oa South African Journal of Chemistry - The effect of synthesis parameters on the catalytic synthesis of multiwalled carbon nanotubes using Fe-Co / CaCO3 catalysts : research article
|Article Title||The effect of synthesis parameters on the catalytic synthesis of multiwalled carbon nanotubes using Fe-Co / CaCO3 catalysts : research article|
|© Publisher:||South African Chemical Institute (SACI)|
|Journal||South African Journal of Chemistry|
|Author||Sabelo D. Mhlanga, Kartick C. Mondal, Robin Carter, Michael J. Witcomb and Neil J. Coville|
|Publication Date||Jan 2009|
|Pages||67 - 76|
|Keyword(s)||Bimetallic catalyst, Carbon nanotubes, Cobalt, Iron and Synthesis|
Fe-Co bimetallic catalysts supported on CaCO3 were prepared by a wet impregnation, a deposition-precipitation and a reverse micelle method. The sizes of the Fe and Co particles were not affected by the Fe and Co sources (nitrate, acetate) when the wet impregnation and deposition-precipitation methods were used. 'Clean' multi-walled carbon nanotubes (MWCNTs) were obtained from all three Fe-Co synthesis procedures under optimal reaction conditions. The CNTs produced gave yields ranging from 623 % to 1215 % in 1 h under the optimal conditions, with similar outer diameters (o.d.) of 20-30nm and inner diameters (i.d.) ~10 nm. The Fe / Co catalyst formed in the wet impregnation method revealed that the yield, diameter and purity of the CNTs were influenced by the C2H2 / N2 ratio, time and temperature. All the methods gave high-quality CNTs after short reaction times but the quality deteriorated as the synthesis time was increased from 5 to 360 min. Indeed, the most influential parameter in controlling CNT purity, length and o.d. was found to be the synthesis time. The as-synthesized CNTs were purified using a single-step mild acid treatment process (30 % HNO3), which readily removed the support and metal particles.
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