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

•Effect of the catalyst morphology was investigated.•FeMo/MgO catalyst (sol–gel) generates higher amount of carbon nanotubes.•A sponge-like structure of the catalyst increases the yield 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.

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