CN115646500B - Catalyst for producing hydrogen by ammonia decomposition and preparation method and application thereof - Google Patents
Catalyst for producing hydrogen by ammonia decomposition and preparation method and application thereof Download PDFInfo
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- CN115646500B CN115646500B CN202211352039.0A CN202211352039A CN115646500B CN 115646500 B CN115646500 B CN 115646500B CN 202211352039 A CN202211352039 A CN 202211352039A CN 115646500 B CN115646500 B CN 115646500B
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 144
- 239000003054 catalyst Substances 0.000 title claims abstract description 100
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 79
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims abstract description 77
- 239000001257 hydrogen Substances 0.000 title claims abstract description 77
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 72
- 238000000354 decomposition reaction Methods 0.000 title claims abstract description 53
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 238000006243 chemical reaction Methods 0.000 claims abstract description 61
- 229910052751 metal Inorganic materials 0.000 claims abstract description 49
- 239000002184 metal Substances 0.000 claims abstract description 49
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical group [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 47
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims abstract description 33
- 229910052747 lanthanoid Inorganic materials 0.000 claims abstract description 31
- 150000002602 lanthanoids Chemical class 0.000 claims abstract description 27
- 150000001342 alkaline earth metals Chemical class 0.000 claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 claims abstract description 21
- 239000002243 precursor Substances 0.000 claims abstract description 17
- -1 alkaline earth metal salt Chemical class 0.000 claims abstract description 16
- 150000003839 salts Chemical class 0.000 claims abstract description 13
- 239000012752 auxiliary agent Substances 0.000 claims abstract description 10
- 239000012065 filter cake Substances 0.000 claims description 75
- 239000012266 salt solution Substances 0.000 claims description 75
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 73
- 239000000243 solution Substances 0.000 claims description 67
- 239000008367 deionised water Substances 0.000 claims description 59
- 229910021641 deionized water Inorganic materials 0.000 claims description 59
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 49
- 239000002002 slurry Substances 0.000 claims description 38
- 238000010438 heat treatment Methods 0.000 claims description 35
- 230000032683 aging Effects 0.000 claims description 31
- 238000005406 washing Methods 0.000 claims description 31
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 27
- 238000001035 drying Methods 0.000 claims description 27
- 238000001914 filtration Methods 0.000 claims description 23
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 17
- KTUQUZJOVNIKNZ-UHFFFAOYSA-N butan-1-ol;hydrate Chemical group O.CCCCO KTUQUZJOVNIKNZ-UHFFFAOYSA-N 0.000 claims description 16
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Chemical compound [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 claims description 16
- 238000002156 mixing Methods 0.000 claims description 14
- 230000007935 neutral effect Effects 0.000 claims description 13
- IWOUKMZUPDVPGQ-UHFFFAOYSA-N barium nitrate Chemical compound [Ba+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O IWOUKMZUPDVPGQ-UHFFFAOYSA-N 0.000 claims description 12
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 claims description 12
- 239000002270 dispersing agent Substances 0.000 claims description 12
- 150000002815 nickel Chemical class 0.000 claims description 12
- KBJMLQFLOWQJNF-UHFFFAOYSA-N nickel(ii) nitrate Chemical group [Ni+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O KBJMLQFLOWQJNF-UHFFFAOYSA-N 0.000 claims description 11
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims description 10
- 229910052759 nickel Inorganic materials 0.000 claims description 10
- 239000002904 solvent Substances 0.000 claims description 10
- 239000000047 product Substances 0.000 claims description 9
- 239000000706 filtrate Substances 0.000 claims description 8
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical group C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000011734 sodium Substances 0.000 claims description 4
- 229910052708 sodium Inorganic materials 0.000 claims description 4
- 238000010025 steaming Methods 0.000 claims description 4
- 239000012298 atmosphere Substances 0.000 claims description 2
- 230000006378 damage Effects 0.000 claims 3
- 230000003197 catalytic effect Effects 0.000 abstract description 5
- 239000003513 alkali Substances 0.000 abstract description 3
- 239000002253 acid Substances 0.000 abstract description 2
- 239000002585 base Substances 0.000 description 25
- 238000003756 stirring Methods 0.000 description 20
- 230000000694 effects Effects 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 230000008569 process Effects 0.000 description 11
- 235000019441 ethanol Nutrition 0.000 description 10
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 description 9
- 238000001556 precipitation Methods 0.000 description 9
- 229910001388 sodium aluminate Inorganic materials 0.000 description 9
- 238000001704 evaporation Methods 0.000 description 8
- 239000011777 magnesium Substances 0.000 description 7
- 239000007788 liquid Substances 0.000 description 6
- 230000009471 action Effects 0.000 description 4
- 238000009826 distribution Methods 0.000 description 4
- 230000003993 interaction Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 239000011575 calcium Substances 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 239000002803 fossil fuel Substances 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000005915 ammonolysis reaction Methods 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 238000002390 rotary evaporation Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
Abstract
The invention provides a catalyst for producing hydrogen by ammonia decomposition, which comprises an active metal component, an alkaline earth metal component, a lanthanide metal component and an auxiliary agent, wherein a precursor of the active metal component is nickel salt, a precursor of the alkaline earth metal component is alkaline earth metal salt, a precursor of the lanthanide metal component is lanthanide metal salt, and a precursor of the auxiliary agent is meta-aluminate; the catalyst for preparing hydrogen by ammonia decomposition can effectively regulate the acid and the alkali on the surface of the catalyst and adjust the electron cloud density of active components by introducing alkaline earth metals and lanthanide metals, so that the catalytic activity and the stability of the catalyst are improved; the invention also provides a preparation method of the catalyst for preparing hydrogen by ammonia decomposition, which has mild conditions, is easy to control and can meet the requirement of industrial mass production; the invention further provides application of the catalyst for producing hydrogen by ammonia decomposition in the reaction of producing hydrogen by ammonia decomposition.
