A nickel-based catalyst, a preparation method and application thereof

Abstract

The application discloses a nickel-based catalyst and a preparation method and application thereof, and belongs to the field of catalysts. The nickel-based catalyst comprises an active component, a carrier component and an auxiliary component; the active component is nickel; the carrier component is at least one selected from magnesium, strontium, lanthanum, cerium, praseodymium, neodymium and samarium; the auxiliary component is at least one selected from calcium, barium, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium and samarium; and the carrier component and the auxiliary component are not the same. The catalyst is low in cost, simple in preparation, high in dispersion and stability, and good in catalytic performance, and can be applied to catalytic ammonia decomposition for hydrogen production.

Description

Technical Field

[0001] This application relates to a nickel-based catalyst, its preparation method, and its application, and belongs to the field of catalysts. Background Technology

[0002] Over the past few decades, the term "hydrogen economy" has gained increasing importance. Hydrogen is an environmentally friendly, CO2-free... x It is an energy carrier with high gravimetric energy density. However, other characteristics, such as its low volumetric energy density (1500 W·h·kg for liquid H2), are also present. -1 The gaseous H2 concentration is 800 W·h·kg⁻¹ -1 Its high flammability and low boiling point hinder its further development.

[0003] Currently, hydrogen production and storage technologies based on fossil fuels and cycloalkane series are developing rapidly, but the resulting hydrogen contains trace amounts of CO. x This can lead to carbon buildup on palladium films and poisoning of electrode catalysts, reducing their lifespan. Compared to the former, ammonia has several advantages in terms of storage potential: its volumetric energy density is 3000 W·h·kg⁻¹. -1 Ammonia has a hydrogen capacity of 17.8 wt%. Since J. Priestley discovered ammonia in 1774 and industrially synthesized it in 1908 using the famous Haber-Bosch process, ammonia has been one of the world's most produced chemicals. Not only is its production mature, but ammonia is also widely used in countries such as China, the United States, and Russia for distribution and transportation via pipelines. Trucks, trains, and ships are also used worldwide to transport this important commodity. Furthermore, ammonia liquefaction is inexpensive and can be achieved by compressing it to 10 bar at room temperature or by cooling it to -33°C at atmospheric pressure. In addition, the volumetric hydrogen density provided by liquefied ammonia is 45% higher than that of liquefied hydrogen. Finally, this chemical is stable, leaks are easily detected, and it offers carbon-free energy storage, making it one of the most promising hydrogen supply routes currently available.

[0004] Existing catalysts used in ammonia decomposition for hydrogen production mainly include noble metal catalysts (Ir, Pt, etc.) represented by Ru and transition metal catalysts represented by Fe, Ni, and Co. Ru-based catalysts have the best catalytic performance but are expensive, while Fe and Ni-based catalysts are inexpensive but have lower catalytic activity, requiring temperatures above 700℃ to achieve high conversion rates. Therefore, there is a need to develop a non-noble metal catalyst that can efficiently decompose hydrogen at low temperatures, generating hydrogen efficiently at 450–550℃, and applying it to palladium membrane separation of high-purity hydrogen. Summary of the Invention

[0005] To improve the above-mentioned technical problems, this invention aims to provide a nickel-based ammonia decomposition catalyst and its preparation method, and to apply them. It can solve at least one of the following technical problems: (1) the problem that the conversion rate of nickel-based catalysts is not high below 700℃; (2) the catalyst will agglomerate after high temperature and high space velocity test; (3) the problem that high-performance catalysts deactivate quickly; (4) the catalyst preparation is complicated, costly, and difficult to scale up production.

[0006] To achieve the above objectives, this application provides a method for preparing a nickel solid solution catalyst, wherein nickel is the main component, nickel and metal oxides are used as the solid solution support, and an additive is added, all of which are uniformly dispersed in the catalyst, wherein the nickel content is 10-50 wt.%. The ammonia decomposition catalyst obtained by this method can decompose ammonia into hydrogen and nitrogen at a relatively low temperature (400-550℃) and has good stability.

