CN117563625A - Cobalt-based carbon nanotube catalyst, and preparation method and application thereof - Google Patents
Cobalt-based carbon nanotube catalyst, and preparation method and application thereof Download PDFInfo
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- CN117563625A CN117563625A CN202311528889.6A CN202311528889A CN117563625A CN 117563625 A CN117563625 A CN 117563625A CN 202311528889 A CN202311528889 A CN 202311528889A CN 117563625 A CN117563625 A CN 117563625A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 98
- 239000002041 carbon nanotube Substances 0.000 title claims abstract description 90
- 229910021393 carbon nanotube Inorganic materials 0.000 title claims abstract description 90
- 239000003054 catalyst Substances 0.000 title claims abstract description 77
- 229910017052 cobalt Inorganic materials 0.000 title claims abstract description 50
- 239000010941 cobalt Substances 0.000 title claims abstract description 50
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 238000000034 method Methods 0.000 claims abstract description 34
- 238000006243 chemical reaction Methods 0.000 claims abstract description 20
- PHFQLYPOURZARY-UHFFFAOYSA-N chromium trinitrate Chemical compound [Cr+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PHFQLYPOURZARY-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000001035 drying Methods 0.000 claims abstract description 20
- 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 10
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 claims abstract description 10
- 229940010552 ammonium molybdate Drugs 0.000 claims abstract description 10
- 235000018660 ammonium molybdate Nutrition 0.000 claims abstract description 10
- 239000011609 ammonium molybdate Substances 0.000 claims abstract description 10
- 238000001354 calcination Methods 0.000 claims abstract description 10
- 238000005229 chemical vapour deposition Methods 0.000 claims abstract description 10
- 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 10
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims abstract description 10
- 229940071125 manganese acetate Drugs 0.000 claims abstract description 10
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 claims abstract description 10
- 239000002994 raw material Substances 0.000 claims abstract description 7
- 238000000227 grinding Methods 0.000 claims abstract description 4
- 239000007789 gas Substances 0.000 claims description 35
- 239000000243 solution Substances 0.000 claims description 26
- 239000002904 solvent Substances 0.000 claims description 20
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 16
- 239000002245 particle Substances 0.000 claims description 15
- 238000001694 spray drying Methods 0.000 claims description 13
- 239000010453 quartz Substances 0.000 claims description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 239000008247 solid mixture Substances 0.000 claims description 12
- 239000000203 mixture Substances 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 9
- 239000007921 spray Substances 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 229910052786 argon Inorganic materials 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 8
- 229910021641 deionized water Inorganic materials 0.000 claims description 8
- 238000005469 granulation Methods 0.000 claims description 8
- 230000003179 granulation Effects 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 6
- 238000005303 weighing Methods 0.000 claims description 6
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 239000001257 hydrogen Substances 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 238000002156 mixing Methods 0.000 claims description 5
- 150000001298 alcohols Chemical class 0.000 claims description 3
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 claims description 3
- 239000012300 argon atmosphere Substances 0.000 claims description 3
- 150000004945 aromatic hydrocarbons Chemical class 0.000 claims description 3
- 238000009835 boiling Methods 0.000 claims description 3
- 238000004523 catalytic cracking Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 claims description 3
- 239000011261 inert gas Substances 0.000 claims description 3
- LYGJENNIWJXYER-UHFFFAOYSA-N nitromethane Chemical compound C[N+]([O-])=O LYGJENNIWJXYER-UHFFFAOYSA-N 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 238000003892 spreading Methods 0.000 claims description 3
- 230000007480 spreading Effects 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 3
- 239000002699 waste material Substances 0.000 claims description 3
- GMACPFCYCYJHOC-UHFFFAOYSA-N [C].C Chemical compound [C].C GMACPFCYCYJHOC-UHFFFAOYSA-N 0.000 claims description 2
- 239000012159 carrier gas Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 abstract description 6
- 238000007306 functionalization reaction Methods 0.000 abstract description 5
- 238000003786 synthesis reaction Methods 0.000 abstract description 5
- 229910001429 cobalt ion Inorganic materials 0.000 description 11
- XLJKHNWPARRRJB-UHFFFAOYSA-N cobalt(2+) Chemical compound [Co+2] XLJKHNWPARRRJB-UHFFFAOYSA-N 0.000 description 11
