A CoMoP ternary catalyst and its preparation method and application

Abstract

The invention provides a CoMoP ternary Catalyst and a preparation method and application thereof, belonging to the field of catalyst preparation and hydrogen production energy application. The catalyst is prepared by the following steps: adding cobalt nitrate to methanol to dissolve to obtain a transparent solution A; adding 2-methylimidazole to the methanol solution to dissolve to obtain a transparent solution B; rapidly adding solution A to solution B under stirring, continuing stirring at a temperature of 20-30°C for 12-48 hours, centrifuging, washing, and drying to obtain ZIF-67; completely dissolving a Mo source in a solvent, adding ZIF-67 under stirring at 20-30°C, mixing uniformly, heating to 65-80°C, and continuously stirring until the solvent is completely evaporated to obtain Mo / ZIF-67; and controlling the mass ratio of Mo / ZIF-67 to sodium hypophosphite, and phosphating under a nitrogen atmosphere to obtain the CoMoP ternary Catalyst. The catalyst has good performance in catalyzing ammonia borane hydrolysis hydrogen production reaction and has good application prospects.

Description

Technical Field

[0001] The present invention belongs to the field of catalyst preparation and hydrogen production energy application, and specifically relates to a CoMoP ternary catalyst and a preparation method and application thereof. Background Art

[0002] At present, the increasingly serious environmental problems caused by the large-scale consumption of fossil fuels such as coal, oil and natural gas have promoted the development of renewable and high-efficiency energy materials. Renewable energy such as solar energy, wind energy, bioenergy and hydrogen energy have attracted attention. Among them, hydrogen energy is regarded as a potential energy carrier due to its abundant sources and green and environmentally friendly characteristics. Compared with other hydrocarbon fuels, hydrogen contains higher chemical energy per unit mass, and the only product of hydrogen combustion, water, can continue to produce hydrogen through electrolysis, photolysis and other means and be recycled repeatedly. The storage of hydrogen energy is a key issue restricting the development of the hydrogen energy economy. Designing a safe and efficient hydrogen storage and release system is one of the urgent problems to be solved in order to achieve large-scale utilization of hydrogen energy.

[0003] Producing clean, renewable hydrogen by hydrolyzing ammonia borane is an effective approach to addressing energy challenges. Ammonia borane is a promising hydrogen storage material with a hydrogen content of up to 19.6%, stable properties at room temperature, and non-toxic. Ammonia borane can hydrolyze to hydrogen at room temperature, releasing hydrogen rapidly and efficiently in the presence of a catalyst. Catalysts prepared with noble metals such as Ru, Rh, Pt, and Pd as active components exhibit excellent catalytic performance in the ammonia borane hydrolysis reaction. However, the high price and limited reserves of noble metals hinder their large-scale application. Among non-noble metals, Co, Ni, and Cu exhibit high catalytic activity in the hydrolysis of ammonia borane to produce hydrogen, but their catalytic activity still lags behind that of noble metal catalysts. The preparation of dual-component or multi-component catalysts and the exploitation of intermetallic synergistic effects can effectively enhance catalytic performance.

[0004] Compared with single-component or two-component non-precious catalysts, three-component and above nanocatalysts show higher catalytic activity. Liang et al. [Journal of Alloys and Compounds 2018 (741): 501-508] used solvent evaporation to fix highly dispersed Cu-Ni-Co nanoparticles on the pores of MIL-101. Due to the synergistic effect between Cu, Ni and Co, the catalyst was catalyzed by the hydrolysis of ammonia borane and the reaction time was 72.1 min. -1The TOF value of 1.5 wt% was 1.5 wt% . The CoNiP / GO catalyst prepared by Chen et al. [Chemical Engineering Journal 2022 (428): 131-219] exhibited excellent catalytic activity and cyclic stability in the hydrolysis of ammonia borane. Non-precious metal catalysts have broad commercial application prospects in the field of hydrogen storage materials due to their low price and excellent catalytic activity. However, based on current research, the research and application of three-component or higher non-precious metal nanocatalysts are relatively limited. Summary of the Invention

[0005] In view of the above problems, an object of the present invention is to provide a method for preparing a CoMoP ternary catalyst.

