Method for controlling bulk density of carbon nanotube agglomerate

Patent metadata

Field	Value
Publication number	US-9809458-B2
Application number	US-201414438816-A
Country	US
Kind code	B2
Filing date	Sep 30, 2014
Priority date	Sep 30, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

The present invention relates to a method for producing a carbon nanotube aggregate whose bulk density is easily controllable. Therefore, the present invention provides a carbon nanotube aggregate suitable for use in various fields.

First claim

What is claimed is:

1. A method for producing a carbon nanotube aggregate, comprising:
calcining aluminum hydroxide at a primary calcination temperature of 300° C. to 500° C. to form a support comprising 40 wt % or more of AlO(OH),
impregnating a catalytic metal precursor on the support,
calcining the catalyst-containing support at a secondary calcination temperature of 550° C. to 800° C. to obtain a supported catalyst, and
bringing the supported catalyst into contact with a carbon-containing compound under heating to react with each other,
wherein the primary calcination temperature, the secondary calcination temperature, the amount of the catalyst supported or the reaction time is controlled such that the carbon nanotube aggregate has a bulk density of 10 kg/m 3 or more and less than 80 kg/m 3 ,
wherein the catalytic metal comprises cobalt (Co) and vanadium (V),
wherein at least a portion of the carbon nanotube aggregate is of a bundle type, and
wherein the method further comprises adding an organic acid such that the molar ratio of cobalt (Co) to organic acids is from 5.8:1 to 30:1 during the preparation of the supported catalyst, and the bulk density of the carbon nanotube aggregate is controlled by varying the amount of the organic acid added.

2. The method according to claim 1 , wherein the secondary calcination temperature is higher by 200 to 400° C. than the primary calcination temperature.

3. The method according to claim 1 , wherein the bulk density of the carbon nanotube aggregate increases with increasing secondary calcination temperature until 675° C. and thereafter decreases with increasing secondary calcination temperature.

4. The method according to claim 1 , wherein the catalytic metal is present in an amount of 5 to 30% by weight, based on the total weight of the catalyst.

5. The method according to claim 1 , wherein the content (x 1 ) of the catalytic metal and the bulk density (y) of the carbon nanotube aggregate satisfy the relation given by the following equation:
y=a 1 x 1 +b 1   (1)

where y represents the bulk density (kg/m 3 ), x 1 represents the content of the catalytic metal relative to the total weight of the catalyst and is from 10 to 30 wt %, a 1 is a constant determined by the reaction time and is from 4 to 7, and b 1 is a constant determined by the reaction time and is from −15 to −40.

6. The method according to claim 1 , wherein the bulk density of the carbon nanotube aggregate increases by 1.2 to 1.5 times in proportion to the time (hr) of the reaction with the carbon-containing compound.

7. The method according to claim 1 , wherein the number of moles (x 2 ) of the catalytic metal per mole of the organic acid and the bulk density (y) of the carbon nanotube aggregate satisfy the relation given by the following equation:
y=a 2 x 2 +b 2   (2)

where y represents the bulk density (kg/m 3 ), x 2 represents the number of moles of the catalytic metal per mole of the organic acid, a 2 is a constant from 1 to 1.5, and b 2 is a constant from 20 to 40.

8. The method according to claim 1 , wherein the reaction with the carbon-containing compound is carried out in a fluidized bed reactor.

Assignees

• Lg Chemical Ltd
• Lg Chemical Ltd

Inventors

• Kim Sungjin
• Son Seungyong
• Cho Dong Hyun
• Kang Kyungyeon
• Cha Jinmyung
• Woo Jihee

Classifications

• B01J23/70

  of the iron group metals or copper · CPC title

• B01J23/8472

  Vanadium · CPC title

• B01J35/0026

  Operations & Transport · mapped topic

• B01J21/185

  Carbon nanotubes (carbon nanotubes per se C01B32/15) · CPC title

• B01J23/22

  Vanadium · CPC title