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 10
- 229910052799 carbon Inorganic materials 0.000 description 8
- 238000000889 atomisation Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000004480 active ingredient Substances 0.000 description 2
- 238000001241 arc-discharge method Methods 0.000 description 2
- 125000004432 carbon atom Chemical group C* 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910000000 metal hydroxide Inorganic materials 0.000 description 2
- 150000004692 metal hydroxides Chemical class 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000010891 electric arc Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000005243 fluidization Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 238000003801 milling Methods 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
Classifications
-
- 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
- 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
- B01J23/8898—Manganese, technetium or rhenium containing also molybdenum
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
- B01J37/0027—Powdering
- B01J37/0045—Drying a slurry, e.g. spray drying
-
- 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
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
- B01J37/082—Decomposition and pyrolysis
Abstract
The invention relates to a cobalt-based carbon nanotube catalyst and a preparation method and application thereof, wherein the cobalt-based carbon nanotube catalyst comprises the following raw materials in parts by mass: 30-70 parts of cobalt nitrate, 15-60 parts of manganese acetate, 30-80 parts of aluminum nitrate, 1-10 parts of ammonium molybdate and 1-10 parts of chromium nitrate, wherein the cobalt-based carbon nanotube catalyst is used for preparing carbon nanotubes by a chemical vapor deposition method. The invention relates to the technical field of carbon nanotube catalysts. According to the preparation method, the cobalt-based catalyst is prepared by drying, grinding and calcining the cobalt nitrate, manganese acetate, aluminum nitrate, ammonium molybdate and chromium nitrate raw materials, and the conversion rate and multiplying power of the cobalt-based catalyst are high by strictly controlling the technological conditions of each step and the proportion of each component, and the prepared carbon nano tube has a high-end array form and high conductivity. Meanwhile, the cobalt catalyst can be compounded with other catalysts to realize the synthesis and functionalization of the carbon nano tube.
Description
Technical Field
The invention relates to the technical field of carbon nanotube catalysts, in particular to a cobalt-based carbon nanotube catalyst, a preparation method and application thereof.
Background
The carbon nano tube is a nano material with excellent performance, has the characteristics of high electrical conductivity, high strength, high thermal conductivity and the like, and has wide application prospect in the fields of material science, electronics, catalysts and the like. However, the preparation method of carbon nanotubes has been a hot spot of research, and searching for an efficient and economical preparation method has been pursued by scientists.
Currently, methods for preparing carbon nanotubes mainly include an arc discharge method, a laser evaporation method and a chemical vapor deposition method. The method for preparing the carbon nano tube by arc discharge or laser evaporation has higher reaction temperature and relatively high process requirement. The chemical vapor deposition method has the advantages of lower working temperature, simpler process and equipment, lower cost, controllable growth of the carbon tube and the like, thereby replacing the methods of arc discharge method, laser evaporation method and the like, being used for semi-industrialized and industrialized production and meeting the industrial requirements on the carbon nano tube composite material.
The key point of the chemical vapor deposition method is the preparation and selection of the catalyst, and the components, morphology, physical and chemical properties and the like of the catalyst affect the structure and properties of the finally obtained carbon nanotube to different degrees. The conversion rate of the currently commonly adopted iron-based carbon nanotube catalyst is low, and the high-end array effect is poor, so that the performance of the carbon nanotubes is reduced.
Disclosure of Invention
According to the shortcomings of the prior art, the invention aims to provide a cobalt-based carbon nanotube catalyst, a preparation method and application thereof, so as to solve the problems in the prior art.
The technical aim of the invention is realized by the following technical scheme:
the cobalt-based carbon nanotube catalyst comprises the following raw materials in parts by mass: 30 to 70 parts of cobalt nitrate, 15 to 60 parts of manganese acetate, 30 to 80 parts of aluminum nitrate, 1 to 10 parts of ammonium molybdate and 1 to 10 parts of chromium nitrate.
