Effect of $Al_2O_3/Fe$ Ratio on Characteristics of Carbon Nanotubes Prepared by Catalytic Chemical Vapor Deposition

The effect of compositions of $Al_2O_3$ in the mixed $Fe/Al_2O_3$ catalysts on the synthetic behaviors of carbon nanotubes (CNTs) by catalytic chemical vapor deposition (CCVD) process was investigated in wide range of the mixture ratios of support materials. CNTs were synthesized with $Fe/Al_2O_3$ catalysis under the condition of 40 min in synthetic time, and 923 K of synthetic temperature using $C_2H_4$ and $H_2$ as synthetic and carrier gas, respectively. The carbon yield with the content of $Al_2O_3$ showed in a parabolic curve and the maximum carbon yield was 40 wt.% of $Al_2O_3$. As the mixture ratio of $Al_2O_3$ increased, decreasing tendency was observed in the diameter of CNTs. Specific surface areas of CNTs were increased with the increase of the mixture ratio of $Al_2O_3$.