Low-temperature carbon nanotube catalyst, and preparation method and application thereof

Abstract

This invention relates to a low-temperature carbon nanotube catalyst, its preparation method, and its application. The method includes: immersing alkali-free glass fibers in an acidified H₂O₂ solution, controlling the pH to 4-5, followed by reaction and washing to obtain activated alkali-free glass fibers; adjusting the pH of a 3-aminopropyltriethoxysilane / anhydrous ethanol solution to 4-5, stirring at room temperature to induce a hydrolysis reaction; immersing the activated alkali-free glass fibers in the solution to induce a condensation reaction; washing the alkali-free glass fibers to neutrality to obtain amino-modified alkali-free glass fibers; adding the amino-modified alkali-free glass fibers to an ethylene glycol mixed solution of iron acetylacetonate, cobalt acetylacetonate, and molybdenum hexacarbonyl, then adding sodium borohydride, stirring the mixture until homogeneous, and then reducing, filtering, washing, and drying to solidify. This invention reduces the erosion of the glass fiber surface by the catalyst metal during heat treatment by loading a low-temperature carbon nanotube catalyst onto the surface of the alkali-free glass fibers.

Description

Technical Field

[0001] This invention relates to a low-temperature carbon nanotube catalyst, its preparation method, and its application, belonging to the field of catalyst technology. Background Technology

[0002] Alkali-free glass fiber currently constitutes the largest segment of the glass fiber industry. It possesses high insulation, high heat resistance, and good mechanical strength, and its manufacturing process is mature and relatively inexpensive, making it commonly used in the manufacture of various composite materials. However, it also faces challenges such as limited functionality and poor interfacial compatibility in composite materials, posing significant challenges to its future development. Carbon nanotubes (CNTs), as a novel nanomaterial, possess unique physical, chemical, and mechanical properties and are considered excellent functional modifiers for traditional fiber materials. Recent studies have shown that in-situ growth of carbon nanotubes on the surface of alkali-free glass fiber using chemical vapor deposition can significantly improve the fiber's mechanical properties and endow it with electromagnetic functionalities. However, the growth of carbon nanotubes using chemical vapor deposition is usually carried out under the catalysis of metals such as Fe and Ni. These metal catalysts are not suitable for growth on the surface of alkali-free glass fibers, mainly for the following two reasons: First, the catalytic temperature is too high. Fe, Ni or their alloys usually need to be at 700℃ to 1000℃ to have the ability to catalyze the growth of carbon nanotubes, which is far beyond the softening point of alkali-free glass (~550℃), which will inevitably damage the fiber strength. Second, Fe will react with components such as SiO2 in alkali-free glass at high temperatures to generate compounds such as FeSiO3, which will destroy the original crystal lattice structure inside the alkali-free glass, induce crystal defects, and thus cause fiber embrittlement.

[0003] To achieve in-situ carbon nanotube modification on the surface of alkali-free glass fiber, it is necessary to develop novel carbon nanotube catalysts. These catalysts should have low-temperature (<550℃) catalytic effects and should not easily react with alkali-free glass components. Their design and preparation present significant challenges. Summary of the Invention

[0004] In view of this, the main objective of the present invention is to provide a low-temperature carbon nanotube catalyst, its preparation method and application. The problem to be solved is to reduce the erosion of the glass fiber surface by the catalyst metal during heat treatment and improve its catalytic efficiency at low temperature by loading a low-temperature carbon nanotube catalyst on the surface of alkali-free glass fiber, thereby ensuring that the mechanical properties of the fiber are not lost as much as possible before and after CNT growth.

[0005] The objective of this invention and the technical problem it solves are achieved through the following technical solution. This invention proposes a method for preparing a low-temperature carbon nanotube catalyst, comprising the following steps:

[0006] S1 fiber pretreatment: Immerse alkali-free glass fiber in hydrochloric acid-acidified H2O2 solution and control the pH value between 4 and 5. After reaction and washing, activated alkali-free glass fiber is obtained.

[0007] S2 3-aminopropyltriethoxysilane modification: The pH of the 3-aminopropyltriethoxysilane / anhydrous ethanol solution was adjusted to between 4 and 5, and the mixture was stirred at room temperature, resulting in the following hydrolysis reaction:

[0008] Si(OC2H5)3C(CH2)3NH2+3H2O→Si(OH)3C(CH2)3NH2+3C2H5OH;

[0009] The activated alkali-free glass fiber obtained in step S1 is then immersed in the solution, allowing the hydrolysis product of 3-aminopropyltriethoxysilane to undergo the following condensation reaction with the hydroxyl groups on the surface of the alkali-free glass fiber:

[0010] Si(OH)3C(CH2)3NH2+Si-OH→Si-O-Si(CH2)3NH2+H2O;

[0011] After the reaction is complete, the alkali-free glass fiber is washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber.

[0012] S3 Hydrothermal Deposition and Solidification: The amino-modified alkali-free glass fiber obtained in step S2 is added to a ethylene glycol mixed solution of iron acetylacetone, cobalt acetylacetone, and molybdenum hexacarbonyl, and then 0.1-0.5 mol of sodium borohydride is added. The mixture is stirred evenly and reduced to obtain alloy particles deposited on the surface of the alkali-free glass fiber. The alkali-free glass fiber is filtered, washed with anhydrous ethanol, and then dried and solidified to obtain alkali-free glass fiber carrying a low-temperature catalyst, which is the low-temperature carbon nanotube catalyst.

[0013] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0014] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, the concentration of the H2O2 solution in step S1 is 15wt% to 30wt%.

[0015] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S1, the reaction temperature is 40–60°C and the reaction time is 5–10 min.

[0016] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, the concentration of the 3-aminopropyltriethoxysilane / anhydrous ethanol solution in step S2 is 0.5 wt% to 8 wt%.

[0017] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, the stirring time at room temperature in step S2 is 0.5 to 2 hours.

[0018] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S2, the temperature of the condensation reaction is 40–80°C and the time is 0.5–2 h.

[0019] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S3, the concentration of iron acetylacetone in the ethylene glycol mixed solution of iron acetylacetone, cobalt acetylacetone, and molybdenum hexacarbonyl is 0.03–0.053 mol / L, the concentration of cobalt acetylacetone is 0.01–0.018 mol / L, and the concentration of molybdenum hexacarbonyl is 0.002–0.03 mol / L.

[0020] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S3, the proportion of molybdenum in the ethylene glycol mixed solution of iron acetylacetonate, cobalt acetylacetonate, and molybdenum hexacarbonyl is 5% to 30%, and the ratio of iron to cobalt is 3:1.

[0021] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S3, the reduction temperature is 80–120°C and the reduction time is 1–2 h.

[0022] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S3, the drying and curing temperature is 100–150°C, and the drying time is 5–10 min.

[0023] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S3, the molar percentage of molybdenum in the alkali-free glass fiber of the low-temperature catalyst is 0.05 to 0.3.

[0024] Preferably, in the aforementioned method for preparing low-temperature carbon nanotube catalysts, in step S3, the content of carbon nanotubes in the alkali-free glass fiber of the low-temperature catalyst is 10-30 wt%.

[0025] The objective of this invention and the technical problem it solves are achieved through the following technical solution. This invention proposes a low-temperature carbon nanotube catalyst, wherein the low-temperature carbon nanotube catalyst is supported on the surface of alkali-free glass fiber.

[0026] The objectives of this invention and the technical problems it addresses can be further achieved by the following technical measures.

[0027] Preferably, the aforementioned low-temperature carbon nanotube catalyst is prepared by the method described above.

[0028] The objective of this invention and the technical problem it solves are achieved through the following technical solution: The application of the aforementioned low-temperature carbon nanotube catalyst in chemical vapor deposition.

[0029] By employing the above technical solution, the low-temperature carbon nanotube catalyst, its preparation method, and its application provided by the present invention have at least the following advantages:

[0030] This invention proposes a low-temperature catalyst suitable for growing carbon nanotubes on the surface of alkali-free glass fibers. This catalyst can catalyze the growth of carbon nanotubes at temperatures below the softening point of glass fibers and has low corrosive effect on the fiber body, which is beneficial to maintaining the strength of the fiber body.

[0031] The catalyst proposed in this invention has mild preparation conditions, does not involve complex reactions such as high temperature and high pressure, causes low fiber damage, and is easy to synthesize in batches.

[0032] The catalyst proposed in this invention is applicable to conventional chemical vapor deposition methods, does not require complex equipment such as PECVD, has low equipment requirements, and is suitable for large-scale preparation methods.

[0033] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Attached Figure Description

[0034] Figure 1 This is a scanning electron microscope image of carbon nanotubes grown in Example 1 of the present invention;

[0035] Figure 2 This is a scanning electron microscope image of carbon nanotubes grown in Example 3 of the present invention;

[0036] Figure 3 This is a scanning electron microscope image of carbon nanotubes grown in Example 4 of the present invention;

[0037] Figure 4 This is a scanning electron microscope image of carbon nanotubes grown in Example 12 of the present invention. Detailed Implementation

[0038] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following detailed description, in conjunction with preferred embodiments, provides a detailed explanation of the specific implementation methods, structure, features, and effects of a low-temperature carbon nanotube catalyst, its preparation method, and its application according to the present invention. In the following description, different "embodiments" or "embodiments" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0039] Unless otherwise specified, all materials or reagents listed below are commercially available.

[0040] Some embodiments of the present invention provide a method for preparing a low-temperature carbon nanotube catalyst, comprising the following steps:

[0041] S1 Fiber Pretreatment: Take an appropriate amount of alkali-free glass fiber (eGF) and immerse it in a 15%–30 wt% H2O2 solution acidified with hydrochloric acid. A concentration higher than 30 wt% will increase costs, while a concentration lower than 15 wt% will prolong the subsequent removal of the sizing agent and result in incomplete removal. The mass ratio should be between 1:1 and 1.5:1, meaning approximately 1–1.5 g of alkali-free glass fiber requires 1 ml of hydrogen peroxide solution (hydrogen peroxide solution is generally measured by volume, and its specific gravity can be approximated as 1). Too much glass fiber will prevent it from dispersing properly in the solution, affecting the removal of the sizing agent; too little glass fiber will reduce efficiency and cause unnecessary waste. The solution pH should be controlled between 4 and 5, and the Cl- content in the hydrochloric acid should be controlled within a certain range. - The sizing agent has a certain corrosive effect on glass fiber. Excessive acidity (pH < 4) introduces unnecessary Cl- contamination, while excessively low acidity (pH > 5) affects the removal of the sizing agent. The fiber reacts at 40–60℃ for 5–10 minutes. Temperatures below 40℃ affect the removal of the sizing agent, while temperatures above 60℃ accelerate the self-decomposition of hydrogen peroxide, introducing side reactions and reducing the removal efficiency. Removal is incomplete in less than 5 minutes, while 5–10 minutes ensures basic removal of the sizing agent, and more than 10 minutes increases costs. Removing the original sizing agent exposes the suspended hydroxyl groups on the glass fiber surface. The fiber is then washed with deionized water until the final washing solution is neutral, yielding activated alkali-free glass fiber, named HO-eGF. The sizing agent is a component inherent in commercially available glass fiber products, generally consisting of high-molecular materials such as polyurethane and polyacrylamide, accounting for approximately 1 wt% of the total mass of the glass fiber product. Its purpose is to enhance the interfacial bonding strength of the glass fiber in the composite material. However, in this application, the presence of sizing agent will affect the exposure of hydroxyl groups on the glass fiber surface, thereby affecting the subsequent hydrolysis and condensation process. Therefore, it is necessary to use oxidizing conditions (i.e., acidified hydrogen peroxide) to remove it.