[0007] According to a first aspect of this application, a nickel-based catalyst is provided. This nickel-based catalyst uses a nickel solid solution as a support and active component, and barium or rare earth oxides as a promoter. The catalyst exhibits a lamellar honeycomb structure with uniform elemental distribution, wherein nickel accounts for 10–50 wt.% of the total catalyst mass.

[0008] A nickel-based catalyst, the nickel-based catalyst comprising an active component, a support component, and an auxiliary component;

[0009] The active component is nickel;

[0010] The carrier component is selected from at least one of magnesium, strontium, lanthanum, cerium, praseodymium, neodymium, and samarium;

[0011] The auxiliary component is selected from at least one of calcium, barium, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, and samarium;

[0012] Furthermore, the carrier component and the auxiliary component are not the same at the same time.

[0013] Optionally, nickel accounts for 10-50% of the total mass of the catalyst;

[0014] The support component accounts for 10-30% of the total mass of the catalyst.

[0015] Optionally, nickel accounts for 30-40% of the total mass of the catalyst;

[0016] The support component accounts for 15-20% of the total mass of the catalyst.

[0017] Optionally, the nickel-based catalyst has a solid solution structure. Before reduction, the catalyst needs to form a solid solution structure of NixMyOz (where M refers to the support elements magnesium, strontium, lanthanum, cerium, praseodymium, neodymium, and samarium).

[0018] Optionally, the nickel-based catalyst has a particle size of 1–30 nm and a specific surface area of ​​30–300 m².2 / g.

[0019] According to a second aspect of this application, a method for preparing a nickel-based catalyst is provided. The present invention utilizes a co-deposition method, a hydrothermal method, and a grinding method to prepare a catalyst precursor. The obtained solid is washed, dried, ball-milled and calcined, and finally reduced under a reducing atmosphere to obtain the catalyst.

[0020] The preparation method of the nickel-based catalyst described above includes the following steps:

[0021] A precipitant, nickel salt solution, carrier metal salt solution, and auxiliary metal salt solution are added to a reactor for reaction, aging, washing, drying, ball milling, and calcination to obtain a precursor, which is then reduced to obtain the nickel-based catalyst.

[0022] Optionally, the nickel salt is selected from at least one of nickel-related nitrates, acetates, chlorides, and oxalates;

[0023] The carrier metal salt is selected from at least one of the corresponding nitrate, acetate, and oxalate salts;

[0024] The auxiliary metal salt is selected from at least one of the corresponding nitrate, acetate, and oxalate salts;

[0025] The precipitant is selected from at least one of ammonium carbonate, ammonium bicarbonate, ammonia, potassium hydroxide, and sodium hydroxide.

[0026] Optionally, the nickel salt is selected from at least one of nickel nitrate, nickel acetate, nickel chloride, and nickel oxalate.

[0027] Optionally, the total molar ratio of the precipitant to the metal salt is 0.5 to 5:1.

[0028] Optionally, the solvent is at least one of water, methanol, ethanol, ethylene glycol, and glycerol.

[0029] Optionally, when the precipitant and the metal salt solution are mixed by titration, the titration reaction time is 1 to 14 hours and the reaction temperature is 20 to 80°C.

[0030] When the precipitant and metal salt solution are added to the reactor for hydrothermal reaction, the hydrothermal reaction time is 1 to 12 hours and the hydrothermal reaction temperature is 20 to 110°C.

[0031] The reaction methods include co-precipitation and hydrothermal methods.

[0032] Optionally, the aging time is 6 to 72 hours.

[0033] Optionally, the drying temperature is 90–150°C, and the time is 1–24 hours.

[0034] Optionally, the ball milling time is 2 to 10 hours.

[0035] Optionally, the calcination temperature is 200–800°C, and the calcination time is 2–10 hours.

[0036] Optionally, the reduction includes: under a reducing atmosphere, at a temperature of 300–800°C, for a time of 30–360 min.

