Abstract: The Ni(OH)2/SiO2 binary colloid was prepared using Ni(NO3)2·6H20 and(C2H50)4Si04 as starting materials and was used to form NiO/Si02 composite pow-der by hydrothermal method and desiccant method in open air respectively. Multi-walled carbon nanotubes (MWCNTs) were synthesized respectively by chemical vapor deposition using the NiO/Si02 catalyst prepared by different methods. The phase and morphology of the catalysts and the morphology, output yield and purity of MWCNTs were compared by XRD, TEM and SEM. The results show that the catalyst powder pre-pared by hydrothermal method, compared with that by desiccant method, is smaller, better dispersion and has stronger catalytic activity. Pure MWCNTs with smaller tube diameter and narrow range could be obtained at a high yield using that NiO/Si02 pow-der oreoared by hvdrothermal method as catalyst.

Key words: hydrothermal method, dry method at atmosphere, carbon nanotube,