[0042] S2 APTES Modification: 3-Aminopropyltriethoxysilane (APTES) is diluted with anhydrous ethanol to prepare an APTES / anhydrous ethanol solution with a concentration of 0.5–8 wt%. The APTES concentration determines the subsequent amination level, thus affecting the catalyst loading. A concentration less than 0.5 wt% results in too few -NH2 groups, which is detrimental to subsequent catalyst capture; a concentration too high causes subsequent hydrolysis and condensation reactions to proceed too quickly, leading to an uneven condensation layer. The pH is adjusted to between 4 and 5 using hydrochloric acid. For example, in typical experiments, adding a few drops of concentrated hydrochloric acid (37 wt%) is sufficient. A pH less than 4 is unfavorable for subsequent condensation reactions, while a pH greater than 5 is unfavorable for APTES hydrolysis. Stirring at room temperature for 0.5–2 hours ensures complete hydrolysis, while stirring for more than 2 hours increases costs. The hydrolysis of APTES occurs as follows:

[0043] Si(OC2H5)3C(CH2)3NH2+3H2O→Si(OH)3C(CH2)3NH2+3C2H5OH

[0044] The obtained HO-eGF is then immersed in the solution and reacted at 40–80°C for 0.5–2 hours. The condensation reaction is exothermic and reversible. If the temperature is too low, the condensation rate will be too slow; if the temperature is too high, the reaction equilibrium will be biased towards product formation, reducing the yield. If the reaction time is less than 0.5 hours, the reaction will not have enough time to reach the equilibrium point, resulting in incomplete reaction. 2 hours is sufficient for the condensation reaction to reach equilibrium. If the reaction time is greater than 2 hours, it will increase the cost. The hydrolysis products of APTES condense with the hydroxyl groups on the glass fiber surface, as shown in the following reaction formula:

[0045] Si(OH)3C(CH2)3NH2+Si-OH (glass fiber hydroxyl groups)

[0046] →Si-O-Si(CH2)3NH2+H2O

[0047] After the reaction is complete, the glass fiber is removed and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0048] The main reason for using APTES modification is to provide a substrate for subsequent catalyst particle deposition. Since the surface of alkali-free glass fiber is smooth and chemically inert, it is difficult for the catalyst metal to adhere directly to the glass fiber surface. By modifying with APTES, a "rough" condensation layer can be formed on the glass fiber surface, increasing the contact area between the catalyst and the fiber. Furthermore, through amino functional groups, the catalyst particles can be further induced to adsorb onto the fiber surface.

[0049] S3 hydrothermal deposition solidification: Using ethylene glycol as a solvent, a mixed solution of 0.03–0.053 mol / L iron acetylacetone (Fe(acac)3), 0.01–0.018 mol / L cobalt acetylacetone (Co(acac)2), and 0.002–0.03 mol / L molybdenum hexacarbonyl (Mo(CO)6) was prepared, so that the molar percentage of Mo in the metal element was 5%–30%, and the Fe:Co molar ratio was 3:1. In terms of precursor concentration control, the total molar amount of metal elements was controlled between 0.042 and 0.101 mol / L, specifically subdivided into 0.03–0.053 mol / L iron acetylacetone (Fe(acac)3), 0.01–0.018 mol / L cobalt acetylacetone (Co(acac)2), and 0.002–0.03 mol / L molybdenum hexacarbonyl (Mo(CO)6). The molar percentage of molybdenum (Mo) in the total metal content ranges from 5% to 30%, with a Fe:Co molar ratio of 3:1. If the Mo content is less than 0.042 mol / L, the total metal content is too low, resulting in insufficient catalyst and ineffective catalysis for CNT growth. Conversely, if the Mo content is greater than 0.101 mol / L, the excessive metal content leads to two problems: firstly, metal particles tend to agglomerate, resulting in a wider particle size distribution and uneven CNT growth; secondly, the erosion effect on the fiber substrate increases, damaging the fiber's mechanical properties. A Mo content less than 5% is too low to provide effective erosion resistance, while a content greater than 30% is too high and detrimental to CNT growth.

[0050] 100g of H2N-eGF was added to the mixture, followed by 0.1–0.5 mol of sodium borohydride (NaBH4). The mixture was stirred until homogeneous, and then reduced at 80–120℃ for 1–2 hours to obtain alloy particles, which were then deposited on the glass fiber surface. Adding less than 0.1 mol of sodium borohydride resulted in incomplete reduction of the alloy particles, while adding more than 0.5 mol resulted in an overly vigorous reduction reaction, leading to uneven particle size and affecting the uniformity of subsequent CNT growth. Temperatures below 80℃ resulted in incomplete reduction of the alloy particles, while temperatures above 120℃ resulted in an overly vigorous reduction reaction, leading to uneven particle size and affecting the uniformity of subsequent CNT growth. A time of less than 1 hour resulted in incomplete reduction of the alloy particles, while a time of more than 2 hours resulted in an increased metal particle size, affecting the subsequent CNT catalytic effect. Glass fiber was filtered, washed with anhydrous ethanol, and then cured in an oven at 100–150°C for 5–10 minutes. Too low a temperature (below 100°C) or too short a time (below 5 minutes) will result in incomplete curing of the condensation layer, leading to insufficient adhesion of the alloy particles to the surface. Too high a temperature (above 150°C) or too long a time (above 10 minutes) will easily cause alloy agglomeration, affecting the CNT catalytic effect. The resulting alkali-free glass fiber carrying the low-temperature catalyst was named FeCoMo.x @eGF, where x represents the molar percentage of Mo (x = 0.05 to 0.3); when the Mo content is less than 0.05, it is too low to provide effective resistance to erosion, while when the Mo content is greater than 0.3, it is too high and not conducive to CNT growth.

