An activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material and its preparation method
The TiFeMnCo alloy catalyst was prepared by smelting and composited with MgH2, and Mn and Co elements were added, which solved the problems of long preparation time and activation requirement in the existing technology, and achieved simplified preparation and excellent performance of high-efficiency hydrogen storage materials.
Patent Information
- Application Number
- CN202311354491.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-19
- Publication Date
- 2025-09-05
- Estimated Expiration
- 2043-10-19
AI Technical Summary
The existing technology for preparing hydrogen storage alloy catalysts has the problems of time-consuming preparation methods, complicated processes and the need for activation operations. In particular, the defects of the ball milling method and the smelting method have failed to effectively solve the problem of preparing high-efficiency hydrogen storage materials.
The TiFeMnCo alloy catalyst was prepared by a smelting method and composited with MgH2. By adding Mn and Co elements and utilizing their synergistic effect, efficient hydrogen storage performance without activation was achieved, simplifying the preparation process.
The preparation of high-efficiency hydrogen storage materials is achieved, the preparation time is shortened, the production cost is reduced, the hydrogen storage kinetics performance is improved, the catalytic effect is enhanced, and no activation operation is required.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of hydrogen storage materials, and particularly relates to an activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material and a preparation method thereof. Background Art
[0002] Among metal hydrogen storage materials, magnesium has the characteristics of high hydrogen storage capacity of up to 7.6wt.%, abundant resources, environmental protection, and low cost. However, when used as a hydrogen storage material, Mg has problems such as slow hydrogen absorption and desorption rate, poor kinetic performance, stable hydride, and high hydrogen desorption temperature. Exploring efficient hydrogenation reaction strategies, increasing hydrogen absorption and desorption rates, and reducing hydrogen absorption and desorption temperatures have become the core issues of current research. Doping metal compounds to prepare composite materials can effectively improve the hydrogen absorption and desorption kinetics of magnesium-based materials.
[0003] There are two main methods for preparing doped metal compounds: smelting method and mechanical ball milling method.
[0004] Mechanical ball milling, also known as ball milling, is a new technology that, in addition to requiring no heating, offers significant advantages for preparing alloys with widely varying melting points and those that are difficult to smelt. Furthermore, in the context of the alloy catalysts described herein, ball milling also produces a powdered product, eliminating the need for activation.
[0005] For example, existing document 1 ("Hydriding properties of mechanical alloys Mg Ni" Journal of the Less Common Metals, 1987, 131:89-97) uses mechanical ball milling to prepare Mg2Ni. The results show that the alloy prepared by this method is easier to activate than alloys prepared by smelting, resulting in a better catalytic effect. This document demonstrates that the ease of activation of the metal compound added as a catalyst directly affects the improvement in the material's hydrogen storage properties.
[0006] For example, the existing literature 2 (Hydrogen storage properties of Mg-doped Ti 1.2 Fe alloyssynthesized by mechanical alloying,Transactions of Nonferrous Metals Society of China,2003,02:249-253) and literature 3(Ti 1.2Hydrogen Storage Properties of Fe+x%Mg (x=1, 3, 5) Alloys, Rare Metal Materials and Engineering, 2003, 03:220-223. TiFe was prepared using both smelting and mechanical ball milling. This paper concludes that even after complete activation through repeated hydrogen absorption and desorption cycles at 450°C and 3 MPa of hydrogen pressure, the TiFe alloy prepared by smelting still does not achieve the same performance as that obtained by ball milling, demonstrating that ball milling is superior to smelting.
[0007] Therefore, combined with the content of existing document 4 ("Overview of Research on the Application of Hydrogen Storage Materials in Catalytic Hydrogenation and Dehydrogenation Reactions," Materials Review, 1994, 05:20-24), it can be confirmed that there is a consensus in the field of hydrogen storage alloys to which the present invention relates: mechanical ball milling is a preferred method for preparing doped hydrogen storage alloy catalysts. However, this method has the following two technical issues: 1. Long milling cycles; 2. Complicated process.
[0008] For example, in existing document 5 (《The effect of different Co phase structure (FCC / HCP) on the catalytic action towards the hydrogen storage performance of MgH2》, Chinese Journal of Chemical Engineering, 2022, 43: 343-352), since ball milling was used to prepare the catalyst, ball milling was also used in the subsequent composite process, that is, a secondary ball milling method was used to prepare a Co-MgH2 composite material. Although MgH2 + 7% wt.% FCC Co can achieve 6.5 wt.% hydrogen release at 325 ° C for 10 min, and the initial hydrogen release temperature is reduced from 301.3 ° C to 195.0 ° C. However, in its preparation method, the total time for only two ball milling processes has reached 50 h, and together with the subsequent steps, the entire preparation process takes more than 70 h. The document shows that the ball milling method has technical problems such as time-consuming and cumbersome process.
