US Patent 7585482 Method and apparatus for producing carbon nanotubes

A method of purifying a single-walled carbon nanotube catalytic product having the steps of providing a catalytic product including single-walled carbon nanotubes, and a Group VIII and/or Group VIb transition metal, exposing the catalytic product to a heated oxidative gas to provide a treated carbon nanotube product including single-walled carbon nanotubes and the Group VIII and/or Group VIb transition metal, and exposing the treated carbon nanotube product to an acid to separate the single-walled carbon nanotubes from the Group VIII and/or Group VIb transition metal. The catalytic product may include a support material and amorphous carbon.