A catalyst for hydrogen storage materials, its preparation method and application

Abstract

This invention provides a catalyst for hydrogen storage materials, its preparation method, and its application. The catalyst comprises CeO2 nanorods and transition metal nanoclusters supported on the CeO2 nanorods; the transition metal nanoclusters include any two of Ni, Pd, Co, or Mn elements. In this catalyst, the CeO2 nanorods can form a strong metal-support interaction with the transition metal nanoclusters, synergistically improving the hydrogen storage kinetics of MgH2 material. Simultaneously, the transition metal nanoclusters containing two of the aforementioned elements can effectively improve the hydrogen absorption / desorption performance of MgH2. Therefore, by combining this catalyst with MgH2 material, the hydrogen desorption temperature of MgH2 can be reduced, the hydrogen absorption / desorption kinetics of MgH2 can be improved, and the cycling performance can be enhanced.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen storage technology, and relates to a catalyst for hydrogen storage materials, its preparation method and application. Background Technology

[0002] Hydrogen energy is an ideal energy source. However, due to the mismatch between hydrogen supply and demand in the entire hydrogen energy industry chain, hydrogen storage and transportation have become crucial for the large-scale industrial application of hydrogen. Nevertheless, the storage and transportation of hydrogen is challenging, becoming a major bottleneck restricting the development of the hydrogen energy industry. Achieving low-cost, high-efficiency, high-safety, and high-density reversible hydrogen storage has become key to the large-scale development of the hydrogen energy industry. Currently, the main hydrogen storage technologies under research and development include four types: high-pressure gaseous hydrogen storage, solid-state hydrogen storage, organic-liquid hydrogen storage, and cryogenic liquid hydrogen storage. Among these, solid-state hydrogen storage technology, due to its advantages such as mild hydrogen absorption / desorption pressure, high safety attributes, low leakage rate, and high volumetric hydrogen storage density, has been used for hydrogen supply in mobile testing instruments and fuel cells. It is also used for hydrogen purification and efficient hydrogen pressurization in hydrogen refueling stations, and is particularly being promoted and applied in some hydrogen fuel cell vehicles.

[0003] Among solid-state hydrogen storage materials, MgH2 exhibits a high hydrogen storage density of 7.6 wt.%, significantly exceeding the theoretical hydrogen storage densities of several alloys. Therefore, it is more favored by researchers. The enthalpy of reaction of MgH2, ΔH, is approximately -75 kJ / mol. -1 MgH2 is an ionic hydride with strong ionic bonds, requiring higher temperatures (above 300℃) to break the Mg-H bonds and release hydrogen. Furthermore, its hydrogen absorption / desorption rate is slow, which is difficult to meet the rate requirements of hydrogen storage devices, severely restricting its commercial development in hydrogen storage materials.

[0004] Therefore, a solution is needed to reduce the hydrogen desorption temperature of MgH2 materials and increase their hydrogen absorption / desorption rate. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a catalyst for hydrogen storage materials, its preparation method, and its application. The catalyst for hydrogen storage materials provided by the present invention comprises CeO2 nanorods and transition metal nanoclusters supported on the CeO2 nanorods. When combined with MgH2 material, it can significantly reduce the hydrogen desorption temperature of MgH2, improve the hydrogen absorption / desorption kinetics of MgH2, and increase its hydrogen absorption / desorption rate.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a catalyst for hydrogen storage materials, the catalyst comprising CeO2 nanorods and transition metal nanoclusters supported on CeO2 nanorods;

[0008] The transition metal nanoclusters include any two of the elements Ni, Pd, Co, or Mn.

[0009] The hydrogen storage material catalyst provided by this invention uses CeO2 nanorods as a support, which has low cost and excellent catalytic performance. It also possesses a large number of oxygen vacancies, enabling it to form strong metal-support interactions with transition metal nanoclusters, resulting in a synergistic effect that improves the kinetic performance of MgH2 materials. Furthermore, its nanorod morphology allows it to act as a cutting agent in the composite process with MgH2 materials, further reducing the particle size of MgH2 and increasing the contact area between the catalyst and MgH2, thereby further enhancing the hydrogen storage kinetic performance of MgH2 materials. Simultaneously, Ce in the CeO2 nanorods is a rare earth metal element with abundant energy levels and unique 4f electron transition characteristics.

