Disclosure of Invention
Based on the above, the invention provides a device and a method for preparing multi-wall high-purity carbon nanotube fibers, which aim to solve the technical problem that the carbon nanotube fibers cannot be continuously prepared by using biomass as a carbon source in the prior art.
In order to achieve the above objects, the present invention provides an apparatus for preparing a multi-wall high-purity carbon nanotube fiber, comprising:
the feeding mechanism is used for providing a precursor solution for preparing the multi-wall high-purity carbon nanotube fibers;
a carrier gas source for providing a carrier gas flow;
the vaporizing chamber is connected with the feeding mechanism and the carrier gas source and is used for receiving the precursor liquid provided by the feeding mechanism and the carrier gas flow provided by the carrier gas source and providing high temperature to ensure that the precursor liquid is dispersed at high temperature to form a water vapor state;
the ionization box is connected with the discharge side of the vaporization chamber, precursor liquid in a water vapor state formed in the vaporization chamber is brought into the ionization box by carrier gas flow, the ionization box is used for providing high-energy electron beams to impact the precursor liquid in the water vapor state, and the ionization box is provided with an ionization source for generating the high-energy electron beams;
the device comprises an ionization box, a corundum tube, a gas-carrying gas flow and a gas-carrying gas flow, wherein the ionization box is internally provided with a precursor liquid impacted by a high-energy electron beam and is brought into the corundum tube by the gas-carrying gas flow;
the corundum tube is arranged in a hearth of the horizontal reaction furnace in a penetrating manner and is used for providing high temperature required by the corundum tube; and
and the cooling material receiving mechanism is arranged on the discharge side of the corundum tube, the carbon nanotube aerogel in the corundum tube is driven by carrier gas flow to gush out, and the cooling material receiving mechanism is used for cooling the gushed carbon nanotube aerogel in a water bath to enable the gushed carbon nanotube aerogel to shrink into carbon nanotube fibers and simultaneously mechanically winding and collecting the carbon nanotube fibers.
As a further preferable technical scheme of the invention, the feeding mechanism is a peristaltic pump, and the carrier gas source is a gas cylinder filled with inert gas.
In a further preferred embodiment of the present invention, the horizontal reactor has different heating temperatures for the section a and the section B, and the horizontal reactor has a temperature setter for controlling the heating temperature of the horizontal reactor.
As a further preferable technical scheme of the invention, the cooling and material receiving mechanism comprises a water tank, a godet roller, a material receiving roller and a motor, the water tank is arranged on the discharge side of the corundum tube, the godet roller is arranged in the water tank, the material receiving roller is arranged outside the water tank and is driven by the motor to rotate, the water tank is used for carrying out water bath cooling on the carbon nanotube aerogel so as to generate carbon nanotube fibers, and the material receiving roller is used for winding and collecting the carbon nanotube fibers passing through the godet roller under the driving of the motor.
According to another aspect of the present invention, the present invention also provides a method for preparing a multi-walled high purity carbon nanotube fiber using any one of the above apparatus, comprising the steps of:
dissolving a carbon source, a catalyst and an accelerant in a solvent to obtain a precursor solution, wherein the mass percent of each component is as follows: 1-2.5% of carbon source, 0.3-1.2% of catalyst, 0.2-1.5% of accelerant and 95-97.6% of solvent, wherein the carbon source is biomass from which alkali metal is removed after alcohol washing;
feeding the precursor liquid into a vaporization chamber through a feeding mechanism, simultaneously providing carrier gas flow for the vaporization chamber by a carrier gas source, and providing high temperature for the vaporization chamber to disperse the precursor liquid to form a water vapor state;
the water vapor precursor liquid enters the ionization box under the driving of carrier gas flow, and the ionization box provides high-energy electron beams to impact the precursor liquid to cause the breakage of chemical bonds or the molecular rearrangement of the precursor liquid to form fragments;
the precursor liquid which forms a chip shape enters the corundum tube under the driving of carrier gas flow, the corundum tube is heated by a horizontal reaction furnace, the precursor liquid is firstly cracked into white aerogel fog cluster in the tube section A of the corundum tube, then carbon nano tubes grow in the tube section B of the corundum tube, and the carbon nano tubes are contacted with each other to further form black semitransparent cylindrical carbon nano tube aerogel;
the carbon nanotube aerogel gushes out from the corundum tube to the water tank under the action of carrier gas flow, and is cooled in water bath to generate carbon nanotube fibers, and the carbon nanotube fibers are mechanically collected through a cooling material receiving mechanism.
