A material for improving the resistance of Pd particles to CO poisoning during hydrogen absorption and a method for preparing the same
By combining palladium particles with MOF-74(M) to form a Pd/MOF-74(M) structure, the problem of palladium poisoning of CO gas during hydrogen absorption was solved, achieving high-efficiency hydrogen absorption performance of palladium particles and improving the resistance to CO poisoning and hydrogen absorption rate.
Patent Information
- Application Number
- CN202311790756.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2026-02-03
- Estimated Expiration
- 2043-12-22
AI Technical Summary
In existing technologies, the problem of palladium poisoning CO gas during hydrogen absorption has not been effectively solved, resulting in a decrease in the hydrogen absorption rate. Conventional anti-poisoning methods, such as alloying, lead to element segregation and a reduction in hydrogen absorption capacity.
A Pd/MOF-74(M) composite structure was adopted, and MOF-74(M) was prepared by hydrothermal synthesis or microwave method. The palladium source precursor was loaded on MOF-74(M) to form a Pd/MOF-74(M) composite structure. The MOF-74(M) was used to capture CO gas and prevent it from contacting the palladium particles.
The MOF-74(M) significantly improves the resistance of palladium particles to CO poisoning, enhances the hydrogen absorption rate and capacity, and effectively captures CO gas, ensuring that palladium particles can efficiently absorb hydrogen in hydrogen gas.
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Figure CN117819475B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of hydrogen storage technology, specifically to a material for improving the resistance to CO poisoning during the hydrogen absorption process of Pd particles and its preparation method. Background Technology
[0002] Hydrogen energy, as a highly promising clean energy source, holds the potential to solve the energy crisis. Hydrogen storage materials are among the most important functional materials in hydrogen energy systems and are also key materials in the field of tritium storage. Palladium, as a hydrogen storage material, has become a research focus in new energy and defense research fields due to its advantages such as easy activation, fast hydrogen absorption rate, and resistance to poisoning by impurity gases.
[0003] my country primarily uses fossil fuels for hydrogen production, which inevitably generates some byproduct gases such as CO and CO2. Simultaneously, in tritium-related systems, the decay properties of tritium interact with pipes and valves, leading to the generation of impurity gases such as CO and CH4. These impurity gases severely affect the hydrogen absorption performance of hydrogen storage materials. While palladium possesses excellent resistance to impurity gas poisoning among various hydrogen storage materials, it is still susceptible to its effects. Of the many impurity gases, CO has the greatest impact on palladium's hydrogen absorption performance; when the CO content in H2 reaches 0.1%, the hydrogen absorption rate of palladium decreases significantly. Therefore, modifying palladium to resist CO poisoning and improving its hydrogen absorption rate in atmospheres containing impurity hydrogen has practical application significance.
[0004] When impurity gas particles are adsorbed on the surface of hydrogen storage materials, the adsorption-dissociation active sites originally provided for hydrogen molecules on the material surface are occupied by these impurity particles, thus severely affecting the hydrogen absorption capacity of the storage material. Currently, to address the problem of modifying hydrogen storage materials to resist impurity gas poisoning during hydrogen absorption, alloying methods are generally used, or a Pd film, Pd-Ag film, or Pd-Cu film is coated on the material surface. These methods can improve the resistance to impurity gas poisoning to some extent. For palladium anti-poisoning modification, the focus is mainly on palladium membrane separation applications. Alloyed Pd-Cu and Pd-Au alloys can alleviate CO poisoning to some extent. However, in hydrogen storage applications, palladium alloying easily leads to elemental segregation, reduced hydrogen absorption capacity, and slower hydrogen absorption rate, resulting in relatively little research on related anti-poisoning modification. Summary of the Invention
[0005] The purpose of this invention is to provide a material and its preparation method that improves the resistance of Pd particles to CO poisoning during hydrogen absorption, thereby solving the technical problem that existing technologies do not have a way to improve the resistance of palladium to poisoning.
[0006] This invention discloses a material for improving the resistance to CO poisoning during the hydrogen absorption process of Pd particles. The material is formed by loading palladium particles onto MOF-74(M) to form a Pd / MOF-74(M) composite structure.
[0007] A method for preparing a material that enhances the resistance to CO poisoning during the hydrogen absorption process of Pd particles includes the following steps:
[0008] 1) Preparation of MOF-74(M);
[0009] 2) The solution containing the palladium source precursor was added dropwise to MOF-74(M), and after natural evaporation, it was dried to obtain Pd. 2+ / MOF-74(M);
[0010] 3) To Pd 2+ / MOF-74(M) is purged with hydrogen gas to obtain Pd / MOF-74(M);
[0011] 4) Pd / MOF-74(M) is activated to obtain the product.