[0037] Optionally, the reducing atmosphere is ammonia, hydrogen, or a mixture of hydrogen and an inert gas, wherein the volume content of hydrogen in the mixture is 1-90%.

[0038] Optionally, the inert gas is selected from at least one of helium, neon, and argon.

[0039] In one preferred embodiment, the preparation method of the nickel-based catalyst includes:

[0040] (1) According to the requirements of nickel loading, prepare nickel salt solutions with different contents, and add them to the above-mentioned salt solutions that can form solid solutions and stir to form nickel precursor solutions; at the same time, prepare alkaline precipitant solvent of a certain concentration and stir as well.

[0041] (2) React the solutions of both by co-precipitation or hydrothermal method;

[0042] (3) Seal and let stand or stir to age the product obtained in step (2);

[0043] (4) Centrifuge the product obtained in step (3);

[0044] (5) Dry the product obtained in step (4) in an oven;

[0045] (6) The product obtained in step (5) is ball-milled;

[0046] (7) The product obtained in step (6) is calcined in a muffle furnace;

[0047] (8) The product obtained in step (7) is reduced under a reducing atmosphere to obtain a nickel solid solution catalyst.

[0048] According to a third aspect of this application, the application of the aforementioned nickel-based catalyst in ammonia decomposition for hydrogen production is provided. This nickel-based catalyst, used as an ammonia decomposition catalyst, produces COx-free hydrogen (X = 1 or 2).

[0049] The application of the nickel-based catalysts described above in the ammonia decomposition for hydrogen production.

[0050] According to a fourth aspect of this application, the application of the aforementioned nickel-based catalyst in storage in non-air and carbon dioxide gases is provided. This nickel-based catalyst is suitable for storage in non-air and carbon dioxide gases because the oxides generated by the promoter readily react with water and carbon dioxide in the air.

[0051] Applications of the nickel-based catalysts described above in storage in non-air and carbon dioxide gases.

[0052] The beneficial effects that this application can produce include:

[0053] The nickel-based catalyst provided in this application is a low-temperature, high-efficiency catalyst for hydrogen production from ammonia decomposition. It has a solid solution structure, and due to its small particle size, it can achieve high dispersion of active sites and prevent agglomeration.

[0054] This nickel-based catalyst is prepared by co-precipitation or hydrothermal methods. The preparation process is simple and easy to operate, enabling large-scale, systematic preparation and industrial production. It utilizes common and inexpensive reagents.

[0055] This nickel-based catalyst exhibits good catalytic performance and stability, effectively improving the conversion rate of ammonia decomposition and is CO-free. x The hydrogen gas is uniformly dispersed. When used in the ammonia decomposition reaction, its catalytic activity is comparable to that of currently available commercial ruthenium-based catalysts. In the pure ammonia reaction, the gas space velocity is 30000 mL·g⁻¹. -1 ·h -1 Under certain conditions, ammonia can be almost completely converted into nitrogen and hydrogen at 550℃. The gas hourly space velocity (GHSV) of pure ammonia is 120,000 mL / g. -1 ·h -1 Under these conditions, the ammonia decomposition conversion rate is still 64%. Attached Figure Description

[0056] Figure 1 The nickel solid solution catalyst with 35 wt.% Ni prepared in Example 6 of this invention has a pure ammonia space velocity of 30000 mL·g. -1 ·h -1 Stability test of ammonia decomposition at 550℃.

[0057] Figure 2 The experiment on the decomposition of pure ammonia at 550°C under different space velocities was conducted using the 35wt.%Ni nickel solid solution catalyst prepared in Example 6 of this invention.

[0058] Figure 3 This is an electron microscope image of the 35 wt.% Ni nickel solid solution catalyst prepared in Example 6 of the present invention.

[0059] Figure 4 This is an EDS image of the 35 wt.% Ni nickel solid solution catalyst prepared in Example 6 of the present invention.