Description
Technical Field
The invention relates to the technical field of catalysis, in particular to a catalyst for producing hydrogen by ammonia decomposition, and a preparation method and application thereof.
Background
The heat value of the hydrogen energy is high, the energy utilization rate is high, the source is wide, the product after use is water, the environment pollution is not caused, and the hydrogen energy is a clean energy source with great application potential. Fossil fuels are the main raw material for large-scale hydrogen production at present, and the obtained product contains a certain amount of COx, so that the application of the fossil fuels is limitedThe cost is greatly increased in the complicated separation and purification process, and the market competitiveness of the product is reduced. The ammonia has a high volume energy density (108 Kg-H 2 /m 3 NH 3 ) And weight energy density (17.8 wt%) which is mild in transportation and storage conditions and low in hydrogen production cost, is a good hydrogen storage medium, and is expected to continuously provide low-cost clean hydrogen for chemical industry by decomposing ammonia to produce hydrogen. Noble metal catalysts exhibit good activity in ammonia decomposition reactions, but their high price limits their large-scale industrial application; the non-noble metal catalyst has considerable practical application value due to its wide source, low price and better activity.
When non-noble metal is used as the active component of the ammonia decomposition catalyst, the catalyst is limited by the activity of the metal, and the number of active sites of the catalyst is increased by increasing the amount of the active metal component of the catalyst to improve the activity of the catalyst. In addition to the main catalyst, various types of auxiliary agents are often introduced to improve the ammonia decomposition properties of the catalyst. Patent CN202110381618.7 discloses a transition metal doped ammonia decomposition catalyst, a preparation method and application thereof, wherein transition metal cobalt, iron and copper are doped to improve the dispersity of a nickel-based catalyst and reduce the size of metal particles, and the activity of the catalyst of the patent is improved to a certain extent compared with that of an unmodified catalyst, but NH is improved at 550 DEG C 3 The conversion is only 50%, and the activity of the catalyst still needs to be further improved.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide an ammonia decomposition hydrogen production catalyst, and a preparation method and application thereof, so as to solve the problems of low catalytic efficiency and instability of the ammonia decomposition hydrogen production catalyst in the prior art.
To achieve the above and other related objects, the present invention provides a catalyst for producing hydrogen by decomposing ammonia, the catalyst comprising an active metal component, an alkaline earth metal component, a lanthanide metal component and an auxiliary agent, wherein a precursor of the active metal component is a nickel salt, a precursor of the alkaline earth metal component is an alkaline earth metal salt, a precursor of the lanthanide metal component is a lanthanide metal salt, and a precursor of the auxiliary agent is a meta-aluminate.
Preferably, the nickel salt is nickel nitrate.
Preferably, the meta-aluminate is sodium meta-aluminate.
Preferably, the alkaline earth metal salt is one or more of magnesium nitrate, calcium nitrate and barium nitrate.
Preferably, the lanthanide metal salt is one or two of lanthanum nitrate and cerium nitrate.
Preferably, the nickel/aluminum molar ratio in the catalyst is 0.05-0.3; the molar ratio of nickel to alkaline earth metal is 0.25-1; the molar ratio of nickel to lanthanide metal is 10-50.
The invention also provides a preparation method of the catalyst for producing hydrogen by decomposing ammonia, which comprises the following steps:
1) After heating the base solution, adding a salt solution S1 comprising nickel salt and alkaline earth metal salt and a salt solution S2 comprising meta-aluminate into the base solution in parallel flow, reacting and aging;
2) Filtering and washing the aged product in the step 2) to obtain a filter cake;
3) Dispersing the filter cake obtained in the step 3) in a dispersing agent, and heating to obtain slurry;
4) And (3) mixing the salt solution S3 containing lanthanide metal salt with the slurry obtained in the step (4), drying and roasting to obtain the catalyst for producing hydrogen by decomposing ammonia.
Further, in step 1), the solvent of the salt solution S1 is deionized water.
Further, in step 1), the solvent of the salt solution S2 is deionized water.
Further, in step 1), the base solution is deionized water.
Further, in the step 1), the base solution is heated to 70-90 ℃.
Further, in the step 1), the volume ratio of the total volume of the salt solutions S1 and S2 to the volume of the base solution is 1:1-2.
Further, in the step 1), the pH of the base solution is controlled to 7-9 when the salt solutions S1 and S2 are added in parallel and during the aging process.
Further, in step 1), the reaction is performed in a reaction vessel.
Further, in the step 1), the aging time is 4 to 24 hours.
Further, in the step 2), the washing is to wash the filter cake with deionized water until the filtrate is neutral, and then wash the filter cake with absolute ethyl alcohol once more.
Further, in step 3), the dispersant is an n-butanol-water solution.
Further, in the step 3), the volume ratio of the dispersant to the filter cake is (1-2): 1.
Further, in the step 3), the heating temperature is 80 to 120 ℃.
Further, in the step 3), the heating time is 2 to 8 hours.
Further, in the step 4), the solvent of the salt solution S3 is ethanol-water, and the volume ratio of the ethanol to the water is 1:1-3.
Further, in step 4), the volume ratio of the salt solution S3 to the slurry is 1 to 2:1.
