Mg-Ni-Nd hydrogen storage alloy with poison resistance and regeneration performance and application and regeneration method of Mg-Ni-Nd hydrogen storage alloy

Abstract

The invention discloses an Mg-Ni-Nd hydrogen storage alloy with poison resistance and regeneration performance, the Mg-Ni-Nd hydrogen storage alloy comprises Nd4Mg80Ni8, Mg and Mg2Ni phases at the same time, and after hydrogen absorption and desorption activation, the Mg-Ni-Nd hydrogen storage alloy is decomposed into Mg, Mg2Ni and NdH2.61 phases in situ; the content of Mg is 85-90%, the content of Ni is 6-10%, and the content of Nd is 2-5%. The invention discloses a simulated poisoning treatment and poisoning regeneration method of an Mg-Ni-Nd hydrogen storage alloy. The poisoning atmosphere is mixed gas of CO2 and H2; the regeneration atmosphere is pure H2 atmosphere. When the alloy is used as a hydrogen storage alloy, the maximum hydrogen absorption amount reaches 5.40 wt.%. When the alloy is used as an anti-poisoning hydrogen storage alloy, the cycle index is larger than 300 times, the maximum hydrogen absorption amount is 5.10 wt%, and the CO2 concentration in the poisoning atmosphere condition and the CO2 concentration in the air are the same order of magnitude. When the alloy is used as a renewable hydrogen storage alloy, the maximum hydrogen absorption amount is 5.29 wt.%, and the hydrogen absorption amount is recovered to 97.96% of the initial hydrogen absorption amount.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen storage materials, and specifically to an Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration properties, and its application and regeneration method. Background Art

[0002] Magnesium-based hydrogen storage materials are a type of solid-state hydrogen storage materials, with a theoretical hydrogen storage capacity as high as 7.6 wt.%, and significant cost advantages. However, magnesium-based hydrogen storage materials have the problem of poisoning failure in practical applications. The reason is that MgH2 is extremely vulnerable to poisoning by impurity gases such as CO2, O2, H2O, and CO, and loses its hydrogen storage capacity after a small number of cycles. The poisoning mechanism is mainly attributed to two aspects: 1. Impurity gases occupy the hydrogen dissociation active sites through physical and chemical adsorption, reducing the surface catalytic activity; 2. Oxidation / carbonization reactions occur on the alloy surface to form a passivation layer, hindering the hydrogen diffusion kinetics. This leads to a sharp deterioration in the cycle stability of the material, becoming the core obstacle restricting its commercial application. For example, in the existing literature 1, (《The storage of industrially pure hydrogen in magnesium.》International Journal of Hydrogen Energy, 1993, 18(4): 297-300.), under the condition of 2% CO2 + H2 atmosphere, the dehydrogenation temperature is 395 °C, and the dehydrogenation pressure is 2.5 bar, MgH2 cannot dehydrogenate; after switching to a pure H2 atmosphere, the dehydrogenation amount only recovers to 76.77% of the original dehydrogenation amount. This literature shows that Mg-based hydrogen storage materials are extremely vulnerable to the influence of impurity gases. In response to the above problems, the existing anti-poisoning strategies are mainly of two types: 1. Surface modification; 2. Alloying.

[0003] The basic principle of improving the anti-poisoning performance through surface modification is to change the surface composition and structure of the alloy to provide a filter-like effect - allowing H2 to pass through, but blocking poisoning gases represented by CO2 from passing through, achieving selective permeation of gas molecules, and at the same time improving the catalytic activity of the alloy, thereby enhancing the anti-poisoning performance of the alloy. For example, in the existing literature 2, (《Effects of impurity gases on hydrogen storage properties of fluoride-containing AZ61 magnesium alloys》International Journal of Hydrogen Energy, 2025, 105, 923-931.) the theoretical hydrogen absorption capacity of the AZ61 alloy can reach 6.0 wt.%, but under the poisoning condition of CO2, a passivation layer mainly composed of MgO and MgCO3 will be formed, resulting in the inability of H2 to penetrate into the matrix phase for diffusion and nucleation, that is, it completely lacks anti-poisoning performance. Therefore, this technical solution provides the effect of a filter by preparing a dense MgF2 coating on the surface of the AZ61 alloy, thereby achieving an increase in the hydrogen absorption capacity from 0 wt.% to 1.10 - 1.50 wt.% under poisoning conditions, that is, changing from completely lacking anti-poisoning performance to having anti-poisoning performance. Further, through vacuum annealing at a regeneration temperature of 400 °C and a regeneration time of 4 h under vacuum conditions, regeneration after poisoning is achieved, obtaining a technical effect that the hydrogen absorption capacity reaches 3.5 wt.% under the conditions of a hydrogen absorption temperature of 375 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 30 min, that is, the hydrogen absorption capacity can only be restored to 58.3% of the theoretical hydrogen absorption capacity.

[0004] However, this technical solution has two technical problems: 1. Technical problems caused by the anti-poisoning coating; 2. Technical problems with a complex regeneration method, specifically.

[0005] 1. Technical problems caused by the anti-poisoning coating.

