Pt-co-mo-nc hollow structure catalyst for ammonia-borane hydrolysis to produce hydrogen and preparation method thereof
By preparing a Pt-CoMo-NC hollow structure catalyst, the synergistic effect of Pt and Mo was utilized to solve the problems of high cost of precious metals and easy agglomeration of non-precious metals, achieving efficient hydrogen production by hydrolysis of ammonia borane with significantly improved catalytic activity, making it suitable for hydrogen production and storage.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HENAN UNIV OF SCI & TECH
- Filing Date
- 2024-02-07
- Publication Date
- 2026-07-07
AI Technical Summary
Existing precious metal catalysts such as Pt are expensive and rare, while non-precious metal catalysts are prone to agglomeration, resulting in low efficiency of hydrogen production from the hydrolysis of ammonia borane and making it difficult to apply them widely. The performance of existing non-precious metal catalysts is inferior to that of precious metal catalysts, and their catalytic activity is insufficient.
A Pt-CoMo-NC hollow structure catalyst was prepared by high-temperature calcination. By utilizing the synergistic effect of Pt and Mo, the metal nanoparticles in the catalyst are distributed on the carbon matrix to form a hollow structure, thereby improving the utilization rate of precious metals and catalytic activity.
The method achieves highly efficient catalytic hydrolysis of ammonia borane to produce hydrogen, with a conversion frequency as high as 3637 molH2·min-1·molPt-1. The catalytic activity is significantly improved, the utilization rate of precious metals is increased, the operation is simple, and the raw materials are readily available.
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Figure CN118022807B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation and its application in hydrogen production energy, specifically relating to a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane and its preparation method. Background Technology
[0002] Currently, the consumption of fossil fuel-based energy has caused various environmental problems. At the same time, increasing energy demand necessitates the development of renewable and sustainable energy sources. Hydrogen energy is considered an attractive environmentally friendly energy source due to its high energy density and excellent renewability. However, the further application of hydrogen remains a significant challenge; hydrogen storage, transportation, and production are key issues for the hydrogen economy and hydrogen technology. Chemical hydrogen storage is an effective method, but the controlled release of hydrogen from chemical storage materials still faces considerable challenges.
[0003] The preparation of clean and renewable hydrogen through the hydrolysis of ammonia borane is one of the effective ways to solve the energy problem. Ammonia borane, with its high hydrogen content and low molecular weight, is an excellent hydrogen storage material. It exhibits excellent chemical stability under mild conditions, and its non-toxicity and ease of transportation promote its application in hydrogen storage and dehydrogenation. Ammonia borane can hydrolyze to produce hydrogen at room temperature, and under the action of a catalyst, it can rapidly and efficiently release hydrogen. Noble metal catalysts have excellent catalytic activity for the hydrolysis of ammonia borane, but their high cost and global scarcity greatly limit their widespread application. While non-noble metals such as Co, Ni, Cu, and Fe are inexpensive and abundant, the performance of currently reported non-noble metal catalysts still lags behind that of noble metal catalysts, and non-noble metal nanocatalysts are prone to aggregation. Therefore, developing novel, efficient, and stable two-component or multi-component catalysts to efficiently catalyze the hydrolysis of ammonia borane to produce hydrogen through the synergistic effect between metals is of significant scientific importance.
[0004] In existing technologies, platinum-based nanomaterials are widely used as the most effective catalysts in hydrogen storage and other chemical conversion reactions. However, the rarity of Pt and its ever-increasing demand result in very high costs, which is the biggest challenge to its widespread application. Therefore, developing Pt-based polymetallic nanomaterials (alloys, core-shell, intermetallic materials) to partially replace Pt and obtain the same or even better catalytic activity is of great significance to the development of the hydrogen production and storage industry. Summary of the Invention
[0005] To address the aforementioned issues, this invention proposes a Pt-CoMo-NC hollow structure catalyst for hydrogen production from ammonia borane hydrolysis and its preparation method, aiming to improve the utilization rate of precious metals and enhance the catalytic activity of the catalyst to meet the needs of practical production applications.