Further, in step 4), the drying specifically includes: spin steaming the mixed materials to obtain blocks; drying the block at 100-130 deg.c for 8-24 hr.
Further, in the step 4), the baking temperature is 600-800 ℃.
Further, in the step 4), the roasting time is 2-8 hours.
The invention also provides application of the catalyst for producing hydrogen by ammonia decomposition in the reaction of producing hydrogen by ammonia decomposition, and the catalyst for producing hydrogen by ammonia decomposition is used in H before the reaction of producing hydrogen by ammonia decomposition 2 /N 2 Pre-reducing for 1-3 h at 600-800 ℃.
As described above, the present invention has the following advantageous effects:
1) The catalyst for preparing hydrogen by ammonia decomposition of the invention adopts alkaline earth metal as a promoter, can effectively regulate and control the acidity and alkalinity of the catalyst surface and regulate NH 3 Adsorption and desorption strength on the surface of the catalyst, promote NH 3 Transfer between active site and carrier to raise catalytic activitySex.
2) The catalyst for preparing hydrogen by ammonia decomposition of the invention adjusts the electron cloud density of the active component by introducing lanthanide metal, enhances the interaction between metal and carrier, reduces the reaction temperature while improving the activity, and promotes the stability of the catalyst.
3) The preparation method of the catalyst for preparing hydrogen by ammonia decomposition is beneficial to reducing the concentration of metal ions, avoids the growth of crystals in the aging process, has high dispersity of active metals and narrow particle size distribution, and thus increases the number of active sites.
4) The preparation method of the catalyst for preparing hydrogen by ammonia decomposition has mild conditions, is easy to control and can meet the requirement of industrial mass production.
Drawings
FIG. 1 shows the activity curve of the catalyst prepared in example 1 of the present invention in the reaction of producing hydrogen by decomposing ammonia.
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Please refer to the accompanying drawings. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
The invention provides a catalyst for producing hydrogen by ammonia decomposition, which comprises an active metal component, an alkaline earth metal component, a lanthanide metal component and an auxiliary agent, wherein a precursor of the active metal component is nickel salt, a precursor of the alkaline earth metal component is alkaline earth metal salt, a precursor of the lanthanide metal component is lanthanide metal salt, and a precursor of the auxiliary agent is meta-aluminate.
The catalyst for preparing hydrogen by ammonia decomposition of the invention effectively regulates and controls the acid and the alkali of the catalyst surface by introducing alkaline earth metal into nickel salt, and regulates NH 3 Adsorption and desorption strength on the surface of the catalyst, promote NH 3 The catalyst is transferred between active sites and a composite metal oxide carrier formed by alkaline earth metal and aluminum, so that the catalytic activity is improved, meanwhile, the introduced lanthanide metal can adjust the electron cloud density of active components, enhance the interaction between metal and carrier, reduce the reaction temperature while improving the activity, promote the stability of the catalyst, the added meta-aluminate is alkaline after being dissolved in water, reacts with nickel salt and alkaline earth metal to generate corresponding metal hydroxide precipitate, and aluminum in sodium meta-aluminate is also precipitated at the same time, so that the finally prepared catalyst contains active metal and alkaline earth metal as well as auxiliary agent alumina, and the main functions of the catalyst are to adjust the acid-alkali property and the interaction between metal carriers of the catalyst, and improve the sintering resistance and carbon deposition resistance of the catalyst.
In the catalyst for producing hydrogen by ammonia decomposition, nickel salt is nickel nitrate.
The meta-aluminate is sodium meta-aluminate. The molar ratio of nickel to aluminum in the catalyst is 0.05-0.3. For example, 0.05 to 0.1, 0.1 to 0.15, 0.15 to 0.2, 0.2 to 0.25 or 0.25 to 0.3.
The alkaline earth metal salt is one or more of magnesium nitrate, calcium nitrate and barium nitrate. The molar ratio of nickel to alkaline earth metal in the catalyst is 0.25-1. For example, 0.25 to 0.35, 0.35 to 0.45, 0.45 to 0.55, 0.55 to 0.65, 0.65 to 0.75, 0.75 to 0.85, 0.85 to 0.95 or 0.95 to 1.
The lanthanide metal salt is one or two of lanthanum nitrate and cerium nitrate. The molar ratio of nickel to lanthanide metal in the catalyst is 10-50. For example, 10 to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45 or 45 to 50.
The second aspect of the invention provides a preparation method of the catalyst for producing hydrogen by decomposing ammonia, which comprises the following steps:
1) After heating the base solution, adding a salt solution S1 comprising nickel salt and alkaline earth metal salt and a salt solution S2 comprising meta-aluminate into the base solution in parallel flow, reacting and aging;
2) Filtering and washing the aged product in the step 2) to obtain a filter cake;
3) Dispersing the filter cake obtained in the step 3) in a dispersing agent, and heating to obtain slurry;
4) And (3) mixing the salt solution S3 containing lanthanide metal salt with the slurry obtained in the step (4), drying and roasting to obtain the catalyst for producing hydrogen by decomposing ammonia.
In the preparation method of the catalyst for producing hydrogen by ammonia decomposition, in the step 1), the solvent of the salt solution S1 is deionized water.
The solvent of the salt solution S2 is deionized water.
The molar ratio of the nickel salt to the alkaline earth metal element in the alkaline earth metal salt is 0.25-1. For example, 0.25 to 0.35, 0.35 to 0.45, 0.45 to 0.55, 0.55 to 0.65, 0.65 to 0.75, 0.75 to 0.85, 0.85 to 0.95 or 0.95 to 1.
