High-entropy alloy hydride material and preparation method and application thereof

Abstract

The invention discloses a high-entropy alloy hydride material which is a metal hydride and comprises the following metal elements in percentage by mass: 15-25% of Ti, 15-25% of Nb, 15-25% of V, 15-25% of Hf, 15-25% of Zr and the balance of H. The preparation method of the high-entropy alloy hydride material comprises the following steps: (1) in an argon atmosphere, mixing niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, titanium tetrachloride and vanadium trichloride in proportion, adding anhydrous lithium chloride, and carrying out ball milling; (2) adding lithium hydride, and carrying out ball milling and sample tamping; (3) carrying out repeated ultrasonic cleaning and centrifugation on the obtained substance, and collecting a solid precipitate; and (4) the obtained solid precipitate is subjected to vacuum drying and grinding, and the high-entropy alloy hydride material is obtained. The prepared material has excellent thermocatalytic performance, the preparation method is simple and efficient, and the hydrogen absorption and desorption performance and reversibility of MgH2 can be effectively improved.

Description

Technical Field

[0001] The present invention relates to a thermal catalytic composite material and a preparation method and application thereof, in particular to a high entropy alloy hydride material and a preparation method and application thereof. Background Art

[0002] Hydrogen is considered one of the most promising energy carriers to replace traditional fossil fuels due to its natural abundance, environmental friendliness and high energy density. The storage and transportation of hydrogen are crucial for the industrial application of hydrogen energy. However, the traditional high-pressure gaseous and low-temperature liquid hydrogen has poor storage density and consumes a lot of external energy, which limits the utilization of hydrogen energy. Magnesium hydride, as a typical representative of solid hydrogen storage materials, has attracted much attention due to its high hydrogen storage capacity (7.6wt%), good reversibility and low cost. However, the stable thermodynamics (dehydrogenation temperature exceeds 300℃) and slow hydrogen absorption / desorption kinetics limit the large-scale application of MgH2. People have made great efforts to enhance the thermodynamic and kinetic properties of MgH2, mainly focusing on nano-sizing, alloying and catalyst doping, among which catalyst doping is an effective way to enhance hydrogen storage performance. Metal hydrides have a high catalytic effect on the hydrogen absorption and desorption properties of MgH2. In addition, high-entropy alloy catalysts containing rare earths have shown unique advantages in the fields of hydrogen storage and electrocatalysis, but their preparation process still has significant technical defects.

[0003] Chinese invention patent application CN119680567A discloses a method for preparing rare earth high-entropy alloy catalysts and their applications. During the preparation of these rare earth-containing high-entropy alloy catalysts, the rare earth elements, due to their large differences in atomic radius and melting points, are prone to component segregation during traditional smelting, resulting in uneven distribution of catalytic active sites. High-temperature smelting methods consume extremely high energy, requiring smelting temperatures of 1600-1800°C, which accounts for over 60% of production costs. This also results in larger high-entropy alloy particles, making it difficult to directly generate high-entropy hydride nanoparticles. Summary of the Invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the purpose of the present invention is to provide a high-entropy alloy hydride material with uniform composition and excellent catalytic performance; another purpose of the present invention is to provide a method for preparing a high-entropy alloy hydride material with low cost and simple process; the present invention also provides an application of a high-entropy alloy hydride material as a catalyst in MgH2 hydrogen storage.

[0005] Technical solution: The high entropy alloy hydride material described in the present invention is TiNbVHfZr metal hydride, wherein the content of each metal element Ti, Nb, V, Hf and Zr is 15% to 25% by amount of substance, and the balance is element H.

[0006] Furthermore, the material is in a single-phase state and has a particle size of less than 100 nm.

[0007] The method for preparing the high entropy hydride material comprises the following steps:

[0008] (1) In an argon atmosphere, niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, titanium tetrachloride, and vanadium trichloride are mixed, anhydrous lithium chloride is added, and the mixture is ball-milled;

[0009] (2) Add lithium hydride, ball mill, and pound the sample;

[0010] (3) Repeatedly ultrasonically cleaning and centrifuging the product obtained in step (2) to collect the solid precipitate;

[0011] (4) The solid precipitate obtained in step (3) is vacuum dried and ground to obtain a high entropy alloy hydride material.

