A rare earth Ce-removing Ti-Mn-based hydrogen storage alloy and a preparation method thereof

Abstract

This invention discloses a rare-earth Ce-purified Ti-Mn-based hydrogen storage alloy and its preparation method. The preparation method includes the following steps: mixing FeV80 with Ce and melting it in a vacuum arc melting furnace under an argon protective atmosphere; polishing the surface of the FeV80-yCe master alloy to remove the surface-enriched impurity phases, obtaining a purified master alloy; mixing the purified master alloy with Ti, Zr, Mn, and Cr raw materials and arc melting it under vacuum conditions; after melting, cooling it to room temperature with the furnace to obtain the rare-earth Ce-purified Ti-Mn-based hydrogen storage alloy. This invention pre-treats FeV80 with Ce, and removes impurities enriched on the surface of the metal ingot through melting and then polishing. The process is simple and cost-controllable, fundamentally solving the problem of impurity deterioration in industrial raw materials, improving the hydrogen storage capacity of the hydrogen storage alloy at 5MPa hydrogen pressure, and meeting the comprehensive performance requirements for industrial applications.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage materials technology, and in particular to a rare earth Ce-purified Ti-Mn-based hydrogen storage alloy and its preparation method. Background Technology

[0002] Ti-Mn based Laves phase hydrogen storage alloys have significant application value in on-board hydrogen storage and distributed energy storage due to their high hydrogen storage capacity, excellent kinetic performance, and low raw material cost. In industrial production, low-cost FeV80 alloys are often used to replace pure V, which can significantly reduce raw material costs. However, industrial-grade FeV80 generally contains impurities such as Al, Si, and O. These impurities easily combine with Ti and Zr to form high-melting-point oxides or intermetallic compounds, causing lattice distortion, elemental segregation, and a reduction in the content of hydrogen-absorbing elements in the main phase. This leads to a decrease in the alloy's hydrogen storage capacity and a deterioration of plateau characteristics, making it difficult to meet the engineering specifications of a cost ≤100 yuan / kg and a hydrogen storage capacity ≥2.0 wt% under a hydrogen pressure of 5 MPa.

[0003] Currently, the modification of Ti-Mn based hydrogen storage alloys mainly focuses on composition optimization and element substitution. Although these methods can improve hydrogen storage performance to a certain extent, they cannot eliminate the deterioration effect caused by impurities in FeV80 from the root. Summary of the Invention

[0004] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the purpose of this invention is to provide a method for preparing a Ti-Mn-based hydrogen storage alloy with rare earth Ce impurity removal. The method achieves deep impurity removal by Ce pretreatment of FeV80, thereby improving the hydrogen storage capacity of the alloy under 5MPa hydrogen pressure and meeting the requirements of industrial application in terms of comprehensive performance.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing a rare-earth Ce-purified Ti-Mn-based hydrogen storage alloy, comprising the following steps:

[0007] (1) FeV80 and Ce are mixed and melted in a vacuum arc melting furnace under an argon protective atmosphere. The melting is repeated multiple times to prepare FeV80-Ce master alloy with surface enriched impurity phases. The mass of Ce is 1~5wt% of the mass of FeV80. The impurity phases include Ce2O3 and CeAlO2.

[0008] (2) Polish the surface of the FeV80-Ce master alloy obtained in step (1) to remove the impurity phases enriched on the surface and obtain the purified FeV80-Ce master alloy.

[0009] (3) The purified FeV80-Ce master alloy obtained in step (2) is mixed with Ti, Zr, Mn and Cr raw materials and placed in a vacuum arc melting furnace for arc melting under vacuum conditions, and the melting is repeated multiple times.

[0010] (4) After the melting is completed, the furnace is cooled to room temperature to obtain a Ti-Mn based hydrogen storage alloy with rare earth Ce removed.

[0011] In some embodiments of the present invention, the Ti, Zr, Mn, and Cr raw materials mentioned in step (3) are formulated according to the general chemical formula (Ti 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 Add it according to the specified ratio.

