CN-122010097-A - Single-wall carbon nano tube and continuous preparation method thereof

CN122010097ACN 122010097 ACN122010097 ACN 122010097ACN-122010097-A

Abstract

The invention belongs to the technical field of carbon nanotubes, and relates to a single-walled carbon nanotube and a single-walled carbon nanotube continuous preparation method based on methane and a floating catalyst, which comprises the steps of continuously injecting a metal catalyst precursor and optional auxiliary agents into an evaporation chamber in a spraying manner, and introducing a first path of carrier gas into the obtained mixed gas flow to accelerate the gas flow, wherein the first path of carrier gas is inert gas, so as to obtain a raw material flow; continuously injecting the raw material flow, a second path of carrier gas and a silicon source precursor into a high-temperature tubular reactor for high-temperature vapor deposition reaction, wherein the second path of carrier gas contains methane, hydrogen and inert gas, and in the high-temperature vapor deposition reaction process, the metal catalyst precursor is decomposed to form active catalyst nano particles, and the methane is catalytically cracked and deposited, so that single-wall carbon nanotubes are continuously grown. The method can improve the yield and purity of the single-walled carbon nanotubes, and the diameter distribution of the single-walled carbon nanotubes is uniform.

Inventors

LIU CHAONONG
HONG JIANGBIN
FANG CHONGQING
ZHAO LIPING

Assignees

厦门凯纳石墨烯技术股份有限公司
永安市凯纳新材料科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260408

Claims (9)

1. A continuous preparation method of single-walled carbon nanotubes based on methane and a floating catalyst, which is characterized by comprising the following steps: s1, continuously injecting a metal catalyst precursor and optional auxiliary agents into an evaporation chamber in a spraying mode, so that raw materials are evaporated to form mixed gas flow containing the metal catalyst precursor and the optional auxiliary agents, and introducing a first path of carrier gas into the obtained mixed gas flow to accelerate the gas flow, wherein the first path of carrier gas is inert gas, and a raw material flow is obtained; S2, continuously injecting a raw material flow, a second path of carrier gas and a silicon source precursor into a high-temperature tubular reactor for high-temperature vapor deposition reaction, wherein the silicon source precursor is at least one selected from hexamethyldisiloxane, polymethylsiloxane, trimethylsilane, tetramethylsilane, tetramethoxysilane, tetraethoxysilane, ethyl orthosilicate and octamethyl cyclotetrasiloxane, the second path of carrier gas contains methane, hydrogen and inert gas, and in the high-temperature vapor deposition reaction process, the metal catalyst precursor is decomposed to form active catalyst nano particles, and methane is catalytically cracked and deposited, so that single-wall carbon nanotubes are continuously grown.
2. The continuous process for preparing single-walled carbon nanotubes based on methane and a floating catalyst according to claim 1 further comprising premixing the metal catalyst precursor and optional promoter prior to spraying into the vaporization chamber.
3. The continuous production method of single-walled carbon nanotubes based on methane and a floating catalyst according to claim 1, wherein the silicon source precursor is injected into the high-temperature tubular reactor in such a manner that the silicon source precursor is injected into the tubule located in the high-temperature tubular reactor at a flow rate of microliters/minute, and the position of the tubule is set such that the difference between the temperature at the discharge port of the tubule and the temperature of the high-temperature vapor deposition reaction does not exceed 200 ℃.
4. The continuous preparation method of the single-walled carbon nanotube based on methane and a floating catalyst according to claim 1 is characterized in that the mass ratio of the metal catalyst precursor to the auxiliary agent is 1 (0.04-0.2), and the ratio of the total consumption of the metal catalyst precursor and the auxiliary agent to the consumption of the silicon source precursor is 40mg (1-10) mu L.
5. The continuous preparation method of single-walled carbon nanotubes based on methane and a floating catalyst according to claim 1, wherein the metal catalyst precursor is at least one selected from ferrocene, cobaltocene, nickel-dicyclopentadienyl, ferric acetylacetonate and ferric nonacarbonyl, and the auxiliary agent is a sulfur-containing compound.
6. The continuous preparation method of single-walled carbon nanotubes based on methane and a floating catalyst according to claim 1, wherein the flow rate of the first carrier gas is 500-2000 sccm, and the total flow rate of the second carrier gas is 2200-11000 sccm.
7. The continuous preparation method of single-walled carbon nanotubes based on methane and a floating catalyst according to claim 1, wherein the volume ratio of methane in the second carrier gas is 5-12%, the volume ratio of hydrogen is 48-60%, and the volume ratio of inert gas is 30-50%.
8. The continuous preparation method of single-walled carbon nanotubes based on methane and a floating catalyst according to any one of claims 1 to 7, wherein the temperature of the mixed gas stream formed by evaporation of the raw materials is 150 to 300 ℃, the conditions of the high-temperature vapor deposition reaction include a reaction temperature of 1000 to 1200 ℃, a reaction pressure of normal pressure, and a residence time of the materials in the reactor of 3 to 10s.
9. A single-walled carbon nanotube prepared by the method of any of claims 1-8.

