Rare earth TiFe hydrogen storage alloy material with poisoning resistance and preparation and regeneration method thereof

Abstract

The invention relates to a rare earth TiFe hydrogen storage alloy material with anti-poisoning capacity and a preparation and regeneration method thereof, belongs to the technical field of solid hydrogen storage materials, and solves the problems that in the prior art, rare earth TiFe hydrogen storage alloy is prone to poisoning by impurity gas, then hydrogen storage dynamics and capacity are affected, regeneration is difficult after poisoning, and the like. The invention provides a preparation method of a rare earth TiFe hydrogen storage alloy material with poison resistance. The preparation method comprises the following steps: crushing, screening, pickling, fluorinating, coating and drying a hydrogen storage alloy to obtain the hydrogen storage alloy material with poison resistance. The hydrogen storage alloy material has good anti-poisoning performance, poisoning of the hydrogen storage alloy caused by impurity gases such as CO, CO2 and O2 can be effectively blocked, and after 50 times of anti-poisoning circulation are carried out under the mixed gas condition, the hydrogen storage capacity retention rate is larger than or equal to 80%; the material can be regenerated at relatively low temperature and pressure, and the hydrogen storage capacity after regeneration can be recovered to 96.5% or above of the initial capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state hydrogen storage materials, and particularly to a rare-earth TiFe hydrogen storage alloy material with anti-poisoning ability and its preparation and regeneration methods. Background Art

[0002] In the research of solid-state hydrogen storage materials, TiFe hydrogen storage alloy has received extensive attention due to its advantages of large hydrogen storage capacity (theoretical maximum hydrogen storage capacity of 1.86 wt.%) and hydrogen absorption and desorption at room temperature. In recent years, after being modified by rare-earth element substitution, the formed rare-earth TiFe-based hydrogen storage alloy overcomes the problem that this type of material needs to complete the first activation hydrogen absorption at high temperature and high hydrogen pressure, making the application of this type of material easier.

[0003] Rare-earth TiFe hydrogen storage alloy faces an important challenge in practical applications - poisoning. The poisoning phenomenon refers to the reaction of the hydrogen storage alloy with impurity gases other than hydrogen in the environment, such as CO, CO2, O2, etc., resulting in a significant decline in its hydrogen storage capacity, such as hydrogen storage capacity and hydrogen absorption and desorption rate. However, during the actual use of the hydrogen storage alloy, due to the leakage of the hydrogen storage device, pollutants in the environmental atmosphere, and impurities in the gas transportation process, the hydrogen storage alloy will inevitably come into contact with various impurity gases. The existence of the poisoning problem poses a serious threat to the long-term use and performance stability of the rare-earth TiFe alloy.

[0004] Existing anti-poisoning treatment methods for hydrogen storage alloys often rely on alloy composition optimization and surface modification of the alloy by an external protective layer. These methods may be effective in the initial stage of the hydrogen absorption and desorption cycle process, but as the usage period extends, the alloy will still undergo irreversible decline in hydrogen storage performance, such as capacity attenuation and slowdown of hydrogen absorption and desorption rate.

[0005] Therefore, aiming at the poisoning problem caused by contact with impurity gases during the long-term use of hydrogen storage alloys, it is urgent to propose a new anti-poisoning treatment method to effectively improve the anti-poisoning ability of hydrogen storage alloys and extend their service life; and provide an effective regeneration technology after the alloy is poisoned to restore its hydrogen storage performance and ensure long-term stability and safety. Summary of the Invention

[0006] In view of the above analysis, the embodiments of the present invention aim to provide a rare-earth TiFe hydrogen storage alloy material with anti-poisoning ability and its preparation and regeneration methods to solve at least one of the problems such as poor anti-poisoning performance of existing rare-earth TiFe hydrogen storage alloy materials, existing anti-poisoning treatment methods reducing the performance of hydrogen storage materials and being unable to maintain the long-term cyclic use performance of hydrogen storage materials.

[0007] The present invention provides a preparation method of a rare-earth TiFe hydrogen storage alloy material with anti-poisoning ability, including the following steps:

[0008] S1: Crush and screen the rare earth TiFe hydrogen storage alloy to obtain alloy powder with an appropriate particle size;

[0009] S2: Pickle the alloy powder and then wash it with water after pickling;

[0010] S3: Add the alloy powder after water washing to a fluoride solution for fluorination treatment. After the reaction is completed, remove the excess fluoride solution and dry it;

[0011] S4: Mix the alloy powder after fluorination treatment with the polymer evenly and add an organic solvent until the polymer is completely dissolved to obtain a mixture of the polymer solution and the alloy powder, and complete the preliminary coating of the alloy powder by the polymer;

[0012] S5: After the preliminary coating is completed, dry the mixture to obtain a rare earth TiFe hydrogen storage alloy material with anti-poisoning ability;

[0013] Among them, the polymer described in S4 is a polymer material with hydrogen selective permeability.

[0014] Specifically, the rare earth TiFe hydrogen storage alloy is one or more of La-TiFe hydrogen storage alloy, Y-TiFe hydrogen storage alloy, and Pr-TiFe hydrogen storage alloy.

[0015] Specifically, the particle size of the alloy powder in S1 is 100-150 mesh.

[0016] Specifically, the specific operation of pickling in S2 is as follows:

[0017] Prepare a dilute hydrochloric acid solution with a concentration of 1 mol / L to 2 mol / L. The dilute hydrochloric acid can ensure that the rare earth elements dissolve slowly, avoid excessive loss of the rare earth phase, and maintain the stability of the alloy composition. Add the dilute hydrochloric acid solution to the rare earth TiFe hydrogen storage alloy powder to ensure that the alloy powder is completely immersed in the dilute hydrochloric acid solution, stir and keep the soaking time for 5-10 minutes, and wash the alloy powder with water until the pH value of the washing liquid ≥ 6.5.