[0012] Furthermore, the MOF-74(M) is prepared by hydrothermal synthesis, ball milling or microwave method.
[0013] Furthermore, the CO adsorption capacity of the MOF-74(M) at room temperature is at least 3 mmol / g.
[0014] Furthermore, the MOF-74(M) is: MOF-74(Mg), MOF-74(Ni), MOF-74(Co), or MOF-74(Zn).
[0015] Furthermore, the palladium source is Na2PdCl4, PdCl2, Pd(NO3)2, palladium acetylacetone, or palladium acetate.
[0016] Furthermore, in step 3), hydrogen is used to process Pd 2+ / MOF-74(M) was placed in the tubular furnace and then introduced.
[0017] Furthermore, in step 3), hydrogen gas is introduced at 90°C.
[0018] Furthermore, in step 3), the hydrogen flow rate is 10–40 ml / min, and the hydrogen reaction time is 3–5 h.
[0019] Further, in step 4), activation involves placing Pd / MOF-74(M) into a hydrogen storage reactor, heating it, then hot-draining it for 1 hour, followed by hydrogen reaction and then hot-draining it again.
[0020] Furthermore, the activation temperature in step 4) is 170℃~200℃.
[0021] Furthermore, in step 4), the hydrogen-purging reaction during activation is performed by hot-drying for 5 minutes after each 5-minute hydrogen purging, repeated three times.
[0022] Compared with the prior art, the beneficial effects of the present invention are:
[0023] 1. Existing technologies do not address the resistance of palladium to CO gas poisoning during hydrogen absorption. Conventional anti-poisoning methods, such as alloying, can lead to problems such as palladium alloy element segregation, reduced hydrogen absorption capacity, and reduced hydrogen absorption rate. The inventors of this application propose to combine palladium particles with MOF-74(M) to form a Pd / MOF-74(M) composite structure, which can effectively improve the resistance of palladium to the highly toxic gas CO during hydrogen absorption.
[0024] 2. MOF-74(M) can capture CO. After loading Pd onto MOF-74(M), the impurity gas CO in the hydrogen will be captured by MOF-74(M) during the entire hydrogen absorption process, thereby avoiding the poisoning of palladium caused by contact between CO and palladium particles. Therefore, palladium particles can effectively carry out hydrogen absorption reaction, thereby improving the anti-poisoning performance.
[0025] 3. The Pd / MOF-74(M) composite structure of the present invention has excellent resistance to CO poisoning. Attached Figure Description
[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0027] Figure 1 This is a schematic diagram of the process of the present invention;
[0028] Figure 2 The graph shows the CO adsorption capacity of MOF-74(Ni), MOF-74(Mg), MOF-74(Zn) and MOF-74(Co) at room temperature.
[0029] Figure 3 Microstructure and XRD pattern of Pd / MOF-74(Mg);
[0030] Figure 4 (a) Comparison of hydrogen absorption kinetics between Pd / MOF-74(Mg) and sponge palladium; (b) Hydrogen absorption kinetics of Pd / MOF-74(Mg);
[0031] Figure 5 Microstructure and XRD pattern of Pd / MOF-74(Co);
[0032] Figure 6(a) Comparison of hydrogen absorption kinetics between Pd / MOF-74(Co) and sponge palladium; (b) Hydrogen absorption kinetics of Pd / MOF-74(Co);
[0033] Figure 7 Microstructure and XRD pattern of Pd / MOF-74(Zn);
[0034] Figure 8 (a) Comparison of hydrogen absorption kinetics between Pd / MOF-74(Zn) and sponge palladium; (b) Hydrogen absorption kinetics of Pd / MOF-74(Zn);
[0035] Figure 9 Microstructure and XRD pattern of Pd / MOF-74(Ni);
[0036] Figure 10 Hydrogen adsorption kinetics of Pd / MOF-74(Ni) with different palladium loadings;
[0037] Figure 11 Microstructure and XRD pattern of Pd / HKUST-1;
[0038] Figure 12 Pd / HKUST-1 hydrogen absorption kinetics;
[0039] Figure 13 Microstructure and XRD pattern of Pd / MIL-101(Cr);
[0040] Figure 14 Pd / MIL-101(Cr) hydrogen absorption kinetics. Detailed Implementation
[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0042] Example 1 (MOF-74(Mg)):