[0051] Experiments have verified that the FeCoMo alloy x It has the effect of catalyzing carbon nanotubes at low temperature, with its optimal efficiency range being 450℃~550℃, and the carbon nanotube content can be controlled between 10~30wt%.

[0052] Alloy FeCoMo x Compared to Fe, Co, and their binary alloys, it exhibits lower erosion of glass fiber substrates. This is achieved through Mo incorporation, which increases the Gibbs free energy (ΔG) of the reaction between the alloy and SiO2. r G m The specific mechanism is as follows:

[0053] At 550℃:

[0054] Fe + SiO₂ → FeSiO₃ △ r G m = -75.2 kJ / mol

[0055] Co + SiO2 → CoSiO3 △ r G m = -68.9 kJ / mol

[0056] Mo + SiO2 → MoO3 + Si △ r G m = +18.7 kJ / mol

[0057] It can be seen that the reaction between Mo and SiO2 is non-spontaneous. According to the mixing rules, taking Fe:Co:Mo = 6:2:2 as an example, the alloy FeCoMo... 0.2 ΔG of reaction with SiO2 合金 It can be estimated as follows:

[0058] △G 合金 =0.6×△G Fe +0.2×△G Co +0.2×△G Mo +△G mix

[0059] Among them, △G mix For the mixed energy of metals, the value of ΔG can be calculated from the table. mix = +5.2 kJ / mol, substituting into the above equation, we get:

[0060] △G 合金=0.6×-75.2+0.2×-68.9+0.2×18.7+5.2=-49.96KJ / mol

[0061] By increasing △G 合金 The thermodynamic tendency of the alloy to corrode glass fiber is reduced by 8 to 10 orders of magnitude. Combined with the passivation kinetics of Mo on FeCo alloy, this achieves FeCoMo x The series of alloys enhance the corrosion resistance of glass fiber at high temperatures.

[0062] To address the limitations of existing methods for growing carbon nanotubes on the surface of alkali-free glass fibers in terms of equipment and performance, this invention utilizes 3-aminopropyltriethoxysilane (APTES) to construct an amino-functionalized interface. Catalyst alloy particles are synthesized and immobilized via a hydrothermal method. This catalyst alloy offers advantages such as catalytic carbon nanotube growth at temperatures below the softening point of alkali-free glass fibers, minimal fiber erosion by the catalyst components, and the elimination of the need for subsequent PECVD methods for carbon nanotube growth. Therefore, it is suitable for the large-scale synthesis and preparation of carbon nanotube-modified alkali-free glass fibers.

[0063] Some embodiments of the present invention also provide a low-temperature carbon nanotube catalyst, wherein the low-temperature carbon nanotube catalyst is supported on the surface of alkali-free glass fiber, and the low-temperature carbon nanotube catalyst is prepared by the method described above.

[0064] Some embodiments of the present invention also provide an application of the above-mentioned low-temperature carbon nanotube catalyst in chemical vapor deposition.

[0065] In the above technical solution, the present invention first treats alkali-free glass fiber (eGF) with a certain concentration of hydrogen peroxide (H2O2) to remove its original sizing agent. Then, 3-aminopropyltriethoxysilane (APTES) is used as a surface modifier to construct amino ligands on the glass fiber surface. Subsequently, FeCoMox ternary catalyst particles are uniformly deposited using a hydrothermal method with the assistance of the amino ligands, where x represents the molar percentage of Mo. The catalyst is then cured by heating to obtain alkali-free glass fiber (FeCoMox@eGF) with a tightly loaded catalyst. The present invention also provides a method for growing carbon nanotubes based on FeCoMox@eGF material. Through conventional chemical vapor deposition, quantitative growth of carbon nanotubes is achieved at temperatures below the softening point of glass fiber.

[0066] This approach eliminates the need for an isolation layer, directly utilizing interfacial molecular design to achieve a stable metal-glass fiber bond while simultaneously meeting the corrosion resistance requirements for low-temperature catalytic carbon nanotube (CNT) growth. The change in tensile strength after CNT growth demonstrates that lower corrosion levels correlate with higher retention of tensile strength.

[0067] The specific embodiments of the present invention will be described in further detail below with reference to examples, but this should not be construed as a limitation on the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention still fall within the scope of protection of the present invention.

[0068] Unless otherwise specified, all materials and reagents mentioned below are commercially available products well known to those skilled in the art; unless otherwise specified, all methods described are methods known in the art. Unless otherwise defined, the technical or scientific terms used should have the ordinary meaning understood by those skilled in the art to which this invention pertains.

[0069] Example 1

[0070] This embodiment provides a method for preparing FeCoMo alloy by loading 5 at% Mo onto the surface of alkali-free glass fiber. 0.05 @eGF's method.

[0071] Take 100g of alkali-free glass fiber (eGF), immerse it in 15wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH 4, heat the solution to 40℃ and react for 5min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0072] APTES was diluted with anhydrous ethanol to prepare a 0.5 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 4 using 37 wt% hydrochloric acid. The solution was stirred at room temperature for 0.5 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution. The temperature was raised to 40 °C and the reaction was carried out for 0.5 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0073] Take 1000 mL of ethylene glycol, and add 10.59 g of Fe(acac)3, 2.57 g of Co(acac)2, and 0.53 g of Mo(CO)6 sequentially. Stir until completely dissolved to prepare a mixed solution with Fe(acac)3 concentration of 0.03 mol / L, Co(acac)2 concentration of 0.01 mol / L, and Mo(CO)6 concentration of 0.002 mol / L. Add 100 g of H2N-eGF to the mixed solution, then add 0.1 mol of NaBH4. Stir the mixture thoroughly, heat to 80 °C, and reduce for 1 h to reduce the FeCoMo alloy particles. Filter the reacted H2N-eGF using vacuum filtration, wash with anhydrous ethanol until the final wash solution is colorless, and then cure in an oven at 100 °C for 5 min to obtain alkali-free glass fiber loaded with a low-temperature catalyst, named FeCoMo. 0.05 @eGF.