[0006] Another object of the present invention is to provide a CoMoP ternary catalyst prepared by the above preparation method.

[0007] Another object of the present invention is to provide the use of the above-mentioned CoMoP ternary catalyst in catalyzing the hydrolysis of ammonia borane.

[0008] In order to achieve the above object, the specific scheme adopted by the present invention is:

[0009] In a first aspect, a method for preparing a CoMoP ternary catalyst comprises the following preparation steps:

[0010] Step 1: adding cobalt nitrate into methanol to dissolve to obtain a transparent solution A;

[0011] Step 2: Add 2-methylimidazole to methanol and dissolve it to obtain a transparent solution B;

[0012] Step 3: Rapidly add solution A to solution B under stirring, continue stirring at a temperature of 20-30°C for 12-48 hours, centrifuge and wash, and then dry in a vacuum oven at 50-100°C to obtain ZIF-67;

[0013] Step 4: Dissolve the Mo source completely in the solvent, and add the prepared ZIF-67 to the above solution under stirring at 20-30°C;

[0014] Step 5: After mixing evenly, continue stirring at 65-80°C until the solvent is completely evaporated to obtain Mo / ZIF-67;

[0015] Step 6: Control the mass ratio of Mo / ZIF-67 to sodium hypophosphite to be 1:1-1:20, and perform phosphating at a temperature of 300-600° C. under a nitrogen atmosphere to obtain a CoMoP ternary catalyst.

[0016] Furthermore, in step 1, the ratio of cobalt nitrate (molar amount mol) to methanol (volume L) is 1:10-20.

[0017] Furthermore, in step 2, the ratio of 2-methylimidazole (molar amount mol) to methanol (volume L) is 1:0.8-2.

[0018] Furthermore, in step 3, the molar ratio of cobalt nitrate in solution A to 2-methylimidazole in solution B is 1:4-5.

[0019] Furthermore, in step 4, the Mo source is any one of molybdenum chloride, molybdenum nitrate or molybdenum acetylacetonate.

[0020] Furthermore, in step 4, the solvent is methanol or ethanol.

[0021] Furthermore, in step 4, the mass ratio of Mo atoms to ZIF-67 is 1:1-100, and the ratio of solvent (volume mL) to ZIF-67 (mass mg) is 0.3-0.5:1.

[0022] Furthermore, in step five, the solvent evaporation temperature is 65-80°C.

[0023] Furthermore, in step six, the mass ratio of Mo / ZIF-67 to sodium hypophosphite is 1:1-1:20.

[0024] Furthermore, in step six, the heating rate of phosphating in a nitrogen atmosphere is 1-5°C / min.

[0025] In a second aspect, a CoMoP ternary catalyst is prepared using the above preparation method.

[0026] Thirdly, the application of the above-mentioned CoMoP ternary catalyst in catalyzing the hydrolysis of ammonia borane to produce hydrogen.

[0027] The beneficial effects of the present invention are as follows: the catalyst preparation method of the present invention is simple, inexpensive and easily available, and the synergistic effect of the three components CoMoP in the catalyst enables the catalyst to exhibit better catalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a SEM image of the catalyst prepared in Example 1 of the present invention;

[0029] Figure 2 is a TEM image of the catalyst prepared in Example 1 of the present invention;

[0030] Figure 3 is a TEM image of the catalyst prepared in Example 1 of the present invention;

[0031] Figure 4is a TEM image of the catalyst prepared in Example 1 of the present invention;

[0032] Figure 5 This is a test chart showing the performance of the catalysts prepared in Example 1 of the present invention and Comparative Examples 2-3 in catalyzing the hydrolysis and hydrogenation of ammonia borane at room temperature;

