Wednesday, January 12, 2011

US Patent 7868333 - Demetallization of CNTs

The fabrication processes for carbon nanotubes usually results in metallic residue that needs to be removed prior to use of the nanotubes. This patent from E.I. du Pont teaches a purification technique which removes the metallic residue without damaging or oxidizing the nanotubes. Claim 1 reads:

1. A process comprising:

a) forming a first suspension of carbon nanotubes containing metal residues in a first solvent;

b) contacting the first suspension with an active metal agent to form a second suspension of carbon nanotubes containing metal residues;

c) contacting the second suspension with carbon monoxide gas to form carbon monoxide-treated carbon nanotubes; and

d) isolating the carbon monoxide-treated carbon nanotubes;

wherein steps (a), (b) and (c) are performed in an airless atmosphere.