NiFe / CoFe nanoparticle modified magnesium-based composite hydrogen storage material and preparation method thereof
Through the coordinated catalytic modification of magnesium-based hydrogen storage materials of NiFe/CoFe nanoparticles, the high-temperature hydrogen absorption and release of magnesium-based solid hydrogen storage materials, the Mg-H bond strength and passivation layer problems are solved, and rapid hydrogen absorption and discharge and efficient hydrogenation are achieved. Hydrogen storage meets the commercialization requirements of hydrogen energy applications.
Patent Information
- Application Number
- CN202411240097.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2024-12-10
AI Technical Summary
Magnesium-based solid hydrogen storage materials have hindered the adsorption and dissociation of hydrogen due to high hydrogen absorption and release temperature, Mg-H bond strength and magnesium surface passivation layer. The existing catalyst structure is rough and the components are single, making it difficult to meet the on-board fuel cells and Requirements for commercialization and civilized hydrogen energy.
Using NiFe/CoFe nanoparticles as catalysts, the MgH2-NiFe/CoFe composite material is formed through high-temperature and high-pressure hydrogenation and short-term high-energy ball milling methods. The NiFe/CoFe nanoparticles collaboratively catalyze the modified magnesium-based hydrogen storage material to improve its hydrogen absorption and discharge power Learn performance.
The rapid hydrogen absorption and discharge characteristics and excellent kinetic properties are achieved, the process is simplified, the cost is reduced, and the hydrogen storage efficiency of hydrides is improved.
Smart Images
Figure CN119100334A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of solid-state hydrogen storage, and specifically relates to a NiFe / CoFe nanoparticle-modified magnesium-based composite hydrogen storage material and a preparation method thereof. Background Art
[0002] At present, hydrogen storage technologies mainly include high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage and metal hydride solid hydrogen storage. Although the former two have their advantages in certain scenarios, their application is limited due to low storage efficiency, high cost or safety issues. In contrast, metal hydride hydrogen storage has become the main research object of solid-state hydrogen storage materials in recent years due to its high hydrogen storage capacity and safety. Magnesium-based materials (Mg / MgH2), with their theoretical hydrogen storage capacity of up to 7.6wt.%, abundant resources and low cost, have become a research hotspot in this field.
[0003] Despite this, there are still some technical challenges for magnesium-based materials, such as high hydrogen absorption and release temperatures (>350°C), high Mg-H bond strength (-74.7 kJ / mol), and the passivation layer formed on the magnesium surface that hinders the adsorption and dissociation of hydrogen (432 kJ / mol H2). In order to overcome these obstacles, introducing catalysts to promote the hydrogen absorption and desorption process of magnesium-based materials has become an effective strategy. However, the catalysts currently used to improve magnesium-based solid-state hydrogen storage materials are mostly commercial catalysts or homemade single-component catalysts. The above catalysts have a rough structure, a single component, and the catalytic effect is often unsatisfactory, making it difficult to meet the requirements of on-board fuel cells and the commercialization and civilian use of hydrogen energy. Summary of the invention
[0004] In order to overcome the above problems in the prior art, the purpose of the present invention is to provide a NiFe / CoFe nanoparticle modified magnesium-based hydrogen storage composite material and a preparation method thereof. The composite material and the method are simple and easy to operate, and the obtained sample has excellent hydrogen absorption kinetics.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is:
[0006] A magnesium-based hydrogen storage composite material modified by NiFe / CoFe nanoparticles, which is composed of a MgH2-NiFe / CoFe composite material;
[0007] Among them, NiFe / CoFe accounts for 3-15wt.%, and the rest is MgH2. NiFe / CoFe powder is used as a catalyst to carry out synergistic catalytic modification of the MgH2 hydrogen storage material system; based on the NiFe / CoFe ternary transition metal nanoparticles loaded on the surface of MgH2, while significantly improving the kinetic properties of MgH2, it can also improve the thermodynamic properties to a certain extent, and obtain a magnesium-based composite hydrogen storage material with rapid hydrogen absorption and desorption characteristics.