By adopting the technical scheme, the raw materials are proportioned, so that the active ingredients in the catalyst are cobalt ions, the conversion rate and multiplying power of the cobalt ions are high, and the performance of the carbon nano tube can be improved. The cobalt metal has low cost and high economic benefit. Meanwhile, the cobalt catalyst can be compounded with other catalysts to realize the synthesis and functionalization of the carbon nano tube.
In the growth process of the carbon nano tube, cobalt ions not only play a role of a catalyst, but also can regulate and control the diameter and the length of the carbon nano tube. Research shows that the concentration, temperature, reaction time and other factors of cobalt ions have important influence on the growth of the carbon nano tube. The directional growth of the carbon nano tube can be realized by properly regulating the parameters, and the performance of the carbon nano tube is further optimized.
The preparation method of the cobalt-based carbon nanotube catalyst comprises the following steps:
s1, weighing 30-70 parts of cobalt nitrate, 15-60 parts of manganese acetate and 30-80 parts of aluminum nitrate, dissolving in a solvent, and uniformly stirring to completely dissolve a solute to form a clear solution A;
s2, weighing 1-10 parts of ammonium molybdate and 1-10 parts of chromium nitrate, dissolving in a solvent, and uniformly stirring to completely dissolve a solute to form a clear solution B;
s3, uniformly mixing the solution A and the solution B, and stirring to completely react the clarified solution A and the clarified solution B to obtain a mixed solution C;
s4, removing the solvent in the mixed solution C by spray granulation or spray drying by using a drying gas with the temperature of 300-500 ℃ through a nozzle type or a disk type sprayer to obtain a solid mixture D;
s5, grinding the solid mixture D obtained in the step S4, and then sorting to obtain mixture particles E with the particle size range of 40-70 mu m;
s6, further supplementing the dry mixture particles E in an environment of 80-300 ℃;
s7, calcining the mixture particles E obtained in the step S6 for 3 to 5 hours under the air participation and the temperature environment of 300 to 700 ℃ to remove decomposed gas and obtain the catalyst F.
Through adopting the technical scheme, cobalt nitrate, manganese acetate and aluminum nitrate are dissolved in deionized water to form a clear solution A, ammonium molybdate and chromium nitrate are dissolved in the deionized water to form a clear solution B, the solution A and the solution B are mixed and dried, and then are separated and calcined, so that metal hydroxide is decomposed into metal oxide, and finally, the cobalt-based carbon nano tube catalyst is formed, the conversion rate and the multiplying power are high, and the prepared carbon nano tube has a high-end array form and high conductivity.
The present invention may be further configured in a preferred example to: after the step S7, the catalyst F is placed in a reaction tank filled with a reducing gas so that the catalyst F is reduced, and the ambient temperature is 200 to 750 ℃.
The present invention may be further configured in a preferred example to: the part of the solvent in the step S1 is 200-300 parts, and the part of the solvent in the step S2 is 30-70 parts.
The present invention may be further configured in a preferred example to: in the step S4, the spray granulation or spray drying is performed as follows:
the rotating disk of the atomizer has a rotating speed of 5000-15000 rpm, a single-component atomizing nozzle or a double-component atomizing nozzle is used, the pressure difference of the nozzles is 40X 105-70X 105Pa, and inert gas or air is mixed in the atomizing process, wherein the ratio of the gas mass flow rate to the liquid mass flow rate is (0.1-2) to 1.
The present invention may be further configured in a preferred example to: and the waste hot gas generated by the supplementary drying in the step S6 and the calcining in the step S7 is returned to the step S4 for heat exchange, so that the energy consumption of spray drying is reduced.
The present invention may be further configured in a preferred example to: if the solid mixture D obtained in the step S4 has a tendency to adhere, the supplementary drying in the step S6 is 80-120 ℃; if the solid mixture D obtained in step S4 has no tendency to adhere, the additional drying in step S6 is 150 to 300 ℃.
The present invention may be further configured in a preferred example to: the solvent in the step S1 and the step S2 is selected from at least one of the following: deionized water, low boiling aliphatic and aromatic hydrocarbons, alcohols, or nitromethane.
The application of the cobalt-based carbon nanotube catalyst is that the cobalt-based carbon nanotube catalyst is used for preparing carbon nanotubes by a chemical vapor deposition method.
