Tailoring Ni/KCC-1 catalyst with transition metals promoters for methane cracking: Insights into hydrogen and carbon nanomaterials Co-production

Catalytic methane decomposition (CMD) offers a promising approach for turquoise hydrogen production, facilitating the transition towards the 2050 net-zero carbon emissions while simultaneously generating valuable carbon nanomaterials. In this study, nanospherical hierarchical fibrous silica (KCC-1) was synthesized as the catalyst support using a microemulsion hydrothermal method, while 15 %Ni-5 %M/KCC-1 catalysts (where M = Ga, Cu, In, Mn, Mo) were prepared using a facile sonicated co-impregnation method to incorporate nickel as an active metal and second metal (M) as promoters. The structural, electronic, and catalytic properties of both unpromoted and promoted Ni-based catalysts were characterized by N₂ physisorption, XRD, SEM-EDS, TEM, XPS, H₂-TPR, TGA, and Raman spectroscopy. The incorporation of Cu and Ga into 15 %Ni/KCC-1 significantly improved catalytic activity and stability under harsh reaction conditions. Maximum methane conversions of 74 % were achieved at 650 °C and a GHSV = 6000 ml g⁻¹ h⁻¹ with Ni–Ga/KCC-1 and Ni–Cu/KCC-1 as Ga and Cu exhibit minimal interaction with produced carbon due to zero d-vacancies and therefore suppressed stable carbide formation. However, TEM, TGA, and Raman analyses revealed that Ni–Ga/KCC-1 facilitated the formation of high-quality multiwalled carbon nanotubes compared to Ni–Cu/KCC-1 catalyst. Overall, this research highlights the intricate balance between catalyst composition, structural integrity, and operational parameters in optimizing catalytic performance for methane decomposition.