The role of induction heating in catalytic methane decomposition over Fe/Al2O3

Catalytic methane decomposition (CMD) offers a direct pathway to CO2-free hydrogen by converting CH4 into H2 and solid carbon. However, its application is constrained by the need for efficient heat delivery to the catalyst and the rapid deactivation of metal catalysts due to carburization and carbon encapsulation. Coupling CMD with the high energy demand and greenhouse gas emissions of conventional external heating, alternative heating technologies that address catalytic limitations are desirable. In this work, CMD over Fe/Al2O3 was evaluated under conventional furnace heating (CFH) and induction heating (IH) conditions at temperatures ranging from 700 °C to 750 °C. IH produced higher initial CH4 conversion and slower deactivation, sustaining steady-state conversions that were up to 43% higher after 60 min on stream. Thermogravimetric analysis confirmed greater carbon deposition under IH compared to CFH, while derivative thermogravimetric profiles were broader and shifted to higher temperatures, consistent with the formation of more filamentous carbon. Raman spectroscopy indicated similar graphitic order, but X-ray photoelectron spectroscopy (XPS) revealed oversaturated Fe3C1+x in CFH and a higher graphitic-to-carbidic carbon ratio in IH. Scanning and transmission electron microscopy (STEM) supported these findings, showing that CFH terminated significant filament growth due to encapsulated Fe particles, whereas IH promoted sustained carbon filament growth. Multiphysics modeling predicted transient temperature oscillations at catalyst-susceptor interfaces, which may dynamically shift carbon solubility and mitigate continuous carburization of the Fe particles. The findings in this work highlight the importance of evaluating induction-heated catalytic systems with explicit consideration of dynamic process parameters and transient conditions, as well as their effects on the catalyst.