[0043] Weigh 3.325 g of Mg(NO3)2·6H2O and 0.775 g of 2,5-dihydroxyterephthalic acid, dissolve them in N,N-dimethylformamide (310 ml), anhydrous ethanol (20 ml), and deionized water (20 ml), and stir magnetically for 0.5 h. Place the mixture in a reaction vessel and react at 120 °C for 24 h. After natural cooling, filter the mixture and wash it three times with deionized water. Then, soak the washed sample in anhydrous ethanol, changing the ethanol every 12 h for two cycles. Finally, filter the sample thoroughly soaked in ethanol and vacuum dry at 150 °C for 12 h to obtain MOF-74(Mg). Dissolve 0.015 g of Na2PdCl4 in 2 ml of anhydrous ethanol and ultrasonically disperse it. Add the solution dropwise to 0.5 g of MOF-74(Mg), allowing it to fully impregnate before allowing it to evaporate naturally. Then, dry the solution in an oven for 2 h. The sample was then placed in a crucible and placed in a tube furnace. The temperature was increased to 90°C at a rate of 5°C / min, followed by the introduction of hydrogen gas at a flow rate of 20 ml / min. After reacting for 5 h, a Pd / MOF-74(Mg) composite structure was obtained. The microstructure and XRD pattern are shown below. Figure 3 The Pd / MOF-74(Mg) structure was not destroyed after loading, and the XRD pattern showed a palladium peak, indicating that palladium was successfully loaded onto the MOFs. ICP-OES testing showed the palladium loading to be 0.98 wt%. After loading the sample into a hydrogen storage tank, it was heated to 180℃ and hot-pumped for 1 hour, followed by hydrogen gas introduction and reaction for 5 minutes, then hot-pumped for 5 minutes, repeated three times, and finally hot-pumped for 1 hour. After natural cooling, it was ready for hydrogen absorption. The reaction procedure is as follows: Figure 1 As shown.
[0044] The hydrogen absorption kinetics curve of Pd / MOF-74(Mg) under the conditions of CO / H2 = 1% and 20℃ is shown below. Figure 4 As shown, compared to the sponge palladium which requires 25 hours to reach hydrogen saturation, this structure can reach saturation in just 45 minutes, increasing the hydrogen absorption rate by 33 times.
[0045] Example 2 (MOF-74(Co)):
[0046] 1.46 g of Co(NO3)2·6H2O and 0.395 g of 2,5-dimethylterephthalic acid were weighed and dissolved in 150 ml of a solution (containing 50 ml each of N,N-dimethylformaldehyde amide, ethanol, and deionized water). The solution was ultrasonically mixed and then loaded into a reaction vessel. Subsequent synthesis conditions were the same as in Example 1, yielding MOF-74(Co). The process of loading palladium onto MOFs was the same as in Example 1, but the mass of Na2PdCl4 was 0.018 g, and the mass of MOF-74(Co) was 0.5 g, finally yielding Pd / MOF-74(Co). The microstructure and XRD pattern are shown below. Figure 5The palladium loading was determined to be 0.97 wt% by ICP-OES.
[0047] The hydrogen absorption kinetics curve of Pd / MOF-74(Co) under the conditions of CO / H2 = 1% and 20℃ is shown below. Figure 6 As shown, this structure requires 2.5 hours to reach hydrogen absorption saturation, increasing the hydrogen absorption rate by 10 times.
[0048] Example 3 (MOF-74(Zn)):
[0049] 1.49 g of Zn(NO3)2·6H2O and 0.395 g of 2,5-dimethylterephthalic acid were weighed and dissolved in 150 ml of a solution (containing 50 ml each of N,N-dimethylformaldehyde amide, ethanol, and deionized water). The solution was ultrasonically mixed and then loaded into a reaction vessel. The subsequent synthesis process was the same as in Example 1, yielding MOF-74(Zn). The process of loading palladium onto MOFs was the same as in Example 1, but the mass of Na2PdCl4 weighed was 0.017 g, and the mass of MOF-74(Zn) weighed was 0.5 g, finally yielding Pd / MOF-74(Zn). The microstructure and XRD pattern are shown below. Figure 7 The palladium loading was determined to be 1.01 wt% by ICP-OES.