[0008] Preferably, the NiFe / CoFe powder is an amorphous and irregular nanoparticle, and the diameter of the nanoparticle is 20-100 nm.
[0009] Preferably, the MgH2 is a spherical powder with a diameter of 20 to 40 mm.
[0010] Preferably, the diameter of the MgH2-NiFe / CoFe composite material is 1-6 mm.
[0011] A method for preparing a magnesium-based hydrogen storage composite material modified by NiFe / CoFe nanoparticles comprises the following steps:
[0012] Step 1: Preparation of MgH2 matrix;
[0013] High-purity magnesium powder is placed in a hydrogenation reaction vessel. Subsequently, the temperature in the reactor is slowly raised from ambient temperature to the target operating temperature according to a preset temperature rise curve. At this stage, pressure is applied to make the system enter a constant temperature and pressure state to promote the chemical combination between Mg and hydrogen. The temperature and pressure are kept constant for a certain period of time. When the hydrogenation process is completed, the reaction vessel is slowly cooled back to ambient temperature, and the generated MgH2 is separated and recovered;
[0014] Step 2: Preparation of NiFe / CoFe nanocatalyst;
[0015] Weigh sodium nitrate (C5H4FeN6Na2O3), nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and cobalt nitrate hexahydrate (Co(NO3)2·6H2O), dissolve them in deionized water in turn, and stir until a light pink opaque solution is formed, add NaCl to the above solution and continue to stir until it is completely dissolved, then seal and stand for a period of time to form a NiFe / CoFe nanoparticle precursor, use anhydrous ethanol and deionized water to alternately centrifuge and wash the NiFe / CoFe nanoparticle precursor to remove liquid impurities, dry the obtained precursor colloid in a vacuum drying oven, and then grind it with an agate mortar, and finally, calcine the ground precursor powder in a high-temperature tube furnace to obtain NiFe / CoFe powder, i.e., NiFe / CoFe nanocatalyst;
[0016] Step 3: Synchronization of matrix structure refinement and component compounding;
[0017] MgH2, NiFe / CoFe powder and stainless steel ball milling beads were weighed into a high-energy ball milling tank. After intermittent ball milling for a certain period of time under the protection of a specific atmosphere, the composite sample MgH2-NiFe / CoFe was collected.
[0018] In order to ensure that the prepared MgH2 matrix has high purity and consistency, the various process parameters in step 1 need to be limited.
[0019] In the step 1, the heating rate during the high temperature and high pressure hydrogenation process is controlled at 3-5°C / min;
[0020] The hydrogenation temperature is 320-380°C;
[0021] The hydrogenation pressure is 3-7 MPa;
[0022] The hydrogenation time is 24 to 72 hours.
[0023] In order to ensure that the prepared NiFe / CoFe nanocatalyst has excellent catalytic performance, various process parameters in step 2 need to be limited.
[0024] In step 2, the masses of C5H4FeN6Na2O3, Ni(NO3)2·6H2O and Co(NO3)2·6H2O are 0.1-0.5g, 0.2-0.8g and 0.1-0.5g respectively; the deionized water is 70-110ml; the amount of NaCl added is 3-7g; the standing time is 6-12h; the vacuum drying conditions are 60-80℃, 6-12h; and the high-temperature calcination conditions are 700-900℃, 2-6h.
[0025] Preferably, in the high-energy ball milling process of step 3, the mass ratio of MgH2 to NiFe / CoFe powder is 9.5:0.5 to 7:3;
[0026] Preferably, the ball-to-material ratio in the high-energy ball milling process of step 3 is 10 to 40:1.
[0027] The ball milling speed in the short-time high-energy ball milling process of step 3 is 600-1000 rpm;
[0028] The ball milling time in the short-time high-energy ball milling process is 15 to 60 minutes, with each ball milling time of 5 to 15 minutes and a rest time of 5 to 15 minutes.
[0029] Since a large amount of heat is generated during the long ball milling process, MgH2 will mechanically release hydrogen. Part of MgH2 will release hydrogen to form Mg and aggregate together to cause "cold welding", so it is necessary to stop and dissipate heat.