The present invention may be further configured in a preferred example to: the preparation method of the carbon nano tube by the chemical vapor deposition method specifically comprises the following steps:
s11, uniformly spreading cobalt-based carbon nanotube catalyst powder in a quartz boat, and placing the quartz boat in a constant temperature area in the middle of a quartz reaction tube;
s12, introducing argon into the quartz reaction tube, raising the temperature to 400-500 ℃ at a heating rate of 10 ℃/min, and introducing hydrogen for 2-4 hours at a temperature of 50-200 mL/min;
s13, introducing mixed gas into the cobalt-based carbon nano tube catalyst according to the volume ratio of methane carbon source gas to argon carrier gas of 5:1, and carrying out catalytic cracking reaction for 0.5-3 hours at the temperature of 450-550 ℃;
s14, cooling the furnace temperature to room temperature in the argon atmosphere to obtain a carbon nanotube product, wherein the multiplying power of the prepared carbon nanotube is 50-70 times.
In summary, the present invention includes at least one of the following beneficial technical effects:
the invention provides a cobalt-based carbon nanotube catalyst and a preparation method and application thereof. Meanwhile, the cobalt catalyst can be compounded with other catalysts to realize the synthesis and functionalization of the carbon nano tube.
Drawings
FIG. 1 is a flow chart of a cobalt-based carbon nanotube catalyst, a preparation method and an application thereof;
FIG. 2 is an SEM image (30 μm on the scale) of a carbon nanotube prepared by the catalysis of a cobalt-based carbon nanotube catalyst according to the present invention;
FIG. 3 is an SEM image (graph scale 5 μm) of a carbon nanotube prepared by the catalysis of a cobalt-based carbon nanotube catalyst according to the present invention.
Detailed Description
In order to more clearly illustrate the general inventive concept, a detailed description is given below by way of example with reference to the accompanying drawings.
In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like indicate orientations or positional relationships based on the orientation or positional relationships shown in the drawings, merely to facilitate describing the present invention and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; the device can be mechanically connected, electrically connected and communicated; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. In the description of the present specification, the description with reference to the terms "one aspect," "some aspects," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the aspect or example is included in at least one aspect or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily for the same scheme or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more aspects or examples.
Example 1:
referring to fig. 1 to 3, the cobalt-based carbon nanotube catalyst disclosed by the invention comprises the following raw materials in parts by mass: 50 parts of cobalt nitrate, 40 parts of manganese acetate, 60 parts of aluminum nitrate, 5 parts of ammonium molybdate and 5 parts of chromium nitrate.
The raw materials are proportioned, so that the active ingredients in the catalyst are cobalt ions, the conversion rate and multiplying power of the cobalt ions are high, and the performance of the carbon nano tube can be improved. The cobalt metal has low cost and high economic benefit. Meanwhile, the cobalt catalyst can be compounded with other catalysts to realize the synthesis and functionalization of the carbon nano tube.
In the growth process of the carbon nano tube, cobalt ions not only play a role of a catalyst, but also can regulate and control the diameter and the length of the carbon nano tube. Research shows that the concentration, temperature, reaction time and other factors of cobalt ions have important influence on the growth of the carbon nano tube, and the directional growth of the carbon nano tube can be realized by properly regulating and controlling the parameters, so that the performance of the carbon nano tube is further optimized.
Example 2:
referring to fig. 1, the method for preparing the cobalt-based carbon nanotube catalyst in example 1 includes the steps of:
s1, weighing 50 parts of cobalt nitrate, 40 parts of manganese acetate and 60 parts of aluminum nitrate, dissolving in a solvent, and uniformly stirring to completely dissolve a solute to form a clear solution A.
S2, weighing 5 parts of ammonium molybdate and 5 parts of chromium nitrate, dissolving in a solvent, and uniformly stirring to completely dissolve the solute to form a clear solution B.
The part of the solvent in the step S1 is 200-300 parts, and the part of the solvent in the step S2 is 30-70 parts.
The solvent in the step S1 and the step S2 is selected from at least one of the following: deionized water, low boiling aliphatic and aromatic hydrocarbons, alcohols or nitromethane, with deionized water being the preferred solvent in this example.
