CN113209969A - Catalyst for preparing carbon nano tube and preparation method and application thereof - Google Patents

Catalyst for preparing carbon nano tube and preparation method and application thereof Download PDF

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CN113209969A
CN113209969A CN202110404912.5A CN202110404912A CN113209969A CN 113209969 A CN113209969 A CN 113209969A CN 202110404912 A CN202110404912 A CN 202110404912A CN 113209969 A CN113209969 A CN 113209969A
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catalyst
present
salt
active component
preparing
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周平
沈跃成
张翼
王昆明
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Foshan Griffin New Energy Co ltd
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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
    • B01J23/70—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
    • B01J23/78—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 alkali- or alkaline earth metals
    • 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
    • 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
    • B01J37/086—Decomposition of an organometallic compound, a metal complex or a metal salt of a carboxylic acid
    • 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
    • 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
    • C01B2202/04—Nanotubes with a specific amount of walls
    • 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
    • C01B2202/32—Specific surface area

Abstract

The invention discloses a catalyst for preparing a carbon nano tube, a preparation method and application thereof. The catalyst comprises a porous flaky carrier and an active component dispersed on the porous flaky carrier; wherein the active component comprises a transition metal element. The invention provides a porous flaky catalyst which is suitable for preparing a carbon nano tube, can meet the preparation requirement of a low-wall array carbon nano tube, can improve the growth rate of the carbon nano tube, improves the industrial production efficiency and has wide application prospect.

Description

Catalyst for preparing carbon nano tube and preparation method and application thereof
Technical Field
The invention relates to the technical field of carbon nano materials, in particular to a catalyst for preparing a carbon nano tube and a preparation method and application thereof.
Background
The multi-wall carbon nano tube has two microscopic morphologies of conglomerate and directional array. In the arrayed carbon nanotubes, all the carbon nanotubes have a larger aspect ratio and a more uniform orientation, which is advantageous to maintain a larger size during dispersion, compared to the carbon nanotubes in the form of agglomeratesThe length-diameter ratio of the conductive material can better exert the conductive performance of the conductive material. Because the oligo-wall array carbon nano-tube with the wall number less than 7 has better conductivity and lower addition amount, the oligo-wall array carbon nano-tube is more and more favored by the industry, but the oligo-wall array carbon nano-tube is limited by the catalyst technology, and the array carbon nano-tube which can be produced in mass at present has larger tube wall number (the wall number is more than 6, and the specific surface area is less than 500 m)2In terms of/g). The current methods for preparing the oligowall array carbon nanotube catalyst mainly include four methods: 1) active components such as Fe, Co or Ni are loaded on the surface of the silicon wafer; 2) impregnation method, in which a catalyst is supported on powder layers of vermiculite, aluminum hydroxide, etc. or on the surface thereof; 3) a coprecipitation method; 4) spray pyrolysis method. Wherein only the catalyst prepared by coprecipitation method (combined with freeze drying) and spray pyrolysis method grows carbon tubes with the wall number less than 7 (the specific surface area is more than 500 m)2G) and the rate (mass of carbon nanotubes grown per unit mass of catalyst) is more than 5 times.
From the analysis of the growth mechanism of the carbon nano tube, the particle size of the active component, the distribution of the active component and the primary particle morphology of the catalyst need to be controlled for preparing the carbon nano tube with the oligowall array. The smaller the size of the active component in the catalyst is, the more uniform the distribution is, the more active sites can be used for growing the carbon nano tube, the fewer the number of the obtained carbon nano tube walls is, and the higher the multiplying power is; in the aspect of catalyst morphology, in order to obtain the array carbon nano tube, the morphology of primary particles of the catalyst needs to be a sheet structure, and loose packing mode is adopted among the particles, so that the carbon nano tube has a proper growth space. The coprecipitation method simultaneously precipitates the carrier component and the active component to form flaky particles, and the active component is ensured to be uniformly distributed in the flaky particles in small size through physical separation of the inert carrier; the flake particles are then agglomerated in loose packing by freeze-drying, and the catalyst can pass through a high-space-velocity operation process in a fluidized bed, and the growth rate of the carbon nanotubes is high. The spray pyrolysis method controls the size and distribution of active components by the principle of restraining segregation by micro-droplets, and the stacking among primary particles is particularly loose due to gas generated in the thermal decomposition process and gas powder formed by spray carriers, and the apparent density is less than 0.1g/cm3The multiplying power of the grown carbon nano tube with the oligowall array is extremely high and reaches 90 times at most.