[0018] Specifically, the specific operation of fluorination treatment in S3 is as follows:

[0019] Prepare a fluoride solution with a concentration of 0.05 mol / L to 0.2 mol / L. Add the rare earth TiFe hydrogen storage alloy powder after pickling to the fluoride solution, and the alloy powder should be completely covered by the fluoride solution. Stir continuously for 30 minutes to 1 hour;

[0020] After the reaction is completed, use suction filtration to remove the excess fluoride solution on the surface of the alloy powder, and then place the alloy powder after suction filtration in a vacuum drying oven at 80-100 °C for drying treatment.

[0021] Specifically, the fluoride is one or more of nickel fluoride, sodium fluoride, and potassium fluoride.

[0022] Specifically, the polymer in S4 is one or more of polymethyl methacrylate, epoxy resin, polyamide, and polyether ether ketone;

[0023] The mass ratio of the alloy powder to the polymer is 85 - 95:5 - 15.

[0024] The present invention also provides a rare earth TiFe hydrogen storage alloy material with anti - poisoning ability. The alloy material is prepared by the above - mentioned preparation method, and the surface of the hydrogen storage alloy material has a polymer coating layer with a thickness of 0.5 - 1.5 μm.

[0025] Furthermore, after the hydrogen storage alloy material undergoes 50 anti - poisoning cycles under the conditions of a mixed gas of 600 ppm CO + 300 ppm CO2 + 100 ppm O2 with the rest being hydrogen and a pressure of 3 MPa, the capacity retention rate is ≥80.5%.

[0026] The present invention also provides a regeneration method for the above - mentioned hydrogen storage alloy material. The specific process is as follows:

[0027] Under the condition of a temperature of 100 - 200 °C, regeneration treatment is carried out with high - purity hydrogen at 2 - 5 MPa, and the treatment time is 0.5 - 1 h;

[0028] Among them, the purity of the high - purity hydrogen is ≥99.99%, and after the regeneration treatment, the hydrogen storage capacity of the hydrogen storage alloy material can be restored to more than 96.5% of the initial capacity.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] 1. The anti - poisoning treatment method provided by the present invention has little influence on the maximum hydrogen storage capacity of the hydrogen storage material. The combination of the polymer coating layer and the hydrogen storage alloy powder is firm, the anti - poisoning ability is significantly improved, and the service life is significantly extended (it still has a high capacity after 50 anti - poisoning cycles and can be regenerated).

[0031] When attempting to form a protective layer on the surface of hydrogen storage alloy powder using a similar polymer, due to the poor adhesion between the surface of the hydrogen storage alloy and the polymer with hydrogen selective permeability, in order to achieve effective adhesion and avoid detachment, it is necessary to use small particle hydrogen storage alloy powder and add a large amount of polymer (the polymer addition amount even reaches more than 50%), which is equivalent to forming a thick outer shell on the surface of the hydrogen storage alloy powder. Although it has a certain anti-poisoning effect, it significantly reduces the maximum hydrogen storage capacity of the material (the polymer outer shell does not generate hydrogen storage capacity), and although the outer shell has the properties of anti-poisoning / selective permeation, due to the too thick outer shell, it also significantly reduces the kinetic performance of hydrogen.

[0032] Based on the significant defects of the above method, the present invention selects larger particle hydrogen storage alloy powder. When estimating the powder as nearly spherical, when the polymer addition ratio (mass or volume) is certain, the larger the particle size of the hydrogen storage alloy powder, the thinner the formed protective layer. Particularly preferably, the present invention selects hydrogen storage alloy powder with a mesh size of 100 - 150, and the thickness of the protective layer is about 0.5 - 1.5 μm, which has little influence on the hydrogen absorption and desorption kinetic performance.

[0033] The present invention adopts an acid pickling process. On the one hand, it removes the oxide layer on the surface of the hydrogen storage alloy, which helps to improve the hydrogen absorption and desorption performance and adhesion, and also helps the subsequent fluorination treatment to be more sufficient and uniform; on the other hand, a small amount of Ti / Fe / rare earth elements dissolve in the acid solution, which can also play a certain surface etching role and is also beneficial to improving the adhesion of the subsequent fluoride layer.

[0034] After acid pickling, a fluorination treatment process is adopted. Since acid pickling exposes a large number of fresh surfaces of the alloy, the fluoride will form a TiF3 / FeF2 network structure with the surface Ti / Fe, which serves as a stable intermediate layer to adjust the surface chemical state, making the subsequent coating / layer tightly combined with the substrate, thereby reducing coating defects; in addition, the fluoride in the network structure also serves as a protective barrier to a certain extent to reduce the influence of impurity gases and helps to improve the anti-poisoning performance.

[0035] Since the present invention pre-treats the alloy powder through acid pickling and fluorination steps, the polymer addition amount during the coating process is significantly reduced (the mass ratio of the alloy powder to the polymer is 85 - 95:5 - 15), but the bonding stability of the coating layer is even improved. Combined with the fluoride in the network structure, good anti-poisoning performance can be achieved.

[0036] After undergoing the above anti-poisoning treatment, the hydrogen storage alloy material was subjected to 50 anti-poisoning cycles under the conditions of a mixed gas of 600 ppm CO + 300 ppm CO2 + 100 ppm O2 with the rest being hydrogen and a pressure of 3 MPa, and the capacity retention rate was ≥ 80.5%; in addition, it was able to maintain the hydrogen storage capacity in hydrogen mixed with various impurity gases, achieving comprehensive protection, avoiding the performance degradation of the alloy caused by the poisoning of impurity gases during multiple hydrogen absorption and desorption cycles, thereby extending the service life of the hydrogen storage alloy.

