Highly Stable Ni–Red Mud Catalysts for CO₂-Free Hydrogen and Valuable Carbon from Natural Gas

The utilization of red mud as a catalyst support has been investigated to produce high-value carbon and CO_x-free hydrogen from natural gas. Nickel impregnation between 10 wt% to 20 wt% over red mud generates more active species in the form of nickel oxide; however, nickel–red mud interaction also generates less active spinel species (NiFe₂O₄). The red mud itself deactivates quickly during the production of hydrogen from the decomposition of methane; however, nickel-based red mud-supported catalysts have shown significant improvement in the activity results. For instance, the catalyst with 20 wt% nickel supported by red mud demonstrates a stable methane conversion as high as 75%. The reduction kinetics analysis demonstrated the lowest reduction in activation energy of 83 kJ/mol for 20Ni-PRM which played a major role in the excellent activity and stability of this catalyst. The post-reaction catalyst characterization results indicate the formation of multi-walled carbon nanotubes, as evidenced by high resolution transition electron microscope and thermogravimetric analyses.