[0074] Example 2

[0075] This embodiment provides a FeCoMo alloy prepared by loading 30 at% Mo onto the surface of alkali-free glass fiber. 0.3 @eGF's method.

[0076] Take 100g of alkali-free glass fiber (eGF), immerse it in 30wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=5, heat the solution to 60℃ and react for 10min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0077] APTES was diluted with anhydrous ethanol to prepare an 8 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 5 using 37 wt% hydrochloric acid. The solution was stirred at room temperature for 2 hours. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution. The temperature was raised to 80°C and the reaction was carried out for 2 hours. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0078] Take 1000 mL of ethylene glycol, and add 18.72 g of Fe(acac)3, 4.63 g of Co(acac)2, and 7.92 g of Mo(CO)6 sequentially. Stir until completely dissolved to prepare a solution with Fe(acac)3 concentration of 0.053 mol / L, Co(acac)2 concentration of 0.018 mol / L, and Mo(CO)6 concentration of 0.03 mol / L. Add 100 g of H2N-eGF to the mixture, then add 0.5 mol of NaBH4. Stir the mixture thoroughly, heat to 120 °C, and reduce for 2 h to reduce the FeCoMo alloy particles. Filter the reacted H2N-eGF using vacuum filtration, wash with anhydrous ethanol until the final wash solution is colorless, and then cure in an oven at 150 °C for 10 min to obtain alkali-free glass fiber loaded with a low-temperature catalyst, named FeCoMo. 0.3 @eGF.

[0079] Example 3

[0080] This embodiment provides a FeCoMo alloy prepared by loading 15 at% Mo onto the surface of alkali-free glass fiber. 0.15 @eGF's method.

[0081] Take 100g of alkali-free glass fiber (eGF), immerse it in 20wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=4.5, heat the solution to 50℃ and react for 8min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0082] APTES was diluted with anhydrous ethanol to prepare a 4 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 4.5 with 37 wt% hydrochloric acid and stirred at room temperature for 0.8 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution, heated to 60 °C, and reacted for 1 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0083] Take 1000 mL of ethylene glycol, and add 14.13 g of Fe(acac)3, 3.34 g of Co(acac)2, and 2.64 g of Mo(CO)6 sequentially. Stir until completely dissolved to prepare a solution with Fe(acac)3 concentration of 0.04 mol / L, Co(acac)2 concentration of 0.013 mol / L, and Mo(CO)6 concentration of 0.01 mol / L. Add 100 g of H2N-eGF to the mixture, then add 0.3 mol of NaBH4. Stir the mixture thoroughly, heat to 100 °C, and reduce for 1.5 h to reduce the FeCoMo alloy particles. Filter the reacted H2N-eGF using vacuum filtration, wash with anhydrous ethanol until the final wash solution is colorless, and then cure in an oven at 125 °C for 8 min to obtain alkali-free glass fiber loaded with a low-temperature catalyst, named FeCoMo. 0.15 @eGF.

[0084] Example 4

[0085] This embodiment provides a FeCoMo alloy prepared by loading 20 at% Mo onto the surface of alkali-free glass fiber. 0.2 @eGF's method.

[0086] Take 100g of alkali-free glass fiber (eGF), immerse it in 24wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=5, heat the solution to 50℃ and react for 8min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0087] APTES was diluted with anhydrous ethanol to prepare a 6.5 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 5 using 37 wt% hydrochloric acid. The solution was stirred at room temperature for 0.8 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution. The temperature was raised to 70 °C and the reaction was carried out for 1.2 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0088] Take 1000 mL of ethylene glycol, and add 15.89 g of Fe(acac)3, 3.86 g of Co(acac)2, and 3.96 g of Mo(CO)6 sequentially. Stir until completely dissolved to prepare a solution with Fe(acac)3 concentration of 0.045 mol / L, Co(acac)2 concentration of 0.015 mol / L, and Mo(CO)6 concentration of 0.015 mol / L. Add 100 g of H2N-eGF to the mixture, then add 0.35 mol of NaBH4. Stir the mixture thoroughly, heat to 110 °C, and reduce for 1.2 h to reduce the FeCoMo alloy particles. Filter the reacted H2N-eGF using vacuum filtration, wash with anhydrous ethanol until the final wash solution is colorless, and then cure in an oven at 125 °C for 10 min to obtain alkali-free glass fiber loaded with a low-temperature catalyst, named FeCoMo. 0.2 @eGF.

[0089] Example 5

[0090] This embodiment provides a FeCoMo alloy prepared by loading 25 at% Mo onto the surface of alkali-free glass fiber. 0.25 @eGF's method.

[0091] Take 100g of alkali-free glass fiber (eGF), immerse it in 25wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=5, heat the solution to 55℃ and react for 8min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0092] APTES was diluted with anhydrous ethanol to prepare a 7.5 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 5 with 37 wt% hydrochloric acid and stirred at room temperature for 1.5 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution, heated to 40 °C, and reacted for 1.5 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0093] Take 1000 mL of ethylene glycol, and add 18.31 g of Fe(acac)3, 4.37 g of Co(acac)2, and 6.07 g of Mo(CO)6 sequentially. Stir until completely dissolved to prepare a solution with Fe(acac)3 concentration of 0.051 mol / L, Co(acac)2 concentration of 0.017 mol / L, and Mo(CO)6 concentration of 0.023 mol / L. Add 100 g of H2N-eGF to the mixture, then add 0.4 mol of NaBH4. Stir the mixture thoroughly, heat to 115 °C, and reduce for 1.5 h to reduce the FeCoMo alloy particles. Filter the reacted H2N-eGF using vacuum filtration, wash with anhydrous ethanol until the final wash solution is colorless, and then cure in an oven at 140 °C for 10 min to obtain alkali-free glass fiber loaded with a low-temperature catalyst, named FeCoMo. 0.25 @eGF.

