Synthesis of high quality single-walled carbon nanotubes on natural sepiolite and their use for phenol absorption

Natural sepiolite mineral was used as a catalyst and catalyst support for the efficient growth of single-walled carbon nanotubes (SWCNTs). With the introduction of hydrogen, uniform active metal nanoparticles can be formed in the fibrous structure of sepiolite ore. High-quality SWCNTs with few defects and a large aspect ratio (over 10⁴) were synthesized. The structure of the CNTs was modified by controlling the catalyst composition with ion-exchange method and changing the growth conditions. The 1 wt.% Fe-based catalyst exhibited excellent activity for the growth of SWCNTs, while the Co/Mo-based catalyst preferred to grow small diameter SWCNTs. The reaction temperature showed a sensitive selectivity to the chirality and diameter distribution of the SWCNTs produced. Catalysts based on the sepiolite can also afford the effective growth of SWCNTs in a fluidized bed reactor. As-grown SWCNTs/calcined-sepiolite demonstrated excellent ability of phenol adsorption, with an adsorption capacity of 155.8 mg/g, which was much higher than that on natural sepiolite (12.7 mg/g).