[0012] Furthermore, in step (1), the argon atmosphere pressure is less than 0.1 MPa, and the water and oxygen contents are less than 0.1 ppm.

[0013] Furthermore, in step (1), niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, titanium tetrachloride and vanadium trichloride are mixed in a molar ratio of 1:1:1:1:1, and the amount of anhydrous lithium chloride added is 40% to 50% of the total mass of the mixture of niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, titanium tetrachloride and vanadium trichloride.

[0014] Furthermore, the amount of lithium hydride added in step (2) is the same as the total molar amount of chloride ions in niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, vanadium trichloride and titanium tetrachloride added in step (1).

[0015] Furthermore, in step (1), the ball milling is performed for 10 to 14 cycles, the revolution speed of the ball mill is 500 to 550 rpm, the ball-to-material mass ratio is 40 to 45:1, and one mechanical ball milling cycle includes: forward rotation for 30 to 35 minutes, stop rotation for 6 to 8 minutes, reverse rotation for 30 to 35 minutes, and stop rotation for 6 to 8 minutes; in the step (2), the ball milling is performed for 20 to 25 cycles, and the sample is pounded once every 5 cycles of ball milling.

[0016] Furthermore, in step (3), the cleaning solvent is tetrahydrofuran solution, the solvent sample ratio is 1g:70-80mL, and the number of cleanings is 8-10 times; the centrifugation speed is 8000-10000rpm, and the time is 10-15min; in step (4), the room temperature dynamic vacuum drying is performed at a drying temperature of 20-30°C and a drying time of 3-4h. The cleaning is repeated multiple times to remove the lithium chloride impurities added in advance and generated by the reaction.

[0017] The high entropy alloy hydride material described in the present invention is used as a catalyst in MgH2 hydrogen storage.

[0018] Furthermore, the addition amount of the high-entropy alloy hydride material is 5 to 15 wt% by weight. The addition of 5 to 15 wt% improves the dynamic properties of the composite material and maintains an optimized hydrogen storage capacity. When the amount of high-entropy alloy hydride added is greater than 20%, the MgH2 content decreases and the reversible hydrogen release capacity of the composite material decreases significantly.

[0019] Preparation Principle: The preparation principle of high-entropy alloy hydrides relies on precisely controlling the mixing ratio of metal chlorides and hydrides, and then achieving alloying and hydrogenation reactions through ball milling, ultimately forming a high-entropy hydride with a high-entropy effect. The preparation process begins by mixing niobium pentachloride (NbCl5), zirconium tetrachloride (ZrCl4), hafnium tetrachloride (HfCl4), titanium tetrachloride (TiCl4), and vanadium trichloride (VCl3) in molar ratios. The chlorides of Nb, Zr, Hf, Ti, and V are selected for this combination due to their affinity for hydrogen and the multi-electron nature of transition metal atoms, which favors catalysis and the synergistic and multicomponent effects they produce. Lithium chloride is also added at 40% to 50% of the mixture's mass. This step ensures a uniform distribution of all elements in the final alloy. Lithium hydride (LiH) is then added in an amount equal to the total molar amount of chloride ions in the chlorides of niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, vanadium trichloride, and titanium tetrachloride to ensure a sufficient hydrogen source for the subsequent hydrogenation reaction. During the ball milling process, the micro-point high energy generated by high-energy mechanical ball milling impact is used to realize the replacement reduction reaction between lithium hydride (LiH) and metal chloride to generate high-entropy hydride and lithium chloride. The resultant is collected and dispersed in a tetrahydrofuran solution, ultrasonically dispersed and centrifuged to collect the solid precipitate. The above cleaning steps are repeated many times to remove the lithium chloride impurities added in advance and generated by the reaction. High-entropy hydrides have unique advantages in the field of catalysis due to their uniformly mixed multi-metal elements, unique high-entropy effect, rich atomic-level adjustment possibilities and complex surface structure. The ball milling method uniformly compounds high-entropy hydrides with MgH2, significantly improving the hydrogen storage performance of MgH2 and providing an innovative solution for the efficient storage and transportation of hydrogen energy. The chemical reaction equation of the high-entropy hydride prepared in this article is as follows:

[0020] VCl3+TiCl4+NbCl5+HfCl4+ZrCl4+20LiH=TiNbHfVZrH 10 +20LiCl+5H2

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant features:

[0022] 1. High-entropy alloy hydrides exhibit a high-entropy effect due to their uniform mixing of multiple elements, which helps improve the thermal and structural stability of the material, thereby maintaining long-term cyclic stability during hydrogen absorption and desorption;

[0023] 2. The preparation method is simple and efficient. Nanoscale high-entropy alloy hydrides are prepared by a simple ball milling method, which greatly expands the economy and convenience of nano-high-entropy material synthesis;

[0024] 3. High-entropy alloy hydride materials have excellent thermal catalytic properties, which can effectively improve the hydrogen absorption and desorption performance and reversibility of MgH2. The unique high-entropy effect and multi-element catalytic synergistic effect can effectively promote the adsorption and desorption of hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a scanning electron microscope image of the high entropy alloy hydride material prepared by the present invention;

[0026] Figure 2 This is an energy spectrum analysis diagram of the high entropy alloy hydride material prepared by the present invention;

[0027] Figure 3 This is an energy spectrum analysis diagram of the high entropy alloy hydride material prepared by the present invention;

[0028] Figure 4 is an XRD pattern of the high entropy alloy hydride material prepared by the present invention;

[0029] Figure 5 1 is a comparison chart of hydrogen storage performance of high entropy alloy hydride and MgH2 composite materials prepared in Comparative Example 1 and Example 1 of the present invention;

[0030] Figure 6 The hydrogen release curves of the high entropy alloy hydride and MgH2 composite material prepared by the present invention at different ratios are shown.

[0031] Figure 7 is the isothermal hydrogen release curve of MgH2 at different temperatures;

[0032] Figure 8 The isothermal hydrogen release curves of the high entropy alloy hydride and MgH2 composite material prepared by the present invention at different temperatures;

[0033] Figure 9 is the isothermal hydrogen absorption curve of MgH2 at different temperatures;

[0034] Figure 10 These are isothermal hydrogen absorption curves of the high entropy alloy hydride and MgH2 composite material prepared by the present invention at different temperatures. DETAILED DESCRIPTION

[0035] The present invention is further described below with reference to specific embodiments.

[0036] Example 1

[0037] A method for preparing a high entropy alloy hydride material comprises the following steps:

[0038] (1) At room temperature, in an argon atmosphere glove box (oxygen value <0.1 ppm, water value <0.1 ppm, pressure <0.1 MPa), 203 mg of niobium pentachloride, 176 mg of zirconium tetrachloride, 241 mg of hafnium tetrachloride, 143 mg of titanium tetrachloride, and 118 mg of vanadium trichloride were mixed, 400 mg of lithium chloride was added, and the mixture was ball-milled in a stainless steel ball mill with a ball-to-material ratio of 40:1. The ball mill was milled at a revolution speed of 500 rpm for 10 cycles, wherein one cycle consisted of: forward rotation for 30 min, stop for 6 min, reverse rotation for 30 min, and stop for 6 min, to obtain a mixture.

[0039] (2) In the glove box, 120 mg of lithium hydride was added to the ball mill jar. The ball mill was rotated at a speed of 500 rpm for 20 cycles. The sample was pounded once every 4 cycles to prevent the powder from sticking to the wall.

[0040] (3) The obtained sample powder in the ball mill was taken out and dispersed in centrifuge tubes. The mass of the sample powder in each centrifuge tube was 0.5 g. Then 40 ml of tetrahydrofuran solvent was added and ultrasonic oscillation was performed for 10 min to uniformly disperse the powder to obtain a mixed solution. The mixed solution was centrifuged at 8000 rpm for 10 min. The washing step was repeated 8 times to collect the solid precipitate.