[0012] In some embodiments of the present invention, the argon protective atmosphere described in step (1) is specifically implemented by first evacuating the vacuum to a degree ≤ 5 × 10⁻⁶. -3 Pa, then argon gas is introduced as a protective gas.

[0013] In some embodiments of the present invention, the vacuum condition described in step (3) is specifically a vacuum degree ≤ 5 × 10⁻⁶. -3 Pa.

[0014] In some embodiments of the present invention, in step (1), the Ce reacts with the Al and O impurities in FeV80 to generate impurities with higher melting points and preferentially precipitate out, and are directionally enriched on the surface of the FeV80 alloy.

[0015] In some embodiments of the present invention, the mass of Ce is 2.5 to 3.55 wt% of the mass of the FeV80-Ce master alloy.

[0016] The present invention also provides a rare earth Ce-removed Ti-Mn-based hydrogen storage alloy, which is prepared by the method for preparing the rare earth Ce-removed Ti-Mn-based hydrogen storage alloy.

[0017] This invention also provides a method for preparing FeV80-Ce master alloy, comprising the following steps:

[0018] FeV80 and Ce were mixed and melted in a vacuum arc furnace under an argon protective atmosphere. The melting process was repeated multiple times to prepare a FeV80-Ce master alloy with surface-enriched impurity phases. The mass of Ce was 1 to 5 wt% of the mass of the FeV80-Ce master alloy. The impurity phases included Ce2O3 and CeAlO2.

[0019] The surface of the obtained FeV80-Ce master alloy was ground and polished to remove the impurity phases enriched on the surface, thus obtaining a purified FeV80-Ce master alloy.

[0020] In some embodiments of the present invention, the mass of Ce is 2.5 to 3.5 wt% of the mass of FeV80.

[0021] The present invention also provides a FeV80-Ce master alloy, which is prepared by the method for preparing the FeV80-Ce master alloy.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) In this invention, FeV80 is first alloyed with Ce to form an intermediate alloy. Ce has a stronger affinity for O and Al than Ti and Zr, and can preferentially react with Al and O impurities in FeV80 to generate stable compounds with high melting points and low solubility, such as Ce2O3 and CeAlO2. These compounds have a lower density than the melt during the smelting process and will be directionally enriched on the surface of the FeV80 alloy. Impurities can be physically removed by polishing. The process is simple and easy to control, and is suitable for industrial-scale production.

[0024] (2) The purified FeV80-Ce intermediate alloy of the present invention is used to introduce Ce into the Ti-Mn based hydrogen storage alloy, thereby eliminating the problems of lattice distortion and element segregation caused by Al and O impurities from the source, avoiding the impurity residue caused by Ce being directly added to the final alloy, and the final alloy composition is more stable and has better hydrogen storage capacity. Attached Figure Description

[0025] Figure 1 The XRD patterns of the original FeV80 (a) and FeV80-Ce master alloy (unpolished) (b) are shown.

[0026] Figure 2 XRD pattern of the residue after polishing FeV80+3wt%Ce alloy.

[0027] Figure 3 BSE-EDS characterization spectra of the original FeV80 (a) and FeV80+3wt%Ce alloy (polished) (b).

[0028] Figure 4 BSE-EDS characterization spectrum of the residue after polishing FeV80+3wt%Ce alloy.

[0029] Figure 5 shows (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr0.05 PCT curves of alloys with yCe (y=0, 1, 3, 5 wt%).

[0030] Figure 6 shows (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 Van't Hoff curves for +yCe (y=0, 1, 3, 5 wt%) alloys.

[0031] Figure 7 For Comparative Example 2 (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The alloy is directly doped with 3wt% Ce(a) and (Ti) in Example 2 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 PCT curve of +3 wt%Ce master alloy (b) at 25 °C. Detailed Implementation

[0032] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0033] In the following embodiments, the hydrogen storage performance test uses a Sieverts hydrogen storage performance tester manufactured by Advance Material Corporation, USA, and specifically includes the following procedures:

[0034] (1) System calibration: Before conducting a series of alloy tests, the test system is calibrated using the built-in System Text to ensure that components such as pressure sensors and temperature control systems are operating normally.