[0010] Transition metal nanoclusters include any two of Ni, Pd, Co, or Mn elements. Among them, Ni, Co, and Mn are all 3d transition metal elements. Therefore, it can be concluded that transition metal nanoclusters contain at least one 3d transition metal element. The introduction of 3d transition metal elements can effectively improve the hydrogen absorption / desorption performance of MgH2, mainly due to the special electronic structure of 3d transition metals. They can form hydrides with hydrogen and play the role of "overflow" or "hydrogen pump" in the hydrogen absorption / desorption process. Because transition metal hydrides are thermodynamically less stable than pure Mg, they will first release hydrogen atoms during the hydrogen absorption / desorption process, thus playing the role of "hydrogen transport". Pb element exhibits a unique electronic configuration during dehydrogenation, which can improve the surface activity of the material and can catalyze the breaking of Mg-H bonds, thereby reducing the dehydrogenation temperature of MgH2.

[0011] The synergistic effect of CeO2 nanorods and transition metal nanoclusters in the catalyst can improve the hydrogen absorption / desorption activity of the MgH2 material surface, grain boundaries and phase boundaries, provide nucleation cores, thereby reducing the nucleation energy barrier of MgH2 and the activation energy of the entire hydrogen absorption / desorption process; it can also reduce the dissociation energy of hydrogen molecules on the magnesium surface (the original dissociation energy is relatively high at 1.15 eV); at the same time, the interaction between the unsaturated d / f electron layer of the metal in the catalyst and the valence electrons of H will weaken the Mg-H bond, thereby improving the hydrogen desorption performance of MgH2 material;

[0012] In summary, by combining the catalyst of this invention with MgH2 material, the hydrogen desorption temperature of MgH2 can be significantly reduced, the hydrogen absorption / desorption kinetics of MgH2 can be improved, its hydrogen absorption / desorption rate can be increased, and its cycle performance can be improved. Furthermore, it has the characteristics of being lightweight and low cost, making the resulting hydrogen storage material have the potential for on-board hydrogen storage applications.

[0013] Preferably, the length of the CeO2 nanorod is 50-80 nm, for example, it can be 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm or 80 nm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] Preferably, the CeO2 nanorods have a diameter of 7-8 nm, such as 7 nm, 7.2 nm, 7.4 nm, 7.6 nm, 7.8 nm or 8 nm, but are not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, the transition metal nanoclusters include Ni and Pd elements.

[0016] In this invention, under the synergistic effect of Ni, Pd, and CeO2 nanorods in transition metal nanoclusters, a catalyst containing very little Pd can significantly reduce the hydrogen desorption temperature of MgH2, improve the hydrogen absorption / desorption kinetics of MgH2, and increase the hydrogen absorption / desorption rate, thus significantly reducing the amount of Pd noble metal element used and significantly reducing the cost of the catalyst. At the same time, Ni and Pd can form Mg6Ni / Mg6Pd clusters during the hydrogen absorption / desorption process, co-catalyzing MgH2, which can make the hydrogen storage material obtained by combining the catalyst and MgH2 material have a higher hydrogen storage capacity and a faster hydrogen absorption / desorption rate.

[0017] Preferably, the ratio of the total number of Ni and Pd atoms to the number of CeO2 nanorods is 0.05-0.3, for example, it can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29 or 0.30, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0018] This invention employs trace loading of Pd and Ni elements onto CeO2 nanorods, which significantly reduces the amount of precious metals used and lowers catalyst costs. The catalyst cost of this invention, which uses trace loading of Pd and Ni elements onto CeO2 nanorods, is far lower than the cost of a composite catalyst of Pd and Ni.

[0019] Preferably, the molar ratio of Ni to Pd is (1-3):(1-3), wherein the range of Ni can be, for example, 1, 2 or 3, and the range of Pd can be, for example, 1, 2 or 3, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Preferably, the transition metal nanoclusters include Co and Mn elements.

[0021] In this invention, when the transition metal elements in the transition metal nanoclusters are composed of Co and Mn, they can also reduce the hydrogen desorption temperature of MgH2, improve the hydrogen absorption / desorption kinetics of MgH2, and increase the hydrogen absorption / desorption rate. However, due to the poor reversibility of hydrogen absorption / desorption of compounds such as Mg2Co and MnO2 formed by Co, Mn and Mg, the hydrogen storage material obtained by combining the catalyst with MgH2 material has a slightly lower hydrogen storage capacity than the combination of Ni and Pd elements.