[0006] This invention is achieved through the following technical solution:
[0007] A method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane is disclosed, which uses ZIF-67 modified with both Pt and Mo as a precursor and prepares the catalyst by high-temperature carbonization in an inert atmosphere, thereby obtaining a catalyst with synergistic effects of noble metals and non-noble metals.
[0008] Furthermore, a method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane includes the following specific preparation steps:
[0009] Step 1: Prepare ZIF-67 powder;
[0010] Step 2: Dissolve the Mo source and chloroplatinic acid completely in the solvent, add ZIF-67 powder to the solution under stirring at 20-35℃, and continue stirring at this temperature for 10-60 min.
[0011] Step 3: Stir continuously at 60-80℃ until the solvent is completely evaporated to obtain MoPt / ZIF-67;
[0012] Step 4: Carbonize MoPt / ZIF67 in an inert gas at a temperature of 500-950℃ to obtain the Pt-CoMo-NC catalyst.
[0013] Furthermore, in step one, the specific method for preparing ZIF-67 powder is as follows:
[0014] S1. Dissolve cobalt nitrate in methanol to obtain solution A, and dissolve 2-methylimidazole in methanol to obtain solution B;
[0015] S2. Under stirring conditions, solution A is quickly added to solution B, and stirring is continued for 10-72 h at a temperature of 25-30℃. After centrifugation, washing, and vacuum drying, ZIF-67 powder is obtained.
[0016] Furthermore, in S1, the ratio of the molar amount of cobalt nitrate (mol) to the volume of methanol (L) is 1:15-20.
[0017] The ratio of the molar amount (mol) of 2-methylimidazole to the volume (L) of methanol is 1:1-2.
[0018] Furthermore, in S2, the molar ratio of cobalt nitrate to 2-methylimidazole is 1:4-5.
[0019] Furthermore, in step two, the Mo source is any one of ammonium molybdate, sodium molybdate, or molybdenum acetylacetonate.
[0020] Furthermore, in step two, the solvent is methanol or ethanol.
[0021] Furthermore, in step two, the mass ratio of Mo atoms to ZIF-67 is 1:5-50, the mass ratio of chloroplatinic acid to ZIF-67 is 1:200-2000, and the ratio of solvent volume (mL) to ZIF-67 mass (mg) is 0.3-0.5:1.
[0022] Furthermore, in step four, the inert gas is any one of nitrogen, argon, and helium, and the heating rate for carbonization in the inert gas is 0.5-6℃ / min.
[0023] A Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane was prepared by the above-mentioned preparation method. In this catalyst, metal nanoparticles are distributed on a carbon matrix and the catalyst has a hollow structure.
[0024] The beneficial effects of this invention are as follows:
[0025] (1) The present invention uses high-temperature calcination to prepare Pt-CoMo-NC hollow structure catalyst. The method is simple and the raw materials are readily available. The synergistic effect of noble metals and non-noble metals in the catalyst makes the catalyst exhibit good catalytic performance and improves the utilization rate of noble metals.
[0026] (2) At 298 K, the conversion frequency (TOF) of the prepared Pt-CoMo-NC hollow structure catalyst for the complete hydrolysis and dehydrogenation of ammonia borane reached as high as 3637 mol. H2 ·min -1 ·mol Pt -1 This indicates that the catalyst has good catalytic activity. The excellent activity of the Pt-CoMo-NC hollow structure catalyst is attributed to the synergistic effect between noble and non-noble metals and electronic effects. Attached Figure Description
[0027] Figure 1 These are scanning electron microscope (SEM) images (a) and (b), transmission electron microscope (TEM) images (c) and high-resolution transmission electron microscope (HRTEM) images (d) of the noble metal and non-noble metal catalysts prepared in Example 1 of this invention.