[0035] (2) Sample loading and vacuuming: Weigh approximately 2.0 g of the above alloy powder into the glove box and load it into the sample rod. After tightening the sample rod, remove the glove box and fix the sample rod in the test position. After sealing, vacuum the sample at room temperature for 20 minutes to remove air and impurities from the sample and tubing to avoid interfering with the test process.

[0036] (3) Sample activation: At room temperature, 50 atm of hydrogen gas is introduced into the chamber, and the pressure change inside the sample rod is recorded. When the pressure inside the sample rod no longer decreases, it can be considered that the sample has absorbed hydrogen saturation. At this time, the excess hydrogen gas is removed, and the sample is heated to 300 °C for 0.5 h of vacuum process, followed by cooling to room temperature, which completes one activation process. Usually, the activation process needs to be repeated three times until the sample is fully activated.

[0037] (4) PCT performance test: After setting the PCT test parameters (hydrogen pressure, hydrogen absorption and desorption time, sample mass, etc.), the test is performed directly in the system. In addition, the PCT curves at three different temperatures are tested to analyze the thermodynamic properties of the material.

[0038] Example 1

[0039] Weigh out three 30g portions of industrial FeV80, and add 0.3g, 0.9g, and 1.5g of Ce respectively (i.e., 1 wt%, 3 wt%, and 5 wt%). Mix thoroughly and place in a vacuum arc melting furnace, then evacuate to 4×10⁻⁶. -3 Pa was subjected to electric arc melting, and the melting was repeated 5 times. After cooling, FeV80-Ce master alloy was obtained. The surface of the master alloy was polished to remove the impurity phases enriched on the surface, and purified FeV80-Ce master alloy was obtained, which was denoted as FeV80+yCe (y=1 wt%, 3wt%, 5wt%) master alloy.

[0040] Example 2

[0041] Press (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The composition ratio was determined by weighing out Ti, Zr, Mn, and Cr raw materials (purity ≥ 99.9%), with an additional 5 wt% of Mn added as a compensation due to its high volatility at high temperatures. These were then mixed thoroughly with the FeV80+yCe (y = 1 wt%, 3 wt%, 5 wt%) master alloy prepared in Example 1, followed by vacuum arc melting at a vacuum degree of 4 × 10⁻⁶. -3 Pa, repeatedly melted 5 times, and cooled to obtain (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 +yCe (y=1 wt%, 3wt%, 5wt%) hydrogen storage alloy.

[0042] Comparative Example 1

[0043] This comparative example did not add Ce, i.e. (Ti0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 Hydrogen storage alloys were prepared using Ti, Zr, Mn, Cr, and FeV80 as raw materials and under the same process conditions as in Example 2.

[0044] Comparative Example 2

[0045] This comparative example directly in (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The alloy raw materials contain 3 wt% Ce. A hydrogen storage alloy was prepared using Ti, Zr, Mn, Cr, FeV80, and Ce as raw materials, under the same process conditions as in Example 2.

[0046] Test results:

[0047] XRD characterization:

[0048] Figure 1 In Figures (a) and (b), the XRD patterns of the original FeV80 and FeV80-Ce master alloy (unpolished) are shown respectively. As can be seen from the figure, the XRD pattern of the original FeV80 alloy shows obvious characteristic peaks of Al2O3 oxide, indicating that the raw material contains a large amount of Al and O impurities. In the FeV80-Ce master alloy, as the Ce addition increases, the characteristic peaks of Al2O3 gradually weaken and eventually disappear. At 3wt% Ce, the Al2O3 peaks completely disappear, and characteristic peaks of Ce2O3 and CeAlO2 impurity phases appear at the same time, proving that Ce can effectively remove oxide impurities in FeV80.

