Catalyst for preparing multi-walled carbon nanotubes, preparation method and application thereof

Abstract

The invention discloses a catalyst for preparing multi-walled carbon nanotubes and its preparation method and application. The catalyst uses MgO as a carrier, metal Fe, Co or Ni as an active component, and metal Mo as an auxiliary agent. Its general chemical formula can be expressed as xM a -Mo b / MgO, where x is the molar percentage of M in MgO, M is one of Fe, Co or Ni, and a:b represents the molar ratio of M to Mo. The catalyst can form a porous porous structure with high catalyst load, large specific surface area and good activity, which provides sufficient space for the growth of carbon nanotubes; and can prepare high-quality carbon nanotubes. The catalyst provided by the present invention also has the advantages of simple preparation method, safe and feasible preparation process, good large-scale preparation activity, and large specific surface area (up to 154m 2 / g) and excellent spatial structure. The catalyst provided by the invention can prepare high-quality carbon nanotubes, the I_G / I_D can reach 17, the average diameter is 8.7nm, and the carbon content of the crude product of the carbon nanotubes exceeds 92%.

Description

technical field [0001] The invention belongs to the technical field of carbon nanotube preparation, and in particular relates to a catalyst for preparing multi-walled carbon nanotubes, a preparation method and application thereof. Background technique [0002] Multi-walled carbon nanotube (MWCNT) was first prepared by Japanese researcher Ijima in 1991. It can be regarded as a seamless tubular material formed by curling graphene sheets. Multi-walled carbon nanotubes have many excellent properties, such as good electrical conductivity, excellent thermal conductivity, ultra-high strength and tensile strength, large specific surface area and efficient catalytic performance, etc., which make it in energy, chemical It has broad application prospects in fields such as physical sensors, catalytic materials and composite materials. [0003] After nearly 30 years of development, the preparation of multi-walled carbon nanotubes has developed rapidly. The main preparation methods are ...

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Problems solved by technology

Chinese patent CN106458593A discloses a large-diameter, low-density carbon nanotube and a method for preparing the carbon nanotube. It uses an impregnation method to impregnate the active component on alumina, and the catalyst prepared by this method has a very small specific surface area. The growth space of multi-walled carbon nanotubes is limited, which is not conducive to the growth of carbon nanotubes; Chinese patent CN102145883A discloses a direct preparation of ultra-high-purity carbon nanotubes and its preparation method. The preparation process parameters of this method are complex to control and require Catalyst grains are dispersed on the surface of the inert carrier, and the space of the catalyst cannot be fully utilized; Chinese patent CN109665512A discloses a method for preparing multi-walled carbon nanotubes. The degree of graphitization of carbon nanotubes is not high (I_G / I_D=1.3)

In 2005, some scientists reported the preparation of Mg by urea combustion method 0.90 Fe x co y O(x+y=0.1) solid solution (Coquay P.; Peigney A.; De Grave E.; Flahaut E.; Vandenberghe R.E.; Laurent C., Fe / Co Alloys for the Catalytic Chemical Vapor Deposition Synthesis of Single-and Double- Walled Carbon Nanotubes (CNTs). 1. The CNT-Fe / Co-MgO System. The Journal of Physical Chemistry B [J] 2005, 109 (38): 17813-17824.), the specific surface area of ​​the resulting catalyst is small (less than 52m2 / g), and the preparation process of this method has a small amount of preparation, it is not easy to control the reaction rate, and it is extremely prone to explosion

In 2012, a study reported the preparation of (Al 2 -xFe x o 3 )-(y)ZrO 2 (x=0.017, 0.034 and 0.17 and y=0.15) ceramic nanocomposite catalysts (Beitollahi A.; Pilehvari S.; Sani M.F.; Moradi H.; Akbamejad M., In situ growth of carbon nanotubes in alumina-zirconiananocomposite matrix prepared by solution combustion method.CeramicsInternational[J].2012,38(4):3273-3280.), yet the catalyst metal lacks a strong interaction with the support, and the resulting carbon tube yield is lower than 23%, and I_G / I_D does not exceed 3

In 2018, a study reported the preparation of catalysts by sol-gel method (Kim P.; Lee C.J., The ReductionTemperature Effect of Fe-Co / MgO Catalyst on Characteristics of Multi-WalledCarbon Nanotubes.Catalysts[J].2018, 8(9 ).), the catalyst will expand violently and emit a large amount of heat in the reaction process, which will affect the reaction equipment and reaction safety, and is not suitable for large-scale reactions; not tall

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