[0060] Figure 5 The image shows the XRD pattern of the 35 wt.% Ni nickel solid solution catalyst prepared in Example 6 of this invention. Detailed Implementation

[0061] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0062] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0063] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0064] It should be noted that all figures appearing in the specification and claims of this invention (such as active components, temperature and time, gas conversion rate, etc.) should not be interpreted as absolutely precise values. Due to the standard deviation of measurement techniques, the measured values ​​inevitably contain a certain degree of experimental error.

[0065] The analysis method in the embodiments of this application is as follows:

[0066] Transmission electron microscopy (TEM) was performed at 100 kV on a FEI Talos F200x microscope. Elemental mapping analysis (EDS) of the samples was obtained using scanning transmission electron microscopy (STEM) mode at 200 kV on a Philips Tecnai F20 instrument.

[0067] XRD analysis was performed on an Empyrean-100 powder diffractometer under Cu Kα radiation (λ = 1.5418°A, 40 kV, 40 mA) in the scanning range of 20°–80°.

[0068] Nitrogen adsorption-desorption tests were performed on QUADRASORB SI at 77 K. All study products were degassed under vacuum at 200 °C for 100 min prior to the test. Specific surface area was calculated according to the Brunauer, Emmett, and Teeler (BET) method.

[0069] Example 1

[0070] The catalyst preparation method in this embodiment includes the following steps:

[0071] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of ethanol. While stirring vigorously, add 5.103g of cerium nitrate and 0.905g of calcium nitrate. Continue stirring the mixed solution for 0.5h.

[0072] Step 2: Dissolve 5.3846g of ammonium carbonate in 50mL of ethanol and stir for 0.5h until completely dissolved;

[0073] Step 3: Add both to a 250mL beaker using a peristaltic pump. After titration (total titration time is 2 hours), age for 24 hours.

[0074] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0075] Step 5: Solid ball mill the precursor for 2 hours;

[0076] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0077] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0078] Example 2

[0079] The catalyst preparation method in this embodiment includes the following steps:

[0080] Step 1: Preparation of metal salt solution: Weigh 6.677g of nickel nitrate and dissolve it in 50mL of water. While stirring vigorously, add 5.903g of magnesium nitrate and 0.905g of barium nitrate. Continue stirring the mixed solution for 0.5h.

[0081] Step 2: Dissolve 5.3846g of ammonium carbonate in 50mL of ethanol and stir for 0.5h until completely dissolved;

[0082] Step 3: Add the two ingredients to a 200mL hydrothermal reactor using a hydrothermal method, and maintain the reaction at 110℃ for 6 hours. After the reaction is complete, allow the mixture to cool to room temperature and age for 36 hours.

[0083] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 90°C for 48 hours.

[0084] Step 5: Solid ball mill the precursor for 2 hours;

[0085] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0086] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0087] Example 3

[0088] The catalyst preparation method in this embodiment includes the following steps:

[0089] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of ethanol. While stirring vigorously, add 4.103g of magnesium nitrate and 0.905g of yttrium nitrate. Continue stirring the mixed solution for 0.5h.

[0090] Step 2: Dissolve 5.3846g of ammonium carbonate in 50mL of water and stir for 0.5h until completely dissolved;

[0091] Step 3: Add both to a 250mL beaker using a peristaltic pump. After titration (total titration time is 2 hours), age for 12 hours.

[0092] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0093] Step 5: Solid ball mill the precursor for 2 hours;

[0094] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0095] Step 7: Load the precursor powder into the reactor and reduce it with 10% H2 / N2 for 250 min to obtain the reduced nickel solid solution catalyst.

[0096] Example 4

[0097] The catalyst preparation method in this embodiment includes the following steps:

[0098] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of water. While stirring vigorously, add 4.103g of strontium nitrate and 0.905g of lanthanum nitrate. Continue stirring the mixed solution for 0.5h.

