Purification of carbon nanotubes by vacuum high temperature treatment (Chinese patent) Application Number(s): 03120818.5 Inventor Name(s): WANG Y, WEI F, LUO Guohua, HUANG Wei Patent Assignee Name(s) and Code(s): UNIV QINGHUA (UYQI) Abstract: NOVELTY - The present invention relates to vacuum high temperature purification of carbon nanotubes. DETAILED DESCRIPTION – This invention provides a feasible method of obtaining super-highly purified carbon nanotubes. Transition metal catalysts (Fe, Co, Ni, Mo) and metal catalyst carriers (Al2O3, MgO, SiO2), which remain in the raw product of carbon nanotubes produced by catalytic chemical vapor deposition method, can be efficiently eliminated by a vacuum high temperature operation. After heated at 2000℃ for 5 hours, the purity of carbon nanotubes can be increased from 86% to 99.93％，and the content of the transition metal is reduced to 0.05%. Under the permitted temperatures, the simple and efficient purification process will not cause any damage to carbon nanotubes.