[0006] In the existing literature 2, this technical problem is demonstrated by generating MgF2 coatings through ball milling and immersion methods respectively.

[0007] In the ball milling method, due to the intense mechanical collision during the ball milling process, the formed fluoride is not sufficient to completely cover the entire alloy particle, resulting in the formation of a MgO passivation layer when contacting CO2, hindering the reaction between H and Mg, and causing the hydrogen storage capacity and kinetics to deteriorate sharply. Therefore, the coating prepared based on the ball milling method cannot completely wrap the matrix phase, and CO2 can penetrate into the alloy matrix in a poisoning atmosphere, resulting in the complete inability to obtain anti-poisoning performance;

[0008] In the immersion method, the MgF2 coating formed by chemical reaction has higher density. Therefore, the coating prepared by the immersion method realizes the anti-poisoning performance.

[0009] In addition, this experiment also shows that even though the coating prepared by the immersion method has better anti-poisoning effect, due to the hydrogen-induced volume change, local cracking of the coating may still occur, allowing some CO2 to penetrate the coating and form a Mg passivation layer, reducing the anti-poisoning performance of the alloy.

[0010] 2. The technical problem of complex regeneration method.

[0011] This technical problem is reflected in the existing literature 2 that when directly regenerating in a pure H2 atmosphere, the regeneration effect cannot be achieved. That is, this technical solution must perform the aforementioned vacuum annealing additionally to obtain the regeneration technical effect. In other words, "vacuum annealing" is an essential technical feature of this technical solution.

[0012] The above technical problem is also reflected in the existing literature 3 (《Surface-modified advanced hydrogen storage alloys for hydrogen separation and purification.》Journal of Alloys and Compounds, 2011, 509: S555-S561.), where the theoretical hydrogen absorption capacity of the AB5 alloy (A = La 0.34 Ce 0.50 (Pr, Nd) 0.16 ; B = Ni 0.63 Co 0.13 Mn 0.12 Al 0.12 ) can reach 1.4 wt.%. However, after exposure to air, that is, after poisoning, a passivation layer mainly composed of RE2NiO4 will be formed, preventing H2 from penetrating into the matrix phase for diffusion and nucleation, that is, it does not have anti-poisoning performance. Therefore, this technical solution prepares a Pd composite coating on the surface of the AB5 alloy by chemical deposition to improve the catalytic activity for H, thereby obtaining anti-air poisoning performance. This technical solution has the same technical problem as in the literature 2, that is, the hydrogen storage performance of the alloy is damaged due to the cracking of the anti-poisoning coating.

[0013] Therefore, it can be seen from the existing literature 2 and the existing literature 3 that there are problems of coating cracking leading to a decrease in hydrogen storage performance and cumbersome processes in achieving anti-poisoning performance based on surface modification.

[0014] The basic principle of improving poisoning resistance through alloying is to introduce other elements into the hydrogen storage alloy, change the electronic structure of the hydrogen storage alloy, thereby causing changes in the electronic effect, reducing the adsorption energy of impurity gases, i.e., poisoning gases, and ultimately achieving a reduction in the adsorption amount of impurity gases and improving the poisoning resistance of the alloy. For example, in the existing literature 4, (《The influence of atmospheric CO2 on the surface properties of Mg2NiH4 and a comparison with some hydrogen storage alloys》), through XPS analysis of Mg2Ni, Mg2NiH4, and Mg2Cu exposed to air, it is proved that in the poisoning process dominated by chemisorption, there are significant differences in the adsorption intensity of CO2 under different alloy compositions, that is, through composition design, namely alloying, the poisoning resistance can be achieved.

[0015] To further prove the influence of alloy composition on poisoning resistance. For example, in the existing literature 5, (《Dependence of constituent elements of AB5 type metal hydrides on hydrogenation degradation by CO2 poisoning》Journal of Alloys and Compounds, 2015, 647:198 - 203.), by introducing different elements into the LaNi5 alloy, the adsorption energy of the alloy for impurity gases, i.e., poisoning gases, can be reduced, and the improvement of the alloy's poisoning resistance can be achieved. Specifically, under the conditions of a hydrogen absorption temperature of 20 °C and a hydrogen absorption pressure of 0.9 MPa, the hydrogen absorption performance of the CaNi5 alloy reaches 1.13 wt.%, far lower than the theoretical hydrogen absorption amount. That is to say, the poisoning resistance is almost negligible and cannot meet the application requirements.

[0016] Meanwhile, another solution is to regenerate the poisoned alloy. Its basic principle is that under the influence of a poisoning atmosphere, a passivation layer forms on the surface of the hydrogen storage alloy, which hinders the dissociation and diffusion of H2 on the alloy surface. Therefore, according to the above principle, after the hydrogen storage phase in the alloy matrix that is not affected by the poisoning gas is treated by a regeneration process, the hydrogen absorption performance can be restored. For example, in the existing literature 7, (《Reactivity during cycling of nanocrystalline Mg-based hydrogen storage compounds》International Journal of Hydrogen Energy, 2002, 27(9), 909-913.) the theoretical hydrogen absorption capacity of MgH2 + 5at%V is 5.5wt.%. Although under the poisoning condition of CO2, the hydrogen absorption capacity is only 0.5wt.%, that is, it does not have anti-poisoning performance. However, after switching to a pure H2 atmosphere, the hydrogen absorption capacity is restored to 3.75wt.%, realizing the regeneration of hydrogen absorption performance. The reason is that under the condition of a pure H2 atmosphere, the active sites are no longer occupied by CO2 molecules, and the dissociation and diffusion process of H2 on the alloy surface is not affected. However, the regeneration degree of the hydrogen storage performance of this technical solution is low, that is, complete regeneration cannot be achieved. The reason is that the main hydrogen storage phase Mg in the matrix is partially converted into a MgO phase without hydrogen absorption capacity under the poisoning condition of CO2, resulting in an irreversible decrease in the effective hydrogen absorption capacity.

[0017] According to the existing literature, the following conclusions can be obtained, that is, the technical problems existing in the existing literature: Since the hydrogen storage phase in the current hydrogen storage alloy is affected by the poisoning gas, it is impossible to directly regenerate in a pure H2 atmosphere. Specifically, it is reflected in the following 3 aspects:

[0018] 1. The problem of blocked hydrogen diffusion path caused by CO2 chemisorption;

[0019] 2. The lack of a hydrogen storage phase protection mechanism;

[0020] 3. The problem of complex regeneration process. Summary of the Invention

[0021] The purpose of the present invention is to provide a Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration performance, its application and regeneration method in order to overcome the easy poisoning characteristics of Mg-based hydrogen storage materials.

[0022] The basic principle of the present invention is as follows:

[0023] 1. By introducing rare earth elements (RE), a Mg-Ni-RE ternary alloy system is constructed. After hydrogenation, this system undergoes spontaneous phase separation to form Mg phase, Mg2Ni phase, and RE-H metal hydride phase. Among them, the RE-H phase preferentially reacts with CO2 through selective chemical adsorption to in-situ generate RE-O metal oxide phase, forming a dynamic self-protection mechanism, which effectively prevents the active sites of the Mg phase from being inactivated due to poisoning.

[0024] 2. Based on the selective preferential adsorption characteristics of CO2 on the alloy surface, the formation of a continuous dense passivation layer in traditional magnesium-based hydrogen storage alloys on the material surface is avoided, thus eliminating the necessary steps of subsequent complex heat treatment processes to eliminate the influence of the passivation layer.

[0025] To achieve the above objectives, the present invention adopts the following technical solutions:

[0026] A Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration performance, the components of the Mg-Ni-Nd hydrogen storage alloy simultaneously include Nd4Mg 80 Ni8, Mg, and Mg2Ni phase, which are in-situ decomposed into Mg, Mg2Ni, and NdH 2.61 phase after hydrogen absorption and desorption activation; the content of Mg is 85 - 90%, the content of Ni is 6 - 10%, and the content of Nd is 2 - 5%.

[0027] A method for simulating poisoning treatment and poisoning regeneration of a Mg-Ni-Nd hydrogen storage alloy, as follows:

[0028] The method for simulating poisoning treatment is as follows. First, under the condition of a poisoning atmosphere, at a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 60 min, the activated Mg-Ni-Nd alloy, simply referred to as Alloy-A, is subjected to a hydrogen absorption test. Then, under vacuum conditions, at a hydrogen desorption temperature of 300 °C and a hydrogen desorption time of 60 min, a hydrogen desorption test is carried out, and thus a single simulation of poisoning treatment is completed. Finally, the poisoning treatment operation is repeated until the hydrogen storage performance reaches a stable state, and the poisoned Mg-Ni-Nd alloy, simply referred to as Alloy-P, can be obtained.

[0029] The poisoning atmosphere is a mixed gas of CO2 and H2;

[0030] The method for poisoning regeneration is as follows. First, under the condition of a regeneration atmosphere, at a hydrogen absorption temperature of 300 °C, an inhalation pressure of 3 MPa, and a hydrogen absorption time of 120 min, Alloy-P is subjected to a hydrogen absorption test. Then, under vacuum conditions, at a hydrogen desorption temperature of 300 °C and a hydrogen desorption time of 120 min, a hydrogen desorption test is carried out, and thus a single poisoning regeneration of the Mg-Ni-Nd hydrogen storage alloy is completed, obtaining the regenerated Mg-Ni-Nd alloy, simply referred to as Alloy-R.

[0031] The regeneration atmosphere is a pure H2 atmosphere.

[0032] When used as a hydrogen storage alloy, under the condition of a pure H2 atmosphere, at a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 30 min, the maximum hydrogen absorption capacity is greater than 5.30 wt.%.

[0033] When used as an anti-poisoning hydrogen storage alloy, under the poisoning atmosphere condition, where the volume fraction of CO2 is 0.01%, at a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, with the number of cycles greater than 300 times, and a hydrogen absorption time of 20 min, the maximum hydrogen absorption capacity is greater than 5.0 wt.