The prior art for preparing the carbon nanotube with the oligowalled array mainly has the following defects:
1) the coprecipitation method generates a large amount of wastewater in the process of preparing the catalyst, so that the environmental protection cost is high; on the other hand, freeze drying is necessary to ensure the loose packing of the primary particles, the process is time-consuming, the catalyst production efficiency is low, and the industrial application of the method is limited.
2) When the catalyst is prepared by the spray pyrolysis method, the amount of generated wastewater is less than 10% of that of the coprecipitation method, but the preparation process needs complex spray pyrolysis equipment, the size of micro-droplets is strictly controlled, and the production cost is high; in addition, the apparent density of the catalyst is less than 0.1g/cm3And the fluidized operation process with high space velocity is difficult to adopt, so that the efficiency of growing the carbon nano tubes by a single set of reactor is limited.
In order to reduce the process and technical complexity in the production process of the oligowalled array carbon nanotube catalyst, to be compatible with the existing high-temperature calcining furnace equipment, and to improve the preparation efficiency of the catalyst and the growth efficiency of the carbon nanotubes, a new method is needed to control the particle size and distribution of active components, the appearance of primary particles or the stacking mode.
Disclosure of Invention
The present invention is directed to solving at least one of the above problems in the prior art. Therefore, one of the objectives of the present invention is to provide a catalyst for preparing carbon nanotubes, which can grow an average wall number of 3-4 and a specific surface area of more than 600m within 30-60 min2The/g and the multiplying power is more than 40 times. The second object of the present invention is to provide a process for preparing such a catalyst. The invention also aims to provide the application of the catalyst.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a first aspect of the present invention provides a catalyst comprising a porous sheet-like support and an active component dispersed on the porous sheet-like support; the active component includes a transition metal element.
According to some embodiments of the catalyst of the present invention, the transition metal element in the active component comprises at least one of Fe, Co, Ni, Mo, Cu, Mn.
According to some embodiments of the catalyst of the present invention, the catalyst has an apparent density of 0.1g/cm3～0.5g/cm3。
According to some embodiments of the catalyst of the present invention, the catalyst has a microscopic morphology in the form of porous platelets.
According to some embodiments of the catalyst of the present invention, the catalyst has a particle size of 50 mesh to 200 mesh.
According to some embodiments of the catalyst of the present invention, the catalyst is prepared from components comprising: active component salt, inactive component salt, organic ligand, sheet-shaped template agent and thickening agent.
According to some embodiments of the catalyst of the present invention, the active component salt comprises a transition metal salt. Wherein the transition metal element in the transition metal salt is as described above.
According to some embodiments of the catalyst of the present invention, the active component salt comprises a transition metal water-soluble salt.
According to some embodiments of the catalyst of the present invention, the inactive component salt comprises at least one of an Al salt, a Mg salt.
According to some embodiments of the catalyst of the present invention, the inactive component salt comprises at least one of a water soluble salt of Al, a water soluble salt of Mg.
According to some embodiments of the catalyst of the present invention, the plate-like templating agent comprises a plate-like material comprising at least one of Al, Mg. The flaky template agent refers to a material with flaky primary particles.
According to some embodiments of the catalyst of the present invention, the plate-like templating agent comprises plate-like Al (OH)3Mg (OH) in the form of flakes2And at least one of flaky aluminum-magnesium hydrotalcite.
According to some embodiments of the catalyst of the present invention, the plate-like templating agent further comprises Si.
According to some embodiments of the catalyst of the present invention, the organic ligand comprises a polycarboxylic acid, or a polycarboxylic acid and a polyamine.