[0099] Step 2: Dissolve 5.3846g of ammonium carbonate in 50mL of water and stir for 0.5h until completely dissolved;

[0100] Step 3: Add the two ingredients to a 200mL hydrothermal reactor using a hydrothermal method, and maintain the reaction at 110℃ for 6 hours. After the reaction is complete, allow the mixture to cool to room temperature and age for 12 hours.

[0101] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0102] Step 5: Solid ball mill the precursor for 2 hours;

[0103] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0104] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0105] Example 5

[0106] The catalyst preparation method in this embodiment includes the following steps:

[0107] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel acetate and dissolve it in 50mL of ethanol. While stirring vigorously, add 4.103g of cerium acetate and 0.905g of lanthanum nitrate. Continue stirring the mixed solution for 0.5h.

[0108] Step 2: Dissolve 5.3846g of ammonium carbonate in 50mL of ethanol and stir for 0.5h until completely dissolved;

[0109] Step 3: Add both to a 250mL beaker using a peristaltic pump. After titration (total titration time is 2 hours), age for 24 hours.

[0110] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0111] Step 5: Solid ball mill the precursor for 2 hours;

[0112] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0113] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0114] Example 6

[0115] The catalyst preparation method in this embodiment includes the following steps:

[0116] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of water. While stirring vigorously, add 4.103g of strontium nitrate and 0.905g of scandium nitrate. Continue stirring the mixed solution for 0.5h.

[0117] Step 2: Dissolve 5.3846g of ammonium carbonate in 50mL of water and stir for 0.5h until completely dissolved;

[0118] Step 3: Add both to a 250mL beaker using a peristaltic pump. After titration (total titration time is 2 hours), age for 12 hours.

[0119] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 150°C for 24 hours.

[0120] Step 5: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0121] Step 6: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0122] Example 7

[0123] The catalyst preparation method in this embodiment includes the following steps:

[0124] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of water. While stirring vigorously, add 4.103g of magnesium nitrate and 0.905g of lanthanum nitrate. Continue stirring the mixed solution for 0.5h.

[0125] Step 2: Dissolve 5.3846g of ammonium bicarbonate in 50mL of water and stir for 0.5h until completely dissolved;

[0126] Step 3: Add both to a 250mL beaker using a peristaltic pump. After titration (total titration time is 2 hours), age for 24 hours.

[0127] Step 4: After centrifugation, washing, and filtration, the aged solution is dried at 110°C for 10 hours.

[0128] Step 5: Solid ball mill the precursor for 2 hours;

[0129] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0130] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0131] Example 8

[0132] The catalyst preparation method in this embodiment includes the following steps:

[0133] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of ethanol. While stirring vigorously, add 4.103g of praseodymium nitrate and 0.905g of cerium nitrate. Continue stirring the mixed solution for 0.5h.

[0134] Step 2: Dissolve 5.3846g of ammonium bicarbonate in 50mL of water and stir for 0.5h until completely dissolved;

[0135] Step 3: Add the two ingredients to a 200mL hydrothermal reactor using a hydrothermal method, and maintain the reaction at 110℃ for 6 hours. After the reaction is complete, allow the mixture to cool to room temperature and age for 12 hours.

[0136] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 110℃ for 24 hours;

[0137] Step 5: Solid ball mill the precursor for 2 hours;

[0138] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0139] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0140] Example 9

[0141] The catalyst preparation method in this embodiment includes the following steps:

[0142] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of ethanol. While stirring vigorously, add 4.103g of magnesium nitrate and 0.505g of lanthanum nitrate. Continue stirring the mixed solution for 0.5h.

[0143] Step 2: Dissolve 3.3846g of ammonium carbonate in 50mL of ethanol and stir for 0.5h until completely dissolved;

[0144] Step 3: Add both to a 250mL beaker using a peristaltic pump. After titration (total titration time is 2 hours), age for 24 hours.

[0145] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0146] Step 5: Solid ball mill the precursor for 2 hours;

[0147] Step Six: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0148] Step 7: Load the precursor powder into the reactor and reduce it with 5% H2 / N2 for 240 min to obtain the reduced nickel solid solution catalyst.

