CN114643063A - Catalyst preparation method and carbon nanotube preparation method, and catalyst and carbon nanotube prepared thereby - Google Patents
Catalyst preparation method and carbon nanotube preparation method, and catalyst and carbon nanotube prepared thereby Download PDFInfo
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 94
- 239000003054 catalyst Substances 0.000 title claims abstract description 89
- 239000002041 carbon nanotube Substances 0.000 title claims abstract description 83
- 229910021393 carbon nanotube Inorganic materials 0.000 title claims abstract description 83
- 238000002360 preparation method Methods 0.000 title claims abstract description 20
- 238000006243 chemical reaction Methods 0.000 claims abstract description 58
- 239000000463 material Substances 0.000 claims abstract description 48
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 45
- 239000012266 salt solution Substances 0.000 claims abstract description 41
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000003513 alkali Substances 0.000 claims abstract description 37
- 239000008367 deionised water Substances 0.000 claims abstract description 32
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 32
- 238000000034 method Methods 0.000 claims abstract description 31
- YIXJRHPUWRPCBB-UHFFFAOYSA-N magnesium nitrate Chemical compound [Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O YIXJRHPUWRPCBB-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000003756 stirring Methods 0.000 claims abstract description 22
- 239000007788 liquid Substances 0.000 claims abstract description 18
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 15
- 238000011049 filling Methods 0.000 claims abstract description 14
- 238000005245 sintering Methods 0.000 claims abstract description 14
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims abstract description 13
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims abstract description 13
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 claims abstract description 12
- MFUVDXOKPBAHMC-UHFFFAOYSA-N magnesium;dinitrate;hexahydrate Chemical compound O.O.O.O.O.O.[Mg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MFUVDXOKPBAHMC-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000012216 screening Methods 0.000 claims abstract description 11
- XNDZQQSKSQTQQD-UHFFFAOYSA-N 3-methylcyclohex-2-en-1-ol Chemical compound CC1=CC(O)CCC1 XNDZQQSKSQTQQD-UHFFFAOYSA-N 0.000 claims abstract description 6
- 239000002245 particle Substances 0.000 claims abstract description 6
- QGUAJWGNOXCYJF-UHFFFAOYSA-N cobalt dinitrate hexahydrate Chemical compound O.O.O.O.O.O.[Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O QGUAJWGNOXCYJF-UHFFFAOYSA-N 0.000 claims abstract description 5
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 18
- 239000001257 hydrogen Substances 0.000 claims description 13
- 229910052739 hydrogen Inorganic materials 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 11
- 239000007789 gas Substances 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 239000000243 solution Substances 0.000 description 18
- 239000006185 dispersion Substances 0.000 description 13
- 230000002572 peristaltic effect Effects 0.000 description 7
- 238000001878 scanning electron micrograph Methods 0.000 description 7
- 239000012267 brine Substances 0.000 description 6
- 238000000975 co-precipitation Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 6
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 6
- 239000002244 precipitate Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 229910021645 metal ion Inorganic materials 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 238000005303 weighing Methods 0.000 description 4
- 229910002651 NO3 Inorganic materials 0.000 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 150000001868 cobalt Chemical class 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 238000000227 grinding Methods 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 159000000003 magnesium salts Chemical class 0.000 description 2
- 150000002696 manganese Chemical class 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000011572 manganese Substances 0.000 description 2
- 239000002071 nanotube Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 2
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- IVMYJDGYRUAWML-UHFFFAOYSA-N cobalt(ii) oxide Chemical class [Co]=O IVMYJDGYRUAWML-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000011231 conductive filler Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 230000037361 pathway Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000000527 sonication Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J23/889—Manganese, technetium or rhenium
- B01J23/8892—Manganese
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/40—Catalysts, in general, characterised by their form or physical properties characterised by dimensions, e.g. grain size
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/15—Nano-sized carbon materials
- C01B32/158—Carbon nanotubes
- C01B32/16—Preparation
- C01B32/162—Preparation characterised by catalysts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B2202/00—Structure or properties of carbon nanotubes
- C01B2202/20—Nanotubes characterized by their properties
- C01B2202/36—Diameter
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Nanotechnology (AREA)
- Inorganic Chemistry (AREA)
- Catalysts (AREA)
Abstract
The invention provides a preparation method, which comprises the following steps: preparing a salt solution from magnesium nitrate, aluminum nitrate, manganese nitrate, cobalt nitrate and deionized water, wherein the mass ratio of the magnesium nitrate, the aluminum nitrate, the manganese nitrate and the cobalt nitrate is (5.86-6.56): (7.225-7.295): (19.82-20.03): (23.42-23.66) calculated according to magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, manganese nitrate and cobalt nitrate hexahydrate; preparing alkali liquor from sodium hydroxide and deionized water; continuously filling salt solution and alkali liquor into a reaction kettle set at 30-40 ℃; stopping filling the salt solution, and continuing filling the alkali liquor until the pH value is 10.36-10.44; stirring the contents of the reaction kettle to carry out reaction; removing liquid in the reaction kettle to obtain a material cake; drying the material cake, and sintering at 390-410 ℃ to obtain a dry material; and screening the dry materials, and taking particles of 60-80 meshes to obtain the catalyst. The preparation method of the invention can prepare the catalyst suitable for preparing high-quality carbon nano tubes. The invention also provides a method for preparing the carbon nano tube, a catalyst and the carbon nano tube.