[0030] Preferably, the specific atmosphere in step 3 is H2 atmosphere; the H2 atmosphere pressure is 0.2-0.5 MPa.
[0031] Beneficial effects of the present invention:
[0032] The present invention can simultaneously realize the structural refinement of the MgH2 matrix and the composition composite of NiFe / CoFe and MgH2 by the method of short-time high-energy ball milling. NiFe / CoFe is fully loaded on the surface of MgH2 to form a large number of active sites, which can effectively accelerate the hydrogen absorption and desorption reaction. The MgH2-NiFe / CoFe composite material is prepared by mechanochemical reaction, and its process is simple, cost-effective and conditions are controllable. The intermediate phase and intermediate phase interface generated by NiFe / CoFe and MgH2 during the hydrogen absorption and desorption process can greatly improve the hydrogen absorption and desorption rate of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 Schematic diagram of the steps for preparing a magnesium-based hydrogen storage composite material modified with NiFe / CoFe nanoparticles.
[0034] Figure 2 These are the SEM images before and after the refined control of the structure of the homemade MgH2 produced in our laboratory.
[0035] Figure 3 This is the XRD spectrum of the MgH2-NiFe / CoFe composite material of the present invention.
[0036] Figure 4 This is a SEM image of the MgH2-NiFe / CoFe composite material of the present invention.
[0037] Figure 5 This is the hydrogen absorption kinetic curve of the MgH2-NiFe / CoFe composite material of the present invention at 300°C.
[0038] Figure 6 This is the dehydrogenation kinetic curve of the MgH2-NiFe / CoFe composite material of the present invention at 300°C. DETAILED DESCRIPTION
[0039] The present invention will be further described in detail below in conjunction with the accompanying drawings.
[0040] Example 1
[0041] Step 1: weigh 6 g of pure magnesium powder and put it in a high-temperature and high-pressure hydrogenation reactor. In a H2 atmosphere, the temperature is raised from room temperature to 350°C at 5°C / min, and the pressure is raised to 6 MPa and then kept warm for 72 hours. After the reaction is completed, the hydrogenation reactor is naturally cooled to room temperature, and the hydrogenation product MgH2 is collected.
[0042] Step 2, weigh 0.3g, 0.43g and 0.43g of C5H4FeN6Na2O3, Ni(NO3)2·6H2O and cobalt nitrate hexahydrate Co(NO3)2·6H2O respectively, dissolve them in 100ml of deionized water, and stir until a light pink opaque solution is formed. Add 3.5g of NaCl to the above solution and continue to stir until it is completely dissolved, then seal and stand for 10h to form a NiFe / CoFe nanoparticle precursor. Use anhydrous ethanol and deionized water to alternately centrifuge and wash the NiFe / CoFe nanoparticle precursor to remove liquid impurities. The resulting precursor colloid is dried at 60°C in a vacuum drying oven for 12h, and then ground using an agate mortar. Finally, the ground precursor powder is calcined at 800°C in a high-temperature tube furnace for 4h to obtain a NiFe / CoFe nanocatalyst.
[0043] Step 3, 0.95g, 0.05g and 20g of MgH2, NiFe / CoFe nanocatalyst and stainless steel ball milling beads were weighed respectively into a mechanochemical reaction ball mill and 0.5Mpa of H2 was introduced, and the ball milling was performed at a speed of 350rpm for 5min each time, resting for 5min, and the total ball milling was 60min to obtain a MgH2-NiFe / CoFe composite material.
[0044] The MgH2-5wt.% NiFe / CoFe composite material obtained in this example can absorb 5.80wt.% hydrogen at 300°C in 2 minutes.
[0045] Example 2
[0046] Step 1: weigh 6 g of pure magnesium powder and put it in a high-temperature and high-pressure hydrogenation reactor. In a H2 atmosphere, the temperature is raised from room temperature to 350°C at 5°C / min, and the pressure is raised to 6 MPa and then kept warm for 72 hours. After the reaction is completed, the hydrogenation reactor is naturally cooled to room temperature, and the hydrogenation product MgH2 is collected.
