Iron-Based Catalysts on Tailored Alumina Supports for COx-Free Methane Decomposition to H2 and Carbon.

Methane decomposition is a COx-free process for hydrogen generation that also produces valuable carbon nanostructures. The work herein focused on Fe-based catalysts supported on some common supports (Al2O3, ZrO2, SiO2) and on alumina modified by metal oxides (10SiAl, 10ZrAl, 10YAl, 10CeAl). The prepared catalysts were characterized in detail by XRD, BET, TEM, TPR, TGA, and Raman spectroscopy. Among the single-component supports, the 20Fe/Al2O3 (Fe-Al) catalyst exhibited the highest initial activity, with 69.4% CH4 conversion. Among all the catalysts studied, Fe-10ZrAl showed the best catalytic activity with a maximum CH4 conversion (76.5%) and H2 yield (74.1%). Furthermore, during regeneration cycles, the catalyst maintained CH4 conversion (90%) without detrimental carbon encapsulation. The performance of Fe-10ZrAl is attributed to the synergistic effect of the ZrO2 modifier which improves strong metal-support interactions, stabilizes active iron nanoparticles from thermal sintering, and allows a highly reversible in-situ carbide cycle. The Fe-10ZrAl catalyst is the most active, followed by the Fe-10YAl catalyst, owing to its improved reducibility. Our work demonstrates the key role of modified alumina structures for sustainable co-production of hydrogen and nanomaterials.