As a further preferable technical scheme of the invention, the biomass is tannic acid, gallic acid or quercetin rich in hydroxyl, the catalyst is ferrocene, cobaltocene, nickelocene, ferric chloride, ferric sulfide or nickel oxalate, and the accelerator is thiophene, water, hydrogen sulfide or carbon disulfide.
In a further preferred embodiment of the present invention, the solution for washing the carbon source with alcohol is methanol, ethanol or a mixed alcohol solution.
As a further preferable technical scheme of the invention, the liquid inlet quantity of the feeding mechanism is 1-5ml/min, and the speed of the carrier gas flow is 10-120 sccm.
As a further preferable technical scheme of the invention, the cracking temperature in the section A of the corundum tube is 400-1500 ℃, and the temperature for generating the carbon nano tube aerogel in the section B of the corundum tube is 1200-1500 ℃.
As a further preferable technical scheme of the invention, the cooling material receiving mechanism comprises a water tank, a godet roller, a material receiving roller and a motor, wherein the material receiving roller is used for winding and collecting the carbon nanotube fibers passing through the godet roller under the driving of the motor, and the speed of the motor driving the godet roller to perform mechanical collection is 2-8 m/min.
By adopting the technical scheme, the device and the method for preparing the multi-wall high-purity carbon nanotube fiber can achieve the following beneficial effects:
1) the biomass is used as a carbon source, the cracking direction can be accurately controlled, CO and CH4 gas for effectively synthesizing the carbon nano tube is generated, H2O is generated by cracking, water-coal-gas reaction is generated, the proportion of amorphous carbon is reduced, and therefore continuous preparation of the carbon nano tube fiber is realized;
2) the ionization box provided by the invention provides the precursor liquid in a high-energy electron beam impact water vapor state, so that chemical bonds are broken or molecules are rearranged, various ions are generated instantly, and biomass is used as a carbon source to prepare the multi-wall high-purity carbon nanotube fiber, so that the precursor liquid can form the carbon nanotube under the action of a catalyst, the inactivation of the catalyst caused by the formation of coke is avoided, and the continuous preparation of the carbon nanotube is ensured;
3) the carbon source of the carbon nanotube fiber prepared by the device and the method can be green and regenerated, the natural content is rich, the raw materials are easy to obtain, and the production cost is low; and has the effects of high graphitization degree and high purity.
Detailed Description
The invention will be further described with reference to the accompanying drawings and specific embodiments. In the preferred embodiments, the terms "upper", "lower", "left", "right", "middle" and "a" are used for clarity of description only, and are not used to limit the scope of the invention, and the relative relationship between the terms and the terms is not changed or modified substantially without changing the technical content of the invention.