And S3, uniformly mixing the solution A and the solution B, and stirring to completely react the clarified solution A and the clarified solution B to obtain a mixed solution C.
S4, removing the solvent in the mixed solution C by spray granulation or spray drying by using a drying gas with the temperature of 300-500 ℃ through a nozzle type or a disk type sprayer to obtain a solid mixture D. The temperature of the off-gas (mixture of drying gas and solvent vapor) is controlled to be between 80 and 120 ℃, and since the off-gas comes from the dryer used for the spray granulation or spray drying process, the discharge temperature of the off-gas is controlled so that the solids formed in the spray granulation or spray drying do not form a tacky phase at the outlet of the dryer.
In the step S4, the spray granulation or spray drying is performed as follows:
the rotation speed of the atomizer turntable is 5000-15000 rpm, and the advantages of disk atomization are saving of compressed gas and liquid inlet pressure and local distribution of spray drop width in the atomizer tower with only one atomizing mechanism.
With single-component atomizing nozzles or two-component atomizing nozzles, in the case of single-component atomization, the energy required for generating the droplets (surface energy) comes only from the liquid, which is ultimately transmitted through small nozzle openings with high entry pressure and correspondingly high velocity. In the case of two-component atomization, the energy required for generating the droplets does not or exclusively come from the liquid, but additionally, the gas is brought into contact with the liquid jet under high pressure, the liquid entry pressure being significantly lower than in the case of one-component atomization or can be ignored entirely.
The choice of a suitable method for a given atomization target additionally depends on the desired throughput. After the corresponding preliminary tests have been carried out, it is generally possible to determine the exact operating parameters, since the interdependence of the parameters is complex. In this example, the pressure difference across the nozzle was 40X 105 to 70X 105Pa.
Inert gas or air, preferably nitrogen, is mixed in the atomization process, wherein the ratio of the gas mass flow to the liquid mass flow is (0.1-2) to 1. The smaller air volume is achieved mainly in two-component nozzles with internal mixing and liquid inlet pressure and contains the risk of nozzle clogging in addition to compressed gas saving. In the case of two-component nozzles with external mixing, there is less risk of nozzle clogging, but more atomizing gas must generally be used.
The gas inlet temperature of the drying gas used for drying is chosen as high as possible in order to achieve as high a drying efficiency as possible, optimally in the range of 300-500 c, if there are relevant safety considerations or quality effects due to thermal decomposition of the blown-back drying material or adhesion in the gas inlet region, the drying gas temperature can be adjusted to between 150-600 c.
S5, grinding the solid mixture D obtained in the step S4, and then sorting to obtain mixture particles E with the particle size range of 40-70 mu m. The smallest possible particle size distribution is particularly technically advantageous for catalysts used in fluidized beds, since there is generally only a relatively narrow velocity range in which the heavier large CNT aggregates do not lose fluidization in the reactor, while at the same time fine catalyst particles do not escape from above the bed, i.e. in which steady-state operation of the reactor is possible without special recirculation measures.
Additional process steps, such as dust removal, compaction, may be inserted prior to classification. The milling step may also be removed when the intermediate obtained by spray drying has obtained the desired particle size.
S6, further supplementing the dry mixture particles E in the environment of 80-300 ℃. And the waste hot gas generated by the supplementary drying in the step S6 and the calcining in the step S7 is returned to the step S4 for heat exchange, so that the energy consumption of spray drying is reduced.
If the solid mixture D obtained in the step S4 has a tendency to adhere, the supplementary drying temperature in the step S6 is 80 to 120℃in order to prevent melting. In the case of such products, in the aforementioned spray drying, it is necessary to carry out at low exhaust gas temperatures and high residual moisture contents in order to avoid the melting process and, correspondingly, the formation of a tacky phase, so that additional drying is generally unavoidable.
If the solid mixture D obtained in step S4 has no tendency to adhere, the supplementary drying temperature in step S6 is 150 to 300℃in order to remove the water bound in the form of a hydrate shell prior to calcination.