[0037] 2. The hydrogen storage alloy material provided by the present invention has good hydrogen absorption and desorption performance and a high maximum hydrogen storage capacity. Since the highest proportion of the polymer added in the present invention is only 15%, and the particle size of the hydrogen storage alloy powder is relatively large, the coating layer is very thin. In addition, the pickling process removes the oxide layer on the surface of the hydrogen storage alloy, which also helps to improve the hydrogen absorption and desorption performance; based on the above characteristics, the coating layer has little influence on the hydrogen absorption and desorption performance of the hydrogen storage alloy material. Even when using the highest polymer addition amount, the maximum hydrogen storage capacity can still be maintained above 1.54 wt.%.

[0038] 3. The regeneration method provided by the present invention has good effects, and the required treatment pressure, temperature, and treatment time are significantly reduced / shortened. Since the hydrogen storage alloy material provided by the present invention has good anti-poisoning performance, the binding energy of poisoning gases such as CO, CO2, and O2 on the alloy surface is reduced due to the presence of the coating layer polymer and the network fluoride, and a lower temperature can provide sufficient gas surface dissociation energy to re-expose the active sites for hydrogen to enter.

[0039] Under the condition of a temperature of 100 - 200 °C, regeneration treatment is carried out with high-purity hydrogen at 2 - 5 MPa, and the treatment time is 0.5 - 1 h; wherein, the purity of the high-purity hydrogen is ≥ 99.99%, and the hydrogen storage capacity of the hydrogen storage alloy material after regeneration treatment can be restored to more than 96.5% of the initial capacity.

[0040] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be made obvious from the description, or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained through the content specifically pointed out in the description and the drawings. Description of the Drawings

[0041] The drawings are only for the purpose of showing specific embodiments and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs represent the same components.

[0042] Figure 1 It is a SEM morphology photo of the rare earth TiFe hydrogen storage alloy material after coating treatment in Example 1;

[0043] Figure 2 Hydrogen absorption curves of the maximum hydrogen storage capacity for Examples 1 to 3 and Comparative Examples 1 to 3, and hydrogen absorption curves after 50 cycles in the poisoning gas;

[0044] Figure 3 Regenerated hydrogen absorption curves for Example 2 and Comparative Examples 4 to 6. Detailed implementation manners

[0045] The preferred embodiments of the present invention will be specifically described below in conjunction with the accompanying drawings. The accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principles of the present invention, rather than to limit the scope of the present invention.

[0046] When attempting to form a protective layer on the surface of the hydrogen storage alloy powder using a similar polymer, due to the poor adhesion between the surface of the hydrogen storage alloy and the polymer with hydrogen gas selective permeability, in order to achieve effective adhesion and avoid shedding, it is necessary to use small particle-sized hydrogen storage alloy powder and add a large amount of polymer (the polymer addition amount even reaches more than 50%), which is equivalent to forming a thick outer shell on the surface of the hydrogen storage alloy powder. Although it has a certain anti-poisoning effect, it significantly reduces the maximum hydrogen storage capacity of the material (the polymer outer shell does not generate hydrogen storage capacity), and although the outer shell has the performance of anti-poisoning / selective permeation, due to the too thick outer shell, it also significantly reduces the kinetic performance of hydrogen gas.

[0047] The present invention provides a preparation method of a TiFe hydrogen storage alloy material with anti-poisoning ability, including the following steps:

[0048] S1: Crushing and sieving the rare earth TiFe hydrogen storage alloy to obtain alloy powder with an appropriate particle size;

[0049] S2: Pickling the alloy powder and then washing it with water after pickling;

[0050] S3: Adding the washed alloy powder to a fluoride solution for fluorination treatment, and removing the excess fluoride solution and drying after the reaction is completed;

[0051] S4: Mixing the fluorinated alloy powder and the polymer evenly and adding an organic solvent until the polymer is completely dissolved to obtain a mixture of a polymer solution and alloy powder, and completing the preliminary coating of the alloy powder by the polymer;

[0052] S5: After the preliminary coating is completed, drying the mixture to obtain a rare earth TiFe hydrogen storage alloy material with anti-poisoning ability;

[0053] The hydrogen storage alloy material can be used in hydrogen fuel cell systems, industrial catalysis and gas purification, sensors and hydrogen isotope processing, etc., which contain impurity gases;

[0054] Among them, the polymer described in S4 is a polymer material with hydrogen selective permeability.

[0055] Specifically, the rare earth TiFe hydrogen storage alloy is one or more of La-TiFe, Y-TiFe, Pr-TiFe, and hydrogen storage alloys mixed with multiple rare earth elements. The TiFe alloy containing La, Y, Pr, and mixed rare earth elements can form more defect areas on the surface, which is suitable for subsequent pickling and fluorination steps. It can efficiently remove the surface oxide layer while retaining the active sites in the rare earth enrichment area, forming a dense fluoride layer. It should be noted that when the hydrogen storage alloy contains multiple rare earth elements at the same time, it can be classified as any rare earth TiFe hydrogen storage alloy.

[0056] Specifically, the particle size of the alloy powder in S1 is 100-150 mesh. When the alloy powder particles are less than 150 mesh, more surface is exposed to impurity gases, and the surface activity becomes poor, resulting in a slower initial hydrogen absorption rate of the alloy and difficulty in activation. When the alloy powder particles are larger than 100 mesh, the larger particles are difficult to be uniformly coated, and the thickness of the formed coating film is uneven. The coating layer is prone to cracking during hydrogen absorption and desorption due to uneven stress.

[0057] Specifically, the specific operation of pickling in S2 is as follows:

[0058] Prepare a dilute hydrochloric acid solution with a concentration of 1mol / L - 2mol / L. The dilute hydrochloric acid can ensure slow dissolution of rare earth elements, avoid excessive loss of rare earth phases, and maintain the stability of the alloy composition. Add the dilute hydrochloric acid solution to the rare earth TiFe hydrogen storage alloy powder to ensure that the alloy powder is completely immersed in the dilute hydrochloric acid solution. Stir and keep the soaking time for 5 - 10 minutes. Rinse the alloy powder with water until the pH value of the rinsing solution ≥ 6.5, preferably pH = 7. Through pickling, the oxides naturally formed on the surface of the rare earth TiFe alloy are dissolved, exposing the fresh Ti / Fe / rare earth metal surface, activating the reaction activity, making the subsequent fluorination treatment more sufficient and uniform, and reducing the influence of inert oxides on the alloy surface on the hydrogen storage performance. When the acid concentration is higher than 2mol / L, the rare earth elements dissolve in the acid, resulting in poor hydrogen absorption and desorption activation performance of the alloy. When the acid concentration is lower than 1mol / L, residual oxides remain on the alloy surface, and only local reactions can occur during subsequent fluorination treatment, resulting in incomplete coverage of the fluoride layer.