The molar ratio of the nickel salt to the aluminum element in the meta-aluminate is 0.05-0.3. For example, 0.05 to 0.1, 0.1 to 0.15, 0.15 to 0.2, 0.2 to 0.25 or 0.25 to 0.3.
The base solution is deionized water. The base solution is heated to 70-90 ℃. For example, 10 to 80℃or 80 to 90 ℃. In a preferred embodiment of the invention, the base liquid is heated to 80 ℃.
The volume ratio of the total volume of the salt solutions S1 and S2 to the volume of the base solution is 1:1-2. For example, 1:1 to 1.2, 1:1.2 to 1.4, 1:1.4 to 1.6, 1:1.6 to 1.8 or 1:1.8 to 2.
When the salt solutions S1 and S2 are added in parallel and during the aging process, the pH of the base solution is controlled to be 7-9. The pH of the base solution can be controlled to be 7-8 or 8-9.
The reaction is carried out in a reaction kettle. The aging time is 4-24 hours. For example, 4 to 8 hours, 8 to 12 hours, 12 to 16 hours, 16 to 20 hours or 20 to 24 hours.
The specific process of the step 1) is as follows: adding base solution into a reaction kettle, heating to 70-90 ℃, adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, controlling the pH of the base solution to be 7-9 in the dripping process, continuously stirring after the dripping is finished, stopping stirring for aging after 0.5-2.0 h, and controlling the pH in the process to be 7-9.
In the preparation method of the catalyst for producing hydrogen by ammonia decomposition, in the step 2), the filter cake is washed by deionized water until the filtrate is neutral, and then the filter cake is washed once again by absolute ethyl alcohol.
Wherein the volume ratio of the absolute ethyl alcohol to the filter cake is (0.5-2): 1. For example, (0.5-1): 1, (1-1.5): 1 or (1.5-2): 1.
The specific process of the step 2) is as follows: filtering the aged product in the step 1), washing the product with deionized water until the filtrate is neutral, washing the filter cake once with absolute ethyl alcohol, and filtering to obtain the filter cake.
In the preparation method of the catalyst for producing hydrogen by ammonia decomposition, in the step 3), the dispersing agent is n-butanol-water solution. The volume ratio of the n-butanol to the water in the n-butanol-water solution is 1 (0.01-0.5). For example, 1 (0.01 to 0.05), 1 (0.05 to 0.1), 1 (0.1 to 0.15), 1 (0.15 to 0.2), 1 (0.2 to 0.25), 1 (0.25 to 0.3), 1 (0.3 to 0.35), 1 (0.35 to 0.4), 1 (0.4 to 0.45) or 1 (0.45 to 0.5).
The volume ratio of the dispersant to the filter cake is (1-2): 1. For example, (1-1.2): 1, (1.2-1.4): 1, (1.4-1.6): 1, (1.6-1.8): 1 or (1.8-2): 1.
Heating to 80-120 ℃. For example, 80 to 90 ℃, 90 to 100 ℃, 100 to 110 ℃ or 110 to 120 ℃. The heating time is 2-8 h. For example, 2 to 3 hours, 3 to 4 hours, 4 to 5 hours, 5 to 6 hours, 6 to 7 hours or 7 to 8 hours.
The specific process of the step 3) is as follows: and (3) dispersing the filter cake obtained in the step (2) again by using a dispersing agent, and heating to 80-120 ℃ and keeping for 2-8 h to obtain slurry.
In the preparation method of the catalyst for producing hydrogen by ammonia decomposition, in the step 4), the solvent of the salt solution S3 is ethanol-water, and the volume ratio of the ethanol to the water is 1:1-3. The volume ratio of ethanol to water can be 1:1-2 or 1:2-3.
The molar ratio of the nickel salt to the lanthanide metal element in the lanthanide metal salt is 10-50. For example, 10 to 15, 15 to 20, 20 to 25, 25 to 30, 30 to 35, 35 to 40, 40 to 45 or 45 to 50.
The volume ratio of the salt solution S3 to the slurry is 1-2:1.
The drying specifically comprises the following steps: spin steaming the mixed materials to obtain blocks; drying the block at 100-130 deg.c for 8-24 hr. The drying temperature may be 100 to 110 ℃, 110 to 120 ℃ or 120 to 130 ℃. In a preferred embodiment of the invention, the drying temperature is 120 ℃. The drying time can be 8-12 h, 12-16 h, 16-20 h or 20-24 h. In a preferred embodiment of the invention, the drying time is 12 hours.
The roasting temperature is 600-800 ℃. For example 600 to 650 ℃, 650 to 700 ℃,700 to 750 ℃ or 750 to 800 ℃. In a preferred embodiment of the invention, the firing temperature is 700 ℃. The roasting time is 2-8 h. For example, 2 to 3 hours, 3 to 4 hours, 4 to 5 hours, 5 to 6 hours, 6 to 7 hours or 7 to 8 hours. In a preferred embodiment of the invention, the calcination time is 4 hours.
The specific process of the step 4) is as follows: uniformly mixing the slurry obtained in the step 3) with a salt solution S3 comprising lanthanide metal salt, then spin-evaporating the mixture at 80-120 ℃ in a rotary evaporator to obtain a block, drying the block at 100-130 ℃ in a drying oven for 8-24 h, and roasting the block at 600-800 ℃ in a roasting furnace for 2-8 h to obtain the catalyst for producing hydrogen by ammonia decomposition.
