Enhancing hydrogen production: Modelling the role of activated carbon catalyst in methane pyrolysis

Hydrogen obtained from natural gas pyrolysis is valuable in transitioning to cleaner energy sources, as it provides a cost-effective and environmentally sound alternative to other processes. Utilizing activated carbon particles as catalysts enhances methane conversion rates and helps reduce pyrolysis temperatures while avoiding the high costs and metal contamination risks associated with metal catalysts. This study presents a model for the decomposition of methane over carbon catalysts using a comprehensive kinetic approach. The model includes heterogeneous surface reactions for methane dissociation and carbon depositions. It also introduces a novel method that utilizes the relationship between pore structure and specific surface area to explain the long-term deactivation process of the particles. The results demonstrate good agreement with various deactivation experiments, showing how methane conversion rates decrease as the specific surface area of the particles decreases during the pyrolysis process. Importantly, the simulations confirm the catalytic role of these particles in the pyrolysis process and how their presence in the reactor fundamentally alters the dynamics of the process compared to an empty reactor. The proposed model takes into account the catalytic effects of activated carbon while addressing the challenges posed by its complex pore structures. The findings offer insights into optimizing catalytic methane pyrolysis, providing a pathway to more efficient hydrogen production while harnessing valuable solid carbon by-products.