[0041] (4) The solid precipitate obtained in step (3) is placed in a dynamic vacuum dryer at room temperature, and the vacuum pump is continuously evacuated for 3 hours. After grinding, a high entropy alloy hydride material with TiNbVHfZr metal elements in an equiatomic ratio is obtained.

[0042] like Figure 1 From the scanning electron microscope image, it can be seen that the high entropy alloy hydride with a particle size of less than 100 nm was prepared by ball milling in this embodiment. Figure 2 , the energy spectrum analysis diagram shows that each metal element in the alloy is evenly dispersed. Figure 3 The energy spectrum analysis diagram from the transmission electron microscope further confirmed the successful preparation of nano-sized high entropy alloy hydride. Figure 4 , XRD confirmed that the prepared composite material was a high entropy alloy hydride, and the alloy was in a single-phase state.

[0043] Example 2

[0044] A method for preparing a high entropy alloy hydride material comprises the following steps:

[0045] (1) At room temperature, in an argon atmosphere glove box (oxygen value <0.1 ppm, water value <0.1 MPa), 250 mg of niobium pentachloride (niobium element molar percentage is 25%), 172 mg of zirconium tetrachloride, 236.8 mg of hafnium tetrachloride, 105.3 mg of titanium tetrachloride (titanium element molar percentage is 15%), and 116.4 mg of vanadium trichloride were mixed, 400 mg of lithium chloride was added, and the mixture was ball-milled in a stainless steel ball mill with a ball-to-material ratio of 45:1. The ball mill was milled at a revolution speed of 550 rpm for 14 cycles, wherein one cycle consisted of: forward rotation for 35 min, stop rotation for 8 min, reverse rotation for 35 min, and stop rotation for 8 min, to obtain a mixture.

[0046] (2) In the glove box, 119 mg of lithium hydride was added to the ball mill jar. The ball mill was rotated at 550 rpm for 25 cycles. The sample was pounded once every 5 cycles to prevent the powder from sticking to the wall.

[0047] (3) The obtained sample powder was taken out from the ball mill and dispersed in a centrifuge tube. The mass of the sample powder in each centrifuge tube was 0.5 g. Then 40 ml of tetrahydrofuran solvent was added and ultrasonic vibration was performed for 10 minutes to uniformly disperse the powder to obtain a mixed solution. The mixed solution was centrifuged at 10,000 rpm for 15 minutes. The washing step was repeated 10 times and the solid precipitate was collected.

[0048] (4) The solid precipitate obtained in step (3) is placed in a dynamic vacuum dryer at room temperature, and the vacuum pump is continuously evacuated for 4 hours. After grinding, a high entropy alloy hydride material is obtained, in which the metal elements are uniformly dispersed and the alloy is in a single-phase state.

[0049] Comparative Example 1

[0050] Unlike Example 1, a high-entropy alloy prepared by a high-temperature smelting method is used to replace metal chloride to prepare a high-entropy alloy hydride, wherein the alloy is an equimolar high-entropy alloy, and the molar percentage of each metal element is 20%. Specifically, the following steps are included:

[0051] (1) 5 g of Ti, Nb, V, Hf, and Zr metal powders were prepared in a molar ratio of 1:1:1:1:1. The mixture was mechanically ball-milled for 2 h and then subjected to magnetic levitation melting under argon protection to form a melt. After cooling, a TiNbVHfZr high-entropy alloy ingot was obtained, which was then mechanically crushed to obtain a bulk TiNbVHfZr high-entropy alloy.

[0052] (2) In a glove box, take 1 g of bulk TiNbVHfZr high-entropy alloy and place it in a hydrogen absorption and desorption test device. Evacuate the device, check for leaks, and fill it with hydrogen to a pressure of approximately 30 bar. Heat the device to 500°C at a heating rate of 5°C / min and hold for 1 hour. Repeat this process five times to obtain a powdered TiNbVHfZr high-entropy alloy.