The preparation method of the catalyst for preparing hydrogen by ammonia decomposition comprises the steps of impregnating a precursor prepared by adopting a coprecipitation method with a certain amount of rare earth metal through n-butyl alcohol distillation treatment and rotary evaporation, wherein the catalyst has high metal component dispersity, reasonable pore size distribution and moderate acting force between metal and a carrier, so that the catalyst has excellent low-temperature activity and good stability; the preparation method of the catalyst for preparing hydrogen by ammonia decomposition has mild conditions, is easy to control, can meet the requirement of industrial mass production, is beneficial to reducing the concentration of metal ions, avoids the growth of crystals in the aging process, has high dispersity of active metals and narrow particle size distribution, thereby increasing the number of active sites and improving the catalytic efficiency.
The third aspect of the invention provides an application of the catalyst in the hydrogen production reaction by ammonia decomposition, wherein before the ammonia decomposition reaction, the catalyst is used for hydrogen production by ammonia decomposition in H 2 /N 2 Pre-reducing for 1-3 h at 600-800 ℃. The pre-reduction temperature may be 600 to 650 ℃, 650 to 700 ℃,700 to 750 ℃ or 750 to 800 ℃. The pre-reduction time can be 1-2 h or2-3 h. In a preferred embodiment of the invention, the catalyst for producing hydrogen by ammonia decomposition is in the presence of H prior to the ammonia decomposition reaction 2 /N 2 Pre-reducing for 1h at 700 ℃.
Example 1
According to Ni 2+ /Mg 2+ Adding nickel nitrate and magnesium nitrate into 100mL deionized water according to the molar ratio of 0.5 to prepare a salt solution S1, and mixing according to Ni 2+ /Al 3+ Sodium aluminate is dissolved in 200mL deionized water to prepare salt solution S2 with the molar ratio of 0.1; adding 450mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the pH value of the kettle solution in the precipitation reaction process to be 7-9; stirring for 1h after the dripping is finished, stopping stirring, and aging for 12h; filtering after aging, washing the filter cake with deionized water until the filtrate is neutral, washing the filter cake with absolute ethyl alcohol with the volume 1 time of the filter cake for 1 time, and filtering to obtain the filter cake; then, the filter cake is dispersed by n-butanol-water solution with the volume of 1.5 times of that of the filter cake, and the volume ratio of n-butanol to deionized water is 1:0.2, heating to 110 ℃ and maintaining for 4 hours to obtain slurry; according to Ni 2+ /La 3+ The lanthanum nitrate is dissolved in ethanol-water solution to prepare salt solution S3 according to the mol ratio of 30, and the volume ratio of ethanol to water in the ethanol-water solution is 1:2, uniformly mixing the slurry with a salt solution S3 with the volume 1.5 times of that of the slurry, and evaporating to dryness at 90 ℃ by adopting a rotary evaporator to obtain a block; drying the obtained block at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Example 2
According to Ni 2+ /Mg 2+ The nickel nitrate and the magnesium nitrate are dissolved in 100mL of deionized water to prepare a salt solution S1 according to the molar ratio of 0.25, and Ni is used as the raw material 2+ /Al 3+ Sodium aluminate is dissolved in 200mL deionized water to prepare salt solution S2 with the molar ratio of 0.3; adding 300mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the PH of the precipitation reaction process to be 7-9; stirring for 1h after the dripping is finished, stopping stirring, and aging for 4h; filtering after aging, washing the filter cake with deionized water until the washing liquid is neutral, washing the filter cake with absolute ethyl alcohol 1 time the volume of the filter cake for 1 time, filteringObtaining a filter cake; then, the filter cake is dispersed by n-butanol-water solution with the volume of 1 time of the filter cake, and the volume ratio of the n-butanol to the deionized water is 1:0.01, heating to 80 ℃ and maintaining for 8 hours to obtain slurry; according to Ni 2+ /La 3+ The lanthanum nitrate is dissolved in ethanol-water solution to prepare salt solution S3 according to the mol ratio of 10, and the volume ratio of deionized ethanol and water in the ethanol-water solution is 1:3, uniformly mixing the slurry with a salt solution S3 with the volume 1.5 times of that of the slurry, and evaporating to dryness at 80 ℃ by adopting a rotary evaporator to obtain a block; drying the obtained block at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Example 3
According to Ni 2+ /Ca 2+ The molar ratio is 1, nickel nitrate and calcium nitrate are dissolved in 100mL deionized water to prepare salt solution S1, and Ni is used as the raw material 2+ /Al 3+ Sodium aluminate is dissolved in 200mL deionized water to prepare salt solution S2 with the molar ratio of 0.2; adding 600mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the PH of the precipitation reaction process to be 7-9; continuously stirring for 0.5h after the dripping is finished, stopping stirring, and aging for 24h; filtering after aging, washing the filter cake with deionized water until the washing liquid is neutral, washing the filter cake with absolute ethyl alcohol with the volume of 2 times of the filter cake for 1 time, and filtering to obtain the filter cake; then, the filter cake is dispersed by n-butanol-water solution with the volume of 1.5 times of the volume of the filter cake, and the volume ratio of the n-butanol to deionized water is 1:0.2, heating to 100 ℃ and maintaining for 4 hours to obtain slurry; according to Ni 2+ /Ce 4+ The cerium nitrate is dissolved in ethanol-water solution to prepare salt solution S3 in a molar ratio of 50, and the volume ratio of ethanol to deionized water in the ethanol-water solution is 1:1, uniformly mixing the slurry with a salt solution S3 with the volume of 2 times that of the slurry, and evaporating to dryness at 100 ℃ by adopting a rotary evaporator to obtain a block; drying the obtained block at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Example 4
