Microstructural study of FeMo/MgO catalysts prepared by sol-gel and co-impregnation and their relationship with the growth of carbon nanotubes

Multiwall carbon nanotubes (MWCNTs) were synthesized using p-xylene and FeMo/MgO catalysts prepared by two methods (co-impregnation and sol-gel). Carbon nanotubes with uniform diameters were obtained by catalytic chemical vapor deposition at 900°C using FeMo/MgO catalyst prepared by sol-gel method. The sol-gel method resulted in a higher yield than the co-impregnation method; this was attributed to the better dispersion of the metallic nanoparticles due to the sponge-like structure. Additionally, MWCNTs with lower metals content were obtained after three steps of purification.