Method for controlling bulk density of carbon nanotube agglomerate

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/m3 or more and less than 80 kg/m3,
• 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.