[0009] In order to solve the problem that the above-mentioned preparation method is time-consuming, a feasible method is to prepare the alloy catalyst by smelting method and then compound it by ball milling method, that is, to prepare the alloy catalyst by smelting method instead of ball milling method. This type of preparation method only uses one ball milling, which can effectively reduce the time of the entire preparation method. However, as a traditional preparation method, although the smelting method has the advantages of simple process and maturity, the most significant technical problem of the smelting method in the field of alloy catalysts of the present invention is that the obtained alloy is in a cast state, and in the process of crushing and compounding with hydrogen storage materials, it is also necessary to cooperate with activation operation to achieve the technical effect of improving hydrogen storage performance. In other words, the currently common alloy catalysts cannot achieve good catalytic effects without activation treatment.
[0010] For example, existing document 6 ("Synthesis by high-energy ball milling of MgH2-TiFe composites for hydrogen storage", Materials Science Forum, 2017, 899:13-18) prepares a MgH2-TiFe material that can absorb 3.5 wt.% hydrogen at room temperature, but the hydrogen absorption rate is very slow, requiring 13 hours. The TiFe alloy catalyst prepared by this technical solution is doped without activation, and therefore has a poor effect on the kinetic modification of MgH2 hydrogen absorption and desorption.
[0011] In contrast, the existing literature7 (《Ti 1.2 "Hydrogen Storage Properties of Fe+x%Mg (x=1, 3, 5) Alloys," Rare Metal Materials and Engineering, 2003, 32:220-223. This technical solution involves preparing the material by smelting. The sample is then exposed to a 2MPa hydrogen pressure at 350°C for 1 hour at an activation temperature of 350-430°C. After continuous vacuuming, the hydrogen is replenished to 2MPa and maintained for 30 minutes to achieve a single activation process for the TiFe alloy. This technical solution successfully improves catalytic performance by activating the alloy catalyst. However, this activation process introduces new technical challenges: a single activation cycle takes two hours, and according to the documented results, some samples fail to absorb hydrogen through a single activation, requiring repeated activation cycles until the TiFe alloy is fully activated.
[0012] In order to reduce the increase in process steps and preparation time caused by the separate activation operation, the main inventors of the present invention integrated the activation operation into the preparation process of the alloy catalyst in the early stage of the preparation process.
[0013] For example, existing document 8 ("Mechanical Chemical Preparation of Mg-Ni-Ti 0.32 Cr0.35 V 0.07 Fe 0.26 Hydrogen storage and decomposition properties of composite materials, Rare Metal Materials and Engineering, 2007, 09: 1672-1676), Ti was prepared by vacuum non-consumable arc furnace melting method. 0.32 Cr 0.35 V 0.07 Fe 0.26 , and then Mg, Ni and the alloy are ball-milled together under a hydrogen pressure of 5MPa to obtain a composite hydrogen storage material. The "hydrogen pressure ball milling" in this technical solution is to combine the two steps of activation operation and composite ball milling. Although this method replaces the ball milling method with the smelting method to prepare the alloy, in order to achieve the activation effect, high hydrogen pressure conditions are adopted in the composite ball milling process, which simplifies the preparation steps and saves preparation time. At the same time, the high hydrogen pressure conditions inevitably introduce new technical problems - higher gas pressures inevitably pose safety hazards, and although the separate activation processes have been reduced and merged, the preparation process still has an activation link.
[0014] Similarly, another previous work of the main inventor of the present invention, existing document 9 ("Mg-Ni-Ti 19 Cr 50 V 22 The study on the structure and hydrogenation kinetics of Mn9, Rare Metal Materials and Engineering, 2006, 35: 1859-1863) also adopts a similar preparation method to prepare the material. When obtaining higher hydrogen storage performance, the above technical problems also exist.
[0015] Based on the above problems and the recent research results of the inventors, the preparation of alloy catalysts that do not require activation is a method to solve the above problems from the root. Summary of the Invention
[0016] The present invention aims to provide an activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material and its preparation method. This approach addresses the existing technical challenges by replacing ball milling with a smelting method to prepare the alloy catalyst. Furthermore, by adding other elements, adjusting the composition ratio, and adjusting the preparation process, the composite material's hydrogen storage performance is guaranteed. Specifically, the material maintains hydrogen storage capacity, reduces hydrogen desorption temperature, and improves kinetic performance, while addressing the complex and time-consuming preparation process.
[0017] In order to achieve the above-mentioned object of the invention, the present invention adopts the following inventive concept:
[0018] In order to increase the hydrogen storage capacity of the material, Mn is added. At the same time, in order to reduce the initial hydrogen desorption temperature and improve the kinetic properties, Co is added. Its unique structure forms a transition state intermediate with H, thereby reducing the stability of the Mg-H bond in MgH2, allowing it to desorb hydrogen rapidly.