S7, calcining the mixture particles E obtained in the step S6 for 3 to 5 hours under the air participation and the temperature environment of 300 to 700 ℃ to remove decomposed gas and obtain the catalyst F. The calcination process may be carried out in a fixed bed, a shelf oven, a fluidized bed, a moving bed, a rotary drum oven, a riser, a downcomer, a circulation system. The calcination time also depends on the choice of the reaction equipment and is adapted accordingly.
After the step S7, the catalyst F is placed in a reaction tank filled with a reducing gas so that the catalyst F is reduced, and the ambient temperature is 200 to 750 ℃. The reducing gas is preferably hydrogen.
Cobalt ions, as an important catalyst, can play a key role in the preparation of carbon nanotubes. At a proper temperature, cobalt ions are decomposed by a catalytic carbon source, so that the preparation of the carbon nano tube is realized.
Example 3:
referring to fig. 2 and 3, the application of the cobalt-based carbon nanotube catalyst described in example 1 or the cobalt-based carbon nanotube catalyst prepared by the method for preparing the cobalt-based carbon nanotube catalyst described in example 2 is as follows:
the cobalt-based carbon nanotube catalyst prepares carbon nanotubes by a chemical vapor deposition method. In the preparation process of the cobalt ion catalytic carbon nano tube, a proper carbon source is needed to be selected first. Common carbon sources include organic materials such as ethylene and methane, and solid carbon sources such as gas phase carbon black and the like can also be used. Then, under the action of the catalyst, the carbon source is decomposed at a proper temperature to generate carbon atoms, and the carbon atoms form a core of the carbon nano tube on the surface of the catalyst. In the present invention, the carbon source is preferably methane.
The preparation method of the carbon nano tube by the chemical vapor deposition method specifically comprises the following steps:
s11, uniformly spreading cobalt-based carbon nanotube catalyst powder in a quartz boat, and placing the quartz boat in a constant temperature area in the middle of a quartz reaction tube.
S12, introducing argon into the quartz reaction tube, heating to 400 ℃ at a heating rate of 10 ℃/min, introducing hydrogen at 100mL/min, closing the hydrogen after 3 hours, and heating to 500 ℃ at 10 ℃/min under the protection of argon.
S13, introducing methane as a carbon source gas, enabling the flow rate of argon to be 100mL/min and the flow rate of methane and argon to be 300mL/min, and stopping introducing methane after catalytic cracking reaction for 1 hour at 500 ℃.
S14, cooling the furnace temperature to room temperature in an argon atmosphere to obtain a carbon nanotube product, wherein the multiplying power of the prepared carbon nanotube is 50-70 times, and the obtained cobalt-based carbon nanotube electron microscope pictures are shown in fig. 2 and 3.
According to the preparation method of the catalyst, cobalt nitrate, manganese acetate and aluminum nitrate are dissolved in deionized water to form a clear solution A, ammonium molybdate and chromium nitrate are dissolved in the deionized water to form a clear solution B, the solution A and the solution B are mixed and dried, and then separated and calcined, so that metal hydroxide is decomposed into metal oxide, and finally the cobalt-based carbon nano tube catalyst is formed, the conversion rate and the multiplying power are high, and the prepared carbon nano tube has a high-end array form and high conductivity. Meanwhile, the cobalt catalyst can be compounded with other catalysts to realize the synthesis and functionalization of the carbon nano tube.
The embodiments of the present invention are all preferred embodiments of the present invention, and are not intended to limit the scope of the present invention in this way, therefore: all equivalent changes in structure, shape and principle of the invention should be covered in the scope of protection of the invention.
Claims (10)
1. A cobalt-based carbon nanotube catalyst is characterized in that: the material comprises the following raw materials in parts by weight: 30 to 70 parts of cobalt nitrate, 15 to 60 parts of manganese acetate, 30 to 80 parts of aluminum nitrate, 1 to 10 parts of ammonium molybdate and 1 to 10 parts of chromium nitrate.