According to some embodiments of the catalyst of the present invention, the polycarboxylic acid comprises at least one of citric acid, ethylenediaminetetraacetic acid, polyacrylic acid.
According to some embodiments of the catalyst of the present invention, the thickening agent comprises at least one of guar gum, polyacrylamide, carob gum, glucomannan, xanthan gum, collagen.
According to some embodiments of the catalyst of the present invention, the thickener comprises at least one of guar gum, carob gum, xanthan gum.
According to some embodiments of the catalyst of the present invention, the components for preparing the catalyst further comprise a solvent.
According to some embodiments of the catalyst of the present invention, the solvent comprises water.
According to some embodiments of the catalyst of the present invention, the molar ratio of the metal atoms of the plate-like templating agent to the total metal atoms of the catalyst is (5-50): 100. the content of the flaky template agent is too low, only mixed catalyst with the flaky shape of partial catalyst can be obtained, and the grown carbon nano tube is a mixture of the array tube and the winding tube; the content of the sheet template agent is too high, the prepared catalyst has few pore structures, high apparent density and low growth rate of the carbon nano tube.
According to some embodiments of the catalyst of the present invention, the number of moles of metal atoms in the active component is ≦ the total number of moles of metal atoms in the inactive component salt and the platelet template.
A second aspect of the present invention provides a process for preparing a catalyst according to the first aspect of the present invention, comprising the steps of:
1) mixing active component salt, inactive component salt and organic ligand in a solvent to obtain a metal organic complex solution;
2) mixing the metal organic complex solution with a flaky template agent to obtain a dispersion liquid;
3) mixing the dispersion liquid with a thickening agent to obtain a precursor dispersion liquid;
4) and calcining the precursor dispersion liquid to obtain the catalyst.
According to some embodiments of the method of preparing a catalyst of the present invention, in the step 1), the solvent is water.
According to some embodiments of the method of preparing a catalyst of the present invention, the temperature of mixing in step 1) is 40 ℃ to 90 ℃.
According to some embodiments of the method for preparing the catalyst of the present invention, in the step 1), the mixing temperature is 50 ℃ to 80 ℃.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 1), the mixing time is greater than or equal to 30 min.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 1), the mixing time is 30min to 60 min.
According to some embodiments of the method of preparing a catalyst of the present invention, in the step 1), the mixing is performed by stirring.
According to some embodiments of the method of preparing a catalyst of the present invention, the mixing temperature in the step 2) is 40 ℃ to 90 ℃.
According to some embodiments of the method for preparing the catalyst of the present invention, in the step 2), the mixing temperature is 50 ℃ to 80 ℃.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 2), the mixing time is 60min or more.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 2), the mixing time is 60min to 120 min.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 2), the mixing is performed by stirring.
According to some embodiments of the method for preparing a catalyst of the present invention, the mixing temperature in the step 3) is 40 to 90 ℃.
According to some embodiments of the method for preparing the catalyst of the present invention, in the step 3), the mixing temperature is 50 ℃ to 80 ℃.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 3), the mixing time is 60min or more.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 3), the mixing time is 60min to 120 min.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 3), the mixing is performed by stirring.
According to some embodiments of the method of preparing a catalyst of the present invention, the precursor dispersion has a viscosity of 1000 to 100000 mPa-s at 25 ℃. The viscosity of the precursor dispersion liquid is too low, and the flaky carrier is easy to settle in the calcining process, so that the catalyst is not uniform; the viscosity of the precursor dispersion is too high, the material transfer is difficult, and the process operability is poor.
According to some embodiments of the method of preparing a catalyst of the present invention, the precursor dispersion has a viscosity of 3000mPa · s to 30000mPa · s at 25 ℃.
According to further embodiments of the method of preparing a catalyst of the present invention, the precursor dispersion has a viscosity of 2000mPa · s to 20000mPa · s at 25 ℃.
According to some embodiments of the method for preparing a catalyst of the present invention, in the step 4), the calcination temperature is 300 ℃ to 600 ℃.
According to some embodiments of the method for preparing the catalyst of the present invention, in the step 4), the calcination temperature is 450 to 500 ℃.