[0047] Step 2, weigh 0.3g, 0.43g and 0.43g of C5H4FeN6Na2O3, Ni(NO3)2·6H2O and cobalt nitrate hexahydrate Co(NO3)2·6H2O respectively, dissolve them in 100ml of deionized water, and stir until a light pink opaque solution is formed. Add 3.5g of NaCl to the above solution and continue to stir until it is completely dissolved, then seal and stand for 10h to form a NiFe / CoFe nanoparticle precursor. Use anhydrous ethanol and deionized water to alternately centrifuge and wash the NiFe / CoFe nanoparticle precursor to remove liquid impurities. The resulting precursor colloid is dried at 60°C in a vacuum drying oven for 12h, and then ground using an agate mortar. Finally, the ground precursor powder is calcined at 800°C in a high-temperature tube furnace for 4h to obtain a NiFe / CoFe nanocatalyst.
[0048] Step 3, 0.9 g, 0.1 g and 20 g of MgH2, NiFe / CoFe nanocatalyst and stainless steel ball milling beads were weighed respectively into a mechanochemical reaction ball mill and 0.5 MPa of H2 was introduced, and the ball milling was performed at a speed of 350 rpm for 5 min each time, resting for 5 min, and a total of 60 min to obtain a MgH2-NiFe / CoFe composite material.
[0049] The MgH2-10wt.% NiFe / CoFe composite material obtained in this example can absorb 5.43wt.% hydrogen at 300°C in 2 minutes.
[0050] Example 3
[0051] Step 1: weigh 6 g of pure magnesium powder and put it in a high-temperature and high-pressure hydrogenation reactor. In a H2 atmosphere, the temperature is raised from room temperature to 350°C at 5°C / min, and the pressure is raised to 6 MPa and then kept warm for 72 hours. After the reaction is completed, the hydrogenation reactor is naturally cooled to room temperature, and the hydrogenation product MgH2 is collected.
[0052] Step 2, weigh 0.3g, 0.43g and 0.43g of C5H4FeN6Na2O3, Ni(NO3)2·6H2O and Co(NO3)2·6H2O respectively, dissolve them in 100ml of deionized water in turn, and stir until a light pink opaque solution is formed. Add 3.5g of NaCl to the above solution and continue to stir until it is completely dissolved, then seal and stand for 10h to form a NiFe / CoFe nanoparticle precursor. Use anhydrous ethanol and deionized water to alternately centrifuge and wash the NiFe / CoFe nanoparticle precursor to remove liquid impurities. The resulting precursor colloid is dried at 60°C in a vacuum drying oven for 12h, and then ground using an agate mortar. Finally, the ground precursor powder is calcined at 800°C in a high-temperature tube furnace for 4h to obtain a NiFe / CoFe nanocatalyst.
[0053] Step 3, weigh 0.85g, 0.15g and 20g of MgH2, NiFe / CoFe powder and stainless steel ball milling beads respectively into a mechanochemical reaction ball mill and introduce 0.5Mpa of H2, at a speed of 350rpm, each ball milling for 5min, resting for 5min, and a total ball milling for 30min to obtain a MgH2-NiFe / CoFe composite material.
[0054] The MgH2-15wt.% NiFe / CoFe composite material obtained in this example can absorb 5.01wt.% hydrogen at 300°C in 2 minutes.
[0055] Explanation of the drawings of the present invention
[0056] Figure 1The figure is a schematic diagram of the preparation method of a magnesium-based hydrogen storage composite material modified with NiFe / CoFe nanoparticles. It can be seen from the figure that the synthesis steps can be mainly divided into three steps:
[0057] The first step is to prepare the hydrogen storage matrix material MgH2. Since commercial MgH2 has problems such as low purity and difficult quality control, the present invention uses laboratory-made MgH2. Homemade MgH2 is made by hydrogenating spherical mist magnesium powder under high temperature and high pressure, so it has problems such as large size, smooth surface, and few active sites.
[0058] The second step is the preparation of NiFe / CoFe nanocatalysts. Different transition metal salts are used to prepare a uniformly mixed multi-component transition metal ion solution through a co-precipitation method, and cheap NaCl is used as a precipitant to accelerate the precipitation degradation of the precursor mixture. The precursor is then purified and decontaminated by centrifugal washing, vacuum drying and high-temperature calcination to obtain a NiFe / CoFe nanocatalyst.
[0059] The third step is to finely regulate the structure of the MgH2 matrix through short-time high-energy ball milling, and at the same time introduce NiFe / CoFe nanocatalyst to make it evenly distributed on the surface of the MgH2 matrix, thereby achieving two effects (structural refinement and component compositeness) in one step, and finally obtaining MgH2-NiFe / CoFe composite material.
[0060] Figure 2 This is a comparison of SEM images of laboratory-made MgH2 before and after structural refinement. It can be seen from the figure that only a short period of high-energy ball milling can reduce the particle size of the MgH2 matrix to submicron level and break up the initial spherical structure to produce more active sites.
[0061] Figure 3 The XRD spectrum of the MgH2-NiFe / CoFe composite sample in Example 1. It can be seen from the spectrum that there is a strong diffraction peak of MgH2 in the composite sample, indicating that MgH2 is still the main phase and the introduction of the catalyst has not changed its structure. In addition, the presence of the characteristic diffraction peak of NiFe / CoFe indicates the successful introduction of the catalyst.
[0062] Figure 4 This is the SEM image of MgH2-NiFe / CoFe in Example 1. It can be seen that the scale of the MgH2 matrix has been significantly refined compared to before the structural refinement and more NiFe / CoFe catalyst particles are loaded on the surface, indicating that the one-step method achieves good results in structural refinement and component compounding.
[0063] Figure 5The hydrogen absorption kinetic curve of MgH25wt.%NiFe / CoFe at 300℃ in Example 1 shows that the hydrogen absorption capacity of the ball-milled magnesium hydride with optimized structure is 1.1wt.%, while under the action of NiFe / CoFe nanocatalyst, the hydrogen absorption capacity of the composite material is increased to 6.4wt.%, which is about 5.8 times of the former hydrogen absorption capacity, and 5wt.% hydrogen can be quickly absorbed within 60s, showing better hydrogen absorption kinetic performance.
[0064] Figure 6 The hydrogen desorption kinetic curve of MgH2-NiFe / CoFe at 300°C in Example 1 shows that the ball-milled magnesium hydride with optimized structure is almost difficult to release hydrogen at this temperature, while under the action of NiFe / CoFe nanocatalyst, the composite material can still release 2.3wt.% hydrogen, showing excellent hydrogen desorption kinetic performance.
Claims
1. A magnesium-based hydrogen storage composite material modified by NiFe / CoFe nanoparticles, It is characterized in that Its composition is MgH 2 -NiFe / CoFe composites; Among them, NiFe / CoFe accounts for 3-15wt.%, and the rest is MgH 2 , using NiFe / CoFe powder as catalyst for MgH 2 The hydrogen storage material system is modified by synergistic catalysis; based on the supported MgH 2 NiFe / CoFe ternary transition metal nanoparticles on the surface improve MgH 2 Kinetic and thermodynamic properties.
2. The magnesium-based hydrogen storage composite material modified by NiFe / CoFe nanoparticles according to claim 1, It is characterized in that The NiFe / CoFe powder is an amorphous and irregular nanoparticle, and the diameter of the nanoparticle is 20-100 nm.
3. The NiFe / CoFe nanoparticle-modified magnesium-based hydrogen storage composite material according to claim 1, It is characterized in that The MgH 2 It is a spherical powder with a diameter of 20 to 40 μm; The MgH 2 -The diameter of the NiFe / CoFe composite material is 1-6μm.
