US Patent 7604790 - CNT purification using sulfidation

http://www.freepatentsonline.com/7604790.html

This patent from Samsung teaches a way to remove carbon impurities formed during carbon nanotube production based on a sulfidation reaction. An article (link) from 2005 from the inventors explains how the process improves the characteristics of nanotube field effect transistors. Claim 1 reads:

1. A method of removing carbonaceous impurities in a carbon nanotube, the method comprising:

preparing sulfur and carbon nanotubes in a sealed space, the sulfur being in a solid state; and

sulfiding a surface of the carbon nanotubes to remove carbonaceous impurities formed on the carbon nanotubes,

wherein the sulfiding includes heating the sulfur and the carbonaceous impurities above a temperature to induce a sulfidation reaction between the sulfur and the carbonaceous impurities and removing carbon disulfide (CS2) resulting from the sulfidation reaction of sulphuric evaporated gas and the carbonaceous impurities formed on the surface of the carbon nanotubes.