Method for producing carbon nanotubes

Patent metadata

Field	Value
Publication number	US-9862611-B1
Application number	US-201715666742-A
Country	US
Kind code	B1
Filing date	Aug 2, 2017
Priority date	Aug 4, 2016
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

Disclosed is a method for producing a carbon nanotube, including supplying a carbon nanotube and a catalyst to a reactor in a predetermined order or simultaneously and fluidizing them to form a fluidized bed, wherein a difference in minimum fluidization velocities (ΔV) according to Formula 1 below is 5 cm/s or less: [Formula 1] Difference in minimum fluidization velocities (ΔV, cm/s)=|V cat −V cntproduct | wherein V cat is a minimum fluidization velocity of catalyst, and V CNTproduct is a minimum fluidization velocity of carbon nanotubes supplied to a reactor in the step of forming a fluidized bed.

First claim

What is claimed is:

1. A method for producing carbon nanotubes, comprising: supplying carbon nanotubes and catalysts to a reactor in a predetermined order or simultaneously and fluidizing them to form a fluidized bed,
wherein a difference in minimum fluidization velocities (ΔV) according to the following formula 1 is not more than 5 cm/s:
Difference in minimum fluidization velocities (Δ V , cm/s)=| V cat −V CNT product |  [Formula 1]

wherein V cat is a minimum fluidization velocity of catalyst, and V CNT product is a minimum fluidization velocity of carbon nanotubes supplied to a reactor in the step of forming a fluidized bed.

2. The method of claim 1 , wherein the minimum fluidization velocity of the catalyst is 0.1 cm/s to 10 cm/s.

3. The method of claim 1 , wherein the catalyst has a particle density of 1,300 kg/cm 3 to 2,200 kg/cm 3 .

4. The method of claim 1 , wherein the catalyst has a diameter of 10 μm to 300 μm.

5. The method of claim 1 , wherein, in the step of forming the fluidized bed, when the carbon nanotubes and the catalyst are filled in the reactor to form a packed bed, the packed bed is formed to have a ratio of height to diameter (L/D) of 1 or more.

6. The method of claim 1 , wherein, in the step of forming the fluidized bed, the carbon nanotubes and the catalyst are supplied to the reactor so that a weight ratio of the carbon nanotubes to the catalyst contained in the fluidized bed is 1:0.5 to 1:1.

7. The method of claim 1 , further comprising growing carbon nanotubes on the catalyst by reacting a source gas and the catalyst.

8. The method of claim 7 , wherein, in the step of growing the carbon nanotubes, the temperature difference (ΔT) according to the following formula 2 is 20° C. or less:
Temperature difference (Δ T , ° C.)= T 1 −T 2   [Formula 2]

wherein T 1 and T 2 indicate a temperature of the fluidized bed as measured at two different heights, each being selected arbitrarily from a height ranging from the bottom to the top of the fluidized bed.

Assignees

• Sk Innovation Co Ltd
• Sk Global Chemical Co Ltd

Inventors

• Kim Ji-Min
• Sung Min-Ji
• Kwon Yong-Tak
• Kim Sang-Uk
• Kim Ok-Youn
• Son Sung-Real
• Son Jung-Yul

Classifications

• C01B32/162 Primary

  characterised by catalysts · CPC title

• Y10S977/843

  Gas phase catalytic growth, i.e. chemical vapor deposition · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• B01J8/0015

  Feeding of the particles in the reactor; Evacuation of the particles out of the reactor · CPC title

• Y10S977/742

  Carbon nanotubes, CNTs · CPC title