According to Ni 2+ /Ba 2+ The molar ratio is 1, nickel nitrate and barium nitrate are dissolved in 100mL deionized water to prepare salt solution S1, and Ni is used as the raw material 2+ /Al 3+ Sodium aluminate was dissolved in 2 at a molar ratio of 0.2Preparing a salt solution S2 in 00mL of deionized water; adding 600mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the PH of the precipitation reaction process to be 7-9; continuously stirring for 0.5h after the dripping is finished, stopping stirring, and aging for 24h; filtering after aging, washing the filter cake with deionized water until the washing liquid is neutral, washing the filter cake with absolute ethyl alcohol with the volume of 2 times of the filter cake for 1 time, and filtering to obtain the filter cake; then, dispersing the filter cake by using n-butanol-water solution with the volume of 2 times of that of the filter cake, wherein the volume ratio of the n-butanol to the deionized water is 0.5, and heating to 120 ℃ for 2 hours to obtain slurry; according to Ni 2+ /Ce 4+ The cerium nitrate is dissolved in ethanol-water solution to prepare salt solution S3 in a molar ratio of 50, and the volume ratio of ethanol to deionized water in the ethanol-water solution is 1:1, uniformly mixing the slurry with a salt solution S3 with the volume of 2 times that of the slurry, and evaporating to dryness at 120 ℃ by adopting a rotary evaporator to obtain a block; drying the obtained block at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Example 5
According to Ni 2+ /Mg 2+ +Ba 2+ The molar ratio is 0.5 nickel nitrate, magnesium nitrate and barium nitrate are dissolved in 100mL deionized water to prepare salt solution S1 (wherein Mg 2+ 、Ba 2+ Molar ratio of 1:0.18), according to Ni 2+ /Al 3+ Sodium aluminate is dissolved in 200mL deionized water to prepare salt solution S2 with the molar ratio of 0.05; adding 450mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the PH of the precipitation reaction process to be 7-9; continuously stirring for 2 hours after the dripping is finished, stopping stirring, and aging for 4 hours; filtering after aging, washing the filter cake with deionized water until the washing liquid is neutral, washing the filter cake with absolute ethyl alcohol with the volume of 0.5 times of that of the filter cake for 1 time, and filtering to obtain the filter cake; then, the filter cake is dispersed by n-butanol-water solution with the volume of 1 time of the filter cake, and the volume ratio of the n-butanol to the deionized water is 1:0.2, heating to 100 ℃ and maintaining for 4 hours to obtain slurry; according to Ni 2+ /La 3+ The lanthanum nitrate is dissolved in ethanol-water solution to prepare salt solution S3 with the mol ratio of 30, and the volume of deionized ethanol and water in the ethanol-water solution is reducedThe ratio is 1:2, uniformly mixing the slurry with a salt solution S3 with the same volume as the slurry, and evaporating to dryness at 100 ℃ by adopting a rotary evaporator to obtain a block; drying the obtained block at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Example 6
According to Ni 2+ /Mg 2+ +Ca 2+ +Ba 2+ The molar ratio is 0.5 nickel nitrate, magnesium nitrate, calcium nitrate and barium nitrate are dissolved in 100mL deionized water to prepare salt solution S1 (wherein Mg 2+ 、Ca 2+ 、Ba 2+ In a molar ratio of 1:0.3:0.18), according to Ni 2+ /Al 3+ Sodium aluminate is dissolved in 200mL deionized water to prepare salt solution S2 with the molar ratio of 0.1; adding 450mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the PH of the precipitation process to be 7-9; stirring for 2 hours after the dripping is finished, stopping stirring, and aging for 12 hours; filtering after aging, washing the filter cake with deionized water until the washing liquid is neutral, washing the filter cake with absolute ethyl alcohol with the volume of 0.5 times of that of the filter cake for 1 time, and filtering to obtain the filter cake; then, dispersing the filter cake by using 1-time volume of n-butanol-water solution, wherein the volume ratio of n-butanol to deionized water is 1:0.2, heating to 120 ℃ and maintaining for 2 hours to obtain slurry; according to Ni 2+ /(La 3+ +Ce 4+ ) The molar ratio of lanthanum nitrate to cerium nitrate is 50 (wherein La 3+ /Ce 4+ 1:4) is dissolved in an ethanol-water solution to prepare a salt solution S3, wherein the volume ratio of ethanol to deionized water in the ethanol-water solution is 1:2, uniformly mixing the slurry with a salt solution S3 with the same volume as the slurry, and evaporating to dryness at 100 ℃ by adopting a rotary evaporator to obtain a block; drying the obtained block at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Comparative example 1
According to Ni 2+ /Al 3+ Sodium aluminate is dissolved in 200mL deionized water to prepare salt solution S2 with the molar ratio of 0.1; adding 450mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, adding a salt solution S2 into the reaction kettle for reaction, and maintaining the pH value of the kettle solution in the precipitation process to be 7-9; stirring continuously after the dripping is finished1h, then stopping stirring, and aging for 12h; filtering after aging, washing the filter cake with deionized water until the filtrate is neutral, washing the filter cake with absolute ethyl alcohol with the volume 1 time of the filter cake for 1 time, and filtering to obtain the filter cake; then, the filter cake is dispersed by n-butanol-water solution with the volume of 1.5 times of that of the filter cake, and the volume ratio of n-butanol to deionized water is 1:0.2, heating to 110 ℃ and maintaining for 4 hours to obtain slurry; according to Ni 2+ /La 3+ The lanthanum nitrate is dissolved in ethanol-water solution to prepare salt solution S3 according to the mol ratio of 30, and the volume ratio of ethanol to water in the ethanol-water solution is 1:2, uniformly mixing the slurry with a salt solution S3 with the volume 1.5 times of that of the slurry, and evaporating to dryness at 90 ℃ by adopting a rotary evaporator to obtain a block; drying the obtained block at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Comparative example 2
According to Ni 2+ /Mg 2+ Adding nickel nitrate and magnesium nitrate into 100mL deionized water according to the molar ratio of 0.5 to prepare a salt solution S1, and mixing according to Ni 2+ /Al 3+ Sodium aluminate is dissolved in 200mL deionized water to prepare salt solution S2 with the molar ratio of 0.1; adding 450mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the pH value of the kettle solution in the precipitation process to be 7-9; stirring for 1h after the dripping is finished, stopping stirring, and aging for 12h; filtering after aging, washing the filter cake with deionized water until the filtrate is neutral, washing the filter cake with absolute ethyl alcohol with the volume 1 time of the filter cake for 1 time, and filtering to obtain the filter cake; then, the filter cake is dispersed by n-butanol-water solution with the volume of 1.5 times of that of the filter cake, and the volume ratio of n-butanol to deionized water is 1:0.2, heating to 110 ℃ and maintaining for 4 hours to obtain slurry; drying the obtained slurry at 120 ℃ for 12h and roasting at 700 ℃ for 4h to obtain the catalyst for producing hydrogen by decomposing ammonia.