[0049] Figure 2 The XRD pattern of the residue after grinding FeV80+3wt%Ce alloy shows that the residue mainly contains characteristic peaks of Ce2O3 and CeAlO2, which is consistent with the Ce impurity removal mechanism. This proves that Ce combines with Al and O impurities to form stable compounds, which can be removed by grinding to purify the raw material.

[0050] BSE-EDS characterization:

[0051] Figure 3In the middle (a) and (b), respectively, are the BSE-EDS characterization spectra of the original FeV80 and the FeV80+3wt%Ce alloy (after polishing). The characterization results of the BSE image and EDS mapping of the original FeV80 alloy show that there are a large number of black Al and O enriched regions in the alloy, which are Al2O3 impurity phases. The BSE image and EDS mapping characterization results of the FeV80+3wt%Ce alloy show that the black Al and O enriched regions are significantly reduced, and the distribution of V and Fe elements is more uniform, proving that Ce impurity removal effectively eliminates the Al and O impurity phases in the raw materials.

[0052] Figure 4 The BSE-EDS characterization spectrum of the residue after polishing FeV80+3wt%Ce alloy shows that the contrast of O, Al and Ce elements in the residue is significantly increased, which is consistent with the XRD analysis results of Ce2O3 and CeAlO2, the main components of the residue, further verifying the Ce removal mechanism.

[0053] PCT performance test:

[0054] The hydrogen storage alloys prepared in Example 2 and Comparative Example 1 were subjected to PCT performance testing. The test results are shown in Table 1 below:

[0055] Table 1. (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 Hydrogen storage performance parameters of +yCe (y=1 wt%, 3 wt%, 5 wt%) alloys

[0056]

[0057] PCT test results show that: with the increase of rare earth content in the intermediate alloy, (Ti 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The plateau pressure of the +yCe alloy first increases and then decreases, while the maximum hydrogen storage capacity continuously increases, among which (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The maximum hydrogen storage capacity of the +3wt%Ce alloy exceeds 2.0wt%, and the enthalpy change of the alloy's dehydrogenation reaction (ΔH) d ) and entropy change (ΔS) dThe increase in Ce content is significant, leading to decreased hydride stability, easier dehydrogenation, and more favorable hydrogen adsorption / desorption kinetics. Considering both economics and performance, 3 wt% Ce is the optimal addition amount.

[0058] Figure 5 shows (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The PCT curves of the +yCe alloy are shown in (a) to (d), where (a) and (d) are the PCT curves of the alloy at 25℃, 35℃ and 45℃ when y=0, 1, 3 and 5 wt%, respectively. It can be seen that as the Ce addition increases, the maximum hydrogen storage capacity of the alloy continues to increase. The capacity exceeds 2.0 wt% when Ce is added, and the plateau pressure is moderate, which is suitable for 5MPa operating conditions.

[0059] Figure 6 shows (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The Van't Hoff curves of +yCe (y=0, 1, 3, 5 wt%) alloys are shown, where (a)~(d) are the Van't Hoff curves of the alloys when y=0, 1, 3, and 5 wt%, respectively. The dehydrogenation enthalpy change and entropy change were obtained by fitting the Van't Hoff relationship. The results show that as the Ce addition increases, the values ​​of ΔHd and ΔSd increase, the hydride stability decreases, which is more conducive to the hydrogen absorption and desorption process. Furthermore, the high fit of the fitted curves indicates that the hydrogen storage performance test results are relatively accurate.

[0060] Figure 7 For Comparative Example 2 (Ti) 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 The alloy was directly doped with 3wt% Ce, similar to the alloy in Example 2 (Ti). 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 A comparison of the PCT curves of a +3 wt%Ce master alloy doped with 3 wt%C at 25°C shows that the hydrogen storage capacity of the alloy obtained by using the master alloy method is significantly higher than that of the alloy directly doped with Ce, further verifying the advantages of using the master alloy method.

