Session 2A: Hydrogen from Natural Gas (Methane)

Methane pyrolysis for hydrogen production is critical for decarbonization efforts, provided that the co-produced solid carbon can be separated affordably and valorized at scale. Studies demonstrate the potential of molten metal alloy catalysts operating in bubble column reactors, achieving industrial-relevant productivities (10⁻⁵ to 10⁻⁶ mol/s/cm³). Key catalytic mechanisms involve surface segregation and surface charge distribution, with electronic effects significantly influencing C–H and C–O bond activation rates. For instance, copper-indium alloys are shown to catalyze the formation of multi-walled carbon nanotubes (CNTs) from nanodroplets, with subsequent heat treatment enabling effective catalyst removal. Another approach, utilizing floating-catalyst gas-phase reactors with iron and sulfur precursors and gas recycling, has demonstrated net hydrogen production (84.5 vol% H₂) alongside CNTs. Significant advances in post-processing have led to CNT fibers with tensile strengths exceeding 8 GPa and recent reports of electrical conductivity surpassing copper and aluminum, making them competitive with high-end carbon fibers. Reactor productivity has increased 100-fold, though further optimization of catalyst selectivity and residence time is needed to prevent undesirable radial growth and ensure high-quality product. For industrial-scale application, a non-catalytic methane pyrolysis process aims for cost parity with steam methane reforming (SMR) coupled with carbon capture, utilization, and storage (CCUS). While initial Gen 1 reactors demonstrated hydrogen and carbon yields, achieving consistent commercial-grade carbon black requires improved reactor temperature and retention time control. New Gen 2 reactor architectures are being developed to increase hydrogen capacity and ensure consistent carbon quality. Overall, the economic viability and scalability of methane pyrolysis are contingent on developing robust carbon valorization pathways, with new markets beyond traditional carbon black, such as in construction materials, advanced conductors, and aerospace composites, being essential for accommodating the substantial volumes of carbon produced. Considerations for the long-term fate of carbon and the reduction of upstream fugitive methane emissions are also critical for the overall environmental impact. Welcome from the Chair Molten metal catalyzed carbon nanotube production Pyrolysis of Methane to Bulk CNT Materials: Manufacturing Carbons that Are Useful for Manufacturing EKONA: Our Journey to Develop Low-Cost, Clean Hydrogen from Methane Pyrolysis Discussion

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