[0019] At the same time, the synergistic effect between Mn and Co elements is utilized to achieve catalytic performance of TiFe alloy without activation.
[0020] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:
[0021] An activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material is prepared by composite ball milling of TiFeMnCo and MgH2, and the size of the composite hydrogen storage material is 1-6 μm; wherein MgH2 is a matrix material, and TiFeMnCo is uniformly distributed on the surface of MgH2; the TiFeMnCo is prepared by a smelting method; and contains MgH2 phase and TiFe 0.92 Mn 0.04 Co 0.04 phase and a small amount of α-Fe phase, among which the content of MgH2 phase is 82%-84%, TiFe 0.92 Mn 0.04 Co 0.04 The content of the phase is 11%-13%, and the content of the α-Fe phase is 5%-6%.
[0022] A method for preparing an activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material comprises the following steps:
[0023] Step 1, melting the TiFeMnCo ingot, first, to meet a certain alloy component atomic percentage, titanium block, iron block, cobalt block, and manganese block are subjected to high-frequency magnetic levitation melting under certain conditions, after the melting is completed, the ingot is cooled to room temperature using a water-cooled copper crucible to obtain a TiFeMnCo ingot;
[0024] In step 1, the alloy composition atomic percentage of the TiFeMnCo ingot is 50 at.%, 46 at.%, 2 at.%, and 2 at.% of Mn. The obtained alloy is TiFe 0.92 Mn 0.04 Co 0.04 alloy;
[0025] In step 1, the smelting power of the high-frequency magnetic levitation smelting is 25-30kW;
[0026] Step 2, refining the TiFeMnCo ingot, refining the TiFeMnCo ingot obtained in step 1 to obtain TiFeMnCo powder;
[0027] In step 2, the conditions for refinement are: first mechanically crushing, and then screening with a sieve of 2000 mesh;
[0028] Step 3, preparation of magnesium hydride-TiFeMnCo composite hydrogen storage material based on smelting method, after mixing TiFeMnCo powder and MgH2, composite ball milling is performed under certain conditions to obtain magnesium hydride-TiFeMnCo composite hydrogen storage material based on smelting method, referred to as MgH2-TiFeMnCo;
[0029] In step 3, the TiFeMnCo powder accounts for 10 wt.% of the total mass of the composite hydrogen storage material;
[0030] In step 3, the conditions for composite ball milling are as follows: under argon conditions, stainless steel balls are used as grinding beads, the ball-to-material ratio is 35-40:1, the ball milling speed is 230-250 rpm, and the ball milling method is forward and reverse intermittent ball milling, specifically, the ball milling time is 30 minutes, the pause time is 10 minutes, and then reverse ball milling, and the total ball milling time is 38-42 hours.
[0031] An activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material is used as a hydrogen storage material. At 250°C and 3MPa, the maximum hydrogen absorption capacity can reach 4.8wt.%. Under vacuum conditions at 250°C, 70% of the maximum hydrogen release capacity can be reached in 9s, and hydrogen can be released at 220°C.
[0032] The technical effects of the present invention are as follows after experimental detection:
[0033] XRD test results of magnesium hydride-TiFeMnCo composite hydrogen storage material show that it contains MgH2 phase and TiFe 0.92 Mn 0.04 Co 0.04 phase and a small amount of α-Fe phase. The content of MgH2 phase was 82%-84% and TiFe 0.92 Mn 0.04 Co 0.04 The content of the phase is 11%-13%, and the content of the α-Fe phase is 5%-6%.
[0034] SEM test results show that the average particle size of the magnesium hydride-TiFeMnCo composite hydrogen storage material is 1-6μm, with small particles agglomerated and evenly dispersed. EDS test results show that the TiFeMnCo and MgH2 composite material has a high degree of composite.
[0035] The results of hydrogen absorption kinetics test show that at 250°C and 3 MPa, the maximum hydrogen absorption capacity is 4.8 wt.%, and the time required to reach 70% of the maximum hydrogen absorption capacity is about 9 s;
[0036] The results of hydrogen desorption kinetics test show that under vacuum conditions at 250°C, the amount of hydrogen desorption reaches 4.3wt.% in 1000s.
[0037] Compared with the prior art, the present invention has the following advantages:
[0038] 1. The present invention prepares magnesium hydride-TiFeMnCo composite hydrogen storage material based on smelting method and ball milling method. The smelting method is used instead of the ball milling method to prepare TiFeMnCo, which simplifies the preparation process, greatly saves time, reduces production costs, and realizes the preparation of high-performance hydrogen storage materials.