[0033] Figure 6 This is a test chart of the performance of the catalysts prepared in Example 1 of the present invention and Comparative Example 4 in catalyzing the hydrolysis and hydrogenation of ammonia borane at room temperature. DETAILED DESCRIPTION

[0034] A method for preparing a CoMoP ternary catalyst comprises the following steps:

[0035] Step 1: adding cobalt nitrate into methanol to dissolve to obtain a transparent solution A;

[0036] Step 2: Add 2-methylimidazole to methanol and dissolve it to obtain a transparent solution B;

[0037] Step 3: Rapidly add solution A to solution B under stirring, continue stirring at a temperature of 20-30°C for 12-48 hours, centrifuge and wash, and then dry in a vacuum oven at 50-100°C to obtain ZIF-67;

[0038] Step 4: Dissolve the Mo source completely in the solvent, and add the prepared ZIF-67 to the above solution under stirring at 20-30°C;

[0039] Step 5: After mixing evenly, continue stirring at 65-80°C until the solvent is completely evaporated to obtain Mo / ZIF-67;

[0040] Step 6: Control the mass ratio of Mo / ZIF-67 to sodium hypophosphite to be 1:1-1:20, and perform phosphating at a temperature of 300-600° C. under a nitrogen atmosphere to obtain a CoMoP ternary catalyst.

[0041] Furthermore, in step 1, the ratio of cobalt nitrate (molar amount mol) to methanol (volume L) is 1:10-20.

[0042] Furthermore, in step 2, the ratio of 2-methylimidazole (molar amount mol) to methanol (volume L) is 1:0.8-2.

[0043] Furthermore, in step 3, the molar ratio of cobalt nitrate in solution A to 2-methylimidazole in solution B is 1:4-5.

[0044] Furthermore, in step 4, the Mo source is any one of molybdenum chloride, molybdenum nitrate or molybdenum acetylacetonate.

[0045] Furthermore, in step 4, the solvent is methanol or ethanol.

[0046] Furthermore, in step 4, the mass ratio of Mo atoms to ZIF-67 is 1:1-100, and the ratio of solvent (volume mL) to ZIF-67 (mass mg) is 0.3-0.5:1.

[0047] Furthermore, in step five, the solvent evaporation temperature is 65-80°C.

[0048] Furthermore, in step six, the mass ratio of Mo / ZIF-67 to sodium hypophosphite is 1:1-1:20.

[0049] Furthermore, in step six, the heating rate of phosphating in a nitrogen atmosphere is 1-5°C / min.

[0050] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0051] Example 1

[0052] 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 quickly added to solution B with 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. 0.0326 g of molybdenum acetylacetonate was dissolved in 30 mL of methanol to obtain solution C. 100 mg of ZIF-67 was quickly added to solution C with stirring, and stirring was continued at 25°C for 0.5 hour until thoroughly mixed and dissolved. The temperature was then raised to 65°C and stirring was continued until the solvent was completely evaporated, resulting in Mo / ZIF-67. 10 mg of Mo / ZIF-67 and 100 mg of sodium hypophosphite were weighed and placed in a tubular furnace under a nitrogen atmosphere (sodium hypophosphite was at the upstream) and heated to 300°C at a heating rate of 2°C / min and kept at that temperature for 6 hours. Then, the temperature was increased to 600°C at a heating rate of 2°C / min and kept at that temperature for 1 hour. After cooling to room temperature, the mixture was taken out to prepare the CoMoP ternary catalyst.

[0053] The SEM image of the CoMoP-NC catalyst prepared in this example is shown in FIG. Figure 1 As shown, the catalyst still maintains the rhombic dodecahedron structure of ZIF-67, but the surface changes from smooth to wrinkled. Figure 2-4 This is the TEM image of the CoMoP-NC catalyst prepared in this example. It can be seen that the catalyst forms a hollow structure.

