METHOD FOR CONTROLLING BULK DENSITY OF CARBON NANOTUBE AGGLOMERATE

• US 20150298974A1
• Filed: 09/30/2014
• Published: 10/22/2015
• Est. Priority Date: 09/30/2013
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: KIM, SungJin, SON, Seungyong, CHO, Dong Hyun, KANG, KyungYeon, CHA, Jinmyung, WOO, Jihee
• Granted Patent: US 9,809,458 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B01J 21/185 Carbon nanotubes carbon nanotubes per se C01B32/15
• CPC Class Codes: B01J 23/22 Vanadium
• CPC Class Codes: B01J 23/28 Molybdenum
• CPC Class Codes: B01J 23/70 of the iron group metals or copper
• CPC Class Codes: B01J 23/745 Iron
• CPC Class Codes: B01J 23/8472 Vanadium
• CPC Class Codes: B01J 23/88 Molybdenum
• CPC Class Codes: B01J 23/8877 Vanadium, tantalum, niobium or polonium
• CPC Class Codes: B01J 35/31 Density
• CPC Class Codes: B01J 37/08 Heat treatment B01J37/0009, B01J37/0018 take precedence
• CPC Class Codes: C01B 2202/22 Electronic properties
• CPC Class Codes: C01B 32/158 Carbon nanotubes
• CPC Class Codes: C01B 32/162 characterised by catalysts

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.

Claims

1. A method for producing a carbon nanotube aggregate, comprising calcining aluminum hydroxide at a primary calcination temperature of 100°

C. to 500°

C. to form a support, supporting a catalytic metal precursor on the support, calcining the catalyst-containing support at a secondary calcination temperature of 100°

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/m³ or more.

2. The method according to claim 1, wherein the carbon nanotube aggregate has a bulk density of 100 kg/m³ or less.

3. The method according to claim 1, wherein at least a portion of the carbon nanotube aggregate is of a bundle type.

4. The method according to claim 1, wherein the secondary calcination temperature is higher by 200 to 400°

C. than the primary calcination temperature.

5. The method according to claim 1, wherein the primary calcination temperature is from 300 to 500°

C. and the secondary calcination temperature is from 550 to 800°

C.

6. The method according to claim 1, wherein the catalytic metal comprises Fe, Co, Mo, V or a combination of two or more thereof.

7. 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.

8. 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.

9. The method according to claim 1, wherein the content (x₁) of the catalytic metal and the bulk density (y) of the carbon nanotube aggregate satisfy the relation given by the following equation:

y=a₁x₁+b₁ 

 

(1)

where y represents the bulk density (kg/m³), x₁ represents the content of the catalytic metal relative to the total weight of the catalyst and is from 10 to 30 wt %, a₁ is a constant determined by the reaction time and is from 4 to 6.5, and b₁ is a constant determined by the reaction time and is from −

15 to −

40.

10. 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.

11. The method according to claim 1, wherein an organic acid is added in a molar ratio of 5:

1 to 30;

1 relative to the catalytic metal for 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.

12. The method according to claim 11, wherein the number of moles (x₂) 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=a₂x₂+b₂ 

 

(2)

where y represents the bulk density (kg/m³), x₂ represents the number of moles of the catalytic metal per mole of the organic acid, a₂ is a constant from 1 to 1.5, and b₂ is a constant from 20 to 40.

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

14. A carbon nanotube aggregate produced by the method according to claim 1.

15. A composite material comprising a carbon nanotube aggregate produced by the method according to claim 1.

16. The composite material according to claim 15, wherein the composite material has a conductivity within the range given by the following inequality:

0.1x₃+1≦

Log R≦

0.1x₃+4 

 

(3)

where x₃ represents the bulk density (kg/m³) of the carbon nanotube aggregate and R represents the surface resistivity (ohm/sq) of the composite material