (1) Dissolve 0.84g Cu(NO3)2·3H2O in 18mL of deionized water to obtain solution A; dissolve 0.39g H3BTC (tribenzoic acid) in 18mL of anhydrous ethanol to obtain solution B. Mix solution A and solution B and stir them evenly with magnetic force to prepare a mixture for later use.

[0046] (2) Transfer all the mixture to a 100mL autoclave lined with polytetrafluoroethylene, then place the autoclave in a blower dryer and heat it to 120℃ at a heating rate of 5℃ / min, and keep it at that temperature for 12h.

[0047] (3) After the reaction is complete, centrifuge and collect the solid. Wash it with a mixture of water and anhydrous ethanol in a volume ratio of 1:1. After washing, dry it in a vacuum drying oven at 80°C for 12 hours to obtain the blue precursor.

[0048] (4) The blue precursor was placed in a muffle furnace and heated to 400°C at a rate of 5°C / min under an argon atmosphere. The temperature was maintained for 3 hours and then cooled to obtain the Cu@C catalyst.

[0049] Step 2: Cu@C catalyst doped with Mg 85 Ni 10 La 4.5Y 0.5 Preparation of hydrogen storage materials

[0050] Weigh 0.1g of Cu@C catalyst and 0.9g of Mg in a glove box. 85 Ni 10 La 4.5 Y 0.5 The sample was placed in a ball mill jar and milled at a speed of 350 r / min for 5 hours to obtain Mg with a doping content of 10 wt.%. 85 Ni 10 La 4.5 Y 0.5 Hydrogen storage materials.

[0051] Example 2

[0052] The difference between this embodiment and Embodiment 1 is as follows: In step two, 0.15g of Cu@C catalyst and 0.85g of Mg are weighed in the glove box. 85 Ni 10 La 4.5 Y 0.5 The sample was placed in a ball mill jar, and the remaining parameter settings and process steps were the same as in Example 1, resulting in Mg with a doping amount of 15 wt.%. 85 Ni 10 La 4.5 Y 0.5 Hydrogen storage materials.

[0053] Example 3

[0054] The difference between this embodiment and Embodiment 1 is as follows: In step two, 0.05g of Cu@C catalyst and 0.95g of Mg are weighed in the glove box. 85 Ni 10 La 4.5 Y 0.5 The sample was placed in a ball mill jar, and the remaining parameter settings and process steps were the same as in Example 1, to obtain Mg with a doping amount of 5 wt.%. 85 Ni 10 La 4.5 Y 0.5 Hydrogen storage materials.

[0055] Comparative Example 1

[0056] The difference between this embodiment and Embodiment 1 is as follows: In step two, 0g of Cu@C catalyst and 1.00g of Mg are weighed in the glove box. 85 Ni 10 La 4.5 Y 0.5 The sample was placed in a ball mill jar, and the remaining parameter settings and process steps were the same as in Example 1, resulting in Mg with a doping amount of 0 wt.%. 85 Ni 10 La4.5 Y 0.5 Hydrogen storage materials.

[0057] Example of effect

[0058] The Cu@C catalyst prepared in Example 1 and Mg with a doping amount of 10 wt.% were compared. 85 Ni 10 La 4.5 Y 0.5 The structure and performance of the hydrogen storage material were characterized, and the specific characterization methods and results are as follows:

[0059] (1) X-ray diffraction was performed on the Cu@C catalyst prepared in Example 1 and the Mg doped with 10 wt.% using a Bruker D8 Advance X, Cu Kα, 40 kV, 40 mA. 85 Ni 10 La 4.5 Y 0.5 The hydrogen storage material was characterized by XRD phase analysis, and the XRD curves are shown below. Figure 1 As shown, by Figure 1 It can be seen that the main phase of the Cu@C catalyst is Cu, and the diffraction peaks of the hydrogen storage material are mainly Mg, followed by Mg2Ni and the strongest Cu peak.

[0060] (2) The microstructure of the Cu@C catalyst prepared in Example 1 was characterized using a scanning electron microscope (Hitachi S-4800, 10mA, 10kV). The characterization results are as follows: Figure 2 As shown, by Figure 2 It can be seen that the calcined catalyst retains an octahedral structure.

[0061] (3) The nitrogen adsorption performance of the Cu@C catalyst prepared in Example 1 was tested using an ASAP2020M instrument. The nitrogen adsorption-desorption curves at 77 K were obtained at 298 K, as shown below. Figure 3 As shown, by Figure 3 It can be seen that the specific surface area of ​​the catalyst is 47.03 m². 2 / g

[0062] (4) The pore size of the Cu@C catalyst prepared in Example 1 was further measured using an ASAP2020M instrument. The specific pore size distribution results are as follows: Figure 4 As shown, by Figure 4 It can be seen that the catalyst has an average pore size of 3.939 nm and is a mesoporous structure.