[0050] The hydrogen absorption kinetics curve of Pd / MOF-74(Zn) under the conditions of CO / H2 = 1% and 20℃ is shown below. Figure 8 As shown, this structure requires 4 hours to reach hydrogen absorption saturation, and the hydrogen absorption rate is increased by 6 times.
[0051] Example 4 (MOF-74(Ni)):
[0052] 2.99 g of nickel acetate tetrahydrate was weighed, dissolved in 80 ml of deionized water, and sonicated for 5 min. 1.19 g of 2,5-dihydroxyterephthalic acid was weighed, dissolved in 80 ml of tetrahydrofuran, and sonicated for 5 min. These two solutions were mixed in a reaction vessel and stirred until homogeneous. The subsequent synthesis process was the same as in Example 1, yielding MOF-74(Ni). The process of loading palladium onto MOFs was the same as in Example 1. To obtain Pd / MOF-74(Ni) composite structures with palladium loadings of 1 wt%, 5 wt%, and 10 wt%, the amounts of Na2PdCl4 weighed were 0.028 g, 0.145 g, and 0.281 g, respectively, and the amount of MOF-74(Ni) weighed was 0.5 g for each. The final microstructure and XRD pattern of the obtained Pd / MOF-74(Ni) are shown below. Figure 9 The palladium loadings were determined by ICP-OES to be 0.99 wt%, 5.02 wt%, and 9.97 wt%, respectively.
[0053] The hydrogen absorption kinetics curves of Pd / MOF-74(Ni) composite structures with different palladium loadings at CO / H2 = 1% and 20℃ are shown below. Figure 10 As shown in Table 1, the time to reach hydrogen absorption saturation increases with increasing palladium loading. This is because when the palladium loading is low, MOFs can encapsulate more palladium particles, allowing CO to preferentially contact the MOFs and capture CO, thus preventing CO from contacting the palladium particles and improving the palladium particles' resistance to poisoning. Compared to Examples 1-3, MOF-74(Ni) can significantly improve the palladium's resistance to poisoning, indicating that the MOF-74 series contains unsaturated Ni. 2+ Metal sites are better suited for improving palladium's resistance to poisoning.
[0054] Table 1 Comparison of hydrogen absorption saturation time with sponge palladium for different palladium loadings.
[0055]
[0056]
[0057] Example 5 (HKUST-1):
[0058] 3.5 g of Cu(NO3)2·9H2O and 2.15 g of trimellitic acid were weighed and added to a mixed solution (containing 60 ml deionized water, 60 ml anhydrous ethanol, and 60 ml DMF), and stirred until dissolved. The solution was then transferred to a reaction vessel and placed in an oven at 110 °C for 24 h, after which it was removed and allowed to cool naturally to room temperature. After filtration, the unreacted copper nitrate and trimellitic acid were washed with a 1:1 ethanol and aqueous solution, followed by chloroform exchange for three days, with fresh chloroform replaced daily. Finally, HKUST-1 was obtained by vacuum drying at 100 °C. The subsequent palladium loading process was the same as in Example 1, but the amount of Na2PdCl4 weighed was 0.035 g, and the amount of HKUST-1 weighed was 0.5 g, ultimately yielding Pd / HKUST-1. The microstructure and XRD pattern are shown below. Figure 11 The palladium loading was measured to be 1.02 wt% by ICP-OES.
[0059] The hydrogen absorption kinetics curve of the Pd / HKUST-1 composite structure under the conditions of CO / H2 = 1% and 20℃ is as follows: Figure 12 As shown, the structure requires 22 hours to reach hydrogen absorption saturation and has little effect on improving the anti-poisoning ability of palladium.
[0060] Example 6 (MIL-101(Cr)):
[0061] 4.2 g of (Cr(NO3)3·9H2O), 1.64 g of terephthalic acid, and 3.2 ml of glacial acetic acid were weighed and added to deionized water. After thorough mixing, the mixture was transferred to a reaction vessel and reacted at 200 °C for 8 h. A blue powder was obtained by filtration, and then heated in ethanol at 60 °C for 3 h. This process was repeated twice. After filtration, the powder was dried at 100 °C for 2 h to obtain MIL-101(Cr). The subsequent palladium loading process was the same as in Example 1, but the amount of Na2PdCl4 weighed was 0.039 g, and the amount of MIL-101(Cr) weighed was 0.5 g, finally yielding Pd / MIL-101(Cr). The microstructure and XRD pattern are shown below. Figure 13 The palladium loading was measured to be 0.99 wt% by ICP-OES.