[0059] Specifically, the specific operation of fluorination treatment in S3 is as follows:

[0060] Prepare a fluoride solution with a concentration of 0.05mol / L - 0.2mol / L. Add the pickled rare earth TiFe hydrogen storage alloy powder to the fluoride solution, and the alloy powder should be completely covered by the fluoride solution. Stir continuously for 30 minutes - 1 hour;

[0061] After the reaction is completed, the excess fluoride solution on the surface of the alloy powder is removed by suction filtration, and then the alloy powder after suction filtration is placed in a vacuum drying oven at 80-100 °C for drying treatment.

[0062] Since pickling exposes a large number of fresh surfaces of the alloy, fluoride will form a TiF3 / FeF2 network structure with the surface Ti / Fe, which serves as a stable intermediate layer to adjust the surface chemical state, making the coating adhere tightly to the substrate, thereby reducing coating defects. When the fluoride solution is higher than 0.2 mol / L, an overly thick fluoride layer will be formed, resulting in significant mechanical mismatch with the coated polymer layer. When the fluoride solution is lower than 0.05 mol / L, the coverage rate of the fluoride layer is insufficient, and the polymer coating layer will have shrinkage defects, leading to a decline in the anti-poisoning ability. In addition, the fluoride in the network structure also serves as a protective barrier to a certain extent, reducing the influence of impurity gases.

[0063] Specifically, the fluoride is one or more of nickel fluoride, sodium fluoride, and potassium fluoride. The above-mentioned fluorides can all stably release F - , reacting with the active elements on the metal surface to form fluorides. The concentration of the fluoride solution is controlled at 0.05-0.2 mol / L. If the concentration of the fluoride solution is too high, it will over-etch the hydrogen storage alloy substrate, resulting in a decline in hydrogen storage performance.

[0064] Specifically, the specific process of step S4 is as follows: After the rare earth TiFe hydrogen storage alloy powder is fluorinated, it is mechanically mixed with the polymer until evenly distributed, and then an organic solvent is added until the polymer is completely dissolved to form a mixture with the alloy. The mixture is mechanically stirred and / or ultrasonically treated for 30-60 min until the color of the suspension is uniform, ensuring that the alloy powder is evenly distributed in the polymer solution.

[0065] Specifically, the polymer in S4 is one or more of polymethyl methacrylate, epoxy resin, polyamide, and polyether ether ketone; the above-mentioned several polymers all have H2 selective permeability (especially for CO, CO2, and O2), and the separation coefficients are as follows:

[0066] Polymethyl methacrylate PMMA (H2 / CO selective permeability: ~34, H2 / CO2 selective permeability: ~24, H2 / O2 selective permeability: ~43), epoxy resin (EP) (H2 / CO selective permeability: ~18, H2 / CO2 selectivity: ~58, H2 / O2 selectivity: ~12), polyamide (PA) (H2 / CO selective permeability: ~67, H2 / CO2 selectivity: ~32, H2 / O2 selectivity: ~160), and polyether ether ketone PEEK (H2 / CO selective permeability: ~29, H2 / CO2 selectivity: ~12.5, H2 / O2 selectivity: ~35).

[0067] Furthermore, different polymers can be selected according to the composition of impurity gases in the specific use environment. For example, in an environment with oxygen and carbon monoxide as the main impurity gases, polyamide is more suitable; in an impurity gas environment with a higher carbon dioxide content, epoxy resin is more appropriate. In addition, a comprehensive selection can also be made according to the usage requirements in combination with the economic cost.

[0068] The mass ratio of the alloy powder to the polymer is 85-95:5-15. The function of the coating material is to isolate macromolecular impurity gases when the alloy absorbs hydrogen. A too thin coating layer is not sufficient to protect the alloy from poisoning, while a too thick coating layer will hinder the entry of hydrogen atoms, resulting in a decrease in the hydrogen absorption and desorption rate and a reduction in the hydrogen storage capacity. The alloy powder particle size selected in the present invention is 100-150 mesh. By adding a small amount of polymer, a coating layer with a thickness of 0.5-1.5 μm can be obtained, which can minimize the loss of hydrogen storage capacity while meeting the requirements of high anti-poisoning.

[0069] Preferably, in step S5, the drying process is as follows: Place the vessel containing the mixture of alloy powder and polymer solution in a vacuum drying oven. Considering the solvent evaporation temperature and the usage temperature of different polymers, set the drying temperature to 60-100 °C for drying. After complete drying, a coated rare earth TiFe-based hydrogen storage alloy with anti-poisoning ability is obtained.

[0070] The present invention also provides a rare earth TiFe hydrogen storage alloy material with anti-poisoning ability. The alloy material is prepared by the above preparation method, and the surface of the hydrogen storage alloy material has a polymer coating layer with a thickness of 0.5-1.5 μm.

[0071] Furthermore, after 50 anti-poisoning cycles under the conditions of a mixed gas of 600 ppm CO + 300 ppm CO2 + 100 ppm O2 + the rest being hydrogen and a pressure of 3 MPa, the capacity retention rate of the hydrogen storage alloy material is ≥ 80.5%.

