Many researchers have suggested various catalysts and synthesis methods to enhance hydrogen (H₂) production efficiency and replace the noble catalyst in the methane (CH₄) pyrolysis process. In particular, nanocomposites incorporating nickel (Ni) have shown outstanding pyrolysis performance due to their high activity. In the present study, a triple thermal plasma system is employed to synthesize Ni nanocomposites, Ni-cobalt (Ni-Co) and Ni-plated carbon nanotube (Ni-CNT). We then examine the catalytic performance of the synthesized Ni nanocomposite using a CH₄ pyrolysis system. A field-emission scanning electron microscopy analysis with energy-dispersive X-ray spectroscopy mapping demonstrates that Ni-Co and Ni-CNT are successfully synthesized through the thermal plasma system. From the results of CH₄ pyrolysis using the synthesized Ni composite, the Ni-Co and Ni-CNT show lower CH₄ conversions of 29.3 and 45.7 %, respectively, than that of pure Ni at 45.8 % because of a thin oxygen layer formed on the particle surface. The Ni nanocomposite meanwhile exhibits more efficient performance than pure Ni in terms of H₂ selectivity. In particular, Ni-Co has higher H₂ selectivity of about 45 % due to its lower surface area compared to Ni-CNT. This work demonstrates the possibility of synthesizing Ni nanocomposites using triple thermal plasma for CH₄ pyrolysis.

Keywords: Thermal plasma, Methane pyrolysis, Nanocomposite, Nickel, Catalysts