[0054] The performance of the prepared catalyst was evaluated by the water displacement method under constant temperature and magnetic stirring at 25°C. 10 mg of the above catalyst dispersed in 5 mL of deionized water was added to a round-bottom flask, followed by a mixture of 1 mmol of ammonia borane and 0.667 mmol of sodium hydroxide in 10 mL of deionized water. The performance of the catalyst in catalyzing the hydrolysis of ammonia borane is shown in Figure 1. Figure 5 , ammonia borane completely releases hydrogen within 5 minutes.

[0055] Comparative Example 2

[0056] 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 quickly added to solution B with stirring, and stirring was continued at 25°C for 24 hours. After centrifugation, the mixture was washed three times with methanol and dried in a vacuum oven at 100°C for 12 hours to obtain ZIF-67. 0.0326 g of molybdenum acetylacetonate was dissolved in 30 mL of methanol to obtain solution C. 100 mg of ZIF-67 was quickly added to solution C with stirring, and stirring was continued at 25°C for 0.5 hour until thoroughly mixed and dissolved. The temperature was then raised to 65°C and stirred continuously until the solvent was completely evaporated, yielding Mo / ZIF-67. 100 mg of Mo / ZIF-67 was placed in a tube furnace under a nitrogen atmosphere and heated at a rate of 2°C / min to 600°C. The mixture was then held for 2 hours, cooled to room temperature, and removed to obtain CoMo-NC.

[0057] The performance of the prepared catalyst was evaluated by the water displacement method under constant temperature and magnetic stirring at 25°C. 10 mg of the above catalyst dispersed in 5 mL of deionized water was added to a round-bottom flask, followed by a mixture of 1 mmol of ammonia borane and 0.667 mmol of sodium hydroxide in 10 mL of deionized water. The performance of the catalyst in catalyzing the hydrolysis of ammonia borane is shown in Figure 1. Figure 5 , ammonia borane completely released hydrogen within 18 minutes.

[0058] Comparative Example 3

[0059] Dissolve 12 mmol of cobalt nitrate in 120 mL of methanol to obtain a clear solution A, and dissolve 48 mmol of 2-methylimidazole in 40 mL of methanol to obtain a clear solution B. Solution A was quickly added to solution B with 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. A 100 mg portion of ZIF-67 was placed in a tube furnace under a nitrogen atmosphere and heated at a rate of 2°C / min to 600°C. The temperature was then maintained for 2 hours, cooled to room temperature, and removed to obtain Co-NC.

[0060] The performance of the prepared catalyst was evaluated by the water displacement method under constant temperature and magnetic stirring at 25°C. 10 mg of the above catalyst dispersed in 5 mL of deionized water was added to a round-bottom flask, followed by a mixture of 1 mmol of ammonia borane and 0.667 mmol of sodium hydroxide in 10 mL of deionized water. The performance of the catalyst in catalyzing the hydrolysis of ammonia borane is shown in Figure 1. Figure 5 , only 45 mL of H2 can be released in 45 minutes.

[0061] Comparative Example 4

[0062] 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 quickly added to solution B with stirring, and stirring was continued at 25°C for 24 hours. After centrifugation, the mixture was washed three times with methanol and dried in a vacuum oven at 100°C for 12 hours to obtain ZIF-67. 0.0326 g of molybdenum acetylacetonate was dissolved in 30 mL of methanol to obtain solution C. 100 mg of ZIF-67 was quickly added to solution C with stirring, and stirring was continued at 25°C for 0.5 hour until thoroughly mixed and dissolved. The mixture was then heated to 65°C and stirred continuously until the solvent was completely evaporated, yielding Mo / ZIF-67. 100 mg of Mo / ZIF-67 was placed in a tube furnace under a nitrogen atmosphere and heated at a rate of 2°C / min to 600°C. The mixture was then held for 2 hours, cooled to room temperature, and removed to obtain CoMo-NC. 10 mg of CoMo-NC and 100 mg of sodium hypophosphite were weighed and placed in a tubular furnace under a nitrogen atmosphere (sodium hypophosphite was at the upstream) and heated to 300°C at a rate of 2°C / min. The mixture was kept at this temperature for 1 hour, cooled to room temperature, and then taken out to obtain a CoMoP ternary catalyst, which was recorded as CoMoP-NC (step-by-step).