[0072] The present invention also provides a regeneration method for the above hydrogen storage alloy material. The specific process is as follows:

[0073] Under the condition of a temperature of 100-200 °C, perform regeneration treatment with high-purity hydrogen at a pressure of 2-5 MPa for a treatment time of 0.5-1 h;

[0074] Among them, the purity of the high-purity hydrogen is ≥ 99.99%. After the regeneration treatment, the hydrogen storage capacity of the hydrogen storage alloy material can be restored to more than 96.5% of the initial capacity.

[0075] The regeneration method provided by the present invention has good effects, and the required treatment pressure, temperature and treatment time are significantly reduced / shortened. Due to the good poisoning resistance of the hydrogen storage alloy material provided by the present invention, the binding energy of poisoning gases such as CO, CO2 and O2 on the alloy surface is reduced due to the presence of the coating polymer and the network fluoride, and a lower temperature can provide sufficient gas surface dissociation energy to re-expose the active sites for hydrogen entry.

[0076] Example 1

[0077] The prepared rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy was mechanically crushed and then sieved through 100 - 150 meshes. The collected alloy powder of 100 - 150 meshes was immersed in 1 mol / L dilute hydrochloric acid. After 10 minutes, it was rinsed with deionized water until the pH = 7. Then, the acid-treated hydrogen storage alloy was kept in 0.1 mol / L sodium fluoride solution for 30 min for fluorination treatment. After the fluorination treatment was completed, suction filtration was carried out to remove the fluorination solution on the alloy surface, and the alloy powder was vacuum dried at 100 °C.

[0078] The fluorinated alloy powder and PMMA powder were weighed according to the mass ratio of 95:5 and placed in a glass container. After mechanical stirring and mixing evenly, tetrahydrofuran solution was added until the polymer was completely dissolved. The mixture was continuously mechanically stirred and ultrasonically treated for 30 min to make the mixture uniform.

[0079] The uniformly mixed mixture was placed in a vacuum drying oven, and the temperature was set at 100 °C. After complete drying, the rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy coated with PMMA - 5 wt.% was obtained, and the thickness of the coating layer was about 0.5 μm.

[0080] The sample was placed in a Sieverts-type device for poisoning resistance performance testing. The gas used was hydrogen containing 600 ppm CO + 300 ppm CO2 + 100 ppm O2. The pressure of the mixed gas was adjusted to 3 MPa, and the hydrogen storage capacity was obtained by measuring the pressure change value. After 50 anti-poisoning cycles, the hydrogen storage capacity changed from 1.73 wt.% to 1.40 wt.%, and the capacity retention rate was 80.9%.

[0081] The poisoned hydrogen storage alloy was subjected to regeneration treatment. The temperature was set at 100 °C, and high-purity hydrogen of 5 MPa was charged. After 1 hour, the regeneration treatment was completed. The above anti-poisoning test was carried out, and the hydrogen storage capacity was restored to 1.70 wt.%, which was 97.1% of the original maximum hydrogen storage capacity.

[0082] Example 2

[0083] The obtained rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy was mechanically crushed and then screened through 100 - 150 mesh. The collected alloy powder of 100 - 150 mesh was immersed in 1 mol / L dilute hydrochloric acid. After maintaining for 10 minutes, it was rinsed with deionized water until the pH = 7. Then, the acid - treated hydrogen storage alloy was maintained in 0.1 mol / L sodium fluoride solution for 30 min for fluorination treatment. After the fluorination treatment was completed, suction filtration was carried out to remove the fluorination solution on the alloy surface, and the alloy powder was vacuum - dried at 100 °C.

[0084] The fluorinated - treated alloy powder and PMMA powder were weighed according to a mass ratio of 90:10 and placed in a glass container. The mixture was continuously mechanically stirred and ultrasonically treated for 45 min, and then tetrahydrofuran solution was added until the polymer was completely dissolved. The mixture was ultrasonically treated for another 30 min to make the mixture homogeneous.

[0085] The homogeneous mixture was placed in a vacuum drying oven, and the temperature was set at 100 °C. After complete drying, the rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy coated with PMMA - 10wt.% was obtained, and the thickness of the coating layer was about 1.0 μm.

[0086] The sample was placed in a Sieverts - type device for anti - poisoning performance testing. The gas used was hydrogen containing 600 ppm CO + 300 ppm CO2+100 ppm O2. The pressure of the mixed gas was adjusted to 3 MPa, and the hydrogen storage capacity was obtained by measuring the pressure change value. After 50 anti - poisoning cycles, the hydrogen storage capacity changed from 1.65 wt.% to 1.35 wt.%, and the capacity retention rate was 81.8%.

[0087] The poisoned hydrogen storage alloy was regenerated. The temperature was set at 100 °C, and high - purity hydrogen with a pressure of 3 MPa was charged. After 1 hour, the regeneration treatment was completed. After performing the above anti - poisoning test, the hydrogen storage capacity recovered to 1.63 wt.%, which was 98.8% of the original maximum hydrogen storage capacity.

[0088] Example 3

[0089] The obtained rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy was mechanically crushed and then screened through 100 - 150 mesh. The collected alloy powder of 100 - 150 mesh was immersed in 1 mol / L dilute hydrochloric acid. After maintaining for 10 minutes, it was rinsed with deionized water until the pH = 7. Then, the acid - treated hydrogen storage alloy was maintained in 0.1 mol / L sodium fluoride solution for 30 min for fluorination treatment. After the fluorination treatment was completed, suction filtration was carried out to remove the fluorination solution on the alloy surface, and the alloy powder was vacuum - dried at 100 °C.

[0090] Weigh the fluorinated alloy powder and PMMA powder according to a mass ratio of 85:15, and place them in a glass container. After mechanical stirring and mixing evenly, add tetrahydrofuran solution until the polymer is completely dissolved. Continuously mechanically stir and ultrasonically treat the mixture for 60 min to make the mixture uniform.

[0091] Place the evenly mixed mixture in a vacuum drying oven, set the temperature to 100 °C, and after complete drying, a rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy coated with 15 wt.% PMMA is obtained, and the thickness of the coating layer is about 1.5 μm.