[0034] The CO2 concentration in the poisoning atmosphere condition is of the same order of magnitude as the CO2 concentration in the air.

[0035] When used as a renewable hydrogen storage alloy, under the condition of a pure H2 atmosphere, at a hydrogen absorption temperature of 300 °C and a hydrogen absorption pressure of 3 MPa,

[0036] When the number of poisoning regeneration times is 1, the hydrogen absorption time is 60 min, the maximum hydrogen absorption capacity is greater than 4.0 wt.%, and the hydrogen absorption capacity recovery is greater than 80% of the initial hydrogen absorption capacity;

[0037] When the number of poisoning regeneration times is 2, the hydrogen absorption time is 30 min to reach the maximum hydrogen absorption capacity, the maximum hydrogen absorption capacity is 5.2 wt.%, and the hydrogen absorption capacity recovery is greater than 95% of the initial hydrogen absorption capacity.

[0038] The technical effects of the present invention are known through detection:

[0039] It can be known through XRD detection that after poisoning cycling and subsequent regeneration treatment, the phase composition of the Mg-Ni-Nd alloy simultaneously includes the Mg phase, the Mg2Ni phase, the NdH 2.61 phase and the Nd2O3 phase, which verifies the expected chemical composition and crystal structure of the material.

[0040] It can be known through SEM detection that the micro-morphology of the regenerated Mg-Ni-Nd alloy is basically the same as that of the poisoned Mg-Ni-Nd alloy, that is, there are second-phase particles, clusters, and large particle phases dispersedly distributed on the alloy surface. However, the dispersion degree of the particles of the regenerated Mg-Ni-Nd alloy is significantly improved.

[0041] It can be known through the hydrogen absorption and desorption kinetic performance test that:

[0042] After activation, the Mg-Ni-Nd alloy has a hydrogen absorption capacity greater than 5.3 wt.% under the conditions of a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 60 min in a pure H2 atmosphere, demonstrating excellent initial hydrogen absorption and desorption capabilities of the material.

[0043] After activation, the Mg-Ni-Nd alloy has a hydrogen absorption capacity greater than 2.0 wt.% under the conditions of a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, a hydrogen absorption time of 60 min, and 2 cycles in a poisoned atmosphere.

[0044] After poisoning, the Mg-Ni-Nd alloy under the conditions of a hydrogen absorption temperature of 300 °C and a hydrogen absorption pressure of 3 MPa in a pure H2 atmosphere

[0045] When the number of poisoning regeneration times is 1, the hydrogen absorption time is 60 min, the maximum hydrogen absorption capacity is greater than 4.0 wt.%, and the hydrogen absorption capacity is restored to more than 80% of the initial hydrogen absorption capacity.

[0046] When the number of poisoning regeneration times is 2, the maximum hydrogen absorption capacity can be reached with a hydrogen absorption time of 30 min, the hydrogen absorption capacity is greater than 5.2 wt.%, and the hydrogen absorption capacity is restored to more than 95% of the initial hydrogen absorption capacity.

[0047] Therefore, through hydrogen storage performance testing, it can be seen that the Mg-Ni-Nd alloy has excellent anti-poisoning performance. After 2 cycles in a poisoned atmosphere, the hydrogen absorption capacity is still greater than 2.0 wt.%, and it has the characteristics of being used in air. At the same time, the Mg-Ni-Nd alloy has the characteristics of rapid self-repair and regeneration. After two times of poisoning regeneration, the hydrogen storage performance of the alloy is restored to the original state.

[0048] The present invention has the following advantages compared with the prior art:

[0049] 1. The designed Mg-Ni-Nd alloy of the present invention has good anti-poisoning performance under air conditions, and the influence of the poisoned atmosphere can be ignored, that is, the Mg-Ni-Nd alloy can be used for a long time and normally under air conditions.

[0050] 2. After being poisoned, the designed Mg-Ni-Nd alloy of the present invention can achieve the regeneration effect without additional vacuum annealing treatment and can be directly regenerated in a pure H2 atmosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is the XRD pattern of Alloy-A, Alloy-P-50000, and Alloy-R-50000 in Example 1 of the present invention;

[0052] Figure 2 is the SEM pattern of Alloy-A in Example 1 of the present invention;

[0053] Figure 3 It is the SEM spectrum of Alloy-P-50000 in Embodiment 1 of the present invention;

[0054] Figure 4 It is the SEM spectrum of Alloy-R-50000 in Embodiment 1 of the present invention;

[0055] Figure 5 It is the hydrogen absorption curve of Alloy-A and Alloy-P-50000 in Embodiment 1 of the present invention;

[0056] Figure 6 It is the hydrogen absorption curve of Alloy-R-50000 under different poisoning regeneration times in Embodiment 1 of the present invention;

[0057] Figure 7 It is the hydrogen absorption curve of MgNi-A and MgNi-P in Comparative Example 1 of the present invention;

[0058] Figure 8 It is the hydrogen absorption curve of MgNi-R under different poisoning regeneration times in Comparative Example 1 of the present invention;

[0059] Figure 9 It is the hydrogen absorption curve of Alloy-P-100 in Comparative Example 2 of the present invention;

[0060] Figure 10 It is the hydrogen absorption curve of Alloy-P-10000 in Comparative Example 3 of the present invention. Detailed implementation manners

[0061] The present invention further elaborates on the content of the present invention through embodiments in combination with the accompanying drawings of the specification, but it is not a limitation to the present invention.