Description
Technical Field
The invention relates to the field of carbon nanotube preparation, in particular to a catalyst preparation method and a carbon nanotube preparation method, and a catalyst and a carbon nanotube prepared by the catalyst.
Background
Carbon nanotubes, as an emerging material, have been increasingly used for various technical developments and practical applications.
The preparation of carbon nanotubes usually requires the use of a catalyst. Chinese patent application CN104084214A proposes a method for preparing a catalyst for carbon nanotube, wherein a solution containing soluble magnesium salt, soluble aluminum salt, soluble manganese salt and soluble cobalt salt is mixed with an alkaline solution, pH is controlled to 2-12, a precipitate is obtained by coprecipitation and calcined to obtain the catalyst, wherein the mass ratio of the soluble magnesium salt, the soluble aluminum salt, the soluble manganese salt and the soluble cobalt salt is 1.25-20.96: 1.34-30.55: 2.75-50.87: 1.56-60.36. The carbon nano tube prepared by the method has the tube diameter of 10-30nm and has excellent dispersion performance and conductivity. Compared with other catalyst preparation methods such as an ion exchange method, the coprecipitation method has the advantages of simple process and the like.
The diameter of the carbon nanotube is one of the important parameters of the carbon nanotube. Generally, the thinner the tube diameter of the carbon nanotube is, the more the tube number of the carbon nanotube of the same quality is, and further the more chance of mutual contact when it is added as a conductive filler to a conductive mesh chain formed in a paint, the more conductive paths are formed, so that the paint conductivity is better.
The dispersion property is also one of the important properties of carbon nanotubes. Generally, the carbon nanotubes are prepared in an agglomerated state, and in order to disperse them into each other, means such as sonication or milling is used. The carbon nano tube with good dispersion performance needs short dispersion time and low dispersion difficulty; the carbon nano tube with poor dispersion property needs long dispersion time and high dispersion difficulty. Carbon nanotubes, which are well dispersed in the coating, also contribute to increased coating conductivity because more conductive pathways are formed. However, generally, as the diameter of the carbon nanotube is smaller, the carbon nanotube is more likely to be curled and aggregated, thereby affecting the dispersibility thereof.
There is still a need for improvement of the catalyst in order to obtain carbon nanotubes having small tube diameter and still having good dispersibility.
Disclosure of Invention
In one aspect, the present invention provides a method for preparing a catalyst, characterized in that the method comprises the steps of:
preparing a salt solution from magnesium nitrate, aluminum nitrate, manganese nitrate, cobalt nitrate and deionized water, wherein the mass ratio of the magnesium nitrate, the aluminum nitrate, the manganese nitrate and the cobalt nitrate is (5.86-6.56) to (7.225-7.295) to (19.82-20.03) to (23.42-23.66) in terms of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, manganese nitrate and cobalt nitrate hexahydrate;
preparing alkali liquor from sodium hydroxide and deionized water;
continuously filling the salt solution and the alkali liquor into a reaction kettle set at 30-40 ℃;
stopping filling the salt solution, and continuing to fill the alkali liquor until the pH value is 10.36-10.44;
stirring the contents of the reaction kettle to carry out reaction;
removing liquid in the reaction kettle to obtain a material cake;
drying the material cake, and sintering at 390-410 ℃ to obtain a dry material; and
and screening the dry material, and taking particles of 60-80 meshes to obtain the catalyst.
Preferably, the pH is 10.4.