[0092] Place the sample in a Sieverts-type device for anti-poisoning performance testing. The gas used is hydrogen containing 600 ppm CO + 300 ppm CO2 + 100 ppm O2. Adjust the pressure of the mixed gas to 3 MPa, and obtain the hydrogen storage capacity by measuring the pressure change value. After 50 anti-poisoning cycles, the hydrogen storage capacity changes from 1.55 wt.% to 1.35 wt.%, and the capacity retention rate is 87.1%.

[0093] Regenerate the poisoned hydrogen storage alloy. Set the temperature to 150 °C, and charge 2 MPa of high-purity hydrogen. After 1 hour, the regeneration treatment is completed. Perform the above anti-poisoning test, and the hydrogen storage capacity is restored to 1.53 wt.%, which is 98.7% of the original maximum hydrogen storage capacity.

[0094] Example 4

[0095] Mechanically crush the prepared rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy and then screen it through 100 - 150 mesh. Immerse the collected 100 - 150 mesh alloy powder in 2 mol / L dilute hydrochloric acid for 5 minutes, and then rinse it with deionized water until the pH = 7. Then, keep the acid-treated hydrogen storage alloy in 0.1 mol / L nickel fluoride solution for 1 h for fluorination treatment. After the fluorination treatment is completed, perform suction filtration to remove the fluorination solution on the surface of the alloy, and vacuum dry the alloy powder at 100 °C.

[0096] Weigh the fluorinated alloy powder and PEEK according to a mass ratio of 90:10, and place them in a glass container. Continuously mechanically stir and ultrasonically treat the mixture for 30 min, add chloroform solution until the polymer is completely dissolved, and continuously stir and ultrasonically treat the mixture to make the mixture uniform.

[0097] Place the well - mixed mixture in a vacuum drying oven, set the temperature at 60 °C. After complete drying, a rare - earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen - storage alloy coated with 10 wt.% PEEK is obtained, and the thickness of the coating layer is about 1.0 μm.

[0098] Place the sample in a Sieverts - type device for anti - poisoning performance testing. The gas used is hydrogen containing 600 ppm CO + 300 ppm CO2+100 ppm O2. Adjust the pressure of the mixed gas to 3 MPa, and obtain the hydrogen - storage capacity by measuring the pressure change value. After 50 anti - poisoning cycles, the hydrogen - storage capacity changes from 1.63 wt.% to 1.34 wt.%, and the capacity retention rate is 82.2%.

[0099] Regenerate the poisoned hydrogen - storage alloy. Set the temperature at 200 °C, and charge 2 MPa of high - purity hydrogen. After 1 hour, the regeneration treatment is completed. Conduct the above - mentioned anti - poisoning test, and the hydrogen - storage capacity is restored to 1.60 wt.%, which is 98.2% of the original maximum hydrogen - storage capacity.

[0100] Example 5

[0101] Mechanically crush the prepared rare - earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen - storage alloy and screen it through 100 - 150 mesh. Immerse the collected 100 - 150 mesh alloy powder in 1 mol / L dilute hydrochloric acid for 10 minutes, then rinse it with deionized water until the pH = 7. Then, keep the acid - treated hydrogen - storage alloy in 0.1 mol / L potassium fluoride solution for 1 h for fluorination treatment. After the fluorination treatment is completed, perform suction filtration to remove the fluorination solution on the surface of the alloy, and vacuum - dry the alloy powder at 100 °C.

[0102] Weigh the fluorinated - treated alloy powder and EP according to the mass ratio of 85:15, and place them in a glass container. After mechanically stirring and mixing evenly, add acetone solution until the polymer is completely dissolved, and continuously stir and ultrasonically treat the mixture for 45 min to make the mixture uniform.

[0103] Place the well - mixed mixture in a vacuum drying oven, set the temperature at 80 °C. After complete drying, a rare - earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen - storage alloy coated with 15 wt.% EP is obtained, and the thickness of the coating layer is about 1.5 μm.

[0104] The sample was placed in a Sieverts-type device for anti-poisoning performance testing. The gas used was hydrogen containing 600 ppm CO + 300 ppm CO2 + 100 ppm O2. The pressure of the mixed gas was adjusted to 3 MPa, and the hydrogen storage capacity was obtained by measuring the pressure change value. After 50 anti-poisoning cycles, the hydrogen storage capacity changed from 1.54 wt.% to 1.36 wt.%, and the capacity retention rate was 88.3%.

[0105] The poisoned hydrogen storage alloy was regenerated. The set temperature was 150 °C, and high-purity hydrogen at 4 MPa was charged. After 1 hour, the regeneration treatment was completed. The above anti-poisoning test was carried out, and the hydrogen storage capacity was restored to 1.51 wt.%, which was 98.1% of the original maximum hydrogen storage capacity.

[0106] Example 6

[0107] The prepared rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy was mechanically crushed and sieved through 100 - 150 mesh. The collected alloy powder of 100 - 150 mesh was immersed in 2 mol / L dilute hydrochloric acid. After 5 minutes, it was rinsed with deionized water until the pH = 7. Then, the acid-treated hydrogen storage alloy was kept in 0.1 mol / L sodium fluoride solution for 1 h for fluorination treatment. After the fluorination treatment was completed, suction filtration was carried out to remove the fluorination solution on the surface of the alloy, and the alloy powder was vacuum dried at 100 °C.

[0108] The fluorinated alloy powder and PA were weighed according to a mass ratio of 95:5 and placed in a glass container. The mixture was continuously mechanically stirred and ultrasonically treated for 30 min. Acetone solution was added until the polymer was completely dissolved, and the mixture was continuously stirred and ultrasonically treated to make the mixture uniform.

[0109] The uniformly mixed mixture was placed in a vacuum drying oven, and the set temperature was 100 °C. After complete drying, the rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy coated with PA - 5 wt.% was obtained, and the thickness of the coating layer was about 0.5 μm.

