A Perspective on Supported Catalysts for Methane Pyrolysis: Toward Hydrogen Production and Synthesis of Crystalline Carbon Materials

H 2 production is increasingly vital in decarbonizing heavy-emission sectors. Currently, steam methane reforming (SMR) is used industrially for H 2 production but generates significant CO 2 emissions that highlight the urgent need for more low-carbon processes for H 2 generation. Methane pyrolysis presents a promising alternative by sequestering carbon in its solid form but faces challenges in catalyst durability and cost-effectiveness at the industrial scale relative to SMR. This perspective first discusses the fundamental properties essential for an ideal pyrolysis catalyst, focusing on intrinsic factors such as catalytic activity, carbon nucleation, and carbon growth mechanisms. Building on these fundamental concepts, it then discusses practical challenges relevant to the scaling of supported catalysts, including how to effectively assess catalyst cost-effectiveness and the limitations associated with achieving these metrics. Strategies to increase the lifetime of supported catalysts and the limitations of an ideal supported catalyst due to reactor design constraints are discussed, highlighting the opportunities and barriers to overcome in commercializing methane pyrolysis for hydrogen production. While supported catalysts offer the ability to enhance the lifetime during pyrolysis and flexibility in active phase and carbon transport tunability, existing challenges associated with balancing CNT synthesis and metal dusting, cost of scalability, and mass and heat transport for industrial pyrolysis need to be overcome.