[0062] The hydrogen absorption kinetics curve of the Pd / MIL-101(Cr) composite structure under the conditions of CO / H2 = 1% and 20℃ is as follows: Figure 14 As shown, this structure requires 20 hours to reach hydrogen absorption saturation and has little effect on improving the anti-poisoning ability of palladium.
[0063] Differences between Examples 1-4: A series of MOF-74 with different unsaturated metal sites were prepared. Different metal sites have different effects on improving the anti-poisoning performance of palladium. Specifically, MOF-74(Ni) > MOF-74(Mg) > MOF-74(Co) > MOF-74(Zn). The reason is that different metal sites have different binding energies with CO. Among the many unsaturated metal sites, CO has a stronger interaction with Ni2+, so MOF-74(Ni) has a stronger ability to adsorb CO.
[0064] In Example 4, MOF-74(Ni) with different palladium loadings were prepared. The anti-poisoning performance improved with decreasing palladium loading. This is because a lower palladium loading allows the MOFs to encapsulate more palladium particles, enabling CO to preferentially contact the MOFs and capture CO, thus preventing CO from contacting the palladium particles and improving their anti-poisoning ability. Considering the total hydrogen absorption, composite structure integrity, and improved anti-poisoning ability, it is advisable to control the palladium loading to below 10%.
[0065] Examples 5 and 6 are common examples with unsaturated Cu 2+ HKUST-1 with metal sites and Cr 3+ While MIL-101(Cr) is used at the metal site, its effect on improving the CO poisoning resistance of palladium particles is not significant compared to the MOF-74 series. These two examples highlight the importance of the MOF-74 series in enhancing anti-poisoning performance in this invention.
[0066] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments based on the inspiration of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be determined by the claims, and the specification can be used to interpret the claims.
Claims
1. A material for improving the resistance to CO poisoning during the hydrogen absorption process of Pd particles, characterized in that: The material is a Pd / MOF-74(M) composite structure in which palladium particles are loaded onto MOF-74(M); Its preparation method includes the following steps: 1) Preparation of MOF-74(M); 2) The solution containing the palladium source precursor was added dropwise to MOF-74(M), and after natural evaporation, it was dried to obtain Pd. 2+ / MOF-74(M); 3) To Pd 2+ / MOF-74(M) is purged with hydrogen gas to obtain Pd / MOF-74(M); 4) Pd / MOF-74(M) is obtained by activation.
2. A method for preparing a material that enhances the resistance to CO poisoning during the hydrogen absorption process of Pd particles, characterized in that: Includes the following steps: 1) Preparation of MOF-74(M); 2) The solution containing the palladium source precursor was added dropwise to MOF-74(M), and after natural evaporation, it was dried to obtain Pd. 2+ / MOF-74(M); 3) To Pd 2+ / MOF-74(M) is purged with hydrogen gas to obtain Pd / MOF-74(M); 4) Pd / MOF-74(M) is obtained by activation.
3. The method for preparing a material to enhance the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 2, characterized in that: The MOF-74(M) was prepared by hydrothermal synthesis, ball milling or microwave method.
4. The method for preparing a material to enhance the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 2, characterized in that: The MOF-74(M) is: MOF-74(Ni), MOF-74(Mg), MOF-74(Co), or MOF-74(Zn).
5. The method for preparing a material to enhance the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 2, characterized in that: The palladium source is Na2PdCl4, PdCl2, Pd(NO3)2, palladium acetylacetone, or palladium acetate.
6. The method for preparing a material to enhance the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 2, characterized in that: In step 3), hydrogen is used to process Pd 2+ / MOF-74(M) was placed in the tubular furnace and then introduced.
7. The preparation method of a material for improving the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 2, characterized in that: In step 3), the hydrogen flow rate is 10~40 ml / min, and the hydrogen reaction time is 3~5 h.
8. The method for preparing a material to enhance the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 2, characterized in that: In step 4), activation involves placing Pd / MOF-74(M) into a hydrogen storage reactor, heating it, and then hot-evacuating it for 1 hour. Subsequently, hydrogen is introduced to react, followed by hot-evacuation.
9. The method for preparing a material to enhance the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 8, characterized in that: In step 4), the activation process involves hydrogen purging followed by thermal extraction for 5 minutes after each 5-minute hydrogen purging, repeated three times.
10. The method for preparing a material to enhance the resistance to CO poisoning during the hydrogen absorption process of Pd particles according to claim 2, characterized in that: The activation temperature in step 4) is 170℃~200℃.