[0063] (5) Using the PCT device manufactured by the Beijing General Research Institute of Nonferrous Metals, the Mg doping concentration of 10 wt.% was analyzed. 85 Ni 10 La4.5 Y 0.5 The hydrogen storage material underwent isothermal hydrogen absorption performance testing. Approximately 0.5 g of sample was used in each test. After the sample was fully activated (reaching 90% of its theoretical capacity), the test began. The sample was heated in a furnace at set temperatures (220℃, 240℃, and 260℃) at a heating rate of 5℃ / min, with a hydrogen pressure of 5 MPa. The test results are shown in Figure 5. Figure 5 It can be seen that the modified material absorbs 5.0742 wt.% hydrogen at 220℃ within 360s; and 5.4819 wt.% hydrogen at 260℃ within 360s.

[0064] (6) Using the PCT device produced by the Beijing General Research Institute of Nonferrous Metals, the Mg doping concentration of 10 wt.% was analyzed. 85 Ni 10 La 4.5 Y 0.5 The isothermal hydrogen release performance of hydrogen storage materials was tested. First, the sample was fully absorbed with hydrogen, and then high-pressure hydrogen gas was used to suppress hydrogen release during the heating process. The test results are as follows: Figure 6 As shown, by Figure 6 It can be seen that when the hydrogen release temperature increases from 260℃ to 280℃ and 300℃, the amount of hydrogen released within 360s increases from 2.63wt.% to 4.338wt.% and 5.5692wt.% respectively.

[0065] (7) Using the PCT device manufactured by the Beijing General Research Institute of Nonferrous Metals, the Mg doping concentration of 10 wt.% was analyzed. 85 Ni 10 La 4.5 Y 0.5 The hydrogen storage material was tested for cycle performance at 300℃, with a hydrogen absorption pressure of 5 MPa and a hydrogen dehydrogenation pressure of 0.003 MPa. Each cycle lasted 2 hours and included both hydrogen absorption and dehydrogenation steps. The results are as follows: Figure 7 As shown, in the first cycle, 5.8968 wt.% hydrogen was absorbed and 5.8266 wt.% hydrogen was removed. After 10 cycles, it was still able to absorb / remove 5.7663 wt.% / 5.6475 wt.% hydrogen respectively, and the volume retention rate after 10 cycles was still as high as 98%.

[0066] (8) Using a PCT device manufactured by the Beijing General Research Institute of Nonferrous Metals, Mg with doping amounts of 0 wt.%, 5 wt.%, 10 wt.%, and 15 wt.% was subjected to oxidation. 85 Ni 10 La 4.5 Y 0.5The hydrogen storage material underwent isothermal hydrogen absorption performance testing. Approximately 0.5 g of sample was used in each test. After the sample was fully activated (i.e., reaching 90% of its theoretical capacity), the test began. The sample was heated in a furnace at a set temperature (220℃) at a heating rate of 5℃ / min, with a hydrogen pressure of 5 MPa. The test results are shown in Figure 8. Figure 8 It can be seen that the addition of 10 wt.% Cu@C to Mg 85 Ni 10 La 4.5 Y 0.5 The material exhibits optimal hydrogen absorption performance.

[0067] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a catalyst-doped magnesium-based hydrogen storage material, characterized in that, include: Step 1: Dissolve Cu(NO3)2·H2O in deionized water to obtain solution A, and dissolve H3BTC in anhydrous ethanol to obtain solution B. Mix solution A and solution B and transfer them to an autoclave for hydrothermal reaction. After the reaction is completed, centrifuge, collect the solid, wash and vacuum dry it, and then calcine it under inert gas protection to obtain the catalyst. The calcination temperature is 350-500℃, and the holding time is 3-5 hours. Step two, the catalyst obtained in step one and Mg 85 Ni 10 La 4.5 Y 0.5 The mixture was ball-milled to obtain a catalyst-doped magnesium-based hydrogen storage material; The catalyst content in the catalyst-doped magnesium-based hydrogen storage material is 1-15 wt.%.

2. The preparation method according to claim 1, characterized in that, The mass ratio of Cu(NO3)2·H2O to H3BTC is 1:2-2.

5.

3. The preparation method according to claim 1, characterized in that, The mass-to-volume ratio of Cu(NO3)2·H2O to deionized water in solution A is 0.84-1.68 g: 18 mL.

4. The preparation method according to claim 1, characterized in that, The mass-to-volume ratio of H3BTC to anhydrous ethanol in solution B is 0.39-0.78 g: 18 mL.

5. The preparation method according to claim 1, characterized in that, The hydrothermal reaction temperature is 120-140℃, and the holding time is 12-18h.

6. The preparation method according to claim 5, characterized in that, The hydrothermal reaction temperature was 120℃ and the reaction time was 12 hours.

7. The preparation method according to claim 1, characterized in that, The ball mill speed is 300-400 r / min, the time is 3-5 h, and the ball-to-material ratio is 20:

1.

8. A catalyst-doped magnesium-based hydrogen storage material obtained by the preparation method according to any one of claims 1 to 7.

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