2. A method for preparing a cobalt-based carbon nanotube catalyst according to claim 1, characterized in that: the method comprises the following steps:
s1, weighing 30-70 parts of cobalt nitrate, 15-60 parts of manganese acetate and 30-80 parts of aluminum nitrate, dissolving in a solvent, and uniformly stirring to completely dissolve a solute to form a clear solution A;
s2, weighing 1-10 parts of ammonium molybdate and 1-10 parts of chromium nitrate, dissolving in a solvent, and uniformly stirring to completely dissolve a solute to form a clear solution B;
s3, uniformly mixing the solution A and the solution B, and stirring to completely react the clarified solution A and the clarified solution B to obtain a mixed solution C;
s4, removing the solvent in the mixed solution C by spray granulation or spray drying by using a drying gas with the temperature of 300-500 ℃ through a nozzle type or a disk type sprayer to obtain a solid mixture D;
s5, grinding the solid mixture D obtained in the step S4, and then sorting to obtain mixture particles E with the particle size range of 40-70 mu m;
s6, further supplementing the dry mixture particles E in an environment of 80-300 ℃;
s7, calcining the mixture particles E obtained in the step S6 for 3 to 5 hours under the air participation and the temperature environment of 300 to 700 ℃ to remove decomposed gas and obtain the catalyst F.
3. The method for preparing a cobalt-based carbon nanotube catalyst according to claim 2, wherein: after the step S7, the catalyst F is placed in a reaction tank filled with a reducing gas so that the catalyst F is reduced, and the ambient temperature is 200 to 750 ℃.
4. The method for preparing a cobalt-based carbon nanotube catalyst according to claim 2, wherein: the part of the solvent in the step S1 is 200-300 parts, and the part of the solvent in the step S2 is 30-70 parts.
5. The method for preparing a cobalt-based carbon nanotube catalyst according to claim 2, wherein: in the step S4, the spray granulation or spray drying is performed as follows:
the rotating disk of the atomizer has a rotating speed of 5000-15000 rpm, a single-component atomizing nozzle or a double-component atomizing nozzle is used, the pressure difference of the nozzles is 40X 105-70X 105Pa, and inert gas or air is mixed in the atomizing process, wherein the ratio of the gas mass flow rate to the liquid mass flow rate is (0.1-2) to 1.
6. The method for preparing a cobalt-based carbon nanotube catalyst according to claim 5, wherein: and the waste hot gas generated by the supplementary drying in the step S6 and the calcining in the step S7 is returned to the step S4 for heat exchange, so that the energy consumption of spray drying is reduced.
7. The method for preparing a cobalt-based carbon nanotube catalyst according to claim 2, wherein: if the solid mixture D obtained in the step S4 has a tendency of adhesion, the supplementary drying temperature in the step S6 is 80-120 ℃; if the solid mixture D obtained in step S4 has no tendency to adhere, the supplementary drying temperature in step S6 is 150 to 300 ℃.
8. The method for preparing a cobalt-based carbon nanotube catalyst according to claim 2, wherein: the solvent in the step S1 and the step S2 is selected from at least one of the following: deionized water, low boiling aliphatic and aromatic hydrocarbons, alcohols, or nitromethane.
9. Use of a cobalt-based carbon nanotube catalyst according to claim 1 or a cobalt-based carbon nanotube catalyst produced by the production method according to any one of claims 2 to 8, characterized in that: the cobalt-based carbon nanotube catalyst prepares carbon nanotubes by a chemical vapor deposition method.
10. The use of a cobalt-based carbon nanotube catalyst according to claim 9, wherein: the preparation method of the carbon nano tube by the chemical vapor deposition method specifically comprises the following steps:
s11, uniformly spreading cobalt-based carbon nanotube catalyst powder in a quartz boat, and placing the quartz boat in a constant temperature area in the middle of a quartz reaction tube;
s12, introducing argon into the quartz reaction tube, raising the temperature to 400-500 ℃ at a heating rate of 10 ℃/min, and introducing hydrogen for 2-4 hours at a temperature of 50-200 mL/min;
s13, introducing mixed gas into the cobalt-based carbon nano tube catalyst according to the volume ratio of methane carbon source gas to argon carrier gas of 5:1, and carrying out catalytic cracking reaction for 0.5-3 hours at the temperature of 450-550 ℃;
s14, cooling the furnace temperature to room temperature in the argon atmosphere to obtain a carbon nanotube product, wherein the multiplying power of the prepared carbon nanotube is 50-70 times.
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