According to some embodiments of the method of preparing a catalyst of the present invention, in the step 4), the calcination is performed in a high temperature furnace.
According to some embodiments of the method of preparing a catalyst of the present invention, the step 4) further comprises a step of crushing after the calcination.
According to some embodiments of the method of preparing a catalyst of the present invention, the crushing is crushing the product obtained by calcination to 50 mesh to 200 mesh.
The third aspect of the present invention provides a use of a catalyst for preparing a carbon nanotube, wherein the catalyst is the catalyst according to the first aspect of the present invention, or is prepared by the preparation method according to the second aspect of the present invention.
According to some embodiments of the use of the present invention, the carbon nanotubes are prepared by catalyzing a carbon source with a catalyst.
According to some embodiments of the use of the invention, the carbon source comprises a hydrocarbon gas.
According to some embodiments of the use of the present invention, the carbon source comprises at least one of propylene, ethylene, acetylene, butane, propane, ethane, natural gas.
According to some embodiments of the application of the present invention, the carbon nanotubes have an average wall number of 3 to 4, and belong to oligowalled carbon nanotubes.
According to some embodiments of the use of the present invention, the carbon nanotubes have a specific surface area of more than 600m2/g。
According to some embodiments of the application of the present invention, the carbon nanotubes have a specific surface area of 620m2/g～700m2/g。
According to some embodiments of the uses of the present invention, the carbon nanotubes have an IG/IDThe value is 0.87 to 0.99.
According to some embodiments of the application of the present invention, the carbon nanotubes are arrayed carbon nanotubes.
According to some embodiments of the uses of the invention, the carbon nanotubes are >40 times more powerful.
According to some embodiments of the application of the present invention, the rate of the carbon nanotubes is 45-70.
According to other embodiments of the application of the present invention, the rate of the carbon nanotubes is 47-61.
According to some embodiments of the use of the present invention, the carbon nanotubes are oligowall array carbon nanotubes.
According to some embodiments of the application of the present invention, the carbon nanotubes are carbon nanotubes with a catalyst, and the carbon source is catalyzed in a fluidized bed reactor to obtain the oligowalled array carbon nanotubes.
According to some embodiments of the application of the present invention, the time for preparing the carbon nanotube with the oligowall array by the catalytic carbon source is 30min to 60 min.
According to some embodiments of the application of the present invention, the time for preparing the carbon nanotube with the oligowall array by the catalytic carbon source is 30min to 50 min.
According to some embodiments of the application of the present invention, the temperature of the catalytic carbon source for preparing the carbon nanotubes with the oligowall array is 500-800 ℃.
According to some embodiments of the application of the present invention, the temperature of the catalytic carbon source for preparing the carbon nanotubes with the oligowall array is 600 ℃ to 800 ℃.
According to some embodiments of the application of the present invention, the growth rate of the oligowall array carbon nanotubes is 1.2g to 1.6g per minute per gram of the catalyst, i.e. 1.2gCNT/(gcat·min)～1.6gCNT/(gcat·min)。
The invention has the beneficial effects that:
the invention provides a porous flaky catalyst which is suitable for preparing a carbon nano tube, can meet the preparation requirement of a low-wall array carbon nano tube, can improve the growth rate of the carbon nano tube, improves the industrial production efficiency and has wide application prospect.
Specifically, compared with the prior art, the invention has the following advantages:
1) according to the invention, through the interaction of hydrogen bonds formed by the metal organic complex and the sheet template agent, the decomposition and deposition on the surface of the sheet template agent are realized, and the thickening agent is utilized to avoid the occurrence of sedimentation, so that the sheet catalyst with the active component particle size and distribution meeting the requirement of the growth of the oligoWA array carbon nanotube is obtained, the complex spray pyrolysis equipment is avoided, and the industrial production is facilitated.
2) The invention obtains the porous flaky catalyst, and the apparent density of the porous structure adjusting catalyst is 0.1g/cm3～0.5g/cm3Within the scope, the porous structure ensures the carbon tubeThe growth process has proper growth space.
3) The catalyst of the invention can be used for preparing the carbon nano tube by adopting the fluidization operation with high airspeed, can improve the growth rate of the carbon nano tube and improve the industrial production efficiency.