[0053] (3) At room temperature, in an argon atmosphere glove box (oxygen value <0.1 ppm, water value <0.1 ppm, pressure <0.1 MPa), 880 mg of TiNbVHfZr prepared by the high-temperature smelting method was mixed with 400 mg of lithium chloride and ball-milled in a stainless steel ball mill with a ball-to-material ratio of 40:1. The ball mill was milled at a revolution speed of 500 rpm for 10 cycles, each cycle consisting of: forward rotation for 30 minutes, stop for 6 minutes, reverse rotation for 30 minutes, and stop for 6 minutes to obtain a mixture. The remaining steps were the same as in Example 1 to obtain a high-entropy alloy hydride.

[0054] like Figure 5 As shown, the high entropy alloy hydride prepared by the method of the present invention has a significantly better effect on improving the hydrogen storage performance of MgH2 than the high entropy alloy hydride prepared in Comparative Example 1.

[0055] Application Example 1

[0056] The effects of different doping ratios of the high entropy alloy hydride material prepared in Example 1 on the heating and hydrogen release performance of MgH2 were studied.

[0057] (1) Prepare MgH2+mwt% high entropy alloy hydride composite samples (m=5 / 10 / 15), take 50 / 100 / 150 mg of nano high entropy alloy hydride and add 950 / 900 / 850 mg of MgH2 into a stainless steel ball mill in an argon atmosphere glove box, and ball mill the mixture with a ball-to-material ratio of 40:1. The ball mill revolution speed is 400 rpm, and the milling is repeated for 6 cycles. The sample is pounded once in 3 cycles to prevent the wall powder from sticking. One cycle includes: forward rotation for 30 min, stop for 6 min, reverse rotation for 30 min, and stop for 6 min, to obtain 3 composite samples.

[0058] (2) Take 120-150 mg of each of the three samples from the glove box, place them in a hydrogen absorption and desorption test device, evacuate the device, check for leaks, and heat it to 450°C at a heating rate of 5°C / min.

[0059] like Figure 6 As shown, the 10wt% composite material significantly improves the performance of MgH2 and can maintain the hydrogen content of the composite material to a large extent, which can significantly improve the heating and hydrogen release effect of MgH2.

[0060] Application Example 2

[0061] The effect of the high entropy alloy hydride prepared in Example 1 on the hydrogen desorption performance of MgH2 at different temperatures was studied.

[0062] (1) In a glove box, four portions of 120-150 mg of MgH2+10 wt% high entropy alloy hydride were taken and placed in a hydrogen absorption and desorption test device respectively. The device was evacuated, leak tested, and filled with a hydrogen pressure of about 30 bar. The temperature was raised to 250°C, 260°C, 275°C, and 300°C at a heating rate of 5°C / min and kept warm for 1 h.

[0063] (2) Take four portions of 120-150 mg of MgH2 from the glove box and place them in Sievert's apparatus respectively. Evacuate the air, check for leaks, fill with hydrogen pressure of about 30 bar, and heat at a rate of 5°C / min to 385°C, 370°C, 355°C and 340°C and keep them warm for 1 h.

[0064] like Figure 7 and Figure 8 As shown in the isothermal hydrogen desorption curves at different temperatures, the prepared high entropy alloy hydride material is an efficient catalyst, which significantly enhances the hydrogen desorption performance of MgH2. It basically completes hydrogen desorption within 4 minutes at 275°C, while pure MgH2 requires nearly 15 minutes to complete complete hydrogen desorption at 355°C.

[0065] Application Example 3

[0066] The effect of the high entropy alloy hydride material prepared in Example 1 on the hydrogen absorption performance of MgH2 at different temperatures was studied.

[0067] (1) Take four portions of 120-150 mg of MgH2+10 wt% high entropy alloy hydride from the glove box and place them in the hydrogen absorption and desorption test device respectively. Evacuate the device, check for leaks, fill it with hydrogen pressure of about 30 bar, and heat it to 100℃, 125℃, 150℃ and 175℃ at a heating rate of 5℃ / min and keep it warm for 1 h.