[0062] Embodiment 1

[0063] In order to prove the anti-poisoning performance of the Mg-Ni-Nd hydrogen storage alloy and the effectiveness of the poisoning regeneration method, the Mg-Ni-Nd hydrogen storage alloy is subjected to simulated poisoning treatment.

[0064] The method of simulated poisoning treatment is as follows: First, under the poisoning atmosphere condition, at a hydrogen absorption temperature of 300°C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 60 min, the activated Mg-Ni-Nd alloy, simply referred to as Alloy-A, is subjected to a hydrogen absorption test. Then, under the vacuum condition, at a hydrogen desorption temperature of 300°C and a hydrogen desorption time of 60 min, a hydrogen desorption test is carried out, and thus one simulation poisoning treatment is completed. Finally, the poisoning treatment operation is repeated until the hydrogen storage performance reaches a stable state, and thus the poisoned Mg-Ni-Nd alloy, simply referred to as Alloy-P, can be obtained;

[0065] The poisoning atmosphere is a mixed gas of CO2 and H2. Moreover, the volume fraction of CO2 is 5%, that is, 50000 ppm. Therefore, the poisoning atmosphere in Example 1 is simply referred to as G-C50000. Meanwhile, the poisoned Mg-Ni-Nd alloy obtained in Specific Example 1 is simply referred to as Alloy-P-50000.

[0066] To prove the microstructure and phase morphology of Alloy-P-50000, that is, to simulate the effect of the poisoning treatment, XRD tests were carried out. Meanwhile, for comparison, XRD tests were carried out on Alloy-A. The test results are as Figure 1 shown.

[0067] The hydrogen-absorbed state of Alloy-A simultaneously contains the characteristic peaks of the MgH2 phase, the Mg2NiH4 phase, and the NdH 2.61 phase, which is consistent with the previous research results of the research group of the inventors of the present invention, that is, the existing literature 1-1;

[0068] Existing literature 1-1, Li Qian, Luo Qun, Sun Xuan, Pan Fusheng. A multiphase structure Mg-Ni-Nd hydrogen storage alloy based on in-situ activation method and its preparation method: 202310870697.7 [P]. 2025.

[0069] Among them,

[0070] The Mg phase and the MgH2 phase formed after hydrogen absorption are the main hydrogen storage phases;

[0071] The Mg2NiH4 phase and the NdH 2.61 phase are catalytic phases.

[0072] In addition to the characteristic peaks of the Mg phase, the Mg2Ni phase, and the NdH 2.61 phase, Alloy-P also has the characteristic peak of the Nd2O3 phase;

[0073] Among them, the Nd2O3 phase is a hydrogen storage inert phase.

[0074] The test results show that during the poisoning process, part of the NdH 2.61 phase is converted into the Nd2O3 phase. The reason is that under the condition of 300 °C, CO2 preferentially reacts with the NdH 2.61 phase on the surface of the Alloy-A alloy to generate the Nd2O3 phase.

[0075] To prove the microstructure and phase distribution of Alloy-P-50000, SEM tests were carried out. Meanwhile, for comparison, SEM tests were carried out on Alloy-A. The test results are as Figure 2 and Figure 3 shown.

[0076] The microstructure of Alloy-A is that there are fine and dispersedly distributed second-phase particles on the alloy surface. According to the existing literature 1-1, the composition of the second-phase particles is NdH formed in-situ after the alloy is hydrogenated. 2.61 phase and Mg2NiH4 phase. The role of the NdH 2.61 phase and Mg2NiH4 phase in the alloy is the pinning effect, that is, it inhibits the growth of MgH2 grains.

[0077] The microstructure of Alloy-P-50000 is that there are not only dispersedly distributed second-phase particles on the alloy surface, but also clusters and large particle phases. Combining the XRD test results, the composition of the large particle phase is Nd2O3 phase.

[0078] The test results show that during the poisoning process, since CO2 reacts with the NdH 2.61 phase to form the Nd2O3 phase, it changes the microstructure of the alloy, and moreover, weakens the pinning effect of the NdH 2.61 phase, resulting in the growth of the Nd2O3 phase into large particle phases.

[0079] To further prove the effect of the simulated poisoning treatment, the hydrogen absorption kinetics test was carried out on Alloy-P-50000. At the same time, for comparison, the hydrogen absorption kinetics test was carried out on Alloy-A. The test results are as Figure 5 shown.

[0080] Under the condition of pure H2 atmosphere, when the hydrogen absorption temperature of Alloy-A is 300 °C, the hydrogen absorption pressure is 3 MPa, and the hydrogen absorption time is 30 min, the maximum hydrogen absorption capacity reaches 5.40 wt.%.