Comparative example 3
According to Ni 2+ /Al 3+ The molar ratio is 0.1, nickel nitrate and sodium aluminate are respectively dissolved in 100mL and 200mL deionized water to prepare salt solutions S1 and S2; adding 450mL of deionized water as a base solution into a reaction kettle, heating to 80 ℃, and then adding salt solutions S1 and S2 into the reaction kettle in parallel flow for reaction, and maintaining the pH value of the kettle solution in the precipitation process to be 7-9; dripping inContinuing stirring for 1h after finishing, stopping stirring, and aging for 12h; filtering after aging, washing the filter cake with deionized water until the filtrate is neutral, washing the filter cake with absolute ethyl alcohol with the volume 1 time of the filter cake for 1 time, and filtering to obtain the filter cake; then, the filter cake is dispersed by n-butanol-water solution with the volume of 1.5 times of that of the filter cake, and the volume ratio of n-butanol to deionized water is 1:0.2, heating to 110 ℃ and maintaining for 4 hours to obtain slurry; drying the obtained slurry at 120 ℃ for 12 hours, and roasting at 700 ℃ for 4 hours to obtain the catalyst for producing hydrogen by decomposing ammonia.
The catalysts for producing hydrogen by decomposing ammonia prepared in examples 1 to 6 and comparative examples 1 to 3 were used for the reaction of producing hydrogen by decomposing ammonia: the catalysts (0.1 g,40-60 mesh) of each example and comparative example were taken separately from analytically pure alpha-Al 2 O 3 (0.9 g,40-60 mesh) and mixed well with 50% H 2 /N 2 Atmosphere (120 mL/min), pre-reducing at 700 ℃ for 1h. After completion of the reduction, at 50% H 2 /N 2 The reaction temperature is reduced to 550 ℃ under the atmosphere, and after the temperature is reduced to 550 ℃, the reaction is switched to NH 3 (molar ratio 1:1, ghsv=6000 mL/g) -cat H) carrying out an ammonolysis reaction. After the reacted gas was cooled, it was analyzed on line using a Shimadzu GC-2014 gas chromatograph.
After 300h of continuous operation, NH under the action of the catalysts of the examples and comparative examples was tested 3 The decomposition conversion and hydrogen production rate were as shown in Table 1 and FIG. 1.
TABLE 1
From the data in Table 1, examples 1 to 6 and comparative examples 1 to 3: the catalysts of examples 1 to 6 were NH after 300h of continuous operation 3 The decomposition conversion rate is still above 95%, and the hydrogen production rate is also 6.35 mmol/g -cat -1 *min -1 Above.
Comparative example 1 preparation without alkaline earth metal added, NH after 300 hours of continuous operation under the action of the alkaline earth metal 3 The decomposition conversion rate is reduced to 90.65%, and the hydrogen production rate is reduced to 6.07 mmol/g -cat -1 *min -1 。
Comparative example 2 preparation without addition of lanthanide metals, NH after 300h of continuous operation under the action of the lanthanide metals 3 The decomposition conversion rate is obviously reduced to 84.79 percent, and the hydrogen production rate is reduced to 5.68mmol x g -cat -1 *min -1 。
NH after 100h of operation under the action of the catalyst of comparative example 3 3 The decomposition conversion rate was 86.48%, the hydrogen production rate was 5.79 mmol/(g) -cat * min); after 300h of continuous operation, NH 3 The decomposition conversion was 78.17%, and the hydrogen production rate was 5.23 mmol/(g) -cat * min). It can be seen that comparative example 3, although having a comparable particle size to example 1, was run for NH after 100h to 300h 3 The decomposition conversion was reduced from 86.48% to 78.17%, the activity was far lower than in example 1 and unstable. This is because the catalyst surface acidity and alkalinity cannot be effectively adjusted without adding alkaline earth metal in the synthesis process of comparative example 3, so that the initial activity is lower than that of the catalyst of example 1; in addition, lanthanide metals were not added during the synthesis of comparative example 3, and the active metal-carrier interaction force was weak, resulting in instability.
In conclusion, the catalyst for preparing hydrogen by ammonia decomposition has the advantages of narrow particle size distribution, high catalyst activity, stable performance, mild preparation conditions and large-scale preparation and application prospects. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (9)
1. The catalyst for producing hydrogen by ammonia decomposition is characterized by comprising an active metal component, an alkaline earth metal component, a lanthanide metal component and an auxiliary agent, wherein a precursor of the active metal component is nickel salt, a precursor of the alkaline earth metal component is alkaline earth metal salt, a precursor of the lanthanide metal component is lanthanide metal salt, and a precursor of the auxiliary agent is meta-aluminate;
the preparation method of the catalyst for producing hydrogen by ammonia decomposition comprises the following steps:
1) After heating the base solution, adding a salt solution S1 comprising nickel salt and alkaline earth metal salt and a salt solution S2 comprising meta-aluminate into the base solution in parallel flow, reacting and aging; wherein, when the salt solution S1 and the salt solution S2 are added in parallel and in the aging process, the pH of the base solution is controlled to be 7-9;
2) Filtering and washing the aged product in the step 1) to obtain a filter cake;
3) Dispersing the filter cake obtained in the step 2) in a dispersing agent, and heating to obtain slurry; wherein the dispersing agent is n-butanol-water solution; the volume ratio of the n-butanol to the water in the n-butanol-water solution is 1 (0.01-0.5);
4) Mixing a salt solution S3 containing lanthanide metal salt with the slurry obtained in the step 3), drying and roasting to obtain an ammonia decomposition hydrogen production catalyst; the solvent of the salt solution S3 is ethanol-water, and the volume ratio of the ethanol to the water is 1:1-3; the drying specifically comprises the following steps: and (3) carrying out rotary steaming on the mixed materials to obtain blocks, and drying the blocks at 100-130 ℃ for 8-24 hours.
2. The catalyst for producing hydrogen by decomposing ammonia according to claim 1, wherein the nickel salt is nickel nitrate;
and/or, the meta-aluminate is sodium meta-aluminate;
and/or the alkaline earth metal salt is one or more of magnesium nitrate, calcium nitrate and barium nitrate;
and/or the lanthanide metal salt is one or two of lanthanum nitrate and cerium nitrate;
and/or the molar ratio of nickel to aluminum in the catalyst is 0.05-0.3; the molar ratio of nickel to alkaline earth metal is 0.25-1; the molar ratio of nickel/lanthanide metal is 10-50.
3. A method for preparing the catalyst for producing hydrogen by decomposing ammonia according to any one of claims 1 to 2, comprising the steps of:
1) After heating the base solution, adding a salt solution S1 comprising nickel salt and alkaline earth metal salt and a salt solution S2 comprising meta-aluminate into the base solution in parallel flow, reacting and aging; wherein, when the salt solution S1 and the salt solution S2 are added in parallel and in the aging process, the pH of the base solution is controlled to be 7-9;
2) Filtering and washing the aged product in the step 1) to obtain a filter cake;
3) Dispersing the filter cake obtained in the step 2) in a dispersing agent, and heating to obtain slurry; wherein the dispersing agent is n-butanol-water solution; the volume ratio of the n-butanol to the water in the n-butanol-water solution is 1 (0.01-0.5);
4) Mixing a salt solution S3 containing lanthanide metal salt with the slurry obtained in the step 3), drying and roasting to obtain an ammonia decomposition hydrogen production catalyst; the solvent of the salt solution S3 is ethanol-water, and the volume ratio of the ethanol to the water is 1:1-3; the drying specifically comprises the following steps: and (3) carrying out rotary steaming on the mixed materials to obtain blocks, and drying the blocks at 100-130 ℃ for 8-24 hours.
4. A method of preparing an ammonia destruction hydrogen production catalyst according to claim 3, wherein in step 1), one or more of the following features are further included:
a1, the solvent of the salt solution S1 is deionized water;
a2, the solvent of the salt solution S2 is deionized water;
a3, the base solution is deionized water;
a4, heating the base solution to 70-90 ℃;
a5, the volume ratio of the total volume of the salt solutions S1 and S2 to the volume of the base solution is 1:1-2;
a6, the reaction is carried out in a reaction kettle;
a7, aging time is 4-24 hours.
5. A method for preparing a catalyst for producing hydrogen by decomposing ammonia as claimed in claim 3, wherein in step 2), the washing is to wash the filter cake with deionized water until the filtrate becomes neutral, and then wash the filter cake once again with absolute ethanol.
6. The method for producing a catalyst for producing hydrogen by decomposing ammonia as claimed in claim 5, wherein the volume ratio of said absolute ethanol to said filter cake is (0.5-2): 1.
7. A method of preparing an ammonia destruction hydrogen production catalyst according to claim 3, wherein in step 3), one or more of the following features are further included:
b1, the volume ratio of the dispersing agent to the filter cake is (1-2) 1;
b2, the heating temperature is 80-120 ℃;
b3, heating for 2-8 hours.
8. A method of preparing an ammonia destruction hydrogen production catalyst according to claim 3, characterized in that in step 4), one or more of the following features are included:
c1, the volume ratio of the salt solution S3 to the slurry is 1-2:1;
c2, the roasting temperature is 600-800 ℃;
and c3, roasting for 2-8 hours.
9. Use of the catalyst for producing hydrogen by ammonia decomposition according to any one of claims 1 to 2 in a reaction for producing hydrogen by ammonia decomposition, characterized in that the catalyst for producing hydrogen by ammonia decomposition is used in H before the reaction for producing hydrogen by ammonia decomposition 2 /N 2 Pre-reducing for 1-3 hours at 600-800 ℃ in the atmosphere.
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