Drawings
FIG. 1 is an SEM photograph of a catalyst prepared in example 1 of the present invention;
FIG. 2 is an SEM image of carbon nanotubes of an array prepared in example 4 of the present invention;
FIG. 3 is an HRTEM image of the carbon nanotube array prepared in example 4 of the present invention;
FIG. 4 is an SEM image of arrayed carbon nanotubes of example 5 of the present invention;
FIG. 5 is an HRTEM image of arrayed carbon nanotubes prepared in example 5 of the present invention;
FIG. 6 is an SEM image of arrayed carbon nanotubes of example 6 of the present invention;
FIG. 7 is a HRTEM image of arrayed carbon nanotubes prepared in example 6 of the present invention;
FIG. 8 is an SEM image of carbon nanotubes of the array prepared in comparative example 3.
Detailed Description
The present invention will be described in further detail with reference to specific examples. The starting materials, reagents or apparatus used in the examples and comparative examples were obtained from conventional commercial sources or can be obtained by a method of the prior art, unless otherwise specified. Unless otherwise indicated, the testing or testing methods are conventional in the art.
Example 1
This example provides a method for preparing a catalyst, comprising the steps of:
step 1: dissolving ferric nitrate nonahydrate and cobalt nitrate hexahydrate (the total molar weight of the ferric nitrate nonahydrate and the cobalt nitrate hexahydrate is 0.5mol), 1.5mol of magnesium nitrate hexahydrate, 1.5mol of aluminum nitrate nonahydrate and ethylenediamine tetraacetic acid in water, stirring and dissolving at the temperature of 50-60 ℃, and stirring for 1h under the condition of heat preservation to form the metal-organic complex.
Step 2: to the solution in step 1 was added 0.22mol of flaky Al (OH)3Stirring for 2h at 50-60 ℃.
And step 3: and (3) adding a guar gum thickening agent into the dispersion liquid in the step (2), and continuously stirring for 2 hours at the temperature of between 50 and 60 ℃ to obtain a precursor dispersion liquid with the viscosity (25 ℃) of about 4000mPa s.
And 4, step 4: the precursor dispersion was calcined in a high temperature furnace at 450 ℃ and then pulverized into 50 to 200 mesh to obtain the catalyst of this example.
Example 2
This example provides a method for preparing a catalyst, comprising the steps of:
step 1: dissolving ferric nitrate nonahydrate and cobalt nitrate hexahydrate (the total molar weight of the ferric nitrate nonahydrate and the cobalt nitrate hexahydrate is 0.5mol), 1.0mol of magnesium nitrate hexahydrate, 1.3mol of aluminum nitrate nonahydrate and citric acid in water, stirring and dissolving at the temperature of 60-70 ℃, and then stirring for 1 hour under the condition of heat preservation to form the metal organic complex.
Step 2: to the solution in step 1 was added 1.4mol of Mg (OH) in the form of flakes2Stirring for 2h at 60-70 ℃.
And step 3: and (3) adding a guar gum thickening agent into the dispersion liquid in the step (2), and continuously stirring for 2 hours at the temperature of between 60 and 70 ℃ to obtain a precursor dispersion liquid with the viscosity (25 ℃) of about 2000mPa & s.
And 4, step 4: the precursor dispersion was calcined in a high temperature furnace at 500 ℃ and then pulverized into 50 to 200 mesh to obtain the catalyst of this example.
Example 3
This example provides a method for preparing a catalyst, comprising the steps of:
step 1: dissolving 0.8mol of magnesium nitrate hexahydrate, 0.8mol of aluminum nitrate nonahydrate and polyacrylic acid in water, stirring and dissolving at the temperature of 70-80 ℃, and stirring for 1h under the condition of heat preservation to form the metal-organic ligand complex.
Step 2: adding a flaky aluminum-magnesium hydrotalcite carrier (the mole number of Mg and Al is 2.1mol) into the solution in the step 1, and stirring for 2 hours at the temperature of 50-80 ℃.