[0022] Preferably, the ratio of the total number of Co and Mn atoms to the number of CeO2 nanorods is 0.05-0.3, for example, it can be 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29 or 0.30, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0023] Preferably, the molar ratio of Co to Mn is (1-3):(1-3), wherein the range of Co can be, for example, 1, 2 or 3, and the range of Mn can be, for example, 1, 2 or 3, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] In a second aspect, the present invention provides a method for preparing the catalyst for the hydrogen storage material described in the first aspect, the method comprising:

[0025] (1) CeO2 nanorods, a transition metal source and a solvent are mixed and loaded to obtain a loaded product; wherein the transition metal source includes any two of Ni source, Pd source, Co source or Mn source;

[0026] (2) The loaded product is subjected to a heating reduction reaction to obtain the catalyst for the hydrogen storage material.

[0027] This invention achieves the loading of transition metal nanoclusters on CeO2 nanorods through deposition precipitation and thermal reduction methods, thereby obtaining a catalyst for hydrogen storage materials.

[0028] Preferably, the method for preparing the CeO2 nanorods in step (1) includes:

[0029] (a) A solution containing a Ce source and a solution containing a precipitant are mixed and then subjected to a hydrothermal reaction to obtain the hydrothermal reaction product;

[0030] (b) The hydrothermal reaction product is calcined to obtain the CeO2 nanorods.

[0031] The CeO2 nanorods prepared by the hydrothermal method in this invention are more suitable as catalyst supports.

[0032] Preferably, the Ce source comprises a Ce salt.

[0033] Optionally, the Ce salt includes Ce(NO3)3·6H2O.

[0034] Preferably, the precipitant comprises an alkaline substance.

[0035] Optionally, the alkaline substance includes NaOH.

[0036] Preferably, the temperature of the hydrothermal reaction is 90-110℃, for example, 90℃, 95℃, 100℃, 105℃ or 110℃; the time of the hydrothermal reaction is 22-26h, for example, 22h, 23h, 24h, 25h or 26h, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] Preferably, the calcination temperature is 380-420℃, for example, it can be 380℃, 390℃, 400℃, 410℃ or 420℃, etc.; the calcination time is 3-5h, for example, it can be 3h, 4h or 5h, etc., but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0038] Preferably, the transition metal source in step (1) includes a Ni source and a Pd source.

[0039] Preferably, the Ni source includes NiCl2 and / or NiCl2·6H2O; the Pd source includes H2PdCl4 and / or PdCl2.

[0040] Preferably, the transition metal source in step (1) includes a Co source and a Mn source.

[0041] Preferably, the Co source includes CoCl2 and / or Co(NO3)2·6H2O; the Mn source includes MnCl2 and / or KMnO4.

[0042] Preferably, the mixing in step (1) specifically includes the following steps: first, a first mixing is performed, and then a pH adjuster is added dropwise until the pH value of the system is 9-10 (for example, it can be 9, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9 or 10, etc.), and then a second mixing is performed.

[0043] Optionally, the pH adjuster includes sodium carbonate.

[0044] Preferably, both the first mixing and the second mixing processes are accompanied by stirring.

[0045] Preferably, the first mixing time is 20-40 minutes, for example, it can be 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the second mixing time is 1-3 hours, for example, it can be 1 hour, 2 hours or 3 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] Preferably, the atmosphere for the heating reduction reaction in step (2) is a reducing atmosphere.

[0048] Preferably, the gases in the reducing atmosphere include hydrogen and argon; the volume ratio of the hydrogen to the argon is (1-2):(8-9), for example, it can be 1:9 or 2:8, and other unlisted values ​​within this range are also applicable.

[0049] Preferably, the temperature of the heating reduction reaction is 380-420℃, for example, it can be 380℃, 390℃, 400℃, 410℃ or 420℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the heating reduction reaction time is 3-5 hours, for example, 3 hours, 4 hours or 5 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0051] As a preferred technical solution of the present invention, the preparation method specifically includes the following steps:

[0052] (I) Ce(NO3)3·6H2O was dissolved in water to obtain a Ce source solution, and NaOH was dissolved in water to obtain a precipitant solution. Under stirring, the Ce source solution and the precipitant solution were rapidly mixed and stirred for 1-2 hours at room temperature. Then, a hydrothermal reaction was carried out at 90-110℃ for 22-26 hours. After that, the mixture was washed and vacuum dried to obtain the hydrothermal reaction product. The hydrothermal reaction product was calcined at 380-420℃ for 3-5 hours to obtain CeO2 nanorods.

