Method for producing Nano carbon tubes continuously and equipment

Abstract

This invention discloses high-efficiency method and apparatus for continuously producing carbon nanotubes. The apparatus is a multi-stage counter-current reaction apparatus. The method comprises: placing the catalyst in the pre-reactor or the main reactor, introducing mixed gases of H2 or CO, and N2 or Ar, reducing, then introducing raw material gas, reacting to obtain carbon nanotubes, and sending the expanded solid raw material to the next stage reactor for reaction. The gas flow and the solid raw material are arranged in counter-current contact mode in the reactors, which can increase the conversion rate of the solid raw material. This invention has such advantages as simple apparatus and easy operation, and is suitable for industrial production on the scale of tens of thousands of tons per year.

Description

technical field [0001] The invention belongs to the technical field of nano material preparation and chemical equipment. In particular, it relates to a high-efficiency continuous production method and device for carbon nanotubes using a multi-stage countercurrent reaction device. Background technique [0002] Under the concept of nano-agglomerated fluidization, the fluidized bed reactor was successfully used for large-scale preparation of carbon nanotubes (Wang Yao, et al. Agglomerated carbon nanotubes and its mass production in a fluidized-bed reactor. Physica B, 2002, 323:327-329). In view of the continuous increase in volume during the preparation of carbon nanotubes and the frequent movement of solid materials into and out of the reactor, a fluidized bed has great advantages over a fixed bed. [0003] The growth process of carbon nanotubes is a process of gradual volume expansion. As the reaction time prolongs, its reactivity gradually decreases, and the volume gradual...

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Problems solved by technology

[0005] For the preparation of single / double-walled carbon nanotubes, the reaction conditions and operating conditions required for the nucleation and growth of the catalyst are also significantly different. In order to reduce the high concentration of H generated during the reaction 2 The side effects caused by the catalyst. The initial nucleation and growth process of single / double-walled carbon nanotubes requires a high space velocity carbon source gas flow rate, and in the later stage of growth, in order to improve the carbon source conversion rate, it is necessary to reduce the space velocity of the carbon source gas. The difference between high and low space velocities As high as 2 to 100 times, at this time the single reactor also showed obvious disadvantages

[0006] In the early stage of carbon nanotube production, if the catalyst is not well fluidized, there may be agglomeration of the catalyst-carbon nanotube nano-agglomeration structure, which will block the reactor and stop production; in the later stage of growth, its density will generally gradually decrease to about 50g / L, at this time, the particles are extremely loose and porous, and the overlapping adhesion between particles is serious. This kind of adhesion between nanoparticles makes the fluidization performance drop rapidly, which may destroy the normal fluidization state, so how to avoid or solve this kind of unfavorable The condition of fluidization is the key to the continuous and stable operation of the fluidized bed reactor

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