Comprehensive Review on Methane Pyrolysis for Sustainable Hydrogen Production

The reliance on natural gas as a fossil fuel often overshadows its potential for clean energy transformation. In contrast with the steam methane reforming (SMR) process, renowned for its substantial CO₂ emissions, methane pyrolysis (MP) stands out for its capability to produce hydrogen without any accompanying CO₂ byproducts. Additionally, MP presents the added advantage of generating valuable solid carbon co-products. The primary focus of this review is the commercialization or large-scale application of the MP process. This necessitates a detailed investigation into process design refinement, the selection between catalytic or non-catalytic processes, and the emergence of mature reactor types suitable for commercial scalability. This review further explores the various kinds of solid carbon (carbon black, carbon nanotubes, carbon nanofibers, and graphite) produced during MP, analyzing the process conditions for targeted synthesis and their potential market applications. Techno-economic considerations of different MP processes are evaluated, along with potential integration strategies with renewable energy sources (solar-driven reactors) and existing technologies (SMR and gasification) to accelerate progress toward net-zero emissions. This review underscores the exciting potential of MP for a cleaner hydrogen future while creating economic value from carbon co-products.