Synthesis of lanthanum oxide supported transition metal-based catalysts for clean hydrogen production: The role of reducibility

Transition metal-based catalysts containing 20 wt% of nickel, cobalt, iron, and molybdenum doped over lanthanum dioxide (La₂O₃) were investigated for clean hydrogen production. The diffraction patterns showed the formation of corresponding metal oxides and their spinel species. The reduction profiles indicated the unique initial reduction temperatures that played a role in the catalytic performance. The activity profiles indicated that nickel-based catalyst (Ni-La) outperformed the rest of the catalysts with an initial activity of 82.3 % that reaches 83.6 % at the end of 170 min time-on-stream. The rest of the catalysts suffered deactivation over time and hence Ni-La turned out to be the active and stable catalyst among the tested catalysts. The high-resolution transition electron microscopy images of the best performing catalyst (Ni-La) revealed the growth of multiwalled carbon nanotubes and carbon formation followed simultaneously tip- as well as base-growth mechanisms.