[0063] The performance of the prepared catalyst was evaluated by the water displacement method under constant temperature and magnetic stirring at 25°C. 10 mg of the above catalyst dispersed in 5 mL of deionized water was added to a round-bottom flask, followed by a mixture of 1 mmol of ammonia borane and 0.667 mmol of sodium hydroxide in 10 mL of deionized water. The performance of the catalyst in catalyzing the hydrolysis of ammonia borane is shown in Figure 1. Figure 6 , ammonia borane completely released hydrogen within 22 minutes.

[0064] It should be noted that although the present invention has been described with reference to the above embodiments, the present invention may also have other various embodiments. Without departing from the spirit and scope of the present invention, it is obvious that those skilled in the art may make various corresponding changes and modifications to the present invention, and such changes and modifications shall fall within the scope of protection of the appended claims and their equivalents.

Claims

1. A method for preparing a CoMoP ternary catalyst, characterized in that: The method comprises the following preparation steps: Step 1: adding cobalt nitrate into methanol to dissolve to obtain a transparent solution A; Step 2: Add 2-methylimidazole to methanol and dissolve it to obtain a transparent solution B; Step 3: Rapidly add solution A to solution B under stirring, continue stirring at a temperature of 20-30°C for 12-48 hours, centrifuge and wash, and then dry in a vacuum oven at 50-100°C to obtain ZIF-67; Step 4: Completely dissolve the Mo source in the solvent to obtain solution C; add the prepared ZIF-67 to solution C under stirring at 20-30°C, wherein the mass ratio of Mo atoms to ZIF-67 is 1:1-100, and the ratio of the solvent volume mL to the ZIF-67 mass mg is 0.3-0.5:1; Step 5: After mixing evenly, continue stirring at 65-80°C until the solvent is completely evaporated to obtain Mo / ZIF-67; Step 6: Control the mass ratio of Mo / ZIF-67 to sodium hypophosphite to be 1:1-1:20, maintain the temperature at 300° C. for 6 h under a nitrogen atmosphere, and then increase the temperature to 600° C. and maintain it for 1 h to obtain a CoMoP ternary catalyst.

2. The method for preparing a CoMoP ternary catalyst according to claim 1, wherein: In step 1, the ratio of the molar amount mol of the cobalt nitrate to the volume L of methanol is 1:10-20.

3. The method for preparing a CoMoP ternary catalyst according to claim 1, wherein: In step 2, the ratio of the molar amount mol of the 2-methylimidazole to the volume L of methanol is 1:0.8-2.

4. The method for preparing a CoMoP ternary catalyst according to claim 1, wherein: In step 3, the molar ratio of cobalt nitrate in solution A to 2-methylimidazole in solution B is 1:4-5.

5. The method for preparing a CoMoP ternary catalyst according to claim 1, characterized in that: In step 4, the Mo source is any one of molybdenum chloride, molybdenum nitrate or molybdenum acetylacetonate.

6. The method for preparing a CoMoP ternary catalyst according to claim 1, characterized in that: In step 4, the solvent is methanol or ethanol.

7. The method for preparing a CoMoP ternary catalyst according to claim 1, characterized in that: Step 6: The heating rate of phosphating in nitrogen atmosphere is 1-5°C / min.

8. A CoMoP ternary catalyst prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the CoMoP ternary catalyst according to claim 8 in catalyzing the hydrolysis of ammonia borane to produce hydrogen.

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