[0039] 2. Compared with the prior art, the present invention has more excellent hydrogen storage kinetics. Compared with Comparative Example 1, the hydrogen absorption amount increased by 17.6% and the hydrogen desorption amount increased by 340% under the same hydrogen absorption and desorption time. At the same time, it has a lower hydrogen desorption temperature (220°C), which is 30% lower than that of Comparative Example 1.
[0040] 3. Compared with the prior art, the present invention is prepared by a smelting method and Mn and Co elements are added, thereby achieving the effect of improving the activation performance, so that the prepared magnesium hydride-TiFeMnCo composite hydrogen storage material can absorb and release hydrogen without activation, and TiFeMnCo has a better catalytic effect and excellent hydrogen storage performance. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Figure 1 This is an SEM image of TiFeMnCo prepared in step 2 of Example 1;
[0042] Figure 2 The XRD pattern of the #1-10TiFeMnCo composite material prepared in step 3 of Example 1;
[0043] Figure 3 The SEM image and EDS surface scanning image of the #1-10TiFeMnCo composite material prepared in Example 1 at a scale length of 5 μm;
[0044] Figure 4 The isothermal hydrogen absorption curves of different materials at 250° C. for Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5 of the present invention are shown;
[0045] Figure 5 The isothermal hydrogen release curves of different materials at 250° C. for Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5 of the present invention are shown;
[0046] Figure 6The XRD patterns of the TiFeMnCo composite material prepared by ball milling in Comparative Example 2 and the TiFeMnCo composite material prepared in step 2 of Example 1 are shown. DETAILED DESCRIPTION
[0047] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The embodiments described in this patent are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the absence of conflict, the features in the following embodiments can be combined with each other.
[0048] Example 1
[0049] A method for preparing an activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material comprises the following steps:
[0050] Step 1, melting of TiFeMnCo ingot, first, with the alloy composition atomic percentage of Ti content of 50at.%, Fe content of 46at.%, Mn content of 2at.%, Co content of 2at.%, titanium block, iron block, cobalt block, manganese block under the condition of melting power of 28kW, after melting, use water-cooled copper crucible to cool to room temperature, and TiFe 0.92 Mn 0.04 Co 0.04 Ingots of alloys, wherein TiFe 0.92 Mn 0.04 Co 0.04 The alloy is referred to as TiFeMnCo, TiFe 0.92 Mn 0.04 Co 0.04 The ingot of the alloy is referred to as TiFeMnCo ingot;
[0051] Step 2, refinement of TiFeMnCo ingot, mechanically crushing the TiFeMnCo ingot obtained in step 1, and then sieving it with a 2000 mesh screen to achieve refinement, and then TiFe 0.92 Mn 0.04 Co 0.04 Alloy powder, referred to as TiFeMnCo powder;
[0052] In order to prove the refinement effect of step 2 on TiFeMnCo, SEM test was carried out. The test results are as follows Figure 1 As shown, the particle size of the TiFeMnCo powder is 4-6 μm.
[0053] Step 3, preparation of magnesium hydride-TiFeMnCo composite hydrogen storage material based on the smelting method, the TiFeMnCo powder obtained in step 2 accounts for 10 wt.% of the total mass of the composite hydrogen storage material, the TiFeMnCo powder and MgH2 are mixed, and under argon conditions, stainless steel balls are used as grinding beads, the ball-to-material ratio is 40:1, the ball milling speed is 240 rpm, and the ball milling method is forward and reverse intermittent ball milling, specifically, the ball milling time is 30 minutes, the pause time is 10 minutes, and then the reverse ball milling is performed. The total ball milling time is 40 hours. Composite ball milling is performed to obtain an activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material, abbreviated as MgH2-TiFeMnCo, wherein the MgH2-TiFeMnCo obtained in Example 1 is named #1-10TiFeMnCo.
[0054] In order to verify the phase types and mass fractions of #1-10TiFeMnCo, as well as the phase changes during the preparation process, the obtained #1-10TiFeMnCo was subjected to XRD test and Rietveld method refinement.
[0055] XRD test results are as follows Figure 2 As shown, #1-10TiFeMnCo contains MgH2 phase and TiFe 0.92 Mn 0.04 Co 0.04 phase and a small amount of α-Fe phase;
[0056] The results of the Rietveld method refinement show that the content of MgH2 phase in #1-10TiFeMnCo is 83.2%, and the content of TiFe 0.92 Mn 0.04 Co 0.04 The content of the Si phase is 11.7%, and the content of the α-Fe phase is 5.1%.
[0057] In order to further verify the microstructure and phase distribution of #1-10TiFeMnCo, SEM test and EDS test were carried out. The test results are as follows Figure 3 As shown, the test results show that the average particle size of #1-10TiFeMnCo is 1-3μm, showing small particle agglomeration and uniform dispersion. The test results show that the TiFeMnCo and MgH2 composite degree in #1-10TiFeMnCo is high.
