Synthesis of hydrogen and carbon nanotubes over copper promoted Ni/SiO2 catalyst by thermocatalytic decomposition of methane

• Hydrogen and carbon nanotubes were synthesized from methane decomposition over Ni–Cu/SiO2 catalyst.
• Different catalysts were used to optimize experimental conditions and hydrogen production.
• Maximum methane conversion (88%) was obtained over 50%Ni–10%Cu/SiO2 catalyst at 750 °C.
• Characterization of catalysts by BET surface area, XRD, TPR, Chemisorption, TGA, SEM and HRTEM analysis.

This work presents thermocatalytic decomposition of methane for the production of hydrogen and carbon nanotubes over Ni and Cu promoted Ni catalysts synthesized by wet impregnation method using SiO2 support. Effect of important parameters such as reaction temperature, metal loading, Ni/Cu ratio and gas hourly space velocity (GHSV) on methane decomposition and hydrogen yields were examined. Incorporation of copper on nickel leads to an increase in the methane conversion/hydrogen yield. Among the various catalysts tested, 50%Ni–10%Cu/SiO2 catalyst resulted in highest activity in terms of methane conversion and carbon yield, however catalytic activities decreased rapidly at high promoter (Cu/Ni) ratio. Effect of regenerated catalysts showed no significant decrease in methane conversion up to second cycles of regeneration. Decrease in the space velocity of methane was favorable to promote the methane conversion. The structural and morphological nature of the calcined and spent catalyst was performed by BET surface area, temperature-programmed reduction (TPR), Chemisorption, X-ray diffraction (XRD), thermo gravimetric (TG), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis.