(582cd) Catalytic Decomposition of Methane into COx Free Hydrogen and Carbon Nanotubes over Mono and Bimetallic Ni, Fe, Co Catalysts

Methane is the major
component and the most stable hydrocarbon of natural gas. We have investigated
the catalytic cracking of methane as an alternative route for the production of
carbon nanofibers (CNFs) and COx-free H₂ (Scheme 1). Mono and
bimetallic Ni, Fe, Co catalysts were prepared on SiO₂ support by
incipient impregnation technique. The effect of doping of metals (Ni-Fe, Ni-Co
and Fe-Co) with different mole ratios on the activity and stability of the
reaction is investigated here. The performance of the catalyst is evaluated at
a constant temperature (T = 650 °C) with a flow rate 70ml/min. (30% CH₄/N₂).
After the catalyst screening, catalyst regeneration study was performed on the
most stable catalyst. The physico-chemical characteristics are evaluated by XRD
analysis, TPR, H₂-chemisorption, HR-TEM and BET surface areas of
fresh and used forms of catalysts. XRD and TPR analysis of the fresh catalysts
confirmed the alloy formation in the bimetallic catalysts. TEM characterization
of the spent catalyst indicated that carbon deposits on the catalyst in the
form of hollow cylindrical filaments or carbon nanotubes, with the metal
particle located on the tip of each filament. It was also observed that bimetallic
catalysts produce a carbon nanotube with a smaller diameter compared to the
monometallic ones. A detailed study on the structural characteristics and the
mechanism of carbon nanotube formation is in progress.

Scheme 1: Catalytic decomposition of CH4 into COx free hydrogen and
carbon nanotubes