[0081] Under the condition of G-C50000 atmosphere, when the hydrogen absorption temperature of Alloy-P-50000 is 300 °C, the hydrogen absorption pressure is 3 MPa, and the hydrogen absorption time is 60 min, the hydrogen absorption capacity reaches 2.18 wt.%.

[0082] The test results show that the Mg-Ni-Nd alloy still has hydrogen absorption performance under the condition of G-C50000 atmosphere, which proves that the Mg-Ni-Nd alloy has anti-poisoning performance. However, the hydrogen absorption capacity is significantly reduced, and the reduction amplitude is the initial hydrogen absorption capacity, that is, 41.7% of the hydrogen absorption capacity of Alloy-A. The reason is that the hydrogen absorption active site NdH 2.61 phase is transformed into a hydrogen storage inert phase Nd2O3 phase without hydrogen absorption activity in the poisoning atmosphere, and moreover, the Nd2O3 phase on the alloy surface adsorbs CO2 molecules during the poisoning process, thus reducing the dissociation and diffusion of hydrogen, that is, resulting in a decrease in the hydrogen absorption rate and hydrogen absorption capacity.

[0083] A method for poisoning regeneration of Mg-Ni-Nd hydrogen storage alloy. First, under the condition of a regeneration atmosphere, with a hydrogen absorption temperature of 300 °C, an absorption pressure of 3 MPa, and a hydrogen absorption time of 120 min, Alloy-P is subjected to a hydrogen absorption test. Then, under a vacuum condition, with a hydrogen desorption temperature of 300 °C and a hydrogen desorption time of 120 min, a hydrogen desorption test is carried out, thus completing one-time poisoning regeneration of the Mg-Ni-Nd hydrogen storage alloy to obtain a regenerated Mg-Ni-Nd alloy, simply referred to as Alloy-R; the regenerated Mg-Ni-Nd alloy obtained in Specific Example 1 is simply referred to as Alloy-R-50000;

[0084] The regeneration atmosphere is a pure H2 atmosphere.

[0085] In order to prove the microstructure and phase morphology of Alloy-R-50000, that is, the effect of poisoning regeneration, an XRD test is carried out. The test results are as Figure 3 shown. The phase composition of Alloy-R-50000 is the same as that of Alloy-P-50000, that is, it simultaneously contains characteristic peaks belonging to the phases of Mg, Mg2Ni, NdH 2.61 , Nd2O3. The test results show that the phase composition of the alloy cannot be changed during the poisoning regeneration process, that is, H2 cannot reduce the Nd2O3 phase to the NdH 2.61 phase. That is to say, the reason for poisoning regeneration has nothing to do with the phase composition.

[0086] Therefore, in order to further prove the effect of poisoning regeneration and prove the microstructure and phase distribution of Alloy-R-50000, an SEM test is carried out. The test results are as Figure 4 shown. The microstructure of Alloy-R-50000 is basically the same as that of Alloy-P-50000, that is, there are second-phase particles, clusters and large particle phases diffusely distributed on the alloy surface. However, the dispersion degree of the particles in Alloy-R-50000 is significantly improved.

[0087] In order to further quantitatively prove the effect of simulated poisoning regeneration, a hydrogen absorption kinetics test is carried out. The test results are as Figure 6 shown. Under the condition of a pure H2 atmosphere, with a hydrogen absorption temperature of 300 °C and a hydrogen absorption pressure of 3 MPa,

[0088] when the number of poisoning regeneration times is 1, the hydrogen absorption time is 60 min, the maximum hydrogen absorption amount is 4.44 wt.%, and the hydrogen absorption amount is restored to 83.77% of the initial hydrogen absorption amount;

[0089] when the number of poisoning regeneration times is 2, the maximum hydrogen absorption amount can be reached in 30 min, the maximum hydrogen absorption amount is 5.29 wt.%, and the hydrogen absorption amount is restored to 97.96% of the initial hydrogen absorption amount;

[0090] The test results show that the hydrogen absorption amount and the hydrogen absorption / desorption rate of Alloy-R-50000 are restored to the same level as that of Alloy-A, which proves that the Mg-Ni-Nd hydrogen storage alloy has the characteristic of being renewable after poisoning. Combining the XRD test and SEM test results, it can be known that the poisoning regeneration process has no substantial influence on the phase composition and microstructure of the Mg-Ni-Nd alloy. Further, it can be confirmed that the reason for the Mg-Ni-Nd hydrogen storage alloy having the characteristic of being renewable after poisoning is that NdH in the Alloy-R-50000 alloy 2.61 effectively protects the main hydrogen storage phase MgH2 phase. The Mg2Ni phase is not affected by CO2 gas during the poisoning process and still maintains its original crystal structure and catalytic activity.

[0091] To prove the influence of the poisoning treatment and regeneration treatment of the present invention on the performance, the existing literature is cited for comparison. As shown in the existing literature 1-2, under the condition of pure H2 atmosphere and the dehydrogenation temperature of 395 °C, the theoretical dehydrogenation amount of MgH2 is 6.85 wt.%. However, under the condition of 2% CO2 + H2 atmosphere, MgH2 immediately cannot absorb hydrogen; after switching to pure H2 atmosphere, the dehydrogenation amount only recovers to 5.83 wt.%, which is 76.77% of the original dehydrogenation amount. By comparison, it can be seen that the hydrogen storage performance recovery rate of the existing literature 1-2 after regeneration is only 76.77%, which is significantly lower than the regeneration performance of the present invention.