And step 3: adding guar gum thickener into the dispersion liquid in the step 2, and continuously stirring for 2h at 70-80 ℃ to obtain a precursor dispersion liquid with the viscosity (25 ℃) of about 20000 mPas.
And 4, step 4: the precursor dispersion was calcined in a high temperature furnace at 500 ℃ and then pulverized into 50 to 200 mesh to obtain the catalyst of this example.
Comparative example 1
This example provides a method for preparing a catalyst, comprising the steps of:
step 1: dissolving ferric nitrate nonahydrate and cobalt nitrate hexahydrate (the total molar weight of the ferric nitrate nonahydrate and the cobalt nitrate hexahydrate is 0.5mol), 1.5mol of magnesium nitrate hexahydrate, 1.5mol of aluminum nitrate nonahydrate and ethylenediamine tetraacetic acid in water, stirring and dissolving at the temperature of 50-60 ℃, and stirring for 1h under the condition of heat preservation to form the metal-organic complex.
Step 2: to the solution in step 1 was added 0.11mol of flaky Al (OH)3Stirring for 2h at 50-60 ℃.
And step 3: and (3) adding a guar gum thickening agent into the dispersion liquid in the step (2), and continuously stirring for 2 hours at the temperature of between 50 and 60 ℃ to obtain a precursor dispersion liquid with the viscosity (25 ℃) of about 4000mPa s.
And 4, step 4: the precursor dispersion was calcined in a high temperature furnace at 450 ℃ and then pulverized into 50 to 200 mesh to obtain the catalyst of this example.
Comparative example 2
This example provides a method for preparing a catalyst, comprising the steps of:
step 1: dissolving 0.8mol of magnesium nitrate hexahydrate, 0.8mol of aluminum nitrate nonahydrate and polyacrylic acid in water, stirring and dissolving at the temperature of 50-80 ℃, and then stirring for 1h under heat preservation to form the metal organic complex.
Step 2: adding an aluminum-magnesium hydrotalcite carrier (the mole number of Mg and Al is 3.0mol) into the solution in the step 1, and stirring for 2 hours at the temperature of 50-80 ℃.
And step 3: adding guar gum thickener into the dispersion liquid in the step 2, and continuously stirring for 2h at 50-80 ℃ to obtain a precursor dispersion liquid with the viscosity (25 ℃) of about 20000 mPas.
And 4, step 4: the precursor dispersion was calcined in a high temperature furnace at 500 ℃ and then pulverized into 50 to 200 mesh to obtain the catalyst of this example.
Example 4
The present invention provides a method for preparing an oligowall array carbon nanotube, comprising the following steps:
the catalyst prepared in the example 1 is used for catalyzing ethylene to crack and grow the carbon nano tube in a fluidized bed reactor at the temperature of 600-800 ℃, and the growth time is 50 min.
Example 5
The present invention provides a method for preparing an oligowall array carbon nanotube, comprising the following steps:
the catalyst prepared in the embodiment 2 catalyzes ethylene to grow the carbon nano tube in a fluidized bed reactor at the temperature of 600-800 ℃, and the growth time is 40 min.
Example 6
The present invention provides a method for preparing an oligowall array carbon nanotube, comprising the following steps:
the catalyst prepared in the embodiment 3 catalyzes ethylene to grow the carbon nano tube in a fluidized bed reactor at the temperature of 600-800 ℃, and the growth time is 30 min.
Comparative example 3
The present invention provides a method for preparing an oligowall array carbon nanotube, comprising the following steps:
the catalyst prepared in the comparative example 1 catalyzes ethylene to grow the carbon nano tube in a fluidized bed reactor at the temperature of 600-800 ℃, and the growth time is 40 min.
Comparative example 4
The present invention provides a method for preparing an oligowall array carbon nanotube, comprising the following steps:
the catalyst prepared in the comparative example 2 catalyzes ethylene to grow the carbon nano tube in a fluidized bed reactor at the temperature of 600-800 ℃, and the growth time is 30 min.
The catalysts prepared in examples 1 to 3 and comparative examples 1 to 2 were subjected to an apparent density test, and the test results are shown in table 1.
Table 1 results of catalyst performance test of examples and comparative examples
Catalyst numbering Apparent density (g/cm) of catalyst3)
Example 1 0.13
Example 2 0.25
Example 3 0.47
Comparative example 1 0.11
Comparative example 2 0.59
FIG. 1 is an SEM (scanning Electron microscope) image of the catalyst prepared in example 1. As can be seen from fig. 1, the technical solution provided by the present invention can control the particle size of the active component, and the active component is uniformly distributed in the catalyst, and the obtained catalyst exhibits a porous sheet-like morphology.
I of multiplying power, specific surface area (static multipoint BET method) and Raman are carried out on the oligowall array carbon nano tubes prepared in examples 4 to 6 and comparative examples 3 to 4G/IDThe value (1570-1610 cm)-1The intensity of the G peak is 1320-1360 cm-1D peak intensity ratio) and the test results are shown in table 2.
Table 2 carbon nanotube performance test results of examples and comparative examples
Figure BDA0003021864740000091
Fig. 2 and 3 are SEM images and HRTEM (high resolution transmission electron microscope) images of the arrayed carbon nanotubes prepared in example 4, respectively. Fig. 4 and 5 are SEM and HRTEM images of the carbon nanotubes of example 5. Fig. 6 and 7 are SEM and HRTEM images of the arrayed carbon nanotubes prepared in example 6, respectively. FIG. 8 is an SEM image of the carbon nanotubes of comparative example 3.
As shown in Table 2 and FIGS. 2 to 8, the catalyst of the present invention can be used to grow oligo-walled carbon nanotubes (with an average wall number of 3 to 4) at a high speed (with a specific surface area of more than 600 m) by using a high space velocity process due to its high apparent density2/g), the multiplying power of the carbon tube obtained by the shortest reaction time of 30min is more than 40 times. In comparative example 3, since the amount of the sheet template added was too low, the carbon nanotubes grown using the catalyst of comparative example 1 were a mixture of array tubes and winding tubes; in comparative example 4, since the amount of the template added is too high, the specific gravity of the catalyst of comparative example 2 is large, and the yield of the obtained carbon tubes is remarkably reduced.
Further analyzing the growth rate and the graphitization degree of the embodiments 4-6 and the comparative example 3, the larger the apparent density of the catalyst is, the higher airspeed can be adopted for growth, so that the growth rate of the carbon tube is faster, and the defect increase of the carbon tube can not be caused, thereby reducing the graphitization degree; in comparative example 4, since the apparent density of the catalyst was too high and the same space velocity as in example 6 was used, the rate obtained was significantly reduced due to the limited growth space, and the defects of the carbon tubes were increased.
The test results show that the size and distribution of the active components can be effectively controlled by adopting the common high-temperature furnace pyrolysis catalyst precursor dispersion liquid without adopting a complex spray pyrolysis process, and finally the shape of the porous flaky catalyst is obtained. The above effects can be achieved for four reasons: 1) the metal ions and the polycarboxylic acid form a metal organic complex, and finally, the active component is uniformly dispersed in the inactive component in a small particle size; 2) thickening agent tabletThe metal organic complex is uniformly mixed with the template agent without sedimentation; 3) the metal organic ligand and the sheet template agent can form hydrogen bond action, so that the metal organic complex is subjected to surface decomposition deposition by taking the sheet carrier as a template; 4) gas generated by the decomposition of organic matters promotes the formation of a porous structure, and the apparent density of the catalyst is adjusted to be 0.1g/cm3～0.5g/cm3In the range, the porous structure ensures that a proper growth space exists in the carbon tube growth process, a fluidized bed process with high space velocity can be adopted for proper apparent density, and the multiplying power of the obtained carbon nano tube is more than 40 times within 30 min.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (13)

1. A catalyst, characterized by: the catalyst comprises a porous flaky carrier and an active component dispersed on the porous flaky carrier; the active component includes a transition metal element.
2. A catalyst according to claim 1, wherein: in the active component, the transition metal element comprises at least one of Fe, Co, Ni, Mo, Cu and Mn.
3. A catalyst according to claim 1 or 2, wherein: the apparent density of the catalyst was 0.1g/cm3～0.5g/cm3。
4. A catalyst according to claim 3, wherein: the catalyst is prepared from the following components: active component salt, inactive component salt, organic ligand, sheet-shaped template agent and thickening agent;
wherein the active ingredient salt comprises a transition metal salt; the inactive component salt comprises at least one of an Al salt and a Mg salt.
5. A catalyst according to claim 4, wherein: the flaky template comprises a flaky material containing at least one of Al and Mg.
6. A catalyst according to claim 4, wherein: the organic ligand comprises polycarboxylic acid, or polycarboxylic acid and polyamine.
7. A catalyst according to claim 4, wherein: the thickener comprises at least one of guar gum, polyacrylamide, carob bean gum, glucomannan, xanthan gum and collagen.
8. A catalyst according to claim 5, wherein: the molar ratio of metal atoms of the flaky template to the total metal atoms of the catalyst is (5-50): 100.
9. a catalyst according to claim 5, wherein: the mole number of the metal atoms in the active component is less than or equal to the total mole number of the metal atoms in the non-active component salt and the sheet template agent.
10. A process for preparing a catalyst as claimed in any one of claims 1 to 9, characterized in that: the method comprises the following steps:
1) mixing active component salt, inactive component salt and organic ligand in a solvent to obtain a metal organic complex solution;
2) mixing the metal organic complex solution with a flaky template agent to obtain a dispersion liquid;
3) mixing the dispersion liquid with a thickening agent to obtain a precursor dispersion liquid;
4) and calcining the precursor dispersion liquid to obtain the catalyst.
11. The method of manufacturing according to claim 10, wherein: the viscosity of the precursor dispersion liquid at 25 ℃ is 1000mPa & s to 100000mPa & s.
12. The method of manufacturing according to claim 10, wherein: in the step 4), the calcining temperature is 300-600 ℃.
13. The application of the catalyst in the preparation of the carbon nano tube is characterized in that: the catalyst is the catalyst as described in any one of claims 1 to 9, or is prepared by the preparation method as described in any one of claims 10 to 12.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114515578A (en) * 2021-12-31 2022-05-20 佛山市格瑞芬新能源有限公司 Catalyst for preparing carbon nano tube and preparation method and application thereof
CN114570380A (en) * 2022-02-28 2022-06-03 诺瑞(深圳)新技术有限公司 Catalyst for growing ultrahigh specific surface area and few-wall carbon nano-tube and application thereof
CN115041180A (en) * 2022-06-24 2022-09-13 深圳烯湾科技有限公司 Carbon nanotube catalyst, preparation method thereof and carbon nanotube fluidized bed preparation process
CN115672345A (en) * 2022-10-27 2023-02-03 深圳市飞墨科技有限公司 Preparation method of single-walled carbon nanotube catalyst
CN115806287A (en) * 2021-09-15 2023-03-17 江苏天奈科技股份有限公司 Array carbon nanotube and method for preparing array carbon nanotube and lamellar catalyst

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115806287A (en) * 2021-09-15 2023-03-17 江苏天奈科技股份有限公司 Array carbon nanotube and method for preparing array carbon nanotube and lamellar catalyst
CN114515578A (en) * 2021-12-31 2022-05-20 佛山市格瑞芬新能源有限公司 Catalyst for preparing carbon nano tube and preparation method and application thereof
CN114570380A (en) * 2022-02-28 2022-06-03 诺瑞(深圳)新技术有限公司 Catalyst for growing ultrahigh specific surface area and few-wall carbon nano-tube and application thereof
CN115041180A (en) * 2022-06-24 2022-09-13 深圳烯湾科技有限公司 Carbon nanotube catalyst, preparation method thereof and carbon nanotube fluidized bed preparation process
CN115672345A (en) * 2022-10-27 2023-02-03 深圳市飞墨科技有限公司 Preparation method of single-walled carbon nanotube catalyst
CN115672345B (en) * 2022-10-27 2023-12-15 深圳市飞墨科技有限公司 Preparation method of single-walled carbon nanotube catalyst

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