[0110] The sample was placed in a Sieverts-type device for anti-poisoning performance testing. The gas used was hydrogen containing 600 ppm CO + 300 ppm CO2 + 100 ppm O2. The pressure of the mixed gas was adjusted to 3 MPa, and the hydrogen storage capacity was obtained by measuring the pressure change value. After 50 anti-poisoning cycles, the hydrogen storage capacity changed from 1.71 wt.% to 1.41 wt.%, and the capacity retention rate was 82.5%.

[0111] The poisoned hydrogen storage alloy was regenerated at a set temperature of 100 °C by charging high-purity hydrogen at 5 MPa. After 1 hour, the regeneration process was completed. The above anti-poisoning test was carried out, and the hydrogen storage capacity recovered to 1.65 wt.%, which was 96.5% of the original maximum hydrogen storage capacity.

[0112] Comparative Example 1

[0113] The prepared rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy was mechanically crushed and sieved through 100 - 150 meshes.

[0114] The alloy was not subjected to the above acidification, fluorination, and surface coating treatments. The sample was directly placed in a Sieverts-type device for anti-poisoning performance testing. The gas used was hydrogen containing 600 ppm CO + 300 ppm CO2 + 100 ppm O2. The pressure of the mixed gas was adjusted to 3 MPa, and the hydrogen storage capacity was obtained by measuring the pressure change value. After 50 anti-poisoning cycles, the hydrogen storage capacity changed from 1.80 wt.% to 0.31 wt.%, and the capacity retention rate was 17.2%.

[0115] The poisoned hydrogen storage alloy was regenerated at a set temperature of 100 °C by charging high-purity hydrogen at 5 MPa. After 1 hour, the regeneration process was completed. The above anti-poisoning test was carried out, and the hydrogen storage capacity recovered to 1.00 wt.%, which was 55.6% of the original maximum hydrogen storage capacity.

[0116] Comparative Example 2

[0117] In this comparative example, the rare earth TiFe hydrogen storage alloy powder and PMMA were coated according to a mass ratio of 97:3, and other operations and parameters were the same as in Example 1. A rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy coated with 3 wt.% PMMA was obtained, and the coating thickness was about 0.3 μm.

[0118] After 50 anti-poisoning cycles, the hydrogen storage capacity of the sample changed from 1.75 wt.% to 0.60 wt.%, and the capacity retention rate was 34.3%. After regeneration treatment, the hydrogen storage capacity recovered to 1.22 wt.%, which was 69.7% of the original maximum hydrogen storage capacity.

[0119] Comparative Example 3

[0120] In this comparative example, the rare earth TiFe hydrogen storage alloy powder and PMMA were coated according to a mass ratio of 80:20, and other operations and parameters were the same as in Example 1. A rare earth (Ti, Y, La, Pr, Sm)(Fe, Mn, Ni, Cr, V) hydrogen storage alloy coated with 20 wt.% PMMA was obtained, and the coating thickness was about 2.0 μm.

[0121] After 50 anti-poisoning cycles, the hydrogen storage capacity of the sample changed from 1.47 wt.% to 1.29 wt.%, and the capacity retention rate was 87.8%. After regeneration treatment, the hydrogen storage capacity recovered to 1.45 wt.%, which was 98.6% of the original maximum hydrogen storage capacity.

[0122] Comparative Example 4

[0123] The regeneration treatment temperature of this comparative example was 250 °C, and other operations and parameters were the same as those in Example 2.

[0124] After 50 anti-poisoning cycles, the hydrogen storage capacity of the sample changed from 1.65 wt.% to 1.35 wt.%, and the capacity retention rate was 81.8%. After regeneration treatment, the hydrogen storage capacity recovered to 1.45 wt.%, which was 87.3% of the original maximum hydrogen storage capacity.

[0125] Comparative Example 5

[0126] The regeneration treatment temperature of this comparative example was 80 °C, and other operations and parameters were the same as those in Example 2.

[0127] After 50 anti-poisoning cycles, the hydrogen storage capacity of the sample changed from 1.65 wt.% to 1.35 wt.%, and the capacity retention rate was 81.8%. After regeneration treatment, the hydrogen storage capacity recovered to 1.38 wt.%, which was 83.6% of the original maximum hydrogen storage capacity.

[0128] Comparative Example 6

[0129] The regeneration treatment hydrogen pressure of this comparative example was 1 MPa, and other operations and parameters were the same as those in Example 2.

[0130] After 50 anti-poisoning cycles, the hydrogen storage capacity of the sample changed from 1.65 wt.% to 1.35 wt.%, and the capacity retention rate was 81.8%. After regeneration treatment, the hydrogen storage capacity recovered to 1.40 wt.%, which was 84.8% of the original maximum hydrogen storage capacity.

[0131] Table 1 Summary of hydrogen storage / regeneration performance of Examples 1-6 and Comparative Examples 1-6

[0132]

[0133]

[0134] As can be seen from Table 1 and Figure 1 、 2 and 3, Comparative Example 1 was not coated and had the maximum hydrogen storage capacity of 1.80 wt.% under high-purity hydrogen. However, after 50 cycles, the capacity remained only 0.31 wt.%, and the capacity retention rate was 17.2%.

[0135] Comparing Comparative Examples 1, 2, and 3, it can be seen that as the coating amount increases, the maximum hydrogen storage capacity of the alloy decreases, but the capacity retention rate after 50 cycles is greater than 80%. Continuing to increase the coating amount, it can be found from Comparative Example 3 that when the coating amount is 20 wt.%, the hydrogen storage capacity decreases to 1.47 wt.%, and the capacity retention rate after 50 cycles in the poisoning gas is similar to that of Example 3. Therefore, too high a coating amount is not conducive to further improving the anti-poisoning hydrogen storage performance of the alloy. And it can be seen from Comparative Example 2 that with a coating amount of 3 wt.%, the alloy still has a relatively high hydrogen storage capacity of 1.75 wt.% under high-purity hydrogen, but after 50 cycles, the capacity is only 0.60 wt.%, and the capacity retention rate is 34.3%. A small amount of coating cannot form a dense protective layer to hinder the poisoning effect of large-molecule gases on the alloy.

[0136] Comparing the regeneration performance of Example 2 with Comparative Examples 4, 5, and 6, it is found that Example 2 can be regenerated at 100 °C and a hydrogen pressure of 3 MPa in 1 h, and the capacity is restored to 1.63 wt.%, which is 98.8% of the original maximum hydrogen storage capacity. In Comparative Example 4, when the regeneration temperature is increased to 250 °C, the hydrogen storage capacity after regeneration is 1.47 wt.%, which is only 87.3% of the original capacity. This is because too high a regeneration temperature causes the coating to change, resulting in the disappearance of the dense protective film and the weakening of the anti-poisoning performance of the alloy.

[0137] Lowering the regeneration temperature and comparing the regeneration performance of Comparative Example 5, when the regeneration treatment is carried out at 80 °C, the capacity after regeneration is 1.38 wt.%, which is 83.6% of the original capacity. This is because the lower temperature is not sufficient to provide enough energy for hydrogen molecules to replace the CO molecules with poisoning properties enriched on the alloy surface.

[0138] Lowering the hydrogen pressure used during regeneration and comparing the regeneration performance of Comparative Example 6, the hydrogen pressure used for the regeneration treatment is 1 MPa, and the capacity after regeneration is 1.40 wt.%, which is 84.8% of the original capacity. The lower pressure is not sufficient to enable hydrogen molecules to break through the poisoning layer on the alloy surface to complete the regeneration of the alloy.

[0139] In summary, the hydrogen storage alloy material has good anti-poisoning performance and can effectively block the poisoning of impurity gases such as CO, CO2, and O2 on the hydrogen storage alloy. After 50 anti-poisoning cycles under mixed gas conditions, the capacity retention rate of the hydrogen storage capacity is ≥80.5%; the material can complete regeneration at a relatively low temperature and pressure, and the hydrogen storage capacity after regeneration can be restored to more than 96.5% of the initial capacity.

[0140] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a rare earth TiFe hydrogen storage alloy material with anti-poisoning ability, characterized in that: The following steps are involved: S1: crushing and sieving the rare earth TiFe hydrogen storage alloy to obtain alloy powder with appropriate particle size; S2: pickling the alloy powder, and then washing with water; S3: adding the washed alloy powder into a fluoride solution for fluorination treatment, removing excess fluoride solution after the reaction is completed, and drying; S4: uniformly mixing the fluorinated alloy powder and the polymer and adding an organic solvent until the polymer is completely dissolved to obtain a mixture of the polymer solution and the alloy powder, and completing the preliminary coating of the alloy powder by the polymer; S5: After the initial coating is completed, the mixture is dried to obtain a rare earth TiFe hydrogen storage alloy material with anti-poisoning ability; Wherein, the polymer described in S4 is a polymer material having hydrogen selective permeability.

2. The preparation method according to claim 1, characterized in that: The rare earth TiFe hydrogen storage alloy is one or more of La-TiFe hydrogen storage alloy, Y-TiFe hydrogen storage alloy and Pr-TiFe hydrogen storage alloy.

3. The preparation method according to claim 1, characterized in that: The particle size of the alloy powder in S1 is 100-150 mesh.

4. The preparation method according to claim 1, characterized in that: The specific operation of pickling in S2 is: Prepare a dilute hydrochloric acid solution with a concentration of 1 mol / L to 2 mol / L, add the dilute hydrochloric acid solution to the rare earth TiFe hydrogen storage alloy powder, ensure that the alloy powder is completely immersed in the dilute hydrochloric acid solution, stir and maintain the immersion time for 5 to 10 minutes, and rinse the alloy powder with water until the pH value of the rinse solution is ≥6.

5.

5. The preparation method according to claim 1, characterized in that: The specific operation of fluorination treatment in S3 is: Prepare a 0.05 mol / L to 0.2 mol / L fluoride solution, add the acid-washed rare earth TiFe hydrogen storage alloy powder into the fluoride solution, the alloy powder should be completely covered by the fluoride solution, and continue stirring for 30 minutes to 1 hour; After the reaction is completed, the excess fluoride solution on the surface of the alloy powder is removed by filtration, and then the filtered alloy powder is placed in a vacuum drying oven at 80-100° C. for drying.

6. The preparation method according to claim 5, characterized in that: The fluoride is one or more of nickel fluoride, sodium fluoride and potassium fluoride.

7. The preparation method according to claim 1, characterized in that: The polymer in S4 is one or more of polymethyl methacrylate, epoxy resin, polyamide and polyetheretherketone; The mass ratio of the alloy powder to the polymer is 85-95:5-15.

8. A rare earth TiFe hydrogen storage alloy material with anti-poisoning ability, characterized in that: The alloy material is prepared by the preparation method according to any one of claims 1 to 7, and the surface of the hydrogen storage alloy material has a polymer coating layer with a thickness of 0.5 to 1.5 μm.

9. The hydrogen storage alloy material according to claim 8, characterized in that: After the hydrogen storage alloy material is subjected to 50 anti-poisoning cycles under the conditions of 600ppm CO+300ppm CO2+100ppm O2+a mixed gas of hydrogen and a pressure of 3MPa, the capacity retention rate is ≥80.5%.

10. A method for regenerating the hydrogen storage alloy material according to any one of claims 8 or 9, characterized in that: The specific process is as follows: At a temperature of 100-200°C, use 2-5MPa high-purity hydrogen for regeneration treatment, and the treatment time is 0.5-1h; The purity of the high-purity hydrogen is ≥99.99%, and the hydrogen storage capacity of the hydrogen storage alloy material can be restored to more than 96.5% of the initial capacity after regeneration.

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