[0092] Note: The existing literature 1-2, Pedersen, A. S., & Larsen, B. The storage of industrially pure hydrogen in magnesium. International Journal of Hydrogen Energy, 1993, 18(4): 297-300.

[0093] To further prove the anti-poisoning performance of the Mg-Ni-Nd hydrogen storage alloy, Comparative Example 1 is provided, and the conventional commercial magnesium-based hydrogen storage alloy is subjected to simulated poisoning treatment and poisoning regeneration.

[0094] Comparative Example 1

[0095] Based on the simulated poisoning treatment and poisoning regeneration of the conventional commercial magnesium-based hydrogen storage alloy, the steps not specifically described are the same as those in Example 1. The differences are as follows: The conventional commercial magnesium-based hydrogen storage alloy is used, specifically Mg-30Ni is used instead of the Mg-Ni-Nd alloy. Mg-30Ni before poisoning is simply called MgNi-A, the obtained poisoned Mg-30Ni is simply called MgNi-P, and the regenerated Mg-30Ni is simply called MgNi-R.

[0096] The hydrogen absorption kinetics test results of MgNi-A are as follows Figure 7 As shown, under the condition of pure H2 atmosphere, with a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 30 min, the maximum hydrogen absorption capacity reaches 4.92 wt.%.

[0097] The hydrogen absorption kinetics test results of MgNi-P are as follows Figure 7 As shown, under the condition of G-C50000 atmosphere, with a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, a hydrogen absorption time of 60 min, and 2 times of poisoning treatment, the hydrogen absorption capacity is 0.31 wt.%.

[0098] Comparing with MgNi-A, it can be seen that the hydrogen absorption capacity of MgNi-P is significantly reduced, and the reduction amplitude is the initial hydrogen absorption capacity, that is, 93.7% of the hydrogen absorption capacity of MgNi-A.

[0099] At the same time, comparing with Alloy-P, it can be seen that the reduction amplitude of the hydrogen absorption capacity of MgNi-P is much larger than that of Alloy-P, that is, the poisoning resistance of Mg-30Ni is weaker than that of Mg-Ni-Nd alloy.

[0100] The hydrogen absorption kinetics test results of MgNi-R are as follows Figure 8 As shown, under the condition of pure H2 atmosphere, with a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 60 min, the first maximum hydrogen absorption capacity is 0.37 wt.%; the second is 0.40 wt.%.

[0101] Comparing with MgNi-P, it can be seen that the hydrogen absorption capacity of the alloy is restored to the initial hydrogen absorption capacity, that is, 8.13% of the hydrogen absorption capacity of MgNi-A.

[0102] At the same time, comparing with Alloy-R, it can be seen that after the regeneration treatment of Alloy-R, the hydrogen absorption capacity is restored to the initial hydrogen absorption capacity, that is, 97.96% of the hydrogen absorption capacity of Alloy-A, that is, the regeneration performance of Mg-30Ni is weaker than that of Mg-Ni-Nd alloy.

[0103] In order to prove the poisoning resistance of Mg-Ni-Nd hydrogen storage alloy, Comparative Example 2 and Comparative Example 3 are provided, and the Mg-Ni-Nd hydrogen storage alloy is simulated for poisoning treatment under different conditions.

[0104] Comparative Example 2

[0105] Based on the simulated poisoning treatment of Mg-Ni-Nd alloy under different atmosphere conditions, the steps not specifically described are the same as those in Example 1. The differences are as follows: The poisoning atmosphere is also a mixed gas of CO2 and H2. However, the volume fraction of CO2 is 0.01%, that is, 100 ppm, which is of the same order of magnitude as the CO2 concentration in the air. Therefore, the poisoning atmosphere in Example 1 is simply referred to as G-C100. At the same time, the poisoned Mg-Ni-Nd alloy obtained in Specific Example 2 is simply referred to as Alloy-P-100.

[0106] The hydrogen absorption kinetic test results of Alloy-P-100 are as Figure 9 shown. Under the condition of G-C100 atmosphere, at a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 20 min, the maximum hydrogen absorption capacity is 5.40 wt.%. Compared with Alloy-A, it can be seen that the reduction in the hydrogen absorption capacity of Alloy-P-100 is negligible, with a reduction amplitude of 0%. Combining the test results of Alloy-P-50000 obtained in Example 1, it can be known that Alloy-A has good poisoning resistance performance.

[0107] Furthermore, under the same conditions, when the number of cycles is 331 times, the maximum hydrogen absorption capacity is 5.10 wt.%. The test results show that under a relatively low concentration of the poisoning atmosphere, that is, under air conditions, Alloy-A has good poisoning resistance performance and the influence of the poisoning atmosphere is negligible.

[0108] It can be proved by Comparative Example 2 that Alloy-A can be used for a long time and normally under air conditions.