[0058] In order to demonstrate the hydrogen storage performance of #1-10TiFeMnCo, hydrogen absorption and desorption kinetics tests were carried out.
[0059] The results of hydrogen absorption kinetics test are as follows Figure 4 As shown in Table 1, at 250 °C and 3 MPa, the maximum hydrogen absorption capacity can reach 4.8 wt.%, and 70% of the maximum hydrogen release capacity can be achieved in 9 s;
[0060] The results of hydrogen release kinetics test are as follows Figure 5 As shown in Table 1, under vacuum conditions at 250°C, the amount of hydrogen released in 1000s is 4.3 wt.%, and hydrogen can be released at 220°C.
[0061] Table 1 Summary of hydrogen absorption and desorption kinetics of all composite hydrogen storage materials in this patent at 250°C
[0062]
[0063] In order to prove the effect of activation treatment on performance, that is, the technical effect of activation-free in the technical solution of the present invention, the existing literature is cited for comparison. Some information of the existing literature is shown in Table 2.
[0064] According to existing document 2-1, after the TiFeMnCo is prepared by the smelting method, an additional independent activation treatment process is required, referred to as independent activation treatment. In addition, even after the activation treatment, the hydrogen storage performance obtained is still lower than that of the present invention.
[0065] According to existing document 2-2, this technical solution uses a Mg-ZrFeCr hydrogen storage material prepared by a smelting method and ball milling method similar to the preparation method of the present invention. Like existing document 2-2, it also requires independent activation treatment. Moreover, even after the activation treatment, the hydrogen storage performance obtained is still lower than that of the present invention.
[0066] According to existing documents 2-3, this technical solution adopts the same method as existing documents 8 and existing documents 9 mentioned in the background technology. In the ball milling method after the smelting method, a method is adopted under high hydrogen pressure conditions without the need for independent activation treatment, which is referred to as synchronous activation treatment; even after the activation treatment, the hydrogen storage performance obtained is still lower than that of the present invention.
[0067] Table 2 Summary of preparation methods and activation properties of other system materials
[0068]
[0069]
[0070] 2-1. HQQu, JLDu, CHPu, et al. Effects of Co introduction on hydrogenstorage properties of Ti-Fe-Mn alloys. International Journal of HydrogenEnergy. 2015, 40: 2729-2735.
[0071] 2-2. R. Florianoa, DR Leivab, J. Dessib, et al. Mg-based Nanocomposites for Hydrogen Storage Containing Ti-Cr-V Alloys as Additives. Materials Research. 2016, 19: 80-85.
[0072] 2-3. P.Wang, HFZhang, BZDing, et al. Structural and hydridingproperties of composite Mg-ZrFe 1.4 Cr 0.6 .Acta materialia.2001,49:921-926.
[0073] To further demonstrate the performance of the present invention, we cite existing literature on TiFe-based hydrogen storage materials for comparison. Table 3 shows some information from these existing literature. All materials require activation treatment, and regardless of whether they are activated independently or simultaneously, their hydrogen storage performance is inferior to that of the present invention.
[0074] Table 3 Summary of preparation methods and activation properties of Mg / MgH2-TiFe system materials
[0075]
[0076] 3-1. CSZhou, ZZFang, C.Ren, et al. Effect of Ti Intermetallic Catalysts on Hydrogen Storage Properties of Magnesium Hydride. The JournaL of Physical Chemistry, 2013, 117: 12973-12980.
[0077] 3-2. C.Lal, IPJain. Effect of ball milling on structural and hydrogenstorage properties of Mg-x wt% FeTi (x=2&5) solid solutions International Journal of Hydrogen Energy, 2012, 37(4): 3761-3766.
[0078] 3-3. RASilva, RMLeal, et al. Room temperature hydrogen absorption byMg and Mg-TiFe nanocomposites processed by high-energy ballmilling. International Journal of Hydrogen Energy, 43(27):12251-12259.
[0079] 3-4. T. Kondo, K. Shindo1, Y. Sakurai. Dependence of hydrogen storage characteristics of Mg-TiFe 0.92 Mn 0.08 composite on amount of TiFe 0.92 Mn 0.08 .Journal of Alloys and Compounds.2005,404-406:511-514.
[0080] In order to demonstrate the effect of TiFeMnCo on hydrogen storage materials, Comparative Example 1 is provided, in which pure ball-milled MgH2 without adding TiFeMnCo is used as a basic comparative example.
[0081] Comparative Example 1
[0082] A hydrogen storage material without alloy powder added, wherein the steps not specifically stated are the same as those in Example 1, except that steps 1 and 2 are not performed, and only step 3 is performed, and in step 3, the TiFeMnCo powder accounts for 0 wt.% of the total mass of the composite hydrogen storage material, i.e., no TiFeMnCo powder is added, and the obtained material is named #0-MgH2.