As shown in fig. 1, the present invention provides an apparatus for preparing multi-wall high-purity carbon nanotube fiber, comprising a peristaltic pump, a vaporization chamber, an ionization box, a corundum tube, a horizontal reaction furnace, a carrier gas source, a water tank, a godet roller, a material receiving roller and a motor, wherein:
the peristaltic pump is used for providing precursor liquid for preparing the multi-wall high-purity carbon nanotube fiber to the vaporization chamber;
the carrier gas source is used for providing carrier gas flow to the vaporization chamber, the carrier gas is inert gas such as hydrogen, argon, nitrogen or helium, and the carrier gas source can be a gas cylinder;
the vaporization chamber is connected to the discharge side of the steam peristaltic pump and is used for providing high temperature to enable the precursor liquid to be dispersed at the high temperature to form a water vapor state;
the ionization box is connected to the discharge side of the vaporization chamber, precursor liquid in a water vapor state formed in the vaporization chamber is brought into the ionization box by carrier gas flow, the ionization box is used for providing high-energy electron beams to impact the precursor liquid in the water vapor state, and the ionization box is provided with an ionization source for generating the high-energy electron beams;
the corundum tube is connected to the discharge side of the ionization box, precursor liquid impacted by high-energy electron beams in the ionization box is brought into the corundum tube by carrier gas flow, the corundum tube is used for enabling the precursor liquid impacted by the high-energy electron beams to form black semi-transparent cylindrical carbon nanotube aerogel at high temperature, and the corundum tube penetrates through and is arranged in a hearth of the horizontal reaction furnace to provide high temperature required by the corundum tube; in specific implementation, the corundum tube is sequentially divided into a tube section A and a tube section B along the precursor liquid transmission direction;
the water tank sets up the discharge side of corundum pipe, the intraductal carbon nanotube aerogel of corundum drives by the carrier gas air current and gushes out, and the godet roller sets up in the water tank, receive the material roller setting and be in the water tank outer and by the motor drives rotatoryly, the water tank is used for carrying out the water bath cooling to the carbon nanotube aerogel who gushes out in order to generate carbon nanotube fibre, it is used for passing through to receive the material roller under the drive of motor the carbon nanotube fibre of godet roller twines and collects.
In specific implementation, the horizontal reaction furnace has different heating temperatures for the section A and the section B, and the horizontal reaction furnace is provided with a temperature setter for controlling the heating temperature of the horizontal reaction furnace.
The invention also provides a method for preparing the multi-wall high-purity carbon nanotube fiber, which comprises the following steps:
step S1, dissolving a carbon source, a catalyst and an accelerant in a solvent to obtain a precursor solution, wherein the mass percentage of each component is as follows: 1-2.5% of carbon source, 0.3-1.2% of catalyst, 0.2-1.5% of accelerant and 95-97.6% of solvent, wherein the carbon source is biomass from which alkali metal is removed after alcohol washing;
step S2, feeding the precursor liquid into a vaporization chamber from a feeding mechanism, simultaneously, providing carrier gas flow to the vaporization chamber by a carrier gas source, and providing high temperature for the vaporization chamber to disperse the precursor liquid to form a water vapor state;
step S3, the precursor liquid in the water vapor state enters an ionization box under the drive of carrier gas flow, the ionization box provides high-energy electron beams to impact the precursor liquid, and chemical bonds of the precursor liquid are broken or molecules are rearranged to form fragments;
step S4, enabling the precursor liquid in a chip form to enter a corundum tube under the drive of carrier gas flow, heating the corundum tube by a horizontal reaction furnace, cracking the precursor liquid into white aerogel-like fogged in a tube section A of the corundum tube, growing carbon nano tubes in a tube section B of the corundum tube, and further enabling the carbon nano tubes to be in contact with each other to form black semi-transparent cylindrical carbon nano tube aerogel;
and step S5, the carbon nanotube aerogel gushes out of the corundum tube to a water tank under the action of carrier gas flow, carbon nanotube fibers are generated through water bath cooling, and the carbon nanotube fibers are mechanically collected through a cooling material receiving mechanism.
The biomass is preferably hydroxyl-rich tannic acid, gallic acid or quercetin, the catalyst is ferrocene, cobaltocene, nickelocene, ferric chloride, ferric sulfide or nickel oxalate, and the accelerator is thiophene, water, hydrogen sulfide or carbon disulfide.
Before step S1, the carbon source may be subjected to alcohol washing, and the solution for the alcohol washing of the carbon source may be methanol, ethanol or mixed alcohol solution.
In the specific implementation, the liquid inlet amount of the feeding mechanism is 1-5ml/min, the speed of the carrier gas flow is 10-120sccm, the cracking temperature in the pipe section A of the corundum pipe is 400-1500-.
According to the invention, the multi-wall high-purity carbon nanotube fiber is prepared by adopting the device for preparing the multi-wall high-purity carbon nanotube fiber, so that the preparation method is simple, easy to implement and strong in applicability, and the prepared carbon nanotube fiber has good use performance, can be widely used as a working electrode and applied to the fields of energy recovery and sewage treatment catalysis; moreover, the carbon source for preparing the carbon nanotube fiber is green and renewable, the natural content is rich, and the raw materials are easy to obtain. Referring to fig. 2, by using biomass as a carbon source, the cracking direction can be precisely controlled, CO and CH4 gas for effectively synthesizing carbon nanotubes are generated, H2O is generated by cracking, a water-coal-steam reaction occurs, the proportion of amorphous carbon is reduced, and continuous preparation of carbon nanotube fibers is realized.