Description

Single-wall carbon nano tube and continuous preparation method thereof Technical Field The invention belongs to the technical field of carbon nanotubes, and particularly relates to a single-walled carbon nanotube and a continuous preparation method of the single-walled carbon nanotube based on methane and a floating catalyst. Background Single-wall carbon nanotubes (SWCNTs) have wide application prospects in the fields of nano electronic devices, aerospace materials, energy storage and conversion, biomedicine and the like due to excellent optical, electrical, thermal, mechanical properties and chemical stability. The realization of low-cost, controllable and large-scale preparation of high-quality SWCNTs is the key to the trend of practical application. Currently, the common methods for preparing SWCNTs are mainly arc discharge, laser evaporation, and Chemical Vapor Deposition (CVD). Among them, the CVD method is considered as the most promising production method because of stable and controllable reaction conditions and mass production. The chemical vapor deposition method (FCCVD) of the floating catalyst is a derivative form of CVD, and is mainly characterized in that a catalyst precursor and an auxiliary agent are evaporated at a certain temperature to form gas or steam, the gas and the carbon source gas are introduced into a high-temperature reaction zone together, the carbon source is cracked into carbon atoms, catalyst nano particles are directly formed in a gas phase environment and the chemical vapor deposition method of the floating catalyst for catalyzing the growth of SWCNTs （Parametric analysis of chirality families and diameter distributions in single-wall carbon nanotube production by the floating catalyst method[J]. Ranadeep,Bhowmick,and,et al. Carbon, 2008, 46(6):907-922.）. avoids the use of a substrate, can realize continuous and macro preparation of the SWCNTs, and is particularly suitable for the situations requiring high yield, high purity and direct application. Methane, a simple structure hydrocarbon, is an ideal carbon source for growing high quality, low defect SWCNTs. However, the molecular structure of methane is extremely stable, and the cracking process requires high energy, higher reaction temperatures and more efficient catalysts. In the prior art, when the FCCVD method using methane as a carbon source is used for preparing SWCNTs, the preparation method mainly has the following challenges that (1) the overall efficiency of the catalyst is low, so that the final yield of single-wall carbon nanotubes is low, (2) the coupling property of technological parameters is strong, accurate control is difficult to realize, the operation repeatability is poor, (3) the particle size distribution of the catalyst is non-uniform, so that the diameter of the SWCNTs is overlarge, the chiral distribution is too wide, and (4) by-products such as amorphous carbon, carbon black, graphite flakes and the like are easier to generate at high temperature, and the by-product impurities are easy to cover the surface of the catalyst, so that the catalyst is poisoned, the growth of the carbon tubes is stopped, and the purity of the product is influenced. CN120057903a discloses a single-walled carbon nanotube system and a method for preparing the same with the aid of aerosol, uniform and fine catalyst particles are obtained through atomization and screening treatment, the G/D ratio of the single-walled carbon nanotube is only 16 at maximum, and the purity is 72%. The single-walled carbon nanotubes obtained by the method have poor quality and low purity, which may be caused by the fact that the catalyst particles cannot reach a uniform and fine state. CN114162804a discloses a device and a method for preparing single-walled carbon nanotubes by scalable floating catalytic cracking, which comprises the steps of preparing catalyst nanoparticles with narrower size distribution, and then sending the catalyst nanoparticles with narrower size distribution into a reaction chamber to react with a carbon source gas mixture before no further growth by a catalyst pretreatment unit. The G/D ratio of the single-walled carbon nanotube obtained by the method is 78 at most, the purity is about 80%, the quality of the single-walled carbon nanotube is low, the purity is low, and the catalyst particles in actual reaction may not reach the ideal size distribution requirement. The G/D is calculated according to Raman spectrum, the G peak (1580 cm -1) represents an ordered and complete sp2 hybridized carbon structure in the single-walled carbon nanotube, the G peak is a mark of graphitization degree and crystallization quality, the D peak (1350 cm -1) represents a disordered, defective or sp3 hybridized carbon structure in the single-walled carbon nanotube, the mark of defect density, the G peak intensity ratio (G/D) can reflect defect degree, and in general, the higher the quality of the single-walled carbon nanotube is, the larger