[0094] Example 6

[0095] This embodiment provides a FeCoMo alloy prepared by loading 18 at% Mo onto the surface of alkali-free glass fiber. 0.18 @eGF's method.

[0096] Take 100g of alkali-free glass fiber (eGF), immerse it in 18wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=4, heat the solution to 50℃ and react for 6min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0097] APTES was diluted with anhydrous ethanol to prepare a 3.5 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 4 using 37 wt% hydrochloric acid. The solution was stirred at room temperature for 0.8 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution. The temperature was raised to 40 °C and the reaction was carried out for 0.8 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0098] Take 1000 mL of ethylene glycol, and add 14.83 g of Fe(acac)3, 3.60 g of Co(acac)2, and 2.90 g of Mo(CO)6 sequentially. Stir until completely dissolved to prepare a solution with Fe(acac)3 concentration of 0.042 mol / L, Co(acac)2 concentration of 0.014 mol / L, and Mo(CO)6 concentration of 0.011 mol / L. Add 100 g of H2N-eGF to the mixture, then add 0.22 mol of NaBH4. Stir the mixture thoroughly, heat to 95 °C, and reduce for 1.2 h to reduce the FeCoMo alloy particles. Filter the reacted H2N-eGF using vacuum filtration, wash with anhydrous ethanol until the final wash solution is colorless, and then cure in an oven at 110 °C for 6 min to obtain alkali-free glass fiber loaded with a low-temperature catalyst, named FeCoMo. 0.18 @eGF.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing FeCo@eGF by loading a Mo-free FeCo alloy onto an alkali-free glass fiber surface.

[0101] Except for not adding Mo(CO)6, the other methods are the same as in Example 6.

[0102] Application Example 1

[0103] Carbon nanotubes were grown from the fiber materials obtained in Examples 1-6 and Comparative Example 1 using chemical vapor deposition. The gas source was an acetylene / argon mixture with a volume ratio of 2.45% acetylene. The deposition temperature was 525°C, and the deposition time was 5 min. The resulting material was named CNT / FeCoMo. x @eGF, where x represents the molar percentage of Mo (x = 0.05–0.3). CNT / FeCoMo x Information such as the carbon nanotube content and fiber strength of @eGF is summarized in Table 1.

[0104] Table 1. CNT / FeCoMo in Examples 1-6 and Comparative Example 1 x @eGF performance parameters

[0105]

[0106]

[0107] As can be seen from the data in Table 1, the strength loss of the fiber after CNT growth is smaller with the increase of the Mo content in the catalyst. When the Mo content is 20% (Example 4), the strength loss is already less than 5%. Although further increasing the Mo content can still reduce the loss, it has a significant marginal effect. However, although Mo can reduce the erosion effect of the catalyst on the fiber, it will also reduce the growth efficiency of CNT. Therefore, it is necessary to reasonably control the Mo content, which should not be too high or too low.

[0108] The results of this application example readily suggest that by appropriately changing the CNT growth conditions (acetylene content, temperature, time, etc.), alkali-free glass fibers with higher or lower carbon nanotube content can be prepared, and the trends in their strength and CNT content are basically consistent.

[0109] Example 7

[0110] This embodiment provides a method for preparing FeCoMo alloy by modifying glass fibers with 6 wt% 3-aminopropyltriethoxysilane and then loading 15 at% Mo onto the surface of alkali-free glass fibers. 0.15 The method of @eGF-6%.

[0111] Take 100g of alkali-free glass fiber (eGF), immerse it in 20wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=4.5, heat the solution to 50℃ and react for 8min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0112] APTES was diluted with anhydrous ethanol to prepare a 6 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 4.5 with 37 wt% hydrochloric acid and stirred at room temperature for 0.8 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution, heated to 60 °C, and reacted for 1 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0113] The subsequent steps are the same as in Example 3.

[0114] Example 8

[0115] This embodiment provides a method for preparing FeCoMo alloy by modifying glass fibers with 8 wt% 3-aminopropyltriethoxysilane and then loading 15 at% Mo onto the surface of alkali-free glass fibers. 0.15 @eGF-8% method.

[0116] Take 100g of alkali-free glass fiber (eGF), immerse it in 20wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=4.5, heat the solution to 50℃ and react for 8min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0117] APTES was diluted with anhydrous ethanol to prepare an 8 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 4.5 with 37 wt% hydrochloric acid and stirred at room temperature for 0.8 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution, heated to 60 °C, and reacted for 1 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0118] The subsequent steps are the same as in Example 3.

[0119] Example 9

[0120] This embodiment provides a method for preparing FeCoMo alloy by modifying glass fibers with 2 wt% 3-aminopropyltriethoxysilane and then loading 15 at% Mo onto the surface of alkali-free glass fibers. 0.15 The method of @eGF-2%.

[0121] Take 100g of alkali-free glass fiber (eGF), immerse it in 20wt% H2O2 solution, add 37wt% hydrochloric acid to acidify the solution to pH=4.5, heat the solution to 50℃ and react for 8min to oxidize and remove the sizing agent, filter the fiber, wash the fiber with deionized water 3 times until the last washing solution is neutral, and obtain the activated alkali-free glass fiber, named HO-eGF;

[0122] APTES was diluted with anhydrous ethanol to prepare a 2 wt% APTES / anhydrous ethanol solution. The pH of the solution was adjusted to 4.5 with 37 wt% hydrochloric acid and stirred at room temperature for 0.8 h. The HO-eGF obtained above was then immersed in the stirred APTES / anhydrous ethanol solution, heated to 60 °C, and reacted for 1 h. After the reaction was completed, the alkali-free glass fiber was filtered by vacuum filtration and washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber, named H2N-eGF.

[0123] The subsequent steps are the same as in Example 3.

[0124] Comparative Example 2

[0125] This comparative example provides a method for preparing FeCoMo alloy by modifying glass fibers with an excessively high concentration (15 wt%) of 3-aminopropyltriethoxysilane, followed by loading 15 at% Mo onto the surface of alkali-free glass fibers. 0.15 The method for @eGF-15% is the same as in Example 7, except for the concentration conditions.

[0126] Application Example 2

[0127] The fiber materials obtained in Examples 7-9 and Comparative Example 2 were used to grow carbon nanotubes using chemical vapor deposition. The gas source was a 2.45% acetylene / argon mixture, the deposition temperature was 525°C, and the deposition time was 5 min. The resulting material was named CNT / FeCoMo. 0.15 @eGF-n%, where n represents the concentration of 3-aminopropyltriethoxysilane. CNT / FeCoMo 0.15 Information such as the @eGF-n% carbon nanotube content and fiber strength is summarized in Table 2.

[0128] Table 2. CNT / FeCoMo in Examples 3, 7-9 and Comparative Example 2 0.15 Performance parameters of @eGF-n%

[0129]

[0130] As shown in Table 2, the strength loss of fibers after CNT growth gradually decreases with increasing 3-aminopropyltriethoxysilane modification concentration. However, although high concentrations of 3-aminopropyltriethoxysilane can delay fiber damage, they also result in an excessively thick modification layer on the fiber surface, leading to catalyst burial and incomplete exposure, thus reducing CNT growth efficiency. Comparative Example 2 shows that when the 3-aminopropyltriethoxysilane modification concentration increases to 15 wt%, the CNT content decreases by 64.9% compared to a 4 wt% concentration, while the fiber strength only increases by 13.6%. Therefore, it is necessary to rationally control the 3-aminopropyltriethoxysilane modification concentration to achieve the optimal balance.

[0131] The results of this application example readily suggest that by appropriately altering the growth conditions of CNTs (acetylene content, temperature, time, etc.), alkali-free glass fibers with higher or lower carbon nanotube content can be prepared, and the trends in their strength and CNT content are basically consistent.

[0132] Example 10

[0133] This embodiment, based on embodiment 4, uses different restoration conditions. The specific steps are as follows:

[0134] Take 100g of alkali-free glass fiber (eGF) and obtain H2N-eGF using the same method as in Example 4;

[0135] Take 1000 mL of ethylene glycol, and add 15.89 g of Fe(acac)3, 3.86 g of Co(acac)2, and 3.96 g of Mo(CO)6 sequentially. Stir until completely dissolved to prepare a solution with Fe(acac)3 concentration of 0.045 mol / L, Co(acac)2 concentration of 0.015 mol / L, and Mo(CO)6 concentration of 0.015 mol / L. Add 100 g of H2N-eGF to the mixture, then add 0.15 mol of NaBH4. Stir the mixture thoroughly, heat to 110 °C, and reduce for 1.2 h to reduce the FeCoMo alloy particles. Filter the reacted H2N-eGF using vacuum filtration, wash with anhydrous ethanol until the final wash solution is colorless, and then cure in an oven at 125 °C for 10 min to obtain alkali-free glass fiber loaded with a low-temperature catalyst, named FeCoMo. 0.2 @eGF-0.15M.

[0136] Example 11

[0137] Similar to Example 10, only the amount of NaBH4 added was changed to 0.25 mol, while the other steps remained the same. The resulting material was named FeCoMo. 0.2 @eGF-0.25M.

[0138] Example 12

[0139] Similar to Example 10, only the amount of NaBH4 added was changed to 0.5 mol, while the other steps remained the same. The resulting material was named FeCoMo. 0.2 @eGF-0.5M.

[0140] Comparative Example 3

[0141] This comparative example is similar to Examples 10-12, but NaBH4 is not used as a reducing agent; instead, ethylene glycol solvent is used to provide the reduction conditions. All other steps remain unchanged, and the resulting material is named FeCoMo. 0.2 @eGF-EG.

[0142] Application Example 3

[0143] Take 1g of each of the materials obtained in Examples 10-12 and Comparative Example 3, and use an excess of 68wt% nitric acid to completely dissolve the surface metal components, and measure the loaded metal components.

[0144] The fiber materials obtained in Examples 10-12 and Comparative Example 3 were then used to grow carbon nanotubes using chemical vapor deposition. The gas source was a 2.45% acetylene / argon mixture, the deposition temperature was 525°C, and the deposition time was 5 min. The resulting material was named CNT / FeCoMo. 0.2 @eGF-nM, where n represents the amount of NaBH4 used. CNT / FeCoMo 0.2 The contents of various metal components and carbon nanotubes of @eGF-nM are summarized in Table 3.

[0145] Table 3. CNT / FeCoMo in Examples 4, 10-12 and Comparative Example 3 0.2 Performance parameters of @eGF-nM

[0146]

[0147]

[0148] As can be seen from the data in Table 3 above, the total content of metal components gradually increases with the gradual addition of NaBH4 until 0.35 mol is added, at which point the total content of metals approaches the theoretical loading, and all metals are completely reduced.

[0149] However, the changes in metal composition are inconsistent during the addition of the reducing agent NaBH4. Mo(CO)6 decomposes into elemental Mo at a certain temperature, thus requiring the weakest reduction conditions, resulting in a higher content when NaBH4 is insufficient. Fe and Co have similar elemental properties, and their reduction generally follows the feed ratio with the addition of NaBH4. The consequence of these results is that when the reducing agent NaBH4 is insufficient (<0.35 mol), the total metal content is low, and the Mo content is high, leading to a lower content of CNTs grown in the final product. When the reducing agent is sufficient or in excess, the metal composition basically matches the theoretical content, and the content of the grown CNTs is also relatively close to the theoretical content.

[0150] Although the addition of excess NaBH4 does not affect the final CNT content, it significantly affects their morphology. This is mainly because the excessive reducing agent leads to overly rapid metal reduction, resulting in uneven particle size distribution. Figure 1 (Example 1) and Figure 2 The comparison in (Example 3) shows that although the Mo content increased, the content and morphology of carbon nanotubes on the fiber surface did not change significantly. Figure 3 (Example 4) and Figure 4 A comparison with (Example 12) shows that, Figure 4 The carbon nanotubes in the material exhibited significant entanglement and size inhomogeneity, indicating that excessive reducing agent is actually detrimental to the consistency of the material, but this does not affect the carbon nanotube content or catalyst composition of the material.

[0151] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0152] The numerical range described in this invention includes all values ​​within this range, and also includes any range value composed of any two values ​​within this range. Different values ​​of the same indicator appearing in all embodiments of this invention can be arbitrarily combined to form a range value.

[0153] The technical features in the claims and / or specification of this invention can be combined, and the combination is not limited to the combinations obtained through reference in the claims. Technical solutions obtained by combining the technical features in the claims and / or specification are also within the scope of protection of this invention.

[0154] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a low-temperature carbon nanotube catalyst, characterized by, Includes the following steps: S1 Fiber pretreatment: immerse the E-glass fiber in the hydrochloric acid acidified solution, and control the pH value between 4 and 5, after reaction and cleaning, the activated E-glass fiber is obtained. S1 Fiber pretreatment: immerse the E-glass fiber in the hydrochloric acid acidified solution, and control the pH value between 4 and 5, after reaction and cleaning, the activated E-glass fiber is obtained. S23-aminopropyltriethoxysilane modification: The pH of the 3-aminopropyltriethoxysilane / anhydrous ethanol solution was adjusted to between 4 and 5, and the mixture was stirred at room temperature, resulting in the following hydrolysis reaction: ； The activated alkali-free glass fiber obtained in step S1 is then immersed in the solution, allowing the hydrolysis product of 3-aminopropyltriethoxysilane to undergo the following condensation reaction with the hydroxyl groups on the surface of the alkali-free glass fiber: ； After the reaction is complete, the alkali-free glass fiber is washed with anhydrous ethanol until neutral to obtain amino-modified alkali-free glass fiber; the concentration of the 3-aminopropyltriethoxysilane / anhydrous ethanol solution is 0.5wt%~8wt%. S3 Hydrothermal Deposition and Curing: The amino-modified alkali-free glass fiber obtained in step S2 is added to a ethylene glycol mixed solution of iron acetylacetone, cobalt acetylacetone and molybdenum hexacarbonyl, and then 0.1~0.5 mol of sodium borohydride is added. The mixture is stirred evenly and reduced to obtain alloy particles deposited on the surface of the alkali-free glass fiber. The alkali-free glass fiber is filtered, washed with anhydrous ethanol, and then dried and cured to obtain alkali-free glass fiber carrying a low-temperature catalyst, which is the low-temperature carbon nanotube catalyst; the molar ratio of molybdenum in the ethylene glycol mixed solution of iron acetylacetone, cobalt acetylacetone and molybdenum hexacarbonyl is 5% to 30%.

2. The method for preparing a low-temperature carbon nanotube catalyst according to claim 1, wherein In step S1, the concentration of the H2O2 solution is 15wt%~30wt%.

3. The method for preparing the low-temperature carbon nanotube catalyst as described in claim 1, characterized in that, In step S1, the reaction temperature is 40~60℃ and the time is 5~10min.

4. The method for preparing the low-temperature carbon nanotube catalyst as described in claim 1, characterized in that, In step S2, the stirring time at room temperature is 0.5~2h.

5. The method for preparing the low-temperature carbon nanotube catalyst as described in claim 1, characterized in that, In step S2, the temperature of the condensation reaction is 40~80℃ and the time is 0.5~2h.

6. The method for preparing the low-temperature carbon nanotube catalyst according to claim 1, characterized in that, In step S3, the concentration of iron acetylacetone in the ethylene glycol mixed solution of iron acetylacetone, cobalt acetylacetone, and molybdenum hexacarbonyl is 0.03~0.053 mol / L, the concentration of cobalt acetylacetone is 0.01~0.018 mol / L, and the concentration of molybdenum hexacarbonyl is 0.002~0.03 mol / L.

7. The method for preparing the low-temperature carbon nanotube catalyst according to claim 1, characterized in that, In step S3, the molar ratio of iron to cobalt in the ethylene glycol mixed solution of iron acetylacetone, cobalt acetylacetone, and molybdenum hexacarbonyl is 3:

1.

8. The method for preparing the low-temperature carbon nanotube catalyst according to claim 1, characterized in that, In step S3, the reduction temperature is 80~120℃ and the reduction time is 1~2h.

9. The method for preparing the low-temperature carbon nanotube catalyst according to claim 1, characterized in that, In step S3, the drying and curing temperature is 100~150℃, and the drying time is 5~10min.

10. The method for preparing the low-temperature carbon nanotube catalyst according to claim 1, characterized in that, In step S3, the molar percentage of molybdenum in the alkali-free glass fiber of the low-temperature catalyst is 0.05~0.

3.

11. The method for preparing the low-temperature carbon nanotube catalyst according to claim 1, characterized in that, In step S3, the carbon nanotube content in the alkali-free glass fiber of the low-temperature catalyst is 10~30wt%.

12. A low-temperature carbon nanotube catalyst, characterized in that, The low-temperature carbon nanotube catalyst is supported on the surface of alkali-free glass fiber; the low-temperature carbon nanotube catalyst is prepared by the method according to any one of claims 1-11.

13. The application of the low-temperature carbon nanotube catalyst of claim 12 in chemical vapor deposition.

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