The examination of NiO and CoOx catalysts supported on Al2O3 and SiO2 for carbon nanotubes production by catalytic chemical vapor deposition of methane.

The effects of catalyst components on the synthesis of carbon nanotubes (CNTs) are always the concern of many. The aimof this work is to examine the dependence of the morphology of CNTs formed on the nature of NiO and CoOx catalystssupported on Al2O3 and SiO2 at two different synthesis temperatures, i.e. 550oC and 700oC, respectively. Catalytic chemicalvapor deposition (CCVD) of methane was adopted for synthesizing the nanotubes materials. The developed catalysts werecharacterized by X-ray diffraction (XRD) and temperature programmed reduction (TPR). The morphology of the producedcarbon nanostructures was analyzed by transmission electron microscopy (TEM). The experimental result shows that CNTswere presence on the surfaces of most of the tested catalysts. The yield of the CNTs produced over these catalysts wascalculated. It was found that the yield decreased in the order of NiO/SiO2>CoOx/SiO2>CoOx/Al2O3>NiO/Al2O3 for thereaction at 550oC and in the order of NiO/SiO2>CoOx/Al2O3>CoOx/SiO2>NiO/Al2O3 at 700oC. The morphological analysisreveals that the structure of the CNTs depends upon the effects of metal-support interaction (MSI) and the synthesistemperature.