The carbon nanotube fiber prepared by the preparation method has the diameter of the carbon nanotube of 10-30nm, the I (D)/I (G) of 4.1-6.5, the wall layer of the carbon nanotube of 5-10, the diameter of the carbon nanotube fiber of 25-50 μm, the mechanics of the carbon nanotube fiber of 960MPa-2GPa, the electrical conductivity of the carbon nanotube fiber of 2 x 105S/m2-5 x 105S/m2 and the C atom ratio of more than 80 percent. The relevant properties of the carbon nanotube fibers prepared by the present invention are shown in fig. 3-7: fig. 3 is a fiber arrangement diagram in the carbon nanotube fiber, which is advantageous for improving the mechanical properties due to the directional arrangement of the carbon nanotubes under the transportation action of the carrier gas flow. The carbon nanotube fiber can reduce the gap between the carbon nanotubes by twisting treatment, the cross-sectional shape of the fiber is changed from a belt shape to a circular shape, so that the mechanical strength and the use performance can be improved, the figure 4 is a shape chart of the carbon nanotube fiber, and the carbon nanotube fiber is twisted to have uniform fiber thickness and diameter of 20 +/-4 mu m. FIG. 5 is a Raman spectrum of carbon nanotube fiber, wherein the peak D represents the defect degree of carbon nanotubes, the peak G represents the graphitization degree of carbon nanotubes, and the peak 2D represents the wall thickness of carbon nanotubes, it can be seen that I (G)/I (D) is greater than 2, the graphitization degree of carbon nanotubes is higher, I (G)/I (2D) is greater than 1, and the wall layers of carbon nanotubes are mainly multi-layered carbon nanotubes. FIG. 6 is a graph showing the content of carbon nanotube fiber elements, which mainly contain C, O, Fe, and S, and the content of C exceeds 80wt%, indicating that the prepared carbon nanotube fiber has pure characteristics. FIG. 7 is a transmission electron microscope image of carbon nanotubes, which shows that the carbon nanotubes have regular morphology, diameters of about 21 μm, and 8 layers of wall layers, and the analysis is consistent with the morphology, Raman spectrum and elemental map analysis of the carbon nanotube fibers.
In order to make the technical solution of the present invention better understood and realized by those skilled in the art, the preparation method of the present invention is further described in detail below in the form of specific examples.
Example 1
The carbon nanotube fiber is prepared by the device shown in figure 1, the precursor liquid is input by a peristaltic pump, a corundum tube is used as a high-temperature reactor, tannic acid is used as a carbon source, ferrocene is used as a catalyst, thiophene is used as an accelerant, and argon is used as a carrier gas.
Dispersing 2g of tannic acid, 0.50g of ferrocene and 0.90g of thiophene in 50ml of methanol solvent, preparing a precursor solution by ultrasonic dispersion and mixing, introducing the precursor solution into a vaporization chamber by using a peristaltic pump at the liquid inlet amount of 3ml/min, introducing argon into the vaporization chamber at the gas flow rate of 80sccp, and adjusting the furnace temperature of the horizontal reaction furnace to 1400 ℃. Precursor liquid entering a vaporization chamber through a peristaltic pump is vaporized, then is impacted by high-energy electron beams in an ionization box to cause the breakage of chemical bonds or molecular rearrangement, various ions are generated instantly, then polyhydroxy biomass is cracked into micromolecular gas CO under the action of a catalyst in a corundum tube in an accelerating way, the catalyst is sublimated in a high-temperature area section of the corundum tube and is pyrolyzed with an accelerant to form a new carbon nano tube nucleation point, the gas cracked by the biomass grows into a carbon nano tube on the surface of the nucleation point and is deposited to form black semitransparent cylindrical carbon nano tube aerogel, and at the moment, the carbon nano tube aerogel is enabled to be gushed out from the tail end in the corundum tube under the driving of argon gas flow.