[0053] (II) The CeO2 nanorods, NiCl2 and H2PtCl4 were dispersed in water and stirred at room temperature for 20-40 min. Then, a pH adjuster was added dropwise until the pH of the system was 9-10. The mixture was then stirred for 1-3 h to load the product. After that, the product was washed and vacuum dried to obtain the loaded product.

[0054] (III) The supported product is subjected to a heating reduction reaction at 380-420°C for 3-5 hours in a reducing atmosphere of hydrogen and argon to obtain the catalyst for the hydrogen storage material.

[0055] Thirdly, the present invention provides a hydrogen storage material, which is obtained by ball milling MgH2 material and the hydrogen storage material described in the first aspect with a catalyst.

[0056] Preferably, based on the total mass of the hydrogen storage material, the mass fraction of the catalyst used in the hydrogen storage material is 5-15%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, etc., but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the ball milling speed is 450-500 rpm, for example, 450 rpm, 460 rpm, 480 rpm or 500 rpm; the ball milling time is 20-25 h, for example, 20 h, 21 h, 22 h, 23 h, 24 h or 25 h, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0058] In this invention, when the ball milling time is controlled to be 20-25 hours, the particle size of the hydrogen storage material can be made smaller, the uniformity of phase distribution can be improved, thereby improving the hydrogen absorption / desorption kinetics and cycle performance.

[0059] For example, the present invention provides a specific method for preparing hydrogen storage materials, comprising:

[0060] Under an inert atmosphere, MgH2 material, hydrogen storage material, catalyst, and stainless steel beads are placed in a ball mill jar and sealed. Hydrogen gas is introduced into the jar, and then the mixture is ball milled at a speed of 450-500 for 20-25 hours to obtain the hydrogen storage material.

[0061] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0062] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0063] The hydrogen storage material catalyst provided by this invention uses CeO2 nanorods as a support, which has low cost and excellent catalytic performance. It also possesses a large number of oxygen vacancies, enabling it to form strong metal-support interactions with transition metal nanoclusters, resulting in a synergistic effect that improves the kinetic performance of MgH2 materials. Furthermore, its nanorod morphology allows it to act as a cutting agent in the composite process with MgH2 materials, further reducing the particle size of MgH2 and increasing the contact area between the catalyst and MgH2, thereby further enhancing the hydrogen storage kinetic performance of MgH2 materials. Simultaneously, Ce in the CeO2 nanorods is a rare earth metal element with abundant energy levels and unique 4f electron transition characteristics.

[0064] Transition metal nanoclusters include any two of Ni, Pd, Co, or Mn elements. Among them, Ni, Co, and Mn are all 3d transition metal elements. Therefore, it can be concluded that transition metal nanoclusters contain at least one 3d transition metal element. The introduction of 3d transition metal elements can effectively improve the hydrogen absorption / desorption performance of MgH2, mainly due to the special electronic structure of 3d transition metals. They can form hydrides with hydrogen and play the role of "overflow" or "hydrogen pump" in the hydrogen absorption / desorption process. Because transition metal hydrides are thermodynamically less stable than pure Mg, they will first release hydrogen atoms during the hydrogen absorption / desorption process, thus playing the role of "hydrogen transport". Pb element exhibits a unique electronic configuration during dehydrogenation, which can improve the surface activity of the material and can catalyze the breaking of Mg-H bonds, thereby reducing the dehydrogenation temperature of MgH2.

[0065] The synergistic effect of CeO2 nanorods and transition metal nanoclusters in the catalyst can improve the hydrogen absorption / desorption activity of the MgH2 material surface, grain boundaries and phase boundaries, provide nucleation cores, thereby reducing the nucleation energy barrier of MgH2 and the activation energy of the entire hydrogen absorption / desorption process; it can also reduce the dissociation energy of hydrogen molecules on the magnesium surface; at the same time, the interaction between the unsaturated d / f electron layer of the metal in the catalyst and the valence electrons of H will weaken the Mg-H bond, thereby improving the hydrogen desorption performance of MgH2 material;

[0066] In summary, by combining the catalyst of this invention with MgH2 material, the hydrogen desorption temperature of MgH2 can be significantly reduced, the hydrogen absorption / desorption kinetics of MgH2 can be improved, its hydrogen absorption / desorption rate can be increased, and its cycle performance can be improved. Furthermore, it has the characteristics of being lightweight and low cost, making the resulting hydrogen storage material have the potential for on-board hydrogen storage applications. Attached Figure Description

[0067] Figure 1 This is a TEM image of the catalyst for hydrogen storage materials provided in Example 3 of the present invention.

[0068] Figure 2 This is a SEM image of the hydrogen storage material provided in Example 3 of this invention.

[0069] Figure 3 The hydrogen storage material provided in Example 3 of this invention exhibits dehydrogenation test curves at different temperatures.

[0070] Figure 4 The hydrogen absorption test curves of the hydrogen storage material provided in Example 3 of this invention at different temperatures are shown.

[0071] Figure 5 The hydrogen storage material provided in Comparative Example 1 of this invention exhibits dehydrogenation test curves at different temperatures.

[0072] Figure 6 The hydrogen absorption test curves of the hydrogen storage material provided in Comparative Example 1 of this invention at different temperatures are shown. Detailed Implementation

[0073] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0074] Example 1

[0075] This embodiment provides a catalyst for hydrogen storage materials, including CeO2 nanorods and transition metal nanoclusters supported on CeO2 nanorods;

[0076] The CeO2 nanorods are 50-80 nm in length and 7-8 nm in diameter; the transition metal elements in the transition metal nanoclusters are composed of Ni and Pd elements; the ratio of the total number of Ni and Pd atoms to the number of CeO2 nanorod atoms is 0.05, and the molar ratio of Ni to Pd is 1:1; the hydrogen storage material is denoted as a catalyst of 0.05NiPd / CeO2.

[0077] This embodiment also provides a method for preparing the catalyst for the above-mentioned hydrogen storage material, including the following steps:

[0078] (1) Prepare the materials according to the composition of the 0.05NiPd / CeO2 catalyst;

[0079] (2) Ce(NO3)3·6H2O and NaOH were dispersed in deionized water to form two solutions. After stirring the two solutions thoroughly, they were quickly mixed and stirred for 1 hour. The samples were then transferred to a reaction vessel and hydrothermally reacted at 100°C for 24 hours. The material obtained after the hydrothermal reaction was washed with deionized water until neutral, and then washed again with anhydrous ethanol. Afterward, it was vacuum dried at 80°C for 12 hours, ground, and passed through a 100-mesh molecular sieve. The sieved sample was then transferred to a muffle furnace and calcined at 400°C for 4 hours to synthesize CeO2 nanorods.

[0080] (3) The synthesized CeO2 nanorod support was dispersed together with NiCl2 and H2PdCl4 in deionized water. After stirring at room temperature for 30 minutes, 1M Na2CO3 solution was added dropwise to adjust the pH of the system to 9. Then, the system was continuously stirred for 2 hours for loading. The obtained material was washed with deionized water until neutral, and then washed again with anhydrous ethanol. It was vacuum dried at 80°C for 12 hours and then vacuum dried. The dried sample was transferred to a tube furnace and heated at 400°C for 4 hours in a mixed atmosphere of H2 and Ar with a volume ratio of 1:9 to obtain a catalyst for hydrogen storage materials.

[0081] This embodiment also provides a method for preparing a hydrogen storage material, including the following steps:

[0082] In an argon-filled glove box, the hydrogen storage material, catalyst, MgH2 material, and stainless steel balls were transferred together into a stainless steel ball mill jar and sealed. Then, hydrogen gas at 3 MPa was introduced, and the mixture was ball-milled at 500 rpm for 24 hours to obtain 0.0952 g of hydrogen storage material. Based on the total mass of the hydrogen storage material, the mass fraction of the catalyst in the hydrogen storage material was 10%, and the hydrogen storage material was designated as MgH2-10wt.%0.05NiPd / CeO2.

[0083] Example 2

[0084] The difference between this embodiment and Embodiment 1 is that in the catalyst for hydrogen storage materials, the ratio of the total number of Ni and Pd atoms to the number of CeO2 nanorods is 0.1.

[0085] The remaining parameters are the same as in Example 1.

[0086] Example 3

[0087] The difference between this embodiment and Embodiment 1 is that in the catalyst for hydrogen storage materials, the ratio of the total number of Ni and Pd atoms to the number of CeO2 nanorods is 0.2.

[0088] The remaining parameters are the same as in Example 1.

[0089] Figure 1 The image shows a TEM image of the catalyst for hydrogen storage materials provided in this embodiment. As can be seen from the image, nanoclusters are loaded on the nanorods.

[0090] Figure 2 The image shows a SEM image of the hydrogen storage material provided in this embodiment. As can be seen from the image, the hydrogen storage material has a small particle size.