[0061] In this invention, Ce preferentially reacts with Al and O in FeV80 to form high-melting-point compounds such as Ce2O3 and CeAlO2. These compounds are enriched on the surface of the metal ingot through melting and then removed by grinding, achieving deep purification of the raw materials. The resulting hydrogen storage alloy has a maximum hydrogen storage capacity of 2.02 wt% at 5 MPa hydrogen pressure and 298 K, with a raw material cost of ≤100 RMB / kg, meeting the requirements for industrial application of solid-state hydrogen storage. This invention features a simple process, controllable cost, and fundamentally solves the problem of impurity deterioration in industrial raw materials, demonstrating significant engineering application value.

[0062] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a rare-earth Ce-purified Ti-Mn-based hydrogen storage alloy, characterized in that, Includes the following steps: (1) FeV80 and Ce are mixed and melted in a vacuum arc melting furnace under an argon protective atmosphere. The melting is repeated multiple times to prepare FeV80-Ce master alloy with surface enriched impurity phases. The mass of Ce is 1~5wt% of the mass of FeV80. The impurity phases include Ce2O3 and CeAlO2. (2) Polish the surface of the FeV80-Ce master alloy obtained in step (1) to remove the impurity phases enriched on the surface and obtain the purified FeV80-Ce master alloy. (3) The purified FeV80-Ce master alloy obtained in step (2) is mixed with Ti, Zr, Mn and Cr raw materials and placed in a vacuum arc melting furnace for arc melting under vacuum conditions, and the melting is repeated multiple times. (4) After the melting is completed, the furnace is cooled to room temperature to obtain a Ti-Mn based hydrogen storage alloy with rare earth Ce removed.

2. The method for preparing the rare earth Ce-purified Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, The Ti, Zr, Mn, and Cr raw materials mentioned in step (3) are, according to the general chemical formula (Ti 0.9 Zr 0.1 ) 1.03 Mn 1.37 (FeV80) 0.41 Cr 0.05 Add it according to the specified ratio.

3. The method for preparing the rare earth Ce-purified Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, The argon protective atmosphere mentioned in step (1) is specifically implemented by first evacuating the vacuum to a degree ≤ 5 × 10⁻⁶. -3 Pa, then argon gas is introduced as a protective gas.

4. The method for preparing the rare earth Ce-purified Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, The vacuum condition described in step (3) is specifically a vacuum degree ≤ 5 × 10⁻⁶. -3 Pa.

5. The method for preparing the rare earth Ce-purified Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, In step (1), Ce reacts with Al and O impurities in FeV80 to generate impurities with higher melting points, which are preferentially precipitated and directionally enriched on the surface of FeV80 alloy.

6. The method for preparing the rare earth Ce-purified Ti-Mn-based hydrogen storage alloy according to claim 1, characterized in that, The mass of Ce is 2.5 to 3.55 wt% of the mass of the FeV80-Ce master alloy.

7. A rare-earth Ce-purified Ti-Mn-based hydrogen storage alloy, characterized in that, It is prepared by the method for preparing rare earth Ce-removed Ti-Mn-based hydrogen storage alloy according to any one of claims 1 to 6.

8. A method for preparing a FeV80-Ce master alloy, characterized in that, Includes the following steps: FeV80 and Ce were mixed and melted in a vacuum arc furnace under an argon protective atmosphere. The melting process was repeated multiple times to prepare a FeV80-Ce master alloy with surface-enriched impurity phases. The mass of Ce was 1 to 5 wt% of the mass of the FeV80-Ce master alloy. The impurity phases included Ce2O3 and CeAlO2. The surface of the obtained FeV80-Ce master alloy was ground and polished to remove the impurity phases enriched on the surface, thus obtaining a purified FeV80-Ce master alloy.

9. The method for preparing the FeV80-Ce master alloy according to claim 8, characterized in that, The mass of Ce is 2.5 to 3.5 wt% of the mass of FeV80.

10. FeV80-Ce master alloy, characterized in that, It is prepared by the method for preparing FeV80-Ce master alloy according to any one of claims 8 to 9.

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