4. A method for preparing a NiFe / CoFe nanoparticle-modified magnesium-based hydrogen storage composite material according to any one of claims 1 to 3, It is characterized in that The following steps are involved: Step 1: MgH 2 Matrix preparation High-purity magnesium powder is placed in a hydrogenation reaction vessel. Subsequently, the temperature in the reactor is slowly raised from ambient temperature to the target operating temperature according to the preset temperature rise curve. At this stage, pressure is applied to make the system enter a constant temperature and pressure state to promote the chemical combination between Mg and hydrogen. The temperature and pressure are kept constant for a certain period of time. When the hydrogenation process is completed, the reaction vessel is slowly cooled back to ambient temperature, and the generated MgH is separated and recovered. 2 ; Step 2: Preparation of NiFe / CoFe nanocatalysts Weigh sodium nitrate (C 5 H 4 FeN 6 Na 2 O 3 ), nickel nitrate hexahydrate (Ni(NO 3 ) 2 6H 2 O) and cobalt nitrate hexahydrate (Co(NO 3 ) 2 6H 2 O), dissolved in deionized water in turn, and stirred to form a light pink opaque solution, NaCl was added to the above solution and continued to be stirred until completely dissolved, then sealed and allowed to stand for a period of time to form a NiFe / CoFe nanoparticle precursor, the NiFe / CoFe nanoparticle precursor was alternately centrifuged and washed with anhydrous ethanol and deionized water to remove liquid impurities, the obtained precursor colloid was dried in a vacuum drying oven, then ground with an agate mortar, and finally, the ground precursor powder was calcined in a high-temperature tube furnace to obtain NiFe / CoFe powder, i.e., NiFe / CoFe nanocatalyst; Step 3: Synchronization of matrix structure refinement and component complexation Weigh MgH 2 , NiFe / CoFe nanocatalysts and stainless steel ball milling beads were placed in a high-energy ball milling tank. After intermittent ball milling for a certain period of time under the protection of a specific atmosphere, the composite sample MgH 2 -NiFe / CoFe.
5. A method for preparing a NiFe / CoFe nanoparticle-modified magnesium-based hydrogen storage composite material according to claim 4, It is characterized in that In the step 1, The heating rate during the high temperature and high pressure hydrogenation process is controlled at 3 to 5°C / min; The hydrogenation temperature is 320-380°C; The hydrogenation pressure is 3-7 MPa; The hydrogenation time is 24 to 72 hours.
6. A method for preparing a NiFe / CoFe nanoparticle-modified magnesium-based hydrogen storage composite material according to claim 4, It is characterized in that During the high-energy ball milling process in step 3, MgH 2 The mass ratio of NiFe / CoFe is 9.5:0.5 to 7:3; Preferably, the ball-to-material ratio in the high-energy ball milling process of step 3 is 10 to 40:
1.
7. A method for preparing a NiFe / CoFe nanoparticle-modified magnesium-based hydrogen storage composite material according to claim 4, It is characterized in that The ball milling speed in the short-time high-energy ball milling process of step 3 is 600-1000 rpm; The ball milling time in the short-time high-energy ball milling process is 15 to 60 minutes, with each ball milling time of 5 to 15 minutes and a rest time of 5 to 15 minutes.
8. The method for preparing a NiFe / CoFe nanoparticle-modified magnesium-based hydrogen storage composite material according to claim 4, It is characterized in that The specific atmosphere in step 3 is H 2 Atmosphere; H 2 The atmosphere pressure is 0.2~0.5Mpa.
9. The method for preparing a NiFe / CoFe nanoparticle-modified magnesium-based hydrogen storage composite material according to claim 4, It is characterized in that In the step 2, The C 5 H 4 FeN 6 Na 2 O 3 ,Ni(NO 3 ) 2 6H 2 O、Co(NO 3 ) 2 6H 2 The masses of O are 0.1-0.5 g, 0.2-0.8 g and 0.1-0.5 g respectively; The deionized water is 70-110 ml; The amount of NaCl added is 3 to 7 g; The standing time is 6 to 12 hours; The vacuum drying condition is 60-80°C for 6-12h; The high temperature calcination conditions are 700-900° C. for 2-6 hours.