[0091] Under a pressure of 0.001 MPa H2, a programmed temperature rise method was used to raise the temperature to different set temperatures (250℃, 275℃, 300℃, 325℃, and 350℃) at a rate of 5℃ / min to test the dehydrogenation performance of the hydrogen storage material provided in this embodiment at different temperatures. The test results are as follows: Figure 3 As shown in the figure, the hydrogen storage material of the present invention can release 6.4 wt.% hydrogen in 500s at 350°C; and dehydrogenate 5.5 wt.% in 2000s at 275°C.

[0092] The hydrogen storage material provided in this embodiment was heated to 350°C at a rate of 5°C / min under 0.001 MPa H2 conditions, held for 10 minutes, then evacuated and cooled to room temperature to achieve hydrogen removal. Subsequently, hydrogen absorption performance was tested: under 5.0 MPa H2 conditions, the temperature was programmed to different set temperatures (100°C, 150°C, 200°C, and 250°C) at a rate of 5°C / min. The hydrogen absorption performance of the hydrogen storage material provided in this embodiment at different temperatures was tested, and the test results are as follows: Figure 4 As shown in the figure, the hydrogen storage material of the present invention can absorb 6.4 wt.% hydrogen within 40 seconds at 250°C; and 4 wt.% hydrogen within 2500 seconds at 100°C.

[0093] In summary, by Figure 3 and Figure 4 As can be seen, the hydrogen storage material provided in this embodiment exhibits excellent hydrogen absorption / desorption kinetics, with a fast hydrogen absorption / desorption rate, and still possesses excellent hydrogen absorption / desorption performance at low temperatures.

[0094] Example 4

[0095] The difference between this embodiment and Embodiment 1 is that in the catalyst for hydrogen storage materials, the ratio of the total number of Ni and Pd atoms to the number of CeO2 nanorods is 0.3.

[0096] The remaining parameters are the same as in Example 1.

[0097] Example 5

[0098] The difference between this embodiment and Embodiment 3 is that, in the hydrogen storage material, based on the total mass of the hydrogen storage material, the mass fraction of the catalyst used in the hydrogen storage material is 5%.

[0099] The remaining parameters are the same as in Example 3.

[0100] Example 6

[0101] The difference between this embodiment and Embodiment 3 is that, based on the total mass of the hydrogen storage material, the mass fraction of the catalyst used in the hydrogen storage material is 15%.

[0102] The remaining parameters are the same as in Example 3.

[0103] Example 7

[0104] The difference between this embodiment and Embodiment 3 is that the ball milling time is 12 hours during the preparation of the hydrogen storage material.

[0105] The remaining parameters are the same as in Example 3.

[0106] Example 8

[0107] The difference between this embodiment and embodiment 3 is that the equimolar amount of NiCl2 in step (3) is replaced with CoCl2, and the equimolar amount of H2PdCl4 is replaced with KMnO4, so that the catalyst for hydrogen storage material includes CeO2 nanorods and CoMn nanoclusters supported on CeO2 nanorods.

[0108] The remaining parameters are the same as in Example 3.

[0109] Comparative Example 1

[0110] The difference between this comparative example and Example 3 is that no catalyst for hydrogen storage materials is added during the preparation of the hydrogen storage material.

[0111] The remaining parameters are the same as in Example 3.

[0112] Under conditions of 0.001 MPa H2, a programmed temperature rise method was used, with a heating rate of 5 °C / min, to different set temperatures (250 °C, 275 °C, 300 °C, 325 °C, and 350 °C) to test the dehydrogenation performance of the hydrogen storage material provided in this comparative example at different temperatures. The test results are as follows: Figure 5 As shown in the figure, the dehydrogenation rate is slow without the addition of a catalyst, and the amount of hydrogen released after 2500 s at 275 °C is only 1.1 wt.%.

[0113] The hydrogen storage material provided in this comparative example was heated to 350°C at a programmed heating rate of 5°C / min under 0.001 MPa H2 conditions, held for 10 min, then evacuated and cooled to room temperature to achieve hydrogen removal. Subsequently, hydrogen absorption performance was tested: under 5.0 MPa H2 conditions, the temperature was programmed at a heating rate of 5°C / min to different set temperatures (100°C, 150°C, 200°C, and 250°C) to test the hydrogen absorption performance of the hydrogen storage material provided in this comparative example at different temperatures. The test results are as follows: Figure 6 As shown in the figure, the hydrogen absorption rate is very slow without the addition of a catalyst.

[0114] Comparative Example 2

[0115] The difference between this comparative example and Example 3 is that NiCl2 is not added when preparing the catalyst for hydrogen storage materials, so that the catalyst for hydrogen storage materials does not contain Ni elements.

[0116] The remaining parameters are the same as in Example 3.

[0117] Comparative Example 3

[0118] The difference between this comparative example and Example 3 is that H2PdCl4 is not added when preparing the catalyst for hydrogen storage materials, so that the catalyst for hydrogen storage materials does not contain Pd elements.

[0119] The remaining parameters are the same as in Example 3.

[0120] Comparative Example 4

[0121] The difference between this comparative example and Example 3 is that NiCl2 and H2PdCl4 are not added when preparing the catalyst for hydrogen storage materials, so that the catalyst for hydrogen storage materials does not contain Ni and Pd elements.

[0122] The remaining parameters are the same as in Example 3.

[0123] The hydrogen storage materials provided in the above embodiments and comparative examples were subjected to the following tests:

[0124] ① Under the condition of 0.001 MPa H2, the hydrogen storage material was heated by programmed heating at a rate of 2 °C / min. When the amount of dehydrogenation reached 0.1 wt.%, the corresponding dehydrogenation temperature was recorded as the initial dehydrogenation temperature.

[0125] ② Under the condition of 0.001 MPa H2, the hydrogen storage material was heated to 300℃ at a programmed heating rate of 5℃ / min, and the time taken for complete dehydrogenation was recorded.

[0126] ③ The hydrogen storage material was heated to 350℃ at a rate of 5℃ / min under 0.001 MPa H2 conditions, held for 10 min, then the gas was evacuated and cooled to room temperature to achieve dehydrogenation. Subsequently, the hydrogen absorption capacity was tested: under 5.0 MPa H2 conditions, the temperature was increased to 100℃ at a rate of 5℃ / min, and the hydrogen absorption was treated at a constant temperature for 2500 s, and the hydrogen absorption capacity was recorded.

[0127] ④ Under the condition of 0.001 MPa H2, the hydrogen storage material was heated by programmed heating at a rate of 2 °C / min, and the maximum amount of hydrogen dehydrogenation after complete dehydrogenation was recorded.

[0128] ⑤ The hydrogen storage material was heated to 350℃ at a rate of 5℃ / min under 0.001 MPa H2 conditions, held for 10 min, then the gas was evacuated and cooled to room temperature to achieve dehydrogenation. Subsequently, a cycle performance test was conducted: at 300℃, the hydrogen storage material was allowed to absorb hydrogen for 30 min under 5.0 MPa H2 conditions and release hydrogen for 15 min under 0.001 MPa H2 conditions. After 20 cycles of hydrogen absorption and release, the ratio of the hydrogen absorption amount in the 20th cycle to the hydrogen absorption amount in the 1st cycle was calculated to obtain the hydrogen storage retention rate.

[0129] The test results are shown in Table 1.

[0130] Table 1

[0131]

[0132]

[0133] analyze:

[0134] As can be seen from Examples 1-6, the catalyst for hydrogen storage materials provided by the present invention includes CeO2 nanorods and a trace amount of NiPd nanoclusters supported on CeO2 nanorods. This can greatly reduce the amount of precious metals used. By combining this hydrogen storage material catalyst with MgH2 material, a hydrogen storage material with low hydrogen desorption temperature, fast reversible hydrogen absorption / desorption rate, high hydrogen storage capacity and good cycle performance can be obtained.

[0135] As can be seen from the comparison between Example 3 and Example 7, if the ball milling time is reduced, the particle size of the hydrogen storage material will increase, the uniformity of phase distribution will decrease, the kinetics will slow down, and the cycle performance will deteriorate.

[0136] As can be seen from Examples 3 and 8, Example 8 provides a catalyst for hydrogen storage materials comprising CeO2 nanorods and a trace amount of CoMn nanoclusters supported on the CeO2 nanorods. By combining this catalyst for hydrogen storage materials with MgH2 material, it is also possible to reduce the hydrogen dehydrogenation temperature of the hydrogen storage material, improve the reversible hydrogen absorption / dehydrogenation rate and cycle performance, but the effect is slightly worse than the catalyst supported on NiPd element in Example 3. Furthermore, the maximum dehydrogenation capacity of the hydrogen storage material provided in Example 8 is lower than that in Example 3, that is, the hydrogen storage capacity is lower than that in Example 3.

[0137] As can be seen from the comparison between Example 3 and Comparative Example 1, if no catalyst is added, the hydrogen storage material obtained is still MgH2, which has a high initial dehydrogenation temperature, above 300°C, and will lead to an increase in the particle size of the hydrogen storage material, greatly slowing down the hydrogen absorption / desorption kinetics and deteriorating the cycle performance.

[0138] As can be seen from the comparison between Example 3 and Comparative Example 2, if the catalyst used for hydrogen storage materials does not contain Ni, the catalytic effect of the catalyst will be weakened and the hydrogen absorption / desorption kinetics will be slowed down.

[0139] As can be seen from the comparison between Example 3 and Comparative Example 3, if the catalyst used for hydrogen storage materials does not contain Pd, the catalytic effect of the catalyst will be weakened and the hydrogen absorption / desorption kinetics will be slowed down.

[0140] As can be seen from the comparison between Example 3 and Comparative Example 4, if the catalyst used for hydrogen storage materials does not contain Ni and Pd elements, the catalytic effect of the catalyst will be greatly weakened and the hydrogen absorption / desorption kinetics will be slowed down.

[0141] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A hydrogen storage material, characterized in that, The hydrogen storage material is obtained by ball milling MgH2 material and hydrogen storage material with a catalyst. The catalyst for the hydrogen storage material includes CeO2 nanorods and transition metal nanoclusters supported on CeO2 nanorods. The transition metal nanoclusters are composed of Co and Mn elements.

2. The hydrogen storage material according to claim 1, characterized in that, The CeO2 nanorods have a length of 50-80 nm.

3. The hydrogen storage material according to claim 1, characterized in that, The CeO2 nanorods have a diameter of 7-8 nm.

4. The hydrogen storage material according to claim 1, characterized in that, The ratio of the total number of Co and Mn atoms to the number of CeO2 nanorods is 0.05-0.

3.

5. The hydrogen storage material according to claim 1, characterized in that, The molar ratio of Co to Mn is (1-3):(1-3).

6. The hydrogen storage material according to claim 1, characterized in that, Based on the total mass of the hydrogen storage material, the mass fraction of the catalyst used in the hydrogen storage material is 5-15%.

7. The hydrogen storage material according to claim 1, characterized in that, The ball mill rotates at 450-500 rpm; the ball milling time is 20-25 hours.

8. The hydrogen storage material according to claim 1, characterized in that, The method for preparing the catalyst includes: (1) CeO2 nanorods, a transition metal source and a solvent are mixed and loaded to obtain a loaded product; wherein the transition metal source is a Co source and a Mn source; (2) The loaded product is subjected to a heating reduction reaction to obtain the catalyst for the hydrogen storage material.

9. The hydrogen storage material according to claim 8, characterized in that, The preparation method of CeO2 nanorods in step (1) includes: (a) A solution containing a Ce source and a solution containing a precipitant are mixed and then subjected to a hydrothermal reaction to obtain the hydrothermal reaction product; (b) The hydrothermal reaction product is calcined to obtain the CeO2 nanorods.

10. The hydrogen storage material according to claim 9, characterized in that, The Ce source includes Ce salt.

11. The hydrogen storage material according to claim 9, characterized in that, The precipitant includes an alkaline substance.

12. The hydrogen storage material according to claim 9, characterized in that, The hydrothermal reaction temperature is 90-110℃, and the hydrothermal reaction time is 22-26h.

13. The hydrogen storage material according to claim 9, characterized in that, The calcination temperature is 380-420℃, and the calcination time is 3-5 hours.

14. The hydrogen storage material according to claim 8, characterized in that, The mixing in step (1) specifically includes the following steps: first, a first mixing is performed, then a pH adjuster is added dropwise until the pH value of the system is 9-10, and then a second mixing is performed.

15. The hydrogen storage material according to claim 14, characterized in that, Both the first and second mixing processes are accompanied by stirring.

16. The hydrogen storage material according to claim 14, characterized in that, The first mixing time is 20-40 minutes.

17. The hydrogen storage material according to claim 14, characterized in that, The second mixing time is 1-3 hours.

18. The hydrogen storage material according to claim 8, characterized in that, The atmosphere for the heating reduction reaction in step (2) is a reducing atmosphere.

19. The hydrogen storage material according to claim 18, characterized in that, The reducing atmosphere contains hydrogen and argon; the volume ratio of hydrogen to argon is (1-2):(8-9).

20. The hydrogen storage material according to claim 8, characterized in that, The temperature of the heating reduction reaction is 380-420℃.

21. The hydrogen storage material according to claim 8, characterized in that, The heating reduction reaction takes 3-5 hours.

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