Use of FeCrAlloy as a feasible substrate in the structuration of a Fe-Mg-Al catalyst for catalytic decomposition of methane

Catalytic decomposition of methane (CDM) is a promising process for producing CO x -free hydrogen and valuable carbon nanomaterials, although its industrial implementation is limited by catalyst deactivation and drawbacks associated with powder catalyst. In this work, a Fe-Mg-Al catalyst was structured onto FeCrAlloy monoliths to evaluate the feasibility of structured catalytic systems under CDM conditions. The structured catalysts were prepared via washcoating and systematically compared with their powder counterparts under different pre-treatments (N 2 and H 2 /N 2 ). Structuration improved catalytic performance, carbon productivity and stability, enabling sustained activity without deactivation during the reaction. The pre-treatment atmosphere affected both catalyst behaviour and substrate stability. N 2 pre-treatment promoted higher activity, whereas H 2 /N 2 preserved the FeCrAlloy substrate by maintaining a chromium-rich layer. Characterization by XRD, Raman, and TEM revealed the formation of multi-walled carbon nanotubes (MWCNTs), with morphology influenced by catalyst structuration and pre-treatment. These findings support structured Fe-based monolith catalysts as scalable systems for CDM.