[0149] Example 10

[0150] The catalyst preparation method in this embodiment includes the following steps:

[0151] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of ethanol. While stirring vigorously, add 4.103g of magnesium acetate and 0.905g of lanthanum nitrate. Continue stirring the mixed solution for 0.5h.

[0152] Step 2: Dissolve 5.3846g of ammonium bicarbonate in 50mL of 25wt% ammonia water and stir for 0.5h until completely dissolved;

[0153] Step 3: Add both to a 250mL beaker using a peristaltic pump. After titration (total titration time is 2 hours), age for 24 hours.

[0154] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0155] Step 5: Place the solid in a muffle furnace and bake at 500℃ for 2 hours;

[0156] Step 6: Solid ball mill the precursor for 2 hours;

[0157] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0158] Example 11

[0159] The catalyst preparation method in this embodiment includes the following steps:

[0160] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of water. While stirring vigorously, add 4.103g of magnesium nitrate and 0.905g of lanthanum nitrate. Continue stirring the mixed solution for 0.5h.

[0161] Step 2: Dissolve 5.3846g of ammonium bicarbonate in 50mL of ammonia water and stir for 0.5h until completely dissolved;

[0162] Step 3: Add both to a 200mL hydrothermal reactor using a hydrothermal method, react at 90℃ for 4 hours, and then age for 12 hours after completion;

[0163] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0164] Step 5: Solid ball mill the precursor for 2 hours;

[0165] Step 6: Place the solid in a muffle furnace and bake at 500℃ for 5 hours.

[0166] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0167] Example 12

[0168] The catalyst preparation method in this embodiment includes the following steps:

[0169] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of water. While stirring vigorously, add 4.103g of magnesium nitrate and 0.905g of barium nitrate. Continue stirring the mixed solution for 0.5h.

[0170] Step 2: Dissolve 5.3846g of ammonium bicarbonate in 50mL of ammonia water and stir for 0.5h until completely dissolved;

[0171] Step 3: Add both to a 200mL hydrothermal reactor using a hydrothermal method, react at 90℃ for 4 hours, and then age for 12 hours after completion;

[0172] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0173] Step 5: Solid ball mill the precursor for 2 hours;

[0174] Step 6: Place the solid in a muffle furnace and bake at 500℃ for 5 hours.

[0175] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0176] Example 13

[0177] The catalyst preparation method in this embodiment includes the following steps:

[0178] Step 1: Preparation of metal salt solution: Weigh 4.677g of nickel nitrate and dissolve it in 50mL of water. While stirring vigorously, add 4.103g of strontium nitrate and 0.905g of yttrium nitrate. Continue stirring the mixed solution for 0.5h.

[0179] Step 2: Dissolve 5.3846g of ammonium bicarbonate in 50mL of ammonia water and stir for 0.5h until completely dissolved;

[0180] Step 3: Add both to a 200mL hydrothermal reactor using a hydrothermal method, react at 90℃ for 4 hours, and then age for 12 hours after completion;

[0181] Step 4: After aging, the solution is centrifuged, washed, filtered, and then dried at 100℃ for 24 hours;

[0182] Step 5: Solid ball mill the precursor for 2 hours;

[0183] Step 6: Place the solid in a muffle furnace and bake at 500℃ for 5 hours.

[0184] Step 7: Load the precursor powder into the reactor and reduce it with 25% H2 / N2 for 150 min to obtain the reduced nickel solid solution catalyst.

[0185] Characterization test

[0186] The nickel solid solution catalysts prepared in the above examples were characterized and analyzed.

[0187] Taking the nickel solid solution catalyst prepared in Example 6 (in which the mass content of Ni is 35 wt.%) as an example, Figure 3 The electron microscope images show that the particle size of the catalyst is 1–15 nm. Figure 4 The EDS image shows that the catalyst exhibits a plate-like honeycomb structure with uniform elemental distribution. Figure 5The XRD pattern shows that the catalyst consists of a nickel-magnesium solid solution. Nitrogen adsorption-desorption tests revealed a specific surface area of ​​30–300 m². 2 / g.