[0068] (2) Take four portions of 120-150 mg of MgH2 from the glove box and place them in Sievert's apparatus respectively. Evacuate the apparatus, check for leaks, fill it with hydrogen pressure of about 30 bar, and heat it to 200℃, 225℃, 250℃ and 275℃ at a heating rate of 5℃ / min and keep it warm for 1 h.

[0069] like Figure 9 and Figure 10 As shown in the isothermal hydrogen absorption curves at different temperatures, the incorporation of the prepared high-entropy alloy hydride material exhibits faster hydrogen absorption kinetics. Specifically, pure MgH2 absorbs 6.6wt% of hydrogen in 11 minutes at a high temperature of 275°C. In contrast, the incorporation of the high-entropy alloy hydride can absorb 5.6wt% of hydrogen in 5 minutes at 150°C, demonstrating extremely fast hydrogen absorption kinetics.

Claims

1. A high entropy alloy hydride material, characterized in that: It is TiNbVHfZr metal hydride, wherein the contents of each metal element Ti, Nb, V, Hf and Zr are 15% to 25% by amount of substance, and the balance is element H.

2. The high entropy alloy hydride material according to claim 1, characterized in that: The material is in a single-phase state and the particle size is less than 100nm.

3. A method for preparing a high entropy alloy hydride material according to claim 1, characterized in that: The following steps are involved: (1) In an argon atmosphere, niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, titanium tetrachloride and vanadium trichloride are mixed in proportion, anhydrous lithium chloride is added, and the mixture is ball-milled; (2) Add lithium hydride, ball mill, and pound the sample; (3) Repeatedly ultrasonically cleaning and centrifuging the product obtained in step (2) to collect the solid precipitate; (4) The solid precipitate obtained in step (3) is vacuum dried and ground to obtain a high entropy alloy hydride material.

4. The method for preparing a high entropy alloy hydride material according to claim 3, wherein: In the step (1), the argon atmosphere pressure is less than 0.1 MPa, and the water and oxygen contents are less than 0.1 ppm.

5. The method for preparing a high entropy alloy hydride material according to claim 3, wherein: In the step (1), niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, titanium tetrachloride and vanadium trichloride are mixed in a molar ratio of 1:1:1:1:1, and the amount of anhydrous lithium chloride added is 40% to 50% of the total mass of the mixture of niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, titanium tetrachloride and vanadium trichloride.

6. The method for preparing a high entropy alloy hydride material according to claim 3, wherein: The amount of lithium hydride added in step (2) is the same as the total molar amount of chloride ions in niobium pentachloride, zirconium tetrachloride, hafnium tetrachloride, vanadium trichloride and titanium tetrachloride added in step (1).

7. The method for preparing a high entropy alloy hydride material according to claim 3, wherein: In the step (1), the ball milling is performed for 10 to 14 cycles, the revolution speed of the ball mill is 500 to 550 rpm, the ball-to-material mass ratio is 40 to 45:1, and one mechanical ball milling cycle includes: forward rotation for 30 to 35 minutes, stop rotation for 6 to 8 minutes, reverse rotation for 30 to 35 minutes, and stop rotation for 6 to 8 minutes; in the step (2), the ball milling is performed for 20 to 25 cycles, and the sample is pounded once every 5 cycles of ball milling.

8. The method for preparing a high entropy alloy hydride material according to claim 3, wherein: In the step (3), the cleaning solvent is tetrahydrofuran solution, the solvent sample ratio is 1g:70-80mL, and the number of cleaning times is 8-10 times; the centrifugal speed is 8000-10000rpm, and the time is 10-15min; in the step (4), the room temperature dynamic vacuum drying is performed, the drying temperature is 20-30°C, and the drying time is 3-4h.

9. Use of the high entropy alloy hydride material according to claim 1 as a catalyst in MgH2 hydrogen storage.

10. Use of the high entropy alloy hydride material according to claim 9 as a catalyst in MgH2 hydrogen storage, characterized in that: The addition amount of the high entropy alloy hydride material is 5 to 15 wt % by weight.

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