The carbon nanotube aerogel entering the atmosphere is cooled and contracted into carbon nanotube fibers by a water tank, and then the fibers are wound on a yarn winding roller and collected into yarns by mechanical winding.
The obtained carbon nanotube fiber was analyzed by tests, and the fiber diameter was 37 μm, the mechanical strength of the fiber was 1.8GPa, the carbon element proportion in the fiber was 82%, the graphitization degree i (g)/i (d) =6.0, and the number of carbon nanotube walls was 8.
Example 2
The carbon nanotube fiber is prepared by the device shown in figure 1, the precursor liquid is input by a peristaltic pump, a corundum tube is used as a high-temperature reactor, gallic acid is used as a carbon source, ferrocene is used as a catalyst, thiophene is used as an accelerant, and argon is used as a carrier gas.
Dispersing 2.5g of gallic acid, 0.50g of ferrocene and 0.90g of thiophene in 50ml of methanol solvent, preparing a precursor solution by ultrasonic dispersion and mixing, introducing the precursor solution into a vaporization chamber by using a peristaltic pump at the liquid inlet amount of 3ml/min, introducing argon at the gas flow rate of 60sccp, and adjusting the furnace temperature of the horizontal reaction furnace to 1400 ℃. Precursor liquid entering a vaporization chamber through a peristaltic pump is vaporized, then is impacted by high-energy electron beams in an ionization box to cause the breakage of chemical bonds or molecular rearrangement, various ions are generated instantly, then polyhydroxy biomass is cracked into micromolecular gas CO under the action of a catalyst in a corundum tube in an accelerating way, the catalyst is sublimated in a high-temperature area section of the corundum tube and is pyrolyzed with an accelerant to form a new carbon nano tube nucleation point, the gas cracked by the biomass grows into a carbon nano tube on the surface of the nucleation point and is deposited to form black semitransparent cylindrical carbon nano tube aerogel, and at the moment, the carbon nano tube aerogel is enabled to flow out from the tail end in the corundum tube under the driving of argon gas flow.
The carbon nanotube aerogel entering the atmosphere is cooled and contracted into carbon nanotube fibers by a water tank, and then the fibers are wound on a yarn winding roller and collected into yarns by mechanical winding.
According to test analysis of the obtained carbon nanotube fiber, the diameter of the fiber is 30 μm, the strength of the fiber is 1.5GPa, the proportion of carbon elements in the fiber is 86%, the graphitization degree I (G)/I (D) =5.8, and the number of the wall layers of the carbon nanotube is 8.
Example 3
The carbon nanotube fiber is prepared by the device shown in figure 1, the precursor liquid is input by a peristaltic pump, a corundum tube is used as a high-temperature reactor, quercetin is used as a carbon source, ferrocene is used as a catalyst, thiophene is used as an accelerant, and argon is used as a carrier gas.
Dispersing 1.5g of quercetin, 0.50g of ferrocene and 0.90g of thiophene in 50ml of methanol, preparing a precursor solution by ultrasonic dispersion and mixing, introducing the precursor solution into a vaporization chamber by using a peristaltic pump at the liquid inlet amount of 3ml/min, introducing argon at the gas flow rate of 100sccp, and adjusting the furnace temperature of the horizontal reaction furnace to 1400 ℃. Precursor liquid entering a vaporization chamber through a peristaltic pump is vaporized, then is impacted by high-energy electron beams in an ionization box to cause the breakage of chemical bonds or molecular rearrangement, various ions are generated instantly, then polyhydroxy biomass is cracked into micromolecular gas CO under the action of a catalyst in a corundum tube in an accelerating way, the catalyst is sublimated in a high-temperature area section of the corundum tube and is pyrolyzed with an accelerant to form a new carbon nano tube nucleation point, the gas cracked by the biomass grows into a carbon nano tube on the surface of the nucleation point and is deposited to form black semitransparent cylindrical carbon nano tube aerogel, and at the moment, the carbon nano tube aerogel is enabled to flow out from the tail end in the corundum tube under the driving of argon gas flow.