[0188] Application testing

[0189] Taking the 35 wt.% Ni nickel solid solution catalyst prepared in Example 6 as an example, at a pure ammonia space velocity of 30000 mL·g -1 ·h -1 The stability test of ammonia decomposition at 550℃ yielded the following results: Figure 1 As shown in the figure, it can be seen that its performance remains stable after 240 hours. The results of ammonia decomposition experiments at 550℃ under pure ammonia conditions with different space velocities are as follows: Figure 2 As shown, the gas hourly space velocity (GHSV) of ammonia is 30000 mL·g⁻¹. -1 ·h -1 Under certain conditions, ammonia can be almost completely converted into nitrogen and hydrogen at 550℃. The gas hourly space velocity (GHSV) of pure ammonia is 120,000 mL / g. -1 ·h -1 Under these conditions, the ammonia decomposition conversion rate is still 64%.

[0190] The preparation method of this invention is simple, and it uses low-cost nickel oxide solid solution as active site and support. The prepared catalyst has the advantages of good metal dispersion, high catalytic activity and good stability, and can be used in the catalytic decomposition of ammonia to produce hydrogen.

[0191] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A nickel-based catalyst, characterized in that, The nickel-based catalyst comprises an active component, a support component, and an auxiliary component; The active component is nickel; The carrier component is selected from at least one of magnesium, strontium, lanthanum, cerium, praseodymium, neodymium, and samarium; The auxiliary component is selected from at least one of calcium, barium, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, and samarium; Furthermore, the carrier component and the auxiliary component are not the same at the same time.

2. The nickel-based catalyst according to claim 1, characterized in that, Nickel accounts for 10-50% of the total mass of the catalyst; The support component accounts for 10-30% of the total mass of the catalyst.

3. The nickel-based catalyst according to claim 1, characterized in that, The nickel-based catalyst has a solid solution structure.

4. The nickel-based catalyst according to claim 1, characterized in that, The nickel-based catalyst has a particle size of 1–30 nm and a specific surface area of ​​30–300 m². 2 / g.

5. The method for preparing the nickel-based catalyst according to any one of claims 1 to 4, characterized in that, The preparation method includes the following steps: A precipitant, nickel salt solution, carrier metal salt solution, and auxiliary metal salt solution are added to a reactor for reaction, aging, washing, drying, ball milling, and calcination to obtain a precursor, which is then reduced to obtain the nickel-based catalyst.

6. The preparation method according to claim 5, characterized in that, The nickel salt is selected from at least one of nickel-related nitrates, acetates, chlorides, and oxalates; The carrier metal salt is selected from at least one of the corresponding nitrate, acetate, and oxalate salts; The auxiliary metal salt is selected from at least one of the corresponding nitrate, acetate, and oxalate salts; The precipitant is selected from at least one of ammonium carbonate, ammonium bicarbonate, ammonia, potassium hydroxide, and sodium hydroxide. Preferably, the total molar ratio of the precipitant to the metal salt is 0.5 to 5:

1.

7. The preparation method according to claim 5, characterized in that, When the precipitant and metal salt solution are mixed by titration, the titration reaction time is 1 to 14 hours and the reaction temperature is 20 to 80°C. When the precipitant and metal salt solution are added to the reactor for hydrothermal reaction, the hydrothermal reaction time is 1 to 12 hours and the hydrothermal reaction temperature is 20 to 110°C.

8. The preparation method according to claim 5, characterized in that, The aging time is 6–72 hours; The roasting temperature is 200–800℃, and the roasting time is 2–10 hours. The reduction process includes: under a reducing atmosphere, at a temperature of 300–800°C, for a time of 30–360 min.

9. The application of the nickel-based catalyst according to any one of claims 1 to 4 in the ammonia decomposition for hydrogen production.

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