Preferably, the stirring is continued for 30 to 60 minutes.
Preferably, the cake is obtained by centrifugal drying.
Preferably, the sintering is performed for 3 to 6 hours.
Preferably, deionized water is charged into the reaction kettle before the salt solution and the alkali solution are charged into the reaction kettle.
In another aspect, the present invention provides a catalyst prepared by the above catalyst preparation method.
In another aspect, the present invention provides a method for preparing a carbon nanotube, comprising:
introducing a hydrogen-containing carbon source gas into the reaction container provided with the catalyst,
decomposing the hydrogen-containing carbon source gas in the reaction vessel to produce hydrogen gas,
the catalyst is reduced by the hydrogen gas, and the reduced catalyst catalyzes the hydrogen-containing carbon source gas to form carbon nanotubes.
In another aspect, the present invention provides a carbon nanotube prepared by the method for preparing a carbon nanotube as described above, wherein a part of the carbon nanotube has a tube diameter of less than 10 nm.
Preferably, the tube diameters of all the carbon nanotubes are in the range of 5-15 nm.
Drawings
FIG. 1 is a scanning electron micrograph of carbon nanotubes prepared with a catalyst according to an embodiment of the present invention
Fig. 2 is a scanning electron micrograph of carbon nanotubes prepared by the catalyst according to an embodiment of the present invention.
Fig. 3 is a scanning electron micrograph of carbon nanotubes prepared with a catalyst according to an embodiment of the present invention.
Fig. 4 is a scanning electron micrograph of carbon nanotubes prepared with a catalyst according to an embodiment of the present invention.
Fig. 5 is a scanning electron micrograph of carbon nanotubes prepared with a catalyst according to an embodiment of the present invention.
Fig. 6 is a scanning electron micrograph of carbon nanotubes prepared with a catalyst according to an embodiment of the present invention.
Detailed Description
The invention provides a preparation method of a catalyst containing alumina, and the prepared catalyst can be used for preparing carbon nanotubes with small tube diameter and still good dispersibility.
The preparation method comprises the following steps:
preparing a salt solution from magnesium nitrate, aluminum nitrate, manganese nitrate, cobalt nitrate and deionized water, wherein the mass ratio of the magnesium nitrate, the aluminum nitrate, the manganese nitrate and the cobalt nitrate is (5.86-6.56): (7.225-7.295): (19.82-20.03): (23.42-23.66) calculated according to magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, manganese nitrate and cobalt nitrate hexahydrate;
preparing alkali liquor from sodium hydroxide and deionized water;
continuously filling the salt solution and the alkali liquor into a reaction kettle set at 30-40 ℃;
stopping filling the salt solution, and continuing to fill the alkali liquor until the pH value is 10.36-10.44;
stirring the contents of the reaction kettle to carry out reaction;
removing liquid in the reaction kettle to obtain a material cake;
drying the material cake, and sintering at 390-410 ℃ to obtain a dry material; and
and screening the dry material, and taking particles of 60-80 meshes to obtain the catalyst.
The invention also relates to a method for preparing the catalyst for preparing the carbon nano tube by a coprecipitation method. The method comprises the steps of reacting nitrate solution of aluminum, magnesium, manganese and cobalt with sodium hydroxide and coprecipitating to generate coprecipitated hydroxide, and then sintering the coprecipitated hydroxide to obtain the catalyst containing alumina and magnesium, manganese and cobalt oxides serving as active substances and loaded on the alumina.
Without being bound to any theory, it has been surprisingly found that when prepared with a specific combination of raw materials and process parameters, a catalyst can be obtained and with this catalyst carbon nanotubes can be prepared having small tube diameters and still having good dispersibility. Such carbon nanotubes can achieve better conductivity in applications such as conductive coatings.
When the salt solution is prepared, the mass ratio of magnesium nitrate, aluminum nitrate, manganese nitrate and cobalt nitrate is selected to be within the range of (5.86-6.56) to (7.225-7.295) to (19.82-20.03) to (23.42-23.66) according to the mass ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, manganese nitrate and cobalt nitrate. For example, a salt solution may be prepared using 6.21. + -. 0.35kg of magnesium nitrate, 7.26. + -. 0.035kg of aluminum nitrate, 39.85. + -. 0.21kg of manganese nitrate solution (50% purity), and 23.54. + -. 0.12kg of cobalt nitrate. The salt solution contains deionized water as a solvent. For better dissolution, water may be added in portions. Preferably, an appropriate amount of water is added to the dissolution tank first, followed by addition of salt to the water and then addition of a portion of the water. Dissolution of the salt may be facilitated by appropriate stirring.
The alkali liquor in the invention is sodium hydroxide solution. The concentration of sodium hydroxide can be appropriately selected. The lye of the desired concentration can be obtained by diluting the concentrated lye with deionized water.
Continuously filling the prepared salt solution and alkali liquor into the reaction kettle simultaneously. The invention does not adopt a feeding mode of firstly filling one solution and then slowly adding the other solution, but continuously filling the salt solution and the alkali solution simultaneously. Without being bound by any theory, such feeding is advantageous to obtain a catalyst morphology capable of producing carbon nanotubes of small tube diameter and excellent dispersion.
And simultaneously continuously filling the salt solution and the alkali solution by respectively and continuously introducing the salt solution and the alkali solution into the reaction kettle at certain flow rates. The feed rate may be controlled, for example, by a peristaltic pump. In the invention, the salt solution and the alkali liquor are continuously filled at the same time, so that the salt solution and the alkali liquor which are filled firstly can start to react firstly. The salt solution and the alkali solution which are filled later are mixed and continue to react under the condition that the salt-alkali reaction product exists in the solution. Also, the concentration of nitrate metal ions in the solution is not significantly excessive during this process. Without being bound by any theory, these factors may affect the growth structure of the multicomponent crystals in the obtained reaction product hydroxide, and further affect the morphology of the catalyst obtained after subsequent sintering, and finally affect the morphology of the carbon nanotubes prepared and grown by using the catalyst.
In the method of the invention, the reaction kettle is always kept at the temperature of 30-40 ℃ in the feeding and reaction stages. The temperature of the reaction kettle can be kept by opening the jacket to circulate water.
The salt solution and the alkali liquor can be filled with the salt solution and the alkali liquor while being assisted with proper stirring.
And stopping filling the salt solution when enough salt solution for preparing the catalyst exists in the reaction kettle. Continuously charging the alkali liquor until the pH value reaches 10.36-10.44, and then stopping adding the alkali liquor. Continued charging with lye and bringing the pH to the above-mentioned range ensures complete reaction in the end. Without being bound to any theory, this pH range may be beneficial to obtain the desired catalyst morphology.
Then, the materials were kept uniformly mixed by stirring and reacted. The coprecipitation reaction will produce a precipitate that is insoluble in water.
After the reaction is carried out for a sufficient time, the reaction is stopped, and the liquid in the reaction kettle is removed to obtain a cake. The solid-liquid separation can be carried out by a suitable method, for example, by filtration or centrifugal drying. The centrifugal method is preferable because of its high efficiency. The cake may be washed. The washing with deionized water may be performed during the spin-drying.
And then, drying the material cake and sintering to obtain a dry material. In the present invention, the sintering temperature is selected to be 390-410 ℃.
After sintering, screening the dry material, and taking 60-80 mesh particles to obtain the catalyst of the invention.
As described below, the method of the present invention obtains a catalyst by co-precipitation by selecting the nitrate ratio, reaction temperature, pH value, sintering temperature, product particle size, and continuously charging salt solution and alkali solution at the same time. All these parameters act synergistically to obtain a catalyst with a particular catalytic capacity. As described below, the catalyst prepared by the method of the present invention can be used to prepare carbon nanotubes having a small tube diameter and still having good dispersibility. The catalyst of the present invention can prepare carbon nanotube with pipe diameter of 5-15nm and disperse carbon nanotube fully in short dispersing time.
In a preferred embodiment, the pH is adjusted to 10.4.
In a preferred embodiment, stirring is continued for 30 to 60 minutes. The salt solution and the alkali liquor are charged and reacted at the same time, so the reaction is full, and the reaction time after the charging is finished can be shorter.
In a preferred embodiment, the sintering is carried out for 3 to 6 hours. More preferably, sintering is carried out for 4 hours.
In a preferred embodiment, the reaction kettle is filled with deionized water before the salt solution and the alkali solution are filled into the reaction kettle. Thus, the coprecipitation reaction at lower ion concentration can be realized by taking concentrated salt solution and alkali liquor as feed materials.
The invention also provides a catalyst prepared by the catalyst preparation method. The catalyst thus prepared can prepare carbon nanotubes of small diameter and excellent dispersion.
The invention also provides a preparation method of the carbon nano tube, which comprises the following steps: a hydrogen-containing carbon source gas is introduced into a reaction vessel in which the catalyst of the present invention is disposed, the hydrogen-containing carbon source gas is decomposed in the reaction vessel to generate hydrogen gas, the catalyst is reduced by the hydrogen gas, and the reduced catalyst catalyzes the hydrogen-containing carbon source gas to form carbon nanotubes. The preparation method of the carbon nano tube uses the catalyst of the invention, and directly adopts hydrogen decomposed by the hydrogen-containing carbon source to reduce the catalyst, rather than using the hydrogen alone to reduce the catalyst in advance. The preparation method of the carbon nano tube can be matched with the catalyst of the invention to prepare the carbon nano tube with small tube diameter and excellent dispersion. Preferred hydrogen-containing carbon source gases include propylene, ethane or acetylene, among others.
The invention also provides the carbon nano tube prepared by the preparation method of the carbon nano tube. The diameter of a part of the carbon nanotubes is less than 10 nm. By using the catalyst of the present invention, carbon nanotubes with small tube diameters are produced. In a preferred embodiment, all of the carbon nanotubes have a tube diameter in the range of 5 to 15 nm. That is, the carbon nanotubes prepared by using the catalyst of the present invention may be a collection of carbon nanotubes having a generally small tube diameter.
The scheme of the invention is further illustrated by the following examples.
Catalyst example 1
The catalyst was prepared by performing the following steps.
75kg of deionized water is added into the A dissolving kettle, 5.86kg of magnesium nitrate hexahydrate, 7.225kg of aluminum nitrate nonahydrate, 39.64kg of manganese nitrate solution (with the purity of 50 percent) and 23.42kg of cobalt nitrate hexahydrate are weighed respectively, 26.88kg of deionized water is added, and stirring is carried out (at the speed of 50RPM) until the materials are completely dissolved, so as to obtain salt solution.
And weighing 72.58kg of liquid alkali (with the concentration of 32%) in the B dissolving kettle, weighing 28.35kg of deionized water, and stirring to completely mix the materials to obtain the alkali liquor.
After the reaction kettle is cleaned, 25kg of deionized water is weighed and put into the reaction kettle, the temperature of the reaction kettle is set to be 35 ℃, and the kettle is opened to conduct water circulation heating.
The peristaltic pump for feeding was calibrated. The salt solution and the lye were then fed simultaneously into the reaction kettle using a peristaltic pump while stirring. The salt solution was fed at a rate of 10.19L/h and the lye at a rate of 3.9L/h. The brine was stopped when the amount of hydroxide precipitate, calculated as the amount of metal ions in the brine feed, reached about 20 kg. The addition of lye was continued until the pH was 10.4.
After the reaction kettle is continuously stirred for half an hour, the stirring is closed. And (3) spin-drying the feed liquid by using a centrifugal machine to obtain a material cake, and washing the material cake for three times by using deionized water according to the ratio of the deionized water to the feed liquid of 1: 3 in the process of spin-drying the feed liquid.
The material cake is dried for 12 hours at 110 ℃ and then sintered for 4 hours at 400 ℃ to obtain a dry material. And (3) screening the dry materials, wherein the screening interval is 60-80 meshes of screen meshes, so as to obtain a catalyst sample 1.
Catalyst example 2
The catalyst was prepared by performing the following steps.
75kg of deionized water is added into the A dissolving kettle, 6.21kg of magnesium nitrate, 7.26kg of aluminum nitrate, 39.85kg of manganese nitrate solution (with the purity of 50 percent) and 23.54kg of cobalt nitrate are weighed respectively, 27kg of deionized water is added, and stirring is started (at the speed of 50RPM) until the materials are completely dissolved, so that salt solution is obtained.
And weighing 72.93kg of liquid alkali (with the concentration of 32%) in the B dissolving kettle, weighing 28.5kg of deionized water, and stirring to completely mix the materials to obtain the alkali liquor.
After the reaction kettle is cleaned, 25kg of deionized water is weighed and put into the reaction kettle, the temperature of the reaction kettle is set to be 35 ℃, and the kettle is opened to conduct water circulation heating.
The peristaltic pump for feeding was calibrated. The salt solution and the lye were then fed simultaneously into the reaction kettle using a peristaltic pump while stirring. The salt solution was fed at a rate of 10.19L/h and the lye at a rate of 3.9L/h. The brine was stopped when the amount of hydroxide precipitate, calculated as the amount of metal ions in the brine feed, reached about 20 kg. The addition of lye was continued until the pH was 10.4.
After the reaction kettle is continuously stirred for half an hour, the stirring is closed. And (3) spin-drying the feed liquid by using a centrifugal machine to obtain a material cake, and washing the material cake for three times by using deionized water according to the ratio of the deionized water to the feed liquid of 1: 3 in the process of spin-drying the feed liquid.
The material cake is dried for 12 hours at 110 ℃ and then sintered for 4 hours at 400 ℃ to obtain a dry material. And screening the dry materials by a screen with the screening interval of 60-80 meshes so as to obtain a catalyst sample 2.
Catalyst example 3
The catalyst was prepared by performing the following steps.
75kg of deionized water is added into the A dissolving kettle, 6.56kg of magnesium nitrate, 7.295kg of aluminum nitrate, 40.06kg of manganese nitrate solution (with the purity of 50 percent) and 23.66kg of cobalt nitrate are weighed respectively, 27kg of deionized water is added, and stirring is carried out (at the speed of 50RPM) until the materials are completely dissolved, so as to obtain salt solution.
73.28kg of liquid alkali (with the concentration of 32%) is weighed into the B dissolving kettle, 28.65kg of deionized water is weighed into the B dissolving kettle, and stirring is started to completely mix the materials to obtain the alkali liquor.
After the reaction kettle is cleaned, 25kg of deionized water is weighed and put into the reaction kettle, the temperature of the reaction kettle is set to be 35 ℃, and the kettle is opened to carry out water circulation heating.
The peristaltic pump for feeding was calibrated. The salt solution and the lye were then fed simultaneously into the reaction kettle using a peristaltic pump while stirring. The salt solution was fed at a rate of 10.19L/h and the lye at a rate of 3.9L/h. The brine was stopped when the amount of hydroxide precipitate, calculated as the amount of metal ions in the brine feed, reached about 20 kg. The addition of lye was continued until the pH was 10.4.
After the reaction kettle is continuously stirred for half an hour, the stirring is closed. And (3) spin-drying the feed liquid by using a centrifugal machine to obtain a material cake, and washing the material cake for three times by using deionized water according to the ratio of the deionized water to the feed liquid of 1: 3 in the process of spin-drying the feed liquid.
The material cake is dried for 12 hours at 110 ℃ and then sintered for 4 hours at 400 ℃ to obtain a dry material. And (4) screening the dry materials, wherein the screening interval is 60-80 meshes of screen meshes, so as to obtain a catalyst sample 3.
Example of production of carbon nanotube
Carbon nanotubes were prepared using the catalysts prepared in catalyst examples 1, 2, and 3, respectively, using the following procedure:
1. introducing nitrogen into the fluidized bed and heating to 660-680 ℃;
2. 1g of catalyst was added;
3. propylene was fed at a flow rate of 1L/min, and nitrogen was fed at a flow rate of 1L/min to conduct the reaction for 60 min.
And performing electron microscopic characterization on the prepared carbon nano tube. Fig. 1-6 show scanning electron micrographs of carbon nanotubes produced using catalyst samples 1-3, where fig. 1-2 are catalyst sample 1, fig. 3-4 are catalyst sample 2, and fig. 5-6 are catalyst sample 3. The tube diameters of the nanotubes produced were found to be no more than 15nm and could be mostly below 10nm, and as low as about 5 nm. The diameter range of the carbon nano tube is obviously less than that of the carbon nano tube with the tube diameter range of 10-30nm prepared by the catalyst of CN 104084214A.
It can be seen from the electron micrograph that the obtained carbon nanotubes have few defects, uniform tube diameter and good dispersibility, and most of the carbon nanotubes do not have severe curling.
The prepared nanotubes are dispersed by grinding with a grinder, and the dispersion time is only 10h to obtain sufficient dispersion. Dispersibility can be examined by the standing viscosity after premixing the carbon nanotubes with N-methylpyrrolidone (NMP) and a dispersant at a solid content of about 5% and grinding to make a slurry. The 7-day static viscosity of the carbon nanotubes prepared in catalyst examples 1 to 3 was about 7600cps, and the 10-day static viscosity was about 6400cps, indicating that the small-diameter carbon nanotubes of the present invention can be stably dispersed.
An electrode material was formulated using the carbon nanotubes prepared in catalyst example 2. The slurry is composed of carbon nanotubes as a conductive agent, a main material and a binder. The main material is ternary lithium material, and the binder is PADF. The ratio of the main material to the adhesive to the conductive agent is 97.8: 1.2: 1. The electrode material thus obtained had a viscosity of 985Pa/s and an average resistivity of 5.12. omega. cm. The electrode material is prepared by adopting three commercially available carbon nanotubes according to the same formula, the viscosity is 6828 Pa/s, the viscosity is 7800 Pa/s, the 9600Pa/s, and the resistivity mean value is 10.87 omega cm, 11.2 omega cm and 9.66 omega cm. This shows that the carbon nanotubes of the present invention have high dispersibility and can produce a composite material having high electrical conductivity. As described above, the catalyst prepared by the co-deposition method of the present invention can be used to prepare carbon nanotubes having a small tube diameter and still having good dispersibility.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (10)
1. A method for preparing a catalyst, comprising the steps of:
preparing a salt solution from magnesium nitrate, aluminum nitrate, manganese nitrate, cobalt nitrate and deionized water, wherein the mass ratio of the magnesium nitrate, the aluminum nitrate, the manganese nitrate and the cobalt nitrate is (5.86-6.56): (7.225-7.295): (19.82-20.03): (23.42-23.66) calculated according to magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, manganese nitrate and cobalt nitrate hexahydrate;
preparing alkali liquor from sodium hydroxide and deionized water;
continuously filling the salt solution and the alkali liquor into a reaction kettle set at 30-40 ℃;
stopping filling the salt solution, and continuing to fill the alkali liquor until the pH value is 10.36-10.44;
stirring the contents of the reaction kettle to carry out reaction;
removing liquid in the reaction kettle to obtain a material cake;
drying the material cake, and sintering at 390-410 ℃ to obtain a dry material; and
and screening the dry material, and taking particles of 60-80 meshes to obtain the catalyst.
2. The method for preparing a catalyst according to claim 1,
the pH was 10.4.
3. The method for preparing a catalyst according to claim 1,
the stirring is continued for 30-60 minutes.
4. The method for preparing a catalyst according to claim 1,
and centrifugally drying to obtain the material cake.
5. The method for preparing a catalyst according to claim 1,
the sintering is carried out for 3-6 hours.
6. The method for preparing a catalyst according to claim 1,
and before the salt solution and the alkali liquor are filled into the reaction kettle, deionized water is filled into the reaction kettle.
7. A catalyst prepared by the catalyst preparation method of any one of claims 1-6.
8. A method for producing carbon nanotubes, the method comprising:
introducing a hydrogen-containing carbon source gas into a reaction vessel provided with the catalyst according to claim 7,
decomposing the hydrogen-containing carbon source gas in the reaction vessel to produce hydrogen gas,
the catalyst is reduced by the hydrogen gas, and the reduced catalyst catalyzes the hydrogen-containing carbon source gas to form carbon nanotubes.
9. A carbon nanotube, characterized in that the carbon nanotube is produced by the carbon nanotube production method according to claim 8, and a part thereof has a tube diameter of less than 10 nm.
10. The carbon nanotube according to claim 9,
the tube diameters of all the carbon nano tubes are in the range of 5-15 nm.
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| US20120149824A1 (en) * | 2009-08-21 | 2012-06-14 | Bayer Materialscience Ag | Carbon nanotube agglomerate |
| KR20130094365A (en) * | 2012-02-13 | 2013-08-26 | 금호석유화학 주식회사 | Highly conductive carbon nanotube having bundle moieties with ultra-low bulk density and highly conductive polymer nano-composite using the same |
| US20160160394A1 (en) * | 2013-07-19 | 2016-06-09 | Covestro Deutschland Ag | Method for producing an efficient catalyst for generating multi-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanotube |
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| US20120149824A1 (en) * | 2009-08-21 | 2012-06-14 | Bayer Materialscience Ag | Carbon nanotube agglomerate |
| KR20130094365A (en) * | 2012-02-13 | 2013-08-26 | 금호석유화학 주식회사 | Highly conductive carbon nanotube having bundle moieties with ultra-low bulk density and highly conductive polymer nano-composite using the same |
| US20160160394A1 (en) * | 2013-07-19 | 2016-06-09 | Covestro Deutschland Ag | Method for producing an efficient catalyst for generating multi-walled carbon nanotubes, multi-walled carbon nanotubes and carbon nanotube |
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