The carbon nanotube aerogel entering the atmosphere is cooled and contracted into carbon nanotube fibers by a water tank, and then the fibers are wound on a yarn winding roller and collected into yarns by mechanical winding.
According to test analysis of the obtained carbon nanotube fiber, the diameter of the fiber is 42 μm, the mechanical strength of the fiber is 1.1GPa, the proportion of carbon elements in the fiber is 83%, the graphitization degree I (G)/I (D) =4.9, and the number of the wall layers of the carbon nanotube is 11.
Comparative example 1
In order to verify the influence of equipment on the preparation of the carbon nanotube fibers, the ionization box function is not started in the comparative example, namely, an ionization source generating high-energy electron beams is not generated, the high-energy electron beams do not provide precursor liquid for impacting water vapor, the ionization box is provided with the precursor liquid which is input by a peristaltic pump, a corundum tube is used as a high-temperature reactor, tannic acid is used as a carbon source, ferrocene is used as a catalyst, thiophene is used as an accelerator, and argon is used as a carrier gas.
Dispersing 2g of tannic acid, 0.50g of ferrocene and 0.90g of thiophene in 50ml of methanol, ultrasonically dispersing and mixing to prepare a precursor solution, introducing the precursor solution into a vaporization chamber by using a peristaltic pump at a liquid inlet amount of 3ml/min, introducing argon at a gas flow rate of 80sccp, adjusting the furnace temperature of a horizontal reaction furnace to 1400 ℃, vaporizing the precursor solution entering a quartz tube through the peristaltic pump, then accelerating cracking of polyhydroxy biomass in the corundum tube into micromolecular gas CO under the action of a catalyst, subliming the catalyst into a high-temperature region and pyrolyzing the catalyst to form a new carbon nanotube nucleation point, growing the gas cracked by the biomass into carbon nanotubes on the surface of the nucleation point, depositing to form black semi-transparent cylindrical carbon nanotube aerogel, and moving the carbon nanotube aerogel to the tail end of the corundum tube under the drive of argon gas flow.
The carbon nanotube aerogel entering the atmosphere is cooled and contracted into carbon nanotube fibers by a water tank, and then the fibers are wound on a yarn winding roller and collected into yarns by mechanical winding.
The obtained carbon nanotube fiber is analyzed by tests, and a large amount of black smoke is generated at the beginning, and then carbon nanotube aerogel is formed in the corundum tube, but the carbon nanotube aerogel cannot be continuous and black solid coke exists at the front end of the corundum tube. Therefore, the vaporized precursor liquid is impacted by a high-energy electron beam to cause the breakage of chemical bonds or molecular rearrangement, and various ions are generated instantly, the key of the method for preparing the multi-wall high-purity carbon nanotube fiber by using biomass as a carbon source is used in the process, so that the carbon nanotube can be formed by the precursor liquid under the action of a catalyst, and the catalyst is prevented from being inactivated due to the formation of coke.
The following conclusions can be drawn from the combined analysis of examples 1 to 3, and comparative example 1:
1. the biomass is used as a carbon source and is used as a raw material for continuously preparing the carbon nanotube fiber, so that the problem that the carbon nanotube fiber cannot be continuously prepared by using the biomass as the carbon source at present is solved;
2. from the results of examples 1-3, it can be seen that the carbon nanotube fiber prepared by the method has the characteristics of high graphitization degree and high purity;
3. from the results of examples 1-3 and comparative example 1, it can be seen that the carbon source is mainly biomass, and the production cost is reduced compared with the conventional preparation process by forming carbon nanotube fibers from the carbon source in one step;
4. it can be known from comparative example 1 that the improvement of the preparation process is also an important measure for solving the problem of continuously preparing carbon nanotube fibers by using biomass as a carbon source, and the conclusion of the comparative example 1 proves that when biomass is used as a carbon source, high-energy electron beams are required to impact vaporized precursor liquid so as to improve the uniform dispersion degree of ionization, so that the continuous carbon nanotube fibers can be successfully prepared.
Although specific embodiments of the present invention have been described above, it will be appreciated by those skilled in the art that these are merely examples and that many variations or modifications may be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims.