ABSTRACT

Yousheng Tao,a,b Morinobu Endo,b,c and Katsumi Kanekoc a State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China b Institute of Carbon Science and Technology, Shinshu University, 1-17-1 Wakasato, Nagano 380-8553, Japan c Research Center for Exotic Nanocarbons, Shinshu University, 1-17-1 Wakasato, Nagano 380-8553, Japan taoys@tom.com and taoyoushengjp@yahoo.co.jp

and/or porous particles. By the “expanding universe mechanism” [7], CNTs continuously grow and the catalyst particles rupture and disintegrate, resulting in more than 95 wt% CNT agglomerates in the products [8]. The impurities of CNTs are the by-products such as metal-encapsulated nanoparticales, metal nanoparticles, and some amorphous carbon. Compared to arc discharge and laser ablation methods, the CCVD method produces CNTs with high space-time yield, low amorphous carbon, and medium carbon purity [8-10]. Figure 17.2 shows the Bayer process for industrial production of MWCNTs [8]. A repetition of postsynthesis treatment containing acid reflux and annealing is generally needed for the purification of the as-grown CNTs. There are many companies in the world that have produced commercial CNTs over 100 tons annually [8, 11]. Work is now in progress to make the control of CNT morphology, diameter, the number of layers and chirality [9, 12-16].