[0083] In order to demonstrate the hydrogen storage performance of #0-MgH2, hydrogen absorption and desorption kinetics tests were carried out.
[0084] The results of hydrogen absorption kinetics test are as follows Figure 4 As shown, at 250 °C and 3 MPa, the maximum hydrogen absorption capacity is 5.7 wt.%, and the time required to reach 70% of the maximum hydrogen absorption capacity is about 9 s;
[0085] The results of hydrogen release kinetics test are as follows Figure 5 As shown, under vacuum conditions at 250°C, the amount of hydrogen released in 1000s is only 1.10wt.%.
[0086] Comparison of the hydrogen absorption and desorption test results with those of Example 1 shows that when TiFeMnCo powder is added to MgH2, the hydrogen absorption and desorption rates of the hydrogen storage material are improved, and the minimum hydrogen desorption temperature can be reduced to 220°C.
[0087] The reason is that TiFeMnCo is evenly distributed on the Mg surface, and the following technical effects are obtained during the ball milling process:
[0088] 1. Generate new active nucleation sites;
[0089] 2. Reduce particle size and form more interfaces. The existence of interfaces provides more diffusion channels for hydrogen release;
[0090] 3. The production of new α-Fe phase is beneficial to improving the dissociation of hydrogen molecules and the diffusion of hydrogen atoms.
[0091] In order to demonstrate the influence of the TiFeMnCo powder obtained by the preparation process on the composite hydrogen storage material, Comparative Example 2 is provided, which is a magnesium hydride-TiFeMnCo composite hydrogen storage material based on the ball milling method.
[0092] Comparative Example 2
[0093] A method for preparing a magnesium hydride-TiFeMnCo composite hydrogen storage material based on a secondary ball milling method. The steps not specifically described are the same as those in Example 1, except that: Steps 1 and 2, the smelting and refinement of the TiFeMnCo ingot are not performed, and instead a ball milling method is used instead of a smelting method. The magnesium hydride-TiFeMnCo composite hydrogen storage material obtained by the ball milling method is referred to as #3-TiFeMnCo.
[0094] The specific conditions of the ball milling method are as follows: with the same atomic percentage of alloy components as in Example 1, titanium blocks, iron blocks, cobalt blocks, and manganese blocks are milled under argon conditions with stainless steel balls as grinding beads, a ball-to-material ratio of 10:1, a ball milling speed of 240 rpm, and a forward and reverse intermittent ball milling method, specifically, a ball milling time of 30 minutes, a pause time of 10 minutes, and then reverse ball milling, and a total ball milling time of 10 hours.
[0095] In order to prove the phase type of TiFeMnCo, XRD test was carried out. The test results are as follows Figure 6 As shown, the TiFeMnCo prepared by ball milling has 0.92 Mn 0.04 Co 0.04 The XRD test results are compared with those in Example 1. It can be seen that the TiFeMnCo powder obtained by smelting only has TiFe 0.92 Mn 0.04 Co 0.04Phase, while the TiFeMnCo powder obtained by ball milling has many impurity peaks. The test results show that the TiFeMnCo powders prepared by smelting and ball milling have different phase compositions.
[0096] In order to demonstrate the hydrogen storage performance of #3-TiFeMnCo, hydrogen absorption and desorption kinetics tests were carried out.
[0097] The results of hydrogen absorption kinetics test are as follows Figure 4 As shown, at 250 °C and 3 MPa, the maximum hydrogen absorption capacity is 3.6 wt.%, and it takes 14 s to reach 70% of the maximum hydrogen absorption capacity;
[0098] The results of hydrogen release kinetics test are as follows Figure 5 As shown, under vacuum conditions at 250°C, the amount of hydrogen released in 1000s is only 1.10wt.%.
[0099] Comparison of the hydrogen absorption and desorption test results with those of Example 1 shows that adding TiFeMnCo powder prepared by smelting method to MgH2 has a better effect on improving the maximum hydrogen absorption and desorption capacity and hydrogen absorption and desorption rate of the hydrogen storage material than TiFeMnCo powder prepared by ball milling method.
[0100] Combined with the XRD test results, it can be seen that the difference in hydrogen absorption and desorption kinetics is due to the different phase compositions of TiFeMnCo powders prepared by the smelting method and the ball milling method. In addition, the smelting method also achieved the following technical effects:
[0101] 1. Only TiFe exists 0.92 Mn 0.04 Co 0.04 Phase, which provides an interface on the Mg matrix and an effective channel for hydrogen diffusion;
[0102] 2. The phase distribution of the sample after smelting is more uniform, shortening the hydrogen diffusion path.
[0103] In order to demonstrate the role of each element in the composite hydrogen storage material, that is, the influence of the alloy composition on the composite hydrogen storage material, comparative examples 3 and 4 are provided, in which the alloy composition is a ternary alloy TiFeMn alloy and a TiFeCo alloy; in addition, comparative example 5 is also provided for comparison, in which the alloy composition is a binary alloy TiFe alloy.
[0104] Comparative Example 3
[0105] A magnesium hydride-TiFeMn composite hydrogen storage material. The steps not otherwise specified are the same as those in Example 1, except that the composition of the TiFe-based hydrogen storage alloy powder is different from that in Example 1. The alloy powder in Comparative Example 3 contains only three components: Ti, Fe, and Mn, with the atomic percentages being: Ti content of 50 at.%, Fe content of 46 at.%, and Mn content of 4 at.%. The resulting magnesium-based composite hydrogen storage material is named #4-TiFeMn.
[0106] In order to demonstrate the hydrogen storage performance of #4-TiFeMn, hydrogen absorption and desorption kinetics tests were carried out.
[0107] The results of hydrogen absorption kinetics test are as follows Figure 4 As shown, at 250 °C and 3 MPa, the maximum hydrogen absorption capacity is 2.6 wt.%, and it takes 15 s to reach 70% of the maximum hydrogen absorption capacity;
[0108] The results of hydrogen release kinetics test are as follows Figure 5 As shown, under vacuum conditions at 250°C, the amount of hydrogen released in 1000s is 2.4wt.%, and the initial hydrogen release temperature is 230°C.
[0109] Comparison of the hydrogen absorption and desorption test results with those of Example 1 shows that adding TiFeMnCo powder to MgH2 can better reduce the minimum hydrogen desorption temperature of the composite material than TiFeMn powder, and the effect of improving the hydrogen storage capacity and hydrogen absorption and desorption rate is also better than TiFeMn powder.
[0110] The test results show that the Mn element has achieved the following technical effects in the technical solution:
[0111] 1. Improve the maximum hydrogen absorption capacity of the material, thereby increasing the maximum hydrogen absorption capacity of the composite material;
[0112] 2. Promote the mutual transformation of Mg phase and MgH2 phase, which is beneficial to the diffusion of hydrogen atoms and increases the speed of hydrogen absorption and desorption.
[0113] Comparative Example 4
[0114] A magnesium hydride-TiFeCo composite hydrogen storage material. The steps not otherwise specified are the same as those in Example 1, except that the composition of the TiFe-based hydrogen storage alloy powder is different from that in Example 1. The alloy powder in Comparative Example 4 contains only Ti, Fe, and Co, with the atomic percentages being: 50 at.%, 46 at.%, and 4 at.% Ti. The resulting magnesium-based composite hydrogen storage material is named #5-TiFeCo.
[0115] In order to demonstrate the hydrogen storage performance of #5-TiFeCo, hydrogen absorption and desorption kinetics tests were carried out.
[0116] The results of hydrogen absorption kinetics test are as follows Figure 4 As shown, at 250 °C and 3 MPa, the maximum hydrogen absorption capacity is 1.2 wt.%, and it takes 50 s to reach 70% of the maximum hydrogen absorption capacity;
[0117] The results of hydrogen release kinetics test are as follows Figure 5 As shown in the figure, under vacuum conditions at 250°C, the amount of hydrogen released in 1000s is only 0.1wt.%.
[0118] Comparison of the hydrogen absorption and desorption test results with those of Example 1 shows that adding TiFeMnCo powder to MgH2 can better increase the maximum hydrogen absorption capacity of the composite material than TiFeCo powder, and the effect of increasing the hydrogen absorption and desorption rate is also better than that of TiFeCo powder.
[0119] The test results show that the Co element has achieved the following technical effects in the technical solution:
[0120] 1. Can reduce the platform pressure of TiFe alloy;
[0121] 2. It can significantly reduce the initial hydrogen desorption temperature of MgH2, so that the initial hydrogen desorption temperature of the composite material is significantly reduced.
[0122] Comparative Example 5
[0123] A magnesium hydride-TiFe composite hydrogen storage material. The steps not otherwise specified are the same as those in Example 1, except that the composition of the TiFe-based hydrogen storage alloy powder is different from that in Example 1. The alloy powder in Comparative Example 5 contains only Ti and Fe, with the atomic percentages being 50 at.% Ti and 50 at.%. The resulting magnesium-based composite hydrogen storage material is designated #6-TiFe.
[0124] In order to demonstrate the hydrogen storage performance of #6-TiFe, hydrogen absorption and desorption kinetics tests were carried out.
[0125] The results of hydrogen absorption kinetics test are as follows Figure 4 As shown, at 250 °C and 3 MPa, the maximum hydrogen absorption capacity is 2.0 wt.%, and it takes 20 s to reach 70% of the maximum hydrogen absorption capacity;
[0126] The results of hydrogen release kinetics test are as follows Figure 5 As shown in the figure, under vacuum conditions at 250℃, the amount of hydrogen released in 1000s is only 2.0wt.%, and the lowest hydrogen release temperature is 250℃.
[0127] As shown in Table 1, a comparison of the hydrogen absorption and desorption rates of the various embodiments of the present invention and the comparative examples shows that the hydrogen absorption kinetics of the #1-10TiFeMnCo obtained in Example 1 of the present invention is improved by 37-80%; the hydrogen absorption amount is increased by 1.2-3.6 wt.%; the hydrogen desorption amount per 1000 s is greater than that of the comparative example, and the hydrogen desorption temperature is reduced to 220°C.
[0128] Comparison of the hydrogen absorption and desorption test results with those of Comparative Example 3 shows that adding TiFeMn powder to MgH2 can better improve the hydrogen absorption and desorption rate and the maximum hydrogen storage capacity of the composite material than TiFe powder.
[0129] The test results combined with Comparative Example 4 can be used to draw the following conclusions: the technical effect of the Co element in the technical solution is basically consistent with the conclusions obtained in Example 1 and Comparative Example 3;
[0130] Similarly, the test results combined with Comparative Example 3 can be used to draw the following conclusions: the technical effect of the Mn element in the technical solution is basically consistent with the conclusions obtained in Example 1 and Comparative Example 4.
[0131] However, from the comparative analysis of the specific technical effects of hydrogen absorption and desorption performance, it can be seen that the effect of adding Co element or Co element alone to TiFe alloy on improving the hydrogen absorption and desorption performance is far less than that of adding Co element and Mn element at the same time, which shows that there is a synergistic effect between Co element and Mn element in the technical solution of the present invention.
Claims
1. An activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material, characterized in that: The composite hydrogen storage material is made by ball milling TiFeMnCo and MgH2, and the size of the composite hydrogen storage material is 1-6μm; wherein MgH2 is the matrix material, and TiFeMnCo is evenly distributed on the surface of MgH2; the TiFeMnCo is made by smelting method; XRD test results show that TiFeMnCo contains MgH2 phase and TiFe 0.92 Mn 0.04 Co 0.04 phase and a small amount of α-Fe phase. The Rietveld method refinement results show that the content of MgH2 phase is 82%-84%, TiFe 0.92 Mn 0.04 Co 0.04 The content of the phase is 11%-13%, and the content of the α-Fe phase is 5%-6%.
2. The magnesium hydride-TiFeMnCo composite hydrogen storage material according to claim 1, characterized in that: When the material is used as a hydrogen storage material, the magnesium hydride-TiFeMnCo composite hydrogen storage material obtained by the smelting method can achieve a maximum hydrogen absorption capacity of 4.8wt.% at 250°C and 3MPa; under vacuum conditions at 250°C, it can reach 70% of the maximum hydrogen release capacity in 9s, and can release hydrogen at 220°C.
3. A method for preparing an activation-free magnesium hydride-TiFeMnCo composite hydrogen storage material, characterized in that The following steps are involved: Step 1, melting the TiFeMnCo ingot, first, to meet a certain alloy component atomic percentage, titanium block, iron block, cobalt block, and manganese block are subjected to high-frequency magnetic levitation melting under certain conditions, after the melting is completed, the ingot is cooled to room temperature using a water-cooled copper crucible to obtain a TiFeMnCo ingot; In step 1, the alloy composition atomic percentage of the TiFeMnCo ingot is 50 at.%, 46 at.%, 2 at.%, and 2 at.% of Mn. The obtained alloy is TiFe 0.92 Mn 0.04 Co 0.04 alloy; In the step 1, the smelting power of the high-frequency magnetic levitation smelting is 25-30kW; Step 2, refining the TiFeMnCo ingot, refining the TiFeMnCo ingot obtained in step 1 to obtain TiFeMnCo powder; In step 2, the conditions for refinement are: first mechanically crushing, and then screening with a sieve of 2000 mesh; Step 3, preparation of magnesium hydride-TiFeMnCo composite hydrogen storage material based on smelting method, after mixing TiFeMnCo powder and MgH2, composite ball milling is performed under certain conditions to obtain magnesium hydride-TiFeMnCo composite hydrogen storage material based on smelting method, referred to as MgH2-TiFeMnCo; In step 3, the TiFeMnCo powder accounts for 10 wt.% of the total mass of the composite hydrogen storage material; In step 3, the conditions for composite ball milling are as follows: under argon conditions, stainless steel balls are used as grinding beads, the ball-to-material ratio is 35-40:1, the ball milling speed is 230-250 rpm, and the ball milling method is forward and reverse intermittent ball milling, specifically, the ball milling time is 30 minutes, the pause time is 10 minutes, and then reverse ball milling, and the total ball milling time is 38-42 hours.