[0028] Figure 2 These are test graphs showing the catalytic hydrogen release performance of the catalysts prepared in Examples 1-5 of this invention under room temperature conditions for hydrolysis of ammonia borane;
[0029] Figure 3 These are test graphs showing the catalytic hydrogen release performance of the catalysts prepared in Examples 1 and 6-9 of this invention under room temperature conditions for hydrolysis of ammonia borane. Detailed Implementation
[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.
[0031] Example 1:
[0032] A method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane specifically includes the following steps:
[0033] 1) Preparation of ZIF-67: 12 mmol of cobalt nitrate was dissolved in 120 mL of methanol to obtain a clear solution A, and 48 mmol of 2-methylimidazole was dissolved in 40 mL of methanol to obtain a clear solution B. Solution A was rapidly added to solution B under stirring, and stirring was continued at 25 °C for 24 hours. After centrifugation, the solution was washed three times with methanol and dried in a vacuum oven at 100 °C for 12 hours to obtain ZIF-67.
[0034] 2) Preparation of MoPt / ZIF-67: 0.1 mmol of molybdenum acetylacetonate and 3 mL of chloroplatinic acid aqueous solution with a concentration of 0.0001 g / mL were completely dissolved in 30 mL of methanol. 100 mg of the prepared ZIF-67 was added to the above solution under stirring at 25 °C. After stirring for 0.5 h, stirring was continued at 65 °C until the solvent was completely evaporated to obtain MoPt / ZIF-67.
[0035] 3) Preparation of Pt-CoMo-NC hollow structure catalyst: MoPt / ZIF-67 was carbonized at 600℃ for 2 h under nitrogen atmosphere to obtain Pt-CoMo-NC catalyst.
[0036] Example 2:
[0037] The amount of molybdenum acetylacetone described in step 2) of Example 1 was changed to 0 mmol, and the other steps were the same as in Example 1, to obtain the Pt-Co-NC catalyst.
[0038] Example 3:
[0039] The amount of molybdenum acetylacetonate in step 2) of Example 1 was changed to 0.05 mmol, and the other steps were the same as in Example 1, to obtain the Pt-CoMo-NC hollow structure catalyst.
[0040] Example 4:
[0041] The amount of molybdenum acetylacetonate described in step 2) of Example 1 was changed to 0.15 mmol, and the other steps were the same as in Example 1, to obtain the Pt-CoMo-NC hollow structure catalyst.
[0042] Example 5:
[0043] The amount of molybdenum acetylacetonate described in step 2) of Example 1 was changed to 0.2 mmol, and the other steps were the same as in Example 1, to obtain the Pt-CoMo-NC hollow structure catalyst.
[0044] Example 6:
[0045] The amount of 3 mL of chloroplatinic acid aqueous solution mentioned in step 2) of Example 1 was changed to 0 mL, and the other steps were the same as in Example 1, to obtain the CoMo-NC catalyst.
[0046] Example 7:
[0047] The amount of 3 mL of chloroplatinic acid aqueous solution mentioned in step 2) of Example 1 was changed to 5 mL, and the other steps were the same as in Example 1, to obtain the Pt-CoMo-NC hollow structure catalyst.
[0048] Example 8:
[0049] The amount of 3 mL of chloroplatinic acid aqueous solution mentioned in step 2) of Example 1 was changed to 7.5 mL, and the other steps were the same as in Example 1, to obtain the Pt-CoMo-NC hollow structure catalyst.
[0050] Example 9:
[0051] The amount of 3 mL of chloroplatinic acid aqueous solution mentioned in step 2) of Example 1 was changed to 10 mL, and the other steps were the same as in Example 1, to obtain the Pt-CoMo-NC hollow structure catalyst.
[0052] The performance of the prepared catalyst was evaluated by water displacement under constant temperature magnetic stirring at 25 °C. 10 mg of the catalyst, dispersed in 5 mL of deionized water, was added to a round-bottom flask, followed by 10 mL of deionized water containing 1 mmol of ammonia borane and 0.667 mmol of sodium hydroxide. The catalytic performance of this catalyst in the hydrolysis of ammonia borane is shown in the figure. Figure 2 , 3 .