[0109] Comparative Example 3

[0110] Based on the simulated poisoning treatment of Mg-Ni-Nd alloy under different atmosphere conditions, the steps not specifically described are the same as those in Example 1. The differences are as follows: The poisoning atmosphere is also a mixed gas of CO2 and H2. However, the volume fraction of CO2 is 1%, that is, 10,000 ppm. Therefore, the poisoning atmosphere in Example 1 is simply referred to as G-C10000. At the same time, the poisoned Mg-Ni-Nd alloy obtained in Specific Example 3 is simply referred to as Alloy-P-10000.

[0111] The hydrogen absorption kinetic test results of Alloy-P-10000 are as Figure 10 shown. Under the condition of G-C10000 atmosphere, at a hydrogen absorption temperature of 300 °C, a hydrogen absorption pressure of 3 MPa, and a hydrogen absorption time of 100 min, the maximum hydrogen absorption capacity is 3.83 wt.%.

[0112] Furthermore, under the same conditions, when the number of cycles is 18, the maximum hydrogen absorption is 1.63 wt.%. The test results show that Alloy-A has good cycle stability in a poisoning atmosphere with a similar concentration.

[0113] It can be demonstrated by Comparative Example 3 that Alloy-A alloy can maintain good cycle stability in a high-concentration poisoning atmosphere.

Claims

1. A Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration performance, characterized in that: The composition of Mg-Ni-Nd hydrogen storage alloy is Nd4Mg 80 Ni8, Mg and Mg2Ni phases are activated by hydrogen absorption and desorption and then decomposed into Mg, Mg2Ni, NdH 2.61 Mutually.

2. The Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration performance according to claim 1, characterized in that: The content of Mg is 85-90%, the content of Ni is 6-10%, and the content of Nd is 2-5%.

3. A simulated poisoning treatment and poisoning regeneration method for a Mg-Ni-Nd hydrogen storage alloy, characterized in that: The method of simulating poisoning treatment is as follows: first, under the conditions of poisoning atmosphere, the hydrogen absorption temperature is 300°C, the hydrogen absorption pressure is 3MPa, and the hydrogen absorption time is 60min, the activated Mg-Ni-Nd alloy, referred to as Alloy-A, is subjected to a hydrogen absorption test; then, under vacuum conditions, the hydrogen desorption temperature is 300°C, and the hydrogen desorption time is 60min, a hydrogen desorption test is conducted, and a simulated poisoning treatment is completed; finally, the poisoning treatment operation is repeated until the hydrogen storage performance reaches a stable state, and the poisoned Mg-Ni-Nd alloy, referred to as Alloy-P, is obtained; The poisoning atmosphere is a mixture of CO2 and H2; The poisoning regeneration method is as follows: first, under the conditions of regeneration atmosphere, the hydrogen absorption temperature is 300°C, the suction pressure is 3MPa, and the hydrogen absorption time is 120min, the Alloy-P is subjected to a hydrogen absorption test, and then, under vacuum conditions, the hydrogen desorption temperature is 300°C, and the hydrogen desorption time is 120min, a hydrogen desorption test is carried out, and the poisoning regeneration of the Mg-Ni-Nd hydrogen storage alloy can be completed once, and the regenerated ecological Mg-Ni-Nd alloy is obtained, which is referred to as Alloy-R. The regeneration atmosphere is pure H2 atmosphere.

4. The Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration performance according to claim 1, characterized in that: When used as a hydrogen storage alloy, under the conditions of pure H2 atmosphere, hydrogen absorption temperature of 300°C, hydrogen absorption pressure of 3MPa, and hydrogen absorption time of 30min, the maximum hydrogen absorption amount is greater than 5.30wt.%.

5. The Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration performance according to claim 1, characterized in that: When used as a poison-resistant hydrogen storage alloy, under the conditions of a poisoning atmosphere, where the volume fraction of CO2 is 0.01%, the hydrogen absorption temperature is 300°C, the hydrogen absorption pressure is 3MPa, the number of cycles is greater than 300 times, and the hydrogen absorption time is 20 minutes, the maximum hydrogen absorption amount is greater than 5.0wt.; The CO2 concentration in the poisoned atmosphere condition is of the same order of magnitude as the CO2 concentration in the air.

6. The Mg-Ni-Nd hydrogen storage alloy with anti-poisoning and regeneration performance according to claim 1, characterized in that: When used as a renewable hydrogen storage alloy, under pure H2 atmosphere, the hydrogen absorption temperature is 300℃ and the hydrogen absorption pressure is 3MPa. When the poisoning regeneration times is 1, the hydrogen absorption time is 60min, the maximum hydrogen absorption amount is greater than 4.0wt.%, and the hydrogen absorption amount is restored to be greater than 80% of the initial hydrogen absorption amount; When the poisoning regeneration times are 2 times, the maximum hydrogen absorption amount can be reached after 30 minutes of hydrogen absorption time. The maximum hydrogen absorption amount is greater than 5.2wt.%, and the hydrogen absorption amount recovery is greater than 95% of the initial hydrogen absorption amount.

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