[0053] SEM and TEM images of the Pt-CoMo-NC catalyst prepared in this embodiment are shown below. Figure 1 As shown, the catalyst retains the rhombic dodecahedral structure of ZIF-67, only the surface becomes rougher, and a hollow structure is visible. Furthermore, this catalyst exhibits good catalytic activity for the hydrolysis of ammonia borane to produce hydrogen; at the optimal ratio, ammonia borane is completely released into hydrogen within 3 minutes. Its excellent activity is attributed to the synergistic effect between noble and non-noble metals, the ultrafine Pt metal nanoparticles, and the electronic regulation of Co by Mo.
[0054] In summary, the method for preparing the catalyst of the present invention is simple to operate, requires a small amount of precious metal, and the obtained catalyst has the characteristics of small particle size, multiple catalytic active sites, and high catalytic activity, making it a catalyst with great development potential.
[0055] It should be noted that although the present invention has been described through the above embodiments, the present invention may have many other embodiments. Without departing from the spirit and scope of the present invention, those skilled in the art can obviously make various corresponding changes and modifications to the present invention, but all such changes and modifications should fall within the scope of protection of the appended claims and their equivalents.
Claims
1. A method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane, characterized in that: A catalyst with synergistic effects of noble metals and non-noble metals was prepared by high-temperature carbonization in an inert atmosphere using Pt and Mo-modified ZIF-67 as a precursor. The specific preparation steps are as follows: Step 1: Prepare ZIF-67 powder; Step 2: Dissolve the Mo source and chloroplatinic acid completely in a solvent to obtain a solution. Add ZIF-67 powder to the solution while stirring at 20-35℃, and continue stirring at this temperature for 10-60 minutes. Step 3: Stir continuously at 60-80℃ until the solvent is completely evaporated to obtain MoPt / ZIF-67; Step 4: Carbonize MoPt / ZIF67 in an inert gas at a temperature of 500-950℃ to obtain a Pt-CoMo-NC catalyst; the metal nanoparticles in the catalyst are distributed on the carbon matrix and the catalyst has a hollow structure.
2. The method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane according to claim 1, characterized in that: In step one, the specific method for preparing ZIF-67 powder is as follows: S1. Dissolve cobalt nitrate in methanol to obtain solution A, and dissolve 2-methylimidazole in methanol to obtain solution B; S2. Under stirring conditions, solution A is quickly added to solution B, and stirring is continued for 10-72 hours at a temperature of 25-30℃. After centrifugation, washing, and vacuum drying, ZIF-67 powder is obtained.
3. The method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane according to claim 2, characterized in that: In S1, during the preparation of solution A, the ratio of the molar amount of cobalt nitrate (mol) to the volume of methanol (L) is 1:15-20. In the preparation of solution B, the ratio of the molar amount of 2-methylimidazole (mol) to the volume of methanol (L) is 1:1-2.
4. The method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane according to claim 2, characterized in that: In S2, the molar ratio of cobalt nitrate to 2-methylimidazole is 1:4-5.
5. The method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane according to claim 1, characterized in that: In step two, the Mo source is any one of ammonium molybdate, sodium molybdate, or molybdenum acetylacetonate.
6. The method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane according to claim 1, characterized in that: In step two, the solvent is methanol or ethanol.
7. The method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane according to claim 1, characterized in that: In step two, the mass ratio of Mo atoms to ZIF-67 is 1:5-50, the mass ratio of chloroplatinic acid to ZIF-67 is 1:200-2000, and the ratio of solvent volume (mL) to ZIF-67 mass (mg) is 0.3-0.5:
1.
8. The method for preparing a Pt-CoMo-NC hollow structure catalyst for hydrogen production by hydrolysis of ammonia borane according to claim 1, characterized in that: In step four, the inert gas is any one of nitrogen, argon, and helium, and the heating rate for carbonization in the inert gas is 0.5-6℃ / min.